26,870 research outputs found
Building a Sample of Distant Clusters of Galaxies
Candidate clusters of galaxies drawn from the sample identified from the
moderately deep I-band data of the ESO Imaging Survey (EIS), have been used for
follow-up optical/infrared imaging and spectroscopic observations. The
observations were conducted to assess the nature of these candidates over a
large range of redshifts. Currently, 163 EIS candidates have (V-I) colors, 15
have (I-K) and 65 cluster fields have been observed spectroscopically. From a
preliminary analysis of these data, we find that > 65% of the candidates
studied show strong evidence of being real physical associations, over the
redshift range 0.2<z<1.1. The evidence in some cases comes directly from
spectroscopic measurements, in others indirectly from the detection of
overdensities of objects with either the same color or the same photometric
redshift, or from a combination of color and spectroscopic information.
Preliminary results also suggest that the redshift derived from the
matched-filter algorithm is a reasonable measure of the cluster's redshift,
possibly overestimating it by Delta z ~0.1, at least for systems at z<0.7.
Overdensities of red objects have been detected in over 100 candidates, 38 of
which with estimated redshifts >0.6, and six candidates in the interval
0.45<z<0.81 have either been identified directly from measured redshifts or
have been confirmed by the measurement of at least one redshift for galaxies
located along a red-sequence typical of cluster early-type galaxies. Lastly,
five candidates among those already observed in the infrared have (I-Ks) colors
consistent with them being in the redshift interval 0.8<z<1.1. The sample of
"confirmed" clusters, already the largest of its kind in the southern
hemisphere, will be further enlarged by ongoing observations.Comment: To appear in "Large Scale Structure in the X-ray Universe", ed. M.
Plionis and I. Georgantopoulos (Paris: Editions Frontieres), in pres
Análise comparativa do meio físico e socioeconômico de três municípios com parques florestais: Araponga, Caparaó e São Roque de Minas - MG.
O meio físico, a localização geográfica, e a história de ocupação de um município contribuem na sua socioeconomia. Do mesmo modo, limitações físicas naturais resultam em pouca alteração antrópica, protegendo áreas que podem vir a ser transformadas em unidades de conservação, sob leis de proteção ambiental. Estas áreas, como por exemplo, parques florestais, apresentam potencial turístico, como uma alternativa socioeconômica. Este trabalho é uma análise comparativa de informações municipais socioeconômicas, históricas e do meio físico, com o objetivo de investigar uma possível influência de parques florestais na socioeconomia de municípios do Estado de Minas Gerais que contém grande parte de suas áreas com topografia acidentada e altitude elevada. Foram selecionados os municípios de Araponga, com o Parque Estadual da Serra do Brigadeiro, recém criado em 1996; Caparaó, com o Parque Nacional de Caparaó, criado em 1962; e São Roque de Minas, com o Parque Nacional da Serra da Canastra, criado em 1972. São Roque de Minas e Caparaó são Municípios tradicionalmente incluídos na rede turística, o que pode vir a ocorrer com Araponga futuramente. Os resultados mostram que os municípios de Araponga e Caparaó apresentam restrição topográfica, enquanto que as maiores limitações de São Roque são devidas ao solo. Historicamente, a formação de Araponga é semelhante a de Caparaó, em ocupação. Com relação a localização geográfica, Araponga está melhor situada que São Roque de Minas em distância dos grandes centros, mas as condições de acesso são similares. Considerando a socioeconomia, Araponga tem maiores índices de analfabetismo, evasão populacional, menor ICM, menores salários, e pior distribuição de renda. Enfocando o turismo em Caparaó e São Roque de Minas, as taxas de visitação atingiram 28.613 pessoas para o ano de 1999 em Caparaó, correspondendo a mais de 400% da população, e 3.000 pessoas/ano em São Roque de Minas (IBAMA, 1993), que corresponde a 52% da população. Embora não conclusivo, indica-se, pelas informações levantadas, que as piores condições socioeconômicas de Araponga em relação a Caparaó se devam à situação geográfica e a contribuição turística na economia de Caparaó. Já São Roque de Minas tem melhor desenvolvimento que Araponga e Caparaó devido à origem histórica e maior porção de terras menos acidentadas, refletindo na economia pecuária. A contribuição pelo turismo neste município é ainda modesta.bitstream/CNPS-2010/14880/1/doc-71-municipios-mg.pd
Impactos sócio-econômicos do sistema de derriça mecanizado portátil na colheita de café de montanha no Brasil.
bitstream/item/84033/1/BPD36-2012.pd
A Fast and Accurate Nonlinear Spectral Method for Image Recognition and Registration
This article addresses the problem of two- and higher dimensional pattern
matching, i.e. the identification of instances of a template within a larger
signal space, which is a form of registration. Unlike traditional correlation,
we aim at obtaining more selective matchings by considering more strict
comparisons of gray-level intensity. In order to achieve fast matching, a
nonlinear thresholded version of the fast Fourier transform is applied to a
gray-level decomposition of the original 2D image. The potential of the method
is substantiated with respect to real data involving the selective
identification of neuronal cell bodies in gray-level images.Comment: 4 pages, 3 figure
Growth-Driven Percolations: The Dynamics of Community Formation in Neuronal Systems
The quintessential property of neuronal systems is their intensive patterns
of selective synaptic connections. The current work describes a physics-based
approach to neuronal shape modeling and synthesis and its consideration for the
simulation of neuronal development and the formation of neuronal communities.
Starting from images of real neurons, geometrical measurements are obtained and
used to construct probabilistic models which can be subsequently sampled in
order to produce morphologically realistic neuronal cells. Such cells are
progressively grown while monitoring their connections along time, which are
analysed in terms of percolation concepts. However, unlike traditional
percolation, the critical point is verified along the growth stages, not the
density of cells, which remains constant throughout the neuronal growth
dynamics. It is shown, through simulations, that growing beta cells tend to
reach percolation sooner than the alpha counterparts with the same diameter.
Also, the percolation becomes more abrupt for higher densities of cells, being
markedly sharper for the beta cells.Comment: 8 pages, 10 figure
Utilité des informations et agents cognitifs
International audienceThis paper focuses on modelling information usefulness. More precisely, it aims at characterizing how useful a piece of information is for a cognitive agent which has some beliefs and goals. The paper presents three different approaches. We take Information Retrieval as a particular applicative domain and we compare some existing measures with the usefulness measure introduced here.Dans cet article, nous nous intéressons à la modélisation de l'utilité des informations. Plus précisément, nous visons à caractériser ce qu'est, pour un agent cognitif qui a des croyances et des buts, une information utile ou à quel de-gré une information lui est utile. Nous présentons trois mo-dèles différents et nous prenons la Recherche d'Informa-tion comme domaine applicatif en comparant les mesures existantes avec une mesure d'utilité définie ici
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