Sistemas silvipastoris na Amazônia Oriental.

A problemática das pastagens. Os sistemas silvipastoris (SSP). O papel da árvore. Interação árvore - pastagem. Componente animal. Sistemas silvipastoris praticados na Amazônia Oriental. Avaliação de sistemas silvipastoris. Adoção de sistemas silvipastoris.bitstream/item/63268/1/Oriental-Doc56.pd

Vanishing Viscous Limits for 3D Navier-Stokes Equations with A Navier-Slip Boundary Condition

In this paper, we investigate the vanishing viscosity limit for solutions to the Navier-Stokes equations with a Navier slip boundary condition on general compact and smooth domains in $\mathbf{R}^3$. We first obtain the higher order regularity estimates for the solutions to Prandtl's equation boundary layers. Furthermore, we prove that the strong solution to Navier-Stokes equations converges to the Eulerian one in $C([0,T];H^1(\Omega))$ and L^\infty((0,T)\times\o), where $T$ is independent of the viscosity, provided that initial velocity is regular enough. Furthermore, rates of convergence are obtained also.Comment: 45page

Produção e composição química de cultivares de capim elefante no município de Altamira-PA.

bitstream/item/57537/1/Belem-BP1.pd

Extração, secagem e beneficiamento de sementes de espécies florestais nativas.

Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso

A posteriori error estimates for the virtual element method

An a posteriori error analysis for the virtual element method (VEM) applied to general elliptic problems is presented. The resulting error estimator is of residual-type and applies on very general polygonal/polyhedral meshes. The estimator is fully computable as it relies only on quantities available from the VEM solution, namely its degrees of freedom and element-wise polynomial projection. Upper and lower bounds of the error estimator with respect to the VEM approximation error are proven. The error estimator is used to drive adaptive mesh refinement in a number of test problems. Mesh adaptation is particularly simple to implement since elements with consecutive co-planar edges/faces are allowed and, therefore, locally adapted meshes do not require any local mesh post-processing

Genetic Barrier to Direct Acting Antivirals in HCV Sequences Deposited in the European Databank

Background & Aims: Development of resistance results from mutations in the viral genome, and the presence of selective drug pressure leads to the emergence of a resistant virus population. The aim of this study was to analyze the impact of genetic variability on the genetic barrier to drug resistance to DAAs. Methods: The genetic barrier was quantified based on the number and type of nucleotide mutations required to impart resistance, considering full-length HCV NS3, NS5A and NS5B regions segregated by genotype into subtypes 1a, 1b, 2a, 2b and 3a. This study analyzed 789 NS3 sequences, 708 sequences and 536 NS5B sequences deposited in the European Hepatitis C Virus Database, in the following resistance-associated positions: NS3: F43/I/L/ S/V, Q80K/R, R155K/G, A156G/S/T and D168A/C/E/G/H/N/T/V/Y; NS5A: L/M28A/T/V, Q30E/H/R, L31F/I/M/V, H58D or P58S and Y93C/F/H/N/S; NS5B: S282P/R/T, C316H/N/Y, S368T, Y448C/H, S556G/R, D559R. Results: Variants that require only one transversion in NS3 were found in 4 positions and include F43S, R80K, R155K/G and A156T. The genetic barrier to resistance shows subtypic differences at position 155 of the NS3 gene where a single transition is necessary in subtype 1a. In the NS5A gene, 5 positions where only one nucleotide change can confer resistance were found, such as L31M which requires one transversion in all subtypes, except in 0.28% of 1b sequences; and R30H, generated by a single transition, which was found in 10.25% of the sequences of genotype 1b. Other subtypic differences were observed at position 58, where resistance is less likely in genotype 1a because a transversion is required to create the variant 58S. For the NS5B inhibitors, the genetic barrier at positions conferring resistance was nearly identical in subtypes 1a and 1b, and single transitions or transversions were necessary in 5 positions to generate a drug-resistant variant of HCV. The positions C316Y and S556D required only one transition in all genotypes, Y448H and S556 G/N/R positions required only one transition for up to 98.8%of the sequences analyzed. A single variant in position 448 in genotype 1a is less likely to become the resistance variant 448H because it requires two transversions. Also, in the position 559D a transversion and a transition were necessary to generate the resistance mutant D559H. Conclusion: Results revealed that in 14 out of 16 positions, conversion to a drug-resistant variant of HCV required only one single nucleotide substitutions threatening direct acting antivirals from all three classes

Avaliação de espécies florestais e pastagens em sistemas silvipastoris em Paragominas, Pará, Brasil.

Propor modelos alternativos de uso-da-terra, econômicos e ecologicamente sustentáveis, tem sido um grande desafio da pesquisa agrícola na Amazônia. Os sistemas silvipastoris têm sido considerados promissores para integrar o cultivo arbóreo na pecuária e recuperar extensas áreas de pastagens degradadas da Amazônia. Entretanto, ainda carecem de uma base científica que suporte sua recomendação mais ampla. Em Paragominas-PA, foram estudados nove sistemas silvipastoris, de um hectare cada, constituídos da combinação binária de três espécies florestais (Schizolobium amazonicum, Bagassa guianensis e Eucalyptus terenticornis), plantadas em faixas de 6 m e afastadas de 12 m, com três pastagens (Brachiaria brizantha cv. Marandu, Brachiaria humidicola e Panicum maximum cv. Colonião/Brachiaria dictyoneura). Novilhos pastaram as parcelas experimentais simulando um sistema rotativo, com 14 dias de permanência e 42 dias de descanso. Foram medidos a altura e o diâmetro à altura do peito das espécies florestais, a massa de forragem e a proteína bruta das pastagens. Os componentes silvipastoris de melhor desempenho foram o Schizolobium amazonicum e Brachiaria brizantha cv Marandu. Dos pontos de vista florestal e pastoril, a combinação silvipastoril mais promissora foi Schizolobium amazonicum - Brachiaria brizantha cv Marandu