Complete high-precision entropic sampling

Monte Carlo simulations using entropic sampling to estimate the number of configurations of a given energy are a valuable alternative to traditional methods. We introduce {\it tomographic} entropic sampling, a scheme which uses multiple studies, starting from different regions of configuration space, to yield precise estimates of the number of configurations over the {\it full range} of energies, {\it without} dividing the latter into subsets or windows. Applied to the Ising model on the square lattice, the method yields the critical temperature to an accuracy of about 0.01%, and critical exponents to 1% or better. Predictions for systems sizes L=10 - 160, for the temperature of the specific heat maximum, and of the specific heat at the critical temperature, are in very close agreement with exact results. For the Ising model on the simple cubic lattice the critical temperature is given to within 0.003% of the best available estimate; the exponent ratios $\beta/\nu$ and $\gamma/\nu$ are given to within about 0.4% and 1%, respectively, of the literature values. In both two and three dimensions, results for the {\it antiferromagnetic} critical point are fully consistent with those of the ferromagnetic transition. Application to the lattice gas with nearest-neighbor exclusion on the square lattice again yields the critical chemical potential and exponent ratios $\beta/\nu$ and $\gamma/\nu$ to good precision.Comment: For a version with figures go to http://www.fisica.ufmg.br/~dickman/transfers/preprints/entsamp2.pd

Efeito da temperatura de condicionamento sobre a digestibilidade da proteina bruta e metabolizabilidade de dietas para frangos de corte.

Sabe-se que o tratamento térmico do alimento pode melhorar seu aproveitamento, sendo a influência do processamento sobre a digestibilidade o principal modo de ação (4). A peletização da ração aumenta a digestibilidade das frações da dieta pela ação mecânica e pela temperatura do processo. Os processos térmicos também promovem alterações das estruturas terciárias naturais das proteínas, facilitando sua digestão (2). A peletização proporciona um aumento do valor energético dos nutrientes, sendo uma alternativa viável para dietas de frangos de corte em termos de aumento da energia metabolizável da dieta. Com isso, objetivou-se avaliar o efeito de diferentes temperaturas de condicionamento sobre o coeficiente de metabolizabilidade aparente da matéria seca (CMAMS) e o coeficiente de digestibilidade aparente da proteína bruta (CDPBap)

Wang-Landau sampling: Improving accuracy

In this work we investigate the behavior of the microcanonical and canonical averages of the two-dimensional Ising model during the Wang-Landau simulation. The simulations were carried out using conventional Wang-Landau sampling and the $1/t$ scheme. Our findings reveal that the microcanonical average should not be accumulated during the initial modification factors \textit{f} and outline a criterion to define this limit. We show that updating the density of states only after every $L^2$ spin-flip trials leads to a much better precision. We present a mechanism to determine for the given model up to what final modification factor the simulations should be carried out. Altogether these small adjustments lead to an improved procedure for simulations with much more reliable results. We compare our results with $1/t$ simulations. We also present an application of the procedure to a self-avoiding homopolymer

Aerosol number fluxes over the Amazon rain forest during the wet season

Number fluxes of particles with diameter larger than 10 nm were measured with the eddy covariance method over the Amazon rain forest during the wet season as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) campaign 2008. The primary goal was to investigate whether sources or sinks dominate the aerosol number flux in the tropical rain forest-atmosphere system. During the measurement campaign, from 12 March to 18 May, 60% of the particle fluxes pointed downward, which is a similar fraction to what has been observed over boreal forests. The net deposition flux prevailed even in the absolute cleanest atmospheric conditions during the campaign and therefore cannot be explained only by deposition of anthropogenic particles. The particle transfer velocity v(t) increased with increasing friction velocity and the relation is described by the equation v(t) = 2.4x10(-3)xu(*) where u(*) is the friction velocity. Upward particle fluxes often appeared in the morning hours and seem to a large extent to be an effect of entrainment fluxes into a growing mixed layer rather than primary aerosol emission. In general, the number source of primary aerosol particles within the footprint area of the measurements was small, possibly because the measured particle number fluxes reflect mostly particles less than approximately 200 nm. This is an indication that the contribution of primary biogenic aerosol particles to the aerosol population in the Amazon boundary layer may be low in terms of number concentrations. However, the possibility of horizontal variations in primary aerosol emission over the Amazon rain forest cannot be ruled out.National Institute for Research in the Amazon (INPA)LBA infrastructure teamCNPq/MCT Millennium Institute ProgramFAPES

A comparison of dry and wet season aerosol number fluxes over the Amazon rain forest

Vertical number fluxes of aerosol particles and vertical fluxes of CO(2) were measured with the eddy covariance method at the top of a 53 m high tower in the Amazon rain forest as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment. The observed aerosol number fluxes included particles with sizes down to 10 nm in diameter. The measurements were carried out during the wet and dry season in 2008. In this study focus is on the dry season aerosol fluxes, with significant influence from biomass burning, and these are compared with aerosol fluxes measured during the wet season. Net particle deposition fluxes dominated in daytime in both seasons and the deposition flux was considerably larger in the dry season due to the much higher dry season particle concentration. The particle transfer velocity increased linearly with increasing friction velocity in both seasons. The difference in transfer velocity between the two seasons was small, indicating that the seasonal change in aerosol number size distribution is not enough for causing any significant change in deposition velocity. In general, particle transfer velocities in this study are low compared to studies over boreal forests. The reasons are probably the high percentage of accumulation mode particles and the low percentage of nucleation mode particles in the Amazon boundary layer, both in the dry and wet season, and low wind speeds in the tropics compared to the midlatitudes. In the dry season, nocturnal particle fluxes behaved very similar to the nocturnal CO(2) fluxes. Throughout the night, the measured particle flux at the top of the tower was close to zero, but early in the morning there was an upward particle flux peak that is not likely a result of entrainment or local pollution. It is possible that these morning upward particle fluxes are associated with emission of primary biogenic particles from the rain forest. Emitted particles may be stored within the canopy during stable conditions at nighttime, similarly to CO(2), and being released from the canopy when conditions become more turbulent in the morning.National Institute for Research in the Amazon (INPA)LBACNPq/MCTFAPES

Supressão dos maciços florestais no município de Araucária, PR entre os anos de 2005 e 2012.

Resumo

A busca pela excelência laboratorial: acreditação de ensaios do Laboratório de Análise de Sementes da Embrapa Milho e Sorgo baseada na Norma ISO/IEC 17025: 2005.

A acreditação na ISO/IEC 17025:2005, com o conseqüente reconhecimento da competência técnica para realizar ensaios e aceitação dos resultados obtidos, é um instrumento eficaz para a remoção de barreiras técnicas ao comércio nacional e internacional. A qualidade comparável de resultados forma a base da aceitação mútua entre os países que adotam essa norma, além de se evitar a duplicação de testes, reduzindo o desperdício de tempo e recursos. A metodologia para implantação do sistema de gestão da qualidade (SG) no LAS da Embrapa Milho e Sorgo foi baseada na aplicação de ações de gestão, levantamento das necessidades, sensibilização e capacitação da equipe, documentação e validação do sistema de gestão da qualidade. Desde o ano de 2003, o LAS iniciou a implantação do SG com resultados parciais e lentos. A parceria entre duas Unidades da Embrapa (Embrapa Meio Ambiente, Unidade da Embrapa certificada desde 2005 na ISO 9001 :2000, e Milho e Sorgo) mostrou-se bastante eficaz, o que tomou possível a participação da Embrapa Milho e Sorgo num projeto corporativo para melhoria da gestão organizacional, onde essas experiências foram difundidas e compartilhadas. O parecer final sobre o processo de auditoria foi que o LAS da Embrapa Milho e Sorgo demonstrou ter instalações, equipamentos, pessoal e competência para realizar as análises do escopo do credenciamento e comprovou a implantação de um sistema de gestão da qualidade baseado na Norma NBR ISO /IEC 17025. A equipe auditora do LASO /LANAGRO /MG recomendou que seja concedido o credenciamento no RENASEM solicitado pelo laboratório

Enzymatic kinetic resolution of (RS)-1-(Phenyl)ethanols by Burkholderia cepacia lipase immobilized on magnetic nanoparticles

Lipase from Burkholderia cepacia immobilized on superparamagnetic nanoparticles using adsorption and chemisorption methodologies was efficiently applied as recyclable biocatalyst in the enzymatic kinetic resolution of (RS)-1-(phenyl)ethanols via transesterification reactions. (R)-Esters and the remaining (S)-alcohols were obtained with excellent enantiomeric excess (> 99%), which corresponds to a perfect process of enzymatic kinetic resolution (conversion 50%, E > 200). The transesterification reactions catalysed with B. cepacia lipase immobilized by the glutaraldehyde method showed the best results in terms of reusability, preserving the enzyme activity (conversion 50%, E > 200) for at least 8 successive cycles.A lipase proveniente da Burkholderia cepacia imobilizada em nanopartículas superparamagnéticas usando diferentes metodologias de imobilização (adsorção e quimiosorção) foi eficientemente aplicada como biocatalisador reciclável na resolução cinética de (RS)-1-(fenil)etanols através de reações de transesterificação. Os (R)-ésteres e os (S)-alcoóis foram obtidos com excelente excesso enantiomérico (> 99%), o que corresponde a um perfeito processo de resolução cinética enzimática (conversão 50%, E > 200). As reações de transesterificação catalisadas pela lipase de B. cepacia imobilizada pela metodologia com glutaraldeído apresentaram os melhores resultados em termos de conversão após 8 ciclos de reação.FAPESPCNPqPETROBRA

Mosca-dos-chifres: aspectos bio-ecológicos, importância econômica, interações parasito-hospedeiro e controle.

Esta publicação teve por objetivo apresentar aspectos relativos à biologia e às interações existentes entre a presença da mosca-dos-chifres sobre seu hospedeiro preferencial, os bovinos, bem como os métodos de avaliação do grau de parasitismo e controle da mosca-dos-chifres.bitstream/item/24807/1/Cot302-mosca-dos-chifres.pd