9,891 research outputs found
Fluctuations of a surface relaxation model in interacting scale free networks
Isolated complex networks have been studied deeply in the last decades due to
the fact that many real systems can be modeled using these types of structures.
However, it is well known that the behavior of a system not only depends on
itself, but usually also depends on the dynamics of other structures. For this
reason, interacting complex networks and the processes developed on them have
been the focus of study of many researches in the last years. One of the most
studied subjects in this type of structures is the Synchronization problem,
which is important in a wide variety of processes in real systems. In this
manuscript we study the synchronization of two interacting scale-free networks,
in which each node has dependency links with different nodes in the other
network. We map the synchronization problem with an interface growth, by
studying the fluctuations in the steady state of a scalar field defined in both
networks.
We find that as slightly increases from , there is a really
significant decreasing in the fluctuations of the system. However, this
considerable improvement takes place mainly for small values of , when the
interaction between networks becomes stronger there is only a slight change in
the fluctuations. We characterize how the dispersion of the scalar field
depends on the internal degree, and we show that a combination between the
decreasing of this dispersion and the integer nature of our growth model are
the responsible for the behavior of the fluctuations with .Comment: 11 pages, 4 figures and 1 tabl
On the void explanation of the Cold Spot
The integrated Sachs-Wolfe (ISW) contribution induced on the cosmic microwave
background by the presence of a supervoid as the one detected by Szapudi et al.
(2015) is reviewed in this letter in order to check whether it could explain
the Cold Spot (CS) anomaly. Two different models, previously used for the same
purpose, are considered to describe the matter density profile of the void: a
top hat function and a compensated profile produced by a Gaussian potential.
The analysis shows that, even enabling ellipticity changes or different values
for the dark-energy equation of state parameter , the ISW contribution
due to the presence of the void does not reproduce the properties of the CS.
Finally, the probability of alignment between the void and the CS is also
questioned as an argument in favor of a physical connection between these two
phenomena
Orbits for eighteen visual binaries and two double-line spectroscopic binaries observed with HRCAM on the CTIO SOAR 4m telescope, using a new Bayesian orbit code based on Markov Chain Monte Carlo
We present orbital elements and mass sums for eighteen visual binary stars of
spectral types B to K (five of which are new orbits) with periods ranging from
20 to more than 500 yr. For two double-line spectroscopic binaries with no
previous orbits, the individual component masses, using combined astrometric
and radial velocity data, have a formal uncertainty of ~0.1 MSun. Adopting
published photometry, and trigonometric parallaxes, plus our own measurements,
we place these objects on an H-R diagram, and discuss their evolutionary
status. These objects are part of a survey to characterize the binary
population of stars in the Southern Hemisphere, using the SOAR 4m
telescope+HRCAM at CTIO. Orbital elements are computed using a newly developed
Markov Chain Monte Carlo algorithm that delivers maximum likelihood estimates
of the parameters, as well as posterior probability density functions that
allow us to evaluate the uncertainty of our derived parameters in a robust way.
For spectroscopic binaries, using our approach, it is possible to derive a
self-consistent parallax for the system from the combined astrometric plus
radial velocity data ("orbital parallax"), which compares well with the
trigonometric parallaxes. We also present a mathematical formalism that allows
a dimensionality reduction of the feature space from seven to three search
parameters (or from ten to seven dimensions - including parallax - in the case
of spectroscopic binaries with astrometric data), which makes it possible to
explore a smaller number of parameters in each case, improving the
computational efficiency of our Markov Chain Monte Carlo code.Comment: 32 pages, 9 figures, 6 tables. Detailed Appendix with methodology.
Accepted by The Astronomical Journa
Finite-temperature properties of hard-core bosons confined on one-dimensional optical lattices
We present an exact study of the finite-temperature properties of hard-core
bosons (HCB's) confined on one-dimensional optical lattices. Our solution of
the HCB problem is based on the Jordan-Wigner transformation and properties of
Slater determinants. We analyze the effects of the temperature on the behavior
of the one-particle correlations, the momentum distribution function, and the
lowest natural orbitals. In addition, we compare results obtained using the
grand-canonical and canonical descriptions for systems like the ones recently
achieved experimentally. We show that even for such small systems, as small as
10 HCB's in 50 lattice sites, there are only minor differences between the
energies and momentum distributions obtained within both ensembles.Comment: RevTex file, 12 pages, 16 figures, published versio
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