Conception et réalisation d'un filtre de Fabry-Perot intégré sur un micro-banc optique en silicium

Ce travail s'inscrit dans le domaine des micro systèmes optiques. Le travail a consisté à concevoir et réaliser un prototype de filtre spectral de type Fabry-Perot. Ce type de composant a de nombreuses applications, tant dans le domaine des télécommunications optiques que dans le domaine des capteurs interférométriques. L'objectif est ici de réaliser un micro filtre dont la longueur optique peut être plus importante que dans les travaux publiés précédemment. Ce filtre peut, de plus, être adapté à différents types de longueurs d'onde. Il s'agit d'un composant se présentant sous la forme d'un micro-banc optique, ce qui rend aisée son intégration sur des montages plus complexes. Dans une première partie, une architecture a été proposée incluant un micro actionneur thermique permettant de déplacer une plate forme supportant une micro lentille. Cette lentille permet de collimater le faisceau sortant d'une diode laser fibrée. Les faces planes des lentilles jouent le rôle de miroirs défmissant la cavité de Fabry- Perot. Un modèle analytique et un modèle par éléments finis ont été développés pour étudier le comportement de l'actionneur thermique. Une bonne corrélation a été trouvée entre les deux modèles permettant d'étendre l'étude par éléments finis à tout type de géométrie. Différents procédés technologiques ont ensuite été développés permettant de résoudre les différents problèmes de micro fabrication rencontrés (compensations des sous-gravures, obtention de flancs verticaux...). Des caractérisations électromécaniques ont permis de vérifier que les températures et les déplacements expérimentaux sont bien en accord avec les résultats obtenus par les simulations. Les comparaisons entre les modèles et l'expérience ont permis de valider la bonne compréhension des phénomènes observés. Enfin, un banc de caractérisation optique a permis de mesurer la finesse du filtre. Une finesse de 25 a été obtenue à la longueur d'onde de 830 nm.This work is an example of Micro Optical Electrical Mechanical Systems (MOEMS). The aim was to realize a tunable Fabry-Perot filter with an optical length less important than in the previous works. This kind of device bas many applications for the telecommunications systems and the interferometric sensors. This filter which is integrated to an optical bench can work in different wavelengths. It's an example of a full-wafer structuring process which makes use of the advantage of silicon machining. Anisotropic etching techniques allow the fabrication of low cost structures with a very high precision. ln the first part, we propose a system with a micro thermal actuator which allow the displacement of a micro-lens supported by a movable silicion frame. This lens permits the focusing of the beam which results from an optical fiber or a Laser diode. The Fabry-Perot cavity is obtained by the deposition of reflective layers to form the mirrors on the exit facet of the first lens and the input facet of the second one. We have mainly worked on the actuator modeling and we present two models of a thermomechanical in-plane microactuator by using an analytical model and a Finite Element simulation. We demonstrate a good agreement between both models. This study shows that we can develop this model for more complex structures. Different technological processes have been developped to solve some etching problems (the use of compensations to avoid under-etching, perfect vertical walls...). Comparisons between theory and experimental results (temperature and displacement) validate the steady-state conditions and demonstrate the importance of several thermal phenomena. The actuator bas been successfully used in a Fabry-Perot interferometer : a finesse of 25 was obtained for a 830 nm laser diode.BESANCON-BU Sciences Staps (250562103) / SudocSudocFranceF

Étude par microspectrométrie Raman de matériaux et de composants microélectroniques à base de semi-conducteurs III-V grand gap

Les semi-conducteurs à base de composés III-V de type GaN présentent de nombreux avantages liés essentiellement à leur grande bande interdite - par rapport aux semi-conducteurs traditionnels Si, ou III-V des filières GaAs. De plus, il est possible de former, comme pour les semi-conducteurs traditionnels III-V des hétérojonctions de type HEMT (High Electron Mobility Transistor) AlGaN/GaN permettant d obtenir à la fois une forte densité de porteurs confinés à l hétérojonction et des mobilités électroniques élevées. Ces composants sont à l heure actuelle les candidats les plus prometteurs pour des applications hyperfréquences de puissance. Cependant, l échauffement observé au cours du fonctionnement et les différentes étapes de réalisation des composants ont un impact anormal sur les performances intrinsèques du composant. La microspectrométrie Raman est une technique non-destructive et sans contact avec une résolution spatiale submicronique, adaptée à l étude des HEMTs AlGaN/GaN en fonctionnement. L utilisation de différentes longueurs d onde excitatrices visible et UV permet de sonder les hétérostructures à différentes profondeurs de pénétration. Les informations obtenues avec cette technique d analyse sont la composition de l hétérostructure, les contraintes entre les différentes couches, la résistance thermique aux interfaces, la qualité cristalline des différentes couches, le dopage et le comportement thermique des différentes couches. Le développement d un système de microspectrométrie Raman UV résolue en temps a permis d analyser le comportement thermique transitoire des HEMTs AlGaN/GaN en fonctionnement et plus particulièrement dans la zone active du composant.GaN based semi-conductors present numerous advantages linked essentially to their large band gap as compared to traditional Si systems. In addition, it is possible to form hetero-junction III-V HEMTs (High electron Mobility Transistor) like AlGaN/GaN which makes it possible to obtain both a large density of carriers confined at the heterojunction and a high electronic mobility. At the moment these systems are the most promising for high-power hyperfrequency applications. However heating occurs during operation which results in abnormal impacts on the performance of the microelectronic components. Micro-Raman characterization of these components makes it possible to understand the influence of the behaviour of the semi-conductor materials on the performance of the HEMTs in hyperfrequency mode. Micro-Raman spectroscopy being non-destructive and possessing a submicronic spatial resolution is well adapted to such studies. The use of various UV and visible excitation wavelengths (266 and 632.8 nm) makes it possible to probe the heterostructures at different penetration depths. We present results of micro Raman studies for analysis of the heterostructure composition, the stresses between layers, the thermal boundary resistance, the crystalline quality of each layer and the doping and thermal behaviour of each layer. In addition, recent time-resolved UV micro-Raman studies have made it possible to analyse the transient thermal behaviour of AlGaN/GaN HEMTs under voltage and in the active area of the component.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Patrimoines et images animées : mutualiser les regards

Dans les transports en commun, dans les grandes surfaces ou dans les foyers, les écrans se sont multipliés, supports d’images animées dès lors omniprésentes. Les lieux de patrimoine, et en particulier les musées, n’ont pas échappé à cette évolution sociétale. En diverses discipline (muséologie, études cinématographiques ou histoire), les recherches envisagent encore timidement cette question et trop souvent sans véritablement dialoguer entre elles. Faisant suite à un colloque, organisé en 2010, où s’étaient rencontrés chercheurs et professionnels, ce numéro propose en neuf de textes de poser quelques jalons pour une approche croisée des usages et pratiques des images animées en matière de patrimonialisation. Il se pose aussi la question des sources pour des études futures et propose à cet égard plusieurs ensembles documentaires. In public transport, in supermarkets or at home, the screens surround us, as media to motion pictures. These are therefore made omnipresent. Places displaying heritage, particularly museums, have not escaped this societal change. In various disciplines (museology, history and film studies), research still considering this issue timidly and too often without really talk to each other. Following a symposium held in 2010, where researchers and professionals already met, this edition proposes nine texts to lay some milestones for a crossed approach of uses and practices of moving pictures within the heritage process. It also raises the question of sources for future studies in this field and thus offers several document collections

The Prediction and Validation of Small CDSs Expand the Gene Repertoire of the Smallest Known Eukaryotic Genomes.

The proper prediction of the gene catalogue of an organism is essential to obtain a representative snapshot of its overall lifestyle, especially when it is not amenable to culturing. Microsporidia are obligate intracellular, sometimes hard to culture, eukaryotic parasites known to infect members of every animal phylum. To date, sequencing and annotation of microsporidian genomes have revealed a poor gene complement with highly reduced gene sizes. In the present paper, we investigated whether such gene sizes may have induced biases for the methodologies used for genome annotation, with an emphasis on small coding sequence (CDS) gene prediction. Using better delineated intergenic regions from four Encephalitozoon genomes, we predicted de novo new small CDSs with sizes ranging from 78 to 255 bp (median 168) and corroborated these predictions by RACE-PCR experiments in Encephalitozoon cuniculi. Most of the newly found genes are present in other distantly related microsporidian species, suggesting their biological relevance. The present study provides a better framework for annotating microsporidian genomes and to train and evaluate new computational methods dedicated at detecting ultra-small genes in various organisms

Activation of Toll-like Receptor-2 by Endogenous Matrix Metalloproteinase-2 Modulates Dendritic-Cell-Mediated Inflammatory Responses

Summary: Matrix metalloproteinase-2 (MMP-2) is involved in several physiological mechanisms, including wound healing and tumor progression. We show that MMP-2 directly stimulates dendritic cells (DCs) to both upregulate OX40L on the cell surface and secrete inflammatory cytokines. The mechanism underlying DC activation includes physical association with Toll-like receptor-2 (TLR2), leading to NF-κB activation, OX40L upregulation on DCs, and ensuing TH2 differentiation. Significantly, MMP-2 polarizes T cells toward type 2 responses in vivo, in a TLR2-dependent manner. MMP-2-dependent type 2 polarization may represent a key immune regulatory mechanism for protection against a broad array of disorders, such as inflammatory, infectious, and autoimmune diseases, which can be hijacked by tumors to evade immunity. : Godefroy et al. now demonstrate that matrix metalloproteinase-2 (MMP-2) directly interacts with and activates dendritic cells (DCs) via Toll-like receptor-2. MMP-2-exposed DCs upregulate OX40L, promoting type 2 polarization both in vitro and in vivo. This may represent a key immune regulatory mechanism involved in a variety of inflammatory disorders

In Vitro Antimicrobial Susceptibility Profiles of Gram-Positive Anaerobic Cocci Responsible for Human Invasive Infections

International audienceThe aim of this multicentre study was to determine the in vitro susceptibility to anti-anaerobic antibiotics of Gram-positive anaerobic cocci (GPAC) isolates responsible for invasive infections in humans. A total of 133 GPAC isolates were collected in nine French hospitals from 2016 to 2020. All strains were identified to the species level (MALDI-TOF mass spectrometry, 16S rRNA sequencing). Minimum inhibitory concentrations (MICs) of amoxicillin, piperacillin, cefotaxime, imipenem, clindamycin, vancomycin, linezolid, moxifloxacin, rifampicin, and metronidazole were determined by the reference agar dilution method. Main erm-like genes were detected by PCR. The 133 GPAC isolates were identified as follows: 10 Anaerococcus spp., 49 Finegoldia magna, 33 Parvimonas micra, 30 Peptoniphilus spp., and 11 Peptostreptococcus anaerobius. All isolates were susceptible to imipenem, vancomycin (except 3 P. micra), linezolid and metronidazole. All isolates were susceptible to amoxicillin and piperacillin, except for P. anaerobius (54% and 45% susceptibility only, respectively). MICs of cefotaxime widely varied while activity of rifampicin, and moxifloxacin was also variable. Concerning clindamycin, 31 were categorized as resistant (22 erm(A) subclass erm(TR), 7 erm(B), 1 both genes and 1 negative for tested erm genes) with MICs from 8 to >32 mg/L. Although GPACs are usually susceptible to drugs commonly used for the treatment of anaerobic infections, antimicrobial susceptibility should be evaluated in vitro

Systematic Screening of COVID-19 Disease Based on Chest CT and RT-PCR for Cancer Patients Undergoing Radiation Therapy in a Coronavirus French Hotspot

International audienc

Phylogenetic distribution of the newly predicted small protein-coding genes across 17 sequenced microsporidian species.

<p><i>Left</i>: The HKY85 Maximum Likelihood phylogenetic tree shown here is derived from the small ribosomal RNA-encoding gene. Bootstrap support for each cluster is indicated on the corresponding nodes; only bootstraps greater than 50% are indicated. <i>Right</i>: The presence/absence of the newly identified sCDSs in the corresponding species are denoted by filled and empty circles, respectively. The two grey circles indicate genes that fall within unsequenced regions in the <i>E</i>. <i>intestinalis</i> and <i>E</i>. <i>hellem</i> genomes and whose presence could not be confirmed. Locus names of the new sCDSs (on top) are derived from the <i>E</i>. <i>cuniculi</i> accessions.</p