10,371 research outputs found
Surface-sensitive NMR in optically pumped semiconductors
We present a scheme of surface-sensitive nuclear magnetic resonance in
optically pumped semiconductors, where an NMR signal from a part of the surface
of a bulk compound semiconductor is detected apart from the bulk signal. It
utilizes optically oriented nuclei with a long spin-lattice relaxation time as
a polarization reservoir for the second (target) nuclei to be detected. It
provides a basis for the nuclear spin polarizer [IEEE Trans. Appl. Supercond.
14, 1635 (2004)], which is a polarization reservoir at a surface of the
optically pumped semiconductor that polarizes nuclear spins in a target
material in contact through the nanostructured interfaces.Comment: 4 pages, 5 figure
Deep Space Network utilization for flight projects, calendar year 1981
A report on the utilization of the Deep Space Network during calendar year 1981 in support of all flight projects is presented. The network expended 63% of its total capability in support of Space Flight projects
Regularized Renormalization Group Reduction of Symplectic Map
By means of the perturbative renormalization group method, we study a
long-time behaviour of some symplectic discrete maps near elliptic and
hyperbolic fixed points. It is shown that a naive renormalization group (RG)
map breaks the symplectic symmetry and fails to describe a long-time behaviour.
In order to preserve the symplectic symmetry, we present a regularization
procedure, which gives a regularized symplectic RG map describing an
approximate long-time behaviour succesfully
Effects of Squark Processes on the Axino CDM Abundance
We investigate the role of an effective dimension-4 axino-quark-squark
coupling in the thermal processes producing stable cold axino relics in the
early Universe. We find that, while the induced squark and quark scattering
processes are always negligible, squark decays become important in the case of
low reheat temperature and large gluino mass. The effect can tighten the bounds
on the scenario from the requirement that cold dark matter axinos do not
overclose the Universe.Comment: 20 pages, 9 figures, uses JHEP3.cl
Variation of the first Hilbert coefficients of parameters with a common integral closure
A problem posed by Wolmer V. Vasconcelos on the variation of the first
Hilbert coefficients of parameter ideals with a common integral closure in a
local ring is studied. Affirmative answers are given and counterexamples are
explored as well
Nonabelian Gauge Theories on Noncommutative Spaces
In this paper, we describe a method for obtaining the nonabelian
Seiberg-Witten map for any gauge group and to any order in theta. The equations
defining the Seiberg-Witten map are expressed using a coboundary operator, so
that they can be solved by constructing a corresponding homotopy operator. The
ambiguities, of both the gauge and covariant type, which arise in this map are
manifest in our formalism.Comment: 14 pages, latex, Talk presented at 2001: A Spacetime Odyssey -
Michigan Center for Theoretical Physics, some typos correcte
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