40,021 research outputs found
Component-based Segmentation of words from handwritten Arabic text
Efficient preprocessing is very essential for automatic recognition of handwritten documents. In this paper, techniques on segmenting words in handwritten Arabic text are presented. Firstly, connected components (ccs) are extracted, and distances among different components are analyzed. The statistical distribution of this distance is then obtained to determine an optimal threshold for words segmentation. Meanwhile, an improved projection based method is also employed for baseline detection. The proposed method has been successfully tested on IFN/ENIT database consisting of 26459 Arabic words handwritten by 411 different writers, and the results were promising and very encouraging in more accurate detection of the baseline and segmentation of words for further recognition
The branch processes of vortex filaments and Hopf Invariant Constraint on Scroll Wave
In this paper, by making use of Duan's topological current theory, the
evolution of the vortex filaments in excitable media is discussed in detail.
The vortex filaments are found generating or annihilating at the limit points
and encountering, splitting, or merging at the bifurcation points of a complex
function . It is also shown that the Hopf invariant of knotted
scroll wave filaments is preserved in the branch processes (splitting, merging,
or encountering) during the evolution of these knotted scroll wave filaments.
Furthermore, it also revealed that the "exclusion principle" in some chemical
media is just the special case of the Hopf invariant constraint, and during the
branch processes the "exclusion principle" is also protected by topology.Comment: 9 pages, 5 figure
Solving Dirac equations on a 3D lattice with inverse Hamiltonian and spectral methods
A new method to solve the Dirac equation on a 3D lattice is proposed, in
which the variational collapse problem is avoided by the inverse Hamiltonian
method and the fermion doubling problem is avoided by performing spatial
derivatives in momentum space with the help of the discrete Fourier transform,
i.e., the spectral method. This method is demonstrated in solving the Dirac
equation for a given spherical potential in 3D lattice space. In comparison
with the results obtained by the shooting method, the differences in single
particle energy are smaller than ~MeV, and the densities are almost
identical, which demonstrates the high accuracy of the present method. The
results obtained by applying this method without any modification to solve the
Dirac equations for an axial deformed, non-axial deformed, and octupole
deformed potential are provided and discussed.Comment: 18 pages, 6 figure
Local and Nonlocal Contents in N-qubit generalized GHZ states
We investigate local contents in -qubit generalized Greenberger, Horne,
and Zeilinger (GHZ) states. We suggest a decomposition for correlations in the
GHZ states into a nonlocal and fully local part, and find a lower and upper
bound on the local content. Our lower bound reproduces the previous result for
N=2 [Scarani, Phys. Rev. A. 77, 042112 (2008)] and decreases rapidly with .Comment: 4 pages; 1 figure; figure regenerated; upper bound added; a few more
clarification
Topological Properties of Spatial Coherence Function
Topology of the spatial coherence function is considered in details. The
phase singularity (coherence vortices) structures of coherence function are
classified by Hopf index and Brouwer degree in topology. The coherence flux
quantization and the linking of the closed coherence vortices are also studied
from the topological properties of the spatial coherence function.Comment: 9 page
Structure of the regulatory domain of the LysR family regulator NMB2055 (MetR-like protein) from Neisseria meningitidis
Copyright @ 2012 International Union of CrystallographyThe crystal structure of the regulatory domain of NMB2055, a putative MetR regulator from Neisseria meningitidis, is reported at 2.5â
Ă
resolution. The structure revealed that there is a disulfide bond inside the predicted effector-binding pocket of the regulatory domain. Mutation of the cysteines (Cys103 and Cys106) that form the disulfide bond to serines resulted in significant changes to the structure of the effector pocket. Taken together with the high degree of conservation of these cysteine residues within MetR-related transcription factors, it is suggested that the Cys103 and Cys106 residues play an important role in the function of MetR regulators.This study is funded by the Medical
Research Council, with additional finance from the Biotechnology and Biological Science Research Council
Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory
We study the ground-state octet baryon masses and sigma terms using the
covariant baryon chiral perturbation theory (ChPT) with the
extended-on-mass-shell (EOMS) renormalization scheme up to
next-to-next-to-next-to-leading order (NLO). By adjusting the available 19
low-energy constants (LECs), a reasonable fit of the lattice quantum
chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and
NPLQCD collaborations is achieved. Finite-volume corrections to the lattice
data are calculated self-consistently. Our study shows that NLO BChPT
describes better the light quark mass evolution of the lattice data than the
NNLO BChPT does and the various lattice simulations seem to be consistent with
each other. We also predict the pion and strangeness sigma terms of the octet
baryons using the LECs determined in the fit of their masses. The predicted
pion- and strangeness-nucleon sigma terms are MeV and
MeV, respectively.Comment: 28 pages, 6 figures, minor revisions, typos corrected, version to
appear in JHE
- âŚ