2,179 research outputs found
Word Embeddings for Entity-annotated Texts
Learned vector representations of words are useful tools for many information
retrieval and natural language processing tasks due to their ability to capture
lexical semantics. However, while many such tasks involve or even rely on named
entities as central components, popular word embedding models have so far
failed to include entities as first-class citizens. While it seems intuitive
that annotating named entities in the training corpus should result in more
intelligent word features for downstream tasks, performance issues arise when
popular embedding approaches are naively applied to entity annotated corpora.
Not only are the resulting entity embeddings less useful than expected, but one
also finds that the performance of the non-entity word embeddings degrades in
comparison to those trained on the raw, unannotated corpus. In this paper, we
investigate approaches to jointly train word and entity embeddings on a large
corpus with automatically annotated and linked entities. We discuss two
distinct approaches to the generation of such embeddings, namely the training
of state-of-the-art embeddings on raw-text and annotated versions of the
corpus, as well as node embeddings of a co-occurrence graph representation of
the annotated corpus. We compare the performance of annotated embeddings and
classical word embeddings on a variety of word similarity, analogy, and
clustering evaluation tasks, and investigate their performance in
entity-specific tasks. Our findings show that it takes more than training
popular word embedding models on an annotated corpus to create entity
embeddings with acceptable performance on common test cases. Based on these
results, we discuss how and when node embeddings of the co-occurrence graph
representation of the text can restore the performance.Comment: This paper is accepted in 41st European Conference on Information
Retrieva
Tadpole renormalization and relativistic corrections in lattice NRQCD
We make a comparison of two tadpole renormalization schemes in the context of
the quarkonium hyperfine splittings in lattice NRQCD. Improved gauge-field and
NRQCD actions are analyzed using the mean-link in Landau gauge, and
using the fourth root of the average plaquette . Simulations are done
for , , and systems. The hyperfine splittings are
computed both at leading and at next-to-leading order in the relativistic
expansion. Results are obtained at lattice spacings in the range of about
0.14~fm to 0.38~fm. A number of features emerge, all of which favor tadpole
renormalization using . This includes much better scaling behavior of
the hyperfine splittings in the three quarkonium systems when is
used. We also find that relativistic corrections to the spin splittings are
smaller when is used, particularly for the and
systems. We also see signs of a breakdown in the NRQCD expansion when the bare
quark mass falls below about one in lattice units. Simulations with
also appear to be better behaved in this context: the bare quark masses turn
out to be larger when is used, compared to when is used on
lattices with comparable spacings. These results also demonstrate the need to
go beyond tree-level tadpole improvement for precision simulations.Comment: 14 pages, 7 figures (minor changes to some phraseology and
references
Analysis of a Large Sample of Neutrino-Induced Muons with the ArgoNeuT Detector
ArgoNeuT, or Argon Neutrino Test, is a 170 liter liquid argon time projection
chamber designed to collect neutrino interactions from the NuMI beam at Fermi
National Accelerator Laboratory. ArgoNeuT operated in the NuMI low-energy beam
line directly upstream of the MINOS Near Detector from September 2009 to
February 2010, during which thousands of neutrino and antineutrino events were
collected. The MINOS Near Detector was used to measure muons downstream of
ArgoNeuT. Though ArgoNeuT is primarily an R&D project, the data collected
provide a unique opportunity to measure neutrino cross sections in the 0.1-10
GeV energy range. Fully reconstructing the muon from these interactions is
imperative for these measurements. This paper focuses on the complete kinematic
reconstruction of neutrino-induced through-going muons tracks. Analysis of this
high statistics sample of minimum ionizing tracks demonstrates the reliability
of the geometric and calorimetric reconstruction in the ArgoNeuT detector
ArgoNeuT and the Neutrino-Argon Charged Current Quasi-Elastic Cross Section
ArgoNeuT, a Liquid Argon Time Projection Chamber in the NuMI beamline at
Fermilab, has recently collected thousands of neutrino and anti-neutrino events
between 0.1 and 10 GeV. The experiment will, among other things, measure the
cross section of the neutrino and anti-neutrino Charged Current Quasi-Elastic
interaction and analyze the vertex activity associated with such events. These
topics are discussed along with ArgoNeuT's automated reconstruction software,
currently capable of fully reconstructing the muon and finding the event vertex
in neutrino interactions.Comment: 6 pages, 4 figures, presented at the International Nuclear Physics
Conference, Vancouver, Canada, July 4-9, 2010, to be published in Journal of
Physics: Conference Series (JPCS
A phenomenological approach to the simulation of metabolism and proliferation dynamics of large tumour cell populations
A major goal of modern computational biology is to simulate the collective
behaviour of large cell populations starting from the intricate web of
molecular interactions occurring at the microscopic level. In this paper we
describe a simplified model of cell metabolism, growth and proliferation,
suitable for inclusion in a multicell simulator, now under development
(Chignola R and Milotti E 2004 Physica A 338 261-6). Nutrients regulate the
proliferation dynamics of tumor cells which adapt their behaviour to respond to
changes in the biochemical composition of the environment. This modeling of
nutrient metabolism and cell cycle at a mesoscopic scale level leads to a
continuous flow of information between the two disparate spatiotemporal scales
of molecular and cellular dynamics that can be simulated with modern computers
and tested experimentally.Comment: 58 pages, 7 figures, 3 tables, pdf onl
First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions
We report the first measurement of monoenergetic muon neutrino charged
current interactions. MiniBooNE has isolated 236 MeV muon neutrino events
originating from charged kaon decay at rest ()
at the NuMI beamline absorber. These signal -carbon events are
distinguished from primarily pion decay in flight and
backgrounds produced at the target station and decay pipe
using their arrival time and reconstructed muon energy. The significance of the
signal observation is at the 3.9 level. The muon kinetic energy,
neutrino-nucleus energy transfer (), and total cross
section for these events is extracted. This result is the first known-energy,
weak-interaction-only probe of the nucleus to yield a measurement of
using neutrinos, a quantity thus far only accessible through electron
scattering.Comment: 6 pages, 4 figure
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