2,407 research outputs found
Convex Neighbourhoods and Complete Finsler Spaces
In this paper, it is shown that a large set of connections on a suitable
sub-bundle of the tangent bundle of a Finsler Manifold can be used to study all
the properties of convex neighbourhoods with respect to the Finsler Metric,
which are needed to see that any Complete Finsler Space is Geodesically
Connected.Comment: 17 page
Gravitational clustering in N-body simulations
In this talk we discuss some of the main theoretical problems in the
understanding of the statistical properties of gravity. By means of N-body
simulations we approach the problem of understanding the r\^ole of gravity in
the clustering of a finite set of N-interacting particles which samples a
portion of an infinite system. Through the use of the conditional average
density, we study the evolution of the clustering for the system putting in
evidence some interesting and not yet understood features of the process.Comment: 5 pages, 1 figur
Clustering in N-Body gravitating systems
Self-gravitating systems have acquired growing interest in statistical
mechanics, due to the peculiarities of the 1/r potential. Indeed, the usual
approach of statistical mechanics cannot be applied to a system of many point
particles interacting with the Newtonian potential, because of (i) the long
range nature of the 1/r potential and of (ii) the divergence at the origin. We
study numerically the evolutionary behavior of self-gravitating systems with
periodical boundary conditions, starting from simple initial conditions. We do
not consider in the simulations additional effects as the (cosmological) metric
expansion and/or sophisticated initial conditions, since we are interested
whether and how gravity by itself can produce clustered structures. We are able
to identify well defined correlation properties during the evolution of the
system, which seem to show a well defined thermodynamic limit, as opposed to
the properties of the ``equilibrium state''.
Gravity-induced clustering also shows interesting self-similar
characteristics.Comment: 6 pages, 5 figures. To be published on Physica
Spillover and diffraction sidelobe contamination in a double-shielded experiment for mapping Galactic synchrotron emission
We have analyzed observations from a radioastronomical experiment to survey
the sky at decimetric wavelengths along with feed pattern measurements in order
to account for the level of ground contamination entering the sidelobes. A
major asset of the experiment is the use of a wire mesh fence around the
rim-halo shielded antenna with the purpose of levelling out and reducing this
source of stray radiation for zenith-centered 1-rpm circular scans. We
investigate the shielding performance of the experiment by means of a geometric
diffraction model in order to predict the level of the spillover and
diffraction sidelobes in the direction of the ground. Using 408 MHz and 1465
MHz feed measurements, the model shows how a weakly-diffracting and unshielded
antenna configuration becomes strongly-diffracting and double-shielded as
far-field diffraction effects give way to near-field ones. Due to the
asymmetric response of the feeds, the orientation of their radiation fields
with respect to the secondary must be known a priori before comparing model
predictions with observational data. By adjusting the attenuation coefficient
of the wire mesh the model is able to reproduce the amount of differential
ground pick-up observed during test measurements at 1465 MHz.Comment: 14 pages, 17 eps + 1 gif figures and 4 Tables. Accepted for
publication in A&AS. Fig.7 available at full resolution from
http://www.das.inpe.br/~tello/publications.ht
Perfil sócio-econômico dos alunos da creche Irmã Anísia Rocha da cidade de Sobral, CE no ano de 2005.
O estudo é parte do projeto "Manipulação de constituintes e prospecção de propriedades funcionais do leite de cabra" financiado pelo Macroprograma 2 da Embrapa e, liderado pela Embrapa Caprinos, que teve objetivo geral: Conhecer o efeito de estratégias nutricionais para manipulação do perfil de caseínas e de ácidos graxos do leite de cabra e seus impactos sobre a saúde humana na prospecção de propriedades funcionais. Além de conhecer melhor o aluno, trata-se de gerar subsídios para melhorar a qualidade do ensino e prestação de serviços pela Creche Irmã Anísia Rocha.bitstream/CNPC/20815/1/cot84.pd
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