2,923 research outputs found
Minimal surfaces with positive genus and finite total curvature in
We construct the first examples of complete, properly embedded minimal
surfaces in with finite total curvature and
positive genus. These are constructed by gluing copies of horizontal catenoids
or other nondegenerate summands. We also establish that every horizontal
catenoid is nondegenerate.
Finally, using the same techniques, we are able to produce properly embedded
minimal surfaces with infinitely many ends. Each annular end has finite total
curvature and is asymptotic to a vertical totally geodesic plane.Comment: 32 pages, 4 figures. This revised version will appear in Geometry and
Topolog
Lp-cohomology of negatively curved manifolds
We compute the -cohomology spaces of some negatively curved manifolds.
We deal with two cases: manifolds with finite volume and sufficiently pinched
negative curvature, and conformally compact manifolds
Preroughening, Diffusion, and Growth of An FCC(111) Surface
Preroughening of close-packed fcc(111) surfaces, found in rare gas solids, is
an interesting, but poorly characterized phase transition. We introduce a
restricted solid-on-solid model, named FCSOS, which describes it. Using mostly
Monte Carlo, we study both statics, including critical behavior and scattering
properties, and dynamics, including surface diffusion and growth. In antiphase
scattering, it is shown that preroughening will generally show up at most as a
dip. Surface growth is predicted to be continuous at preroughening, where
surface self-diffusion should also drop. The physical mechanism leading to
preroughening on rare gas surfaces is analysed, and identified in the step-step
elastic repulsion.Comment: Revtex + uuencoded figures, to appear in Physical Review Letter
Charge dynamics of a single donor coupled to a few electrons quantum dot in silicon
We study the charge transfer dynamics between a silicon quantum dot and an
individual phosphorous donor using the conduction through the quantum dot as a
probe for the donor ionization state. We use a silicon n-MOSFET (metal oxide
field effect transistor) biased near threshold in the SET regime with two side
gates to control both the device conductance and the donor charge. Temperature
and magnetic field independent tunneling time is measured. We measure the
statistics of the transfer of electrons observed when the ground state D0 of
the donor is aligned with the SET states
Self similar expanding solutions of the planar network flow
We prove the existence of self-similar expanding solutions of the curvature flow on planar networks where the initial configuration is any number of half-lines meeting at the origin. This generalizes recent work by Schn\"urer and Schulze which treats the case of three half-lines. There are multiple solutions, and these are parametrized by combinatorial objects, namely Steiner trees with respect to a complete negatively curved metric on the unit ball which span specified points on the boundary at infinity. We also provide a sharp formulation of the regularity of these solutions at
Differentiation Strategy and Market Deregulation: Local Telecommunication Entry in the Late 1990s
The authors examine the role of differentiation strategies for entry behavior in markets for local telecommunication services in the late 1990s. Whereas the prior literature has used models of interaction among homogenous firms, this research is motivated by the claim of entrants that they differ substantially in their product offerings and business strategies. Exploiting a new, detailed data set of Competitive Local Exchange Carriers (CLECs) entry into over 700 U.S. cities, the authors take advantage of recent developments in the analysis of entry and competition among differentiated firms. They test and reject the null hypothesis of homogeneous competitors. They also find strong evidence that CLECs account for both potential market demand and the business strategies of competitors when making their entry decisions. This suggests that firms' incentives to differentiate their services should shape the policy debate for competitive local telecommunications
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