1,139 research outputs found

    Holomorphic extension of the de Gennes function

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    This note is devoted to prove that the de Gennes function has a holomorphic extension on a strip containing the real axis

    Magnetic WKB Constructions

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    This paper is devoted to the semiclassical magnetic Laplacian. Until now WKB expansions for the eigenfunctions were only established in presence of a non-zero electric potential. Here we tackle the pure magnetic case. Thanks to Feynman-Hellmann type formulas and coherent states decomposition, we develop here a magnetic Born-Oppenheimer theory. Exploiting the multiple scales of the problem, we are led to solve an effective eikonal equation in pure magnetic cases and to obtain WKB expansions. We also investigate explicit examples for which we can improve our general theorem: global WKB expansions, quasi-optimal estimates of Agmon and upper bound of the tunelling effect (in symmetric cases). We also apply our strategy to get more accurate descriptions of the eigenvalues and eigenfunctions in a wide range of situations analyzed in the last two decades

    Cross-validating administrative and survey datasets through microsimulation and the assessment of a tax reform in Luxembourg

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    Using EUROMOD, we cross-validate two types of micro-data presently available in the Grand-Duchy of Luxembourg, administrative data on one hand and survey data on the other hand. While administrative data, extracted from the recently implemented Social Security Data Warehouse, contain information of the whole population of Luxembourg (449,000 observations) in 2003, survey data, extracted from the Luxembourg household panel PSELL3/EU-SILC for 2004 (incomes from 2003), is a representative sample of around 3,600 private households (9,800 individuals) living in Luxembourg with detailed information on incomes, household structure and other socio-economic dimensions. As a concrete application of this cross-validation, we analyze the 2001-2002 tax reform in Luxembourg. The main aspects of this reform are the reduction of the number of the tax brackets and the fall of the maximal marginal tax rate (from 46% in 2000 to 42% in 2001 and to 38% in 2002). The distributional effects of the tax reform are measured in terms of losers and winners, change in inequalities and poverty rates. The results issued from different types of input data are compared for cross-validation and allow us to emphasize methodological difficulties as well as to underline the advantages and limitations of each dataset.EUROMOD ; Microsimulation ; Tax reform ; Validation

    Benchmarking benchmarks: introducing new automatic indicators for benchmarking Spoken Language Understanding corpora

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    International audienceEmpirical evaluation is nowadays the main evaluation paradigm in Natural Language Processing for assessing the relevance of a new machine-learning based model. If large corpora are available for tasks such as Automatic Speech Recognition , this is not the case for other tasks such as Spoken Language Understanding (SLU), consisting in translating spoken transcriptions into a formal representation often based on semantic frames. Corpora such as ATIS or SNIPS are widely used to compare systems, however differences in performance among systems are often very small, not statistically significant , and can be produced by biases in the data collection or the annotation scheme, as we presented on the ATIS corpus ("Is ATIS too shallow?, IS2018"). We propose in this study a new methodology for assessing the relevance of an SLU corpus. We claim that only taking into account systems performance does not provide enough insight about what is covered by current state-of-the-art models and what is left to be done. We apply our methodology on a set of 4 SLU systems and 5 benchmark corpora (ATIS, SNIPS, M2M, MEDIA) and automatically produce several indicators assessing the relevance (or not) of each corpus for benchmarking SLU models

    Electrical properties and reactivity under air–CO flows of composite systems based on ceria coated carbon nanotubes

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    Nanocomposite systems of ceria nanoparticles and Double Walled Carbon Nanotubes (DWNTs) coated with nanoceria (nCeO2) were elaborated using a classical sol gel method. Three samples noted as [nCeO2 + xDWNTs] with variable weight fractions x = 0, 5 and 15 wt.% of DWNTs were obtained. The samples were characterized by Xray diffraction and electron microscopy. The electrical conductivity of [nCeO2 + xDWNTs] compacted pellets systems was determined from electrical impedance spectrometry, under air, between 120 and 400 °C. In this temperature range, all samples were semiconducting with a weak variation of activation energy. However, the conductivity strongly increased with the weight fraction of ceria coated carbon nanotubes. Finally, the solid–gas interactions between air–CO flows and these systems were studied as a function of time and temperature, by means of Fourier transform infrared (FTIR) spectroscopy. The oxidation kinetics of CO into CO2 was analyzed from the evolutions of FTIR absorption band intensities. As the carbon nanotube fraction x increased, the conversion efficiency was strongly improved

    Semiclassical tunneling and magnetic flux effects on the circle

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    International audienceThis paper is devoted to semiclassical tunneling estimates induced on the circle by a double well electric potential in the case when a magnetic field is added. When the two electric wells are connected by two geodesics for the Agmon distance, we highlight an oscillating factor (related to the circulation of the magnetic field) in the splitting estimate of the first two eigenvalues

    Bio-informatique pour la génomique et le diagnostic des maladies infectieuses

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    Le séquençage du génome d’un microorganisme est un jalon important dans l’étude de sa biologie. Quel que soit cet organisme, les outils bio-informatiques nécessaires pour comprendre son génome et le comparer aux autres génomes séquencés seront similaires. Dans cette thèse, l’ADN génomique de parasites et de virus est mis à profit afin de mieux comprendre ces microorganismes. Dans un premier temps, le parasite protozoaire Leishmania est étudié par transcriptomique et par génomique comparative afin de mieux comprendre son infectivité, sa résistance aux antiparasitaires et son mode de vie dimorphique. Ce parasite alterne entre le stade flagellé (promastigote) et le stade intracellulaire aflagellé (amastigote). Afin de faciliter l’analyse par biopuces du transcriptome de Leishmania, un système de gestion et d’analyse de données de biopuces a été conçu. Quatre études utilisant ce système sont présentées sommairement et leurs implications sont discutées. Deuxièmement, le génome de l’espèce Leishmania (sauroleishmania) tarentolae, qui n’est pas pathogène pour l’humain, a été séquencé et comparé à trois espèces infectant l’homme. Cette étude a montré que, même si peu de gènes différencient les espèces, L. tarentolae possède moins de gènes associés au stade amastigote que les autres espèces. Deux familles de gènes ont été trouvées en nombre de copies élevées chez L. tarentolae : GP63 et PSA31C. Ces résultats permettent une meilleure compréhension de la biologie de L. tarentolae et de la virulence des autres espèces de Leishmania. Dans un deuxième temps, les séquences des génomes de virus respiratoires disponibles dans les bases de données publiques ont été analysées pour créer un test diagnostique permettant la détection et l’identification de 25 types de virus respiratoires, dont la grippe A (H1N1) responsable de la pandémie de 2009 et la grippe aviaire A (H5N1). Le test a été validé avec des échantillons de laboratoire et avec des échantillons cliniques. Même si l’étude du parasite Leishmania était indépendante de celle des virus respiratoires, les approches utilisées pour ces deux projets étaient similaires. Ainsi, la bio-informatique est un outil essentiel en microbiologie, car elle est indispensable pour résoudre des problèmes de diverses natures chez des organismes différents.Sequencing a genome is a milestone in the study of an organism. Bioinformatics allow both to better understand single organisms and to compare them to related species through comparative genomics. This thesis centers on the idea that genome sequence of parasites and viruses can be used in various ways to better understand these microorganisms. Transcriptomics and comparative genomics were used to study the protozoan parasite Leishmania in order to better understand its virulence, its resistance to antiparasitic drugs, and its dimorphic life-cycle, which includes a flagellated free form named promastigote and an aflagellate intracellular form named amastigote. In order to study gene expression in Leishmania, an integrated management and analysis system was created, along with protocols designed for Leishmania microarrays analysis. Four studies using this system are briefly described. In another study, the genome of Leishmania (sauroleishmania) tarentolae, a lizard parasite, was sequenced and compared to human pathogenic Leishmania species. This study showed little difference between the Leishmania species, although L. tarentolae seems to contain less genes associated to the amastigote life-cycle, including the amastin gene. Two gene families were highly expanded in L. tarentolae: the surface metalloprotease GP63 and the promastigote antigen protein PSA31C. These results provide a better understanding of L. tarentolae biology and give insights on the genes involved in virulence in pathogenic Leishmania species. The second part of this thesis concerns the creation of a molecular diagnostic assay for the detection and identification of 25 respiratory virus types, including the influenza A/H1N1 pandemic strain and the avian influenza A/H5N1 strain. This assay was created by analyzing genome sequences available from public repositories and it was afterwards tested on laboratory and clinical virus strains. Although Leishmania and respiratory viruses are distantly related, the approaches used in both projects were similar. Thus, bioinformatics is an essential and ubiquitous science that allows to solve problems in different areas (“omics”) of biology

    A Decidable Characterization of a Graphical Pi-calculus with Iterators

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    This paper presents the Pi-graphs, a visual paradigm for the modelling and verification of mobile systems. The language is a graphical variant of the Pi-calculus with iterators to express non-terminating behaviors. The operational semantics of Pi-graphs use ground notions of labelled transition and bisimulation, which means standard verification techniques can be applied. We show that bisimilarity is decidable for the proposed semantics, a result obtained thanks to an original notion of causal clock as well as the automatic garbage collection of unused names.Comment: In Proceedings INFINITY 2010, arXiv:1010.611
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