6,708 research outputs found
Cost effectiveness of a community based exercise programme in over 65 year olds: cluster randomised trial
OBJECTIVE: To assess the cost effectiveness of a community based exercise programme as a population
wide public health intervention for older adults.
DESIGN: Pragmatic, cluster randomised community intervention trial.
Setting: 12 general practices in Sheffield; four randomly selected as intervention populations, and eight as
control populations.
PARTICIPANTS: All those aged 65 and over in the least active four fifths of the population responding to a
baseline survey. There were 2283 eligible participants from intervention practices and 4137 from control
practices.
INTERVENTION: Eligible subjects were invited to free locally held exercise classes, made available for two
years.
MAIN OUTCOME MEASURES: All cause and exercise related cause specific mortality and hospital service use
at two years, and health status assessed at baseline, one, and two years using the SF-36. A cost utility
analysis was also undertaken.
RESULTS: Twenty six per cent of the eligible intervention practice population attended one or more exercise
sessions. There were no significant differences in mortality rates, survival times, or admissions. After
adjusting for baseline characteristics, patients in intervention practices had a lower decline in health status,
although this reached significance only for the energy dimension and two composite scores (p,0.05). The
incremental average QALY gain of 0.011 per person in the intervention population resulted in an
incremental cost per QALY ratio of J17 174 (95% CI =J8300 to J87 120).
CONCLUSIONS: Despite a low level of adherence to the exercise programme, there were significant gains in
health related quality of life. The programme was more cost effective than many existing medical
interventions, and would be practical for primary care commissioning agencies to implement
Deceleration and Dispersion of Large-scale Coronal Bright Fronts
One of the most dramatic manifestations of solar activity are large-scale
coronal bright fronts (CBFs) observed in extreme ultraviolet (EUV) images of
the solar atmosphere. To date, the energetics and kinematics of CBFs remain
poorly understood, due to the low image cadence and sensitivity of previous EUV
imagers and the limited methods used to extract the features. In this paper,
the trajectory and morphology of CBFs was determined in order to investigate
the varying properties of a sample of CBFs, including their kinematics and
pulse shape, dispersion, and dissipation. We have developed a semi-automatic
intensity profiling technique to extract the morphology and accurate positions
of CBFs in 2.5-10 min cadence images from STEREO/EUVI. The technique was
applied to sequences of 171A and 195A images from STEREO/EUVI in order to
measure the wave properties of four separate CBF events. Following launch at
velocities of ~240-450kms^{-1} each of the four events studied showed
significant negative acceleration ranging from ~ -290 to -60ms^{-2}. The CBF
spatial and temporal widths were found to increase from ~50 Mm to ~200 Mm and
~100 s to ~1500 s respectively, suggesting that they are dispersive in nature.
The variation in position-angle averaged pulse-integrated intensity with
propagation shows no clear trend across the four events studied. These results
are most consistent with CBFs being dispersive magnetoacoustic waves.Comment: 15 pages, 18 figure
Opportunities for integrated pest management to control the poultry red mite, Dermanyssus gallinae
Dermanyssus gallinae is the most economically important ectoparasite of laying hens in Europe. Control of D. gallinae is already hampered by issues of pesticide resistance and product withdrawal and, with the prohibition of conventional cages in 2012 and the resulting switch to more structurally complex housing which favours red mite, the importance of managing this pest will increase. Integrated Pest Management (IPM), as often employed in agricultural pest control, may be a way to address these issues where a combination of different novel control methods could be used with/without conventional management techniques to provide a synergistic and more efficacious effect. Work at in our laboratory has shown that essential oils including thyme and garlic may act as effective D. gallinae repellents and acaricides, whilst preliminary vaccine studies have demonstrated a significant increase in mite mortality in vitro using concealed antigens. Work elsewhere 27 has considered predators and fungi for D. gallinae control and other husbandry techniques such as manipulating temperature and lighting regimes in poultry units. This paper will review the available and emerging techniques for D. gallinae control and discuss which techniques might be suitable for inclusion in an integrated management programme (e.g. synthetic acaricides and diatomaceous earths)
An experimental assessment of the effect of current on wave buoy measurements
This is the final version. Available on open access from Elsevier via the DOI in this recordWave measurement buoys provide characterisation of wave climates that forms the basis for the design of offshore systems. These buoys are commonly subjected to currents which affect the resulting wave measurements, and if not accounted for will result in errors in the estimated sea state parameters. The present work provides results and observations from experiments aimed at assessing the impact that currents have on wave buoy measurements, thereby informing processing techniques to more accurately include this effect. Through scaled testing (circa 1:15) in a combined wave–current test tank, buoy motions (diameter, D = 0.24m) are recorded in current only, waves only, and combined wave–current including oblique conditions. From these, the wave-induced motions are extracted and compared against three prediction methods based on established transfer function approaches as well as a frequency-domain hydrodynamic coefficient (HC) model based on potential flow. The scaled buoy was observed to have large, complex, irregular oscillatory vortex-induced motions (VIM) exceeding the buoy diameter. Both the magnitude and frequency of these oscillations was found to be significantly altered by the mooring stiffness and configuration whilst the addition of collinear waves was found not to affect the magnitude of VIM. Furthermore, due to the lack of VIM heave response and a large difference between the frequencies of the vortex-induced and wave induced horizontal motions, it was found that the VIM did not significantly alter the interpretation of the wave climate for the tested conditions. The HC model was found to accurately capture the observed modified hydrodynamics for opposing wave–current conditions, where larger horizontal motions than (typically) predicted are observed for all frequencies. This behaviour is concluded to result from increased excitation forces owing to the higher wavenumbers. The experiments highlight the potential effects of VIM on wave measurement performance of wave buoys, along with the complex and mooring-dependent nature of the response. Altered dynamics in the presence of currents are described which must be accounted for to avoid errors and the presented prediction methods provide a mechanism to account for these effects in wave processing methodologies which can subsequently reduce uncertainty in our understanding of the offshore environment.Engineering and Physical Sciences Research Council (EPSRC
Spotting the diffusion of New Psychoactive Substances over the Internet
Online availability and diffusion of New Psychoactive Substances (NPS)
represent an emerging threat to healthcare systems. In this work, we analyse
drugs forums, online shops, and Twitter. By mining the data from these sources,
it is possible to understand the dynamics of drugs diffusion and their
endorsement, as well as timely detecting new substances. We propose a set of
visual analytics tools to support analysts in tackling NPS spreading and
provide a better insight about drugs market and analysis
Statistical Physics of Irregular Low-Density Parity-Check Codes
Low-density parity-check codes with irregular constructions have been
recently shown to outperform the most advanced error-correcting codes to date.
In this paper we apply methods of statistical physics to study the typical
properties of simple irregular codes.
We use the replica method to find a phase transition which coincides with
Shannon's coding bound when appropriate parameters are chosen.
The decoding by belief propagation is also studied using statistical physics
arguments; the theoretical solutions obtained are in good agreement with
simulations. We compare the performance of irregular with that of regular codes
and discuss the factors that contribute to the improvement in performance.Comment: 20 pages, 9 figures, revised version submitted to JP
Irradiation of the secondary star in X-ray Nova Scorpii 1994 (=GRO J1655--40)
We have obtained intermediate resolution optical spectra of the black-hole
candidate Nova Sco 1994 in June 1996, when the source was in an X-ray/optical
active state (R~15.05). We measure the radial velocity curve of the secondary
star and obtain a semi-amplitude of 279+/-10 km/s; a value which is 30 per cent
larger than the value obtained when the source is in quiescence. Our large
value for K_2 is consistent with 60 +9,-7 per cent of the secondary star's
surface being heated; compared to 35 per cent, which is what one would expect
if only the inner face of the secondary star were irradiated. Effects such as
irradiation-induced flows on the secondary star may be important in explaining
the observed large value for K_2.Comment: 5 pages, 2 figures, accepted by MNRA
Error-correcting code on a cactus: a solvable model
An exact solution to a family of parity check error-correcting codes is
provided by mapping the problem onto a Husimi cactus. The solution obtained in
the thermodynamic limit recovers the replica symmetric theory results and
provides a very good approximation to finite systems of moderate size. The
probability propagation decoding algorithm emerges naturally from the analysis.
A phase transition between decoding success and failure phases is found to
coincide with an information-theoretic upper bound. The method is employed to
compare Gallager and MN codes.Comment: 7 pages, 3 figures, with minor correction
The mass of the neutron star in Cyg X-2 (V1341 Cyg)
Cygnus X-2 is one of the brightest and longest known X-ray sources. We
present high resolution optical spectroscopy of Cyg X-2 obtained over 4 years
which gives an improved mass function of 0.69 +/- 0.03 Msun (1 sigma error). In
addition, we resolve the rotationally broadened absorption features of the
secondary star for the first time, deriving a rotation speed of vsin(i) = 34.2
+/- 2.5 km per s (1 sigma error) which leads to a mass ratio of q = M_c/M_x =
0.34 +/- 0.04 (1 sigma error), assuming a tidally-locked and Roche lobe-filling
secondary). Hence with the lack of X-ray eclipses (i.e. i <~ 73 degrees) we can
set firm 95% confidence lower limits to the neutron star mass of M_x > 1.27
Msun and to the companion star mass of M_c > 0.39 Msun. However, by
additionally requiring that the companion must exceed 0.75 Msun (as required
theoretically to produce a steady low-mass X-ray binary), then M_x > 1.88 Msun
and i < 61 degrees (95% confidence lower and upper limit, respectively),
thereby making Cyg X-2 the highest mass neutron star measured to date. If
confirmed this would set significant constraints on the equation of state of
nuclear matter.Comment: 16 pages, 4 figures, ApJ Letters, accepted, LaTeX, aasms4.st
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