3,670 research outputs found
WASP-33: The first delta Scuti exoplanet host star
We report the discovery of photometric oscillations in the host star of the
exoplanet WASP-33 b (HD 15082). The data were obtained in the R band in both
transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer
Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory.
Proper fitting and subsequent removal of the transit signal reveals stellar
photometric variations with a semi-amplitude of about 1 mmag. The detailed
analysis of the periodogram yields a structure of significant signals around a
frequency of 21 cyc per day, which is typical of delta Scuti-type variable
stars. An accurate study of the power spectrum reveals a possible
commensurability with the planet orbital motion with a factor of 26, but this
remains to be confirmed with additional time-series data that will permit the
identification of the significant frequencies. These findings make WASP-33 the
first transiting exoplanet host star with delta Sct variability and a very
interesting candidate to search for star-planet interactions.Comment: 5 pages, 6 figures. Revised version accepted for publication in A&A
Letter
Assessment of rural primary care clinics through the Patient Evaluation Advisory Tool
OBJECTIVE:To identify inefficiencies in a medical practice with the goal of creating a more efficient workflow from the perspective of the patient.METHODS:Human: Survey distribution and sentiment identificationSoftware: Statistical analysisRESULTS & CONCLUSIONS:According to the responses of patients of two rural primary care clinics, the results revealed areas of weakness and improvement centered around patient satisfaction. In addition to clinical staff, patients submitted their rating regarding all aspects of the clinic. The patient perspective is not currently being analyzed to transform workplace efficiencies, but this study aims to use the patient perspective insight to identify inefficiencies as well as deliver more patient-centered healthcare through the distribution of surveys
MOST observations of the roAp stars HD 9289, HD 99563, and HD 134214
We report on the analysis of high-precision space-based photometry of the
roAp (rapidly oscillating Ap) stars HD 9289, HD 99563, and HD134214. All three
stars were observed by the MOST satellite for more than 25 days, allowing
unprecedented views of their pulsation. We find previously unknown candidate
frequencies in all three stars. We establish the rotation period of HD 9289
(8.5 d) for the first time and show that the star is pulsating in two modes
that show different mode geometries. We present a detailed analysis of HD
99563's mode multiplet and find a new candidate frequency which appears
independent of the previously known mode. Finally, we report on 11 detected
pulsation frequencies in HD 134214, 9 of which were never before detected in
photometry, and 3 of which are completely new detections. Thanks to the
unprecedentedly small frequency uncertainties, the p-mode spectrum of HD 134214
can be seen to have a well-defined large frequency spacing similar to the
well-studied roAp star HD 24712 (HR 1217).Comment: 11 pages, 12 figures, accepted for publication in A&
Correlation between technetium and lithium in a sample of oxygen-rich AGB variables
The aims of this paper are: 1) to revisit the Tc content of a sample of
oxygen-rich asymptotic giant branch (AGB) variables and 2) to increase the
number of such stars for which the Li abundance has been measured to provide
constraints on theoretical models of extra-mixing processes. To this end, we
analysed high-resolution spectra of 18 sample stars for the presence of
absorption lines of Tc and Li. The abundance of the latter was determined by
comparing the observed spectra to hydrostatic MARCS model spectra. Bolometric
magnitudes were established from near-IR photometry and pulsation periods. We
reclassify the star V441 Cyg as Tc-rich, and the unusual Mira star R Hya, as
well as W Eri, as Tc-poor. The abundance of Li, or an upper limit to it, was
determined for all of the sample stars. In all stars with Tc we also detected
Li. Most of them have a Li content slightly below the solar photospheric value,
except for V441 Cyg, which has ~1000 times the solar abundance. We also found
that, similar to Tc, a lower luminosity limit seems to exist for the presence
of Li. We conclude that the higher Li abundance found in the cooler and higher
luminosity objects could stem from a Li production mechanism operating on the
AGB. The stellar mass might have a crucial influence on this (extra-mixing)
production mechanism. It was speculated that the declining pulsation period of
R Hya is caused by a recent thermal pulse (TP). While not detecting Tc does not
rule out a TP, it indicates that the TPs are not strong enough to drive
dredge-up in R Hya. V441 Cyg, on the other hand, could either be a low-mass,
intrinsic S-star that produced its large amount of Li by extra-mixing
processes, or an intermediate-mass star (M>=M_sun) undergoing Li production due
to hot bottom burning.Comment: 12 pages, 7 figures, accepted for publication in A&
Systemic lupus erythematosus associated with type 4 renal tubular acidosis: a case report and review of the literature
The evolutionary state of Miras with changing pulsation periods
Context: Miras are long-period variables thought to be in the asymptotic
giant branch (AGB) phase of evolution. In about one percent of known Miras, the
pulsation period is changing. It has been speculated that this changing period
is the consequence of a recent thermal pulse in these stars. Aims: We aim to
clarify the evolutionary state of these stars, and to determine in particular
whether or not they are in the thermally-pulsing (TP-)AGB phase. Methods: One
important piece of information that has been neglected so far when determining
the evolutionary state is the presence of the radio-active s-process element
technetium (Tc). We obtained high-resolution, high signal-to-noise-ratio
optical spectra of a dozen prominent Mira variables with changing pulsation
period to search for this indicator of TPs and dredge-up. We also use the
spectra to measure lithium (Li) abundances. Furthermore, we establish the
evolutionary states of our sample stars by means of their present-day periods
and luminosities. Results: Among the twelve sample stars observed in this
programme, five were found to show absorption lines of Tc. BH Cru is found to
be a carbon-star, its period increase in the past decades possibly having
stopped by now. We report a possible switch in the pulsation mode of T UMi from
Mira-like to semi-regular variability in the past two years. R Nor, on the
other hand, is probably a fairly massive AGB star, which could be true for all
meandering Miras. Finally, we assign RU Vul to the metal-poor thick disk with
properties very similar to the short-period, metal-poor Miras. Conclusions: We
conclude that there is no clear correlation between period change class and Tc
presence. The stars that are most likely to have experienced a recent TP are BH
Cru and R Hya, although their rates of period change are quite different.Comment: 11 pages, 7 figures, 2 tables; accepted for publication in A&
The secondary eclipse of CoRoT-1b
The transiting planet CoRoT-1b is thought to belong to the pM-class of
planets, in which the thermal emission dominates in the optical wavelengths. We
present a detection of its secondary eclipse in the CoRoT white channel data,
whose response function goes from ~400 to ~1000 nm. We used two different
filtering approaches, and several methods to evaluate the significance of a
detection of the secondary eclipse. We detect a secondary eclipse centered
within 20 min at the expected times for a circular orbit, with a depth of
0.016+/-0.006%. The center of the eclipse is translated in a 1-sigma upper
limit to the planet's eccentricity of ecosomega<0.014. Under the assumption of
a zero Bond Albedo and blackbody emission from the planet, it corresponds to a
T_{CoRoT}=2330 +120-140 K. We provide the equilibrium temperatures of the
planet as a function of the amount of reflected light. If the planet is in
thermal equilibrium with the incident flux from the star, our results imply an
inefficient transport mechanism of the flux from the day to the night sides.Comment: 6 pages, to appear in A&A, submitted 18 march 2009, accepted 7 July
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The Role of Muscle Perfusion in the Age-Associated Decline of Mitochondrial Function in Healthy Individuals
Maximum oxidative capacity of skeletal muscle measured by in vivo phosphorus magnetic resonance spectroscopy (31P-MRS) declines with age, and negatively affects whole-body aerobic capacity. However, it remains unclear whether the loss of oxidative capacity is caused by reduced volume and function of mitochondria or limited substrate availability secondary to impaired muscle perfusion. Therefore, we sought to elucidate the role of muscle perfusion on the age-related decline of muscle oxidative capacity and ultimately whole-body aerobic capacity. Muscle oxidative capacity was assessed by 31P-MRS post-exercise phosphocreatine recovery time (ĎPCr), with higher ĎPCr reflecting lower oxidative capacity, in 75 healthy participants (48 men, 22-89 years) of the Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing study. Muscle perfusion was characterized as an index of blood volume at rest using a customized diffusion-weighted MRI technique and analysis method developed in our laboratory. Aerobic capacity (peak-VO2) was also measured during a graded treadmill exercise test in the same visit. Muscle oxidative capacity, peak-VO2, and resting muscle perfusion were significantly lower at older ages independent of sex, race, and body mass index (BMI). ĎPCr was significantly associated with resting muscle perfusion independent of age, sex, race, and BMI (p-value = 0.004, β = -0.34). ĎPCr was also a significant independent predictor of peak-VO2 and, in a mediation analysis, significantly attenuated the association between muscle perfusion and peak-VO2 (34% reduction for β in perfusion). These findings suggest that the age-associated decline in muscle oxidative capacity is partly due to impaired muscle perfusion and not mitochondrial dysfunction alone. Furthermore, our findings show that part of the decline in whole-body aerobic capacity observed with aging is also due to reduced microvascular blood volume at rest, representing a basal capacity of the microvascular system, which is mediated by muscle oxidative capacity. This finding suggests potential benefit of interventions that target an overall increase in muscle perfusion for the restoration of energetic capacity and mitochondrial function with aging
An astrophysical interpretation of the remarkable g-mode frequency groups of the rapidly rotating Îł Dor star, KIC 5608334
The Fourier spectrum of the Îł-Dor variable KIC 5608334 shows remarkable frequency groups at âź3, âź6, âź9, and 11â12 dâ1. We explain the four frequency groups as prograde sectoral g modes in a rapidly rotating star. Frequencies of intermediate-to-high radial order prograde sectoral g modes in a rapidly rotating star are proportional to |m| (i.e. νâ|m|) in the corotating frame as well as in the inertial frame. This property is consistent with the frequency groups of KIC 5608334 as well as the period versus period-spacing relation present within each frequency group, if we assume a rotation frequency of 2.2 dâ1, and that each frequency group consists of prograde sectoral g modes of |m| = 1, 2, 3, and 4, respectively. In addition, these modes naturally satisfy near-resonance conditions νi â νj + νk with mi = mj + mk. We even find exact resonance frequency conditions (within the precise measurement uncertainties) in many cases, which correspond to combination frequencies
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Factors associated with self-efficacy for managing recovery in the trauma intensive care population: A prospective cohort study
Objective: The aim of this paper was to identify factors associated with self-efficacy for managing recovery in the trauma intensive care population.
Introduction: Injury accounts for 6.5% of disease burden in Australia, with similar levels being reported in other developed countries. While some studies regarding self-efficacy have identified a relationship to patient recovery post acute injury, others have been inconclusive. This study will identify factors associated with self-efficacy for managing recovery in the trauma intensive care population.
Methods: A prospective cohort study of patients aged âĽ18 years, admitted to a metropolitan tertiary hospital in South East Queensland between June 2008 and August 2010 for the acute treatment of injury. Demographic, injury, acute care and psychosocial factors were considered. The primary outcome was self-efficacy measured by the 6-item self-efficacy scale (SES) 1 and 6 months post hospital discharge. All factors significant (p < 0.10) on univariate analysis were included in multivariable modelling where p < 0.05 was considered significant.
Results: A total of 88 patients were included. The mean self-efficacy score at 1 and 6 months was similar (6.8 vs 6.9 respectively). Self-efficacy at 1 month, psychological distress (K-10) Score and illness perception (K10) Score accounted for 68.4% (adjusted R2) of the variance in 6 month self-efficacy (F3,75) = 57.17, p < 0.001. Illness perception was the strongest contributor to 6 month self-efficacy (beta = â0.516), followed by psychological distress (beta = â0.243) and self-efficacy at 1 month (beta = 0.205).
Conclusion: Significant factors associated with self-efficacy for managing recovery at 6 months included 1 month self-efficacy, illness perception and psychological distress. To promote patient recovery, screening patients at 1 month in order to commence relevant interventions could be beneficial
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