Les échelles de l'habiter

National audienceLa recherche " Les échelles de l'habiter " visait à explorer quelques traits des relations que les Hommes entretiennent avec l'espace, considérant que le couple domicile/travail ne peut pas ou plus constituer à lui seul un cadre satisfaisant ni même une approximation acceptable de ces relations. Du côté du domicile, la multiplicité des résidences se généralise, d'une manière ou d'une autre (multi résidence stricto sensu, résidences secondaires, tourisme). Du côté du travail, on observe aussi une tendance à la multilocalisation associée à un affaiblissement de la limite entre travail et non travail, tandis qu'un nombre croissant de personnes ne peut être considéré comme " travailleurs ". Surtout, l'extérieur du couple domicile/travail se développe considérablement en durée, en mobilité, en importance dans la vie des individus : commerce, loisirs, culture, rencontres, et

Photocurrent measurements in a Quantum Cascade Detector under strong magnetic field

International audienceIn the present work, we performed photocurrent measurement on a quantum cascade detector structure under strong magnetic field applied parallel to the growth axis. The photocurrent shows strong oscillations as a function of B. We develop a model in order to describe current as a function of magnetic field. The excellent agreement with the experimental data supports the idea that an elastic scattering process plays a central role in the behavior of those structures. Thanks to zero magnetic field consideration, we establish that dominant process is impurities scattering process. These experiments lead to the key parameters to understand and optimize those structure further

Dark current analysis of Quantum Cascade Detectors by Magneto-Resistance measurements

International audienceMagneto-transport experiments have been performed on Quantum Cascade Detectors. These experiments lead to the identification of the different electronic transitions from subbands in one cascade period to subbands in the following one. These transitions contribute to the total current flowing through the structure in the absence of illumination. This dark current is well described within a simple model based on the sum of diffusion events from one cascade to the next one through optical phonon mediated transitions. For the first time, the optical and electronic properties of such a complex heterostructure can be fully predicted without any other adjustable parameter than the doping density. This opens the way to a full quantum design of an infrared detector, in contrast with the phenomenological optimization of structures usually performed in this field

Barrier breakdown in a multiple quantum well structure

We explore a regime of unipolar electronic transport in a multiple quantum well structure with very large current discontinuities - up to five orders of magnitude. Magneto-transport experiments reveal different transport regimes. Quantum well impact ionization shifts the structure from a resistive down state, where the current flows through inter-well quantum tunneling, to a highly conductive up state. In the latter regime, the current leaks through a barrier suddenly broken down because of an efficient ionization of the first quantum well.Comment: 16 pages, 5 figure

Photocurrent analysis of quantum cascade detectors by magnetotransport

to be published in Phys. Rev. BInternational audiencePhotocurrent measurements have been performed on a quantum cascade detector structure under strong magnetic field B applied parallel to the growth axis. The photocurrent shows oscillations as a function of B. In order to describe this 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 these structures. We present a calculation of the 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 identify key parameters to optimize them further

Magnetotransport in quantum cascade detectors: analyzing the current under illumination

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

More rapid blood interferon α2 decline in fatal versus surviving COVID-19 patients

BackgroundThe clinical outcome of COVID-19 pneumonia is highly variable. Few biological predictive factors have been identified. Genetic and immunological studies suggest that type 1 interferons (IFN) are essential to control SARS-CoV-2 infection.ObjectiveTo study the link between change in blood IFN-α2 level and plasma SARS-Cov2 viral load over time and subsequent death in patients with severe and critical COVID-19.MethodsOne hundred and forty patients from the CORIMUNO-19 cohort hospitalized with severe or critical COVID-19 pneumonia, all requiring oxygen or ventilation, were prospectively studied. Blood IFN-α2 was evaluated using the Single Molecule Array technology. Anti-IFN-α2 auto-Abs were determined with a reporter luciferase activity. Plasma SARS-Cov2 viral load was measured using droplet digital PCR targeting the Nucleocapsid gene of the SARS-CoV-2 positive-strand RNA genome.ResultsAlthough the percentage of plasmacytoid dendritic cells was low, the blood IFN-α2 level was higher in patients than in healthy controls and was correlated to SARS-CoV-2 plasma viral load at entry. Neutralizing anti-IFN-α2 auto-antibodies were detected in 5% of patients, associated with a lower baseline level of blood IFN-α2. A longitudinal analysis found that a more rapid decline of blood IFN-α2 was observed in fatal versus surviving patients: mortality HR=3.15 (95% CI 1.14–8.66) in rapid versus slow decliners. Likewise, a high level of plasma SARS-CoV-2 RNA was associated with death risk in patients with severe COVID-19.ConclusionThese findings could suggest an interest in evaluating type 1 IFN treatment in patients with severe COVID-19 and type 1 IFN decline, eventually combined with anti-inflammatory drugs.Clinical trial registrationhttps://clinicaltrials.gov, identifiers NCT04324073, NCT04331808, NCT04341584

Toulouse, territoire Garonne. Nouveaux modes d’habiter

Les systèmes géographiques que sont les parcs, les bois, les zones agricoles de bord de ville, les lignes de force collinaires, les réseaux hydrographiques, représentent les supports actifs d'une nouvelle urbanité. Parviennent-ils à allier la conscience de la grande échelle à celle de l'ancrage dans un territoire et l'urbain à un nouveau rapport à la nature ? Cet ouvrage explore la métropole toulousaine autour du fleuve Garonne, de la confluence Ariège jusqu'à la confluence de l'Hers et de la Save à Grenade-sur-Garonne. Trente-six kilomètres de fleuve pour comprendre les nouvelles questions qui se posent à nous sur la grande échelle de la ville contemporaine en partant de l'hypothèse que la majeure partie de ce territoire défini comme inconstructible par le Plan de Prévention des Risques d'Inondation (PRI), peut être un lieu porteur de nouvelles manières d'habiter et que sur les rives du fleuve se dessinent les territoires majeurs de la ville de demain. La Garonne permettrait donc de penser une architecture du territoire à grande échelle

Les fragilités urbaines d’une métropole attractive

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