23,883 research outputs found
Parsing as Reduction
We reduce phrase-representation parsing to dependency parsing. Our reduction
is grounded on a new intermediate representation, "head-ordered dependency
trees", shown to be isomorphic to constituent trees. By encoding order
information in the dependency labels, we show that any off-the-shelf, trainable
dependency parser can be used to produce constituents. When this parser is
non-projective, we can perform discontinuous parsing in a very natural manner.
Despite the simplicity of our approach, experiments show that the resulting
parsers are on par with strong baselines, such as the Berkeley parser for
English and the best single system in the SPMRL-2014 shared task. Results are
particularly striking for discontinuous parsing of German, where we surpass the
current state of the art by a wide margin
Global Existence of Weak Solutions to the Compressible Primitive Equations of Atmospheric Dynamics with Degenerate Viscosities
We show the existence of global weak solutions to the three-dimensional
compressible primitive equations of atmospheric dynamics with degenerate
viscosities. In analogy with the case of the compressible Navier-Stokes
equations, the weak solutions satisfy the basic energy inequality, the
Bresh-Desjardins entropy inequality and the Mellet-Vasseur estimate. These
estimates play an important role in establishing the compactness of the
vertical velocity of the approximating solutions, and therefore are essential
to recover the vertical velocity in the weak solutions
A dark energy multiverse
We present cosmic solutions corresponding to universes filled with dark and
phantom energy, all having a negative cosmological constant. All such solutions
contain infinite singularities, successively and equally distributed along
time, which can be either big bang/crunchs or big rips singularities.
Classicaly these solutions can be regarded as associated with multiverse
scenarios, being those corresponding to phantom energy that may describe the
current accelerating universe
Seidel elements and mirror transformations
The goal of this article is to give a precise relation between the mirror
symmetry transformation of Givental and the Seidel elements for a smooth
projective toric variety with nef. We show that the Seidel elements
entirely determine the mirror transformation and mirror coordinates.Comment: 36 pages. We corrected several issues as pointed out by the refere
A Cerberus‐Inspired Anti‐Infective Multicomponent Gatekeeper Hydrogel against Infections with the Emerging “Superbug” Yeast Candida auris
Report of the NAFO Commission Ad hoc Working Group to Reflect on the Rules Governing Bycatches, Discards and Selectivity (WG-BDS) in the NAFO Regulatory Area Meeting
1. Opening by the Chair, Temur Tairov (Russian Federation) 2. Appointment of Rapporteur
3. Adoption of Agenda 4. Discussion of the bycatch analysis performed by Scientific Council and the Secretariat
5. Action Plan in the Management and Minimization of Bycatch and Discards 6. Other Matters
a. STACTIC Intersessional Meeting, May 2017 b. WG-CR/CDAG Meeting, February and May 2017
c. NAFO Working Group on Improving Efficiency of NAFO Working Group Process 7. Recommendations to forward to the Commission
8. Adoption of Report 9. Adjournmen
Stabilized Schemes for the Hydrostatic Stokes Equations
Some new stable finite element (FE) schemes are presented for the hydrostatic Stokes
system or primitive equations of the ocean. It is known that the stability of the mixed formulation ap-
proximation for primitive equations requires the well-known Ladyzhenskaya–Babuˇska–Brezzi condi-
tion related to the Stokes problem and an extra inf-sup condition relating the pressure and the vertical
velocity.
The main goal of this paper is to avoid this extra condition by adding a residual stabilizing term to the
vertical momentum equation. Then, the stability for Stokes-stable FE combinations is extended to
the primitive equations and some error estimates are provided using Taylor–Hood P2 –P1 or miniele-
ment (P1 +bubble)–P1 FE approximations, showing the optimal convergence rate in the P2 –P1 case.
These results are also extended to the anisotropic (nonhydrostatic) problem. On the other hand,
by adding another residual term to the continuity equation, a better approximation of the vertical
derivative of pressure is obtained. In this case, stability and error estimates including this better
approximation are deduced, where optimal convergence rate is deduced in the (P 1 +bubble)–P1 case.
Finally, some numerical experiments are presented supporting previous results
Radiatively induced leptogenesis in a minimal seesaw model
We study the possibility that the baryon asymmetry of the universe is
generated in a minimal seesaw scenario where two right-handed Majorana
neutrinos with degenerate masses are added to the standard model particle
content. In the usual framework of thermal leptogenesis, a nonzero
asymmetry can be obtained through the mass splitting induced by the running of
the heavy Majorana neutrino masses from their degeneracy scale down to the
seesaw scale. Although, in the light of the present neutrino oscillation data,
the produced baryon asymmetry turns out to be smaller than the experimental
value, the present mechanism could be viable in simple extensions of the
standard model.Comment: 6 pages, 2 figures, uses RevTeX4, calculations improved, comments
adde
Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale
We present a study of the HII regions in the galaxy NGC 6754 from a two
pointing mosaic comprising 197,637 individual spectra, using Integral Field
Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science
Verification program. The data cover the entire galaxy out to ~2 effective
radii (re ), sampling its morphological structures with unprecedented spatial
resolution for a wide-field IFU. A complete census of the H ii regions limited
by the atmospheric seeing conditions was derived, comprising 396 individual
ionized sources. This is one of the largest and most complete catalogue of H ii
regions with spectroscopic information in a single galaxy. We use this
catalogue to derive the radial abundance gradient in this SBb galaxy, finding a
negative gradient with a slope consistent with the characteristic value for
disk galaxies recently reported. The large number of H ii regions allow us to
estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong
constraints on the proposed mechanisms for metal mixing in disk galaxies, like
radial movements associated with bars and spiral arms, when comparing with
simulations. We found evidence for an azimuthal variation of the oxygen
abundance, that may be related with the radial migration. These results
illustrate the unique capabilities of MUSE for the study of the enrichment
mechanisms in Local Universe galaxies.Comment: 13 pages, 7 Figurs, accepted for publishing in A&
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