22,608 research outputs found
Una mirada a un grupo de nombres de lugar de reciente creación en un municipio español: algunas semejanzas y diferencias con los topónimos antiguos
The present work is focused on toponyms of recent creation. These new place
names have generally received less attention among scholars than those with a long
history, which have often generated passionate debates and academic papers about
their origins. The group analyzed here was discarded from the index list resulting
from a toponymy survey made in the village of Gata (Cáceres) in 2014. They are less
than one hundred years old, and do not appear to be registered as toponyms in any
known written source. However, their analysis reveals that the necessity for a social
community to give names to the places it inhabits, and the process for the creation
of new toponyms has essentially not changed for centuries.El presente trabajo se centra en los topónimos de reciente creación. Este grupo ha
recibido generalmente menos atención por parte de los investigadores que aquellos
otros que cuentan con una historia más larga, los cuales han sido con frecuencia
objeto de apasionados debates acerca de su origen y generado numerosos trabajos
académicos. La nómina de los aquí analizados está formada por el grupo de los no
tomados en consideración para formar porte del corpus topónimo de Gata (Cáceres)
efectuado en 2014 por tener menos de un siglo de antigüedad y no aparecer en
ninguna de las fuentes escritas consultadas. Sim embargo, su análisis revela que para
una comunidad rural la necesidad de darle un nombre a los lugares de su entorno y
el proceso de creación de nuevos topónimos no ha variado sustancialmente desde
la antigüedad
A Next-to-Minimal Supersymmetric Model of Hybrid Inflation
We propose a model of inflation based on a simple variant of the NMSSM,
called NMSSM, where the additional singlet plays the role of the
inflaton in hybrid (or inverted hybrid) type models. As in the original NMSSM,
the NMSSM solves the problem of the MSSM via the VEV of a gauge
singlet , but unlike the NMSSM does not suffer from domain wall problems
since the offending symmetry is replaced by an approximate Peccei-Quinn
symmetry which also solves the strong CP problem, and leads to an invisible
axion with interesting cosmological consequences. The PQ symmetry may arise
from a superstring model with an exact discrete symmetry after
compactification. The model predicts a spectral index to one part in
.Comment: 17 pages, Latex; note added, accepted for Phys. Lett.
Palomar/Las Campanas Imaging Atlas of Blue Compact Dwarf Galaxies: II. Surface Photometry and the Properties of the Underlying Stellar Population
We present the results from an analysis of surface photometry of B, R, and
Halpha images of a total of 114 nearby galaxies drawn from the Palomar/Las
Campanas Imaging Atlas of Blue Compact Dwarf galaxies. Surface brightness and
color profiles for the complete sample have been obtained. We determine the
exponential and Sersic profiles that best fit the surface brightness
distribution of the underlying stellar population detected in these galaxies.
We also compute the (B-R) color and total absolute magnitude of the underlying
stellar population and compared them to the integrated properties of the
galaxies in the sample. Our analysis shows that the (B-R) color of the
underlying population is systematically redder than the integrated color,
except in those galaxies where the integrated colors are strongly contaminated
by line and nebular-continuum emission. We also find that galaxies with
relatively red underlying stellar populations (typically (B-R)>~1mag) show
structural properties compatible with those of dwarf elliptical galaxies (i.e.
a smooth light distribution, fainter extrapolated central surface brightness
and larger scale lengths than BCD galaxies with blue underlying stellar
populations). At least ~15% of the galaxies in the sample are compatible with
being dwarf elliptical (dE) galaxies experiencing a burst of star formation.
For the remaining BCD galaxies in the sample we do not find any correlation
between the recent star formation activity and their structural differences
with respect to other types of dwarf galaxies.Comment: 35 pages, 6 figures, accepted for publication in ApJS. Postscript
files of panels f1a-f1o of figure 1 are available online at
http://www.ociw.edu/~agpaz/astro-ph/apjs2004
The braking indices in pulsar emission models
Using the method proposed in a previous paper, we calculate pulsar braking
indices in the models with torque contributions from both inner and outer
accelerating regions, assuming that the interaction between them is negligible.
We suggest that it is likely that the inverse Compton scattering induced polar
vacuum gap and the outer gap coexist in the pulsar magnetosphere. We include
the new near threshold vacuum gap models with curvature-radiation and inverse
Compton scattering induced cascades, respectively; and find that these models
can well reproduce the measured values of the braking indices.Comment: A&Ap accepted, or at
http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.ht
Exhumation of the Sierra de Cameros (Iberian Range, Spain): constraints from low-temperature thermochronology
We present new fission-track and (U–Th)/He data from apatite and zircon in order to
reconstruct the exhumation of the Sierra de Cameros, in the northwestern part of Iberian Range,
Spain. Zircon fission-track ages from samples from the depocentre of the basin were reset
during the metamorphic peak at approximately 100 Ma. Detrital apatites from the uppermost sediments
retain fission-track age information that is older than the sediment deposition age, indicating
that these rocks have not exceeded 110 8C. Apatites from deeper in the stratigraphic sequence of
the central part of the basin have fission-track ages of around 40 Ma, significantly younger than
the stratigraphic age, recording the time of cooling after peak metamorphic conditions. Apatite
(U–Th)/He ages in samples from these sediments are 31–40 Ma and record the last period of
cooling during Alpine compression. The modelled thermal history derived from the uppermost
sediments indicates that the thermal pulse associated with peak metamorphism was rapid, and
that the region has cooled continuously to the present. The estimated palaeogeothermal gradient
is around 86 8C km21 and supports a tectonic model with a thick sedimentary fill (c. 8 km) and
explains the origin of the low-grade metamorphism observed in the oldest sediments
Fissidentetum taxifolii Waldheim 1944 Rhizomnietosum Punctati subas. Nova en el piso supramediterráneo de Sierra Nevada (Granada, España)
La asociación Fissidentetu^ taxifolii Waldheim 1944 rhizonnietosu^ punctati subas. nova, ha sido observada en taludes hómedos del piso supramediterráneo de Sierra Nevada. Aparece ligada al bioclima de formaciones boscosas de Quercus pyrenaica Willd., mostrando una posición finícola y relictica en el sur de Europa.L'association Fissidentetu^ taxifolii Waldheim 1944 rhizoanietosu^ punctati subas. nova, est observée a Sierra Nevada dans les talus humides de l'étage supraméditerranéen; elle est liée au bioclimat des formations forestiers du Quercus pyrenaica Willd., montrant une position finicole et rélictique
A Bosonic Analog of a Topological Dirac Semi-Metal: Effective Theory, Neighboring Phases, and Wire Construction
We construct a bosonic analog of a two-dimensional topological Dirac
Semi-Metal (DSM). The low-energy description of the most basic 2D DSM model
consists of two Dirac cones at positions in momentum space.
The local stability of the Dirac cones is guaranteed by a composite symmetry
, where is time-reversal and is
inversion. This model also exhibits interesting time-reversal and inversion
symmetry breaking electromagnetic responses. In this work we construct a
bosonic version by replacing each Dirac cone with a copy of the
Nonlinear Sigma Model (NLSM) with topological theta term and theta angle
. One copy of this NLSM also describes the gapless surface
termination of the 3D Bosonic Topological Insulator (BTI). We compute the
time-reversal and inversion symmetry breaking electromagnetic responses for our
model and show that they are twice the value one gets in the DSM case matching
what one might expect from, for example, a bosonic Chern insulator. We also
investigate the stability of the BSM model and find that the composite
symmetry again plays an important role. Along the way we
clarify many aspects of the surface theory of the BTI including the
electromagnetic response, the charges and statistics of vortex excitations, and
the stability to symmetry-allowed perturbations. We briefly comment on the
relation between the various descriptions of the NLSM with
used in this paper (a dual vortex description and a description in terms of
four massless fermions) and the recently proposed dual description of the BTI
surface in terms of dimensional Quantum Electrodynamics with two flavors
of fermion ( QED). In a set of four Appendixes we review some of the
tools used in the paper, and also derive some of the more technical results.Comment: 33 pages, 4 appendixes, v2: small corrections and added references,
v3: new section added (Sec. VI) and additional references. To appear in PR
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