14,258 research outputs found
On Quadratic Inverses for Quadratic Permutation Polynomials over Integer Rings
An interleaver is a critical component for the channel coding performance of
turbo codes. Algebraic constructions are of particular interest because they
admit analytical designs and simple, practical hardware implementation. Sun and
Takeshita have recently shown that the class of quadratic permutation
polynomials over integer rings provides excellent performance for turbo codes.
In this correspondence, a necessary and sufficient condition is proven for the
existence of a quadratic inverse polynomial for a quadratic permutation
polynomial over an integer ring. Further, a simple construction is given for
the quadratic inverse. All but one of the quadratic interleavers proposed
earlier by Sun and Takeshita are found to admit a quadratic inverse, although
none were explicitly designed to do so. An explanation is argued for the
observation that restriction to a quadratic inverse polynomial does not narrow
the pool of good quadratic interleavers for turbo codes.Comment: Submitted as a Correspondence to the IEEE Transactions on Information
Theory Submitted : April 1, 2005 Revised : Nov. 15, 200
Comparisons of monthly mean cosmic ray counting rates observes from worldwide network of neutron monitors
In order to examine the stability of neutron monitor observation, each of the monthly average counting rates of a neutron monitors is correlated to those of Kiel neutron monitor. The regression coefficients thus obtained are compared with the coupling coefficients of isotropic intensity radiation. The results of the comparisons for five year periods during 1963 to 1982, and for whole period are given. The variation spectrum with a single power law with an exponent of -0.75 up to 50 GV is not so unsatisfactory one. More than one half of the stations show correlations with the coefficient greater than 0.9. Some stations have shifted the level of mean counting rates by changing the instrumental characteristics which can be adjusted
Neutron Stars with Bose-Einstein Condensation of Antikaons as MIT Bags
We investigate the properties of an antikaon in medium, regarding itas a MIT
bag. We first construct the MIT bag model for a kaon with and
in order to describe the interaction of-quarks in hyperonic matter in the
framework of the modifiedquark-meson coupling model. The coupling constant
in the density-dependent bag constant is treated
as afree parameter to reproduce the optical potential of a kaon in asymmetric
matter and all other couplings are determined by usingSU(6) symmetry and the
quark counting rule. With various values ofthe kaon potential, we calculate the
effective mass of a kaon inmedium to compare it with that of a point-like kaon.
We thencalculate the population of octet baryons, leptons and and
theequation of state for neutron star matter. The results show thatkaon
condensation in hyperonic matter is sensitive to the -quarkinteraction and
also to the way of treating the kaon. The mass andthe radius of a neutron star
are obtained by solving theTolmann-Oppenheimer-Volkoff equation.Comment: 14 figure
From orbifolding conformal field theories to gauging topological phases
Topological phases of matter in (2+1) dimensions are commonly equipped with
global symmetries, such as electric-magnetic duality in gauge theories and
bilayer symmetry in fractional quantum Hall states. Gauging these symmetries
into local dynamical ones is one way of obtaining exotic phases from
conventional systems. We study this using the bulk-boundary correspondence and
applying the orbifold construction to the (1+1) dimensional edge described by a
conformal field theory (CFT). Our procedure puts twisted boundary conditions
into the partition function, and predicts the fusion, spin and braiding
behavior of anyonic excitations after gauging. We demonstrate this for the
electric-magnetic self-dual gauge theory, the twofold symmetric
, and the -symmetric Wess-Zumino-Witten theories.Comment: 23 pages, 1 figur
Empirical Comparisons of Virtual Environment Displays
There are many different visual display devices used in virtual environment (VE) systems. These displays vary along many dimensions, such as resolution, field of view, level of immersion, quality of stereo, and so on. In general, no guidelines exist to choose an appropriate display for a particular VE application. Our goal in this work is to develop such guidelines on the basis of empirical results. We present two initial experiments comparing head-mounted displays with a workbench display and a foursided spatially immersive display. The results indicate that the physical characteristics of the displays, users' prior experiences, and even the order in which the displays are presented can have significant effects on performance
Effective response theory for zero energy Majorana bound states in three spatial dimensions
We propose a gravitational response theory for point defects (hedgehogs)
binding Majorana zero modes in (3+1)-dimensional superconductors. Starting in
4+1 dimensions, where the point defect is extended into a line, a coupling of
the bulk defect texture with the gravitational field is introduced.
Diffeomorphism invariance then leads to an Kac-Moody current running
along the defect line. The Kac-Moody algebra accounts for the
non-Abelian nature of the zero modes in 3+1 dimensions. It is then shown to
also encode the angular momentum density which permeates throughout the bulk
between hedgehog-anti-hedgehog pairs.Comment: 7 pages, 3 figure
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