20,648 research outputs found
Fractionally Integrated Moving Average Stable Processes With Long-Range Dependence
Long memory processes driven by L\'evy noise with finite second-order moments
have been well studied in the literature. They form a very rich class of
processes presenting an autocovariance function which decays like a power
function. Here, we study a class of L\'evy process whose second-order moments
are infinite, the so-called -stable processes. Based on Samorodnitsky
and Taqqu (2000), we construct an isometry that allows us to define stochastic
integrals concerning the linear fractional stable motion using
Riemann-Liouville fractional integrals. With this construction, follows
naturally an integration by parts formula. We then present a family of
stationary processes with the property of long-range dependence,
using a generalized measure to investigate its dependence structure. In the
end, the law of large number's result for a time's sample of the process is
shown as an application of the isometry and integration by parts formula
Atrasos Pubertários. Considerações a Propósito da CasuÃstica de uma Consulta de Endocrinologia Pediátrica
Os autores fizeram a revisão retrospectiva de 65 processos de jovens enviados à Consulta de Endocrinologia Pediátrica por atraso pubertário durante um perÃodo de 10 anos. O diagnóstico foi confirmado em 27 jovens e em 38 a observação e a evolução permitiram demonstrar que aquele não existia. Nos doentes com atraso pubertário, a idade média de referência à consulta foi 14,6 ± 3,3 anos
(média ± DP) e o tempo médio de seguimento foi 3,2 ± 3,0 anos. Os doentes com atraso pubertário comprovado dividiram-se por
3 grupos etiológicos: hipogonadismo temporário incluindo o atraso constitucional de maturação e anemias crónicas; situações hipergonadotróficas e hipogonadotróficas permanentes. Analisaram-se as caracterÃsticas de cada grupo etiológico. Em 5 casos de
hipogonadismo temporário e em 7 de condições permanentes foi feito tratamento; a idade cronológica e a idade óssea médias no inÃcio da terapêutica eram 17,4 ± 2,5 anos e 12,9 ± 1,3 anos respectivamente. Os autores concluem, de acordo com literatura recente, pela
necessidade de referência e tratamento mais precoce destes doentes
Critical points of the Black-Hole potential for homogeneous special geometries
We extend the analysis of N=2 extremal Black-Hole attractor equations to the
case of special geometries based on homogeneous coset spaces. For non-BPS
critical points (with non vanishing central charge) the (Bekenstein-Hawking)
entropy formula is the same as for symmetric spaces, namely four times the
square of the central charge evaluated at the critical point. For non
homogeneous geometries the deviation from this formula is given in terms of
geometrical data of special geometry in presence of a background symplectic
charge vector.Comment: 17 pages, LaTeX fil
Nambu monopoles interacting with lattice defects in two-dimensional artificial square spin ice
The interactions between an excitation (similar to a pair of Nambu monopoles)
and a lattice defect are studied in an artificial two-dimensional square spin
ice. This is done by considering a square array of islands containing only one
island different from all others. This difference is incorporated in the
magnetic moment (spin) of the "imperfect" island and several cases are studied,
including the special situation in which this distinct spin is zero (vacancy).
We have shown that the two extreme points of a malformed island behave like two
opposite magnetic charges. Then, the effective interaction between a pair of
Nambu monopoles with the deformed island is a problem involving four magnetic
charges (two pairs of opposite poles) and a string. We also sketch the
configuration of the field lines of these four charges to confirm this picture.
The influence of the string on this interaction decays rapidly with the string
distance from the defect.Comment: 7 pages, 13 figure
Plantio comprobatório de canjarana (Cabralea canjerana subsp. canjerana).
bitstream/item/101394/1/PA-1999-Carvalho-PlantioComprobatorio.pd
Non-parametric comparison of histogrammed two-dimensional data distributions using the Energy Test
When monitoring complex experiments, comparison is often made between regularly acquired histograms of data and reference histograms which represent the ideal state of the equipment. With the larger HEP experiments now ramping up, there is a need for automation of this task since the volume of comparisons could overwhelm human operators. However, the two-dimensional histogram comparison tools available in ROOT have been noted in the past to exhibit shortcomings. We discuss a newer comparison test for two-dimensional histograms, based on the Energy Test of Aslan and Zech, which provides more conclusive
discrimination between histograms of data coming from different distributions than methods provided in a recent ROOT release.The Science and Technology Facilities Council, U
Determination of the mating system of tucumã palm using microsatellite markers.
A palmeira Astrocaryum aculeatum produz frutos comestÃveis, utilizados na alimentação por populações indÃgenas, tradicionais e urbanas. Esta espécie é incipientemente domesticada e pouco estudada apesar de sua importância econômica para pequenos produtores e extrativistas. Estudos do sistema reprodutivo são necessários para conservação e uso dos recursos genéticos da espécie. O objetivo foi estimar parâmetros do sistema reprodutivo do tucumã-do-Amazonas usando marcadores microssatélites
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