3,760 research outputs found
Searching and organizing images across languages
With the continual growth of users on the Web
from a wide range of countries, supporting
such users in their search of cultural heritage
collections will grow in importance. In the
next few years, the growth areas of Internet
users will come from the Indian sub-continent
and China. Consequently, if holders of cultural
heritage collections wish their content to be
viewable by the full range of users coming to
the Internet, the range of languages that they
need to support will have to grow. This paper
will present recent work conducted at the
University of Sheffield (and now being
implemented in BRICKS) on how to use
automatic translation to provide search and
organisation facilities for a historical image
search engine. The system allows users to
search for images in seven different languages,
providing means for the user to examine
translated image captions and browse retrieved
images organised by categories written in their
native language
Harmonic coordinates in the string and membrane equations
In this note, we first show that the solutions to Cauchy problems for two
versions of relativistic string and membrane equations are diffeomorphic. Then
we investigate the coordinates transformation presented in Ref. [9] (see (2.20)
in Ref. [9]) which plays an important role in the study on the dynamics of the
motion of string in Minkowski space. This kind of transformed coordinates are
harmonic coordinates, and the nonlinear relativistic string equations can be
straightforwardly simplified into linear wave equations under this
transformation
One-side forward-backward asymmetry at the LHC
Forward-backward asymmetry is an essential observable to study
the nature of coupling in the standard model and physics beyond the standard
model, as shown at LEP and Tevatron. As a proton-proton collider, the LHC does
not have the preferred direction contrary to her counterpart, namely, LEP and
Tevatron. Therefore is not applicable at the LHC. However for the
proton the momentum of valence quark is usually larger than that of the sea
quark. Utilizing this feature we have defined a so-called one-side
forward-backward asymmetry for the top quark pair production at
LHC in the previous work. In this paper we extend our studies to the charged
leptons and bottom quarks as the final states. Our numerical results show that
at the LHC can be utilized to study the nature of the couplings
once enough events are collected.Comment: 19 pages, 7 figures, 1 table, published versio
Quasiparticle Interference on the Surface of the Topological Insulator BiTe
The quasiparticle interference of the spectroscopic imaging scanning
tunneling microscopy has been investigated for the surface states of the large
gap topological insulator BiTe through the T-matrix formalism. Both the
scalar potential scattering and the spin-orbit scattering on the warped
hexagonal isoenergy contour are considered. While backscatterings are forbidden
by time-reversal symmetry, other scatterings are allowed and exhibit strong
dependence on the spin configurations of the eigenfunctions at k points over
the isoenergy contour. The characteristic scattering wavevectors found in our
analysis agree well with recent experiment results.Comment: 5 pages, 2 figures, Some typos are correcte
Plaquette Ordered Phase and Quantum Phase Diagram in the Spin-1/2 J1-J2 Square Heisenberg Model
We study the spin-1/2 Heisenberg model on the square lattice with first- and
second-neighbor antiferromagnetic interactions J1 and J2, which possesses a
nonmagnetic region that has been debated for many years and might realize the
interesting Z2 spin liquid. We use the density matrix renormalization group
approach with explicit implementation of SU(2) spin rotation symmetry and study
the model accurately on open cylinders with different boundary conditions. With
increasing J2, we find a Neel phase, a plaquette valence-bond (PVB) phase with
a finite spin gap, and a possible spin liquid in a small region of J2 between
these two phases. From the finite-size scaling of the magnetic order parameter,
we estimate that the Neel order vanishes at J2/J1~0.44. For 0.5<J2/J1<0.61, we
find dimer correlations and PVB textures whose decay lengths grow strongly with
increasing system width, consistent with a long-range PVB order in the
two-dimensional limit. The dimer-dimer correlations reveal the s-wave character
of the PVB order. For 0.44<J2/J1<0.5, spin order, dimer order, and spin gap are
small on finite-size systems and appear to scale to zero with increasing system
width, which is consistent with a possible gapless SL or a near-critical
behavior. We compare and contrast our results with earlier numerical studies.Comment: 11 pages, 17 figures, and 1 tabl
A Weighted Moving Average Process for Forecasting
The object of the present study is to propose a forecasting model for a nonstationary stochastic realization. The subject model is based on modifying a given time series into a new k-time moving average time series to begin the development of the model. The study is based on the autoregressive integrated moving average process along with its analytical constrains. The analytical procedure of the proposed model is given. A stock XYZ selected from the Fortune 500 list of companies and its daily closing price constitute the time series. Both the classical and proposed forecasting models were developed and a comparison of the accuracy of their responses is given
A Weighted Moving Average Process for Forcasting
A forecasting model for a nonstationary stochastic realization is proposed based on modifying a given time series into a new k-time moving average time series. The study is based on the autoregressive integrated moving average process along with its analytical constrains. The analytical procedure of the proposed model is given. A stock XYZ selected from the Fortune 500 list of companies and its daily closing price constitute the time series. Both the classical and proposed forecasting models were developed and a comparison of the accuracy of their responses is given
SO(5) Superconductors in a Zeeman Magnetic Field
The generic symmetry of a system under a uniform Zeeman magnetic field is
U(1) x U(1). However, we show that SO(5) models in the presence of a finite
chemical potential and a finite Zeeman magnetic field can have a exact SU(2) x
U(1) symmetry. This principle can be used to test SO(5) symmetry at any doping
level
Nondiffusive spin dynamics in a two-dimensional electron gas
We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs=GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wave vector range from zero to 6 x 104 cm-1. We find that the spin polarization lifetime is maximal at a nonzero wave vector, in contrast with expectations based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit couplin
- …