660 research outputs found
Structural Properties of Two-Dimensional Polymers
We present structural properties of two-dimensional polymers as far as they
can be described by percolation theory. The percolation threshold, critical
exponents and fractal dimensions of clusters are determined by computer
simulation and compared to the results of percolation theory. We also describe
the dependence of the typical cluster structures on the reaction rate.Comment: 7 pages, LaTeX with RevTeX and epsf styles and PostScript figures
included (uuencoded shell archive), TVP-93051
Exponential distributions of collective flow-event properties in viscous liquid dynamics
We study the statistics of flow events in the inherent dynamics in
supercooled two- and three-dimensional binary Lennard-Jones liquids.
Distributions of changes of the collective quantities energy, pressure and
shear stress become exponential at low temperatures, as does that of the event
"size" . We show how the -distribution controls the
others, while itself following from exponential tails in the distributions of
(1) single particle displacements , involving a Lindemann-like length
and (2) the number of active particles (with ).Comment: Accepter version (PRL
Two-way coupling of FENE dumbbells with a turbulent shear flow
We present numerical studies for finitely extensible nonlinear elastic (FENE)
dumbbells which are dispersed in a turbulent plane shear flow at moderate
Reynolds number. The polymer ensemble is described on the mesoscopic level by a
set of stochastic ordinary differential equations with Brownian noise. The
dynamics of the Newtonian solvent is determined by the Navier-Stokes equations.
Momentum transfer of the dumbbells with the solvent is implemented by an
additional volume forcing term in the Navier-Stokes equations, such that both
components of the resulting viscoelastic fluid are connected by a two-way
coupling. The dynamics of the dumbbells is given then by Newton's second law of
motion including small inertia effects. We investigate the dynamics of the flow
for different degrees of dumbbell elasticity and inertia, as given by
Weissenberg and Stokes numbers, respectively. For the parameters accessible in
our study, the magnitude of the feedback of the polymers on the macroscopic
properties of turbulence remains small as quantified by the global energy
budget and the Reynolds stresses. A reduction of the turbulent drag by up to
20% is observed for the larger particle inertia. The angular statistics of the
dumbbells shows an increasing alignment with the mean flow direction for both,
increasing elasticity and inertia. This goes in line with a growing asymmetry
of the probability density function of the transverse derivative of the
streamwise turbulent velocity component. We find that dumbbells get stretched
referentially in regions where vortex stretching or bi-axial strain dominate
the local dynamics and topology of the velocity gradient tensor.Comment: 20 pages, 10 Postscript figures (Figures 5 and 10 in reduced quality
Hostile mood and social strain during daily life: A test of the transactional model.
Hostility is a multidimensional construct related to cardiovascular (CV) disease risk. Daily hostile mood and social interactions may precipitate stress-related CV responses in hostile individuals. Purpose: Determine whether trait cognitive hostility best predicts daily hostile mood and social interactions relative to other trait hostility factors and explore the temporal links between these daily measure
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Positive impact of IPS supported employment on PTSD-related occupational-psychosocial functional outcomes: Results from a VA randomized-controlled trial.
OBJECTIVE: Posttraumatic stress disorder (PTSD) has significant negative effects on occupational, interpersonal, and social functioning. Supported employment is highly effective in helping people with a diagnosis of PTSD obtain and maintain competitive employment. However, less is known about the impact of supported employment on functioning in work or school, social, and interpersonal areas as specifically related to the symptoms of PTSD. METHOD: The Veterans Individual Placement and Support Toward Advancing Recovery study was a prospective, multisite, randomized, controlled trial that compared Individual Placement and Support (IPS) supported employment with a stepwise vocational rehabilitation involving transitional work (TW) assignments with unemployed veterans with PTSD diagnoses (n = 541) at 12 Veterans Administration (VA) medical centers. This analysis focuses on the PTSD-related functional outcomes over the 18-month follow-up period. RESULTS: Compared with those randomized to TW, the PTSD Related Functioning Inventory (PRFI) total score significantly improved for participants randomized to IPS (LSMeans difference = -3.92, 95% CI [-7.49, -.36]; p = .03) over 18 months. When the Work/School subscale of the PRFI was removed from the analysis, the IPS group continued to show significant improvements compared with the TW group on the PRFI relationship and lifestyle domains (LSMeans difference = -2.37, 95% CI [-4.74, .00]; p = .05), suggesting a positive impact of IPS beyond work/school functioning. CONCLUSION: Compared with the usual-care VA vocational services for veterans with PTSD, IPS supported employment is associated with greater improvement in overall PTSD-related functioning, including occupational, interpersonal, and lifestyle domains. In addition to superior employment outcomes, IPS has a positive impact on occupational-psychosocial functioning outcomes. (PsycINFO Database Record (c) 2019 APA, all rights reserved)
Grand-canonical solution of semiflexible self-avoiding trails on the Bethe lattice
11 pages, 7 figures11 pages, 7 figures11 pages, 7 figure
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