298 research outputs found
Neural Collective Entity Linking
Entity Linking aims to link entity mentions in texts to knowledge bases, and
neural models have achieved recent success in this task. However, most existing
methods rely on local contexts to resolve entities independently, which may
usually fail due to the data sparsity of local information. To address this
issue, we propose a novel neural model for collective entity linking, named as
NCEL. NCEL applies Graph Convolutional Network to integrate both local
contextual features and global coherence information for entity linking. To
improve the computation efficiency, we approximately perform graph convolution
on a subgraph of adjacent entity mentions instead of those in the entire text.
We further introduce an attention scheme to improve the robustness of NCEL to
data noise and train the model on Wikipedia hyperlinks to avoid overfitting and
domain bias. In experiments, we evaluate NCEL on five publicly available
datasets to verify the linking performance as well as generalization ability.
We also conduct an extensive analysis of time complexity, the impact of key
modules, and qualitative results, which demonstrate the effectiveness and
efficiency of our proposed method.Comment: 12 pages, 3 figures, COLING201
Chandra Detection of Intra-cluster X-ray sources in Virgo
We present a survey of X-ray point sources in the nearest and dynamically
young galaxy cluster, Virgo, using archival Chandra observations that sample
the vicinity of 80 early-type member galaxies. The X-ray source populations at
the outskirt of these galaxies are of particular interest. We detect a total of
1046 point sources (excluding galactic nuclei) out to a projected
galactocentric radius of 40 kpc and down to a limiting 0.5-8 keV
luminosity of . Based on the cumulative
spatial and flux distributions of these sources, we statistically identify
120 excess sources that are not associated with the main stellar content
of the individual galaxies, nor with the cosmic X-ray background. This excess
is significant at a 3.5 level, when Poisson error and cosmic variance
are taken into account. On the other hand, no significant excess sources are
found at the outskirt of a control sample of field galaxies, suggesting that at
least some fraction of the excess sources around the Virgo galaxies are truly
intra-cluster X-ray sources. Assisted with ground-based and HST optical imaging
of Virgo, we discuss the origins of these intra-cluster X-ray sources, in terms
of supernova-kicked low-mass X-ray binaries (LMXBs), globular clusters, LMXBs
associated with the diffuse intra-cluster light, stripped nucleated dwarf
galaxies and free-floating massive black holes.Comment: 29 pages, 8 figures. Accepted for publication in ApJ. Comments
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Joint Representation Learning of Cross-lingual Words and Entities via Attentive Distant Supervision
Joint representation learning of words and entities benefits many NLP tasks,
but has not been well explored in cross-lingual settings. In this paper, we
propose a novel method for joint representation learning of cross-lingual words
and entities. It captures mutually complementary knowledge, and enables
cross-lingual inferences among knowledge bases and texts. Our method does not
require parallel corpora, and automatically generates comparable data via
distant supervision using multi-lingual knowledge bases. We utilize two types
of regularizers to align cross-lingual words and entities, and design knowledge
attention and cross-lingual attention to further reduce noises. We conducted a
series of experiments on three tasks: word translation, entity relatedness, and
cross-lingual entity linking. The results, both qualitatively and
quantitatively, demonstrate the significance of our method.Comment: 11 pages, EMNLP201
Deciphering Charging Status, Absolute Quantum Efficiency, and Absorption Cross Section of MultiCarrier States in Single Colloidal Quantum Dot
Upon photo- or electrical-excitation, colloidal quantum dots (QDs) are often
found in multi-carrier states due to multi-photon absorption and photo-charging
of the QDs. While many of these multi-carrier states are observed in single-dot
spectroscopy, their properties are not well studied due to random
charging/discharging, emission intensity intermittency, and uncontrolled
surface defects of single QD. Here we report in-situ deciphering the charging
status, and precisely assessing the absorption cross section, and determining
the absolute emission quantum yield of mono-exciton and biexciton states for
neutral, positively-charged, and negatively-charged single core/shell CdSe/CdS
QD. We uncover very different photon statistics of the three charge states in
single QD and unambiguously identify their charge sign together with the
information of their photoluminescence decay dynamics. We then show their
distinct photoluminescence saturation behaviors and evaluated the absolute
values of absorption cross sections and quantum efficiencies of monoexcitons
and biexcitons. We demonstrate that addition of an extra hole or electron in a
QD changes not only its emission properties but also varies its absorption
cross section
Combat COVID-19 with artificial intelligence and big data.
To combat COVID-19, at least 29 countries/regions have resorted to digital technology; some embedded it with strict containment measures and achieved great success. We need to improve cryptography and regulations that would enable contact-tracing systems without mass surveillance in order to attain the benefits of location-tracking while protecting individual privacy.</jats:p
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