2,219 research outputs found
Adaptive Cluster Expansion for Inferring Boltzmann Machines with Noisy Data
We introduce a procedure to infer the interactions among a set of binary
variables, based on their sampled frequencies and pairwise correlations. The
algorithm builds the clusters of variables contributing most to the entropy of
the inferred Ising model, and rejects the small contributions due to the
sampling noise. Our procedure successfully recovers benchmark Ising models even
at criticality and in the low temperature phase, and is applied to
neurobiological data.Comment: Accepted for publication in Physical Review Letters (2011
Generalized Chaplygin Gas Model: Dark Energy - Dark Matter Unification and CMBR Constraints
The generalized Chaplygin gas (GCG) model allows for an unified description
of the recent accelerated expansion of the Universe and the evolution of energy
density perturbations. This dark energy - dark matter unification is achieved
through an exotic background fluid whose equation of state is given by , where is a positive constant and .
Stringent constraints on the model parameters can be obtained from recent WMAP
and BOOMERanG bounds on the locations of the first few peaks and troughs of the
Cosmic Microwave Background Radiation (CMBR) power spectrum as well as SNe Ia
data.Comment: 9 pages, 2 figures; essay selected for an honorable mention by the
Gravity Research Foundation, 200
A Curvature Principle for the interaction between universes
We propose a Curvature Principle to describe the dynamics of interacting
universes in a multi-universe scenario and show, in the context of a simplified
model, how interaction drives the cosmological constant of one of the universes
toward a vanishingly small value. We also conjecture on how the proposed
Curvature Principle suggests a solution for the entropy paradox of a universe
where the cosmological constant vanishes.Comment: Essay selected for an honorable mention by the Gravity Research
Foundation, 2007. Plain latex, 8 page
Scale Factor Duality: A Quantum Cosmological Approach
We consider the minisuperspace model arising from the lowest order string
effective action containing the graviton and the dilaton and study solutions of
the resulting Wheeler-Dewitt equation. The scale factor duality symmetry is
discussed in the context of our quantum cosmological model.Comment: 10 pages, plain tex, uses panda.tex (appended
Instabilities in neutrino-plasma density waves
One examines the interaction and possible resonances between supernova
neutrinos and electron plasma waves. The neutrino phase space distribution and
its boundary regions are analyzed in detail. It is shown that the boundary
regions are too wide to produce non-linear resonant effects. The growth or
damping rates induced by neutrinos are always proportional to the neutrino flux
and .Comment: 9 pages, a few words modified to match PRD publicatio
Interacting Cosmic Fluids in Brans-Dicke Cosmology
We provide a detailed description for power-law scaling FRW cosmological
models in Brans-Dicke theory dominated by two interacting fluid components
during the expansion of the universe.Comment: 13 pages, 8 figure
Classical Nambu-Goldstone fields
It is shown that a Nambu-Goldstone (NG) field may be coherently produced by a
large number of particles in spite of the fact that the NG bosons do not couple
to flavor conserving scalar densities like . If a flavor
oscillation process takes place the phases of the pseudo-scalar or flavor
violating densities of different particles do not necessarily cancel each
other. The NG boson gets a macroscopic source whenever the total (spontaneously
broken) quantum number carried by the source particles suffers a net increase
or decrease in time. If the lepton numbers are spontaneously broken such
classical NG (majoron) fields may significantly change the neutrino oscillation
processes in stars pushing the observational capabilities of neutrino-majoron
couplings down to GeV.Comment: 11 pages, updated, to appear in PR
A New Variable Modified Chaplygin Gas Model Interacting with Scalar Field
In this letter we present a new form of the well known Chaplygin gas model by
introducing inhomogeneity in the EOS. This model explains crossing.
Also we have given a graphical representation of the model using
parameters. We have also considered an interaction of this model with the
scalar field by introducing a phenomenological coupling function and have shown
that the potential decays with time.Comment: 7 pages, 3 figure
Comportamento de recĂłpula de fĂȘmeas selvagens de Ceratitis capitata (Diptera: Tephritidae) no Vale do SĂŁo Francisco.
Moscas-das-frutas sĂŁo pragas quarentenĂĄrias relevantes na fruticultura mundial. Amosca-do-mediterrĂąneo, Ceratitis capitata Ă© cosmopolita e atualmente, a mais representativa da famĂlia Tephritidae no SubmĂ©dio do Vale do SĂŁo Francisco (VSF), no Nordeste do Brasil.Resumo 1003-1
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