91 research outputs found
Asteroseismology from space: The δ Scuti star θ^2 Tauri monitored by the WIRE satellite
The bright variable star θ^2 Tau was monitored with the star camera on the Wide–Field Infrared Explorer satellite. Twelve independent frequencies were detected down to the 0.5 mmag amplitude level. Their reality was investigated by searching for them using two different algorithms and by some internal checks: both procedures strengthened our confidence in the results. All the frequencies are in the range 10.8–14.6 cd^(-1). The histogram of the frequency spacings shows that 81% are below 1.8 cd^(-1); rotation may thus play a role in the mode excitation. The fundamental radial mode is not observed, although it is expected to occur in a region where the noise level is very low (55 μmag). The rms residual is about two times lower than that usually obtained from successful ground–based multisite campaigns. The comparison of the results of previous campaigns with the new ones establishes the amplitude variability of some modes
Asteroseismology from space: the Delta Scuti star Theta2 Tauri monitored by the WIRE satellite
The first intensive photometric time-series of a Delta Scuti star was
obtained from space. Theta2 Tau was monitored with the star camera on the
Wide-Field Infrared Explorer (WIRE) satellite. Twelve independent frequencies
were detected down to the 0.5 mmag amplitude level. Their reality was
investigated by searching for them using two different algorithms and by some
internal checks. All the frequencies are in the range 10.8-14.6 c\d. The
histogram of the frequency spacings shows that 81% are below 1.8 c\d; rotation
may thus play a role in the mode excitation. The fundamental radial mode is not
observed, although it is expected to occur in a region where the noise level is
very low (55 micromag). The rms residual is about two times lower than that
usually obtained from successful ground--based multisite campaigns. The
comparison of the results of previous campaigns with the new ones establishes
the amplitude variability of some modes.Comment: 7 pages (in A&A style), 7 eps figures. Accepted for A&A Main Journa
The effects of booster sessions on self-management interventions for chronic musculoskeletal pain: a systematic review and meta-analysis of randomised controlled trials
Our objective was to investigate the effectiveness of booster sessions after self-management interventions as a means of maintaining self-management behaviours in the treatment of chronic musculoskeletal pain. We searched MEDLINE, EMBASE, Science Citation Index, Cochrane Central Register of Controlled Trials and PsycINFO. Two authors independently identified eligible trials and collected data. We calculated the odds ratio (OR) for the analyses of dichotomous data, and standardised mean differences (SMD) with 95% confidence interval (CI) for continuous variables. Our search identified 14 studies with a total of 1695 patients. All studies were at high risk of bias and provided very low quality evidence. For the primary outcomes, booster sessions had no evidence of an effect on improving patient-reported outcomes on physical function (SMD-0.13, 95%CI -0.32 to -0.06; P=0.18), pain-related disability (SMD-0.16, 95%CI -0.36 to 0.03; P=0.11) and pain self-efficacy (SMD 0.15, 95%CI -0.07 to 0.36; P=0.18). For the secondary outcomes, booster sessions caused a significant reduction in patient-reported pain catastrophising (SMD-0.42, 95%CI -0.64 to -0.19; P=0.0004), and no evidence of an effect on patient-reported pain intensity, depression, coping or treatment adherence. There is currently little evidence that booster sessions are an effective way to prolong positive treatment effects or improve symptoms of long-term musculoskeletal conditions following self-management interventions. However, the studies were few with high heterogeneity, high risk of bias and overall low quality of evidence. Our review argues against including booster sessions routinely to self-management interventions for the purpose of behaviour maintenance
Risk of fractures in half a million survivors of 20 cancers: a population-based matched cohort study using linked English electronic health records.
BACKGROUND: A history of multiple myeloma, prostate cancer, and breast cancer has been associated with adverse bone health, but associations across a broader range of cancers are unclear. We aimed to compare the risk of any bone fracture and major osteoporotic fractures in survivors of a wide range of cancers versus cancer-free individuals. METHODS: In this population-based matched cohort study, we used electronic health records from the UK Clinical Practice Research Datalink linked to hospital data. We included adults (aged ≥18 years) eligible for linkage, and we restricted the study start to Jan 2, 1998, onwards and applied administrative censoring on Jan 31, 2020. The cancer survivor group included survivors of the 20 most common cancers. Each individual with cancer was matched (age, sex, and general practice) to up to five controls (1:5) who were cancer-free. The primary outcomes were any bone fracture and any major osteoporotic fracture (pelvic, hip, wrist, spine, or proximal humeral fractures) occurring more than 1 year after index date (ie, the diagnosis date of the matched individual with cancer). We used Cox regression models, adjusted for shared risk factors, to estimate associations between cancer survivorship and bone fractures. FINDINGS: 578 160 adults with cancer diagnosed in 1998-2020 were matched to 3 226 404 cancer-free individuals. Crude incidence rates of fractures in cancer survivors ranged between 8·39 cases (95% CI 7·45-9·46) per 1000 person-years for thyroid cancer and 21·62 cases (20·18-23·18) per 1000 person-years for multiple myeloma. Compared with cancer-free individuals, the risk of any bone fracture was increased in 15 of 20 cancers, and of major osteoporotic fractures in 17 of 20 cancers. Effect sizes varied: adjusted hazard ratios (HRs) were largest for multiple myeloma (1·94, 95% CI 1·77-2·13) and prostate cancer (1·43, 1·39-1·47); HRs in the range 1·20-1·50 were seen for stomach, liver, pancreas, lung, breast, kidney, and CNS cancers; smaller associations (HR <1·20) were observed for malignant melanoma, non-Hodgkin lymphoma, leukaemia, and oesophageal, colorectal, and cervical cancers. Increased risks of major osteoporotic fracture were noted most substantially in multiple myeloma (2·25, 1·96-2·58) and CNS (2·12, 1·56-2·87), liver (1·62, 1·01-2·61), prostate (1·60, 1·53-1·67), and lung cancers (1·60, 1·44-1·77). Effect sizes tended to reduce over time since diagnosis but remained elevated for more than 5 years in several cancers, such as multiple myeloma and stomach, lung, breast, prostate, and CNS cancers. INTERPRETATION: Survivors of most types of cancer were at increased risk of bone fracture for several years after cancer, with variation by cancer type. These findings can help to inform mitigation and prevention strategies. FUNDING: Wellcome Trust
Investigating the properties of granulation in the red giants observed by Kepler
More than 1000 red giants have been observed by NASA/Kepler mission during a
nearly continuous period of ~ 13 months. The resulting high-frequency
resolution (< 0.03 muHz) allows us to study the granulation parameters of these
stars. The granulation pattern results from the convection motions leading to
upward flows of hot plasma and downward flows of cooler plasma. We fitted
Harvey-like functions to the power spectra, to retrieve the timescale and
amplitude of granulation. We show that there is an anti-correlation between
both of these parameters and the position of maximum power of acoustic modes,
while we also find a correlation with the radius, which agrees with the theory.
We finally compare our results with 3D models of the convection.Comment: 4 pages, 1 figure. To appear in the ASP proceedings of "The 61st
Fujihara seminar: Progress in solar/stellar physics with helio- and
asteroseismology", 13th-17th March 2011, Hakone, Japa
Asteroseismology and interferometry of the red giant star epsilon Oph
The GIII red giant star epsilon Oph has been found to exhibit several modes
of oscillation by the MOST mission. We interpret the observed frequencies of
oscillation in terms of theoretical radial p-mode frequencies of stellar
models. Evolutionary models of this star, in both shell H-burning and core
He-burning phases of evolution, are constructed using as constraints a
combination of measurements from classical ground-based observations (for
luminosity, temperature, and chemical composition) and seismic observations
from MOST. Radial frequencies of models in either evolutionary phase can
reproduce the observed frequency spectrum of epsilon Oph almost equally well.
The best-fit models indicate a mass in the range of 1.85 +/- 0.05 Msun with
radius of 10.55 +/- 0.15 Rsun. We also obtain an independent estimate of the
radius of epsilon Oph using high accuracy interferometric observations in the
infrared K' band, using the CHARA/FLUOR instrument. The measured limb darkened
disk angular diameter of epsilon Oph is 2.961 +/- 0.007 mas. Together with the
Hipparcos parallax, this translates into a photospheric radius of 10.39 +/-
0.07 Rsun. The radius obtained from the asteroseismic analysis matches the
interferometric value quite closely even though the radius was not constrained
during the modelling.Comment: 11 pages, accepted for publication in Astronomy & Astrophysic
Kepler White Paper: Asteroseismology of Solar-Like Oscillators in a 2-Wheel Mission
We comment on the potential for continuing asteroseismology of solar-type and
red-giant stars in a 2-wheel Kepler Mission. Our main conclusion is that by
targeting stars in the ecliptic it should be possible to perform high-quality
asteroseismology, as long as favorable scenarios for 2-wheel pointing
performance are met. Targeting the ecliptic would potentially facilitate unique
science that was not possible in the nominal Mission, notably from the study of
clusters that are significantly brighter than those in the Kepler field. Our
conclusions are based on predictions of 2-wheel observations made by a space
photometry simulator, with information provided by the Kepler Project used as
input to describe the degraded pointing scenarios. We find that elevated levels
of frequency-dependent noise, consistent with the above scenarios, would have a
significant negative impact on our ability to continue asteroseismic studies of
solar-like oscillators in the Kepler field. However, the situation may be much
more optimistic for observations in the ecliptic, provided that pointing resets
of the spacecraft during regular desaturations of the two functioning reaction
wheels are accurate at the < 1 arcsec level. This would make it possible to
apply a post-hoc analysis that would recover most of the lost photometric
precision. Without this post-hoc correction---and the accurate re-pointing it
requires---the performance would probably be as poor as in the Kepler-field
case. Critical to our conclusions for both fields is the assumed level of
pointing noise (in the short-term jitter and the longer-term drift). We suggest
that further tests will be needed to clarify our results once more detail and
data on the expected pointing performance becomes available, and we offer our
assistance in this work.Comment: NASA Kepler Mission White Paper; 10 pages, 2 figure
Polaris the Cepheid returns: 4.5 years of monitoring from ground and space
We present the analysis of 4.5 years of nearly continuous observations of the
classical Cepheid Polaris, which comprise the most precise data available for
this star. We have made spectroscopic measurements from ground and photometric
measurements from the WIRE star tracker and the SMEI instrument on the Coriolis
satellite. Measurements of the amplitude of the dominant oscillation (P = 4
days), that go back more than a century, show a decrease from 120 mmag to 30
mmag (V magnitude) around the turn of the millennium. It has been speculated
that the reason for the decrease in amplitude is the evolution of Polaris
towards the edge of the instability strip. However, our new data reveal an
increase in the amplitude by about 30% from 2003-2006. It now appears that the
amplitude change is cyclic rather than monotonic, and most likely the result of
a pulsation phenomenon. In addition, previous radial velocity campaigns have
claimed the detection of long-period variation in Polaris (P > 40 days). Our
radial velocity data are more precise than previous datasets, and we find no
evidence for additional variation for periods in the range 3-50 days with an
upper limit of 100 m/s. However, in the WIRE data we find evidence of variation
on time-scales of 2-6 days, which we interpret as being due to granulation.Comment: Accepted by ApJ. 8 pages. Quality of figures 1+3+7 degrade
The discovery of WASP-151b, WASP-153b, WASP-156b: Insights on giant planet migration and the upper boundary of the Neptunian desert
To investigate the origin of the features discovered in the exoplanet population, the knowledge of exoplanets’ mass and radius with a good precision (≲10%) is essential. To achieve this purpose the discovery of transiting exoplanets around bright stars is of prime interest. In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15%. WASP-151b and WASP-153b are two hot Saturns with masses, radii, densities and equilibrium temperatures of 0.31−0.03+0.04 MJ, 1.13−0.03+0.03 RJ, 0.22−0.02+0.03 ρJ and 1290−10+20 K, and 0.39−0.02+0.02 MJ, 1.55−0.08+0.10 RJ, 0.11−0.02+0.02 ρJ and 1700−40+40 K, respectively. Their host stars are early G type stars (with mag V ~ 13) and their orbital periods are 4.53 and 3.33 days, respectively. WASP-156b is a super-Neptune orbiting a K type star (mag V = 11.6). It has a mass of 0.128−0.009+0.010 MJ, a radius of 0.51−0.02+0.02 RJ, a density of 1.0−0.1+0.1 ρJ, an equilibrium temperature of 970−20+30 K and an orbital period of 3.83 days. The radius of WASP-151b appears to be only slightly inflated, while WASP-153b presents a significant radius anomaly compared to a recently published model. WASP-156b, being one of the few well characterized super-Neptunes, will help to constrain the still debated formation of Neptune size planets and the transition between gas and ice giants. The estimates of the age of these three stars confirms an already observed tendency for some stars to have gyrochronological ages significantly lower than their isochronal ages. We propose that high eccentricity migration could partially explain this behavior for stars hosting a short period planet. Finally, these three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert. Their characteristics support that the ultra-violet irradiation plays an important role in this depletion of planets observed in the exoplanet population
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