Estrelas magnéticas quimicamente peculiares: Evolução, oscilações e Imageamento Doppler

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas - Programa de Pós-Graduação em Física.Apresentamos nesta tese os resultados de três estudos observacionais relacionados com as estrelas Ap, assim como a sub-classe das estrelas rapidamente oscilantes (roAp). No primeiro estudo, investigamos o estado evolutivo das estrelas Ap visando responder a seguinte pergunta: as estrelas nascem peculiares, ou desenvolvem suas peculiaridades ao longo de sua vida na seqüência principal? Para isso, observamos e classificamos 470 estrelas pertencentes a 18 aglomerados com idades entre 6.9 < log t < 8.1 e estudamos a freqüência de ocorrência de estrelas Ap em função da idade dos aglomerados

Discovery of a new PG1159 (GW Vir) Pulsator

We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12+085232.18. Analysis of the spectrum by Werner, Rauch and Kepler (2014) indicated Teff=120 000+/-10 000 K, log g=7.0+/-0.3, mass M=0.52+/-0.02 Msun, C/He=0.33 by number. We obtained time-series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.Comment: 5 pages, 3 figure

Dinâmica econômica, bolhas especulativas e transformações estruturais: das inovações tecnológicas à instabilidade financeira

O objetivo geral deste artigo é apresentar, de acordo com as abordagens schumpeteriana e minskyana, um padrão da dinâmica capitalista e transformações estruturais a partir das interligações entre os processos de inovação das empresas da “Nova Economia” e seu financiamento entre 1995 e 2004 nos EUA. Apesar de a teoria schumpeteriana possuir uma explicação dos ciclos econômicos calcada nos impactos de um conjunto de inovações concentrados no tempo, a sua teoria não reconhece os efeitos dinâmicos da demanda efetiva relacionadas ao sofisticado desenvolvimento dos sistemas financeiros sobre as inovações, sendo fundamental a teoria de Hyman P. Minsky. Este trabalho evidencia que a economia estadunidense estava frágil financeiramente, principalmente porque a valorização dos ativos não aumentou na mesma proporção da capacidade da geração de lucros ou dividendos das empresas de alta tecnologia e, além disso, não havia lastro real das empresas de alta tecnologia em relação à capitalização de mercados, emissões de ações e volume de negócios

Spectroscopic study of the HII regions in the NGC 1232 galaxy

NGC 1232 is a face-on spiral galaxy that serves as an excellent laboratory for the study of star formation due to its proximity. Recent studies have revealed interesting features about this galaxy: X-ray observations suggest that it recently collided with a dwarf galaxy, however, no apparent remnant is observed. Here we search for evidence of this collision. We used long-slit optical spectra in two different positions obtained with the Goodman spectrograph at the SOAR telescope. We detected 18 HII regions in the north-south direction and 22 HII regions in the east-west direction and a background galaxy, NGC 1232B, for which we present the first redshift measurement and spectral analysis. We used the stellar population fitting technique to study the underlying stellar population and to subtract it from the spectra to measure the emission lines. The emission lines were used to determine the extinction, electron density, chemical abundance, and the star-formation rate gradient of NGC 1232. As is common in spiral galaxies, we found a stellar population gradient with older populations at the central regions and younger ones towards the outskirts, along with a negative oxygen abundance gradient of -0.16 dex/re. Due to the difficulty of measuring important emission lines, the number of objects for the abundance gradient is small, but there is a hint that this galaxy has a broken gradient profile, with a drop towards the center. If the collision caused any disturbance in the galaxy, we believe it would be small and hard to detect with a limited number of objects. From all the other measurements, we found no deviations from a typical spiral galaxy and no significant difference between different directions in the galaxy. The stellar population and emission line analysis of NGC 1232B suggest that it is a starburst galaxy.Comment: 18 pages and 16 figures + 14 pages with 14 figures in the appendix. Accepted for publication on A&

Diagnostic accuracy of oximetry for obstructive sleep apnea: a study on older adults in a home setting

OBJECTIVES: Owing to the fact that obstructive sleep apnea (OSA) is an underreported disease, the strategy used for the diagnosis of OSA has been extensively dissected to devise a simplified process that can be accessed by the public health services. Polysomnography (PSG) type I, the gold standard for the diagnosis of OSA, is expensive and difficult to access by low-income populations. In this study, we aimed to verify the accuracy of the oxyhemoglobin desaturation index (ODI) in comparison to the apnea-hypopnea index (AHI) using a portable monitor. METHODS: We evaluated 94 type III PSG home test results of 65 elderly patients (69.21±6.94 years old), along with information, such as the body mass index (BMI) and sex, using data obtained from a clinical trial database. RESULTS: A significant linear positive correlation (r=0.93,&nbsp;p&lt;0.05) was observed between ODI and AHI, without any interference from sex, BMI, and positional component. The sensitivity of ODI compared to that of AHI increased with an increase in the severity of OSA, while the specificity of ODI in comparison to that of AHI was high for all degrees of severity. The accuracy of ODI was 80.7% for distinguishing between patients with mild and moderate apnea and 84.4% for distinguishing between patients with moderate and severe apnea. CONCLUSION: The ODI values obtained in uncontrolled conditions exhibited high sensitivity for identifying severe apnea compared to the AHI values, and correctly identified the severity of OSA in more than 80% of the cases. Thus, oximetry is promising strategy for diagnosing OSA

Discovery of a new PG 1159 (GW Vir) pulsator

We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12 + 085232.18. Analysis of the spectrum by Werner et al. indicated Teff = 120 000 ± 10 000 K, log g = 7.0 ± 0.3, mass M = 0.52 ± 0.02M⊙, C/He = 0.33 by number. We obtained time series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.Facultad de Ciencias Astronómicas y Geofísica

Prandial correlations and structure of the ingestive behavior of pigs in precision feeding programs

The feeding behavior of growing-finishing pigs was analyzed to study prandial correlations and the probability of starting a new feeding event. The data were collected in real-time based on 157,632 visits by a group of 70 growing-finishing pigs (from 30.4 to 115.5 kg body weight, BW) to automatic feeders. The data were collected over 84 days, during which period the pigs were kept in conventional (by phase and by group) or precision (with daily and individual adjustments) feeding programs. A criterion to delimit each meal was then defined based on the probability of an animal starting a new feeding event within the next minute since the last visit. Prandial correlations were established between meal size and interval before meal (pre-prandial) or interval after meal (postprandial) using Pearson correlation analysis. Post-prandial correlations (which can be interpreted as hunger-regulating mechanisms) were slightly stronger than pre-prandial correlations (which can be interpreted as satiety regulation mechanisms). Both correlations decreased as the animals’ age increased but were little influenced by the feeding programs. The information generated in this study allows a better understanding of pigs’ feeding behavior regulation mechanisms and could be used in the future to improve precision feeding programs