12,807 research outputs found
An approach for the detection of point-sources in very high resolution microwave maps
This paper deals with the detection problem of extragalactic point-sources in
multi-frequency, microwave sky maps that will be obtainable in future cosmic
microwave background radiation (CMB) experiments with instruments capable of
very high spatial resolution. With spatial resolutions that can be of order of
0.1-1.0 arcsec or better, the extragalactic point-sources will appear isolated.
The same holds also for the compact structures due to the Sunyaev-Zeldovich
(SZ) effect (both thermal and kinetic). This situation is different from the
maps obtainable with instruments as WMAP or PLANCK where, because of the
smaller spatial resolution (approximately 5-30 arcmin), the point-sources and
the compact structures due to the SZ effect form a uniform noisy background
(the "confusion noise"). Hence, the point-source detection techniques developed
in the past are based on the assumption that all the emissions that contribute
to the microwave background can be modeled with homogeneous and isotropic
(often Gaussian) random fields and make use of the corresponding spatial
power-spectra. In the case of very high resolution observations such an
assumption cannot be adopted since it still holds only for the CMB. Here, we
propose an approach based on the assumption that the diffuse emissions that
contribute to the microwave background can be locally approximated by
two-dimensional low order polynomials. In particular, two sets of numerical
techniques are presented containing two different algorithms each. The
performance of the algorithms is tested with numerical experiments that mimic
the physical scenario expected for high Galactic latitude observations with the
Atacama Large Millimeter/Submillimeter Array (ALMA).Comment: Accepted for publication on "Astronomy & Astrophysics". arXiv admin
note: substantial text overlap with arXiv:1206.4536 Replaced version is the
accepted one and published in A&
O processamento da forma global nas perturbações do espetro do autismo
Enquanto o processamento local foi robustamente demonstrado, a literatura
diverge relativamente ao processamento global nas perturbações do espetro do autismo
(PEA). Este estudo teve como objetivo explorar a capacidade para processar informação
global, enfatizando a sua trajetória desenvolvimental, em indivíduos com PEA. Os
participantes foram avaliados em duas tarefas, utlizando objectos ecológicos, que
requeriam processos de agrupamento distintos: a primeira, envolvendo estímulos que
permitiam o recurso ora de ambas as frequências espaciais ora de frequências espaciais
baixas para agrupar; e a segunda, envolvendo estímulos que não permitiam o recurso a
frequências espaciais para agrupar. As crianças com PEA mostraram, ao contrário das
crianças com desenvolvimento típico, dificuldades em algumas formas de
processamento global mas não noutras, dependendo dos processos de agrupamento
exigidos. Os adultos com PEA mostraram um processamento global idêntico ao dos
adultos com desenvolvimento típico. Estes resultados vão de encontro às conclusões de
estudos recentes, que sugerem que o processamento global em indivíduos com PEA se
desenvolve com a idade. A discrepância na literatura sobre o processamento global nas
PEA pode, então, ser explicada pela exigência do processamento do estímulo e a etapa
de desenvolvimento dos indivíduos
First report of Puccinia thaliae causing rust on Canna spp. in Europe
Disease Notesinfo:eu-repo/semantics/publishedVersio
Efeitos da semicarbazida no esqueleto de ratos Wistar em crescimento.
The effects of semicarbazide hydrochloride on skeletal tissues were evaluated using Wistar rats. In the animals submitted to the administration of semicarbazide, radiological examination showed bone and articular alterations with growth plates enlargement. Histological exams showed irregular patterns and proliferation of chondrocytes and excessive accumulation of extracellular matrix. Immunohistochemical exams showed PCNA positive reaction in pre- and hypertrofic chondrocytes. These results confirm that semicarbazide induces important changes in skeletal tissues and that has potential utility in experimental osteolathryrism
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