130,156 research outputs found
A generalization of contact metric manifolds
We give a characterization of a contact metric manifold as a special almost
contact metric manifold and discuss an almost contact metric manifold which is
{a} natural generalization of the contact metric manifolds introduced by Y.
Tashiro.Comment: 15 page
A proof of the Chern-Gauss-Bonnet theorem for indefinite signature metrics using analytic continuation
We derive the Chern-Gauss-Bonnet Theorem for manifolds with smooth
non-degenerate boundary in the pseudo-Riemannian context from the corresponding
result in the Riemannian setting by examining the Euler-Lagrange equations
associated to the Pfaffian of a complex "metric" on the tangent space and then
applying analytic continuation.Comment: This paper has been withdrawn by the authors. A later improved
version is available upon request from the authors but will not be posted to
the arXi
Nanoscale Topographical Replication of Graphene Architecture by Artificial DNA nanostructures
Despite many studies on how geometry can be used to control the electronic
properties of graphene, certain limitations to fabrication of designed graphene
nanostructures exist. Here, we demonstrate controlled topographical replication
of graphene by artificial deoxyribonucleic acid (DNA) nanostructures. Owing to
the high degree of geometrical freedom of DNA nanostructures, we controlled the
nanoscale topography of graphene. The topography of graphene replicated from
DNA nanostructures showed enhanced thermal stability and revealed an
interesting negative temperature coefficient of sheet resistivity when
underlying DNA nanostructures were denatured at high temperatures.Comment: 12 pages, 3 figure
Strong Confinement and Oscillations in Two-Component Bose-Einstein Condensates
We present a new model of BEC dynamics based on strong confinement near the
ground state. The model predicts oscillations in a two-component condensate,
based on interference of non-spreading wave packets moving within a pair of
tilted nearly square potentials. The oscillations are similar to those recently
reported for a magnetically trapped Rb condensate, and the model's
predictions give good quantitative agreement with the experiments.Comment: 4 pages, 8 figure
Fabrication of Analog Electronics for Serial Readout of Silicon Strip Sensors
A set of analog electronics boards for serial readout of silicon strip
sensors was fabricated. A commercially available amplifier is mounted on a
homemade hybrid board in order to receive analog signals from silicon strip
sensors. Also, another homemade circuit board is fabricated in order to
translate amplifier control signals into a suitable format and to provide bias
voltage to the amplifier as well as to the silicon sensors. We discuss
technical details of the fabrication process and performance of the circuit
boards we developed.Comment: minor typos corrected, and additional acknowledgement included. To be
submitted to JINS
Correction to "minimal unit vector fields"
The paper "Minimal unit vector fields" by O. Gil-Medrano and E.
Llinares-Fuster \cite{GilLli1}. is a seminal paper in the field that has been
cited by many authors. It contains, however, a minor technical mistake in
Theorem 14 that is important to fix. In this short note, we will provide a
correction to that result.Comment: 8page
Complex sine-Gordon Theory for Coherent Optical Pulse Propagation
It is shown that the McCall-Hahn theory of self-induced transparency in
coherent optical pulse propagation can be identified with the complex
sine-Gordon theory in the sharp line limit. We reformulate the theory in terms
of the deformed gauged Wess-Zumino-Witten sigma model and address various new
aspects of self-induced transparency.Comment: 8 pages, in Late
Nonabelian sine-Gordon theory and its application to nonlinear optics
Using a field theory generalization of the spinning top motion, we construct
nonabelian generalizations of the sine-Gordon theory according to each
symmetric spaces. A Lagrangian formulation of these generalized sine-Gordon
theories is given in terms of a deformed gauged Wess-Zumino-Witten action which
also accounts for integrably perturbed coset conformal field theories. As for
physical applications, we show that they become precisely the effective field
theories of self-induced transparency in nonlinear optics. This provides a
dictionary between field theory and nonlinear optics.Comment: 5 pages, to appear in the Proceedings of the 2nd Sakharov Conference
on Physics, Moscow, May, 199
Field Theory for Coherent Optical Pulse Propagation
We introduce a new notion of "matrix potential" to nonlinear optical systems.
In terms of a matrix potential , we present a gauge field theoretic
formulation of the Maxwell-Bloch equation that provides a semiclassical
description of the propagation of optical pulses through resonant multi-level
media. We show that the Bloch part of the equation can solved identically
through and the remaining Maxwell equation becomes a second order
differential equation with reduced set of variables due to the gauge invariance
of the system. Our formulation clarifies the (nonabelian) symmetry structure of
the Maxwell-Bloch equations for various multi-level media in association with
symmetric spaces . In particular, we associate nondegenerate two-level
system for self-induced transparency with and three-level \L
- or V-systems with . We give a detailed analysis for the
two-level case in the matrix potential formalism, and address various new
properties of the system including soliton numbers, effective potential energy,
gauge and discrete symmetries, modified pulse area, conserved topological and
nontopological charges. The nontopological charge measures the amount of
self-detuning of each pulse. Its conservation law leads to a new type of pulse
stability analysis which explains nicely earlier numerical results.Comment: 43 pages, Latex, some comments and references are added. postscript
file containing 10 figures can be obtained at
http://photon.kyunghee.ac.kr/~qhpark
Saturated actions by finite dimensional Hopf *-algebras on C*-algebras
If a finite group action on a unital -algebra is saturated,
the canonical conditional expectation onto the fixed point
algebra is known to be of index finite type with in the sense of
Watatani. More generally if a finite dimensional Hopf -algebra acts on
and the action is saturated, the same is true with . In
this paper we prove that the converse is true. Especially in case is a
commutative -algebra and is a finite group action, we give
an equivalent condition in order that the expectation
is of index finite type, from which we obtain that is saturated if and
only if acts freely on .
Actions by compact groups are also considered to show that the gauge action
on a graph -algebra associated with a locally finite
directed graph is saturated.Comment: 18 pages, to be published in Intern. J. Mat
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