Turbulence driven particle transport in Texas Helimak

We analyze the turbulence driven particle transport in Texas Helimak (K. W. Gentle and Huang He, Plasma Sci. and Technology, 10, 284 (2008)), a toroidal plasma device with one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. For negative biased plasma discharges, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias the plasma has a reversed shear flow and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.Comment: 8 pages, 11 figure

Cosmic String in Scalar-Tensor Gravity

The gravitational properties of a local cosmic string in the framework of scalar-tensor gravity are examined. We find the metric in the weak-field approximation and we show that, contrary to the General Relativity case, the cosmic string in scalar-tensor gravitation exerces a force on non-relativistic, neutral test particle. This force is proportional to the derivative of the conformal factor $A^{2}(\phi)$ and it is always attractive. Moreover, this force could have played an important role at the Early Universe, although nowadays it can be neglegible. It is also shown that the angular separation $\delta\varphi$ remains unaltered for scalar-tensor cosmic strings.Comment: 15 pages, LATEX, no figure

Study of the impact of breeding seasons in the dynamics of dairy goat herds.

Abstract: The competitiveness in the animal production field has forced the smaller activities to be more efficient when compared to big business of the agro-industries. The dairy goat production is one of those market niches that need a better understand of its sector. For those reasons it has been proposed that by changing the number of reproduction seasons would increase income of the producers. The objectives of this study were to evaluate the impact of 1 or 2 annual reproductive cycles on production and economical health of dairy goats and to identify differences of production costs and revenues associated with changes in the herd dynamics as predicted by a mathematical model. A previously developed goat model using the System Dynamics approach to study long-term changes in the dynamics of the herd was used in these simulations. The model simulations used feeds, labor, and fixed costs as inputs and the outputs were revenues from milk production sales and sales of animals from all categories of the herd. The simulation time unit was ?month? and a long-term horizon of 10 years was considered for these simulations. The model was set up to simulate a freestall facility of a herd in equilibrium with 100 does in lactation. All parameters considered in this model assumed average values reported in production systems in the Southeast region of Brazil. The simulations results indicated that improvements of 10% in the fertility rate would increase the number animals in the herd up to 185% and 35% for one and two breeding season, respectively. Establishing a milk price as US$0.68 the break even for one and two breeding seasons was respectively US$0.62, and US$0.50, giving the systems with two breeding a capacity to support reductions on milk price up to 26% against 9% with one breeding season. When comparing the models with 1 or 2 breeding seasons was found that models with 2 breeding seasons was considerably more profitable and had a higher turnover than the model with 1 breeding season. The results indicate that the use of a second (artificial) breeding season might be an important management strategy to improve the efficiency of the dairy goat production systems. [Estudio del impacto de la estación reproductiva sobre la dinâmica de los rebaños lecheros]

A dairy goat model to study the impacts on herd dynamics.

The understanding of a dairy goat production system is crucial to establish a more competitive activity. Therefore, a simulation model was built to evaluate the dynamics of dairy goat herd under different scenarios of production. A System Dynamics approach was used to identify management policies that affect the behavior of the herd. All parameters considered in this model assumed average values reported in production systems in the Southeast region of Brazil. To simulate a herd in dynamic equilibrium, the culling and retention rates were used. Thereafter, simulations were performed based on changes in reproductive and mortality rates. All the simulations were planned to take the variation in herd development based on simple management strategies over 10 years of simulation. The dynamic equilibrium of 50 lactating does was obtained when fixed culling and retention rates of 20 and 70%, respectively, were assigned to the does after 36 months of simulation. A sensitivity analysis was made and indicated that an increase of 20% in the reproduction rates increased the number of animals in the herd in 56%. A decrease in the reproduction rate of 20% reduced the number of animals in 43%. A third simulation indicated that increasing mortality rate from 4 to 10% of the female kids decreased the number of lactating does by 36%. These results indicated that small changes in reproduction and mortality rates can considerably affect the dynamics of the herd, even though the herd may not be immediately affected because of the intrinsic delays in the system. This result is extremely important to justify the need of activity planning to consider the gap between a measurement taken and the consequences, preparing the producers to potential delays in the system. The use of mathematical models is important to understand the relationships between variables and the dynamic of the system and to assist in applying best management strategies to enhance productivity of dairy goats. [Modelo de cabras lecheras para evaluar el impacto de las estrategias de manejo en la dinámica del rebaño]

Cosmic String Wakes in Scalar-Tensor Gravities

The formation and evolution of cosmic string wakes in the framework of a scalar-tensor gravity are investigated in this work. We consider a simple model in which cold dark matter flows past an ordinary string and we treat this motion in the Zel'dovich approximation. We make a comaprison between our results and previous results obtained in the context of General Relativity. We propose a mechanism in which the contribution of the scalar field to the evolution of the wakes may lead to a cosmological observation.Comment: Replaced version to be published in the Classical and Quantum Gravit

Embryo production using epididymal sperm submitted to different selection methods and their influence on the embryo sex.

Proceedings of the 31st Annual Meeting of the Brazilian Embryo Technology Society (SBTE); Cabo de Santo Agostinho, PE, Brazil, August 17th to 19th, 2017. Abstract

Desempenho produtivo de cultivares de milho nas microrregiões de Paragominas, Belterra e Uruará no Estado do Pará.

O rendimento das lavouras de milho no Estado vem aumentando gradativamente, devido ao uso de variedades e de híbridos que vêm sendo desenvolvidas pela pesquisa, aliadas às práticas culturais mais modernas. Torna-se fundamental desenvolver atividades voltadas para a avaliação de variedades e híbridos, visando à seleção de materiais adaptados e com atributos agronômicos desejáveis. O objetivo foi avaliar híbridos pré - comerciais e comerciais de milho, visando recomendar cultivares de alta produtividade e adaptadas às condições ambientais do Nordeste e Oeste paraense. Utilizou-se o esquema de latice 7 x 7, com duas repetições. Na análise, foi detectada diferença estatística, a 1 % de probabilidade pelo teste F, para tratamentos, indicando a existência de diferenças genéticas entre as cultivares. A diferença mínima significativa (DMS t), a 1 %de probabilidade, foi de 1880 kg/ha de grãos. A amplitude de variação ficou entre 8.643 kg/ha (144 sacos) e 3.844 kg/ha (64 sacos), com média de 5.998 kg/ha (100 sacos). Os resultados sugerem a indicação e recomendação para plantio nessas regiões as cultivares: 2B604 HX (8.643), BRS 1060 (8.634), 30A86 HX (8.577), BH 9546 (8.306), P30F35 (7.993), 2B707 (7.926) e BRS 1055 (7.460) por apresentarem bom desempenho produtivo e outras características de interesse

Avaliação preliminar da viabilidade do consórcio de ovinos com fruteiras.

A possibilidade de associar a criação de ovinos à produção de fruteiras tem sido alvo de crescente interesse, especialmente nas áreas irrigadas do vale do São Francisco. Estudo em vários países indicam boas perspectivas para este tipo de associação pelo seu grande potencial em reduzir os custos de produção das fruteiras. Com esse objetivo, a Embrapa conduziu três ensaios preliminares na região Nordeste. O primeiro, consorciando ovinos com coqueirais da Baixada Litorânea de Sergipe, o segundo, com o cultivo de mangueiras Tommy Atkins, em latossolos irrigados do município de Curaçá, BA e o terceiro, com videiras irrigadas, no município de Petrolina, PE. Essas avaliações consideraram parâmetros de produtividade e de comportamento animal, de eficiência no controle da vegetação espontânea e de produtividade das fruteiras. Em todos os ensaios, os resultados observados indicam as boas perspectivas do sistema em controlar as ervas daninhas, reduzindo ou eliminando roçagens mecânicas, capinas manuais e aplicações de herbicidas, sem afetar a produtividade das fruteiras e de, adicionalmente, obter, na forma de produção de carne ovina, uma receita adicional ao empreendimento

Caracterização física e química de bananas orgânicas.

A banana apresenta importância social e econômica na dieta da população. A demanda por alimentos orgânicos vem crescendo ano a ano, tanto no Brasil como em outros países. Esse trabalho objetivou avaliar os atributos físicos e químicos de bananas orgânicas de diferentes cultivares. Os genótipos foram analisados quanto aos seguintes atributos físicos e físico-químicos: número de frutos por penca, diâmetro e comprimento do fruto, espessura da casca, massa do fruto com e sem casca, teor de sólidos solúveis totais, pH, acidez total titulável. Com exceção da cultivar Caipira, os genótipos apresentaram valores semelhantes ao dos cultivados em sistema convencional, para os atributos pH, acidez total, sólidos solúveis totais, embora com menor produção.pdf 248

Adaptabilidade e estabilidade de cultivares de milho no Meio-Norte brasileiro, na safra 2007/2008.

Durante a safra de 2007/2008, no Meio-Norte brasileiro, foram executados ensaios de milho em blocos casualizados com três repetições para a avaliação de 42 cultivares de milho (16 variedades e 26 híbridos), objetivando conhecer a adaptabilidade e a estabilidade desses materiais para fins de recomendação. Detectaram-se, nas análises de variância conjuntas, diferenças entre as cultivares e inconsistência no comportamento nos diferentes ambientes, no que se refere à produtividade de grãos. Os híbridos apresentaram, em média, produtividade de grãos (7.382 kg ha-1) 19,0 % maior que as variedades. Entre os híbridos de melhor adaptação, os que evidenciaram adaptabilidade ampla consolidaram-se como alternativas importantes para a agricultura regional, destacando-se, entre eles, os híbridos SHS 4070 e AG 7088. As variedades que revelaram adaptabilidade ampla, a exemplo das variedades BRS Caimbé e AL 25, entre outras, têm importância fundamental nos sistemas de produção dos agricultores familiares da região.bitstream/CPAMN-2010/24201/1/BOLP90.pd