85,447 research outputs found
Two-loop triangle integrals with 4 scales for the vertex
We calculate analytically the two-loop triangle integrals entering the
corrections to the vertex with
using the method of differential equations. Our result
provides a prototype to study the analytic properties of multi-loop multi-scale
Feynman integrals, and also allows fast numeric evaluation for phenomenological
studies. We apply our results to the leptonic decay of the Higgs boson and to
production at electron-positron colliders. Besides the top quark loop, we
include also the bottom quark loop contributions, whose evaluation takes a lot
of time using purely numeric methods, but is very efficient with our analytic
results.Comment: 5 pages, 4 figure
Self-Assembly of Glycine on Cu (001): the Tales of Polarity and Temperature
Glycine on Cu(001) is used as an example to illustrate the critical role of
molecular polarity and finite temperature effect in self-assembly of
biomolecules at a metal surface. A unified picture for glycine self-assembly on
Cu(001) is derived based on full polarity compensation considerations,
implemented as a generic rule. Temperature plays a non-trivial role: the
ground-state structure at 0 K is absent at room temperature, where
intermolecular hydrogen bonding overweighs competing molecule-substrate
interactions. The unique p(2X4) structure from the rule is proved as the most
stable one by ab initio molecular dynamics at room temperature, and its STM
images and anisotropic free-electron-like dispersion are in excellent agreement
with experiments. Moreover, the rich self-assembling patterns including the
heterochiral and homochiral phases, and their interrelationships are entirely
governed by the same mechanism.Comment: 6 pages, 5 figure
Backward Compton Scattering and QED with Noncommutative Plane in the Strong Uniform Magnetic Field
In the strong uniform magnetic field, the noncommutative plane (NCP) caused
by the lowest Landau level (LLL) effect, and QED with NCP (QED-NCP) are
studied. Being similar to the condensed matter theory of quantum Hall effect,
an effective filling factor is introduced to character the possibility
that the electrons stay on the LLL. The analytic and numerical results of the
differential cross section for the process of backward Compton scattering in
the accelerator with unpolarized or polarized initial photons are calculated.
The existing data of BL38B2 in Spring-8 have been analyzed roughly and compared
with the numerical predictions primitively. We propose a precise measurement of
the differential cross sections of backward Compton scattering in a strong
perpendicular magnetic field, which may lead to reveal the effects of QED-NCP.Comment: 13 pages, 5 figure
Backward Compton Scattering in Strong Uniform Magnetic Field
In strong uniform magnetic field, the vacuum Non-Commutative Plane (NCP)
caused by the lowest Landau level(LLL) effect and the QED with NCP (QED-NCP)
are studied. Being similar to the theory of Quantum Hall effect, an effective
filling factor is introduced to character the possibility that the
electrons stays on LLL. The backward Compton scattering amplitudes of QED-NCP
are derived, and the differential cross sections for the process with polarized
initial electrons and photons are calculated. The existing Spring-8's data has
been analyzed primitively and some hints for QED-NCP effects are shown. We
propose to precisely measure the differential cross sections of the backward
Compton scattering in perpendicular magnetic field experimentally, which may
lead to reveal the effects of QED-NCP.
PACS number: 12.20.Ds; 11.10.Nx; 71.70.Di; 73.43.Fj.Comment: 13 pages, 8 figure
Bag-of-Words as Target for Neural Machine Translation
A sentence can be translated into more than one correct sentences. However,
most of the existing neural machine translation models only use one of the
correct translations as the targets, and the other correct sentences are
punished as the incorrect sentences in the training stage. Since most of the
correct translations for one sentence share the similar bag-of-words, it is
possible to distinguish the correct translations from the incorrect ones by the
bag-of-words. In this paper, we propose an approach that uses both the
sentences and the bag-of-words as targets in the training stage, in order to
encourage the model to generate the potentially correct sentences that are not
appeared in the training set. We evaluate our model on a Chinese-English
translation dataset, and experiments show our model outperforms the strong
baselines by the BLEU score of 4.55.Comment: accepted by ACL 201
Regularization: Convergence of Iterative Half Thresholding Algorithm
In recent studies on sparse modeling, the nonconvex regularization approaches
(particularly, regularization with ) have been demonstrated
to possess capability of gaining much benefit in sparsity-inducing and
efficiency. As compared with the convex regularization approaches (say,
regularization), however, the convergence issue of the corresponding algorithms
are more difficult to tackle. In this paper, we deal with this difficult issue
for a specific but typical nonconvex regularization scheme, the
regularization, which has been successfully used to many applications. More
specifically, we study the convergence of the iterative \textit{half}
thresholding algorithm (the \textit{half} algorithm for short), one of the most
efficient and important algorithms for solution to the
regularization. As the main result, we show that under certain conditions, the
\textit{half} algorithm converges to a local minimizer of the
regularization, with an eventually linear convergence rate. The established
result provides a theoretical guarantee for a wide range of applications of the
\textit{half} algorithm. We provide also a set of simulations to support the
correctness of theoretical assertions and compare the time efficiency of the
\textit{half} algorithm with other known typical algorithms for
regularization like the iteratively reweighted least squares (IRLS) algorithm
and the iteratively reweighted minimization (IRL1) algorithm.Comment: 12 pages, 5 figure
Reusing Wireless Power Transfer for Backscatter-assisted Cooperation in WPCN
This paper studies a novel user cooperation method in a wireless powered
communication network (WPCN), where a pair of closely located devices first
harvest wireless energy from an energy node (EN) and then use the harvested
energy to transmit information to an access point (AP). In particular, we
consider the two energy-harvesting users exchanging their messages and then
transmitting cooperatively to the AP using space-time block codes.
Interestingly, we exploit the short distance between the two users and allow
the information exchange to be achieved by energy-conserving backscatter
technique. Meanwhile the considered backscatter-assisted method can effectively
reuse wireless power transfer for simultaneous information exchange during the
energy harvesting phase. Specifically, we maximize the common throughput
through optimizing the time allocation on energy and information transmission.
Simulation results show that the proposed user cooperation scheme can
effectively improve the throughput fairness compared to some representative
benchmark methods.Comment: The paper has been accepted for publication in MLICOM 201
Accidental degeneracy and topological phase transitions in two-dimensional core-shell dielectric photonic crystals
A simple core-shell two-dimensional photonic crystal is studied where the
triangle lattice symmetry and rotation symmetry leads to rich physics
in the study of accidental degeneracy's in photonic bands. We systematically
evaluate different types of accidental nodal points, depending on the
dispersions around them and their topological properties, when the geometry and
permittivity are continuously changed. These accidental nodal points can be the
critical states lying between a topological phase and a normal phase and are
thus important for the study of topological photonic states. In time-reversal
systems, this leads to the photonic quantum spin Hall insulator where the spin
is defined upon the orbital angular momentum for transverse-magnetic
polarization. We study the topological phase transition as well as the
properties of the edge and bulk states and their application potentials in
optics
Rough extreme learning machine: a new classification method based on uncertainty measure
Extreme learning machine (ELM) is a new single hidden layer feedback neural
network. The weights of the input layer and the biases of neurons in hidden
layer are randomly generated, the weights of the output layer can be
analytically determined. ELM has been achieved good results for a large number
of classification tasks. In this paper, a new extreme learning machine called
rough extreme learning machine (RELM) was proposed. RELM uses rough set to
divide data into upper approximation set and lower approximation set, and the
two approximation sets are utilized to train upper approximation neurons and
lower approximation neurons. In addition, an attribute reduction is executed in
this algorithm to remove redundant attributes. The experimental results showed,
comparing with the comparison algorithms, RELM can get a better accuracy and
repeatability in most cases, RELM can not only maintain the advantages of fast
speed, but also effectively cope with the classification task for
high-dimensional data.Comment: 23 page
Multi-Label Robust Factorization Autoencoder and its Application in Predicting Drug-Drug Interactions
Drug-drug interactions (DDIs) are a major cause of preventable
hospitalizations and deaths. Predicting the occurrence of DDIs helps drug
safety professionals allocate investigative resources and take appropriate
regulatory action promptly. Traditional DDI prediction methods predict DDIs
based on the similarity between drugs. Recently, researchers revealed that
predictive performance can be improved by better modeling the interactions
between drug pairs with bilinear forms. However, the shallow models leveraging
bilinear forms suffer from limitations on capturing complicated nonlinear
interactions between drug pairs. To this end, we propose Multi-Label Robust
Factorization Autoencoder (abbreviated to MuLFA) for DDI prediction, which
learns a representation of interactions between drug pairs and has the
capability of characterizing complicated nonlinear interactions more precisely.
Moreover, a novel loss called CuXCov is designed to effectively learn the
parameters of MuLFA. Furthermore, the decoder is able to generate high-risk
chemical structures of drug pairs for specific DDIs, assisting pharmacists to
better understand the relationship between drug chemistry and DDI. Experimental
results on real-world datasets demonstrate that MuLFA consistently outperforms
state-of-the-art methods; particularly, it increases 21:3% predictive
performance compared to the best baseline for top 50 frequent DDIs.We also
illustrate various case studies to demonstrate the efficacy of the chemical
structures generated by MuLFA in DDI diagnosis
- …