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

Fast Community Identification by Hierarchical Growth

A new method for community identification is proposed which is founded on the analysis of successive neighborhoods, reached through hierarchical growth from a starting vertex, and on the definition of communities as a subgraph whose number of inner connections is larger than outer connections. In order to determine the precision and speed of the method, it is compared with one of the most popular community identification approaches, namely Girvan and Newman's algorithm. Although the hierarchical growth method is not as precise as Girvan and Newman's method, it is potentially faster than most community finding algorithms.Comment: 6 pages, 5 figure

PAIRWISE VELOCITIES OF GALAXIES IN THE CFA AND SSRS2 REDSHIFT SURVEYS

(compressed version) We combine the CfA Redshift Survey (CfA2) and the Southern Sky Redshift Survey (SSRS2) to estimate the pairwise velocity dispersion of galaxies \sig12 on a scale of \sim 1 \hmpc. Both surveys are complete to an apparent magnitude limit $B(0)=15.5$. Our sample includes 12,812 galaxies distributed in a volume 1.8 \times 10^6 \hmpc3. We conclude: 1) The pairwise velocity dispersion of galaxies in the combined CfA2+SSRS2 redshift survey is \sig12=540 \kms \pm 180 \kms. Both the estimate and the variance of \sig12 significantly exceed the canonical values \sig12=340 \pm40 measured by Davis \& Peebles (1983) using CfA1. 2) We derive the uncertainty in \sig12 from the variation among subsamples with volumes on the order of $7 \times 10^5$ \hmpc3. This variation is nearly an order of magnitude larger than the formal error, 36 \kms, derived using least-squares fits to the CfA2+SSRS2 correlation function. This variation among samples is consistent with the conclusions of Mo \etal (1993) for a number of smaller surveys and with the analysis of CfA1 by Zurek \etal (1994). 3) When we remove Abell clusters with $R\ge1$ from our sample, the pairwise velocity dispersion of the remaining galaxies drops to 295 \pm 99 \kms. Thus the dominant source of variance in \sig12 is the shot noise contributed by dense virialized systems. 4) The distribution of pairwise velocities is consistent with an isotropic exponential with velocity dispersion independent of scale.Comment: 61 pages uuencoded, compressed postscript in 5 pieces. Also available in one piece at http://www.dao.nrc.ca/DAO/SCIENCE/science.htm

The Power Spectrum of Galaxies in the Nearby Universe

We compute the power spectrum of galaxy density fluctuations in a recently completed redshift survey of optically-selected galaxies in the southern hemisphere (SSRS2). The amplitude and shape of the SSRS2 power spectrum are consistent with results of the Center for Astrophysics redshift survey of the northern hemisphere (CfA2), including the abrupt change of slope on a scale of 30-50Mpc/h; these results are reproducible for independent volumes of space and variations are consistent with the errors estimated from mock surveys. Taken together, the SSRS2 and CfA2 form a complete sample of 14,383 galaxies which covers one-third of the sky. The power spectrum of this larger sample continues to rise on scales up to ~ 200Mpc/h, with weak evidence for flattening on the largest scales. The SSRS2+CfA2 power spectrum and the power spectrum constraints implied by COBE are well-matched by an Omega*h ~ 0.2, Omega+lambda_0=1 CDM model with minimal biasing of optically-selected galaxies.Comment: Accepted for publication in The Astrophysical Journal Letters, Sept. 23, 1994. 10 pages uuencoded compressed postscript, including two figures. JHU-9410200

What are the Best Hierarchical Descriptors for Complex Networks?

This work reviews several hierarchical measurements of the topology of complex networks and then applies feature selection concepts and methods in order to quantify the relative importance of each measurement with respect to the discrimination between four representative theoretical network models, namely Erd\"{o}s-R\'enyi, Barab\'asi-Albert, Watts-Strogatz as well as a geographical type of network. The obtained results confirmed that the four models can be well-separated by using a combination of measurements. In addition, the relative contribution of each considered feature for the overall discrimination of the models was quantified in terms of the respective weights in the canonical projection into two dimensions, with the traditional clustering coefficient, hierarchical clustering coefficient and neighborhood clustering coefficient resulting particularly effective. Interestingly, the average shortest path length and hierarchical node degrees contributed little for the separation of the four network models.Comment: 9 pages, 4 figure

An Analytical Approach to Neuronal Connectivity

This paper describes how realistic neuromorphic networks can have their connectivity properties fully characterized in analytical fashion. By assuming that all neurons have the same shape and are regularly distributed along the two-dimensional orthogonal lattice with parameter $\Delta$, it is possible to obtain the accurate number of connections and cycles of any length from the autoconvolution function as well as from the respective spectral density derived from the adjacency matrix. It is shown that neuronal shape plays an important role in defining the spatial spread of network connections. In addition, most such networks are characterized by the interesting phenomenon where the connections are progressively shifted along the spatial domain where the network is embedded. It is also shown that the number of cycles follows a power law with their respective length. Morphological measurements for characterization of the spatial distribution of connections, including the adjacency matrix spectral density and the lacunarity of the connections, are suggested. The potential of the proposed approach is illustrated with respect to digital images of real neuronal cells.Comment: 4 pages, 6 figure

Tecnologias para redução do uso do fogo na agricultura.

A Embrapa tem realizado pesquisas e transferência de tecnologias visando à diminuição ou total eliminação do uso do fogo. O objetivo é desenvolver e validar sistemas de produção, gerar informações e resultados científicos sobre plantios que permitam o uso do solo por mais tempo, como a Integração Lavoura-Pecuária-Floresta, sistemas agroflorestais comerciais e sistemas florestais.bitstream/item/136066/1/PortalDiadeCampoLiane.pd