11,487 research outputs found
Electron Dynamics in Slowly Varying Antiferromagnetic Texture
Effective dynamics of conduction electrons in antiferromagnetic (AFM)
materials with slowly varying spin texture is developed via non-Abelian gauge
theory. Quite different from the ferromagnetic (FM) case, the spin of a
conduction electron does not follow the background texture even in the
adiabatic limit due to the accumulation of a SU(2) non-Abelian Berry phase.
Correspondingly, it is found that the orbital dynamics becomes spin-dependent
and is affected by two emergent gauge fields. While one of them is the
non-Abelian generalization of what has been discovered in FM systems, the other
leads to an anomalous velocity that has no FM counterpart. Two examples are
provided to illustrate the distinctive spin dynamics of a conduction electron.Comment: 4 pages, 3 figure
Spin pumping and spin-transfer torques in antiferromagnets
Spin pumping and spin-transfer torques are two reciprocal phenomena widely
studied in ferromagnetic materials. However, pumping from antiferromagnets and
its relation to current-induced torques have not been explored. By calculating
how electrons scatter off a normal metal-antiferromagnetic interface, we derive
pumped spin and staggered spin currents in terms of the staggered field, the
magnetization, and their rates of change. For both compensated and
uncompensated interfaces, spin pumping is of a similar magnitude as in
ferromagnets with a direction controlled by the polarization of the driving
microwave. The pumped currents are connected to current-induced torques via
Onsager reciprocity relations.Comment: 5 pages, 4 figure
Cross-Domain Labeled LDA for Cross-Domain Text Classification
Cross-domain text classification aims at building a classifier for a target
domain which leverages data from both source and target domain. One promising
idea is to minimize the feature distribution differences of the two domains.
Most existing studies explicitly minimize such differences by an exact
alignment mechanism (aligning features by one-to-one feature alignment,
projection matrix etc.). Such exact alignment, however, will restrict models'
learning ability and will further impair models' performance on classification
tasks when the semantic distributions of different domains are very different.
To address this problem, we propose a novel group alignment which aligns the
semantics at group level. In addition, to help the model learn better semantic
groups and semantics within these groups, we also propose a partial supervision
for model's learning in source domain. To this end, we embed the group
alignment and a partial supervision into a cross-domain topic model, and
propose a Cross-Domain Labeled LDA (CDL-LDA). On the standard 20Newsgroup and
Reuters dataset, extensive quantitative (classification, perplexity etc.) and
qualitative (topic detection) experiments are conducted to show the
effectiveness of the proposed group alignment and partial supervision.Comment: ICDM 201
AON: Towards Arbitrarily-Oriented Text Recognition
Recognizing text from natural images is a hot research topic in computer
vision due to its various applications. Despite the enduring research of
several decades on optical character recognition (OCR), recognizing texts from
natural images is still a challenging task. This is because scene texts are
often in irregular (e.g. curved, arbitrarily-oriented or seriously distorted)
arrangements, which have not yet been well addressed in the literature.
Existing methods on text recognition mainly work with regular (horizontal and
frontal) texts and cannot be trivially generalized to handle irregular texts.
In this paper, we develop the arbitrary orientation network (AON) to directly
capture the deep features of irregular texts, which are combined into an
attention-based decoder to generate character sequence. The whole network can
be trained end-to-end by using only images and word-level annotations.
Extensive experiments on various benchmarks, including the CUTE80,
SVT-Perspective, IIIT5k, SVT and ICDAR datasets, show that the proposed
AON-based method achieves the-state-of-the-art performance in irregular
datasets, and is comparable to major existing methods in regular datasets.Comment: Accepted by CVPR201
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