1,405 research outputs found
Generating Abstractive Summaries from Meeting Transcripts
Summaries of meetings are very important as they convey the essential content
of discussions in a concise form. Generally, it is time consuming to read and
understand the whole documents. Therefore, summaries play an important role as
the readers are interested in only the important context of discussions. In
this work, we address the task of meeting document summarization. Automatic
summarization systems on meeting conversations developed so far have been
primarily extractive, resulting in unacceptable summaries that are hard to
read. The extracted utterances contain disfluencies that affect the quality of
the extractive summaries. To make summaries much more readable, we propose an
approach to generating abstractive summaries by fusing important content from
several utterances. We first separate meeting transcripts into various topic
segments, and then identify the important utterances in each segment using a
supervised learning approach. The important utterances are then combined
together to generate a one-sentence summary. In the text generation step, the
dependency parses of the utterances in each segment are combined together to
create a directed graph. The most informative and well-formed sub-graph
obtained by integer linear programming (ILP) is selected to generate a
one-sentence summary for each topic segment. The ILP formulation reduces
disfluencies by leveraging grammatical relations that are more prominent in
non-conversational style of text, and therefore generates summaries that is
comparable to human-written abstractive summaries. Experimental results show
that our method can generate more informative summaries than the baselines. In
addition, readability assessments by human judges as well as log-likelihood
estimates obtained from the dependency parser show that our generated summaries
are significantly readable and well-formed.Comment: 10 pages, Proceedings of the 2015 ACM Symposium on Document
Engineering, DocEng' 201
Biosurfactant production and surface translocation are regulated by PlcR in Bacillus cereus ATCC 14579 under low nutrient conditions
Bacillus cereus ATCC 14579 can respond to nutrient changes by adopting different forms of surface translocation. The B. cereus ATCC 14579 DeltaplcR mutant, but not the wild type, formed dendritic (branched) patterns on EPS [a low-nutrient medium that contains 7.0 g K(2)HPO(4), 3.0 g KH(2)PO(4), 0.1 g MgSO(4).7H(2)O, 0.1 g (NH(4))(2)SO(4), 0.01 g CaCl(2), 0.001 g FeSO(4), 0.1 g NaCl, 1.0 g glucose, and 125 mg yeast extract per liter] containing 0.7% agar. The dendritic patterns formed by sliding translocation of nonflagellated cells are enhanced under low-nutrient conditions and require sufficient production of a biosurfactant, which appears to be repressed by PlcR. The wild-type and complemented strains failed to slide on the surface of EPS agar because of the production of low levels of biosurfactant. Precoating EPS agar surfaces with surfactin (a biosurfactant produced by Bacillus subtilis) or biosurfactant purified from the DeltaplcR mutant rescued the ability of the wild-type and complemented strains to slide. When grown on a nutrient-rich medium like Luria-Bertani agar, both the wild-type and DeltaplcR mutant strains produced flagella. The wild type was hyperflagellated and elongated and exhibited swarming behavior, while the DeltaplcR mutant was multiflagellated and the cells often formed long chains but did not swarm. Thin-layer chromatography and mass spectrometry analyses suggested that the biosurfactant purified from the DeltaplcR mutant was a lipopeptide and had a mass of 1,278.1722 (m/z). This biosurfactant has hemolytic activity and inhibited the growth of several gram-positive bacteria
A new approach to axial coupling constants in the QCD sum rule
We derive new QCD sum rules for the axial coupling constants by considering
two-point correlation functions of the axial-vector currents in a one nucleon
state. The QCD sum rules tell us that the axial coupling constants are
expressed by nucleon matrix elements of quark and gluon operators which are
related to the sigma terms and the moments of parton distribution functions.
The results for the iso-vector axial coupling constants and the 8th component
of the SU(3) octet are in good agreement with experiment.Comment: 10 pages, 1 figure include
Flavor and Spin Contents of the Nucleon in the Quark Model with Chiral Symmetry
A simple calculation in the framework of the chiral quark theory of Manohar
and Georgi yields results that can account for many of the ''failures'' of the
naive quark model: significant strange quark content in the nucleon as
indicated by the value of the -
asymmetry in the nucleon as measured by the deviation from Gottfried sum rule
and by the Drell-Yan process, as well as the various quark contributions to the
nucleon spin as measured by the deep inelastic polarized lepton-nucleon
scatterings.Comment: figure has been separated from tex file. No other changes. Preprint
CMU-HEP94-3
Inactivation of the Osteopontin Gene Enhances Vascular Calcification of Matrix Gla Protein–deficient Mice: Evidence for Osteopontin as an Inducible Inhibitor of Vascular Calcification In Vivo
Osteopontin (OPN) is abundantly expressed in human calcified arteries. To examine the role of OPN in vascular calcification, OPN mutant mice were crossed with matrix Gla protein (MGP) mutant mice. Mice deficient in MGP alone (MGP−/− OPN+/+) showed calcification of their arteries as early as 2 weeks (wk) after birth (0.33 ± 0.01 mmol/g dry weight), and the expression of OPN in the calcified arteries was greatly up-regulated compared with MGP wild-types. OPN accumulated adjacent to the mineral and colocalized to surrounding cells in the calcified media. Cells synthesizing OPN lacked smooth muscle (SM) lineage markers, SM α-actin and SM22α. However, most of them were not macrophages. Importantly, mice deficient in both MGP and OPN had twice as much arterial calcification as MGP−/− OPN+/+ at 2 wk, and over 3 times as much at 4 wk, suggesting an inhibitory effect of OPN in vascular calcification. Moreover, these mice died significantly earlier (4.4 ± 0.2 wk) than MGP−/− OPN+/+ counterparts (6.6 ± 1.0 wk). The cause of death in these animals was found to be vascular rupture followed by hemorrhage, most likely due to enhanced calcification. These studies are the first to demonstrate a role for OPN as an inducible inhibitor of ectopic calcification in vivo
Excitonic effects in the optical properties of SiC sheet and nanotubes
The quasiparticle band structure and optical properties of single-walled
zigzag and armchair SiC nanotubes (SiC-NTs) as well as single SiC sheet are
investigated by ab initio many-body calculations using the GW and the GW plus
Bethe-Salpeter equation (GW+BSE) approaches, respectively. Significant GW
quasiparticle corrections of more than 1.0 eV to the Kohn-Sham band gaps from
the local density approximation (LDA) calculations are found. The GW
self-energy corrections transform the SiC sheet from a indirect LDA band gap to
a direct band gap material. Furthermore, the quasiparticle band gaps of SiC-NTs
with different chiralities behave very differently as a function of tube
diameter, and this can be attributed to the difference in the curvature-induced
orbital rehybridization between the different chiral nanotubes. The calculated
optical absorption spectra are dominated by discrete exciton peaks due to
exciton states with large binding energy up to 2.0 eV in the SiC sheet and
SiC-NTs. The formation of strongly bound excitons is attributed to the enhanced
electron-hole interaction in these low dimensional systems. Remarkably, the
excited electron amplitude of the exciton wavefunction is found to peak on the
Si atoms near the hole position (which is on the C site) in the zigzag SiC-NTs,
indicating a charge transfer from an anion (hole) to its neighboring cations by
photoexcitation. In contrast, this pronounced peak structure disappear in the
exciton wavefunction in the armchair SiC-NTs. Furthermore, in the armchair
SiC-NTs, the bound exciton wavefunctions are more localized and also strongly
cylindrically asymmetric
Normal-state magnetic susceptibility in a bilayer cuprate
The magnetic susceptibility of high-T_c superconductors is investigated in
the normal state using a coupled bilayer model. While this model describes in a
natural way the normal-state pseudogaps seen in c-axis optical conductivity on
underdoped samples, it predicts a weakly increasing susceptibility with
decreasing temperature and cannot explain the magnetic pseudogaps exhibited in
NMR measurements. Our result, together with some experimental evidence suggest
that the mechanism governing the c-axis optical pseudogap is different from
that for the plane magnetic pseudogap.Comment: 5 pages, 2 figure
Nucleon Decay Matrix Elements from Lattice QCD
We present a model-independent calculation of hadron matrix elements for all
dimension-six operators associated with baryon number violating processes using
lattice QCD. The calculation is performed with the Wilson quark action in the
quenched approximation at on a
lattice. Our results cover all the matrix elements required to estimate the
partial lifetimes of (proton,neutron)() +() decay modes. We point out the necessity of disentangling two
form factors that contribute to the matrix element; previous calculations did
not make the separation, which led to an underestimate of the physical matrix
elements. With a correct separation, we find that the matrix elements have
values 3-5 times larger than the smallest estimates employed in
phenomenological analyses of the nucleon decays, which could give strong
constraints on several GUT models. We also find that the values of the matrix
elements are comparable with the tree-level predictions of chiral lagrangian.Comment: 53 pages, 18 eps figure
Does One Need the Anomaly to Describe the Polarized Structure Functions?
The SLAC data on the p, d and n polarized structure functions are fairly well
reproduced with and without the contribution of the anomaly. The results are
compared with a previous study based mainly on SMC data. The implications on
the solution of the spin-crisis are discussed.Comment: 10 pages LaTeX + 5 uuencoded figure
The pseudogap in high-temperature superconductors: an experimental survey
We present an experimental review of the nature of the pseudogap in the
cuprate superconductors. Evidence from various experimental techniques points
to a common phenomenology. The pseudogap is seen in all high temperature
superconductors and there is general agreement on the temperature and doping
range where it exists. It is also becoming clear that the superconducting gap
emerges from the normal state pseudogap. The d-wave nature of the order
parameter holds for both the superconducting gap and the pseudogap. Although an
extensive body of evidence is reviewed, a consensus on the origin of the
pseudogap is as lacking as it is for the mechanism underlying high temperature
superconductivity.Comment: review article, 54 pages, 50 figure
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