7,135 research outputs found
Dynamical Instabilities and Deterministic Chaos in Ballistic Electron Motion in Semiconductor Superlattices
We consider the motion of ballistic electrons within a superlattice miniband
under the influence of an alternating electric field. We show that the
interaction of electrons with the self-consistent electromagnetic field
generated by the electron current may lead to the transition from regular to
chaotic dynamics. We estimate the conditions for the experimental observation
of this deterministic chaos and discuss the similarities of the superlattice
system with the other condensed matter and quantum optical systems.Comment: 6 pages, RevTEX; 4 fig
Effect of Wave Length Bands of Filtered Light on Germination of Seeds of Kentucky Bluegrass (Poa Pratensis)
Botanists have long known that light, supplied during the germination period, may increase germination percentages. Most studies concerning the effects of light on the germination of seeds have utilized the entire visible spectrum. Only a few workers have studied the effects of various portions of the spectrum. However, results of these studies, dealing with a number of species, have not been consistent. The effect of color of light on germination of Kentucky bluegrass seed has not been previously investigated. Since it is a light sensitive species it was felt that such a study would provide additional basic information on the problem of wave length effect. Because of the limited amount of work which has been done on the effects of wave length of light on the germination of seeds, the literature review includes most of the previous work as a matter of information rather than because it has a direct bearing on the work with Kentucky bluegrass
Non-perturbative results for the spectrum of surface-disordered waveguides
We calculated the spectrum of normal scalar waves in a planar waveguide with
absolutely soft randomly rough boundaries beyond the perturbation theories in
the roughness heights and slopes, basing on the exact boundary scattering
potential. The spectrum is proved to be a nearly real non-analytic function of
the dispersion of the roughness heights (with square-root
singularity) as . The opposite case of large boundary defects is
summarized.Comment: REVTEX 3, OSA style, 9 pages, no figures. Submitted to Optics Letter
Image of the Burau Representation at -th Roots of unity
We prove that the image of the Full braid group on strands
under the Burau representation, evaluated at a primitive -th root of unity
is arithmetic provided .Comment: To appear in Annals of Mathematics. arXiv admin note: text overlap
with arXiv:1204.477
An explicit KO-degree map and applications
The goal of this note is to study the analog in unstable -homotopy theory of the unit map from the motivic sphere spectrum to the
Hermitian K-theory spectrum, i.e., the degree map in Hermitian K-theory. We
show that "Suslin matrices", which are explicit maps from odd dimensional split
smooth affine quadrics to geometric models of the spaces appearing in Bott
periodicity in Hermitian K-theory, stabilize in a suitable sense to the unit
map. As applications, we deduce that for ,
which can be thought of as an extension of Matsumoto's celebrated theorem
describing of a field. These results provide the first step in a program
aimed at computing the sheaf for .Comment: 36 Pages, Final version, to appear Journal of Topolog
Harnack Inequality and Regularity for a Product of Symmetric Stable Process and Brownian Motion
In this paper, we consider a product of a symmetric stable process in
and a one-dimensional Brownian motion in . Then we
define a class of harmonic functions with respect to this product process. We
show that bounded non-negative harmonic functions in the upper-half space
satisfy Harnack inequality and prove that they are locally H\"older continuous.
We also argue a result on Littlewood-Paley functions which are obtained by the
-harmonic extension of an function.Comment: 23 page
Transition from subbarrier to deep subbarrier regimes in heavy-ion fusion reactions
We analyze the recent experimental data of heavy-ion fusion cross sections
available up to deep subbarrier energies in order to discuss the threshold
incident energy for a deep subbarrier fusion hindrance phenomenon. To this end,
we employ a one-dimensional potential model with a Woods-Saxon internuclear
potential. Fitting the experimental data in two different energy regions with
different Woods-Saxon potentials, we define the threshold energy as an
intersect of the two fusion excitation functions. We show that the threshold
energies so extracted are in good agreement with the empirical systematics as
well as with the values of the Krappe-Nix-Sierk (KNS) potential at the touching
point. We also discuss the asymptotic energy shift of fusion cross sections
with respect to the potential model calculations, and show that it decreases
with decreasing energies in the deep subbarrier region although it takes a
constant value at subbarrier energies.Comment: 4 pages, 4 figure
Marketing Percolation
A percolation model is presented, with computer simulations for
illustrations, to show how the sales of a new product may penetrate the
consumer market. We review the traditional approach in the marketing
literature, which is based on differential or difference equations similar to
the logistic equation (Bass 1969). This mean field approach is contrasted with
the discrete percolation on a lattice, with simulations of "social percolation"
(Solomon et al 2000) in two to five dimensions giving power laws instead of
exponential growth, and strong fluctuations right at the percolation threshold.Comment: to appear in Physica
Ultraviolet atomic emission detector
A device and method are provided for performing qualitative and quantitative elemental analysis through the utilization of a vacuum UV chromatographic detector. The method involves the use of a carrier gas at low pressure. The gas carries a sample to a gas chromatograph column; the column output is directed to a microwave cavity. In this cavity, a low pressure microwave discharge produces fragmentation of the compounds present and generates intense atomic emissions in the vacuum ultraviolet. These emissions are isolated by a monochromator and measured by photometer to establish absolute concentration for the elements
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