Anisotropy and percolation threshold in a multifractal support

Recently a multifractal object, $Q_{mf}$, was proposed to study percolation properties in a multifractal support. The area and the number of neighbors of the blocks of $Q_{mf}$ show a non-trivial behavior. The value of the probability of occupation at the percolation threshold, $p_{c}$, is a function of $\rho$, a parameter of $Q_{mf}$ which is related to its anisotropy. We investigate the relation between $p_{c}$ and the average number of neighbors of the blocks as well as the anisotropy of $Q_{mf}$

Teor de açúcar da água residuária do processamento do café.

A fermentação dos açúcares contidos na mucilagem da água residuária do café (ARC) possibilita obter álcool. Para se obter bom rendimento de álcool é necessário ajustar o teor de açúcar da ARC para 16° Brix. O trabalho teve como objetivo quantificar os teores de açúcar da ARC, após sucessivas reciclagens no processo de desmucilamento. Colocou-se água de torneira em amostras de café cereja descascado, das variedades Bourbon Vermelho e Bourbon Amarelo, e a mucilagem foi extraída, girando-se um bastão de vidro, por 3 minutos. Foram feitas até seis extrações, em seqüência, reciclando-se a ARC obtida. Os teores de açúcar da ARC aumentaram linearmente com o aumento do número de extrações realizadas. O teor de açúcar da ARC elevou-se de 3,1 para 9,3° Brix, após cinco extrações, e de 2,6 para 10,3° Brix, após seis extrações da mucilagem do cereja descascado, das variedades Bourbon Vermelho e Bourbon Amarelo, respectivamente

The Mass-to-Light Ratio of Binary Galaxies

We report on the mass-to-light ratio determination based on a newly selected binary galaxy sample, which includes a large number of pairs whose separations exceed a few hundred kpc. The probability distributions of the projected separation and the velocity difference have been calculated considering the contamination of optical pairs, and the mass-to-light ratio has been determined based on the maximum likelihood method. The best estimate of $M/L$ in the B band for 57 pairs is found to be 28 $\sim$ 36 depending on the orbital parameters and the distribution of optical pairs (solar unit, $H_0=50$ km s$^{-1}$ Mpc$^{-1}$). The best estimate of $M/L$ for 30 pure spiral pairs is found to be 12 $\sim$ 16. These results are relatively smaller than those obtained in previous studies, but consistent with each other within the errors. Although the number of pairs with large separation is significantly increased compared to previous samples, $M/L$ does not show any tendency of increase, but found to be almost independent of the separation of pairs beyond 100 kpc. The constancy of $M/L$ beyond 100 kpc may indicate that the typical halo size of spiral galaxies is less than $\sim 100$ kpc.Comment: 18 pages + 8 figures, to appear in ApJ Vol. 516 (May 10

Group theory for structural analysis and lattice vibrations in phosphorene systems

Group theory analysis for two-dimensional elemental systems related to phosphorene is presented, including (i) graphene, silicene, germanene and stanene, (ii) dependence on the number of layers and (iii) two stacking arrangements. Departing from the most symmetric $D_{6h}^{1}$ graphene space group, the structures are found to have a group-subgroup relation, and analysis of the irreducible representations of their lattice vibrations makes it possible to distinguish between the different allotropes. The analysis can be used to study the effect of strain, to understand structural phase transitions, to characterize the number of layers, crystallographic orientation and nonlinear phenomena.Comment: 24 pages, 3 figure

NIR Luminosity Function of Galaxies in Close Major-Merger Pairs and Mass Dependence of Merger Rate

A sample of close major-merger pairs (projected separation ${\rm 5 \leq r \leq 20 h^{-1}}$ kpc, ${\rm K_s}$ band magnitude difference $\delta {\rm K_s} \leq 1$ mag) is selected from the matched 2MASS-2dFGRS catalog of Cole et al. (2001). The pair primaries are brighter than ${\rm K_s} = 12.5$ mag. After corrections for various biases, the comparison between counts in the paired galaxy sample and counts in the parent sample shows that for the local `M* galaxies' sampled by flux limited surveys, the fraction of galaxies in the close major-merger pairs is 1.70$\pm 0.32$. Using 38 paired galaxies in the sample, a ${\rm K_s}$ band luminosity function (LF) is calculated. This is the first unbiased LF for a sample of objectively defined interacting/merging galaxies in the local universe, while all previously determined LFs of paired galaxies are biased by mistreating paired galaxies as singles. A stellar mass function (MF) is translated from the LF. Compared to the LF/MF of 2MASS galaxies, a differential pair fraction function is derived. The results suggest a trend in the sense that less massive galaxies may have lower chance to be involved in close major-merger pairs than more massive galaxies. The algorithm presented in this paper can be easily applied to much larger samples of 2MASS galaxies with redshifts in near future.Comment: Accepted by ApJL, 16 pages, 2 figure

Avaliação de tolerância à seca em progênies híbridas de citros.

O Brasil destaca-se como maior produtor mundial de citros e maior produtor e exportador de suco concentrado congelado de laranja, sendo a Bahia o segundo maior produtor de laranja do país, superada apenas por São Paulo. Apesar da sua importância, a vulnerabilidade da citricultura nordestina, a exemplo da brasileira, é grande, pela presença quase única da combinação laranjeira 'Pera' [Citrus sinensis (L.) Osbeck] / limoeiro 'Cravo' (C. limonia Osbeck) na sustentação dos pomares, tornando urgente um programa de diversificação de variedades. A citricultura baiana está concentrada na Grande Unidade de Paisagem de Tabuleiros Costeiros, onde são registradas precipitações pluviais anuais de 1.000 mm a 1.200 mm, distribuídas em 8 a 10 meses, com dois a seis meses de deficiência hídrica, sendo o uso de irrigação praticamente nulo. Assim, é desejável o emprego de combinações copa / porta-enxerto que, entre outras características de interesse agronômico, sejam tolerantes à seca. Este trabalho teve como objetivo a identificação, dentro de progênies obtidas a partir de cruzamentos controlados, de seedlings (pés-francos) híbridos com potencial para tolerância à seca.PDF. 061

Avaliação dos impactos ambientais e socioeconômicos do sistema de produção de leite a pasto na Fazenda Escola de Cachoeiras de Macacu.

Resumo: A Fazenda Escola de Cachoeiras de Macacu da Universidade Federal Fluminense está implantando um sistema de produção de leite a pasto. Entretanto, qualquer sistema de produção animal é capaz de trazer impactos ambientais importantes. Assim, o objetivo deste trabalho foi avaliar os impactos ambientais e socioeconômicos da implantação dessa tecnologia, utilizando-se o Sistema Ambitec-Agro, desenvolvido pela Embrapa Meio Ambiente. O índice geral de impacto da atividade foi de 0,99 (em escala ±15), observando-se impactos socioeconômicos positivos, mas potencial para ocorrência de impactos ambientais negativos. Sugere-se a adoção de técnicas alternativas de manejo para a mitigação desses impactos

Multilocus sequence types of invasive Corynebacterium diphtheriae isolated in the Rio de Janeiro urban area, Brazil

Invasive infections caused by Corynebacterium diphtheriae in vaccinated and non-vaccinated individuals have been reported increasingly. In this study we used multilocus sequence typing (MLST) to study genetic relationships between six invasive strains of this bacterium isolated solely in the urban area of Rio de Janeiro, Brazil, during a 10-year period. Of note, all the strains rendered negative results in PCR reactions for the tox gene, and four strains presented an atypical sucrose-fermenting ability. Five strains represented new sequence types. MLST results did not support the hypothesis that invasive (sucrose-positive) strains of C. diphtheriae are part of a single clonal complex. Instead, one of the main findings of the study was that such strains can be normally found in clonal complexes with strains related to non-invasive disease. Comparative analyses with C. diphtheriae isolated in different countries provided further information on the geographical circulation of some sequence types