6,097 research outputs found
Dynamic Scaling of Non-Euclidean Interfaces
The dynamic scaling of curved interfaces presents features that are
strikingly different from those of the planar ones. Spherical surfaces above
one dimension are flat because the noise is irrelevant in such cases. Kinetic
roughening is thus a one-dimensional phenomenon characterized by a marginal
logarithmic amplitude of the fluctuations. Models characterized by a planar
dynamical exponent , which include the most common stochastic growth
equations, suffer a loss of correlation along the interface, and their dynamics
reduce to that of the radial random deposition model in the long time limit.
The consequences in several applications are discussed, and we conclude that it
is necessary to reexamine some experimental results in which standard scaling
analysis was applied
Alignment tests for low CMB multipoles
We investigate the large scale anomalies in the angular distribution of the
cosmic microwave background radiation as measured by WMAP using several tests.
These tests, based on the multipole vector expansion, measure correlations
between the phases of the multipoles as expressed by the directions of the
multipole vectors and their associated normal planes. We have computed the
probability distribution functions for 46 such tests, for the multipoles l=2-5.
We confirm earlier findings that point to a high level of alignment between l=2
(quadrupole) and l=3 (octopole), but with our tests we do not find significant
planarity in the octopole. In addition, we have found other possible anomalies
in the alignment between the octopole and the l=4 (hexadecupole) components, as
well as in the planarity of l=4 and l=5. We introduce the notion of a total
likelihood to estimate the relevance of the low-multipoles tests of
non-gaussianity. We show that, as a result of these tests, the CMB maps which
are most widely used for cosmological analysis lie within the ~ 10% of randomly
generated maps with lowest likelihoods.Comment: References added, updated discussion on alignment with Ecliptic
Plane. 12 Pages, 6 Figures. Results for additional maps, the normalized
frequencies for the tests and a Mathematica Notebook that computes the tests
can be found on http://fma.if.usp.br/~abramo/MVA.htm
Classical solutions for the Carroll-Field-Jackiw-Proca electrodynamics
In the present work, we investigate classical solutions of the
Maxwell-Carroll-Field-Jackiw-Proca (MCFJP) electrodynamics for the cases a
purely timelike and spacelike Lorentz-violating (LV) background. Starting from
the MCFJP Lagrangian and the associated wave equations written for the
potential four-vector, the tensor form of the Green function is achieved. In
the timelike case, the components of the stationary Green function are
explicitly written. The classical solutions for the electric and magnetic field
strengths are then evaluated, being observed that the electric sector is not
modified by the LV background, keeping the Maxwell-Proca behavior. The magnetic
field associated with a charge in uniform motion presents an oscillating
behavior that also provides an oscillating MCFJ solution (in the limit of a
vanishing Proca mass), but does not recover the Maxwell-Proca solution in the
limit of vanishing background. In the spacelike case, the stationary Green
function is written and also explicitly carried out in the regime of a small
background. The electric and magnetic fields reveal to possess an exponentially
decaying behavior, that recover the Maxwell-Proca solutions.Comment: 14 rextex4 pages; 2 figures; minimal changes in abstract and
introduction; added reference
Musical Auditory Stimulation and Cardiac Autonomic Regulation
Previous studies have already demonstrated that auditory stimulation with music influences the cardiovascular system. In this study, we described the relationship between musical auditory stimulation and heart rate variability. Searches were performed with the Medline, SciELO, Lilacs and Cochrane databases using the following keywords: “auditory stimulation”, “autonomic nervous system”, “music” and “heart rate variability”. The selected studies indicated that there is a strong correlation between noise intensity and vagal-sympathetic balance. Additionally, it was reported that music therapy improved heart rate variability in anthracycline-treated breast cancer patients. It was hypothesized that dopamine release in the striatal system induced by pleasurable songs is involved in cardiac autonomic regulation. Musical auditory stimulation influences heart rate variability through a neural mechanism that is not well understood. Further studies are necessary to develop new therapies to treat cardiovascular disorders
Cooperação orientada Ă produção de conhecimento cientĂfico
O termo e conceito cooperação tem vindo a ocupar cada vez mais e com
maior ênfase os espaços noticiosos e de debate, sustentando a rede de projectos
que se sucedem um pouco por todo o planeta, com fim à construção de uma “casa
comum” onde, como nas grandes famĂlias, as aprendizagens matriciais passam pelo
“aprender a viver juntos”, “aprender a aprender juntos” e “aprender a crescer
juntos”, princĂpios de globalização planetária
Assessing the quality of the relation between scalarizing function parameters and solutions in multiobjective optimization
Different Multi-Objective Optimization Methods
(MOOM) for solving Multi-Objective Optimization Problems
(MOOP) have been suggested in the literature. These methods
often comprise two stages (not necessarily sequential): i) the
search for the Pareto-optimal set and ii) the selection of a single
solution from this non-dominated set. Various studies
comparing performance of particular aspects of these methods
have been carried out. However, a theoretical support that
changes on the preferences of a Decision Maker (DM) will be
reflected in the same way on the solution of the MOOP given by
the MOOM has not been presented. In this work a consistency
measure to assess MOOM is proposed. It will used to compare
the performance of different methods available in the
literature. This study was performed using some benchmark
test problems, with two criteria.This work was supported in part by the Portuguese Fundacao para a Ciencia e Tecnologia under grants: PTDC/GES/70168/2006 and SFRH/BD/22808/2005
(Oligo)thienyl-imidazo-benzocrown ether derivatives : synthesis, photophysical studies and evaluation of their chemosensory properties
A series of novel (oligo)thienyl-imidazobenzocrown ethers were synthesised through a simple method and evaluated as fluorimetric chemosensors for transition metal cations. Interaction with Ni2+, Pd2+, and Hg2+ in ACN/DMSO solution (99:1) was studied by absorption and emission spectroscopy. Chemoselectivity studies in the presence of Na+ were also carried out and a fluorescence enhancement upon chelation (CHEF) effect was observed following Hg2+ complexation. Considering that most systems using fluorescence spectroscopy for detecting Hg2+ are based on the complexation enhancement of the fluorescence quenching (CHEQ) effect, the present work represents one of the few examples for sensing of Hg2+ based on a CHEF effect.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/QUI/66250/2006, SFRH/BD/36396/2007, SRFH/BPD/72557/201
Sward Structural Characteristics of Perennial Peanut Genotypes as Affected by Harvest Frequency
Despite the high potential of tropical forage species, herbage production, nutritive value and animal productivity in Brazilian livestock production systems are lower than what can be obtained from both a biological and operational point of view (Pedreira and Mello 2000, Da Silva and Sbrissia 2000). Even with these limitations, the livestock industry is often able to sustain high productivity levels (animal product per hectare) by using good animal genetics and supplementation. Reducing production costs, however, will likely depend on the identification and incorporation of a high-quality forage resource, in terms of both improving diet quality of grazing animals and sustaining pasture soil productivity. The search for economically viable and sustainable forage production alternatives has been the subject of a great deal of research in many parts of the world. Among the alternatives explored, the diversification of pastures by the introduction of forage legumes in traditional production systems has been suggested, mainly to improve soil chemical characteristics (increased nitrogen levels) and improve forage quality (Perez 2004, Valentim and Andrade 2004). Promising legume germplasm is available in the tropics, but before these materials are incorporated into commercial systems, they need to be evaluated for adaptation, productivity and persistence in specific micro-environments. In addition, interactions involving grazing management strategies and genotypes should be described and explained, so that their agronomic potential can be explored.
The aim of this study was to characterise sward structure of 4 perennial peanut genotypes subjected to 2 harvest management strategies, in south-eastern Brazil
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