136 research outputs found
Application of Monte Carlo-based statistical significance determinations to the Beta Cephei stars V400 Car, V401 Car, V403 Car and V405 Car
We have used Lomb-Scargle periodogram analysis and Monte Carlo significance
tests to detect periodicities above the 3-sigma level in the Beta Cephei stars
V400 Car, V401 Car, V403 Car and V405 Car. These methods produce six previously
unreported periodicities in the expected frequency range of excited pulsations:
one in V400 Car, three in V401 Car, one in V403 Car and one in V405 Car. One of
these six frequencies is significant above the 4-sigma level. We provide
statistical significances for all of the periodicities found in these four
stars.Comment: 11 pages, 17 figure
Ostial plication: a rarely reported cause of sudden death
We report a rare case of ostial plication as a potential cause of sudden death. Very few reports and images are available in the specialized literature regarding this anomaly. Ostial plication may be a source of sudden death or cause of death when no other significant autopsy findings are present
Germinação de Eragrostis plana Nees sob efeito do extrato de Achyrocline satureioides (Lam.) DC.
Resumo 31
Plaskett's Star: Analysis of the CoRoT photometric data
The SRa02 of the CoRoT space mission for Asteroseismology was partly devoted
to stars belonging to the Mon OB2 association. An intense monitoring was
performed on Plaskett's Star (HD47129) and the unprecedented quality of the
light curve allows us to shed new light on this very massive, non-eclipsing
binary system. We particularly aimed at detecting periodic variability which
might be associated with pulsations or interactions between both components. We
also searched for variations related to the orbital cycle which could help to
constrain the inclination and the morphology of the binary system. A
Fourier-based prewhitening and a multiperiodic fitting procedure were applied
to analyse the time series and extract the frequencies of variations. We
describe the noise properties to tentatively define an appropriate significance
criterion, to only point out the peaks at a certain significance level. We also
detect the variations related to the orbital motion and study them by using the
NIGHTFALL program. The periodogram exhibits a majority of peaks at low
frequencies. Among these peaks, we highlight a list of about 43 values,
including notably two different sets of harmonic frequencies whose fundamental
peaks are located at about 0.07 and 0.82d-1. The former represents the orbital
frequency of the binary system whilst the latter could probably be associated
with non-radial pulsations. The study of the 0.07d-1 variations reveals the
presence of a hot spot most probably situated on the primary star and facing
the secondary. The investigation of this unique dataset constitutes a further
step in the understanding of Plaskett's Star. These results provide a first
basis for future seismic modelling. The existence of a hot region between both
components renders the determination of the inclination ambiguous.Comment: Accepted in A&A, 13 pages, 7 figures, 2 table
Determination of rotation periods in solar-like stars with irregular sampling: the Gaia case
We present a study on the determination of rotation periods (P) of solar-like
stars from the photometric irregular time-sampling of the ESA Gaia mission,
currently scheduled for launch in 2013, taking into account its dependence on
ecliptic coordinates. We examine the case of solar-twins as well as thousands
of synthetic time-series of solar-like stars rotating faster than the Sun. In
the case of solar twins we assume that the Gaia unfiltered photometric passband
G will mimic the variability of the total solar irradiance (TSI) as measured by
the VIRGO experiment. For stars rotating faster than the Sun, light-curves are
simulated using synthetic spectra for the quiet atmosphere, the spots, and the
faculae combined by applying semi-empirical relationships relating the level of
photospheric magnetic activity to the stellar rotation and the Gaia
instrumental response. The capabilities of the Deeming, Lomb-Scargle, and Phase
Dispersion Minimisation methods in recovering the correct rotation periods are
tested and compared. The false alarm probability (FAP) is computed using Monte
Carlo simulations and compared with analytical formulae. The Gaia scanning law
makes the rate of correct detection of rotation periods strongly dependent on
the ecliptic latitude (beta). We find that for P ~ 1 d, the rate of correct
detection increases with ecliptic latitude from 20-30 per cent at beta ~
0{\deg} to a peak of 70 per cent at beta=45{\deg}, then it abruptly falls below
10 per cent at beta > 45{\deg}. For P > 5 d, the rate of correct detection is
quite low and for solar twins is only 5 per cent on average.Comment: 12 pages, 18 figures, accepted by MNRA
Single coronary artery from the right sinus of Valsalva
We describe a case of a single coronary artery originating from the right coronary sinus and bifurcating into the left coronary artery (LCA) and right coronary artery (RCA) in a 74-year old woman, with a non-ST elevation acute myocardial infarction (NSTEMI). Diagnosis was made by coronary angiography which ruled out stenosis, and showed normal LCA and RCA branching. The connection path of LCA, with the opposite cusp, was defined retroaortic by multislice computed tomography (CT). The variants of this coronary anomaly, together with their clinical implications and pathophysiology of acute myocardial infarction (AMI) are discussed. Multislice CT is fundamental for clinical decision making
CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data
We search for new variable B-type pulsators in the CoRoT data assembled
primarily for planet detection, as part of CoRoT's Additional Programme. We aim
to explore the properties of newly discovered B-type pulsators from the
uninterrupted CoRoT space-based photometry and to compare them with known
members of the Beta Cep and slowly pulsating B star (SPB) classes. We developed
automated data analysis tools that include algorithms for jump correction,
light-curve detrending, frequency detection, frequency combination search, and
for frequency and period spacing searches. Besides numerous new, classical,
slowly pulsating B stars, we find evidence for a new class of low-amplitude
B-type pulsators between the SPB and Delta Sct instability strips, with a very
broad range of frequencies and low amplitudes, as well as several slowly
pulsating B stars with residual excess power at frequencies typically a factor
three above their expected g-mode frequencies. The frequency data we obtained
for numerous new B-type pulsators represent an appropriate starting point for
further theoretical analyses of these stars, once their effective temperature,
gravity, rotation velocity, and abundances will be derived spectroscopically in
the framework of an ongoing FLAMES survey at the VLT.Comment: 22 pages, 30 figures, accepted for publication in A&
Kepler observations of variability in B-type stars
The analysis of the light curves of 48 B-type stars observed by Kepler is
presented. Among these are 15 pulsating stars, all of which show low
frequencies characteristic of SPB stars. Seven of these stars also show a few
weak, isolated high frequencies and they could be considered as SPB/beta Cep
hybrids. In all cases the frequency spectra are quite different from what is
seen from ground-based observations. We suggest that this is because most of
the low frequencies are modes of high degree which are predicted to be unstable
in models of mid-B stars. We find that there are non-pulsating stars within the
beta Cep and SPB instability strips. Apart from the pulsating stars, we can
identify stars with frequency groupings similar to what is seen in Be stars but
which are not Be stars. The origin of the groupings is not clear, but may be
related to rotation. We find periodic variations in other stars which we
attribute to proximity effects in binary systems or possibly rotational
modulation. We find no evidence for pulsating stars between the cool edge of
the SPB and the hot edge of the delta Sct instability strips. None of the stars
show the broad features which can be attributed to stochastically-excited modes
as recently proposed. Among our sample of B stars are two chemically peculiar
stars, one of which is a HgMn star showing rotational modulation in the light
curve.Comment: 19 pages, 11 figures, 4 table
Modeling the epidemiological impact of the UNAIDS 2025 targets to end AIDS as a public health threat by 2030
Background: UNAIDS has established new program targets for 2025 to achieve the goal of eliminating AIDS as a public health threat by 2030. This study reports on efforts to use mathematical models to estimate the impact of achieving those targets. // Methods and findings: We simulated the impact of achieving the targets at country level using the Goals model, a mathematical simulation model of HIV epidemic dynamics that includes the impact of prevention and treatment interventions. For 77 high-burden countries, we fit the model to surveillance and survey data for 1970 to 2020 and then projected the impact of achieving the targets for the period 2019 to 2030. Results from these 77 countries were extrapolated to produce estimates for 96 others. Goals model results were checked by comparing against projections done with the Optima HIV model and the AIDS Epidemic Model (AEM) for selected countries. We included estimates of the impact of societal enablers (access to justice and law reform, stigma and discrimination elimination, and gender equality) and the impact of Coronavirus Disease 2019 (COVID-19). Results show that achieving the 2025 targets would reduce new annual infections by 83% (71% to 86% across regions) and AIDS-related deaths by 78% (67% to 81% across regions) by 2025 compared to 2010. Lack of progress on societal enablers could endanger these achievements and result in as many as 2.6 million (44%) cumulative additional new HIV infections and 440,000 (54%) more AIDS-related deaths between 2020 and 2030 compared to full achievement of all targets. COVID-19–related disruptions could increase new HIV infections and AIDS-related deaths by 10% in the next 2 years, but targets could still be achieved by 2025. Study limitations include the reliance on self-reports for most data on behaviors, the use of intervention effect sizes from published studies that may overstate intervention impacts outside of controlled study settings, and the use of proxy countries to estimate the impact in countries with fewer than 4,000 annual HIV infections. // Conclusions: The new targets for 2025 build on the progress made since 2010 and represent ambitious short-term goals. Achieving these targets would bring us close to the goals of reducing new HIV infections and AIDS-related deaths by 90% between 2010 and 2030. By 2025, global new infections and AIDS deaths would drop to 4.4 and 3.9 per 100,000 population, and the number of people living with HIV (PLHIV) would be declining. There would be 32 million people on treatment, and they would need continuing support for their lifetime. Incidence for the total global population would be below 0.15% everywhere. The number of PLHIV would start declining by 2023
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) presenting with ventricular fibrillation in an adult: a case report
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly. The usual clinical course is severe left sided heart failure and mitral valve insufficiency presenting during the first months of life. However, in some cases collateral blood supply from the right coronary artery is sufficient and symptoms may be subtle or even absent. Arrhythmias or sudden cardiac death in adult life may be the first clinical presentation in patients with ALCAPA. We report a case, where a 39-year old woman presented with ventricular fibrillation during phycial exertion. Coronary angiography and CT-angiography revealed an anomalous origin of the left coronary artery, and an aortic reimplantation of the left coronary artery was performed followed by ICD implantation. A review of the literature on ALCAPA is presented along with CT images before and after surgery
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