1,286 research outputs found
Fast phonetic similarity search over large repositories
Analysis of unstructured data may be inefficient in the presence of spelling errors. Existing approaches use string similarity methods to search for valid words within a text, with a supporting dictionary. However, they are not rich enough to encode phonetic information to assist the search. In this paper, we present a novel approach for efficiently perform phonetic similarity search over large data sources, that uses a data structure called PhoneticMap to encode language-specific phonetic information. We validate our approach through an experiment over a data set using a Portuguese variant of a well-known repository, to automatically correct words with spelling errors
Two-temperature relaxation and melting after absorption of femtosecond laser pulse
The theory and experiments concerned with the electron-ion thermal relaxation
and melting of overheated crystal lattice constitute the subject of this paper.
The physical model includes two-temperature equation of state, many-body
interatomic potential, the electron-ion energy exchange, electron thermal
conductivity, and optical properties of solid, liquid, and two phase
solid-liquid mixture. Two-temperature hydrodynamics and molecular dynamics
codes are used. An experimental setup with pump-probe technique is used to
follow evolution of an irradiated target with a short time step 100 fs between
the probe femtosecond laser pulses. Accuracy of measurements of reflection
coefficient and phase of reflected probe light are ~1% and \sim 1\un{nm},
respectively. It is found that,
{\it firstly}, the electron-electron collisions make a minor contribution to
a light absorbtion in solid Al at moderate intensities;
{\it secondly}, the phase shift of a reflected probe results from heating of
ion subsystem and kinetics of melting of Al crystal during 0
where is time delay between the pump and probe pulses measured from the
maximum of the pump;
{\it thirdly} the optical response of Au to a pump shows a marked contrast to
that of Al on account of excitation of \textit{d}-electronsComment: 6th International Conference on Photo-Excited Processes and
Applications 9-12 Sep 2008, Sapporo, Japan, http://www.icpepa6.com, the
contributed paper will be published in Applied Surface Science(2009
Self-consistent approach for excitons in quantum wells
We introduce a computationally efficient approach to calculating the
characteristics of excitons in quantum wells. In this approach we derive a
system of self-consistent equations describing the motion of an electron-hole
pair. The motion in the growth direction of the quantum well in this approach
is separated from the in-plane motion, but each of them occurs in modified
potentials found self-consistently. The approach is applied to shallow quantum
wells, for which we obtained an analytical expression for the exciton binding
energy and the ground state eigenfunction. Our results are in excellent
agreement with standard variational calculations, but require greatly reduced
computational effort.Comment: RevTeX4, 13 pages, 4 figures, submitted to Phys. Rev B Changed
content, added references, correct typo
A QCD motivated model for soft interactions at high energies
In this paper we develop an approach to soft scattering processes at high
energies,which is based on two mechanisms: Good-Walker mechanism for low mass
diffractionand multi-Pomeron interactions for high mass diffraction. The
pricipal idea, that allows us to specify the theory for Pomeron interactions,
is that the so called soft processes occur at rather short distances
(r^2 \propto 1 /^2 \propto \alpha'_\pom \approx 0.01 GeV^{-2}), where
perturbative QCD is valid. The value of the Pomeron slope \alpha'_\pom was
obtained from the fit to experimental data. Using this theoretical approach we
suggest a model that fits all soft data in the ISR-Tevatron energy range, the
total, elastic, single and double diffractive cross sections, including
dependence of the differential elastic cross section, and the mass dependence
of single diffraction. In this model we calculate the survival probability of
diffractive Higgs production, and obtained a value for this observable, which
is smaller than 1% at the LHC energy range.Comment: 33pp,20 figures in eps file
Effects of genuine dimension-six Higgs operators
We systematically discuss the consequences of genuine dimension-six Higgs
operators. These operators are not subject to stringent constraints from
electroweak precision data. However, they can modify the couplings of the Higgs
boson to electroweak gauge bosons and, in particular, the Higgs
self-interactions. We study the sensitivity to which those couplings can be
probed at future \ee linear colliders in the sub-TeV and in the multi-TeV
range. We find that for GeV with a luminosity of 1 ab the
anomalous and couplings may be probed to about the 0.01 level, and
the anomalous coupling to about the 0.1 level.Comment: 21 pages, 17 figures; typos corrected and references adde
Resonance- and Chaos-Assisted Tunneling
We consider dynamical tunneling between two symmetry-related regular islands
that are separated in phase space by a chaotic sea. Such tunneling processes
are dominantly governed by nonlinear resonances, which induce a coupling
mechanism between ``regular'' quantum states within and ``chaotic'' states
outside the islands. By means of a random matrix ansatz for the chaotic part of
the Hamiltonian, one can show that the corresponding coupling matrix element
directly determines the level splitting between the symmetric and the
antisymmetric eigenstates of the pair of islands. We show in detail how this
matrix element can be expressed in terms of elementary classical quantities
that are associated with the resonance. The validity of this theory is
demonstrated with the kicked Harper model.Comment: 25 pages, 5 figure
Thermodynamics and collapse of self-gravitating Brownian particles in D dimensions
We address the thermodynamics (equilibrium density profiles, phase diagram,
instability analysis...) and the collapse of a self-gravitating gas of Brownian
particles in D dimensions, in both canonical and microcanonical ensembles. In
the canonical ensemble, we derive the analytic form of the density scaling
profile which decays as f(x)=x^{-\alpha}, with alpha=2. In the microcanonical
ensemble, we show that f decays as f(x)=x^{-\alpha_{max}}, where \alpha_{max}
is a non-trivial exponent. We derive exact expansions for alpha_{max} and f in
the limit of large D. Finally, we solve the problem in D=2, which displays
rather rich and peculiar features
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