957 research outputs found
Joint disease mapping using six cancers in the Yorkshire region of England
OBJECTIVES:
The aims of this study were to model jointly the incidence rates of six smoking related cancers in the Yorkshire region of England, to explore the patterns of spatial correlation amongst them, and to estimate the relative weight of smoking and other shared risk factors for the relevant disease sites, both before and after adjustment for socioeconomic background (SEB).
METHODS:
Data on the incidence of oesophagus, stomach, pancreas, lung, kidney, and bladder cancers between 1983 and 2003 were extracted from the Northern & Yorkshire Cancer Registry database for the 532 electoral wards in the Yorkshire region. Using postcode of residence, each case was assigned an area-based measure of SEB using the Townsend index. Standardised incidence ratios (SIRs) were calculated for each cancer site and their correlations investigated. The joint analysis of the spatial variation in incidence used a Bayesian shared-component model. Three components were included to represent differences in smoking (for all six sites), bodyweight/obesity (for oesophagus, pancreas and kidney cancers) and diet/alcohol consumption (for oesophagus and stomach cancers).
RESULTS:
The incidence of cancers of the oesophagus, pancreas, kidney, and bladder was relatively evenly distributed across the region. The incidence of stomach and lung cancers was more clustered around the urban areas in the south of the region, and these two cancers were significantly associated with higher levels of area deprivation. The incidence of lung cancer was most impacted by adjustment for SEB, with the rural/urban split becoming less apparent. The component representing smoking had a larger effect on cancer incidence in the eastern part of the region. The effects of the other two components were small and disappeared after adjustment for SEB.
CONCLUSIONS:
This study demonstrates the feasibility of joint disease modelling using data from six cancer sites. Incidence estimates are more precise than those obtained without smoothing. This methodology may be an important tool to help authorities evaluate healthcare system performance and the impact of policies
High definition tDCS effect on postural control in healthy individuals: Entropy analysis of a crossover clinical trial
Objective: Converging evidence supporting an effect of transcranial direct current stimulation (tDCS) on postural control and human verticality perception highlights this strategy as promising for post-stroke rehabilitation. We have previously demonstrated polarity-dependent effects of high-definition tDCS (HD-tDCS) on weight-bearing asymmetry. However, there is no investigation regarding the time-course of effects on postural control induced by HD-tDCS protocols. Thus, we performed a nonlinear time series analysis focusing on the entropy of the ground reaction force as a secondary investigation of our randomized, double-blind, placebo-controlled, crossover clinical trial. Materials and Methods: Twenty healthy right-handed young adults received the following conditions (random order, separate days); anode center HD-tDCS, cathode center HD-tDCS or sham HD-tDCS at 1, 2, and 3 mA over the right temporo-parietal junction (TPJ). Using summarized time series of transfer entropy, we evaluated the exchanging information (causal direction) between both force plates and compared the dose-response across the healthy subjects with a Generalized Linear Hierarchical/Mixed Model (GLMM). Results: We found significant variation during the dynamic information flow (p \u3c 0.001) among the dominant bodyside (and across time). A greater force transfer entropy was observed from the right to the left side during the cathode-center HD-tDCS up to 2 mA, with a causal relationship in the information flow (equilibrium force transfer) from right to left that decreased over time. Conclusions: HD-tDCS intervention induced a dynamic influence over time on postural control entropy. Right hemisphere TPJ stimulation using cathode-center HD-tDCS can induce an asymmetry of body weight distribution towards the ipsilateral side of stimulation. These results support the clinical potential of HD-tDCS for post-stroke rehabilitation
Comparative Study of full QCD Hadron Spectrum and Static Quark Potential with Improved Actions
We investigate effects of action improvement on the light hadron spectrum and
the static quark potential in two-flavor QCD for GeV and
. We compare a renormalization group improved action with
the plaquette action for gluons, and the SW-clover action with the Wilson
action for quarks. We find a significant improvement in the hadron spectrum by
improving the quark action, while the gluon improvement is crucial for a
rotationally invariant static potential. We also explore the region of light
quark masses corresponding to on a 2.7 fm lattice using
the improved gauge and quark action. A flattening of the potential is not
observed up to 2 fm.Comment: LaTeX, 35 pages, 22 eps figures, uses revtex and eps
Cluster Spin Glass Distribution Functions in LaSrCuO
Signatures of the cluster spin glass have been found in a variety of
experiments, with an effective onset temperature that is frequency
dependent. We reanalyze the experimental results and find that they are
characterized by a distribution of activation energies, with a nonzero glass
transition temperature . While the distribution of activation
energies is the same, the distribution of weights depends on the process.
Remarkably, the weights are essentially doping independent.Comment: 5 pages, 5 ps figure
Elementary excitations of trapped Bose gas in the large-gas-parameter regime
We study the effect of going beyond the Gross-Pitaevskii theory on the
frequencies of collective oscillations of a trapped Bose gas in the large gas
parameter regime. We go beyond the Gross-Pitaevskii regime by including a
higher-order term in the interatomic correlation energy. To calculate the
frequencies we employ the sum-rule approach of many-body response theory
coupled with a variational method for the determination of ground-state
properties. We show that going beyond the Gross-Pitaevskii approximation
introduces significant corrections to the collective frequencies of the
compressional mode.Comment: 17 pages with 4 figures. To be published in Phys. Rev.
Thermodynamics of SU(3) gauge theory on anisotropic lattices
Finite temperature SU(3) gauge theory is studied on anisotropic lattices
using the standard plaquette gauge action. The equation of state is calculated
on , and lattices with
the anisotropy , where and are the
spatial and temporal lattice spacings. Unlike the case of the isotropic lattice
on which data deviate significantly from the leading scaling behavior,
the pressure and energy density on an anisotropic lattice are found to satisfy
well the leading scaling from our coarsest lattice, . With
three data points at , 5 and 6, we perform a well controlled
continuum extrapolation of the equation of state. Our results in the continuum
limit agree with a previous result from isotropic lattices using the same
action, but have smaller and more reliable errors.Comment: RevTeX, 21 pages, 17 PS figures. A quantitative test about the
benefit of anisotropic lattices added, minor errors corrected. Final version
for PR
Atom loss and the formation of a molecular Bose-Einstein condensate by Feshbach resonance
In experiments conducted recently at MIT on Na Bose-Einstein condensates [S.
Inouye et al, Nature 392, 151 (1998); J. Stenger et al, Phys. Rev. Lett. 82,
2422 (1999)], large loss rates were observed when a time-varying magnetic field
was used to tune a molecular Feshbach resonance state near the state of a pair
of atoms in the condensate. A collisional deactivation mechanism affecting a
temporarily formed molecular condensate [see V. A. Yurovsky, A. Ben-Reuven, P.
S. Julienne and C. J. Williams, Phys. Rev. A 60, R765 (1999)], studied here in
more detail, accounts for the results of the slow-sweep experiments. A best fit
to the MIT data yields a rate coefficient for deactivating atom-molecule
collisions of 1.6e-10 cm**3/s. In the case of the fast sweep experiment, a
study is carried out of the combined effect of two competing mechanisms, the
three-atom (atom-molecule) or four-atom (molecule-molecule) collisional
deactivation vs. a process of two-atom trap-state excitation by curve crossing
[F. H. Mies, P. S. Julienne, and E. Tiesinga, Phys. Rev. A 61, 022721 (2000)].
It is shown that both mechanisms contribute to the loss comparably and
nonadditively.Comment: LaTeX, 14 pages, 12 PostScript figures, uses REVTeX and psfig,
submitted to Physical Review
The Magnetic Field of the Solar Corona from Pulsar Observations
We present a novel experiment with the capacity to independently measure both
the electron density and the magnetic field of the solar corona. We achieve
this through measurement of the excess Faraday rotation due to propagation of
the polarised emission from a number of pulsars through the magnetic field of
the solar corona. This method yields independent measures of the integrated
electron density, via dispersion of the pulsed signal and the magnetic field,
via the amount of Faraday rotation. In principle this allows the determination
of the integrated magnetic field through the solar corona along many lines of
sight without any assumptions regarding the electron density distribution. We
present a detection of an increase in the rotation measure of the pulsar
J18012304 of approximately 160 \rad at an elongation of 0.95 from
the centre of the solar disk. This corresponds to a lower limit of the magnetic
field strength along this line of sight of . The lack of
precision in the integrated electron density measurement restricts this result
to a limit, but application of coronal plasma models can further constrain this
to approximately 20mG, along a path passing 2.5 solar radii from the solar
limb. Which is consistent with predictions obtained using extensions to the
Source Surface models published by Wilcox Solar ObservatoryComment: 16 pages, 4 figures (1 colour): Submitted to Solar Physic
Nucleon mass and sigma term from lattice QCD with two light fermion flavors
We analyze Nf=2 nucleon mass data with respect to their dependence on the
pion mass down to mpi = 157 MeV and compare it with predictions from covariant
baryon chiral perturbation theory (BChPT). A novel feature of our approach is
that we fit the nucleon mass data simultaneously with the directly obtained
pion-nucleon sigma-term. Our lattice data below mpi = 435 MeV is well described
by O(p^4) BChPT and we find sigma=37(8)(6) MeV for the sigma-term at the
physical point. Using the nucleon mass to set the scale we obtain a Sommer
parameter of r_0=0.501(10)(11) fm.Comment: 26 pages, 11 figures, 5 tables. Version to appear in NPB with a few
more details on the fit parameter
Lagrangian Becchi-Rouet-Stora-Tyutin treatment of collective coordinates
The Becchi-Rouet-Stora-Tyutin (BRST) treatment for the quantization of
collective coordinates is considered in the Lagrangian formalism. The motion of
a particle in a Riemannian manifold is studied in the case when the classical
solutions break a non-abelian global invariance of the action. Collective
coordinates are introduced, and the resulting gauge theory is quantized in the
BRST antifield formalism. The partition function is computed perturbatively to
two-loops, and it is shown that the results are independent of gauge-fixing
parameters.Comment: LaTeX file, 26 pages, PostScript figures at end of fil
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