66,472 research outputs found
The effects of a 12-week leisure centre-based, group exercise intervention for people moderately affected with multiple sclerosis: a randomized controlled pilot study
<b>Objective:</b> To establish the effects of a 12-week, community-based group exercise intervention for people moderately affected with multiple sclerosis.
<b>Design:</b> Randomised controlled pilot trial.
<b>Setting:</b> Two community leisure centres.
<b>Participants:</b> Thirty-two participants with multiple sclerosis randomised into intervention or control groups.
<b>Intervention:</b> The intervention group received 12 weeks of twice weekly, 60-minute group exercise sessions, including mobility, balance and resistance exercises. The control group received usual care.
<b>Main outcome measures:</b> An assessor blinded to group allocation assessed participants at baseline, after eight weeks and after 12 weeks. The primary outcome measure was 25-foot (7.6 m) walk time, secondary outcomes assessed walking endurance, balance, physical function, leg strength, body mass index, activity levels, fatigue, anxiety and depression, quality of life and goal attainment.
<b>Results:</b> The intervention made no statistically significant difference to the results of participantsâ 25-foot walk time. However the intervention led to many improvements. In the intervention group levels of physical activity improved statistically between baseline and week 8 (P < 0.001) and baseline and week 12 (P = 0.005). Balance confidence results showed a significant difference between baseline and week 12 (P = 0.013). Good effect sizes were found for dynamic balance (d = 0.80), leg strength (d = 1.33), activity levels (d = 1.05) and perceived balance (d = 0.94).
<b>Conclusion:</b> The results of the study suggest that community-based group exercise classes are a feasible option for people moderately affected with multiple sclerosis, and offer benefits such as improved physical activity levels, balance and leg strength
Geothermal systems simulation: A case study
Geothermal reservoir simulation is a key step for developing sustainable and efficient strategies for the exploitation of geothermal resources. It is applied in the assessment of several areas of reservoir engineering, such as reservoir performance and re-injection programs, pressure decline in depletion, phase transition conditions, and natural evolution of hydrothermal convection systems. Fluid flow and heat transfer in rock masses, fluid-rock chemical interaction and rock mass deformation are some of the processes addressed in reservoir modelling. The case study of the Las Tres Virgenes (LTV) geothermal field (10 MWe), Baja California Sur, Mexico is presented. Three dimensional (3D) natural state simulations were carried out from emplacement and cooling of two spherical magma chambers using a conductive approach. A conceptual model of the volcanic system was developed on a lithostratigraphic and geochronological basis. Magma chamber volumes were established from eruptive volumes estimations. The thermophysical properties of the medium were assumed to correspond to the dominant rock in each lithological unit as an initial value, and further calibration was made considering histograms of experimentally obtained thermophysical properties of rocks. As the boundaries of the model lie far from the thermal anomaly, we assumed specified temperature boundaries. A Finite Volume (FV) numerical scheme was implemented in a Fortran 90 code to solve the heat equation. Static formation temperatures from well logs were used for validation of the numerical results. Good agreement was observed in those geothermal wells dominated by conductive heat transfer. For other wells, however, it is clear that conduction alone cannot explain observed behaviour, three-dimensional convective models are being implemented for future multiphysics simulations
The refractive index and wave vector in passive or active media
Materials that exhibit loss or gain have a complex valued refractive index
. Nevertheless, when considering the propagation of optical pulses, using a
complex is generally inconvenient -- hence the standard choice of
real-valued refractive index, i.e. n_s = \RealPart (\sqrt{n^2}). However, an
analysis of pulse propagation based on the second order wave equation shows
that use of results in a wave vector \emph{different} to that actually
exhibited by the propagating pulse. In contrast, an alternative definition n_c
= \sqrt{\RealPart (n^2)}, always correctly provides the wave vector of the
pulse. Although for small loss the difference between the two is negligible, in
other cases it is significant; it follows that phase and group velocities are
also altered. This result has implications for the description of pulse
propagation in near resonant situations, such as those typical of metamaterials
with negative (or otherwise exotic) refractive indices.Comment: Phys. Rev. A, to appear (2009
SEQUENTIAL REGRESSION: A FLEXIBLE TOOL FOR TIME SERIES MODELING
Research Methods/ Statistical Methods,
Universal aging properties at a disordered critical point
We investigate, analytically near the dimension and numerically in
, the non equilibrium relaxational dynamics of the randomly diluted Ising
model at criticality. Using the Exact Renormalization Group Method to one loop,
we compute the two times correlation function and Fluctuation
Dissipation Ratio (FDR) for any Fourier mode of the order parameter, of finite
wave vector . In the large time separation limit, the FDR is found to reach
a non trivial value independently of (small) and coincide with
the FDR associated to the the {\it total} magnetization obtained previously.
Explicit calculations in real space show that the FDR associated to the {\it
local} magnetization converges, in the asymptotic limit, to this same value
. Through a Monte Carlo simulation, we compute the autocorrelation
function in three dimensions, for different values of the dilution fraction
at . Taking properly into account the corrections to scaling, we find,
according to the Renormalization Group predictions, that the autocorrelation
exponent is independent on . The analysis is complemented by a
study of the non equilibrium critical dynamics following a quench from a
completely ordered state.Comment: 8 pages, 5 figure
New challenges for public debt in advanced economies Summary of the conference held in Strasbourg on 16-17 September 2010.
On 16-17 September 2010, the Banque de Franceâs Directorate General Economics and International Relations and the Bureau dâĂ©conomie thĂ©orique et appliquĂ©e (BETA) of Strasbourg University jointly hosted a conference on the topic âNew challenges for public debt in advanced economiesâ that brought together 70 economists from French and foreign universities, ESCB and other central banks, and European and international institutions.public debt, governance, financial markets, fiscal policy.
Effect of proton irradiation on the normal state low-energy excitations of Ba(FeRh)As superconductors
We present a \asnmr Nuclear Magnetic Resonance (NMR) and resistivity study of
the effect of 5.5 MeV proton irradiation on the optimal electron doped (
0.068) and overdoped ( 0.107) Ba(FeRh)As iron based
superconductors. While the proton induced defects only mildly suppress the
critical temperature and increase residual resistivity in both compositions,
sizable broadening of the NMR spectra was observed in all the irradiated
samples at low temperature. The effect is significantly stronger in the
optimally doped sample where the Curie Weiss temperature dependence of the line
width suggests the onset of ferromagnetic correlations coexisting with
superconductivity at the nanoscale. 1/T measurements revealed that the
energy barrier characterizing the low energy spin fluctuations of these
compounds is enhanced upon proton irradiation, suggesting that the defects are
likely slowing down the fluctuations between ( and (,0) nematic
ground states.Comment: 9 pages, 9 figure
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