22,234 research outputs found
Properties of Very Luminous Galaxies
Recent analysis of the SSRS2 data based on cell-counts and two-point
correlation function has shown that very luminous galaxies are much more
strongly clustered than fainter galaxies. In fact, the amplitude of the
correlation function of very luminous galaxies () asymptotically
approaches that of clusters. In this paper we investigate the
properties of the most luminous galaxies, with blue absolute magnitude . We find that: 1) the population mix is comparable to that in other ranges
of absolute magnitudes; 2) only a small fraction are located in bona fide
clusters; 3) the bright galaxy-cluster cross-correlation function is
significantly higher on large scales than that measured for fainter galaxies;
4) the correlation length of galaxies brighter than \MB ,
expressed as a function of the mean interparticle distance, appears to follow
the universal dimensionless correlation function found for clusters and radio
galaxies; 5) a large fraction of the bright galaxies are in interacting pairs,
others show evidence for tidal distortions, while some appear to be surrounded
by faint satellite galaxies. We conclude that very luminous optical galaxies
differ from the normal population of galaxies both in the clustering and other
respects. We speculate that this population is highly biased tracers of mass,
being associated to dark halos with masses more comparable to clusters than
typical loose groups.Comment: 29 pages (6 figures) + 2 tables; paper with all figures and images
available at http://boas5.bo.astro.it/~cappi/papers.html; The Astronomical
Journal, in pres
2D pattern evolution constrained by complex network dynamics
Complex networks have established themselves along the last years as being
particularly suitable and flexible for representing and modeling several
complex natural and human-made systems. At the same time in which the
structural intricacies of such networks are being revealed and understood,
efforts have also been directed at investigating how such connectivity
properties define and constrain the dynamics of systems unfolding on such
structures. However, lesser attention has been focused on hybrid systems,
\textit{i.e.} involving more than one type of network and/or dynamics. Because
several real systems present such an organization (\textit{e.g.} the dynamics
of a disease coexisting with the dynamics of the immune system), it becomes
important to address such hybrid systems. The current paper investigates a
specific system involving a diffusive (linear and non-linear) dynamics taking
place in a regular network while interacting with a complex network of
defensive agents following Erd\"os-R\'enyi and Barab\'asi-Albert graph models,
whose nodes can be displaced spatially. More specifically, the complex network
is expected to control, and if possible to extinguish, the diffusion of some
given unwanted process (\textit{e.g.} fire, oil spilling, pest dissemination,
and virus or bacteria reproduction during an infection). Two types of pattern
evolution are considered: Fick and Gray-Scott. The nodes of the defensive
network then interact with the diffusing patterns and communicate between
themselves in order to control the spreading. The main findings include the
identification of higher efficiency for the Barab\'asi-Albert control networks.Comment: 18 pages, 32 figures. A working manuscript, comments are welcome
Desempenho produtivo de caprinos mestiços da raça Anglo-Nubiana, no Acre.
O experimento foi conduzido na Fazenda Experimental do Centro de Pesquisa Agroflorestal do Acre - CPAF-Acre, localizada no municÃpio de Rio Branco. Foram utilizados inicialmente 20 matrizes e dois reprodutores mestiços da raça An-glo-nubiana, criados em regime semi-intensivo de exploração, tendo como base alimentar pastagens de colonião (Panicum maximum) e brizantão (Brachiaria brizan-tha). O sistema de acasalamento adotado foi o da monta natural a campo, onde o macho permanecia com as fêmeas durante todo o ano. Foram obtidos os Ãndices de prolificidade (1,26%) natalidade (125,2 %); fertilidade ao parto (87,5%); intervalo entre partos (266,2 dias); proporção sexual (50%); mortalidade de 0-6 meses (14,63%); peso ao nascer para machos (2,81 i<g), para fêmeas (2,71 kg) e fêmeas com três partos em dois anos (7,9%). Ocorreram parições em quase todos os meses do ano (exceto setembro), com uma maior concentração no perÃodo de junho a agosto (413%). As cabras que tiveram parto duplo apresentaram um peso ao parto maior (P< 0,01), em relação à quelas com panos simples. Conclui-se que o desempenho reprodutivo do rebanho estudado foi bom, podendo, no entanto, atingir Ãndices mais elevados, desde que se introduzam, no sistema de criação, algumas práticas de manejo reprodutivo e melhores condições nutriclonais.bitstream/item/161362/1/975.pd
Comportamento produtivo e reprodutivo de bubalinos mestiços Murrah-Mediterrâneo em pastagem cultivada de terra firme, no Estado do Acre.
Foi estudado o desempenho produtivo e reprodutivo de bubalinos mestiços Murrah-Mediterrâneo nas condições de terra firme de Rio Branco, Acre, no perÃodo de 1985 a 1993. Os estudos foram realizados na Estação Experimental do Centro de Pesquisa Agroflorestal do Acre (CPAF-Acre), da EMBRAPA. A base alimentar dos animais experimentais constituiu-se de pastagens de quicuio-da-amazônia (Brachiaria humidicola) , Andropogon gayanus e Brachiaria brizantha cv. Marandu. Os resultados mostraram que os bubalinos apresentaram um ganho de peso diário de 610g até os 24 meses de idade, com um peso vivo de 441kg. A média anual de produção de leite foi de 5,4kg/animal/dia, bem superior à média do rebanho bovino leiteiro do Acre (2,5kglvaca/dia). Estes dados evidenciam que a criação de búfalos para a produção de carne e leite, nas condições de terra firme, é uma alternativa viável para a diversificação da atividade pecuária e uma opção para o melhor aproveitamento das estruturas das fazendas produtoras de bovinos do Acre.bitstream/item/161589/1/970.pd
Labels for non-individuals
Quasi-set theory is a first order theory without identity, which allows us to
cope with non-individuals in a sense. A weaker equivalence relation called
``indistinguishability'' is an extension of identity in the sense that if
is identical to then and are indistinguishable, although the
reciprocal is not always valid. The interesting point is that quasi-set theory
provides us a useful mathematical background for dealing with collections of
indistinguishable elementary quantum particles. In the present paper, however,
we show that even in quasi-set theory it is possible to label objects that are
considered as non-individuals. We intend to prove that individuality has
nothing to do with any labelling process at all, as suggested by some authors.
We discuss the physical interpretation of our results.Comment: 11 pages, no figure
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
Surviving opinions in Sznajd models on complex networks
The Sznajd model has been largely applied to simulate many sociophysical
phenomena. In this paper we applied the Sznajd model with more than two
opinions on three different network topologies and observed the evolution of
surviving opinions after many interactions among the nodes. As result, we
obtained a scaling law which depends of the network size and the number of
possible opinions. We also observed that this scaling law is not the same for
all network topologies, being quite similar between scale-free networks and
Sznajd networks but different for random networks.Comment: 9 pages, 3 figure
Beyond the average: Detecting global singular nodes from local features in complex networks
Deviations from the average can provide valuable insights about the
organization of natural systems. The present article extends this important
principle to the systematic identification and analysis of singular motifs in
complex networks. Six measurements quantifying different and complementary
features of the connectivity around each node of a network were calculated, and
multivariate statistical methods applied to identify singular nodes. The
potential of the presented concepts and methodology was illustrated with
respect to different types of complex real-world networks, namely the US air
transportation network, the protein-protein interactions of the yeast
Saccharomyces cerevisiae and the Roget thesaurus networks. The obtained
singular motifs possessed unique functional roles in the networks. Three
classic theoretical network models were also investigated, with the
Barab\'asi-Albert model resulting in singular motifs corresponding to hubs,
confirming the potential of the approach. Interestingly, the number of
different types of singular node motifs as well as the number of their
instances were found to be considerably higher in the real-world networks than
in any of the benchmark networks
O uso de ducha: efeito sobre a classificação de qualidade da carne em suÃnos transportados para o abate.
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