Master Operators Govern Multifractality in Percolation

Using renormalization group methods we study multifractality in percolation at the instance of noisy random resistor networks. We introduce the concept of master operators. The multifractal moments of the current distribution (which are proportional to the noise cumulants $C_R^{(l)} (x, x^\prime)$ of the resistance between two sites x and $x^\prime$ located on the same cluster) are related to such master operators. The scaling behavior of the multifractal moments is governed exclusively by the master operators, even though a myriad of servant operators is involved in the renormalization procedure. We calculate the family of multifractal exponents ${\psi_l}$ for the scaling behavior of the noise cumulants, $C_R^{(l)} (x, x^\prime) \sim | x - x^\prime |^{\psi_l /\nu}$, where $\nu$ is the correlation length exponent for percolation, to two-loop order.Comment: 6 page

Diferenciação de cultivares de feijão de origem transgênica e convencional por RMN HR-MAS de 1H e análise quimiométrica.

O objetivo do presente estudo foi avaliar as diferenças na composição química dos grãos dos cultivares Olathe Pinto convencional e o seu geneticamente modificado (Olathe Pinto 5.1) e uma possível transferência gênica aos cultivares Pontal e Perola, utilizando a ressonância magnética nuclear, em análise particular da técnica HR-MAS, e técnicas quimiométricas.Conpeex 2010

Comparação entre extratores químicos de fósforo disponível.

Foram comparados três extratos quimicos de fósforo dispon¡vel em um Latossolo Vermelho-Escuro submetido a quatro tratamentos de adubação fosfatada (0, 150 e 450 mg de P/dm3 de solo). Os extratores qu¡micos testados foram: Mehlich 1, Mehlich 3 e resina trocadora de ânions. Entre esses, sobressaiu-se a resina, com maiores coeficientes de correlação entre a matéria seca da parte aérea de plantas de milho e o fósforo acumulado no tecido vegetal e com o fósforo extra¡do do solo. A resina também recuperou maior quantidade de fósforo do solo, além de ter apresentado correlação significativa com os outros extratores.bitstream/item/35785/1/Bol18.pd

Logarithmic Corrections in Dynamic Isotropic Percolation

Based on the field theoretic formulation of the general epidemic process we study logarithmic corrections to scaling in dynamic isotropic percolation at the upper critical dimension d=6. Employing renormalization group methods we determine these corrections for some of the most interesting time dependent observables in dynamic percolation at the critical point up to and including the next to leading correction. For clusters emanating from a local seed at the origin we calculate the number of active sites, the survival probability as well as the radius of gyration.Comment: 9 pages, 3 figures, version to appear in Phys. Rev.

Percolation Threshold, Fisher Exponent, and Shortest Path Exponent for 4 and 5 Dimensions

We develop a method of constructing percolation clusters that allows us to build very large clusters using very little computer memory by limiting the maximum number of sites for which we maintain state information to a number of the order of the number of sites in the largest chemical shell of the cluster being created. The memory required to grow a cluster of mass s is of the order of $s^\theta$ bytes where $\theta$ ranges from 0.4 for 2-dimensional lattices to 0.5 for 6- (or higher)-dimensional lattices. We use this method to estimate $d_{\scriptsize min}$, the exponent relating the minimum path $\ell$ to the Euclidean distance r, for 4D and 5D hypercubic lattices. Analyzing both site and bond percolation, we find $d_{\scriptsize min}=1.607\pm 0.005$ (4D) and $d_{\scriptsize min}=1.812\pm 0.006$ (5D). In order to determine $d_{\scriptsize min}$ to high precision, and without bias, it was necessary to first find precise values for the percolation threshold, $p_c$: $p_c=0.196889\pm 0.000003$ (4D) and $p_c=0.14081\pm 0.00001$ (5D) for site and $p_c=0.160130\pm 0.000003$ (4D) and $p_c=0.118174\pm 0.000004$ (5D) for bond percolation. We also calculate the Fisher exponent, $\tau$, determined in the course of calculating the values of $p_c$: $\tau=2.313\pm 0.003$ (4D) and $\tau=2.412\pm 0.004$ (5D)

Mecanismos bioquímicos, fisiológicos e moleculares relacionados com a eficiência de uso de nitrogênio em leguminosas e gramíneas.

Absorção do nitrogênio pelas plantas; Assimilação do nitrogênio pelas plantas; Ação das enzimas na eficiência de uso do nitrogênio; Identificação de genes relacionados à eficiência de uso do nitrogênio; Genes envolvidos na absorção do nitrato; Genes envolvidos na absorção do amônio; Estudos genéticos da eficiência de uso do nitrogênio; Variação da eficiência de uso de nitrogênio em gramíneas e leguminosas.bitstream/CPAMN-2010/24172/1/doc195.pd

Characterization of cover crops by NMR spectroscopy: impacts on soil carbon, nitrogen and phosphorus under tilage regimes.

The objective of this study was to investigate the chemical composition of cover crops by solid-state CPMAS 13C NMR spectroscopy and its effects on carbon, nitrogen and phosphorus in a Typic Acrustox. Cover crops (Crotalaria juncea, Canavalia brasiliensis, Cajanus cajan, Mucuna pruriens and Raphanus sativus) and natural fallow were studied in rotation with maize under conventional and no-tillage regimes. Tissues of Crotalaria juncea, Canavalia brasiliensis, Mucuna pruriens and Raphanus sativus were analyzed using CPMAS 13C NMR spectroscopy. Soil samples were collected at the end of the growing season of the cover crops (September 2002) and during the grain filling period in corn from 0-5 and 5-10 cm layers. Cajanus cajan presented the lowest content of polysaccharides and along with Mucuna pruriens presented the highest percentage of aromatic carbon compounds, reflecting the slow decomposition of highly lignified material. Carbon stocks were higher in the superficial soil layer and under no-tillage due to the accumulation and slower decomposition of plant tissues under these conditions. Increases in the C/N ratio of the soil with Mucuna pruriens and the C/P ratio with Cajanus cajan in the dry season were also related to slower rates of decomposition, caused by the large concentration of aromatic compounds in the tissues of these species. The higher C/P ratios found at 0-5 cm layer are due to higher values of P (Mehlich-1) at 5-10 cm (25 mg kg-1) layer and the higher concentration of carbon in the superficial soil layer as a result of the accumulation of plant residues

Relações entre a contribuição da fixação biológica de nitrogênio e a duração do ciclo de diferentes genótipos de cultivos de leguminosas de grãos.

Contribuição da FBN por culturas de diferentes ciclos; A senescência dos nódulos como fator limitante da FBN em genótipos de ciclo curto; Mecanismos da senescência precoce dos nódulos.bitstream/CPAMN-2010/24174/1/doc197.pd

Demandas do agronegócio maranhense.

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