423 research outputs found
Numerical Study of Wave Propagation in Uniaxially Anisotropic Lorentzian Backward Wave Slabs
The propagation and refraction of a cylindrical wave created by a line
current through a slab of backward wave medium, also called left-handed medium,
is numerically studied with FDTD. The slab is assumed to be uniaxially
anisotropic. Several sets of constitutive parameters are considered and
comparisons with theoretical results are made. Electric field distributions are
studied inside and behind the slab. It is found that the shape of the
wavefronts and the regions of real and complex wave vectors are in agreement
with theoretical results.Comment: 6 pages, figure
Low Space External Memory Construction of the Succinct Permuted Longest Common Prefix Array
The longest common prefix (LCP) array is a versatile auxiliary data structure
in indexed string matching. It can be used to speed up searching using the
suffix array (SA) and provides an implicit representation of the topology of an
underlying suffix tree. The LCP array of a string of length can be
represented as an array of length words, or, in the presence of the SA, as
a bit vector of bits plus asymptotically negligible support data
structures. External memory construction algorithms for the LCP array have been
proposed, but those proposed so far have a space requirement of words
(i.e. bits) in external memory. This space requirement is in some
practical cases prohibitively expensive. We present an external memory
algorithm for constructing the bit version of the LCP array which uses
bits of additional space in external memory when given a
(compressed) BWT with alphabet size and a sampled inverse suffix array
at sampling rate . This is often a significant space gain in
practice where is usually much smaller than or even constant. We
also consider the case of computing succinct LCP arrays for circular strings
Spacelike Wilson Loops at Finite Temperature
In the high temperature phase of Yang-Mills theories, large spatial Wilson
loops show area law behaviour with a string tension that grows with increasing
temperature. Within the framework of the commonly used string picture we use a
large scale expansion, which allows us to determine the string tension from
measurements of intermediate and symmetric Wilson loops.Comment: Tex file. No figures included. Obtainable from P. Lacock at email
address: [email protected]
High Temperature 3D QCD: Dimensional Reduction at Work
We investigate the three-dimensional SU(3) gauge theory at finite temperature
in the framework of dimensional reduction. The large scale properties of this
theory are expected to be conceptually more complicated than in four
dimensions. The dimensionally reduced action is computed in closed analytical
form. The resulting effective two-dimensional theory is studied numerically
both in the electric and magnetic sector. We find that dimensional reduction
works excellently down to temperatures of 1.5 times the deconfinement phase
transition temperature and even on rather short length scales. We obtain strong
evidence that for , even at high temperature the colour averaged
potential is represented by the exchange of a single state, at variance with
the usual Debye screening picture involving a pair of electric gluons.Comment: 27 page
Density Functional Theory of Multicomponent Quantum Dots
Quantum dots with conduction electrons or holes originating from several
bands are considered. We assume the particles are confined in a harmonic
potential and assume the electrons (or holes) belonging to different bands to
be different types of fermions with isotropic effective masses. The density
functional method with the local density approximation is used. The increased
number of internal (Kohn-Sham) states leads to a generalisation of Hund's first
rule at high densities. At low densitites the formation of Wigner molecules is
favored by the increased internal freedom.Comment: 11 pages, 5 figure
Wave Energy: a Pacific Perspective
This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The Royal Society and can be found at: http://rsta.royalsocietypublishing.org/.This paper illustrates the status of wave energy development in Pacific Rim countries by characterizing the available resource and introducing the region‟s current and potential future leaders in wave energy converter development. It also describes the existing licensing and permitting process as well as potential environmental concerns. Capabilities of Pacific Ocean testing facilities are described in addition to the region‟s vision of the future of wave energy
Screening Masses of Hot SU(2) Gauge Theory from the 3D Adjoint Higgs Model
We study the Landau gauge propagators of the lattice SU(2) 3d adjoint Higgs
model, considered as an effective theory of high temperature 4d SU(2) gauge
theory. From the long distance behaviour of the propagators we extract the
screening masses. It is shown that the pole masses extracted from the
propagators agree well with the screening masses obtained recently in finite
temperature SU(2) theory. The relation of the propagator masses to the masses
extracted from gauge invariant correlators is also discussed. In so-called
lambda gauges non-perturbative evidence is given for the gauge independence of
pole masses within this class of gauges.Comment: Talk given at SEWM98 Conference, Copenhagen, December 199
Stance and affect in conversation: on the interplay of sequential and phonetic resources
Linguists, and other analysts of discourse, regularly make appeal to affectual states in determining the meaning of utterances. We examine two kinds of sequence that occur in everyday conversation. The first involves one participant making an explicit lexical formulation of a co-participant's affectual state (e.g., ‘you sound happy’, ‘don't sound so depressed’). The second involves responses to ‘positive informings’ and ‘negative informings’. Through consideration of sequential organization, participant orientation, and phonetic detail, we suggest that the attribution of analytic categories of affect is problematic. We argue that phonetic characteristics which might be thought to be associated with affect may better be accounted for with reference to the management of particular sequential-interactional tasks. The finding that stance does not inhere in any single turn at talk or any single linguistic aspect leads us to suggest that future investigations into stance and affect will need to pay attention simultaneously to matters of both linguistic-phonetic and sequential organization
Parallel String Sample Sort
We discuss how string sorting algorithms can be parallelized on modern
multi-core shared memory machines. As a synthesis of the best sequential string
sorting algorithms and successful parallel sorting algorithms for atomic
objects, we propose string sample sort. The algorithm makes effective use of
the memory hierarchy, uses additional word level parallelism, and largely
avoids branch mispredictions. Additionally, we parallelize variants of multikey
quicksort and radix sort that are also useful in certain situations.Comment: 34 pages, 7 figures and 12 table
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