51,557 research outputs found
Voices from the diaspora: changing hierarchies and dynamics of Chinese multilingualism
The so-called Chinese diasporas, i.e. Chinese communities outside Greater China (China, Hong Kong, Macau, and Taiwan), have traditionally been dialect dominant; that is, the vast majority of Chinese immigrants are speakers of (especially Southern) dialects. Cantonese and Hokkien are two of the most prominent dialects. With globalization and the rise of China as a world politico-economic power, the national, standardized variety, Putonghua, is gaining particular prestige amongst the Chinese diasporas. For example, all the Cantonese schools for British Chinese children in the UK now also teach Putonghua, but none of the Putonghua schools teach Cantonese. Using ethnographic interviews with and participant observation of Chinese people of different generations in various diasporic communities, this paper examines the changing hierarchies of varieties of Chinese, the implications of such changes for the education and identity development of the young, and the constitution of a (speech) community in the post-modern era. It focuses on language attitude and linguistic practices (including literacy practices). It also investigates the tensions between the competing ideologies and discourses on national and ethnic identities, nationalism, community relations and cultural values
Dynamical chiral symmetry breaking in QED at finite density and impurity potential
We study the effects of finite chemical potential and impurity scattering on
dynamical fermion mass generation in (2+1)-dimensional quantum electrodynamics.
In any realistic systems, these effects usually can not be neglected. The
longitudinal component of gauge field develops a finite static length produced
by chemical potential and impurity scattering, while the transverse component
remains long-ranged because of the gauge invariance. Another important
consequence of impurity scattering is that the fermions have a finite damping
rate, which reduces their lifetime staying in a definite quantum state. By
solving the Dyson-Schwinger equation for fermion mass function, it is found
that these effects lead to strong suppression of the critical fermion flavor
and the dynamical fermion mass in the symmetry broken phase.Comment: 8 pages, 4 figure
Person Re-Identification by Deep Joint Learning of Multi-Loss Classification
Existing person re-identification (re-id) methods rely mostly on either
localised or global feature representation alone. This ignores their joint
benefit and mutual complementary effects. In this work, we show the advantages
of jointly learning local and global features in a Convolutional Neural Network
(CNN) by aiming to discover correlated local and global features in different
context. Specifically, we formulate a method for joint learning of local and
global feature selection losses designed to optimise person re-id when using
only generic matching metrics such as the L2 distance. We design a novel CNN
architecture for Jointly Learning Multi-Loss (JLML) of local and global
discriminative feature optimisation subject concurrently to the same re-id
labelled information. Extensive comparative evaluations demonstrate the
advantages of this new JLML model for person re-id over a wide range of
state-of-the-art re-id methods on five benchmarks (VIPeR, GRID, CUHK01, CUHK03,
Market-1501).Comment: Accepted by IJCAI 201
First Order Sea Clutter Cross Section for HF Hybrid Sky-Surface Wave Radar
This paper presents a modified method to simulate the first order sea clutter cross section for high frequency (HF) hybrid sky-surface wave radar, based on the existent model applied in the bistatic HF surface wave radar. The modification focuses on the derivation of Bragg scattering frequency and the ionosphere dispersive impact on the clutter resolution cell. Meanwhile, an analytic expression to calculate the dispersive transfer function is derived on condition that the ionosphere is spherical stratified. Simulation results explicate the variance of the cross section after taking account of the influence triggered by the actual clutter resolution cell, and the spectral width of the first order sea clutter is defined so as to compare the difference. Eventually, experiment results are present to verify the rationality and validity of the proposed method
Feature Screening via Distance Correlation Learning
This paper is concerned with screening features in ultrahigh dimensional data
analysis, which has become increasingly important in diverse scientific fields.
We develop a sure independence screening procedure based on the distance
correlation (DC-SIS, for short). The DC-SIS can be implemented as easily as the
sure independence screening procedure based on the Pearson correlation (SIS,
for short) proposed by Fan and Lv (2008). However, the DC-SIS can significantly
improve the SIS. Fan and Lv (2008) established the sure screening property for
the SIS based on linear models, but the sure screening property is valid for
the DC-SIS under more general settings including linear models. Furthermore,
the implementation of the DC-SIS does not require model specification (e.g.,
linear model or generalized linear model) for responses or predictors. This is
a very appealing property in ultrahigh dimensional data analysis. Moreover, the
DC-SIS can be used directly to screen grouped predictor variables and for
multivariate response variables. We establish the sure screening property for
the DC-SIS, and conduct simulations to examine its finite sample performance.
Numerical comparison indicates that the DC-SIS performs much better than the
SIS in various models. We also illustrate the DC-SIS through a real data
example.Comment: 32 pages, 5 tables and 1 figure. Wei Zhong is the corresponding
autho
Interaction and excitonic insulating transition in graphene
The strong long-range Coulomb interaction between massless Dirac fermions in
graphene can drive a semimetal-insulator transition. We show that this
transition is strongly suppressed when the Coulomb interaction is screened by
such effects as disorder, thermal fluctuation, doping, and finite volume. It is
completely suppressed once the screening factor is beyond a threshold
even for infinitely strong coupling. However, such transition is
still possible if there is an additional strong contact four-fermion
interaction. The differences between screened and contact interactions are also
discussed.Comment: 7 pages, 4 figures, to appear in Phys. Rev.
Analytical result on the supercurrent through a superconductor/quantum-dot/superconductor junction
We present an analytical result for the supercurrent across a
superconductor/quantum-dot/superconductor junction. By converting the current
integration into a special contour integral, we can express the current as a
sum of the residues of poles. These poles are real and give a natural
definition of the Andreev bound states. We also use the exact result to explain
some features of the supercurrent transport behavior.Comment: 8 pages, 2 figure
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