3,340 research outputs found
Grouping Boundary Proposals for Fast Interactive Image Segmentation
Geodesic models are known as an efficient tool for solving various image
segmentation problems. Most of existing approaches only exploit local pointwise
image features to track geodesic paths for delineating the objective
boundaries. However, such a segmentation strategy cannot take into account the
connectivity of the image edge features, increasing the risk of shortcut
problem, especially in the case of complicated scenario. In this work, we
introduce a new image segmentation model based on the minimal geodesic
framework in conjunction with an adaptive cut-based circular optimal path
computation scheme and a graph-based boundary proposals grouping scheme.
Specifically, the adaptive cut can disconnect the image domain such that the
target contours are imposed to pass through this cut only once. The boundary
proposals are comprised of precomputed image edge segments, providing the
connectivity information for our segmentation model. These boundary proposals
are then incorporated into the proposed image segmentation model, such that the
target segmentation contours are made up of a set of selected boundary
proposals and the corresponding geodesic paths linking them. Experimental
results show that the proposed model indeed outperforms state-of-the-art
minimal paths-based image segmentation approaches
Geodesic Models with Convexity Shape Prior
The minimal geodesic models based on the Eikonal equations are capable of
finding suitable solutions in various image segmentation scenarios. Existing
geodesic-based segmentation approaches usually exploit image features in
conjunction with geometric regularization terms, such as Euclidean curve length
or curvature-penalized length, for computing geodesic curves. In this paper, we
take into account a more complicated problem: finding curvature-penalized
geodesic paths with a convexity shape prior. We establish new geodesic models
relying on the strategy of orientation-lifting, by which a planar curve can be
mapped to an high-dimensional orientation-dependent space. The convexity shape
prior serves as a constraint for the construction of local geodesic metrics
encoding a particular curvature constraint. Then the geodesic distances and the
corresponding closed geodesic paths in the orientation-lifted space can be
efficiently computed through state-of-the-art Hamiltonian fast marching method.
In addition, we apply the proposed geodesic models to the active contours,
leading to efficient interactive image segmentation algorithms that preserve
the advantages of convexity shape prior and curvature penalization.Comment: This paper has been accepted by TPAM
A unique distant submillimeter galaxy with an X-ray-obscured radio-luminous active galactic nucleus
We present a multiwavelength study of an atypical submillimeter galaxy in the
GOODS-North field, with the aim to understand its physical properties of
stellar and dust emission, as well as the central AGN activity. Although it is
shown that the source is likely an extremely dusty galaxy at high redshift, its
exact position of submillimeter emission is unknown. With the new NOEMA
interferometric imaging, we confirm that the source is a unique dusty galaxy.
It has no obvious counterpart in the optical and even NIR images observed with
HST at lambda~<1.4um. Photometric-redshift analyses from both stellar and dust
SED suggest it to likely be at z~>4, though a lower redshift at z~>3.1 cannot
be fully ruled out (at 90% confidence interval). Explaining its unusual
optical-to-NIR properties requires an old stellar population (~0.67 Gyr),
coexisting with a very dusty ongoing starburst component. The latter is
contributing to the FIR emission, with its rest-frame UV and optical light
being largely obscured along our line of sight. If the observed fluxes at the
rest-frame optical/NIR wavelengths were mainly contributed by old stars, a
total stellar mass of ~3.5x10^11Msun would be obtained. An X-ray spectral
analysis suggests that this galaxy harbors a heavily obscured AGN with
N_H=3.3x10^23 cm^-2 and an intrinsic 2-10 keV luminosity of L_X~2.6x10^44
erg/s, which places this object among distant type 2 quasars. The radio
emission of the source is extremely bright, which is an order of magnitude
higher than the star-formation-powered emission, making it one of the most
distant radio-luminous dusty galaxies. The combined characteristics of the
galaxy suggest that the source appears to have been caught in a rare but
critical transition stage in the evolution of submillimeter galaxies, where we
are witnessing the birth of a young AGN and possibly the earliest stage of its
jet formation and feedback.Comment: 13 pages in printer format, 10 figures, 1 table, accepted for
publication in the A&
Characterizing random-singlet state in two-dimensional frustrated quantum magnets and implications for the double perovskite SrCuTeWO
Motivated by experimental observation of the non-magnetic phase in the
compounds with frustration and disorder, we study the ground state of the
spin- square-lattice Heisenberg model with randomly distributed
nearest-neighbor and next-nearest-neighbor couplings. By using the
density matrix renormalization group (DMRG) calculation on cylinder system with
circumference up to lattice sites, we identify a disordered phase between
the N\'eel and stripe magnetic phase with growing in the presence
of strong randomness. The vanished spin-freezing parameter indicates the absent
spin glass order. The large-scale DMRG results unveil the size-scaling
behaviors of the spin-freezing parameter, the power-law decay of average spin
correlation, and the exponential decay of typical spin correlation, which all
agree with the corresponding behavior in the one-dimensional random singlet
(RS) state and characterize the RS nature of this non-magnetic state. The DMRG
simulation also opens new insight and opportunities for characterizing a class
of non-magnetic states in two-dimensional frustrated magnets with disorder. We
also compare with existing experiments and suggest more measurements for
understanding the spin-liquid-like behavior in the double perovskite
SrCuTeWO.Comment: 11 pages,10 figure
A Region-based Randers Geodesic Approach for Image Segmentation
The minimal path model based on the Eikonal partial differential equation has
served as a fundamental tool for the applications of image segmentation and
boundary detection in the passed two decades. However, the existing approaches
commonly only exploit the image edge-based features for computing minimal
paths, potentially limiting their performance in complicated segmentation
situations. In this paper, we introduce a new variational image segmentation
model based on the minimal path framework and the eikonal PDE, where the
region-based appearance term that defines then regional homogeneity features
can be taken into account for estimating the associated minimal paths. This is
done by constructing a Randers geodesic metric interpretation to the
region-based active contour energy. As a result, the minimization of the active
contour energy is transformed to finding the solution to the Randers eikonal
PDE.
We also suggest a practical interactive image segmentation strategy, where
the target boundary can be delineated by the concatenation of the piecewise
geodesic paths. We invoke the Finsler variant of the fast marching method to
estimate the geodesic distance map, yielding an efficient implementation of the
proposed Eikonal region-based active contour model. Experimental results on
both synthetic and real images exhibit that our model indeed achieves
encouraging segmentation performance
Radon and childhood cancer
British Journal of Cancer (2002) 87, 1336–1337. doi:10.1038/sj.bjc.6600671 www.bjcancer.co
Confront Holographic QCD with Regge Trajectories of vectors and axial-vectors
We derive the general 5-dimension metric structure of the system in
type II superstring theory, and demonstrate the physical meaning of the
parameters characterizing the 5-dimension metric structure of the
\textit{holographic} QCD model by relating them to the parameters describing
Regge trajectories. By matching the spectra of vector mesons with
deformed soft-wall model, we find that the spectra of vector mesons
can be described very well in the soft-wall model, i.e,
soft-wall model. We then investigate how well the soft-wall
model can describe the Regge trajectory of axial-vector mesons . We find
that the constant component of the 5-dimension mass square of axial-vector
mesons plays an efficient role to realize the chiral symmetry breaking in the
vacuum, and a small negative correction in the 5-dimension mass square is
helpful to realize the chiral symmetry restoration in high excitation states.Comment: 9 pages, 3 figure and 3 tables, one section adde
Rare B decays and Tevatron top-pair asymmetry
The recent Tevatron result on the top quark forward-backward asymmetry, which
deviates from its standard model prediction by 3.4, has prompted many
authors to build new models to account for this anomaly. Among the various
proposals, we find that those mechanisms which produce via - or
-channel can have a strong correlation to the rare B decays. We demonstrate
this link by studying a model with a new charged gauge boson, . In terms of
the current measurements on decays, we conclude that the branching
ratio for is affected most by the new effects.
Furthermore, using the world average branching ratio for the exclusive B decays
at level, we discuss the allowed values for the new parameters.
Finally, we point out that the influence of the new physics effects on the
direct CP asymmetry in B decays is insignificant.Comment: 15 page, 6 figures, typos corrected and references added, final
version to appear journa
Thermodynamics of deformed AdS model with a positive/negative quadratic correction in graviton-dilaton system
By solving the Einstein equations of the graviton coupling with a real scalar
dilaton field, we establish a general framework to self-consistently solve the
geometric background with black-hole for any given phenomenological holographic
models. In this framwork, we solve the black-hole background, the corresponding
dilaon field and the dilaton potential for the deformed AdS model with a
positive/negative quadratic correction. We systematically investigate the
thermodynamical properties of the deformed AdS model with a positive and
negative quadratic correction, respectively, and compare with lattice QCD on
the results of the equation of state, the heavy quark potential, the Polyakov
loop and the spatial Wilson loop. We find that the bulk thermodynamical
properties are not sensitive to the sign of the quadratic correction, and the
results of both deformed holographic QCD models agree well with lattice QCD
result for pure SU(3) gauge theory. However, the results from loop operators
favor a positive quadratic correction, which agree well with lattice QCD
result. Especially, the result from the Polyakov loop excludes the model with a
negative quadratic correction in the warp factor of .Comment: 26 figures,36 pages,V.3: an appendix,more equations and references
added,figures corrected,published versio
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