69,782 research outputs found
Shape Instabilities in the Dynamics of a Two-component Fluid Membrane
We study the shape dynamics of a two-component fluid membrane, using a
dynamical triangulation monte carlo simulation and a Langevin description.
Phase separation induces morphology changes depending on the lateral mobility
of the lipids. When the mobility is large, the familiar labyrinthine spinodal
pattern is linearly unstable to undulation fluctuations and breaks up into
buds, which move towards each other and merge. For low mobilities, the membrane
responds elastically at short times, preferring to buckle locally, resulting in
a crinkled surface.Comment: 4 pages, revtex, 3 eps figure
A Tight Lower Bound on the Sub-Packetization Level of Optimal-Access MSR and MDS Codes
The first focus of the present paper, is on lower bounds on the
sub-packetization level of an MSR code that is capable of carrying out
repair in help-by-transfer fashion (also called optimal-access property). We
prove here a lower bound on which is shown to be tight for the case
by comparing with recent code constructions in the literature.
We also extend our results to an MDS code over the vector alphabet.
Our objective even here, is on lower bounds on the sub-packetization level
of an MDS code that can carry out repair of any node in a subset of
nodes, where each node is repaired (linear repair) by
help-by-transfer with minimum repair bandwidth. We prove a lower bound on
for the case of . This bound holds for any and
is shown to be tight, again by comparing with recent code constructions in the
literature. Also provided, are bounds for the case .
We study the form of a vector MDS code having the property that we can repair
failed nodes belonging to a fixed set of nodes with minimum repair
bandwidth and in optimal-access fashion, and which achieve our lower bound on
sub-packetization level . It turns out interestingly, that such a code
must necessarily have a coupled-layer structure, similar to that of the Ye-Barg
code.Comment: Revised for ISIT 2018 submissio
A Novel Monte Carlo Approach to the Dynamics of Fluids --- Single Particle Diffusion, Correlation Functions and Phase Ordering of Binary Fluids
We propose a new Monte Carlo scheme to study the late-time dynamics of a
2-dim hard sphere fluid, modeled by a tethered network of hard spheres.
Fluidity is simulated by breaking and reattaching the flexible tethers. We
study the diffusion of a tagged particle, and show that the velocity
autocorrelation function has a long-time tail. We investigate the
dynamics of phase separation of a binary fluid at late times, and show that the
domain size grows as for high viscosity fluids with a
crossover to for low viscosity fluids. Our scheme can accomodate
particles interacting with a pair potential ,and modified to study
dynamics of fluids in three dimensions.Comment: Latex, 4 pages, 4 figure
Magnetization and Magneto-resistance in Y(Ba1-xSrx)2Cu3O7-{\delta} (x = 0.00 - 0.50) superconductor
Here we present the magnetic properties and upper critical field (BC2) of
polycrystalline Y(Ba1-xSrx)2Cu3O7-{\delta} superconductors, which are being
determined through detailed ac/dc susceptibility and resistivity under magnetic
field (RTH) study. All the samples are synthesized through solid state reaction
route. Reduction in Meissner fraction (the ratio of field cooled to zero field
cooled magnetization) is observed with increasing Sr content, suggesting
occurrence of flux pining in the doped samples. The ac susceptibility and
resistivity measurements reveal improved grain couplings in Sr substituted
samples. Consequently the inter-grain critical current density (Jc), upturn
curvature near the Tc in temperature dependence of upper critical field
[BC2(T)], and BC2 are enhanced. Both Jc and BC2 increase in lower Sr
substitution (up to x = 0.10) samples followed by decrease in higher doping due
to degradation in effective pining and grain coupling.Comment: 17 pages text + Figs, [email protected]
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