27,658 research outputs found
Optimal network topologies for information transmission in active networks
This work clarifies the relation between network circuit (topology) and
behavior (information transmission and synchronization) in active networks,
e.g. neural networks. As an application, we show how to determine a network
topology that is optimal for information transmission. By optimal, we mean that
the network is able to transmit a large amount of information, it possesses a
large number of communication channels, and it is robust under large variations
of the network coupling configuration. This theoretical approach is general and
does not depend on the particular dynamic of the elements forming the network,
since the network topology can be determined by finding a Laplacian matrix (the
matrix that describes the connections and the coupling strengths among the
elements) whose eigenvalues satisfy some special conditions. To illustrate our
ideas and theoretical approaches, we use neural networks of electrically
connected chaotic Hindmarsh-Rose neurons.Comment: 20 pages, 12 figure
The Role of Fermions in Bubble Nucleation
We present a study of the role of fermions in the decay of metastable states
of a scalar field via bubble nucleation. We analyze both one and
three-dimensional systems by using a gradient expansion for the calculation of
the fermionic determinant. The results of the one-dimensional case are compared
to the exact results of previous work.Comment: 15 pages, revtex, 9 figure
InfluĂȘncia do espaçamento nas caracterĂsticas fĂsico-mecĂąnicas da madeira de Bagassa guianensis Aubl. (Tatajuba) no planalto de Belterra, ParĂĄ.
bitstream/item/59284/1/CPATU-ComTec88.pd
Holonomy Transformation in the FRW Metric
In this work we investigate loop variables in Friedman-Robertson-Walker
spacetime. We analyze the parallel transport of vectors and spinors in several
paths in this spacetime in order to classify its global properties. The band
holonomy invariance is analysed in this background.Comment: 8 page
Weak measurement og the composite Goo-Haenchen shift in the critical region
By using a weak measurement technique, we investigated the interplay between
the angular and lateral Goos-Haenchen shift of a focused He-Ne laser beam for
incidence near the critical angle. We verified that this interplay dramatically
affects the composite Goos-Haenchen shift of the propagated beam. The
experimental results confirm theoretical predictions that recently appeared in
the literature.Comment: 10 pages, 3 figure
Experimental evidence of laser power oscillations induced by the relative Fresnel (Goos-Haenchen) phase
The amplification of the relative Fresnel (Goos-Haenchen) phase by an
appropriate number of total internal reflections and the choice of favorable
incidence angles allow to observe full oscillations in the power of a DPSS
laser transmitted through sequential BK7 blocks. The experimental results
confirm the theoretical predictions. The optical apparatus used in this letter
can be seen as a new type of two-phase ellipsometric system where the phase of
the complex refractive index is replaced by the relative Fresnel
(Goos-Haenchen) phase.Comment: 7 pages, 3 figures, 1 tabl
Deformed Gaussian Orthogonal Ensemble description of Small-World networks
The study of spectral behavior of networks has gained enthusiasm over the
last few years. In particular, Random Matrix Theory (RMT) concepts have proven
to be useful. In discussing transition from regular behavior to fully chaotic
behavior it has been found that an extrapolation formula of the Brody type can
be used. In the present paper we analyze the regular to chaotic behavior of
Small World (SW) networks using an extension of the Gaussian Orthogonal
Ensemble. This RMT ensemble, coined the Deformed Gaussian Orthogonal Ensemble
(DGOE), supplies a natural foundation of the Brody formula. SW networks follow
GOE statistics till certain range of eigenvalues correlations depending upon
the strength of random connections. We show that for these regimes of SW
networks where spectral correlations do not follow GOE beyond certain range,
DGOE statistics models the correlations very well. The analysis performed in
this paper proves the utility of the DGOE in network physics, as much as it has
been useful in other physical systems.Comment: Replaced with the revised version, accepted for publication in Phys.
Rev.
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