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La compréhension des inégalités de genre, manifestes dans le milieu de l’art contemporain français, peut s’affiner au prisme d’une variable complémentaire : celle de l’âge / génération du plasticien. Le présent article, à travers l’étude des divers canaux de légitimation du champ artistique et du marché, dévoile que le vieillissement accentue les inégalités de représentation pour les femmes artistes les plus âgées alors qu’au contraire, ces écarts sont moins marqués pour les plus jeunes. The understanding of manifest gender inequalities in French contemporary art can be deepened through the prism of a complementary variable: that of the artist’s age / generation. This article, through the study of the various channels of legitimization that constitute the artistic field and the market, reveals that aging increases inequalities in representation for older female artists, while on the contrary, these gaps tend to diminish for younger artists

Thermoacoustic systems can exhibit self-excited instabilities of two nature, namely cavity modes or intrinsic thermoacoustic (ITA) modes. In heavy-duty land-based gas turbines with can-annular combustors, the cross-talk between cans causes the cavity modes of various azimuthal order to create clusters, i.e., ensembles of modes with close frequencies. Similarly, in systems exhibiting rotational symmetry, ITA modes also have the peculiar behavior of forming clusters. In the present study, we investigate how such clusters interplay when they are located in the same frequency range. We first consider a simple Rijke tube configuration and derive a general analytical low-order network model using only dimensionless numbers. We investigate the trajectories of the eigenmodes when changing the downstream length and the flame position. In particular, we show that ITA and acoustic modes can switch nature and their trajectories are strongly influenced by the presence of exceptional points. We then study a generic can-annular combustor. We show that such configuration can be approximated by an equivalent Rijke tube. We demonstrate that, in the absence of mean flow, the eigenvalues of the system necessarily lie on specific trajectories imposed by the upstream conditions.

Low-order network models, commonly used to assess the thermo-acoustic stability of combustors, can be cast in a linear, time-continuous state-space representation. A standard linear eigenvalue problem for the system modes results, which can be solved in a robust and efficient manner. To represent the linear dynamics of any time-invariant flame in the state-space framework, this study presents an approximation of the distributed time-delayed flame response to acoustic velocity perturbations based on a spatially discretized propagation equation (PE). We derive the rational flame transfer function of a first-order-upwind-PE state-space model and discuss its relation to the Tustin approximation of flame transfer functions. For an exemplary discrete finite impulse response of a flame, a third-order-upwind-PE state-space model is shown to match the discrete flame frequency response with comparable accuracy as a rational approximation found by non-linear optimization. The numerical dissipation introduced by discretization of the PE ensures zero gain above the Nyquist frequency of the underlying discrete flame impulse response. Finally, we apply the PE state-space flame model to a generic Rijke tube and show that the predicted thermo-acoustic modes agree well with results obtained from a classical non-linearly optimized rational approximation of the frequency response function of the flame.

Network authors: Portugal - Raquel Guiomar, Pedro Pechirra, National Influenza Reference Laboratory, Infectious Diseases Department, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal Background: The 2018/2019 influenza season in the WHO European Region was dominated by influenza A (H1N1)pdm09 and (H3N2) viruses, with very few influenza B viruses detected. Methods: Countries in the European Region reported virus characterization data to The European Surveillance System for weeks 40/2018 to 20/2019. These virus antigenic and genetic characterization and haemagglutinin (HA) sequence data were analysed to describe and assess circulating viruses relative to the 2018/2019 vaccine virus components for the northern hemisphere. Results: Thirty countries reported 4776 viruses characterized genetically and 3311 viruses antigenically. All genetically characterized A(H1N1)pdm09 viruses fell in subclade 6B.1A, of which 90% carried the amino acid substitution S183P in the HA gene. Antigenic data indicated that circulating A(H1N1)pdm09 viruses were similar to the 2018/2019 vaccine virus. Genetic data showed that A(H3N2) viruses mostly fell in clade 3C.2a (75%) and 90% of which were subclade 3C.2a1b. A lower proportion fell in clade 3C.3a (23%) and were antigenically distinct from the vaccine virus. All B/Victoria viruses belonged to clade 1A; 30% carried a double amino acid deletion in HA and were genetically and antigenically similar to the vaccine virus component, while 55% carried a triple amino acid deletion or no deletion in HA; these were antigenically distinct from each other and from the vaccine component. All B/Yamagata viruses belonged to clade 3 and were antigenically similar to the virus component in the quadrivalent vaccine for 2018/2019. Conclusions: A simultaneous circulation of genetically and antigenically diverse A(H3N2) and B/Victoria viruses was observed and represented a challenge to vaccine strain selection. Highlights: Co-circulation of different clades/subclades of influenza A viruses in 2018/2019 in the Region; Most circulating A(H1N1)pdm09 viruses (6B.1A) carried S183P in hemagglutinin; Genetically heterogeneous A(H3N2) viruses, with co-circulation of clades 3C.2a and 3C.3a; Antigenically distinct A(H3N2) clade 3C.3a viruses were increasingly detected until 02/2019 and then decreased; Co-circulation of genetically and antigenically diverse A(H3N2) strains challenges vaccine strain selection. info:eu-repo/semantics/publishedVersion

Background Reliable testing for SARS-CoV-2 is key for the management of the COVID-19 pandemic. Aim We estimate diagnostic accuracy for nucleic acid and antibody tests 5 months into the COVID-19 pandemic, and compare with manufacturer-reported accuracy. Methods We reviewed the clinical performance of SARS-CoV-2 nucleic acid and antibody tests based on 93,757 test results from 151 published studies and 20,205 new test results from 12 countries in the European Union and European Economic Area (EU/EEA). Results Pooling the results and considering only results with 95% confidence interval width ≤ 5%, we found four nucleic acid tests, including one point-of-care test and three antibody tests, with a clinical sensitivity ≥ 95% for at least one target population (hospitalised, mild or asymptomatic, or unknown). Nine nucleic acid tests and 25 antibody tests, 12 of them point-of-care tests, had a clinical specificity of ≥ 98%. Three antibody tests achieved both thresholds. Evidence for nucleic acid point-of-care tests remains scarce at present, and sensitivity varied substantially. Study heterogeneity was low for eight of 14 sensitivity and 68 of 84 specificity results with confidence interval width ≤ 5%, and lower for nucleic acid tests than antibody tests. Manufacturer-reported clinical performance was significantly higher than independently assessed in 11 of 32 and four of 34 cases, respectively, for sensitivity and specificity, indicating a need for improvement in this area. Conclusion Continuous monitoring of clinical performance within more clearly defined target populations is needed.

International audience; The aim of the present work is to contribute to a better understanding of the physical mechanism causing the low frequency oscillations of the Shock Wave Boundary-Layer Interaction (SWBLI) by analyzing data from highly resolved unsteady numerical simulations. Results show that the low frequency reflected shock-wave motion is mainly driven by the low frequency breathing of the separation bubble that comes from a modulation of the successive enlargements and shrinkages of the separated zone (medium frequency flapping of the shear-layer); the oscillations of the reflected shocks foot being in phase with the motion of the separation point.

Thermoacoustic properties of can-annular combustors are commonly investigated by means of single-can test-rigs. To obtain representative results, it is crucial to mimic can–can coupling present in the full engine. However, current approaches either lack a solid theoretical foundation or are not practicable for high-pressure rigs. In this study, we employ Bloch-wave theory to derive reflection coefficients that correctly represent can–can coupling. We propose a strategy to impose such reflection coefficients at the acoustic terminations of a single-can test-rig by installing passive acoustic elements, namely straight ducts or Helmholtz resonators. In an iterative process, these elements are adapted to match the reflection coefficients for the dominant frequencies of the full engine. The strategy is demonstrated with a network model of a generic can-annular combustor and a three-dimensional (3D) model of a realistic can-annular combustor configuration. For the latter, we show that can–can coupling via the compressor exit plenum is negligible for frequencies sufficiently far away from plenum eigenfrequencies. Without utilizing previous knowledge of relevant frequencies or flame dynamics, the test-rig models are adapted within a few iterations and match the full engine with good accuracy. Using Helmholtz resonators for test-rig adaption turns out to be more viable than using straight ducts.

In this paper, we present the steps taken to design and implement an intelligent cloud-based manager whose goal is to charge a fleet of electric school buses optimally to reduce power peaks on the grid. Emphasis is put on the design of the different subsystems rather than the performance of the charge manager since, at the time of writing, the system is awaiting deployment.

The COVID-19 pandemic negatively impacted the 2019/20 WHO European Region influenza surveillance. Compared with previous 4-year averages, antigenic and genetic characterisations decreased by 17% (3,140 vs 2,601) and 24% (4,474 vs 3,403). Of subtyped influenza A viruses, 56% (26,477/47,357) were A(H1)pdm09, 44% (20,880/47,357) A(H3). Of characterised B viruses, 98% (4,585/4,679) were B/Victoria. Considerable numbers of viruses antigenically differed from northern hemisphere vaccine components. In 2020/21, maintaining influenza virological surveillance, while supporting SARS-CoV-2 surveillance is crucial.

The intrinsic thermoacoustic (ITA) feedbackloop constitutes a coupling between flow, flame and acoustics that does not involve the natural acoustic modes of the system. One recent study showed that ITA modes in annular combustors come in significant number and with the peculiar behavior of clusters, i.e. several modes with close frequencies. In the present work an analytical model of a typical annular combustor is derived via Riemann invariants and Bloch theory. The resulting formulation describes the full annular system as a longitudinal combustor with an outlet reflection coefficient that depends on frequency and the azimuthal mode order. The model explains the underlying mechanism of the clustering phenomena and the structure of the clusters associated with ITA modes of different azimuthal orders. In addition, a phasor analysis is proposed, which enclose the conditions for which the 1D model remains valid when describing the thermoacoustic behavior of an annular combustor.

International audience; High Reynolds number supersonic flows require accurate predictions, in the one hand, for the design of industrial devices, and on the other hand, for the physical understanding and modeling of these high speed flows that still raise numerous scientific issues. To this end, Direct Numerical Simulations (DNS) are nowadays an adequate tool since all characteristic time and space scales are computed without using any modeling. Among the great variety of high-order numerical schemes using shock-capture features developed for DNS, high-order One-Step (OS) Monotonicity-Preserving (MP) schemes have been developed [1,2] that control the total truncation error involving both errors due to time integration and spatial discretization. The objective of this paper is to check the ability of the high-order OSMP scheme to accurately compute turbulent compressible flows with a special focus on the effect of the MP constraints on solutions of turbulent flows without shock wave. The classical3-D Taylor-Green vortex test case [3] is first used for evaluating the accuracy of the solver to compute continuous turbulent solutions. Secondly, the spatial development of a supersonic turbulent boundary layer is simulated. A compressible version of the Synthetic Eddy Method is developed for prescribing inflow conditions. We showed that these specific conditions greatly lower the adaptation length compared to more classical inflow conditions. As diffusion in the near wall region is one of the key phenomena, the influence of the viscous flux discretization is reviewed with 2nd-order and 4th-order centered approximations. Compared to reference solutions from the literature, we showed that the OSMP scheme produces reliable solutions that are in very good agreements with references. Even for bounded flows, the use of an order of accuracy higher than the 2nd-order for approximating the diffusive fluxes was shown to have a negligible influence on solutions. We conclude that the OSMP scheme coupled with a centered 2nd-order approximation for the diffusive fluxes constitutes a reliable numerical tool for the DNS of compressible turbulent flows, that is completely competitive compared to other approaches since the overall errors are lowered of about one order of magnitude for the same grid resolution.

Transport of neo-synthesized influenza A virus (IAV) viral ribonucleoproteins (vRNPs) from the nucleus to the plasma membrane involves Rab 11 but the precise mechanism remains poorly understood. We used metal-tagging and immunolabeling to visualize viral proteins and cellular endomembrane markers by electron microscopy of IAV-infected cells. Unexpectedly, we provide evidence that the vRNP components and the Rab11 protein are present at the membrane of a modified, tubulated endoplasmic reticulum (ER) that extends all throughout the cell, and on irregularly coated vesicles (ICVs). Some ICVs are found very close to the ER and to the plasma membrane. ICV formation is observed only in infected cells and requires an active Rab11 GTPase. Against the currently accepted model in which vRNPs are carried onto Rab11-positive recycling endosomes across the cytoplasm, our findings reveal that the endomembrane organelle that is primarily involved in the transport of vRNPs is the ER., Transport of neo-synthesized influenza A virus viral ribonucleoproteins (vRNPs) from the nucleus to the plasma membrane involves Rab 11 but the mechanism is unclear. Here the authors show that vRNPs are transported through a modified Rab11-positive endoplasmic reticulum and Rab11-dependent vesicles.

National audience; Les drones sont de plus en plus présents dans notre quotidien, passant du gadget technologique à l'outil de travail. Ils font désormais partie intégrante de la famille des objets connectés et constituent donc une nouvelle surface d'attaque.