27,647 research outputs found
Power-law statistics and stellar rotational velocities in the Pleiades
In this paper we will show that, the non-gaussian statistics framework based
on the Kaniadakis statistics is more appropriate to fit the observed
distributions of projected rotational velocity measurements of stars in the
Pleiades open cluster. To this end, we compare the results from the
and -distributions with the Maxwellian.Comment: 13 pages, 3 figure
Non-linear Poisson-Boltzmann Theory for Swollen Clays
The non-linear Poisson-Boltzmann equation for a circular, uniformly charged
platelet, confined together with co- and counter-ions to a cylindrical cell, is
solved semi-analytically by transforming it into an integral equation and
solving the latter iteratively. This method proves efficient, robust, and can
be readily generalized to other problems based on cell models, treated within
non-linear Poisson-like theory. The solution to the PB equation is computed
over a wide range of physical conditions, and the resulting osmotic equation of
state is shown to be in fair agreement with recent experimental data for
Laponite clay suspensions, in the concentrated gel phase.Comment: 13 pages, 4 postscript figure
Environments of Redshift Survey Compact Groups of Galaxies
Redshift Survey Compact Groups (RSCGs) are tight knots of N >= 3 galaxies
selected from the CfA2+SSRS2 redshift survey. The selection is based on
physical extent and association in redshift space alone. We measured 300 new
redshifts of fainter galaxies within 1 h^{-1} Mpc of 14 RSCGs to explore the
relationship between RSCGs and their environments. 13 of 14 RSCGs are embedded
in overdense regions of redshift space. The systems range from a loose group of
5 members to an Abell cluster. The remaining group, RSCG 64, appears isolated.
RSCGs are isolated and distinct from their surroundings to varying degrees, as
are the Hickson Compact Groups. Among the 13 embedded RSCGs, 3 are distinct
from their general environments (RSCG 9, RSCG 11 and RSCG 85).Comment: 35 pages, including 10 figures and 5 tables, accepted for publication
in the Astronomical Journa
Amostragem de solo em plantio direto para aplicação em agricultura de precisão.
O objetivo deste estudo seria a comparação das diversas técnicas estatísticas disponíveis, visando o estudo da amostragem de solo para plantio direto. Com a formação de bases de dados digitais e melhores métodos para coleção de dados e análise geoestatfstica, estudos mais detalhados podem ser realizados sobre a variação dos solos e suas conseqüências.bitstream/item/76078/1/CNPTIA-PESQ.AND.-1-99.pd
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
Relações hídricas de gravioleiras (Annona muricata L.) jovens em porta-enxertos dos gêneros Annona e Rollinia.
Publicado também: FRAZÃO, D. A. C.; HOMMA, A. K. O; VIÉGAS, I. de J. M. (Ed.). Contribuição ao desenvolvimento da fruticultura na Amazônia. Belém, PA: Embrapa Amazônia Oriental, 2006. p. 543-548
Data-Mining a Large Digital Sky Survey: From the Challenges to the Scientific Results
The analysis and an efficient scientific exploration of the Digital Palomar
Observatory Sky Survey (DPOSS) represents a major technical challenge. The
input data set consists of 3 Terabytes of pixel information, and contains a few
billion sources. We describe some of the specific scientific problems posed by
the data, including searches for distant quasars and clusters of galaxies, and
the data-mining techniques we are exploring in addressing them.
Machine-assisted discovery methods may become essential for the analysis of
such multi-Terabyte data sets. New and future approaches involve unsupervised
classification and clustering analysis in the Giga-object data space, including
various Bayesian techniques. In addition to the searches for known types of
objects in this data base, these techniques may also offer the possibility of
discovering previously unknown, rare types of astronomical objects.Comment: Invited paper, to appear in Applications of Digital Image Processing
XX, ed. A. Tescher, Proc. S.P.I.E. vol. 3164, in press; 10 pages, a
self-contained TeX file, and 3 separate postscript figure
Validação de modelos geoestatísticos usando teste de Filliben: aplicação em agroclimatologia.
O objetivo deste trabalho é validar modelos geoestatísticos aplicados a agroclimatologia através do teste de normalidade de Filliben em resíduos ortonormais com dados de precipitação média anual para o Estado de São Paulo.bitstream/CNPTIA/10388/1/comtec60.pdfAcesso em: 28 maio 2008
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