55,508 research outputs found
Ground pattern analysis in the Great Plains
There are no author-identified significant results in this report
Evidence from scanning tunneling microscopy in support of a structural model for the InSb(001)-c(8×2) surface
In this letter we present evidence from scanning tunneling microscopy studies in support of a recently proposed structural model for the indium-terminated c(8×2) surface of InSb(001). This structural model, by Norris and co-workers, is based on a surface x-ray diffraction study [Surf. Sci. 409, 27 (1998)], and represents a significant departure from previously suggested models for the c(8×2) reconstruction on any (001) surface of the common III–V semiconductor materials. Although filled state images of the InSb(001)-c(8×2) surface have previously been published, empty states image of sufficient quality to extract any meaningful information have not previously been reported. The observations are in excellent agreement with the recently proposed model for this surface reconstruction
Manifolds associated with -colored regular graphs
In this article we describe a canonical way to expand a certain kind of
-colored regular graphs into closed -manifolds by
adding cells determined by the edge-colorings inductively. We show that every
closed combinatorial -manifold can be obtained in this way. When ,
we give simple equivalent conditions for a colored graph to admit an expansion.
In addition, we show that if a -colored regular graph
admits an -skeletal expansion, then it is realizable as the moment graph of
an -dimensional closed -manifold.Comment: 20 pages with 9 figures, in AMS-LaTex, v4 added a new section on
reconstructing a space with a -action for which its moment graph is
a given colored grap
Momentum distribution of confined bosons: temperature dependence
The momentum distribution function of a parabolically confined gas of bosons
with harmonic interparticle interactions is derived. In the Bose-Einstein
condensation region, this momentum distribution substantially deviates from a
Maxwell-Boltzmann distribution. It is argued that the determination of the
temperature of the boson gas from the Bose-Einstein momentum distribution
function is more appropriate than the currently used fitting to the high
momentum tail of the Maxwell-Boltzmann distribution.Comment: 5 REVTEX pages + 2 postscript figures. Accepted in Phys. Rev.
The Dual Formulation of Cosmic Strings and Vortices
We study four dimensional systems of global, axionic and local strings. By
using the path integral formalism, we derive the dual formulation of these
systems, where Goldstone bosons, axions and missive vector bosons are described
by antisymmetric tensor fields, and strings appear as a source for these tensor
fields. We show also how magnetic monopoles attached to local strings are
described in the dual formulation. We conclude with some remarks.Comment: 18 pages, CU-TP-588 and CERN-TH.6780/9
Vortex Waves in a Cloud of Bose Einstein - Condensed, Trapped Alkali - Metal Atoms
We consider the vortex state solution for a rotating cloud of trapped, Bose
Einstein - condensed alkali atoms and study finite temperature effects. We find
that thermally excited vortex waves can distort the vortex state significantly,
even at the very low temperatures relevant to the experiments.Comment: to appear in Phys. Rev.
Maximal violation of Bell inequalities by position measurements
We show that it is possible to find maximal violations of the CHSH-Bell
inequality using only position measurements on a pair of entangled
non-relativistic free particles. The device settings required in the CHSH
inequality are done by choosing one of two times at which position is measured.
For different assignments of the "+" outcome to positions, namely to an
interval, to a half line, or to a periodic set, we determine violations of the
inequalities, and states where they are attained. These results have
consequences for the hidden variable theories of Bohm and Nelson, in which the
two-time correlations between distant particle trajectories have a joint
distribution, and hence cannot violate any Bell inequality.Comment: 13 pages, 4 figure
A duality relation for fluid spacetime
We consider the electromagnetic resolution of gravitational field. We show
that under the duality transformation, in which active and passive electric
parts of the Riemann curvature are interchanged, a fluid spacetime in comoving
coordinates remains invariant in its character with density and pressure
transforming, while energy flux and anisotropic pressure remaining unaltered.
Further if fluid admits a barotropic equation of state,
where , which will transform to . Clearly the stiff fluid and dust are dual to each-other
while , will go to flat spacetime. However the n and the deSitter ) universes ar e self-dual.Comment: 5 pages, LaTeX version, Accepted in Classical Quantum Gravity as a
Lette
Evaporation of a packet of quantized vorticity
A recent experiment has confirmed the existence of quantized turbulence in
superfluid He3-B and suggested that turbulence is inhomogenous and spreads away
from the region around the vibrating wire where it is created. To interpret the
experiment we study numerically the diffusion of a packet of quantized vortex
lines which is initially confined inside a small region of space. We find that
reconnections fragment the packet into a gas of small vortex loops which fly
away. We determine the time scale of the process and find that it is in order
of magnitude agreement with the experiment.Comment: figure 1a,b,c and d, figure2, figure
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