60,267 research outputs found
A sharp vanishing theorem for line bundles on K3 or Enriques surfaces
Let be a line bundle on a K3 or Enriques surface. We give a vanishing
theorem for that, unlike most vanishing theorems, gives necessary and
sufficient geometrical conditions for the vanishing. This result is essential
in our study of Brill-Noether theory of curves on Enriques surfaces (reference
[KL1]) and of Enriques-Fano threefolds (reference [KLM]).Comment: 4 pages, latex. Minor corrections. To appear on Proc. Amer. Math. So
Quasinormal modes of Charged Regular Black Hole
The quasinormal modes (QNMs) of a regular black hole with charge are
calculated in the eikonal approximation. In the eikonal limit the QNMs of black
hole are determined by the parameters of the unstable circular null geodesics.
The behaviors of QNMs are compared with QNMs of Reisner-Nordstr\"{o}m black
hole, it is done by fixing some of the parameters that characterize the black
holes and varying another. We observed that the parameter that is related one
effective cosmological constant at small distances , determines the behaviors
of the QNMs of regular black hole with charge.Comment: arXiv admin note: text overlap with arXiv:1607.0247
Architecture independent environment for developing engineering software on MIMD computers
Engineers are constantly faced with solving problems of increasing complexity and detail. Multiple Instruction stream Multiple Data stream (MIMD) computers have been developed to overcome the performance limitations of serial computers. The hardware architectures of MIMD computers vary considerably and are much more sophisticated than serial computers. Developing large scale software for a variety of MIMD computers is difficult and expensive. There is a need to provide tools that facilitate programming these machines. First, the issues that must be considered to develop those tools are examined. The two main areas of concern were architecture independence and data management. Architecture independent software facilitates software portability and improves the longevity and utility of the software product. It provides some form of insurance for the investment of time and effort that goes into developing the software. The management of data is a crucial aspect of solving large engineering problems. It must be considered in light of the new hardware organizations that are available. Second, the functional design and implementation of a software environment that facilitates developing architecture independent software for large engineering applications are described. The topics of discussion include: a description of the model that supports the development of architecture independent software; identifying and exploiting concurrency within the application program; data coherence; engineering data base and memory management
New Precision Electroweak Tests of SU(5) x U(1) Supergravity
We explore the one-loop electroweak radiative corrections in supergravity via explicit calculation of vacuum-polarization and
vertex-correction contributions to the and
parameters. Experimentally, these parameters are obtained from a global fit to
the set of observables , and . We
include -dependent effects, which induce a large systematic negative shift
on for light chargino masses (m_{\chi^\pm_1}\lsim70\GeV). The
(non-oblique) supersymmetric vertex corrections to \Zbb, which define the
parameter, show a significant positive shift for light chargino
masses, which for can be nearly compensated by a negative
shift from the charged Higgs contribution. We conclude that at the 90\%CL, for
m_t\lsim160\GeV the present experimental values of and
do not constrain in any way supergravity in
both no-scale and dilaton scenarios. On the other hand, for m_t\gsim160\GeV
the constraints on the parameter space become increasingly stricter. We
demonstrate this trend with a study of the m_t=170\GeV case, where only a
small region of parameter space, with \tan\beta\gsim4, remains allowed and
corresponds to light chargino masses (m_{\chi^\pm_1}\lsim70\GeV). Thus
supergravity combined with high-precision LEP data would
suggest the presence of light charginos if the top quark is not detected at the
Tevatron.Comment: LaTeX, 11 Pages+4 Figures(not included), the figures available upon
request as an uuencoded file(0.4MB) or 4 PS files from [email protected],
CERN-TH.7078/93, CTP-TAMU-68/93, ACT-24/9
Limnology in Argentina: An historical account
This short review includes major books, articles and episodes concerned with studies on inland waters that have affected the development of limnology in Argentina. It is divided into three periods; (1) an early period of protolimnologists; (2) a period previous to the present times, subdivided into a first stage from 1900 to 1938 and a second stage from 1938 to 1962; and (3) a period of integrated research
Subvarieties of generic hypersurfaces in any variety
Let W be a projective variety of dimension n+1, L a free line bundle on W, X
in a hypersurface of degree d which is generic among those given by
sums of monomials from , and let be a generically finite map
from a smooth m-fold Y. We suppose that f is r-filling, i.e. upon deforming X
in , f deforms in a family such that the corresponding deformations
of dominate . Under these hypotheses we give a lower bound for the
dimension of a certain linear system on the Cartesian product having
certain vanishing order on a diagonal locus as well as on a double point locus.
This yields as one application a lower bound on the dimension of the linear
system |K_{Y} - (d - n + m)f^*L - f^*K_{W}| which generalizes results of Ein
and Xu (and in weaker form, Voisin). As another perhaps more surprising
application, we conclude a lower bound on the number of quadrics containing
certain projective images of Y.Comment: We made some improvements in the introduction and definitions. In an
effort to clarify the arguments we separated the 1-filling case from the
r-filling case and we gave a more detailed proof of the key lemma. The
article will appear in the Math. Proc. Cambridge Philos. So
Characterizing the radial oxygen abundance distribution in disk galaxies
We examine the possible dependence of the radial oxygen abundance
distribution on non-axisymmetrical structures (bar/spirals) and other
macroscopic parameters such as the mass, the optical radius R25, the color g-r,
and the surface brightness of the galaxy. A sample of disk galaxies from the
CALIFA DR3 is considered. We adopted the Fourier amplitude A2 of the surface
brightness as a quantitative characteristic of the strength of non-axisymmetric
structures in a galactic disk, in addition to the commonly used morphologic
division for A, AB, and B types based on the Hubble classification. To
distinguish changes in local oxygen abundance caused by the non-axisymmetrical
structures, the multiparametric mass--metallicity relation was constructed as a
function of parameters such as the bar/spiral pattern strength, the disk size,
color index g-r in the SDSS bands, and central surface brightness of the disk.
The gas-phase oxygen abundance gradient is determined by using the R
calibration. We find that there is no significant impact of the
non-axisymmetric structures such as a bar and/or spiral patterns on the local
oxygen abundance and radial oxygen abundance gradient of disk galaxies.
Galaxies with higher mass, however, exhibit flatter oxygen abundance gradients
in units of dex/kpc, but this effect is significantly less prominent for the
oxygen abundance gradients in units of dex/R25 and almost disappears when the
inner parts are avoided. We show that the oxygen abundance in the central part
of the galaxy depends neither on the optical radius R25 nor on the color g-r or
the surface brightness of the galaxy. Instead, outside the central part of the
galaxy, the oxygen abundance increases with g-r value and central surface
brightness of the disk.Comment: 11 pages, 6 figures; accepted for publication in A&
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