5,779 research outputs found
Degree-dependent intervertex separation in complex networks
We study the mean length of the shortest paths between a vertex of
degree and other vertices in growing networks, where correlations are
essential. In a number of deterministic scale-free networks we observe a
power-law correction to a logarithmic dependence, in a wide range of network
sizes. Here is the number of vertices in the network, is the
degree distribution exponent, and the coefficients and depend on a
network. We compare this law with a corresponding dependence obtained
for random scale-free networks growing through the preferential attachment
mechanism. In stochastic and deterministic growing trees with an exponential
degree distribution, we observe a linear dependence on degree, . We compare our findings for growing networks with those for
uncorrelated graphs.Comment: 8 pages, 3 figure
The Mass Function of Field Galaxies at 0.4 < z < 1.2 Derived From the MUNICS K-Selected Sample
We derive the number density evolution of massive field galaxies in the
redshift range 0.4 < z < 1.2 using the K-band selected field galaxy sample from
the Munich Near-IR Cluster Survey (MUNICS). We rely on spectroscopically
calibrated photometric redshifts to determine distances and absolute magnitudes
in the rest-frame K-band. To assign mass-to-light ratios, we use two different
approaches. First, we use an approach which maximizes the stellar mass for any
K-band luminosity at any redshift. We take the mass-to-light ratio of a Simple
Stellar Population (SSP) which is as old as the universe at the galaxy's
redshift as a likely upper limit. Second, we assign each galaxy a mass-to-light
ratio by fitting the galaxy's colours against a grid of composite stellar
population models and taking their M/L. We compute the number density of
galaxies more massive than 2 x 10^10 h^-2 Msun, 5 x 10^10 h^-2 Msun, and 1 x
10^11 h^-2 Msun, finding that the integrated stellar mass function is roughly
constant for the lowest mass limit and that it decreases with redshift by a
factor of ~ 3 and by a factor of ~ 6 for the two higher mass limits,
respectively. This finding is in qualitative agreement with models of
hierarchical galaxy formation, which predict that the number density of ~ M*
objects is fairly constant while it decreases faster for more massive systems
over the redshift range our data probe.Comment: 6 pages, 2 figures, to appear in the proceedings of the ESO/USM
Workshop "The Mass of Galaxies at Low and High Redshift", Venice (Italy),
October 24-26, 200
The Munich Near-Infrared Cluster Survey (MUNICS) - Number density evolution of massive field galaxies to z ~ 1.2 as derived from the K-band selected survey
We derive the number density evolution of massive field galaxies in the
redshift range 0.4 < z < 1.2 using the K-band selected field galaxy sample from
the Munich Near-IR Cluster Survey (MUNICS). We rely on spectroscopically
calibrated photometric redshifts to determine distances and absolute magnitudes
in the rest-frame K-band. To assign mass-to-light ratios, we use an approach
which maximizes the stellar mass for any K-band luminosity at any redshift. We
take the mass-to-light ratio, M/L_K, of a Simple Stellar Population (SSP) which
is as old as the universe at the galaxy's redshift as a likely upper limit.
This is the most extreme case of pure luminosity evolution and in a more
realistic model M/L_K will probably decrease faster with redshift due to
increased star formation. We compute the number density of galaxies more
massive than 2 10^10 h^-2 solar masses, 5 10^10 h^-2 solar masses, and 1 10^11
h^-2 solar masses, finding that the integrated stellar mass function is roughly
constant for the lowest mass limit and that it decreases with redshift by a
factor of roughly 3 and by a factor of roughly 6 for the two higher mass
limits, respectively. This finding is in qualitative agreement with models of
hierarchical galaxy formation, which predict that the number density of ~ M*
objects is fairly constant while it decreases faster for more massive systems
over the redshift range our data probe.Comment: 4 pages, 5 figures, accepted for publication in ApJ Letter
Avaliação de frutos de tucumanzeiros selecionados para alto teor de óleo na polpa.
O tucumanzeiro Astrocaryum vulgare Mart. é uma palmeira arbórea da família Arecaceae, nativa da Amazônia, que possui caule em touceira e frutos com alto potencial econômico. Por ser uma espécie de múltipla utilidade, na última década passou a ser indicada como matéria prima para a produção de biodiesel. Análises quantitativas e qualitativas do óleo extraído da polpa dos frutos foram realizadas elevaram a seleção de matrizes com alto teor de óleo. Contudo informações sobre aspectos físicos de seus frutos ainda são inexistentes. Assim, este trabalho objetivou avaliar frutos de matrizes de tucumanzeiro selecionadas para alto teor de óleo na polpa. Foram coletadas 3 amostras de 5 frutos retirados de 3 cachos consecutivos de 29 matrizes selecionadas no BAG- tucumã da Amazônia Oriental. Os dados obtidos foram analisados por meio de estatística descritiva. Foi constatada variação para todos os caracteres analisados. Os frutos apresentaram em média 41,8 mm e 34,3 mm de diâmetro longitudinal e transversal, respectivamente. O peso médio dos frutos foi de 31,8g sendo que 19,9g constituiu a polpa, representando 62,58% de parte comestível. As espessuras da polpa, do endocarpo e da amêndoa foram 4,8 mm, 3,2 mm e 7,1 mm, respectivamente. Todas as matrizes apresentaram altos rendimentos de polpa por fruto variando de 54,8% a 69,7%. Portanto pode-se considerar que as matrizes selecionadas apresentam ampla variação e alto rendimento de polpa por fruto.VII ENAAG
Large-Scale Structure in the NIR-Selected MUNICS Survey
The Munich Near-IR Cluster Survey (MUNICS) is a wide-area, medium-deep,
photometric survey selected in the K' band. The project's main scientific aims
are the identification of galaxy clusters up to redshifts of unity and the
selection of a large sample of field early-type galaxies up to z < 1.5 for
evolutionary studies. We created a Large Scale Structure catalog, using a new
structure finding technique specialized for photometric datasets, that we
developed on the basis of a friends-of-friends algorithm. We tested the
plausibility of the resulting galaxy group and cluster catalog with the help of
Color-Magnitude Diagrams (CMD), as well as a likelihood- and Voronoi-approach.Comment: 4 pages, to appear in "The Evolution of Galaxies III. From Simple
Approaches to Self-Consistent Models", proceedings of the 3rd EuroConference
on the evolution of galaxies, held in Kiel, Germany, July 16-20, 200
C2. Pneumonia adquirida na comunidade (PAC) – influência da terapêutica com macrólidos ou novas fluoroquinolonas na evolução e duração de internamento
The need to cover atypical agents in the initial Community-Acquired Pneumonia (CAP) inpatients therapy is currently the focus of much debate. A lack of consensus in this issue might relate to regional variation in the prevalence of atypical agents. The most recent American guidelines (ATS and IDSA) suggest the use of a macrolid or a antipneumococcal fluoroquinolone in the initial empirical therapy of CAP, so that atypical agents are also always covered. This study aimed to compare the progression and length of hospitalization between CAP patients treated with a combination of a beta-lactamic antibiotic and a macrolid or a new quinolone (Group I) and other form of therapy without atypical agent coverage (Group II). A retrospective study was performed with 180 inpatients, admitted with PAC diagnosis between December 2000 and May 2002 in a general Pneumology Service. 105 (58,3%) patients were included in Group I and 75 (41,7%) in Group II. There were no statistically significant differences between the two groups regarding age, sex, clinical presentation, co morbidities or severity of the inaugural presentation. There were 14 patients with unfavourable clinical progression belonging 50% of them to Group I. The average of the length of hospital stay in Group I was 12.2 days and 13.7 days in Group II, which is also a non-significant statistical difference.Then, we may conclude that initial therapy covering atypical agents might not always be necessary. Prospective studies will be important to further address this question and to investigate the epidemiology of atypical agents of CAP in Portugal
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