8,578 research outputs found
Low temperature shape relaxation of 2-d islands by edge diffusion
We present a precise microscopic description of the limiting step for low
temperature shape relaxation of two dimensional islands in which activated
diffusion of particles along the boundary is the only mechanism of transport
allowed. In particular, we are able to explain why the system is driven
irreversibly towards equilibrium. Based on this description, we present a
scheme for calculating the duration of the limiting step at each stage of the
relaxation process. Finally, we calculate numerically the total relaxation time
as predicted by our results and compare it with simulations of the relaxation
process.Comment: 11 pages, 5 figures, to appear in Phys. Rev.
Self-organized metal nanostructures through laser driven thermocapillary convection
When ultrathin metal films are subjected to multiple cycles of rapid melting
and resolidification by a ns pulsed laser, spatially correlated interfacial
nanostructures can result from a competition among several possible thin film
self-organizing processes. Here we investigate self-organization and the
ensuing length scales when Co films (1-8 nm thick) on SiO_{\text{2}} surfaces
are repeatedly and rapidly melted by non-uniform (interference) laser
irradiation. Pattern evolution produces nanowires, which eventually break-up
into nanoparticles exhibiting spatial order in the nearest neighbor spacing,
\lambda_{NN2}.The scaling behavior is consistent with pattern formation by
thermocapillary flow and a Rayleigh-like instability. For h_{0}\leq2 nm, a
hydrodynamic instability of a spinodally unstable film leads to the formation
of nanoparticles.Comment: 10 pages, 3 figure
Closed Universes With Black Holes But No Event Horizons As a Solution to the Black Hole Information Problem
We show it is possible for the information paradox in black hole evaporation
to be resolved classically. Using standard junction conditions, we attach the
general closed spherically symmetric dust metric to a spacetime satisfying all
standard energy conditions but with a single point future c-boundary. The
resulting Omega Point spacetime, which has NO event horizons, nevertheless has
black hole type trapped surfaces and hence black holes. But since there are no
event horizons, information eventually escapes from the black holes. We show
that a scalar quintessence field with an appropriate exponential potential near
the final singularity would give rise to an Omega Point final singularity.Comment: 27 pages in LaTex2e, no figure
Duality between quantum symmetric algebras
Using certain pairings of couples, we obtain a large class of two-sided
non-degenerated graded Hopf pairings for quantum symmetric algebras.Comment: 15 pages. Letters in Math. Phy., to appear soo
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