Crossovers from parity conserving to directed percolation universality

The crossover behavior of various models exhibiting phase transition to absorbing phase with parity conserving class has been investigated by numerical simulations and cluster mean-field method. In case of models exhibiting Z_2 symmetric absorbing phases (the NEKIMCA and Grassberger's A stochastic cellular automaton) the introduction of an external symmetry breaking field causes a crossover to kink parity conserving models characterized by dynamical scaling of the directed percolation (DP) and the crossover exponent: 1/\phi ~ 0.53(2). In case an even offspringed branching and annihilating random walk model (dual to NEKIMCA) the introduction of spontaneous particle decay destroys the parity conservation and results in a crossover to the DP class characterized by the crossover exponent: 1/\phi\simeq 0.205(5). The two different kinds of crossover operators can't be mapped onto each other and the resulting models show a diversity within the DP universality class in one dimension. These 'sub-classes' differ in cluster scaling exponents.Comment: 6 pages, 6 figures, accepted version in PR

A supercritical series analysis for the generalized contact process with diffusion

We study a model that generalizes the CP with diffusion. An additional transition is included in the model so that at a particular point of its phase diagram a crossover from the directed percolation to the compact directed percolation class will happen. We are particularly interested in the effect of diffusion on the properties of the crossover between the universality classes. To address this point, we develop a supercritical series expansion for the ultimate survival probability and analyse this series using d-log Pad\'e and partial differential approximants. We also obtain approximate solutions in the one- and two-site dynamical mean-field approximations. We find evidences that, at variance to what happens in mean-field approximations, the crossover exponent remains close to $\phi=2$ even for quite high diffusion rates, and therefore the critical line in the neighborhood of the multicritical point apparently does not reproduce the mean-field result (which leads to $\phi=0$) as the diffusion rate grows without bound

Efeito da temperatura sobre a germinação de sementes de cebola.

As atividades antrópicas, aliadas aos fatores naturais estão causando alterações no clima, como o aumento da temperatura média no planeta. Entre os diversos fatores que podem afetar a germinação de hortaliças, a temperatura é considerada um dos mais importantes. Assim, o objetivo deste trabalho foi avaliar a germinação de três cultivares de cebola (Allium cepa L.) submetidas a diferentes temperaturas. Sementes de cebola das cultivares: Franciscana IPA-10, Valeouro IPA-11 e Alfa São Francisco foram mantidas em incubadoras tipo BOD, sob cinco temperaturas constantes (15, 20, 25, 30 e 35 ºC ) e fotoperíodo de doze horas de luz. As variáveis avaliadas foram: germinação (G), velocidade de germinação (VG) índice de velocidade de germinação (IVG), e tempo médio de germinação (TMG). O delineamento experimental utilizado foi inteiramente casualizado, com três cultivares e cinco temperaturas em arranjo fatorial 3x5 com quatro repetições de 25 sementes de cada cultivar. As temperaturas afetaram a G, VG, IVG e TMG para as três cultivares. A temperatura ótima para a germinação da cebola variou de 15 a 22 ºC de acordo com a cultivar. Temperaturas acima de 30 oC foram desfavoráveis para a germinação das cultivares de cebola testadas

Soil Phosphorus Availability and Eucalypt Phosphorus Uptake from Soluble and Insoluble Sources of Phosphorus

P recovery efficiency from natural rock phosphates and a concentrated phosphate by Eucalyptus grandis plantation in relation to triple superphosphate was evaluated in field trials conducted in the cerrado area of Brazil. Two experiments were carried out in two sites of the Savanna area of Minas Gerais State, Brazil. The rates of the natural phosphates (RP)  Araxa and Patos de Minas(P2O5 24% and Ca 25%),  were 500, 1000, 2000, and 4000 kg/ha and Arafertil (33% -P2O5 and 33% Ca)concentrated rock was tested using 1000kg/ha rate only. The triple superphosphate (TP = 45% -P2O5 and 13% Ca) was applied at 250, 500, 1000, and 2000 kg/ha. Mehlich -1 and Bray -1 extractants were used to extract P from the soil. The concentration of P extracted varied with the reagent used.  Mehlich-1 extracted about 38.8% more P over the Bray -1 extractant at both sites, although, in one of the sites the extraction was 18% higher than the other. On both experimental sites, application of phosphate from both natural and concentrated forms increased tree height, stem volume and above ground dry matter production, but there was no difference between them at the rate of 1000 kg/ha. P-fixing capacity by trees increased with increasing soil P utilization efficiency. P recovery by the trees varied from 3 to 11% depending on rates and source. But P fixing capacity was higher for TP than for RP. Keywords: Araxa rock, concentrated arafertil; recovery efficiency, P-fixing capacity and eucalypt

Evidence of Substructure in the Cluster of Galaxies A3558

We investigate the dynamical properties of the cluster of galaxies A3558 (Shapley 8). Studying a region of one square degree ($\sim$ 3 Mpc$^2$) centered on the cluster cD galaxy, we have obtained a statistically complete photometric catalog with positions and magnitudes of 1421 galaxies (down to a limiting magnitude of $B \sim 21$). This catalog has been matched to the recent velocity data obtained by Mazure et al. (1997) and from the literature, yielding a radial velocity catalog containing 322 galaxies. Our analysis shows that the position/velocity space distribution of galaxies shows significant substructure. A central bimodal core detected previously in preliminary studies is confirmed by using the Adaptive Kernel Technique and Wavelet Analysis. We show that this central bimodal subtructure is nevertheless composed of a projected feature, kinematically unrelated to the cluster, plus a group of galaxies probably in its initial merging phase into a relaxed core. The cD velocity offset with respect to the average cluster redshift, reported earlier by several authors, is completely eliminated as a result of our dynamical analysis. The untangling of the relaxed core component also allows a better, more reliable determination of the central velocity dispersion, which in turn eliminates the ``$\beta$-problem'' for A3558. The cluster also shows a ``preferential'' distribution of subclumps coinciding with the direction of the major axis position angle of the cD galaxy and of the central X-ray emission ellipsoidal distribution, in agreement with an anisotropic merger scenario.Comment: 35 pages in latex, 17 figures in Postscript, accepted for publication in the Astrophysical Journa

Avaliação de cultivares de gergelim no Seridó Paraibano - 2000.

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Germinação de sementes de pimenta-rosa (Schinus terebinthifolius raddi) submetidas a diferentes temperaturas.

O presente trabalho tem como objetivo, avaliar o comportamento germinativo de sementes de pimenta-rosa quando submetidas a diferentes temperaturas. As sementes utilizadas foram coletadas no mês de setembro de 2009 de uma população existente próximo à Universidade de Brasília, Brasilia-DF. A semeadura foi feita separadamente em caixas tipo gerbox sob papel mata-borrão umedecido com 15mL de água, posteriormente as caixas foram incubadas em uma BOD sob diferentes temperaturas (20, 25, 30, 25/30°C) durante 15 dias onde foi avaliado diariamente a porcentagem de germinação, ao final do experimento foram calculados, o tempo médio de germinação, velocidade de germinação, indice de velocidade de germinação (IVG)

Evaluation of thermal and non-thermal processing effect on non-prebiotic and prebiotic acerola juices using 1HqNMR and GC - MS coupled to chemometrics.

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