3,427 research outputs found
Incidence and costs of unintentional falls in older people in the United Kingdom
STUDY OBJECTIVE: To estimate the number of accident and emergency (A&E) attendances, admissions to hospital, and the associated costs as a result of unintentional falls in older people. DESIGN: Analysis of national databases for cost of illness. SETTING: United Kingdom, 1999, cost to the National Health Service (NHS) and Personal Social Services (PSS). PARTICIPANTS: Four age groups of people 60 years and over (60–64, 65–69, 70–74, and 75) attending an A&E department or admitted to hospital after an unintentional fall. Databases analysed were the Home Accident Surveillance System (HASS) and Leisure Accident Surveillance System (LASS), and Hospital Episode Statistics (HES). MAIN RESULTS: There were 647 721 A&E attendances and 204 424 admissions to hospital for fall related injuries in people aged 60 years and over. For the four age groups A&E attendance rates per 10 000 population were 273.5, 287.3, 367.9, and 945.3, and hospital admission rates per 10 000 population were 34.5, 52.0, 91.9, and 368.6. The cost per 10 000 population was £300 000 in the 60–64 age group, increasing to £1 500 000 in the 75 age group. These falls cost the UK government £981 million, of which the NHS incurred 59.2%. Most of the costs (66%) were attributable to falls in those aged 75 years. The major cost driver was inpatient admissions, accounting for 49.4% of total cost of falls. Long term care costs were the second highest, accounting for 41%, primarily in those aged 75 years. CONCLUSIONS: Unintentional falls impose a substantial burden on health and social services
The Octave (Birmingham - Sheffield Hallam) automated pipeline for extracting oscillation parameters of solar-like main-sequence stars
The number of main-sequence stars for which we can observe solar-like
oscillations is expected to increase considerably with the short-cadence
high-precision photometric observations from the NASA Kepler satellite. Because
of this increase in number of stars, automated tools are needed to analyse
these data in a reasonable amount of time. In the framework of the asteroFLAG
consortium, we present an automated pipeline which extracts frequencies and
other parameters of solar-like oscillations in main-sequence and subgiant
stars. The pipeline uses only the timeseries data as input and does not require
any other input information. Tests on 353 artificial stars reveal that we can
obtain accurate frequencies and oscillation parameters for about three quarters
of the stars. We conclude that our methods are well suited for the analysis of
main-sequence stars, which show mainly p-mode oscillations.Comment: accepted by MNRA
Tests of the asymptotic large frequency separation of acoustic oscillations in solar-type and red giant stars
Asteroseismology, i.e. the study of the internal structures of stars via
their global oscillations, is a valuable tool to obtain stellar parameters such
as mass, radius, surface gravity and mean density. These parameters can be
obtained using certain scaling relations which are based on an asymptotic
approximation. Usually the observed oscillation parameters are assumed to
follow these scaling relations. Recently, it has been questioned whether this
is a valid approach, i.e., whether the order of the observed oscillation modes
are high enough to be approximated with an asymptotic theory. In this work we
use stellar models to investigate whether the differences between observable
oscillation parameters and their asymptotic estimates are indeed significant.
We compute the asymptotic values directly from the stellar models and derive
the observable values from adiabatic pulsation calculations of the same models.
We find that the extent to which the atmosphere is included in the models is a
key parameter. Considering a larger extension of the atmosphere beyond the
photosphere reduces the difference between the asymptotic and observable values
of the large frequency separation. Therefore, we conclude that the currently
suggested discrepancies in the scaling relations might have been overestimated.
Hence, based on the results presented here we believe that the suggestions of
Mosser et al. (2013) should not be followed without careful consideration.Comment: 6 pages, 4 figures, 1 table, accepted for publication by MNRAS as a
Letter to the Edito
BiSON data preparation: A correction for differential extinction and the weighted averaging of contemporaneous data
The Birmingham Solar Oscillations Network (BiSON) has provided high-quality
high-cadence observations from as far back in time as 1978. These data must be
calibrated from the raw observations into radial velocity and the quality of
the calibration has a large impact on the signal-to-noise ratio of the final
time series. The aim of this work is to maximise the potential science that can
be performed with the BiSON data set by optimising the calibration procedure.
To achieve better levels of signal-to-noise ratio we perform two key steps in
the calibration process: we attempt a correction for terrestrial atmospheric
differential extinction; and the resulting improvement in the calibration
allows us to perform weighted averaging of contemporaneous data from different
BiSON stations. The improvements listed produce significant improvement in the
signal-to-noise ratio of the BiSON frequency-power spectrum across all
frequency ranges. The reduction of noise in the power spectrum will allow
future work to provide greater constraint on changes in the oscillation
spectrum with solar activity. In addition, the analysis of the low-frequency
region suggests we have achieved a noise level that may allow us to improve
estimates of the upper limit of g-mode amplitudes.Comment: Accepted for publication in MNRAS; 10 pages, 7 figure
The relation between and for solar-like oscillations
Establishing relations between global stellar parameters and asteroseismic
quantities can help improve our understanding of stellar astrophysics and
facilitate the interpretation of observations. We present an observed relation
between the large frequency separation, , and the frequency of
maximum power, . We find that is proportional to
, allowing prediction of to about 15 per cent
given . Our result is further supported by established scaling
relations for and and by extended stellar model
calculations, which confirm that can be estimated using this
relation for basically any star showing solar-like oscillations in the
investigated range (0.5<M/Msol<4.0).Comment: 5 pages, 8 figures, Letter accepted by MNRA
Changing the Scaling Relation: The Need For a Mean Molecular Weight Term
The scaling relations that relate the average asteroseismic parameters
and to the global properties of stars are used quite
extensively to determine stellar properties. While the scaling
relation has been examined carefully and the deviations from the relation have
been well documented, the scaling relation has not been examined
as extensively. In this paper we examine the scaling relation
using a set of stellar models constructed to have a wide range of mass,
metallicity, and age. We find that as with , does not
follow the simple scaling relation. The most visible deviation is because of a
mean molecular weight term and a term that are commonly ignored. The
remaining deviation is more difficult to address. We find that the influence of
the scaling relation errors on asteroseismically derived values of are
well within uncertainties. The influence of the errors on mass and radius
estimates is small for main sequence and subgiants, but can be quite large for
red giants.Comment: 15 pages, 14 figures, accepted for publication in Ap
Sounding stellar cycles with Kepler - I. Strategy for selecting targets
The long-term monitoring and high photometric precision of the Kepler
satellite will provide a unique opportunity to sound the stellar cycles of many
solar-type stars using asteroseismology. This can be achieved by studying
periodic changes in the amplitudes and frequencies of the oscillation modes
observed in these stars. By comparing these measurements with conventional
ground-based chromospheric activity indices, we can improve our understanding
of the relationship between chromospheric changes and those taking place deep
in the interior throughout the stellar activity cycle. In addition,
asteroseismic measurements of the convection zone depth and differential
rotation may help us determine whether stellar cycles are driven at the top or
at the base of the convection zone. In this paper, we analyze the precision
that will be possible using Kepler to measure stellar cycles, convection zone
depths, and differential rotation. Based on this analysis, we describe a
strategy for selecting specific targets to be observed by the Kepler
Asteroseismic Investigation for the full length of the mission, to optimize
their suitability for probing stellar cycles in a wide variety of solar-type
stars.Comment: accepted for publication in MNRA
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