Triangle-generation in topological D-brane categories

Tachyon condensation in topological Landau-Ginzburg models can generally be studied using methods of commutative algebra and properties of triangulated categories. The efficiency of this approach is demonstrated by explicitly proving that every D-brane system in all minimal models of type ADE can be generated from only one or two fundamental branes.Comment: 34 page

Search for sterile neutrino mixing in the MINOS long-baseline experiment

A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿µ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿µ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles ¿24 and ¿34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1×10-12¿¿s/eV at 90% C.L

The sexuality of HIV-positive adolescents: rights and challenges for healthcare

Sexualidade e saúde reprodutiva configuram questões relevantes para o cuidado integral à saúde de pessoas vivendo com HIV. Políticas públicas e serviços de saúde, entretanto, têm dedicado insuficiente atenção ao assunto. O objetivo deste trabalho é compreender como adolescentes e jovens soropositivos lidam com suas experiências sexuais e projetos de namoro, desejo de constituir família e de ter filhos. O estudo qualitativo entrevistou em profundidade 21 adolescentes vivendo com HIV (por transmissão vertical, sexual ou sanguínea) e 13 cuidadores de crianças e jovens, vivendo em São Paulo e em Santos, Brasil. As narrativas descrevem como aprenderam a lidar com a sexualidade e a ansiedade da revelação do diagnóstico nesse contexto. Destacam-se nas narrativas o despreparo, a desinformação sobre prevenção e a falta de apoio para lidar com a situação, assim como o estigma e a discriminação que atravessa grande parte das dificuldades relatadas. O artigo discute criticamente alguns dos desafios postos para uma adequada atenção à questão no Brasil, especialmente a consideração de jovens soropositivos como sujeitos de direitos sexuais, sugerindo diretrizes para a incorporação desta temática a um cuidado integral e humanizado de crianças e jovens vivendo com HIV.Sexuality and reproductive healthcare represent relevant issues for comprehensive care of HIV-positive adolescents. However, public policies and health services give this issue insufficient attention. The scope of this article is to assess how HIV-positive young people and teenagers cope with their sexuality, dating and the urge to have children and start a family. In a qualitative study, in-depth interviews were staged with 21 HIV-positive (contracted by vertical, sexual or intravenous transmission) teenagers and 13 caregivers of children and youths living in Sao Paulo and Santos. The interviews revealed the different ways teenagers cope with their sexuality and with the anxiety of HIV disclosure in this context. Lack of information about HIV prevention, lack of support and skills to cope with their sexuality were revealed in the reports. Furthermore, stigma and discrimination were the most frequently reported difficulties. The main challenges to be faced in Brazil in regard to this issue are discussed, especially the need to consider HIV-positive youth as entitled to sexual rights. Recommendations are also made for incorporating the issue into a humanized and comprehensive care approach for HIV-positive children and young people

Modeling the Subsurface Structure of Sunspots

While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this paper, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out an helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by \citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic

X-Ray Spectroscopy of Stars

(abridged) Non-degenerate stars of essentially all spectral classes are soft X-ray sources. Low-mass stars on the cooler part of the main sequence and their pre-main sequence predecessors define the dominant stellar population in the galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense, of X-ray spectra from the solar corona. X-ray emission from cool stars is indeed ascribed to magnetically trapped hot gas analogous to the solar coronal plasma. Coronal structure, its thermal stratification and geometric extent can be interpreted based on various spectral diagnostics. New features have been identified in pre-main sequence stars; some of these may be related to accretion shocks on the stellar surface, fluorescence on circumstellar disks due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot stars clearly dominate the interaction with the galactic interstellar medium: they are the main sources of ionizing radiation, mechanical energy and chemical enrichment in galaxies. High-energy emission permits to probe some of the most important processes at work in these stars, and put constraints on their most peculiar feature: the stellar wind. Here, we review recent advances in our understanding of cool and hot stars through the study of X-ray spectra, in particular high-resolution spectra now available from XMM-Newton and Chandra. We address issues related to coronal structure, flares, the composition of coronal plasma, X-ray production in accretion streams and outflows, X-rays from single OB-type stars, massive binaries, magnetic hot objects and evolved WR stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures (partly multiple); some corrections made after proof stag

Neutrino Masses and Mixing: Evidence and Implications

Measurements of various features of the fluxes of atmospheric and solar neutrinos have provided evidence for neutrino oscillations and therefore for neutrino masses and mixing. We review the phenomenology of neutrino oscillations in vacuum and in matter. We present the existing evidence from solar and atmospheric neutrinos as well as the results from laboratory searches, including the final status of the LSND experiment. We describe the theoretical inputs that are used to interpret the experimental results in terms of neutrino oscillations. We derive the allowed ranges for the mass and mixing parameters in three frameworks: First, each set of observations is analyzed separately in a two-neutrino framework; Second, the data from solar and atmospheric neutrinos are analyzed in a three active neutrino framework; Third, the LSND results are added, and the status of accommodating all three signals in the framework of three active and one sterile light neutrinos is presented. We review the theoretical implications of these results: the existence of new physics, the estimate of the scale of this new physics and the lessons for grand unified theories, for supersymmetric models with R-parity violation, for models of extra dimensions and singlet fermions in the bulk, and for flavor models.Comment: Added note on the effects of KamLAND results. Two new figure

Atraso na introdução de terapia antiretroviral em pacientes infectados pelo HIV no Brasil, 2003-2006

PURPOSE: To characterize the population of HIV+ Brazilian patients with late introduction of antiretroviral therapy (ARVT), using information from the Laboratory Exam Control System. METHODS: The study analyzed 84,694 patients, representing all individuals in Brazil age 15 or over with an initial CD4+ T lymphocyte count requested between 2003 and 2006, and whose ARVT start date was later than their initial CD4+ T cell count. These patients were considered antiretroviral treatment naive. The initial CD4+ T cell distribution was analyzed according to sex, age, region and year. RESULTS: Most of the patients were between 15 and 49 years of age (91%); 56% were males; 76% were asymptomatic; 50% lived in the Southeastern region of the country, with an additional 20% in the South. Initial CD4+ counts for one-third of the patients were less than 200 cells/mm³. When combined with the number of symptomatic individuals, 41% of the total group was in need of immediate ARVT. This group included 47% of the men and 53% of the patients aged 50 years and over. CONCLUSIONS: Despite universal access to ARVT in Brazil, results show that a high proportion of patients initiate ARVT at an advanced stage of disease, indicating the need to develop strategies to promote early diagnosis of HIV infection nationwide.OBJETIVO: Caracterizar a população de indivíduos infectados pelo HIV que inicia tardiamente a terapia com anti-retrovirais (TARV) no Brasil, utilizando informações do Sistema de Controle de Exames Laboratoriais. MÉTODOS: Foram analisados todos os indivíduos de 15 anos ou mais de idade que realizaram exame inicial para contagem de linfócitos T CD4+ para avaliação de indicação de tratamento entre os anos de 2003 e 2006, cuja data de início da terapia foi posterior ou igual à data de solicitação da contagem de células T CD4+ (84694 pacientes). Esses pacientes foram considerados como virgens de tratamento com anti-retrovirais. A distribuição da contagem inicial de linfócitos T CD4+ foi analisada por sexo, idade, Grande Região e ano de realização do exame. RESULTADOS: A maioria dos pacientes tinha entre 15 e 49 anos de idade (91%); 56% eram do sexo masculino; 76% assintomáticos; 50% residiam na Região Sudeste e 20% na Região Sul. A proporção de indivíduos cujo resultado do primeiro exame para contagem de linfócitos TCD4+ era inferior a 200 cel/mm³ foi de 33%. Somando-se a esses os indivíduos sintomáticos, o valor atinge 41% para a totalidade; 47% para os homens e 53% para os pacientes com mais de 50 anos de idade. CONCLUSÕES: Em que pese o acesso universal à TARV, no Brasil, os resultados mostram que uma alta proporção de pacientes inicia o tratamento em um estádio avançado da doença, apontando para a necessidade do estabelecimento de estratégias de diagnóstico precoce da infecção pelo HIV