14,065 research outputs found
Can lay-led walking programmes increase physical activity in middle aged adults? : a randomised controlled trial
Study objective: To compare health walks, a community based lay-led walking scheme versus advice
only on physical activity and cardiovascular health status in middle aged adults.
Design: Randomised controlled trial with one year follow up. Physical activity was measured by questionnaire.
Other measures included attitudes to exercise, body mass index, cholesterol, aerobic capacity,
and blood pressure.
Setting: Primary care and community.
Participants: 260 men and women aged 40â70 years, taking less than 120 minutes of moderate
intensity activity per week.
Main results: Seventy three per cent of people completed the trial. Of these, the proportion increasing
their activity above 120 minutes of moderate intensity activity per week was 22.6% in the advice only
and 35.7% in the health walks group at 12 months (between group difference =13% (95% CI 0.003%
to 25.9%) p=0.05). Intention to treat analysis, using the last known value for missing cases,
demonstrated smaller differences between the groups (between group difference =6% (95% CI -5% to
16.4%)) with the trend in favour of health walks. There were improvements in the total time spent and
number of occasions of moderate intensity activity, and aerobic capacity, but no statistically significant
differences between the groups. Other cardiovascular risk factors remained unchanged.
Conclusions: There were no significant between group differences in self reported physical activity at
12 month follow up when the analysis was by intention to treat. In people who completed the trial,
health walks was more effective than giving advice only in increasing moderate intensity activity above
120 minutes per week
Speech and language difficulties in children with and without a family history of dyslexia
Comorbidity between SLI and dyslexia is well documented. Researchers have variously argued that dyslexia is a separate disorder from SLI, or that children with dyslexia show a subset of the difficulties shown in SLI. This study examines these hypotheses by assessing whether family history of dyslexia and speech and language difficulties are separable risk factors for literacy difficulties. Forty-six children with a family risk of dyslexia (FRD) and 36 children receiving speech therapy (SLT) were compared to 128 typically developing children. A substantial number (41.3%) of the children with FRD had received SLT. The nature of their difficulties did not differ in severity or form from those shown by the other children in SLT. However, both SLT and FRD were independent risk factors in predicting reading difficulties both concurrently and 6 months later. It is argued that the results are best explained in terms of Pennington's (2006) multiple deficits model
Elastic waves and transition to elastic turbulence in a two-dimensional viscoelastic Kolmogorov flow
We investigate the dynamics of the two-dimensional periodic Kolmogorov flow
of a viscoelastic fluid, described by the Oldroyd-B model, by means of direct
numerical simulations. Above a critical Weissenberg number the flow displays a
transition from stationary to randomly fluctuating states, via periodic ones.
The increasing complexity of the flow in both time and space at progressively
higher values of elasticity accompanies the establishment of mixing features.
The peculiar dynamical behavior observed in the simulations is found to be
related to the appearance of filamental propagating patterns, which develop
even in the limit of very small inertial non-linearities, thanks to the
feedback of elastic forces on the flow.Comment: 10 pages, 14 figure
XMM-Newton and INTEGRAL analysis of the Supergiant Fast X-ray Transient IGR J17354-3255
We present the results of combined INTEGRAL and XMM-Newton observations of
the supergiant fast X-ray transient (SFXT) IGR J173543255. Three XMM-Newton
observations of lengths 33.4 ks, 32.5 ks and 21.9 ks were undertaken, the first
an initial pointing to identify the correct source in the field of view and the
latter two performed around periastron. Simultaneous INTEGRAL observations
across of the orbital cycle were analysed but the source was neither
detected by IBIS/ISGRI nor by JEM-X. The XMM-Newton light curves display a
range of moderately bright X-ray activity but there are no particularly strong
flares or outbursts in any of the three observations. We show that the spectral
shape measured by XMM-Newton can be fitted by a consistent model throughout the
observation, suggesting that the observed flux variations are driven by
obscuration from a wind of varying density rather than changes in accretion
mode. The simultaneous INTEGRAL data rule out simple extrapolation of the
simple powerlaw model beyond the XMM-Newton energy range.Comment: 13 pages, 9 figures, This article has been accepted for publication
in Monthly Notices of the Royal Astronomical Society Published by Oxford
University Pres
Thermodiffusion in model nanofluids by molecular dynamics simulations
In this work, a new algorithm is proposed to compute single particle
(infinite dilution) thermodiffusion using Non-Equilibrium Molecular Dynamics
simulations through the estimation of the thermophoretic force that applies on
a solute particle. This scheme is shown to provide consistent results for
simple Lennard-Jones fluids and for model nanofluids (spherical non-metallic
nanoparticles + Lennard-Jones fluid) where it appears that thermodiffusion
amplitude, as well as thermal conductivity, decrease with nanoparticles
concentration. Then, in nanofluids in the liquid state, by changing the nature
of the nanoparticle (size, mass and internal stiffness) and of the solvent
(quality and viscosity) various trends are exhibited. In all cases the single
particle thermodiffusion is positive, i.e. the nanoparticle tends to migrate
toward the cold area. The single particle thermal diffusion 2 coefficient is
shown to be independent of the size of the nanoparticle (diameter of 0.8 to 4
nm), whereas it increases with the quality of the solvent and is inversely
proportional to the viscosity of the fluid. In addition, this coefficient is
shown to be independent of the mass of the nanoparticle and to increase with
the stiffness of the nanoparticle internal bonds. Besides, for these
configurations, the mass diffusion coefficient behavior appears to be
consistent with a Stokes-Einstein like law
Two-dimensional elastic turbulence
We investigate the effect of polymer additives on a two-dimensional
Kolmogorov flow at very low Reynolds numbers by direct numerical simulations of
the Oldroyd-B viscoelastic model. We find that above the elastic instability
threshold the flow develops the elastic turbulence regime recently observed in
experiments. We observe that both the turbulent drag and the Lyapunov exponent
increase with Weissenberg, indicating the presence of a disordered,
turbulent-like mixing flow. The energy spectrum develops a power-law scaling
range with an exponent close to the experimental and theoretical expectations
Cosmology with velocity dispersion counts: an alternative to measuring cluster halo masses
The evolution of galaxy cluster counts is a powerful probe of several
fundamental cosmological parameters. A number of recent studies using this
probe have claimed tension with the cosmology preferred by the analysis of the
Planck primary CMB data, in the sense that there are fewer clusters observed
than predicted based on the primary CMB cosmology. One possible resolution to
this problem is systematic errors in the absolute halo mass calibration in
cluster studies, which is required to convert the standard theoretical
prediction (the halo mass function) into counts as a function of the observable
(e.g., X-ray luminosity, Sunyaev-Zel'dovich flux, optical richness). Here we
propose an alternative strategy, which is to directly compare predicted and
observed cluster counts as a function of the one-dimensional velocity
dispersion of the cluster galaxies. We argue that the velocity dispersion of
groups/clusters can be theoretically predicted as robustly as mass but, unlike
mass, it can also be directly observed, thus circumventing the main systematic
bias in traditional cluster counts studies. With the aid of the BAHAMAS suite
of cosmological hydrodynamical simulations, we demonstrate the potential of the
velocity dispersion counts for discriminating even similar CDM models.
These predictions can be compared with the results from existing redshift
surveys such as the highly-complete Galaxy And Mass Assembly (GAMA) survey, and
upcoming wide-field spectroscopic surveys such as the Wide Area Vista
Extragalactic Survey (WAVES) and the Dark Energy Survey Instrument (DESI).Comment: 15 pages, 13 figures. Accepted for publication in MNRAS. New section
on cosmological forecasts adde
Criminal sentencing by preferred numbers
Criminal sentencing is a complex cognitive activity often performed by the unaided mind under suboptimal conditions. As such, sentencers may not behave according to policy, guidelines and training. We analyzed the distribution of sentences meted out in one year in two different jurisdictions (i.e., England and Wales, and New South Wales, Australia). We reveal that sentencers prefer certain numbers when meting out sentence lengths (in custody and community service) and amounts (for fines/compensation). These âcommon dosesâ accounted for over 90% of sentences in each jurisdiction. The size of these doses increased as sentences became more severe, and doses followed a logarithmic pattern. These findings are compatible with psychological research on preferred numbers and are reminiscent of Weberâs and Fechnerâs laws. Our findings run contrary to arguments against efforts to reduce judicial discretion, and potentially undermine the notion of individualized justice, as well as raise questions about the (cost) effectiveness of sentencing
New insights on accretion in Supergiant Fast X-ray Transients from XMM-Newton and INTEGRAL observations of IGR J175442619
XMM-Newton observations of the supergiant fast X-ray transient
IGRJ175442619 are reported and placed in the context of an analysis of
archival INTEGRAL/IBIS data that provides a refined estimate of the orbital
period at 4.92720.0004 days. A complete outburst history across the
INTEGRAL mission is reported. Although the new XMM-Newton observations (each
lasting 15 ks) targeted the peak flux in the phase-folded hard X-ray
light curve of IGRJ175442619, no bright outbursts were observed, the
source spending the majority of the exposure at intermediate luminosities of
the order of several 10ergs (0.510keV) and
displaying only low level flickering activity. For the final portion of the
exposure, the luminosity of IGRJ175442619 dropped to
410ergs (0.5 - 10 keV), comparable with the
lowest luminosities ever detected from this source, despite the observations
being taken near to periastron. We consider the possible orbital geometry of
IGRJ175442619 and the implications for the nature of the mass transfer
and accretion mechanisms for both IGRJ175442619 and the SFXT population.
We conclude that accretion under the `quasi-spherical accretion' model provides
a good description of the behaviour of IGRJ175442619, and suggest an
additional mechanism for generating outbursts based upon the mass accumulation
rate in the hot shell (atmosphere) that forms around the NS under the
quasi-spherical formulation. Hence we hope to aid in explaining the varied
outburst behaviours observed across the SFXT population with a consistent
underlying physical model.Comment: 12 pages, 5 figures, accepted for publication in MNRA
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