16,773 research outputs found
Lovelock gravities from Born-Infeld gravity theory
We present a Born-Infeld gravity theory based on generalizations of Maxwell
symmetries denoted as . We analyze different configuration
limits allowing to recover diverse Lovelock gravity actions in six dimensions.
Further, the generalization to higher even dimensions is also considered.Comment: v3, 15 pages, two references added, published versio
Tailored particle current in an optical lattice by a weak time-symmetric harmonic potential
Quantum ratchets exhibit asymptotic currents when driven by a time-periodic
potential of zero mean if the proper spatio-temporal symmetries are broken.
There has been recent debate on whether directed currents may arise for
potentials which do not break these symmetries. We show here that, in the
presence of degeneracies in the quasienergy spectrum, long-lasting directed
currents can be induced, even if the time reversal symmetry is not broken. Our
model can be realized with ultracold atoms in optical lattices in the
tight-binding regime, and we show that the time scale of the average current
can be controlled by extremely weak fields.Comment: 4 pages, 4 figure
Functional centrality in graphs
In this paper we introduce the functional centrality as a generalization of
the subgraph centrality. We propose a general method for characterizing nodes
in the graph according to the number of closed walks starting and ending at the
node. Closed walks are appropriately weighted according to the topological
features that we need to measure
Mercury and selenium binding biomolecules in terrestrial mammals (Cervus elaphus and Sus scrofa) from a mercury exposed area
Acknowledgements The authors are grateful to Junta de Comunidades de Castilla-La Mancha (PCC-05-004-2, PAI06-0094, PCI-08-0096, PEII09-0032-5329) and the Ministerio de Economía y Competitividad (CTQ2013-48411-P) for financial support. M.J. Patiño Ropero acknowledges the Junta de Comunidades de Castilla-La Mancha for her PhD. fellowship.Peer reviewedPostprin
Two photon decay of neutral scalars below 1.5 GeV in a chiral model for bar{q}q and bar{q}bar{q}qq states
We study the two photon decay of neutral scalars below 1.5 GeV in the context
of a recently proposed chiral model for bar{q}q and bar{q}bar{q}qq states. We
find good agreement with experimental results for the a_{0}(980)->gamma gamma.
Our calculations for f_{0}(980)->gamma gamma shows that further work is
necessary in order to understand the structure of this meson. The model
predicts Gamma(a_{0}(1450)->gamma gamma)=0.16+/-0.10KeV, Gamma(sigma->gamma
gamma)=0.47+/-0.66 KeV, Gamma(f(1370)->gamma gamma)=0.07+/-0.15 KeV,
Gamma(f(1500)->gamma gamma)=0.74+/-0.78 KeV.Comment: 6 pages, 1 figur
VLA Detection of the Ionized Stellar Winds Arising from Massive Stars in the Galactic Center Arches Cluster
The Galactic center Arches stellar cluster, detected and studied until now
only in the near-infrared, is comprised of at least one hundred massive (M>20
Msun) stars. Here we report the detection at centimeter wavelengths of radio
continuum emission from eight radio sources associated with the cluster. Seven
of these radio sources have rising spectral indices between 4.9 and 8.5 GHz and
coincide spatially with the brightest stars in the cluster, as determine from
JHK photometry and Brackett alpha and Brackett Gamma spectroscopy. Our results
confirm the presence of powerful ionized winds in these stars. The eighth radio
source has a nonthermal spectrum and its nature is yet unclear, but it could be
associated with a lower mass young star in the cluster.Comment: 6 pages, 2 embedded figures, accepted to ApJLetter
A novel MLSD receiver architecture for nonlinear channels
A new architecture for maximum likelihood sequence detec- tion (MLSD) in nonlinear dispersive channels (NLCs) is presented, and its robustness to inaccurate channel knowledge is analyzed. This architecture is developed by considering a novel orthogonal representation of the NLC, which is exploited to develop a front-end capable of obtaining uncorrelated symbol rate samples, representing a sufficient statistic for information decoding. This front-end is a special form of space-time whitened matched filter (ST-WMF), and the MLSD obtained by using this front-end (ST-WMF-MLSD) requires simple branch metrics due to the signal whitening. The ST-WMF also allows for space-time compression of the equivalent channel, which is exploited for further complexity reduction of the ST-WMF-MLSD. Simulation results show the good trade-off in performance and complexity obtained with the ST-WMF- MLSD, even in the presence of inaccurate channel knowledge.Sociedad Argentina de Informática e Investigación Operativa (SADIO
- …