6,023 research outputs found
Mean field study of structural changes in Pt isotopes with the Gogny interaction
The evolution of the nuclear shapes along the triaxial landscape is studied
in the Pt isotopic chain using the selfconsistent Hartree-Fock-Bogoliubov
approximation based on the Gogny interaction. In addition to the
parametrization D1S, the new incarnations D1N and D1M of this force are also
included in our analysis to asses to which extent the predictions are
independent of details of the effective interaction. The considered range of
neutron numbers 88<N<26 includes prolate, triaxial, oblate and spherical ground
state shapes and serves for a detailed comparison of the predictions obtained
with the new sets D1N and D1M against the ones provided by the standard
parametrization Gogny-D1S in a region of the nuclear landscape for which
experimental and theoretical fingerprints of shape transitions have been found.
Structural evolution along the Pt chain is discussed in terms of the
deformation dependence of single particle energies.Comment: 18 pages, 10 figures. Accepted for publication in Phys. Rev.
The redshift and broad band spectral energy distribution of NRAO 150
Context. NRAO 150 is one of the brightest radio and mm AGN sources on the
northern sky. It has been revealed as an interesting source where to study
extreme relativistic jet phenomena. However, its cosmological distance has not
been reported so far, because of its optical faintness produced by strong
Galactic extinction.
Aims. Aiming at measuring the redshift of NRAO 150, and hence to start making
possible quantitative studies from the source.
Methods. We have conducted spectroscopic and photometric observations of the
source in the near-IR, as well as in the optical.
Results. All such observations have been successful in detecting the source.
The near-IR spectroscopic observations reveal strong H and H
emission lines from which the cosmological redshift of NRAO 150
() has been determined for the first time. We classify the
source as a flat-spectrum radio-loud quasar, for which we estimate a large
super-massive black-hole mass . After
extinction correction, the new near-IR and optical data have revealed a
high-luminosity continuum-emission excess in the optical (peaking at
\,\AA, rest frame) that we attribute to thermal emission from the
accretion disk for which we estimate a high accretion rate, \,% of the
Eddington limit.
Conclusions. Comparison of these source properties, and its broad-band
spectral-energy distribution, with those of Fermi blazars allow us to predict
that NRAO 150 is among the most powerful blazars, and hence a high luminosity
-although not detected yet- -ray emitter.Comment: 8 pages, 4 figure
Real time phase-slopes calculations by correlations using FPGAs
J. Trujillo Sevilla ; M. R. Valido ; L. F. Rodríguez Ramos ; E. Boemo ; F. Rosa ; J. M. Rodríguez Ramos, “Real time phase-slopes calculations by correlations using FPGAs,” Proc. SPIE 7015, Adaptive Optics Systems, 70153B (July 11, 2008), Norbert Hubin; Claire E. Max; Peter L. Wizinowich
, 7015 (Issue) 70153B, (2008). Copyright © 2008 SPIE Society of Photo‑Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.ELT laser guide star wavefront sensors are planned to handle an expected amount of data to be overwhelmingly large
(1600x1600 pixels at 700 fps). According to the calculations involved, the solutions must consider to run on specialized
hardware as Graphical Processing Units (GPUs) or Field Programmable Gate Arrays (FPGAs), among others.
In the case of a Shack-Hartmann wavefront sensor is finally selected, the wavefront slopes can be computed using
centroid or correlation algorithms. Most of the developments are designed using centroid algorithms, but precision ought
to be taken in account too, and then correlation algorithms are really competitive.
This paper presents an FPGA-based wavefront slope implementation, capable of handling the sensor output stream in a
massively parallel approach, using a correlation algorithm previously tested and compared to the centroid algorithm.
Time processing results are shown, and they demonstrate the ability of the FPGA integer arithmetic in the resolution of
AO problems.
The selected architecture is based in today’s commercially available FPGAs which have a very limited amount of
internal memory. This limits the dimensions used in our implementation, but this also means that there is a lot of margin
to move real-time algorithms from the conventionalThis work has been partially supported by “Programa Nacional de Diseño y Producción Industrial" (Project DPI 2006-
07906) of the “Ministerio de Educación y Ciencia" of the Spanish Government, and by “European Regional
Development Fund" (ERDF)
Quadrupole-octupole coupling and the onset of octupole deformation in actinides
The evolution of quadrupole and octupole collectivity and their coupling is
investigated in a series of even-even isotopes of the actinide Ra, Th, U, Pu,
Cm, and Cf with neutron number in the interval .
The Hartree-Fock-Bogoliubov approximation, based on the parametrization D1M of
the Gogny energy density functional, is employed to generate potential energy
surfaces depending upon the axially-symmetric quadrupole and octupole shape
degrees of freedom. The mean-field energy surface is then mapped onto the
expectation value of the interacting-boson-model Hamiltonian in the boson
condensate state as to determine the strength parameters of the boson
Hamiltonian. Spectroscopic properties related to the octupole degree of freedom
are produced by diagonalizing the mapped Hamiltonian. Calculated low-energy
negative-parity spectra, reduced transition
rates, and effective octupole deformation suggest that the transition from
nearly spherical to stable octupole-deformed, and to octupole vibrational
states occurs systematically in the actinide region.Comment: 12 pages, 12 figure
Herbage Mass and \u3cem\u3ein Situ\u3c/em\u3e Dry Matter Ruminal Degradation Kinetics of \u3cem\u3eBrachiaria\u3c/em\u3e spp
In Puerto Rico, Brachiaria decumbens cv. Basilisk has been promoted as a potential forage for acid soils and humid areas, but with limited success. Recently, B. brizantha cv. Marandú and a hybrid (B. brizantha x B. Ruziziensis) cv. Mulato were introduced for evaluation on acid soils and as a potential replacement for cv. Basilisk, but little information is available on yield performance under grazing or nutritive value. The objective of this study was to assess herbage mass and nutritive value of grazed pastures consisting of Basilisk, Marandú, and Mulato and determine the rate of in situ dry matter degradation
Octupole correlations in light actinides from the interacting boson model based on the Gogny energy density functional
The quadrupole-octupole coupling and the related spectroscopic properties
have been studied for the even-even light actinides Ra and
Th. The Hartree-Fock-Bogoliubov approximation, based on the
Gogny-D1M energy density functional, has been employed as a microscopic input,
i.e., to obtain (axially symmetric) mean-field potential energy surfaces as
functions of the quadrupole and octupole deformation parameters. The mean-field
potential energy surfaces have been mapped onto the corresponding bosonic
potential energy surfaces using the expectation value of the Interacting
Boson Model (IBM) Hamiltonian in the boson condensate state. The strength
parameters of the -IBM Hamiltonian have been determined via this mapping
procedure. The diagonalization of the mapped IBM Hamiltonian provides energies
for positive- and negative-parity states as well as wave functions which are
employed to obtain transitional strengths. The results of the calculations
compare well with available data from Coulomb excitation experiments and point
towards a pronounced octupole collectivity around Ra and Th.Comment: 15 pages, 10 figures, 1 tabl
Sobre arqueologías de liberación en una “colonia postcolonial” (Puerto Rico).
This paper analyzes some historical and recent issues of the archaeological practices that are taking place in Puerto Rico and other eccentric contexts in order to expose the multiple vectors of colonialism that are embedded today in the structure and praxis of the discipline. Some of the recent manifestations of postcolonial thought (and its respective critiques) are used to contextualize the atypical socio-political situation of Puerto Rico, which has been recently characterized as a “postcolonial colony.” We suggest that the socio political context in which the archaeology of Puerto Rico was created and developed influenced enormously the structure of the discipline in the island, which has led to a colonized production of knowledge, narratives, and representations of our ancient history. We propose, as an alternative against the naturalization of colonialism in the practice of archaeology in the island and other eccentric territories, the articulation of a new moral and ethical order within the discipline that we have named “archaeologies of liberation”.Este artículo analiza algunos elementos históricos y recientes de la práctica arqueológica mundial y de Puerto Rico, con la finalidad de exponer los múltiples vectores de colonialismo existentes en la praxis y narrativa de la disciplina, tanto a nivel local como global. El eje central del presente análisis se fundamenta en algunas de las recientes manifestaciones del pensamiento postcolonial mundial (y las críticas hechas a éste) para situar a Puerto Rico en el atípico escenario sociopolítico en el que se encuentra. Se plantea que el contexto sociopolítico en el cual se creó y desarrolló la arqueología de Puerto Rico influyó enormemente en la estructura de esta disciplina, provocando que la producción de conocimientos sobre nuestra historia antigua haya estado (y siga estando) condicionada a prácticas, narrativas y representaciones culturales de carácter colonial. Proponemos, como alternativa en contra de la naturalización del colonialismo en la arqueología de la Isla y de otros territorios excéntricos, el surgimiento y desarrollo de un nuevo orden moral y ético al interior de la disciplina, el cual hemos denominado “arqueologías de liberación”
Maxwell homogenization scheme for piezoelectric composites with arbitrarily-oriented spheroidal inhomogeneities
International audienc
High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263
We report high spatial resolution i' band imaging of the multiple T Tauri
system LkH 262/LkH 263 obtained during the first commissioning
period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel
Telescope, using its Lucky Imaging mode. AOLI images have provided photometry
for each of the two components LkH 263 A and B (0.41 arcsec separation)
and marginal evidence for an unresolved binary or a disc in LkH 262.
The AOLI data combined with previously available and newly obtained optical and
infrared imaging show that the three components of LkH 263 are
co-moving, that there is orbital motion in the AB pair, and, remarkably, that
LkH 262-263 is a common proper motion system with less than 1 mas/yr
relative motion. We argue that this is a likely five-component gravitationally
bounded system. According to BT-settl models the mass of each of the five
components is close to 0.4 M and the age is in the range 1-2 Myr. The
presence of discs in some of the components offers an interesting opportunity
to investigate the formation and evolution of discs in the early stages of
multiple very low-mass systems. In particular, we provide tentative evidence
that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May
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