53,652 research outputs found
Quark Orbital Angular Momentum in the Baryon
Analytical and numerical results, for the orbital and spin content carried by
different quark flavors in the baryons, are given in the chiral quark model
with symmetry breaking. The reduction of the quark spin, due to the spin
dilution in the chiral splitting processes, is transferred into the orbital
motion of quarks and antiquarks. The orbital angular momentum for each quark
flavor in the proton as a function of the partition factor and the
chiral splitting probability is shown. The cancellation between the spin
and orbital contributions in the spin sum rule and in the baryon magnetic
moments is discussed.Comment: 26 pages, 3 figures, revised version with minor eq. no and ref. no.
corrections. Discussion on the spin and a new ref. are adde
Deep Discrete Hashing with Self-supervised Pairwise Labels
Hashing methods have been widely used for applications of large-scale image
retrieval and classification. Non-deep hashing methods using handcrafted
features have been significantly outperformed by deep hashing methods due to
their better feature representation and end-to-end learning framework. However,
the most striking successes in deep hashing have mostly involved discriminative
models, which require labels. In this paper, we propose a novel unsupervised
deep hashing method, named Deep Discrete Hashing (DDH), for large-scale image
retrieval and classification. In the proposed framework, we address two main
problems: 1) how to directly learn discrete binary codes? 2) how to equip the
binary representation with the ability of accurate image retrieval and
classification in an unsupervised way? We resolve these problems by introducing
an intermediate variable and a loss function steering the learning process,
which is based on the neighborhood structure in the original space.
Experimental results on standard datasets (CIFAR-10, NUS-WIDE, and Oxford-17)
demonstrate that our DDH significantly outperforms existing hashing methods by
large margin in terms of~mAP for image retrieval and object recognition. Code
is available at \url{https://github.com/htconquer/ddh}
A covariant entropy conjecture on cosmological dynamical horizon
We here propose a covariant entropy conjecture on cosmological dynamical
horizon. After the formulation of our conjecture, we test its validity in
adiabatically expanding universes with open, flat and closed spatial geometry,
where our conjecture can also be viewed as a cosmological version of the
generalized second law of thermodynamics in some sense.Comment: JHEP style, 9 pages, 1 figure, typos corrected, accepted for
publication in JHE
First-principles calculations of the self-trapped exciton in crystalline NaCl
The atomic and electronic structure of the lowest triplet state of the
off-center (C2v symmetry) self-trapped exciton (STE) in crystalline NaCl is
calculated using the local-spin-density (LSDA) approximation. In addition, the
Franck-Condon broadening of the luminescence peak and the a1g -> b3u absorption
peak are calculated and compared to experiment. LSDA accurately predicts
transition energies if the initial and final states are both localized or
delocalized, but 1 eV discrepancies with experiment occur if one state is
localized and the other is delocalized.Comment: 4 pages with 4 embeddded figure
Estimating Depth from RGB and Sparse Sensing
We present a deep model that can accurately produce dense depth maps given an
RGB image with known depth at a very sparse set of pixels. The model works
simultaneously for both indoor/outdoor scenes and produces state-of-the-art
dense depth maps at nearly real-time speeds on both the NYUv2 and KITTI
datasets. We surpass the state-of-the-art for monocular depth estimation even
with depth values for only 1 out of every ~10000 image pixels, and we
outperform other sparse-to-dense depth methods at all sparsity levels. With
depth values for 1/256 of the image pixels, we achieve a mean absolute error of
less than 1% of actual depth on indoor scenes, comparable to the performance of
consumer-grade depth sensor hardware. Our experiments demonstrate that it would
indeed be possible to efficiently transform sparse depth measurements obtained
using e.g. lower-power depth sensors or SLAM systems into high-quality dense
depth maps.Comment: European Conference on Computer Vision (ECCV) 2018. Updated to
camera-ready version with additional experiment
Covariant entropy conjecture and concordance cosmological models
Recently a covariant entropy conjecture has been proposed for dynamical
horizons. We apply this conjecture to concordance cosmological models, namely,
those cosmological models filled with perfect fluids, in the presence of a
positive cosmological constant. As a result, we find this conjecture has a
severe constraint power. Not only does this conjecture rule out those
cosmological models disfavored by the anthropic principle, but also it imposes
an upper bound on the cosmological constant for our own universe,
which thus provides an alternative macroscopic perspective for understanding
the long-standing cosmological constant problem.Comment: 10 pages, 1 figure, JHEP style, references added, published versio
Properties of vector mesons at finite temperature -effective lagrangian approach-
The properties of -mesons at finite temperature () are examined with
an effective chiral lagrangian in which vector and axial-vector mesons are
included as massive Yang-Mills fields of the chiral symmetry. It is shown that,
at order, the effective mass is not changed but only the mixing effect in
vector and axial-vector correlator appears.Comment: 13 pages (REVTeX), two figures
The Far-Infrared Background Correlation with CMB Lensing
The intervening large--scale structure distorts cosmic microwave background
(CMB) anisotropies via gravitational lensing. The same large--scale structure,
traced by dusty star--forming galaxies, also induces anisotropies in the
far--infrared background (FIRB). We investigate the resulting inter--dependence
of the FIRB and CMB with a halo model for the FIRB. In particular, we calculate
the cross--correlation between the lensing potential and the FIRB. The lensing
potential can be quadratically estimated from CMB temperature and/or
polarization maps. We show that the cross--correlation can be measured with
high signal--to--noise with data from the Planck Surveyor. We discuss how such
a measurement can be used to understand the nature of FIRB sources and their
relation to the distribution of dark matter.Comment: 9 pages, 5 figures, submitted to Ap
An analysis of the acoustic cavitation noise spectrum: The role of periodic shock waves
Research on applications of acoustic cavitation is often reported in terms of the features within the spectrum of the emissions gathered during cavitation occurrence. There is, however, limited understanding as to the contribution of specific bubble activity to spectral features, beyond a binary interpretation of stable versus inertial cavitation. In this work, laser-nucleation is used to initiate cavitation within a few millimeters of the tip of a needle hydrophone, calibrated for magnitude and phase from 125 kHz to 20 MHz. The bubble activity, acoustically driven at f0â=â692 kHz, is resolved with high-speed shadowgraphic imaging at 5âĂâ106 frames per second. A synthetic spectrum is constructed from component signals based on the hydrophone data, deconvolved within the calibration bandwidth, in the time domain. Cross correlation coefficients between the experimental and synthetic spectra of 0.97 for the f 0/2 and f 0/3 regimes indicate that periodic shock waves and scattered driving field predominantly account for all spectral features, including the sub-harmonics and their over-harmonics, and harmonics of f 0
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