8,969 research outputs found
Shear-induced anisotropic decay of correlations in hard-sphere colloidal glasses
Spatial correlations of microscopic fluctuations are investigated via
real-space experiments and computer simulations of colloidal glasses under
steady shear. It is shown that while the distribution of one-particle
fluctuations is always isotropic regardless of the relative importance of shear
as compared to thermal fluctuations, their spatial correlations show a marked
sensitivity to the competition between shear-induced and thermally activated
relaxation. Correlations are isotropic in the thermally dominated regime, but
develop strong anisotropy as shear dominates the dynamics of microscopic
fluctuations. We discuss the relevance of this observation for a better
understanding of flow heterogeneity in sheared amorphous solids.Comment: 6 pages, 4 figure
Additional outcomes and subgroup analyses of NXY-059 for acute ischemic stroke in the SAINT I trial
<p><b>Background and Purpose:</b> NXY-059 is a free radical-trapping neuroprotectant demonstrated to reduce disability from ischemic stroke. We conducted analyses on additional end points and sensitivity analyses to confirm our findings.</p>
<p><b>Methods:</b> We randomized 1722 patients with acute ischemic stroke to a 72-hour infusion of placebo or intravenous NXY-059 within 6 hours of stroke onset. The primary outcome was disability at 90 days, as measured by the modified Rankin Scale (mRS), a 6-point scale ranging from 0 (no residual symptoms) to 5 (bed-bound, requiring constant care). Additional and exploratory analyses included mRS at 7 and 30 days; subgroup interactions with final mRS; assessments of activities of daily living by Barthel index; and National Institutes of Health Stroke Scale (NIHSS) neurological scores at 7 and 90 days.</p>
<p><b>Results:</b> NXY-059 significantly improved the distribution of the mRS disability score compared with placebo at 7, 30, and 90 days (Cochran-Mantel-Haenszel test P=0.002, 0.004, 0.038, respectively; 90-day common odds ratio 1.20; 95% CI, 1.01 to 1.42). The benefit was not attributable to any specific baseline characteristic, stratification variable or subgroup interaction. Neurological scores were improved at 7 days (odds ratio [OR], 1.46; 95% CI, 1.13, 1.89; P=0.003) and the Barthel index was improved at 7 and 30 days (OR, 1.55; 95% CI, 1.22, 1.98; P<0.0001; OR, 1.27; 95% CI, 1.01, 1.59; P=0.02).</p>
<p><b>Conclusions:</b> NXY-059 within 6 hours of acute ischemic stroke significantly reduced disability. Benefit on neurological scores and activities of daily living was detectable early but not significant at 90 days; however, our trial was underpowered to measure effects on the neurological examination. The benefit on disability is not confounded by interactions and is supported by other outcome measures.</p>
Transport Far From Equilibrium --- Uniform Shear Flow
The BGK model kinetic equation is applied to spatially inhomogeneous states
near steady uniform shear flow. The shear rate of the reference steady state
can be large so the states considered include those very far from equilibrium.
The single particle distribution function is calculated exactly to first order
in the deviations of the hydrodynamic field gradients from their values in the
reference state. The corresponding non-linear hydrodynamic equaitons are
obtained and the set of transport coefficients are identified as explicit
functions of the shear rate. The spectrum of the linear hydrodynamic equation
is studied in detail and qualitative differences from the spectrum for
equilibrium fluctuations are discussed. Conditions for instabilities at long
wavelengths are identified and disccused.Comment: 32 pages, 1 figure, RevTeX, submitted to Phys. Rev.
Deforming the Maxwell-Sim Algebra
The Maxwell alegbra is a non-central extension of the Poincar\'e algebra, in
which the momentum generators no longer commute, but satisfy
. The charges commute with the momenta,
and transform tensorially under the action of the angular momentum generators.
If one constructs an action for a massive particle, invariant under these
symmetries, one finds that it satisfies the equations of motion of a charged
particle interacting with a constant electromagnetic field via the Lorentz
force. In this paper, we explore the analogous constructions where one starts
instead with the ISim subalgebra of Poincar\'e, this being the symmetry algebra
of Very Special Relativity. It admits an analogous non-central extension, and
we find that a particle action invariant under this Maxwell-Sim algebra again
describes a particle subject to the ordinary Lorentz force. One can also deform
the ISim algebra to DISim, where is a non-trivial dimensionless
parameter. We find that the motion described by an action invariant under the
corresponding Maxwell-DISim algebra is that of a particle interacting via a
Finslerian modification of the Lorentz force.Comment: Appendix on Lifshitz and Schrodinger algebras adde
Low body mass not vitamin D receptor polymorphisms predict osteoporosis in patients with inflammatory bowel disease
Stability of Uniform Shear Flow
The stability of idealized shear flow at long wavelengths is studied in
detail. A hydrodynamic analysis at the level of the Navier-Stokes equation for
small shear rates is given to identify the origin and universality of an
instability at any finite shear rate for sufficiently long wavelength
perturbations. The analysis is extended to larger shear rates using a low
density model kinetic equation. Direct Monte Carlo Simulation of this equation
is computed with a hydrodynamic description including non Newtonian rheological
effects. The hydrodynamic description of the instability is in good agreement
with the direct Monte Carlo simulation for , where is the mean
free time. Longer time simulations up to are used to identify the
asymptotic state as a spatially non-uniform quasi-stationary state. Finally,
preliminary results from molecular dynamics simulation showing the instability
are presented and discussed.Comment: 25 pages, 9 figures (Fig.8 is available on request) RevTeX, submitted
to Phys. Rev.
World small animal veterinary association renal pathology initiative: classification of glomerular diseases in dogs
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