Étude de la propagation des ondes radio dans les environnements planétaires

In the Solar System, the study of the radio emissions at very low frequencies (from few kHz up to few MHz) is a source of information about the processes of acceleration of electrons in the planetary environment and in the Solar Wind. The understanding of the emission mechanisms and the knowledge of the methods of detection enable to probe the physical conditions of the plasma sources. This dissertation deals with the propagation of the radio waves in the planetary environment. Their inhomogeneous characteristics could induce a non-linear path of rays in addition to the anisotropy of the plasma caused by the presence of magnetic fields. The study of wave propagation effects permits to relax the hypothesis of rectilinear propagation between the source and the detectors, to track the evolution of the wave characteristics and to probe the propagating medium. The theoretical study of the propagation of electromagnetic waves in magnetized and anisotropic plasma led to the development of a generalized ray tracing code, that includes the calculation of the polarization state of the wave along the rays: ARTEMIS-P (Anisotropic Ray Tracer for Electromagnetism in Magnetosphere, Ionosphere and Solar wind, including Polarization). This code led to two studies: on the one hand, the modeling of the "Over-the-Horizon" effect consisting of the detection of guided radio signatures associated with lightning bursts in Saturn atmosphere, and on the other hand, the characterization of the influence of the auroral cavities profile on the beaming of the Auroral Kilometric Radiation (AKR) at the Earth.Dans le système solaire, l’étude des rayonnements radio très basse fréquence (de quelques kHz à quelques MHz) permet d’obtenir des informations sur les proces- sus d’accélération des électrons dans les environnements planétaires et dans le vent solaire. La compréhension des mécanismes d’émission et la maîtrise des moyens de détection permettent de sonder les conditions physiques dans les plasmas sources. Cette thèse porte sur l’étude de la propagation des ondes radio dans les environne- ments planétaires. Leur caractère inhomogène implique que la propagation n’est pas obligatoirement rectiligne, et la présence des champs magnétiques ambiants rend le plasma anisotrope. L’étude des phénomènes de propagation permet de s’affranchir d’une hypothèse de propagation en ligne droite entre les sources du rayonnement et les détecteurs, de suivre l’évolution des caractéristiques des ondes et de sonder le milieu de propagation. L’étude théorique de la propagation des ondes électroma- gnétiques dans les plasmas magnétisés a mené au développement d’un code général de tracé de rayons, calculant également l’état de polarisation de l’onde le long des rayons : ARTEMIS-P (Anisotropic Ray Tracer for Electromagnetism in Magnetosphere, Ionosphere and Solar wind, including Polarization). Ce code nous a permis de me- ner deux études : l’effet de détection au-delà de l’horizon des signatures radio des éclairs d’orages de Saturne et l’influence de l’ionosphère sur la propagation des ondes radio produites dans l’atmosphère de Saturne, et l’influence du profil des cavités auro- rales sur le diagramme de rayonnement des sources de l’émission kilométrique terrestre

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Analyser la durabilité du développement de valorisations non alimentaires d'agro-ressources.

This thesis is about our analysis of the activities of the French competitiveness cluster "Industrie et Agro-Ressources" (IAR) with regard to the different stakes of sustainable development. Established in 2005 in the Picardie and Champagne-Ardenne regions, this cluster supports innovative valorisation projects of agricultural resources by industry. Our approach is based on an analysis of the challenges that sustainable development aims to solve, with a particular focus on the case of the agriculture and agro-industries. We also use ideas and concepts from several types of sustainability analysis methodologies, including the construction and use of sustainable development indicators. This work resulted in the development of IDDAgro, a decision support system dedicated to the evaluation of the sustainability of projects supported by the IAR cluster. One backbone of this set of sustainable development indicators is the assessment of the potential impacts of agroindustrial projects life cycles. Our approach was validated by applying the IDDAgro tool to real life projects. Limited access to information necessary for sustainability assessments was the main obstacle in this research. It prevented the planned application of our approach to study the ethanol production of one of the IAR cluster's partners, for which a literature study had been carried out. All these results finally enabled us to develop and present concrete suggestions to the IAR cluster. They aim at improving the integration of sustainable development stakes in its activities.Cette thèse porte sur l'analyse des activités du pôle de compétitivité Industrie et Agro-Ressources (IAR) face aux enjeux du développement durable. Implanté depuis 2005 au sein des régions Picardie et Champagne-Ardenne, ce pôle soutient des projets innovants de valorisation d'agro-ressources par l'industrie. Notre démarche repose sur une analyse des défis auxquels le développement durable cherche à répondre, mettant en perspective la position de l'agriculture et des agro-industries. Nous nous appuyons également sur les apports de plusieurs approches méthodologiques d'analyse de la durabilité, en particulier la construction et l'usage des indicateurs de développement durable. Ces travaux ont abouti au développement d'IDDAgro, méthodologie d'aide à la décision dédiée à l'évaluation des projets soutenus par le pôle IAR au regard des enjeux du développement durable. Cette grille d'indicateurs de développement durable repose sur l'évaluation des impacts potentiels du cycle de vie des projets agro-industriels. Notre démarche a été validée par le test d'IDDAgro sur des cas réels. L'accès aux informations pour l'évaluation de la durabilité a constitué le principal obstacle à ces travaux, en particulier pour l'application de notre approche à l'étude de la production d'éthanol d'un site partenaire du pôle, pour laquelle une étude bibliographique a été réalisée. L'ensemble de ces résultats nous permet finalement de soumettre au pôle IAR des propositions visant à améliorer l'intégration des enjeux du développement durable dans ses activités

Etude de la propagation des ondes radio dans les environnements planétaires

Dans le système solaire, l'étude des rayonnements radio très basse fréquence (de quelques kHz à quelques MHz) permet d'obtenir des informations sur les processus d'accélération des électrons dans les environnements planétaires et dans le vent solaire. La compréhension des mécanismes d'émission et la maîtrise des moyens de détection permettent de sonder les conditions physiques dans les plasmas sources. Cette thèse porte sur l'étude de la propagation des ondes radio dans les environnements planétaires. Leur caractère inhomogène implique que la propagation n'est pas obligatoirement rectiligne, et la présence des champs magnétiques ambiants rend le plasma anisotrope. L'étude des phénomènes de propagation permet de s'affranchir d'une hypothèse de propagation des ondes électromagnétiques dans les plasmas anisotropes et magnétisés a mené au développement d'un code général de tracé de rayons, calculant également l'état de polarisation de l'onde le long des rayons : ARTEMIS-P (Anisotropic Ray Tracer for Electromagnetism in Magnetosphere, Ionosphere and Solar wind, including Polarization). Ce code nous a permis de mener deux études : l'effet de détection au-delà de l'horizon des signatures radio des éclairs orages de Saturne et l'influence de la présence de l'ionosphère sur la propagation des ondes radio produites dans l'atmosphère de Saturne, et l'influence du profil des cavités aurorales sur le diagramme de rayonnement des sources de l'émission kilométrique terrestre.In the Solar System, the study of the radio emissions at very low frequencies (from few kHz up to few MHz) is a source of information about the processes of acceleration of electrons in the planetary environment and in the Solar Wind. The understanding of the emission mechanisms and the knowledge of the methods of detection enable to probe the physical conditions of the plasma sources. This dissertation deals with the propagation of the radio waves in the planetary environment. Their inhomogeneous characteristics could induce a non-linear path of rays in addition to the anisotropy of the plasma caused by the presence of magnetic fields. The study of wave propagation effects permits to relax the hypothesis of rectilinear propagation between the source and the detectors, to track the evolution of the wave characteristics and to probe the propagating medium. The theoretical study of the propagation of electromagnetic waves in magnetized and anisotropic plasma led to the development of a generalized ray tracing code, that includes the calculation of the polarization state of the wave along the rays : ARTEMIS-P (Anisotropic Ray Tracer for Electromagnetism in Magnetosphere, Ionosphere and Solar wind, including Polarization). This code led to two studies : on the one hand, the modeling of the "Over-the-Horizon" effect consisting of the detection of guided radio signatures associated with lightning bursts in Saturn atmosphere, and on the other hand, the characterization of the influence of the auroral cavities profile on the beaming of the Auroral Kilometric Radiation (AKR) at the Earth.PARIS-Observatoire (751142302) / SudocSudocFranceF

Gestion intégrée des sols et sites urbains dégradés

La reconquête des espaces dégradés en milieu urbain et leur retour à un usage économique ont acquis une importance particulière dans l'Union européenne ces quinze dernières années. Mais les espaces à usage agricole situés en périphérie des villes continuent d'être soumis au mitage (2), souvent du fait de la complexité de la reconversion des sites urbains dégradés. Afin de modifier ces pratiques, il est nécessaire d'intégrer les exigences du développement durable et les différentes situations socio-économiques, légales et politiques en réunissant les diverses disciplines et les porteurs d'enjeux

Propagation of Saturn's radio lightning studied by three-dimensional ray tracing

International audienc

Propagation of Saturn's radio lightning studied by three-dimensional ray tracing

International audienc

Propagation of Saturn's radio lightning studied by three-dimensional ray tracing

International audienc

Rapid and Accurate Identification of Human Isolates of Pasteurella and Related Species by Sequencing the sodA Gene

The identification of Pasteurella and related bacteria remains a challenge. Here, a 449- to 473-bp fragment (sodA(int)) internal to the sodA gene, encoding the manganese-dependent superoxide dismutase, was amplified and sequenced with a single pair of degenerate primers from the type strains of Pasteurella (18 strains), Gallibacterium (1 strain), and Mannheimia (5 strains) species. The sodA(int)-based phylogenetic tree was in general agreement with that inferred from the analysis of the corresponding 16S rRNA gene sequences, with members of the Pasteurella sensu stricto cluster (Pasteurella multocida, Pasteurella canis, Pasteurella dagmatis, and Pasteurella stomatis) forming a monophyletic group and Gallibacterium and Mannheimia being independent monophyletic genera. However, the sodA(int) sequences showed a markedly higher divergence than the corresponding 16S rRNA genes, confirming that sodA is a potent target to differentiate related species. Thirty-three independent human clinical isolates phenotypically assigned to 13 Pasteurella species by a reference laboratory were successfully identified by comparing their sodA(int) sequences to those of the type species. In the course of this work, we identified the first Gallibacterium anatis isolate ever reported from a human clinical specimen. The sodA(int) sequences of the clinical isolates displayed less than 2.5% divergence from those of the corresponding type strains, except for the Pasteurella pneumotropica isolates, which were closely related to each other (>98% sodA(int) sequence identity) but shared only 92% sodA(int) identity with the type strain. The method described here provides a rapid and accurate tool for species identification of Pasteurella isolates when access to a sequencing facility is available

Natural variation in infection specificity of Caenorhabditis briggsae isolates by two RNA viruses.

Antagonistic relationships such as host-virus interactions potentially lead to rapid evolution and specificity in interactions. The Orsay virus is so far the only horizontal virus naturally infecting the nematode C. elegans. In contrast, several related RNA viruses infect its congener C. briggsae, including Santeuil (SANTV) and Le Blanc (LEBV) viruses. Here we focus on the host's intraspecific variation in sensitivity to these two intestinal viruses. Many temperate-origin C. briggsae strains, including JU1264 and JU1498, are sensitive to both, while many tropical strains, such as AF16, are resistant to both. Interestingly, some C. briggsae strains exhibit a specific resistance, such as the HK104 strain, specifically resistant to LEBV. The viral sensitivity pattern matches the strains' geographic and genomic relationships. The heavily infected strains mount a seemingly normal small RNA response that is insufficient to suppress viral infection, while the resistant strains show no small RNA response, suggesting an early block in viral entry or replication. We use a genetic approach from the host side to map genomic regions participating in viral resistance polymorphisms. Using Advanced Intercrossed Recombinant Inbred Lines (RILs) between virus-resistant AF16 and SANTV-sensitive HK104, we detect Quantitative Trait Loci (QTLs) on chromosomes IV and III. Building RILs between virus-sensitive JU1498 and LEBV-resistant HK104 followed by bulk segregant analysis, we identify a chromosome II QTL. In both cases, further introgressions of the regions confirmed the QTLs. This diversity provides an avenue for studying virus entry, replication, and exit mechanisms, as well as host-virus specificity and the host response to a specific virus infection