224 research outputs found

    The Red Supergiant Progenitor of Supernova 2012aw (PTF12bvh) in Messier 95

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    We report on the direct detection and characterization of the probable red supergiant (RSG) progenitor of the intermediate-luminosity Type II-Plateau (II-P) supernova (SN) 2012aw in the nearby (10.0 Mpc) spiral galaxy Messier 95 (M95; NGC 3351). We have identified the star in both Hubble Space Telescope images of the host galaxy, obtained 17-18 yr prior to the explosion, and near-infrared ground-based images, obtained 6-12 yr prior to the SN. The luminous supergiant showed evidence for substantial circumstellar dust, manifested as excess line-of-sight extinction. The effective total-to-selective ratio of extinction to the star was R'_V ≈ 4.35, which is significantly different from that of diffuse interstellar dust (i.e., R_V = 3.1), and the total extinction to the star was therefore, on average, A_V ≈ 3.1 mag. We find that the observed spectral energy distribution for the progenitor star is consistent with an effective temperature of 3600 K (spectral type M3), and that the star therefore had a bolometric magnitude of –8.29. Through comparison with recent theoretical massive-star evolutionary tracks we can infer that the RSG progenitor had an initial mass 15 ≲ M_(ini)(M_☉) < 20. Interpolating by eye between the available tracks, we surmise that the star had initial mass ~17-18 M_☉. The circumstellar dust around the progenitor must have been destroyed in the explosion, as the visual extinction to the SN is found to be low (AV = 0.24 mag with R_V = 3.1)

    Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates

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    We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASSJ19104752+4220194. We find a stellar effective temperature Teff=5455+-100K, a metallicity of [Fe/H]=0.01+-0.04, and a surface gravity of log(g)=4.4+-0.1. Combined with an estimate of the stellar density from the transit light curves we deduce a stellar mass of Mstar=0.912+-0.034 Msun and a stellar radius of Rstar=0.944^{+0.060}_{-0.095} Rsun. For three of the transit signals, our results strongly disfavor the possibility that these result from astrophysical false positives. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2e5 (Kepler-20b), 1e5 (Kepler-20c), and 1.1e3 (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: From Spitzer data gathered at 4.5um, we infer a ratio of the planetary to stellar radii of 0.075+-0.015 (Kepler-20c) and 0.065+-0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70d and 1.91^{+0.12}_{-0.21} Rearth for Kepler-20b, 10.85 d and 3.07^{+0.20}_{-0.31} Rearth for Kepelr-20c, and 77.61 d and 2.75^{+0.17}_{-0.30} Rearth for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7\+-2.2 Mearth and 16.1+-3.5 Mearth, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 Mearth (2 sigma).Comment: accepted by ApJ, 58 pages, 12 figures revised Jan 2012 to correct table 2 and clarify planet parameter extractio

    Síntomas de pacientes antes de la primera hospitalización por Síndrome Coronario Agudo

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    Este estudo objetivou caracterizar os pacientes quanto ao relato da presença de sintomas de dor torácica, dispneia e limitação das atividades diárias uma semana antes da primeira hospitalização por Síndrome Coronariana Aguda, segundo a forma de apresentação clínica, e compará-las. Estudo transversal, descritivo e correlacional. Utilizou-se um instrumento de avaliação clínica que investigou a presença e a gravidade dos sintomas de dispneia, precordialgia e restrição física decorrentes da isquemia do miocárdio. Com relação à limitação para realização de atividades físicas, pacientes com diagnóstico de angina instável mostraram maior comprometimento na semana que antecedeu a internação, assim como relataram a presença de dispneia e precordialgia com maior frequência do que os pacientes infartados em situações que vão desde realizarem grandes esforços como, por exemplo, caminhar na subida ou muito rápido no plano, até situações de repouso ou de pequenos esforços.The objective of this study was to characterize and compare patients regarding their report of experiencing chest pain, dyspnea and limitation of the daily life activities one week before their first hospitalization due to Acute Coronary Syndrome, according to the clinical presentation form, and compare them. This is a cross-sectional, descriptive and correlational study. A clinical evaluation instrument was used to investigate the presence and severity of dyspnea, chest pain and physical restriction due to myocardial ischemia. Regarding the limitation to carry out physical activities, patients diagnosed with unstable angina showed lower capacity the week before hospitalization, and reported experiencing dyspnea and chest pain more frequently than patients who had an infarction in situations ranging from making strong efforts, such as walking uphill or on a flat surface but very quickly, to resting and in situations of little effort.Estudio que objetivó caracterizar a pacientes en cuanto al relato de presencia de síntomas de dolor torácico, disnea y limitación de actividades diarias una semana antes de la primera hospitalización por Síndrome Coronario Agudo, según la forma de presentación clínica, y compararlas. Estudio transversal, descriptivo y correlacional. Se utilizó un instrumento de evaluación clínica que investigó la presencia y gravedad de síntomas de disnea, precordialgia y restricción física derivadas de isquemia de miocardio. En relación a limitaciones para realización de actividades físicas, pacientes con diagnóstico de angina inestable mostraron mayor compromiso en la semana que antecedió a la internación, así como relataron la presencia de disnea y precordialgia con mayor frecuencia que en los pacientes infartados en situaciones tales como realizar grandes esfuerzos como, por ejemplo, caminar en pendiente ascendiente o muy rápido en el llano, hasta situaciones de reposo o pequeños esfuerzos

    Becoming the temporary surgeon: A grounded theory examination of anaesthetists performing emergency front of neck access in inter-disciplinary simulation based training

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    The time-critical 'can't intubate, can't oxygenate' [CICO] emergency post-induction of anaesthesia is rare, but one which, should it occur, requires Anaesthetists to perform rapid emergency front of neck access [FONA] to the trachea, restoring oxygenation, and preventing death or brain hypoxia. The UK Difficult Airway Society [DAS] has directed all Anaesthetists to be trained with surgical cricothyroidotomy [SCT] as the primary emergency FONA method, sometimes referred to as 'Cric' as a shorthand. We present a longitudinal analysis using a classical approach to Grounded Theory methodology of ten Specialist Trainee Anaesthetists' data during a 6-month training programme delivered jointly by Anaesthetists and Surgeons. We identified with a critical realist ontology and an objectivist epistemology meaning data interpretation was driven by participants' narratives and accepted as true accounts of their experience. Our theory comprises three themes: 'Identity as an Anaesthetist'; 'The Role of a Temporary Surgeon'; and 'Training to Reconcile Identities', whereby training facilitated the psychological transition from a 'bloodless Doctor' (Anaesthetist) to becoming a 'temporary Surgeon'. The training programme enabled Specialist Trainees to move between the role of control and responsibility (Identity as an Anaesthetist), through self-described 'failure' and into a role of uncertainty about one's own confidence and competence (The Role of a Temporary Surgeon), and then return to the Anaesthetist's role once the airway had been established. Understanding the complexity of an intervention and providing a better insight into the training needs of Anaesthetic trainees, via a Grounded Theory approach, allows us to evaluate training programmes against the recognised technical and non-technical needs of those being trained

    Resource allocation of in vitro fertilization: a nationwide register-based cohort study

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    <p>Abstract</p> <p>Background</p> <p>Infertility is common and in vitro fertilization (IVF) is a widely used treatment. In IVF the need increases and the effectiveness and appropriateness decrease by age. The purpose of this study was to describe allocation of resources for IVF by women's age, socioeconomic position, area of residence and treatment sector (public vs. private) and to discuss how fairly the IVF resources are allocated in Finland.</p> <p>Methods</p> <p>Women who received IVF between 1996 and 1998 (N = 9175) were identified from the reimbursement records of the Social Insurance Institution (SII). Information on IVF women's background characteristics came from the Central Population Register and the SII, on treatment costs from IVF clinics and the SII, and on births from the Medical Birth Register. The main outcome measures were success of IVF by number of cycles and treated women, expenditures per IVF cycles, per women, per live-birth, and per treatment sector, and private and public expenditures. Expenditures were estimated from health care visits and costs.</p> <p>Results</p> <p>During a mean period of 1.5 years, older women (women aged 40 or older) received 1.4 times more IVF treatment cycles than younger women (women aged below 30). The success rate decreased by age: from 22 live births per 100 cycles among younger women to 6 per 100 among older women. The mean cost of a live birth increased by age: compared to younger women, costs per born live birth of older women were 3-fold. Calculated by population, public expenditure was allocated most to young women and women from the highest socioeconomic position. Regional differences were not remarkable.</p> <p>Conclusion</p> <p>Children of older infertile women involve more expense due to the lower success rates of IVF. Socioeconomic differences suggest unfair resource allocation in Finland.</p
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