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Search Results: 1 - 10 of 231726 matches for " Fran?ois-Régis Jasnot "
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Magnetotransport in quantum cascade detectors: analyzing the current under illumination
Jasnot Franois-Régis,ré-Laperne Nicolas,de Vaulchier Louis-Anne,Guldner Yves
Nanoscale Research Letters , 2011,
Abstract: Photocurrent measurements have been performed on a quantum cascade detector structure under strong magnetic field applied parallel to the growth axis. The photocurrent shows oscillations as a function of B. In order to describe that behavior, we have developed a rate equation model. The interpretation of the experimental data supports the idea that an elastic scattering contribution plays a central role in the behavior of those structures. We present a calculation of electron lifetime versus magnetic field which suggests that impurities scattering in the active region is the limiting factor. These experiments lead to a better understanding of these complex structures and give key parameters to optimize them further.
Direct surface cyclotron resonance terahertz emission from a quantum cascade structure
Franois-Régis Jasnot,Louis-Anne De Vaulchier,Yves Guldner,Gérald Bastard,Angela Vasanelli,Christophe Manquest,Carlo Sirtori,Mattias Beck,r?me Faist
Physics , 2012, DOI: 10.1063/1.3692572
Abstract: A strong magnetic field applied along the growth direction of a semiconductor quantum well gives rise to a spectrum of discrete energy states, the Landau levels. By combining quantum engineering of a quantum cascade structure with a static magnetic field, we can selectively inject electrons into the excited Landau level of a quantum well and realize a tunable surface emitting device based on cyclotron emission. By applying the appropriate magnetic field between 0 and 12 T, we demonstrate emission from a single device over a wide range of frequencies (1-2 THz and 3-5 THz).
Antelop : an industrial platform for linguistic processing Antelope : une plate-forme industrielle de traitement linguistique
Franois-Régis Chaumartin
Traitement Automatique des Langues , 2009,
Abstract: The Antelope linguistic platform, inspired by Meaning-Text Theory, targets the syntactic and semantic analysis of texts, and can handle large corpora. Antelope integrates several pre-existing (parsing) components as well as broad-coverage linguistic data originating from various sources. Efforts towards integration of all components nonetheless make for a homogeneous platform. Our direct contribution deals with components for semantic analysis, and the formalization of a unified text analysis model. This paper introduces the platform and compares it with state-of-the-art projects. It offers to the NLP community a feedback from a software company, by underlining the architectural measures that should be taken to ensure that such complex software remains maintainable.
On genocide, economic reasons vs. ethnic passion
Ballet Jér?me,Bazin Damien,Franois-Régis Mahieu
Panoeconomicus , 2008, DOI: 10.2298/pan0804485b
Abstract: The traditional vision of genocide is exogenous. In this framework, ethnics have a real sense. The economic approach of conflicts has expressed slight differences in the relation between ethnics and conflicts. However it does not reject this explanation. Here we propose an alternative approach, an endogenous vision of genocide. Genocide appears in society where social capital plays a major role in solidarities. But social capital is a weak asset in the individual portfolio. Economic and social shocks may have impacts on the assets structure and may produce conflicts such as genocide. In this new framework, policy makers may have to adopt prudential rules. .
A la recherche du développement socialement durable: concepts fondamentaux et principes de base
r?me Ballet,Franois-Régis Mahieu,Jean-Luc Dubois
Développement Durable et Territoires , 2004,
Abstract: Le développement est considéré comme durable lorsqu’il permet aux générations actuelles de satisfaire à leurs besoins sans compromettre la capacité des générations futures à satisfaire les leurs. Il faut pour cela que les générations futures détiennent au moins autant de ressources, sous la forme de capital ou de potentialités diverses, que la génération actuelle. Lorsqu’on considère la dimension sociale du développement durable, se pose alors la question du transfert des acquis ou potentialités d’une génération à l’autre. Ces potentialités prennent de multiples formes: capital humain (éducation, santé), capital social (liens sociaux), capacité à utiliser les potentialités disponibles, etc. Plus généralement, la durabilité sociale du développement demande d’aborder les conditions d’une transmission équitable des "capacités à faire et à être" (plus simplement "capabilités") d’une génération à l’autre. On attend donc d’un développement socialement durable qu’il protège les potentialités, renforce les capacités d’une génération donnée, et facilite leur transfert à la génération suivante. Cela implique d’examiner ce qui empêche la constitution de potentialités (trappes à pauvreté), l’amélioration des capacités (exclusion sociale et vulnérabilité) et la transmission inter-générationnelle (inégalités). Dès lors, dans le cadre d’une éthique de la responsabilité, des principes de précaution sociale adéquats pourraient guider l’élaboration des politiques publiques. Sustainable development allows the current generation to satisfy its needs without compromising the capacity of future generations to satisfy theirs. This implies that future generations should have in hand at least as many resources, in terms of capital or various potentialities, than the current generation. The social dimension of sustainable development raises the issue of transmitting social assets and potentialities from one generation to the other. These include human capital (education, health), social capital (relationships) as well as any capacity to use in an appropriate way these potentialities. More generally, social sustainability focuses on the conditions for an equitable transmission of capabilities from one generation to the others. It is expected from a socially sustainable development to protect the social potentiality, to improve the person’s capability and to facilitate their transfer from one generation to the next. This implies reviewing the causes that prevent the creation of potentiality (poverty trap), the promotion of capability (social exclusion and vulnerability) and the in
Treatment of Nasopharyngeal Carcinoma Cells with the Histone-Deacetylase Inhibitor Abexinostat: Cooperative Effects with Cis-platin and Radiotherapy on Patient-Derived Xenografts
Mélanie Gressette, Benjamin Vérillaud, Anne-Sophie Jimenez-Pailhès, Hélène Lelièvre, Kwok-Wai Lo, Franois-Régis Ferrand, Charles-Henry Gattolliat, Anne Jacquet-Bescond, Laurence Kraus-Berthier, Stéphane Depil, Pierre Busson
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091325
Abstract: EBV-related nasopharyngeal carcinomas (NPCs) still raise serious therapeutic problems. The therapeutic potential of the histone-deacetylase (HDAC) inhibitor Abexinostat was investigated using 5 preclinical NPC models including 2 patient-derived xenografts (C15 and C17). The cytotoxicity of Abexinostat used either alone or in combination with cis-platin or irradiation was assessed in vitro by MTT and clonogenic assays using 2 EBV-negative (CNE1 and HONE1) and 3 EBV-positive NPC models (C15, C17 and C666-1). Subsequently, the 3 EBV-positive models were used under the form of xenografts to assess the impact of systemic treatments by Abexinostat or combinations of Abexinostat with cis-platin or irradiation. Several cell proteins known to be affected by HDAC inhibitors and the small viral non-coding RNA EBER1 were investigated in the treated tumors. Synergistic cytotoxic effects of Abexinostat combined with cis-platin or irradiation were demonstrated in vitro for each NPC model. When using xenografts, Abexinostat by itself (12.5 mg/kg, BID, 4 days a week for 3 weeks) had significant anti-tumor effects against C17. Cooperative effects with cis-platin (2 mg/kg, IP, at days 3, 10 and 17) and irradiation (1Gy) were observed for the C15 and C17 xenografts. Simultaneously two types of biological alterations were induced in the tumor tissue, especially in the C17 model: a depletion of the DNA-repair protein RAD51 and a stronger in situ detection of the small viral RNA EBER1. Overall, these results support implementation of phase I/II clinical trials of Abexinostat for the treatment of NPC. A depletion of RAD51 is likely to contribute to the cooperation of Abexinostat with DNA damaging agents. Reduction of RAD51 combined to enhanced detection of EBER 1 might be helpful for early assessment of tumor response.
COSIMA-Rosetta calibration for in-situ characterization of 67P/Churyumov-Gerasimenko cometary inorganic compounds
Harald Krüger,Thomas Stephan,Cécile Engrand,Christelle Briois,Sandra Siljestr?m,Sihane Merouane,Donia Baklouti,Henning Fischer,Nicolas Fray,Klaus Hornung,Harry Lehto,Franois-Régis Orthous-Daunay,Jouni Ryn?,Rita Schulz,Johan Silen,Laurent Thirkell,Mario Trieloff,Martin Hilchenbach
Physics , 2015, DOI: 10.1016/j.pss.2015.05.005
Abstract: COSIMA (COmetary Secondary Ion Mass Analyser) is a time-of-flight secondary ion mass spectrometer (TOF-SIMS) on board the Rosetta space mission. COSIMA has been designed to measure the composition of cometary dust grains. It has a mass resolution m/{\Delta}m of 1400 at mass 100 u, thus enabling the discrimination of inorganic mass peaks from organic ones in the mass spectra. We have evaluated the identification capabilities of the reference model of COSIMA for inorganic compounds using a suite of terrestrial minerals that are relevant for cometary science. Ground calibration demonstrated that the performances of the flight model were similar to that of the reference model. The list of minerals used in this study was chosen based on the mineralogy of meteorites, interplanetary dust particles and Stardust samples. It contains anhydrous and hydrous ferromagnesian silicates, refractory silicates and oxides (present in meteoritic Ca-Al-rich inclusions), carbonates, and Fe-Ni sulfides. From the analyses of these minerals, we have calculated relative sensitivity factors for a suite of major and minor elements in order to provide a basis for element quantification for the possible identification of major mineral classes present in the cometary grains.
Mathematical model for coupling a quasi-unidimensional perfect flow
Régis Msallam,Franois Dubois
Mathematics , 2010,
Abstract: Nonlinear acoustics of wind instruments conducts to study unidimensional fluid flows. From physically relevant approximations that are modelized with the thin layer Navier Stokes equations, we propose a coupled model where perfect fluid flow is described by the Euler equations of gas dynamics and viscous and thermal boundary layer is modelized by a linear equation. We describe numerical discretization, validate the associated software by comparison with analytical solutions and consider musical application of strongly nonlinear waves in the trombone.
Deacetylation of H4-K16Ac and heterochromatin assembly in senescence
Kévin Contrepois, Jean-Yves Thuret, Régis Courbeyrette, Franois Fenaille, Carl Mann
Epigenetics & Chromatin , 2012, DOI: 10.1186/1756-8935-5-15
Abstract: We found that both deacetylation of H4-K16Ac and expression of HMGA1/2 can contribute to DNA compaction during senescence. SIRT2, an NAD-dependent class III histone deacetylase, contributes to H4-K16Ac deacetylation and DNA compaction in human fibroblast cell lines that assemble striking senescence-associated heterochromatin foci (SAHFs). Decreased H4-K16Ac was observed in both replicative and oncogene-induced senescence of these cells. In contrast, this mechanism was inoperative in a fibroblast cell line that did not assemble extensive heterochromatin during senescence. Treatment of senescent cells with trichostatin A, a class I/II histone deacetylase inhibitor, also induced rapid and reversible decondensation of SAHFs. Inhibition of DNA compaction did not significantly affect the stability of the senescent state.Variable DNA compaction observed during senescence is explained in part by cell-type specific regulation of H4 deacetylation and HMGA1/2 expression. Deacetylation of H4-K16Ac during senescence may explain reported decreases in this mark during mammalian aging and in cancer cells.Genomic DNA in eukaryotes is packaged into chromatin. The histones and non-histone proteins of chromatin compact the DNA and govern its accessibility to enzymes during transcription, replication, repair and recombination. Poorly transcribed regions of the genome are typically found in highly compacted DNA as heterochromatin, whereas transcribed sequences are found in the more accessible euchromatin [1]. Post-translational modifications of histones represent an important mechanism modulating the accessibility of chromatin and contributing to the recruitment of other proteins to chromatin [2]. Histones are extensively modified principally by acetylation, methylation, ubiquitylation, and phosphorylation. Euchromatin is enriched in histones acetylated at lysine residues. Acetylation of H4-K16 plays a particularly important, evolutionarily conserved role in regulating chromatin compacti
Constitutive Expression of TNF-Related Activation-Induced Cytokine (TRANCE)/Receptor Activating NF-κB Ligand (RANK)-L by Rat Plasmacytoid Dendritic Cells
Thomas Anjubault,r?me Martin, Franois-Xavier Hubert, Camille Chauvin, Dominique Heymann, Régis Josien
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033713
Abstract: Plasmacytoid dendritic cells (pDCs) are a subset of DCs whose major function relies on their capacity to produce large amount of type I IFN upon stimulation via TLR 7 and 9. This function is evolutionary conserved and place pDC in critical position in the innate immune response to virus. Here we show that rat pDC constitutively express TNF-related activation-induced cytokine (TRANCE) also known as Receptor-activating NF-κB ligand (RANKL). TRANCE/RANKL is a member of the TNF superfamily which plays a central role in osteoclastogenesis through its interaction with its receptor RANK. TRANCE/RANK interaction are also involved in lymphoid organogenesis as well as T cell/DC cross talk. Unlike conventional DC, rat CD4high pDC were shown to constitutively express TRANCE/RANKL both at the mRNA and the surface protein level. TRANCE/RANKL was also induced on the CD4low subsets of pDC following activation by CpG. The secreted form of TRANCE/RANKL was also produced by rat pDC. Of note, levels of mRNA, surface and secreted TRANCE/RANKL expression were similar to that observed for activated T cells. TRANCE/RANKL expression was found on pDC in all lymphoid organs as well blood and BM with a maximum expression in mesenteric lymph nodes. Despite this TRANCE/RANKL expression, we were unable to demonstrate in vitro osteoclastogenesis activity for rat pDC. Taken together, these data identifies pDC as novel source of TRANCE/RANKL in the immune system.
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