23,823 research outputs found
Efficient Semidefinite Spectral Clustering via Lagrange Duality
We propose an efficient approach to semidefinite spectral clustering (SSC),
which addresses the Frobenius normalization with the positive semidefinite
(p.s.d.) constraint for spectral clustering. Compared with the original
Frobenius norm approximation based algorithm, the proposed algorithm can more
accurately find the closest doubly stochastic approximation to the affinity
matrix by considering the p.s.d. constraint. In this paper, SSC is formulated
as a semidefinite programming (SDP) problem. In order to solve the high
computational complexity of SDP, we present a dual algorithm based on the
Lagrange dual formalization. Two versions of the proposed algorithm are
proffered: one with less memory usage and the other with faster convergence
rate. The proposed algorithm has much lower time complexity than that of the
standard interior-point based SDP solvers. Experimental results on both UCI
data sets and real-world image data sets demonstrate that 1) compared with the
state-of-the-art spectral clustering methods, the proposed algorithm achieves
better clustering performance; and 2) our algorithm is much more efficient and
can solve larger-scale SSC problems than those standard interior-point SDP
solvers.Comment: 13 page
Multi-stage Multi-recursive-input Fully Convolutional Networks for Neuronal Boundary Detection
In the field of connectomics, neuroscientists seek to identify cortical
connectivity comprehensively. Neuronal boundary detection from the Electron
Microscopy (EM) images is often done to assist the automatic reconstruction of
neuronal circuit. But the segmentation of EM images is a challenging problem,
as it requires the detector to be able to detect both filament-like thin and
blob-like thick membrane, while suppressing the ambiguous intracellular
structure. In this paper, we propose multi-stage multi-recursive-input fully
convolutional networks to address this problem. The multiple recursive inputs
for one stage, i.e., the multiple side outputs with different receptive field
sizes learned from the lower stage, provide multi-scale contextual boundary
information for the consecutive learning. This design is
biologically-plausible, as it likes a human visual system to compare different
possible segmentation solutions to address the ambiguous boundary issue. Our
multi-stage networks are trained end-to-end. It achieves promising results on
two public available EM segmentation datasets, the mouse piriform cortex
dataset and the ISBI 2012 EM dataset.Comment: Accepted by ICCV201
Bosonization of quantum sine-Gordon field with a boundary
Boundary operators and boundary ground states in sine-Gordon model with a
fixed boundary condition are studied using bosonization and q-deformed
oscillators.We also obtain the form-factors of this model.Comment: Latex 25page
Person Re-identification with Correspondence Structure Learning
This paper addresses the problem of handling spatial misalignments due to
camera-view changes or human-pose variations in person re-identification. We
first introduce a boosting-based approach to learn a correspondence structure
which indicates the patch-wise matching probabilities between images from a
target camera pair. The learned correspondence structure can not only capture
the spatial correspondence pattern between cameras but also handle the
viewpoint or human-pose variation in individual images. We further introduce a
global-based matching process. It integrates a global matching constraint over
the learned correspondence structure to exclude cross-view misalignments during
the image patch matching process, hence achieving a more reliable matching
score between images. Experimental results on various datasets demonstrate the
effectiveness of our approach
Perturbative corrections to form factors in QCD
We compute perturbative QCD corrections to form factors at leading
power in , at large hadronic recoil, from the light-cone sum rules
(LCSR) with -meson distribution amplitudes in HQET. QCD factorization for
the vacuum-to--meson correlation function with an interpolating current for
the -meson is demonstrated explicitly at one loop with the power counting
scheme . The jet
functions encoding information of the hard-collinear dynamics in the
above-mentioned correlation function are complicated by the appearance of an
additional hard-collinear scale , compared to the counterparts entering
the factorization formula of the vacuum-to--meson correction function for
the construction of from factors. Inspecting the
next-to-leading-logarithmic sum rules for the form factors of indicates that perturbative corrections to the hard-collinear functions
are more profound than that for the hard functions, with the default theory
inputs, in the physical kinematic region. We further compute the subleading
power correction induced by the three-particle quark-gluon distribution
amplitudes of the -meson at tree level employing the background gluon field
approach. The LCSR predictions for the semileptonic form
factors are then extrapolated to the entire kinematic region with the
-series parametrization. Phenomenological implications of our determinations
for the form factors are explored by investigating the
(differential) branching fractions and the ratio of
and by determining the CKM matrix element from the total decay rate
of .Comment: 49 pages, 8 figures, version accepted for publication in JHE
QCD calculations of form factors with higher-twist corrections
We update QCD calculations of form factors at large hadronic
recoil by including the subleading-power corrections from the higher-twist
-meson light-cone distribution amplitudes (LCDAs) up to the twist-six
accuracy and the strange-quark mass effects at leading-power in
from the twist-two -meson LCDA . The higher-twist
corrections from both the two-particle and three-particle -meson LCDAs are
computed from the light-cone QCD sum rules (LCSR) at tree level. In particular,
we construct the local duality model for the twist-five and -six -meson
LCDAs, in agreement with the corresponding asymptotic behaviours at small quark
and gluon momenta, employing the QCD sum rules in heavy quark effective theory
at leading order in . The strange quark mass effects in semileptonic
form factors yield the leading-power contribution in the heavy quark
expansion, consistent with the power-counting analysis in soft-collinear
effective theory, and they are also computed from the LCSR approach due to the
appearance of the rapidity singularities. We further explore the
phenomenological aspects of the semileptonic decays and
the rare exclusive processes , including the determination of
the CKM matrix element , the normalized differential
distributions and precision observables defined by the ratios of branching
fractions for the above-mentioned two channels in the same intervals of .Comment: 36 pages, 9 figure
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