4,882 research outputs found
Collision of Polymers in a Vacuum
In a number of experimental situations, single polymer molecules can be
suspended in a vacuum. Here collisions between such molecules are considered.
The limit of high collision velocity is investigated numerically for a variety
of conditions. The distribution of contact times, scattering angles, and final
velocities are analyzed. In this limit, self avoiding chains are found to
become highly stretched as they collide with each other, and have a
distribution of scattering times that depends on the scattering angle. The
velocity of the molecules after the collisions is similar to predictions of a
model assuming thermal equilibration of molecules during the collision. The
most important difference is a significant subset of molecules that
inelastically scatter but do not substantially change direction.Comment: 7 pages, 6 figure
H\"older Regularity of Geometric Subdivision Schemes
We present a framework for analyzing non-linear -valued
subdivision schemes which are geometric in the sense that they commute with
similarities in . It admits to establish
-regularity for arbitrary schemes of this type, and
-regularity for an important subset thereof, which includes all
real-valued schemes. Our results are constructive in the sense that they can be
verified explicitly for any scheme and any given set of initial data by a
universal procedure. This procedure can be executed automatically and
rigorously by a computer when using interval arithmetics.Comment: 31 pages, 1 figur
Almost Certain Escape from Black Holes
This paper examines how black holes might compute in light of recent models
of the black-hole final state. These models suggest that quantum information
can escape from the black hole by a process akin to teleportation. They require
a specific final state and restrictions on the interaction between the
collapsing matter and the incoming Hawking radiation for quantum information to
escape. This paper shows that for an arbitrary final state and for generic
interactions between matter and Hawking radiation, the quantum information
about how the hole was formed and the results of any computation performed by
the matter inside the hole escapes with fidelity exponentially close to 1.Comment: 9 Pages, Te
Addressing the Racial Disparity in Birth Outcomes: Implications for Maternal Racial Identity on Birthweight
Background: As a widely used marker of health, birthweight has been a persistent racialized disparity with the low birthweight rate of Blacks in Alabama nearly doubling the national average. The purpose of this study was to examine the role of racial identity and acculturation on birthweight in a sample of Black women living in Alabama.
Methods: Black women (n=72) in West Alabama were surveyed about the birthweight of their first born child. Correlation and multiple linear regression analyses were conducted.
Results: Racial identity was the only significant predictor of birthweight. Mothers with a strong racial identity reported having low birthweight babies less often than those who scored lower on racial identity. Further exploration of racial identity revealed self-image as the essential element that predicted birthweight. Birthweight increased 4.2 ounces for each additional degree of self-image. Results also indicated that birthweight decreased as mothers’ age increased, within the widely accepted optimal maternal age range 21 to 35.
Conclusions: Results add to the existing body of literature in support of the positive effects racial identity has on health. Findings on age are congruent with the weathering hypothesis which states that the health of Black women may begin to deteriorate in early adulthood possibly due to the strain of racism
Thermally assisted quantum cavitation in solutions of 3He in 4He
We have investigated the quantum-to-thermal crossover temperature T* for
cavitation in liquid helium mixtures up to 0.05 3He concentrations. With
respect to the pure 4He case, T* is sizeably reduced, to a value below 50 mK
for 3He concentrations above 0.02. As in pure 4He, the homogeneous cavitation
pressure is systematically found close to the spinodal pressure.Comment: Typeset using Revtex, 9 pages and 4 figure
Distribution of occupation numbers in finite Fermi-systems and role of interaction in chaos and thermalization
New method is developed for calculation of single-particle occupation numbers
in finite Fermi systems of interacting particles. It is more accurate than the
canonical distribution method and gives the Fermi-Dirac distribution in the
limit of large number of particles. It is shown that statistical effects of the
interaction are absorbed by an increase of the effective temperature. Criteria
for quantum chaos and statistical equilibrium are considered. All results are
confirmed by numerical experiments in the two-body random interaction model.Comment: 4 pages, Latex, 4 figures in the form of PS-file
Collective pinning of imperfect vortex lattices by material line defects in extreme type-II superconductors
The critical current density shown by a superconductor at the extreme type-II
limit is predicted to follow an inverse square-root power law with external
magnetic field if the vortex lattice is weakly pinned by material line defects.
It acquires an additional inverse dependence with thickness along the line
direction once pinning of the interstitial vortex lines by material point
defects is included. Moderate quantitative agreement with the critical current
density shown by second-generation wires of high-temperature superconductors in
kG magnetic fields is achieved at liquid-nitrogen temperature.Comment: 10 pages, 3 figures, 2 tables. To appear in Physical Review
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