200 research outputs found
Etude de la réception d'une oeuvre littéraire (Jean Forton, écrivain oublié ?)
No full textPourquoi Jean Forton (1930-1982), romancier français publié par Gallimard de 1954 à 1966, salué par la critique de l époque et candidat au Goncourt à plusieurs reprises, est-il tombé dans un oubli quasi-complet ? Pour répondre à cette question, nous avons étudié l évolution de la réception de son œuvre de 1951 à nos jours, à travers la presse régionale et nationale, afin de clarifier le rôle des événements, des critiques et du contexte littéraire. Au travers de la destinée éditoriale de Forton, nous avons cherché à savoir si le fait de vivre en province pouvait avoir des incidences sur la notoriété d un auteur. Enfin, nous avons formulé des hypothèses sur la réception future de l'œuvre de Jean Forton, en prenant en compte les bouleversements récents et actuels du monde de l édition, la place de plus en plus restreinte de la littérature française dans le monde, ainsi que les changements d attitude dans la lecture.Why has Jean Forton a French novelist published by Gallimard from 1954 to 1966, hailed by the critics of the time and a one-time Goncourt Prize runner fallen into near-oblivion ? To answer this question, we have examined the evolution of the way his works have been received from 1951 to this day, through both the national and regional press, with a view to clarifying the influence of events, critiques and literary context. By examining Forton s varied editorial fortunes, we try to determine whether the fact of living in the provinces has an effect on the fame of an author. The last part of our dissertation deals with a number of hypotheses concerning the future reception of Jean Forton s works. We take into account the recent and current upheavals within the world of publishing, the increasingly confined status accorded to French literature worldwide, as well as the changes in readers attitudes to literature.LE MANS-BU Lettres (721812108) / SudocSudocFranceF
Microstructure and magnetic properties of pure iron for cyclotron electromagnets
No full textThe microstructural and magnetic properties of pure iron ingots used as cores of cyclotron electromagnets have been investigated upon annealing sequence from 650 degrees C to 820 degrees C. Optical Microscopy, Scanning Electron Microscopy, and X-ray Diffraction were employed in the structural analysis, while magnetization curve and hysteresis loops were obtained in rod and ring samples, machined out of the large (around 4 m diameter) cast yoke, by combination of point-by-point and continuous (frequency f = 0.03 Hz) hysteresisgraph methods. Quite inhomogeneous grain structure was observed, with large and irregularly shaped grains (size of several mm), posing special constraints to the conventional magnetic testing approach (e.g., the IEC 60404-4 standard). Reproducible DC magnetic measurements could be performed using large cross-sectional area samples and suitable spatial averaging of the measured effective magnetic field, the eddy current effects being minimized at the same time. Full magnetic softening was obtained upon the annealing sequence in the absence of grain growth and change of distribution and morphology of the inclusions. The measured increase of permeability and decrease of coercivity are therefore entirely ascribed to the relief of the residual stresses, affecting the as-prepared and preliminarily annealed massive (similar to 80 x 10(3) kg) yoke. By recognizing in this way the role of stresses, we are eventually able to estimate the additional contributions to the material coercivity provided by the grain boundaries and the precipitated impurities, the latter playing a major role
Estrelas gigantes ricas em lítio: um estudo da anomalia química e do campo magnético desses objetos
No full textAccording to the standard theory of stellar evolution, low-mass stars (spectral type K and G) must reach the beginning of the main sequence (ZAMS) with
lithium (Li) abundance near to the meteoritical value, which is ∼ 3.3 dex, and hold
this abundance approximately constant until they reach the first dredge-up zone in
the Red Giant Branch (RGB). After completion of the dilution processes, already
in the red clump, such stars should present a relatively low Li abundance (< 1.5
dex). However, approximately 1-2% of all observed K and G giant stars have an
abnormally high Li abundance (≥ 1.5 dex). It is possible to find in the literature
many attempts to reconcile theory and observation, but none of them is capable of
explaining all the scenarios in which those chemical anomalies occur.
Our work aims at presenting a new study of lithium-rich G and K spectral
type stars and at analyzing the possible existence of particular characteristics to the
lithium-rich stars that present detected magnetic field. We have assembled a sample
of 20 giant stars — taken from Charbonnel e Balachandran (2000), Kumar, Reddy
e Lambert (2011), and Lèbre et al. (2009) — and we computed the atmospheric
parameters and Li abundances for those stars. We also computed the longitudinal
magnetic field for a sub-sample of stars with observed high-resolution spectra available at PolarBase (Petit et al., 2014). In order to get those results, we have used the
Least-Squares Deconvolution (LSD) technique (Donati et al., 1997) and the spectral analysis tool iSpec (Blanco-Cuaresma et al., 2014). Concerning the evolutionary
states, we have used parallaxes recently provided by ESA’s Gaia space observatory.
We obtained results for the atmospheric parameters and the Li abundance using
the same procedure for all stars. Thus, we have the reliability in comparing stars
that possibly had their spectra treated in different ways and that were observed by
different instruments. We obtained relations between Li abundance, rotation velocity, and presence of a magnetic field according to what is predicted in the literature.
We conclude that each star needs to be analyzed individually and with a more refined spectroscopy such that the real nature of its Li abundance is unraveled. The
12C/13C isotopic ratio, and the C/N elemental ratio, need to be investigated so that
we can determine precisely the position of some stars (of our sample) on the H-R
diagram. The influence of the magnetic field on the Li abundance is still not clear,
since we cannot rule out the existence of a non-superficial field acting inside the
convective zone and altering mixing mechanisms.Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPqDe acordo com a teoria padrão de evolução estelar, as estrelas pouco massivas (tipo espectral K e G) devem chegar ao início da sequência principal (ZAMS)
com uma abundância de lítio (Li) próxima ao valor meteorítico, que é de ∼ 3, 3 dex,
e manter essa abundância aproximadamente constante até que atinjam a primeira
zona de dragagem no Ramo das Gigantes Vermelhas (RGB). Após o término dos
processos de diluição, já na região do red clump, tais estrelas deveriam apresentar
uma abundância de lítio relativamente baixa (< 1, 5 dex). Entretanto, aproximadamente 1-2% de todas as estrelas gigantes K e G observadas apresentam uma
abundância anormalmente alta de lítio (≥ 1, 5 dex). Várias são as possibilidades encontradas na literatura para reconciliar teoria e observação, porém nenhuma delas
é capaz de explicar todos os cenários em que essas anomalias químicas acontecem.
O objetivo do nosso trabalho é apresentar um novo estudo sobre as estrelas
ricas em lítio de tipo espectral G e K e analisar se existem características particulares
às ricas em lítio que apresentam campo magnético detectado. Montamos uma base
de dados de 20 estrelas gigantes — retiradas de Charbonnel e Balachandran (2000),
Kumar, Reddy e Lambert (2011), e Lèbre et al. (2009) — e calculamos os parâmetros atmosféricos e as abundâncias de Li para essas estrelas. Também calculamos
o campo magnético longitudinal para uma subamostra das estrelas com espectros
observados em alta resolução e disponíveis no PolarBase (Petit et al., 2014). Para obtermos tais resultados, utilizamos a técnica do Least-Squares Deconvolution (LSD)
(Donati et al., 1997) e a ferramenta de análise espectral iSpec (Blanco-Cuaresma
et al., 2014). No que diz respeito aos estados evolutivos, utilizamos as paralaxes recentemente fornecidas pela missão espacial Gaia (ESA). Obtivemos resultados para
os parâmetros atmosféricos e abundância de Li usando o mesmo procedimento para
todas as estrelas. Assim, temos a confiabilidade em comparar estrelas que possivelmente tiveram seus espectros tratados de maneiras distintas e que foram observadas
por diferentes instrumentos. Obtivemos relações entre abundância de Li, velocidade
de rotação, e presença de campo magnético que estão de acordo com o previsto na
literatura. Concluímos que cada estrela precisa ser analisada de forma individual e
com uma espectroscopia mais refinada para que a real natureza de sua abundância de Li seja desvendada. A razão isotópica 12C/13C, e a razão elementar C/N,
precisam ser investigadas para determinarmos com precisão a posição das estrelas
(da nossa base) no diagrama H-R. A influência do campo magnético na abundância de Li ainda não é bastante clara, já que não podemos descartar a existência
de um campo não superficial atuando no interior da zona convectiva e alterando
mecanismos de mistura
Interferon Regulatory Factor 1 polymorphisms and susceptibility to Plasmodium falciparum malaria.
No full textTreatment of histologically mild hepatitis C virus infection with interferon and ribavirin: a multicentre randomized controlled trial
No full textCurrent guidelines advocate no treatment for patients with histologically mild hepatitis C virus (HCV) infection. This was a UK multicentre randomized controlled trial comparing alpha-interferon (3 MU thrice weekly) + ribavirin (1000-1200 mg/day) for 48 weeks with no treatment in treatment naive, adult patients with histologically mild chronic HCV infection. The aim was to compare benefits, safety and efficacy of combination therapy with alpha-interferon 2b and ribavirin for 48 weeks with no treatment (current standard management) in this patient group. In the treatment group 32 of 98 (33%) patients achieved a sustained virological response (SVR). Patients infected with genotype 1 had a lower SVR than those infected with genotype non-1 (18% vs 49% P = 0.02). No patients who failed to achieve a 2-log drop in viral load at 12 weeks achieved SVR. Improvements in quality of life 24 weeks postcessation of therapy compared with baseline using the SF-36 questionnaire measures were observed in the treated group. For patients with mild HCV infection with viral genotype non-1, the results are sufficiently good to suggest that therapeutic decisions should no longer be biopsy-driven. For patients infected with genotype 1, a liver biopsy is still indicated as the low chance of SVR is outweighed by an unacceptable burden of side-effects. Patients who fail to respond by 12 weeks of therapy should have their treatment curtailed early.</p
New insights into hepatitis C
No full textHepatitis C infection is characterised by three key features, which are the consequence of a complex interaction between genetic determinants of immune and other host factors and viral characteristics: 1. A high rate of viral persistence after acute infection resulting from a combination of weak T cell responsiveness and specific viral mechanisms of immune escape. 2. Marked interindividual variability in end-organ damage (fibrosis and cirrhosis), probably due to host genetic polymorphisms in genes governing the immune response and fibrosis pathways in addition to viral pathogenicity factors. 3. Significant resistance to antiviral therapies. Viral mechanisms of antiviral resistance parallel those of viral persistence, and include the intriguing possibility that hepatitis C may infect immunologically privileged sites such as the central nervous system.</p
Investigando a rotação, o magnetismo e as abundâncias químicas de estrelas do tipo solar através de modelos de evolução e espectroscopia: da pré-sequência principal à gigante vermelha
No full textThe study of the rotational evolution of the Sun and solar-type stars is undoubtedly one of the fields of stellar astrophysics in major evidence today. There are numerous
issues still far from being fully understood, which makes research in this field intense and
dynamic. Among these issues is the understanding of the phenomena that influence the
angular momentum of stars during their formation, still in the Pre-Main Sequence phase;
the understanding of the mechanisms that act in the stellar interiors throughout evolution,
which end up determining, for example, the rotation profile of a solid body observed on the
Sun; or which transport mechanisms act in evolved stars, which undergo profound changes
in their structure, and manifest peculiar phenomena such as lithium enrichment and alterations in many chemical abundances. In all cases, we know that stellar magnetism plays a
prominent role, although it is still far from being fully understood. In this thesis, we use
models computed with the Toulouse-Geneva Stellar Evolution Code (TGEC) to study the
rotational evolution of four samples of solar-type stars, in addition to revisiting studies with
analogous stars from open clusters. In our analysis, we used two different magnetic brake
prescriptions, which simulate the loss of angular momentum due to stellar winds. Additionally, we also studied a sample of giant solar-type stars that are lithium-rich, investigating
the possible relationship of the enrichment with the magnetic character of some of these
stars. As far as main sequence stars are concerned, we found some convergences and discrepancies between our models and the stellar samples studied. We found that the sample
with seismological data, composed of stars of intermediate and older ages, is not well constrained for a study on the rotation and magnetic evolution of the Sun. The sample of lowactivity stars appears to be affected by a decrease in magnetic braking despite differences
in metallicity, with targets with higher metallicity following closer our evolutionary tracks.
Finally, we found a mismatch between our rotation evolution tracks and the position of the
youngest stars. As for lithium-rich giant stars, we found that stars previously classified as
red giant branch (RGB) may be in a different evolutionary state. Furthermore, we found
that most stars in our sample with surface magnetic field detection show at least moderate
rotation speeds. However, we were unable to detect a magnetic field in two rapidly rotating
stars. Because of our small sample of magnetic giants, it is difficult to establish the linkage
between the presence of a surface magnetic field and the Li-enrichment phenomena in giant
stars. At last, we investigated questions regarding the radial velocity modulation for some
stars of this sample, which could be indicative of them being binary or multiple systems.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESO estudo da evolução rotacional do Sol e das estrelas do tipo solar é sem dúvidas
um dos campos da astrofísica estelar atualmente em maior evidência. Existem inúmeras
questões ainda longe de serem completamente compreendidas, o que torna a pesquisa nesse
campo intensa e dinâmica. Dentre essas questões estão a compreensão dos fenômenos que
influenciam o momento angular das estrelas durante sua formação, ainda na fase da PréSequência Principal; o entendimento dos mecanismos que atuam nos interiores estelares ao
longo da evolução, que acabam por determinar, por exemplo, o perfil de rotação de corpo
sólido observado no Sol; ou quais mecanismos de transporte atuam em estrelas evoluídas,
que passam por profundas mudanças em sua estrutura, e apresentam fenômenos peculiares
como o enriquecimento de lítio e alterações em diversas abundâncias químicas. Em todos
os casos, sabemos que o magnetismo estelar tem um papel de destaque, entretanto ainda
longe de ser completamente entendido. Nesta tese usamos modelos calculados com o Código de Evolução Estelar de Toulouse-Genebra (TGEC) para estudar a evolução rotacional
de quatro amostras de estrelas do tipo solar, além de revisitar estudos com estrelas análogas
de aglomerados abertos. Utilizamos em nossas análises duas prescrições distintas de freio
magnético, que simulam a perda de momento angular devidos aos ventos estelares. Adicionalmente, também estudamos uma amostra de estrelas gigantes do tipo solar que são ricas
em lítio, investigando a possível relação do fenômeno de enriquecimento com o caráter
magnético de algumas dessas estrelas. No que se refere às estrelas da sequência principal, encontramos algumas convergências e algumas discrepâncias entre os nossos modelos
e as amostras estelares estudadas. Descobrimos que a amostra com dados sismológicos,
composta por estrelas de idade intermediária e mais velhas, não está bem restrita para um
estudo sobre a rotação e evolução magnética do Sol. A amostra de estrelas de baixa atividade parece ser afetada por uma diminuição no freio magnético independentemente das
diferenças de metalicidade, estando os alvos com maior metalicidade mais próximos dos
nossos traçados evolutivos. Por fim, encontramos uma incompatibilidade entre nossos traçados de evolução da rotação e a posição das estrelas mais jovens. Já com relação às estrelas
gigantes ricas em lítio, descobrimos que estrelas anteriormente classificadas como no ramo
das gigantes vermelhas (RGB) podem estar em um estado evolutivo diferente. Além disso,
identificamos que a maioria das estrelas em nossa amostra com detecção de campo magnético superficial mostram velocidades de rotação pelo menos moderadas. Contudo, não
conseguimos detectar campo magnético superficial em duas estrelas com rotação rápida.
Por causa de nossa pequena amostra de gigantes magnéticas, é difícil estabelecer a ligação
entre a presença de campo magnético de superfície e o fenômeno de enriquecimento de Li
em estrelas gigantes. Finalmente, foram investigadas questões envolvendo a modulação da
velocidade radial para algumas estrelas dessa amostra, o que indicaria a possibilidade de
serem sistemas binários ou múltiplos
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