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

Quelle rhétorique pour les articles scientifiques ?

Cet article présente une grille d’analyse rhétorique qui devrait pouvoir s’appliquer aux articles de recherche en informatique et aussi, nous l’espérons, dans d’autres domaines scientifiques. Nous exposons d’abord les trois concepts essentiels de l’analyse textuelle, théorie sur laquelle se fonde notre analyse rhétorique, c.-à-d. les présupposés, le paragraphe conceptuel et le tableau de la démarche rhétorique. Ensuite nous affinons les définitions de cinq fonctions rhétoriques générales issues de ce tableau et en ajoutons une nouvelle. Dans la dernière partie, nous dégageons les deux principales difficultés de cette approche : difficulté d’identifier les fonctions rhétoriques générales et difficulté de trouver des paragraphes conceptuels qui soient gouvernés par une seule de ces fonctions. Ces difficultés nous conduisent à définir de façon plus générale le paragraphe conceptuel et à le situer de façon plus précise dans le tableau de la démarche rhétorique et le plan IMRED.In this article I present a tentative rhetorical grid to be applied to research articles in computer science and hopefully, in other scientific fields. First, I outline the three main tenets of textual analysis, namely presupposition, the conceptual paragraph and the rhetorical process chart. I then refine five general rhetorical functions from this chart and add a further one. In the last section, I point out the main drawbacks of this approach, i.e., the difficulties faced in identifying general rhetorical functions and in finding conceptual paragraphs that exemplify only one of these functions. These difficulties lead me to a more general definition of the conceptual paragraph and a more accurate positioning of this unit of discourse within the rhetorical process chart and the IMRAD plan

Formation of helium lines in solar prominences

We summarize the results on the formation of the helium spectrum in solar prominences obtained over recent years. The radiative transfer problem under non-LTE conditions is solved to compute the profiles of the lines of He I and He II. The structure of the prominence-to-corona transition region (PCTR) has a major influence on the resulting spectrum of the resonance lines since they are formed mostly in this part of the prominence. However, subordinate lines are also affected by the structure of the PCTR. We pay particular attention to the formation of the He II 304 Å resonance line which is routinely observed from space, but yet not fully understood. Future steps in the modelling will be addressed

European communication networks in the Early Modern Age

Recent contributions to knowledge about early journalism developed in different parts of Europe*Italy, France, England, Germany, the Netherlands, Portugal, Spain . . . *have made it possible to trace a fairly precise map for the historical origin of this phenomenon. However, the scope of work carried out with a view to developing frameworks of interpretation to explain the reasons for this appearance is not as far-reaching. This paper reviews the recurring theoretical models found to date in the specific bibliography and proposes a new framework of interpretation, capable of encompassing the complexity and pan-European nature of early journalism in history

High Burden of Non-Influenza Viruses in Influenza-Like Illness in the Early Weeks of H1N1v Epidemic in France

BACKGROUND: Influenza-like illness (ILI) may be caused by a variety of pathogens. Clinical observations are of little help to recognise myxovirus infection and implement appropriate prevention measures. The limited use of molecular tools underestimates the role of other common pathogens. OBJECTIVES: During the early weeks of the 2009-2010 flu pandemic, a clinical and virological survey was conducted in adult and paediatric patients with ILI referred to two French University hospitals in Paris and Tours. Aims were to investigate the different pathogens involved in ILI and describe the associated symptoms. METHODS: H1N1v pandemic influenza diagnosis was performed with real time RT-PCR assay. Other viral aetiologies were investigated by the molecular multiplex assay RespiFinder19®. Clinical data were collected prospectively by physicians using a standard questionnaire. RESULTS: From week 35 to 44, endonasal swabs were collected in 413 patients. Overall, 68 samples (16.5%) were positive for H1N1v. In 13 of them, other respiratory pathogens were also detected. Among H1N1v negative samples, 213 (61.9%) were positive for various respiratory agents, 190 in single infections and 23 in mixed infections. The most prevalent viruses in H1N1v negative single infections were rhinovirus (62.6%), followed by parainfluenza viruses (24.2%) and adenovirus (5.3%). 70.6% of H1N1v cases were identified in patients under 40 years and none after 65 years. There was no difference between clinical symptoms observed in patients infected with H1N1v or with other pathogens. CONCLUSION: Our results highlight the high frequency of non-influenza viruses involved in ILI during the pre-epidemic period of a flu alert and the lack of specific clinical signs associated with influenza infections. Rapid diagnostic screening of a large panel of respiratory pathogens may be critical to define and survey the epidemic situation and to provide critical information for patient management

L'Instrument périodique

Cet ouvrage rassemble deux études sur le périodique littéraire du XVIIIe siècle : « Fonctions culturelles du périodique littéraire » de Claude Labrosse et « Forme et discours d’un journal révolutionnaire : les Révolutions de Paris en 1789 » de Pierre Rétat

Critères de sélection d’un corpus : exemple de l’anglais de l’informatique

Criteria for compiling a corpus. The example of English for computer science The aim of this article is to review the criteria to be taken into account when compiling a corpus, taking as an example the creation of a corpus of research articles in computer science written in English. Firstly we deal with how to choose the type of publication, then with the size, period, and necessary comprehension of the items that make up the corpus. Finally we consider the native speaker status of the authors, their nationality, and the instructions they receive, to finish with a closer look at the text itself and the parts which should be selected.Labrosse Pierre. Critères de sélection d’un corpus : exemple de l’anglais de l’informatique. In: Cahiers de l'APLIUT, volume 15, numéro 1, 1995. pp. 31-45