The hypergroup property and representation of Markov kernels

accepté au "Séminaire de Probabilités"International audienceFor a given orthonormal basis $(f_n)$ on a probability measure space, we want to describe all Markov operators which have the $f_n$ as eigenvectors. We introduce for that what we call the hypergroup property. We study this property in three different cases. On finite sets, this property appears as the dual of the GKS property linked with correlation inequalities in statistical mechanics. The representation theory of groups provides generic examples where these two properties are satisfied, although this group structure is not necessary in general. The hypergroup property also holds for Sturm--Liouville bases associated with log-concave symmetric measures on a compact interval, as stated in Achour--Trimèche's theorem. We give some criteria to relax this symmetry condition in view of extensions to a more general context. In the case of Jacobi polynomials with non-symmetric parameters, the hypergroup property is nothing else than Gasper's theorem. The proof we present is based on a natural interpretation of these polynomials as harmonic functions and is related to analysis on spheres. The proof relies on the representation of the polynomials as the moments of a complex variable

Dematerialization in the AV industry, from boxes to attention. A case study of a newcomer, Tivo

The audiovisual industry's evolution towards the digital era has enabled new actors to enter the market. Tivo Inc has positioned itself as a new comer on the home electronics market by offering both equipment - digital video recorders - and recording services. Although this offer is innovative and evolutive, Tivo's entrance into the AV industry has been highly constrained in that Tivo's interests often conflict with those of established actors. It is Tivo's penetration and dematerialization strategy that we shall analyse in this article; in particular we will examine the services and technologies Tivo has mobilized, the evolution of the valued intermediation functions and the various dimensions of the targeted users. Understanding how these different dimensions combine with one another helps to understand the different attention capturing mechanisms on which this strategic positioning is based

SignalPU: A programming model for DSP applications on parallel and heterogeneous clusters

International audience—The biomedical imagery, the numeric communi-cations, the acoustic signal processing and many others digital signal processing applications (DSP) are present more and more everyday in the numeric world. They process growing data volume which is represented with more and more accuracy, and using complex algorithms with time constraints to satisfying. Con-sequently, a high requirement of computing power characterize them. To satisfy this need, it's inevitable today to use parallel and heterogeneous architectures in order to speed-up the processing, where the best examples are the supercomputers like "Tianhe-2" and "Titan" of the ranking top500. These architectures with their multi-core nodes supported by many-core accelerators offer a good response to this problem, but they are still hard to program in order to make performance because of lot of things like synchronization, the memory management, the hardware specifications . . . In the present work, we propose a high level programming model to implement easily and efficiently digital signal processing applications on heterogeneous clusters

Task migration of DSP application specified with a DFG and implemented with the BSP computing model on a CPU-GPU cluster

International audienceNowadays computer applications are becoming heavier and require, at the same time, real-time results. The Heterogeneous clusters with their computing power represent a good solution to this request. However, it is possible that during the execution, a computing element of the cluster becomes defaulting, needs maintenance, or that the load needs to be re-balanced. . . In this paper, we propose a migration strategy for relocating the execution of a task to another computing element. In particular, we are interested in remap nodes of Data Flow Graph (DFG), representing Digital Signal Processing (DSP) application, onto heterogeneous (CPU-GPU) clusters while keeping up the flow of data and minimizing the temporal perturbation. For our approach, we give a lower bound for the flow of data after the migration and, validate it by the real-time construction of visual saliency map from video input

Inducible expression of beta defensins by human respiratory epithelial cells exposed to Aspergillus fumigatus organisms

<p>Abstract</p> <p>Background</p> <p><it>Aspergillus fumigatus</it>, a saprophytic mould, is responsible for life-threatening, invasive pulmonary diseases in immunocompromised hosts. The role of the airway epithelium involves a complex interaction with the inhaled pathogen. Antimicrobial peptides with direct antifungal and chemotactic activities may boost antifungal immune response.</p> <p>Results</p> <p>The inducible expression of defensins by human bronchial epithelial 16HBE cells and A549 pneumocyte cells exposed to <it>A. fumigatus </it>was investigated. Using RT-PCR and real time PCR, we showed an activation of hBD2 and hBD9 defensin genes: the expression was higher in cells exposed to swollen conidia (SC), compared to resting conidia (RC) or hyphal fragments (HF). The kinetics of defensin expression was different for each one, evoking a putative distinct function for each investigated defensin. The decrease of defensin expression in the presence of heat-inactivated serum indicated a possible link between defensins and the proteins of the host complement system. The presence of defensin peptide hBD2 was revealed using immunofluorescence that showed a punctual cytoplasmic and perinuclear staining. Quantification of the cells stained with anti hBD2 antibody demonstrated that SC induced a greater number of cells that synthesized hBD2, compared to RC or HF. Labelling of the cells with anti-hBD-2 antibody showed a positive immunofluorescence signal around RC or SC in contrast to HF. This suggests co-localisation of hBD2 and digested conidia. The HBD2 level was highest in the supernatants of cells exposed to SC, as was determined by sandwich ELISA. Experiments using neutralising anti-interleukine-1β antibody reflect the autocrine mechanism of defensin expression induced by SC. Investigation of defensin expression at transcriptional and post-transcriptional levels demonstrated the requirement of transcription as well as new protein synthesis during <it>A. fumigatus </it>defensin induction. Finally, induced defensin expression in primary culture of human respiratory cells exposed to <it>A. fumigatus </it>points to the biological significance of described phenomena.</p> <p>Conclusion</p> <p>Our findings provide evidence that respiratory epithelium might play an important role in the immune response during <it>Aspergillus </it>infection. Understanding the mechanisms of regulation of defensin expression may thus lead to new approaches that could enhance expression of antimicrobial peptides for potential therapeutic use during aspergillosis treatment.</p

Characterization of a new simian immunodeficiency virus strain in a naturally infected Pan troglodytes troglodytes chimpanzee with AIDS related symptoms

<p>Abstract</p> <p>Background</p> <p>Data on the evolution of natural SIV infection in chimpanzees (SIVcpz) and on the impact of SIV on local ape populations are only available for Eastern African chimpanzee subspecies (<it>Pan troglodytes schweinfurthii</it>), and no data exist for Central chimpanzees (<it>Pan troglodytes troglodytes</it>), the natural reservoir of the ancestors of HIV-1 in humans. Here, we report a case of naturally-acquired SIVcpz infection in a <it>P.t.troglodytes </it>chimpanzee with clinical and biological data and analysis of viral evolution over the course of infection.</p> <p>Results</p> <p>A male chimpanzee (Cam155), 1.5 years, was seized in southern Cameroon in November 2003 and screened SIV positive during quarantine. Clinical follow-up and biological analyses have been performed for 7 years and showed a significant decline of CD4 counts (1,380 cells/mm³in 2004 vs 287 in 2009), a severe thrombocytopenia (130,000 cells/mm³in 2004 vs 5,000 cells/mm³in 2009), a weight loss of 21.8% from August 2009 to January 2010 (16 to 12.5 kg) and frequent periods of infections with diverse pathogens.</p> <p>DNA from PBMC, leftover from clinical follow-up samples collected in 2004 and 2009, was used to amplify overlapping fragments and sequence two full-length SIVcpz<it>Ptt</it>-Cam155 genomes. SIVcpz<it>Ptt</it>-Cam155 was phylogenetically related to other SIVcpz<it>Ptt </it>from Cameroon (SIVcpz<it>Ptt</it>-Cam13) and Gabon (SIVcpz<it>Ptt</it>-Gab1). Ten molecular clones 5 years apart, spanning the V1V4 gp120 <it>env </it>region (1,100 bp), were obtained. Analyses of the <it>env </it>region showed positive selection (dN-dS >0), intra-host length variation and extensive amino acid diversity between clones, greater in 2009. Over 5 years, N-glycosylation site frequency significantly increased (p < 0.0001).</p> <p>Conclusions</p> <p>Here, we describe for the first time the clinical history and viral evolution of a naturally SIV infected <it>P.t.troglodytes </it>chimpanzee. The findings show an increasing viral diversity over time and suggest clinical progression to an AIDS-like disease, showing that SIVcpz can be pathogenic in its host, as previously described in <it>P.t.schweinfurthii</it>. Although studying the impact of SIV infection in wild apes is difficult, efforts should be made to better characterize the pathogenicity of the ancestors of HIV-1 in their natural host and to find out whether SIV infection also plays a role in ape population decline.</p

Reuse of medical face masks in domestic and community settings without sacrificing safety: Ecological and economical lessons from the Covid-19 pandemic

The need for personal protective equipment increased exponentially in response to the Covid-19 pandemic. To cope with the mask shortage during springtime 2020, a French consortium was created to find ways to reuse medical and respiratory masks in healthcare departments. The consortium addressed the complex context of the balance between cleaning medical masks in a way that maintains their safety and functionality for reuse, with the environmental advantage to manage medical disposable waste despite the current mask designation as single-use by the regulatory frameworks. We report a Workflow that provides a quantitative basis to determine the safety and efficacy of a medical mask that is decontaminated for reuse. The type IIR polypropylene medical masks can be washed up to 10 times, washed 5 times and autoclaved 5 times, or washed then sterilized with radiations or ethylene oxide, without any degradation of their filtration or breathability properties. There is loss of the antiprojection properties. The Workflow rendered the medical masks to comply to the AFNOR S76-001 standard as “type 1 non-sanitory usage masks”. This qualification gives a legal status to the Workflow-treated masks and allows recommendation for the reuse of washed medical masks by the general population, with the significant public health advantage of providing better protection than cloth-tissue masks. Additionally, such a legal status provides a basis to perform a clinical trial to test the masks in real conditions, with full compliance with EN 14683 norm, for collective reuse. The rational reuse of medical mask and their end-of-life management is critical, particularly in pandemic periods when decisive turns can be taken. The reuse of masks in the general population, in industries, or in hospitals (but not for surgery) has significant advantages for the management of waste without degrading the safety of individuals wearing reused masks

Mise en oeuvre, modélisation et comparaison de trois systèmes d'amplification de puissance sous vide utilisant des plasmas sous striction magnétique.

This work proposes a methodology for the analysis of the overall operation of HPP system and a theoretical and experimental study of a Plasma Opening Switch, the LL schema and the Flux Compression. An analytical modelling of the operation phases is given in order to evaluate their efficiency and compare them. Based on a development of the Hall MHD and a model of the initial plasma distribution, the POS study sets out the different penetration modes of B during the conduction phase and the transition towards the opening physics. The analysis of the LL tests shows specificities (B configuration, losses) and leads towards a complete electrical modelling. The use of the analytical model for the study of CF tests reveals the flow of current in the plasma thickness et its impact on the scheme efficiency. Finally, the performances of future machines are expressed into specific characteristics of the schemes and compared to the experience in order to evaluate their viability and the forecoming work.Ce travail propose une méthodologie pour l'analyse du fonctionnement global d'un système HPP ainsi qu'une étude théorique et expérimentale des systèmes commutateur à plasma (POS), schéma LL et Compression de Flux. Une modélisation analytique des phases de fonctionnement est donnée pour évaluer leur rendement et les comparer. En s'appuyant sur un développement de la MHD Hall et sur un modèle de distribution du plasma, l'étude POS expose les modes de pénétration de B pendant la conduction et la transition vers la physique de l'ouverture. L'analyse des essais LL montre des spécificités (configuration de B, pertes) et conduit à un modèle électrique complet. L'usage du modèle analytique pour l'étude des essais CF révèle la circulation du courant dans l'épaisseur du plasma et son impact sur l'efficacité du schéma. Enfin, les performances des futures machines sont traduites en caractéristiques spécifiques aux schémas et comparées à l'expérience pour aborder leur viabilité et les travaux à venir

Mise en oeuvre, modélisation et comparaison de trois systèmes d'amplification de puissance sous vide utilisant des plasmas sous striction magnétique

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF