Spectral Diagnostics of Active Prominences

Active prominences exhibit plasma motions, resulting in difficulties with the interpretation of spectroscopic observations. These solar features being strongly influenced by the radiation coming from the solar disk, Doppler dimming or brightening effects may arise, depending on which lines are observed and on the velocity of the plasma. Interlocking between the different atomic energy levels and non local thermodynamic equilibrium lead to non-trivial spectral line profiles, and this calls for complex numerical modelling of the radiative transfer in order to understand the observations. We present such a tool, which solves the radiative transfer and statistical equilibrium for H, He I, He II, and Ca II, in moving prominences where radial plasma motions are taking place. It is found that for isothermal, isobaric prominence models, the He II resonance lines are very sensitive to the Doppler effect and show a strong Doppler dimming. The Ca II lines are not very sensitive to the Doppler effect for the prominence models considered here. We illustrate how the code makes it possible to retrieve the plasma thermodynamic parameters by comparing computed and observed line profiles of hydrogen and helium resonance lines in a quiescent prominence.Comment: 6 pages, 5 figures. In press,"Physics of Chromospheric Plasmas" (Coimbra), ASP 368, 337 (2007). Revised version matches published version

The Helium spectrum in erupting solar prominences

Even quiescent solar prominences may become active and sometimes erupt. These events are occasionally linked to coronal mass ejections. However we know very little about the plasma properties during the activation and eruption processes. We present new computations of the helium line profiles emitted by an eruptive prominence. The prominence is modelled as a plane-parallel slab standing vertically above the solar surface and moving upward as a solid body. The helium spectrum is computed with a non local thermodynamic equilibrium radiative transfer code. The effect of Doppler dimming / brightening is investigated in the resonance lines of He I and He II formed in the EUV, as well as on the He I 10830 A and 5876 A lines. We focus on the line profile properties and the resulting integrated intensities. It is shown that the helium lines are very sensitive to Doppler dimming effects. We also study the effect of frequency redistribution in the formation mechanisms of the resonance lines and find that it is necessary to use partial redistribution in frequency for the resonance lines.Comment: 5 pages, 4 figures. Proceedings of IAU GA 2006, JD03: Solar Active Regions and 3D Magnetic Structure. See also a more detailed paper at astro-ph/060822

A Time-Evolving 3D Method Dedicated to the Reconstruction of Solar plumes and Results Using Extreme Ultra-Violet Data

An important issue in the tomographic reconstruction of the solar poles is the relatively rapid evolution of the polar plumes. We demonstrate that it is possible to take into account this temporal evolution in the reconstruction. The difficulty of this problem comes from the fact that we want a 4D reconstruction (three spatial dimensions plus time) while we only have 3D data (2D images plus time). To overcome this difficulty, we introduce a model that describes polar plumes as stationary objects whose intensity varies homogeneously with time. This assumption can be physically justified if one accepts the stability of the magnetic structure. This model leads to a bilinear inverse problem. We describe how to extend linear inversion methods to these kinds of problems. Studies of simulations show the reliability of our method. Results for SOHO/EIT data show that we are able to estimate the temporal evolution of polar plumes in order to improve the reconstruction of the solar poles from only one point of view. We expect further improvements from STEREO/EUVI data when the two probes will be separated by about 60 degrees

Les défaillances de l'accompagnement des demandeurs d'asile et leurs conséquences sur la santé mentale

̀A partir de nos activités au Réseau Samdarra, nous documentons ici la réalité de la prise en charge du public demandeur d'asile, notamment au niveau de l'hébergement et interrogeons le sens de cet accompagnement aujourd'hui et les conséquences sur la santé mentale. Des normes minimales d'accueil " conditions matérielles d'accueil " pour les demandeurs d'asile ont été prévues par les textes européens et introduites dans le droit français afin de " garantir un niveau de vie adéquat pour la santé et d'assurer la subsistance des demandeurs"

RNA Relics and Origin of Life

A number of small RNA sequences, located in different non-coding sequences and highly preserved across the tree of life, have been suggested to be molecular fossils, of ancient (and possibly primordial) origin. On the other hand, recent years have revealed the existence of ubiquitous roles for small RNA sequences in modern organisms, in functions ranging from cell regulation to antiviral activity. We propose that a single thread can be followed from the beginning of life in RNA structures selected only for stability reasons through the RNA relics and up to the current coevolution of RNA sequences; such an understanding would shed light both on the history and on the present development of the RNA machinery and interactions. After presenting the evidence (by comparing their sequences) that points toward a common thread, we discuss a scenario of genome coevolution (with emphasis on viral infectious processes) and finally propose a plan for the reevaluation of the stereochemical theory of the genetic code; we claim that it may still be relevant, and not only for understanding the origin of life, but also for a comprehensive picture of regulation in present-day cells

État des lieux national de la santé mentale des demandeurs d'asile et réfugiés au sein du dispositif national d'accueil. Mise en perspective problématique

National audienceNous proposons ici d'interroger la problématique du recueil du récit et de son objectivation en se nourrissant de certains écarts dans la manière d'appréhender ce récit

Non-contrast-enhanced MR angiography using time-spin labelling inversion pulse technique for detecting crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with surgical findings.

OBJECTIVES: Investigate the feasibility and evaluate the accuracy of non-contrast-enhanced MR angiography (NC-MRA) using time-spin labelling inversion pulse (time-SLIP)to identify crossing renal vessels (CRVs) in children requiring surgical treatment of ureteropelvic junction (UPJ) obstructionand compare to laparoscopic findings. MATERIALS AND METHODS: Nineteen children ranging from 6 to 16 years of age underwent NC-MRA using the time-SLIP technique before surgery. Two independent readers analysed the MRA images. Number of renal arteries and presence or absence of CRVs were identified and compared with surgicalfindings. Image quality was assessed, as well as the presence of CRVs and measurement of renal pelvis diameter. Intra and inter-reader agreement was calculated using Cohen's kappa coefficient and Bland-Altman plots. RESULTS: The overall image quality was fair or good in 88% of cases. NC-MRA demonstrated CRVs at the level of the obstruction in 10 children and no CRV in 9 children. All were confirmed intra-operatively except in one of the nine children. Sensitivity, specificity, NPV, PPV for predicting CRVs were 92%, 100%, 100% and 87.5%, respectively, for both readers. CONCLUSION: NC-MRA is a good alternative to contrast-enhanced MRA and CT scanning for identifying CRVs in children with symptomatic UPJ. KEY POINTS: • Time-SLIP technique offers acceptable imaging quality for identifying crossing renal vessel. • Time-SLIP technique is easy to apply to the renal MRA examination. • Time-SLIP technique is an alternative to contrast-enhanced MRA and CT scanning

Vieille-Toulouse (Haute-Garonne) : des vestiges de préparations culinaires ?

International audienc

Apports de la microscopie biphotonique intravitale pulmonaire à l'étude de la physiopathologie de la maladie du charbon

Bacillus anthracis, l'agent infectieux responsable de la maladie du charbon, est un agent pathogène majeur du risque biologique provoqué, notamment en raison de la sévérité de la forme respiratoire de la maladie. Celle-ci résulte de l'inhalation de spores dont les mécanismes de pénétration au niveau pulmonaire sont mal connus à l'heure actuelle. Cette thèse présente les apports des microscopies confocale et biphotonique à l'étude de ces mécanismes de pénétration des spores inhalées. Le modèle murin CX3CR1+/gfp, dont la sous-population CD11b+ de cellules dendritiques (DCs) exprime constitutivement la protéine de fluorescence verte (GFP), a été utilisé dans ces travaux. Une première partie présente le développement d'une méthode automatisée de discrimination des DCs parmi d'autres populations cellulaires exprimant le même fluorophore, en se basant sur le calcul d'un coefficient morphologique. Cette méthode a permis d'étudier dans un deuxième temps le comportement spécifique de la sous-population de DCs CD11b, après infection par des spores de B. anthracis. L'étude microscopique a été d'abord effectuée in situ, c'est-à-dire sur des explants pulmonaires maintenus dans des conditions favorables à la préservation de l'activité cellulaire, puis in vivo, sur des souris anesthésiées et ventilées. Le protocole d'imagerie tire profit d'une stratégie d'acquisition et de traitement a posteriori des données permettant de surmonter, sans contrainte mécanique appliquée à l'organe, les problèmes de focalisation liés aux mouvements thoraciques durant la ventilation de l'animal. Cette stratégie originale utilise un sur-échantillonnage de l'acquisition et profite du signal de seconde harmonique généré par le collagène comme référence spatiale ; elle a permis l'observation in vivo d'interactions entre DCs et macrophages au niveau pulmonaire. Ces interactions, de type synapse immunologique, sont favorisées par l'infection et présentent donc un rôle fonctionnel qui reste à définir. La formation de synapses immunologiques entre macrophages et DCs pourrait non seulement représenter un chaînon manquant à l'explication de la pénétration des spores de B. anthracis au niveau pulmonaire, mais pourrait aussi constituer un enjeu crucial dans la compréhension de la réponse immunitaire associée aux infections pulmonaires.Bacillus anthracis, the causative agent of anthrax, is a major bioterrorism pathogen mainly because it can lead to a severe respiratory form of the disease. This form results from inhalation of spores, whose ways of entry into the lungs are not fully understood. This thesis reports the contribution of confocal and two-photon microscopy to the study of the penetration mechanisms of inhaled spores. The animal model utilized was CX3CR1+/gfp mouse, which constitutively expresses the green fluorescent protein (GFP) on CD11b+ dendritic cells (DCs). First, we present an automated method allowing discrimination of DCs among other GFP expressing cells, based on a morphologic coefficient. This method was then applied to the study of the specific behavior of CD11b DCs, after infection by B. anthracis spores. The microscopic study was first performed in situ, i.e. on explanted organs kept in conditions favorable to cell dynamics, then in vivo, i.e. on anesthetized and ventilated mice. In this case the imaging protocol profits from both acquisition and post-processing strategies, and allowed overcoming the focalization pitfalls coming from chest movements during ventilation. This novel strategy is based on an over-sampling of frame acquisition and utilizes second harmonic generation signal from alveolar collagen as a spatial reference. It led to the first ever in vivo observation of interactions between DCs and macrophages at the lung level. These immunological synapse-like structures are promoted by infection and thus display a functional role unknown until now. The formation of macrophages-DCs immunological synapses not only could represent a missing-link in figuring out the B. anthracis spore penetration mechanisms at the lung level, but more importantly could lead to a better understanding of the immune response associated with pulmonary infections.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF