Baryon loading and the Weibel instability in gamma-ray bursts

The dynamics of two counter-streaming electron-positron-ion unmagnetized plasma shells with zero net charge is analyzed in the context of magnetic field generation in GRB internal shocks due to the Weibel instability. The effects of large thermal motion of plasma particles, arbitrary mixture of plasma species and space charge effects are taken into account. We show that, although thermal effects slow down the instability, baryon loading leads to a non-negligible growth rate even for large temperatures and different shell velocities, thus guaranteeing the robustness and the occurrence of the Weibel instability for a wide range of scenarios.Comment: 6 pages, 4 figures. Accepted for publication in MNRA

Impact of water saving irrigation systems on water use, growth and yield of irrigated lowland rice

To meet the growing demand for food and other needs from an increasing population, the rice production in Sri Lanka, which was 3.87 million tonnes in 2008, has to be increased to 4.2 million tonnes by the year 2020. This requirement could be achieved by increasing productivity and/or by increasing the cultivated extent. In 2008, about 77 % and 68 % of the total paddy land extent was cultivated with either partial or full irrigation during the maha and yala seasons, respectively. A considerable extent of paddy land was either not cultivated or cultivated for other crops due to the scarcity of water in the dry and intermediate zones. Furthermore, with increased competition for water for domestic and industrial needs and climate change, there will be further reductions in the availability of water for rice cultivation. Conserving irrigation water would increase the cultivated extent of land while reducing the probability of ate season water-stress in the cultivated rice crop. We studied the impact of different soil water regimes on water use, nutrient uptake, growth and grain yield of 3 – 3� age lowland rice at the Rice Research and Development Institute, Batalagoda, Ibbagamuwa. There was no significant difference in the grain yield in rice when grown under either saturated or flooded conditions, but the yield decreased significantly with alternate wetting and drying. However, under saturated conditions, the irrigation water requirement was significantly lower than the flooded condition. The lowest irrigation water requirement was recorded with saturated to dry conditions. The irrigation water requirement under flooded conditions, when compared with the saturated condition, increased by 39 % during the yala season. During the maha season, even though the total irrigation requirement was lower, when compared to saturated conditions, four times more irrigation water was required under flooded conditions. There was a significant increase in plant dry matter production and leaf N (nitrogen) under saturated conditions, when compared with conventional flooded conditions. These findings suggest that when soil water is maintained at a saturated level in lowland rice, a considerable amount of irrigation water could be saved without sacrificing grain yield.Length: pp.57-64RiceIrrigated farmingWater conservationIrrigation systems

Inovação no desenvolvimento de embalagens para frutas e vegetais in natura

A maioria das pessoas não se dá conta que as embalagens para hortifruticolas acondicionam seres vivos. Estas embalagens possuem significados e usos tão específicos que mereceriam estar catalogadas numa categoria particular e não na categoria genérica de embalagens para alimentos. Os seres vivos que acondicionam pertencem a diversos tipos, espécies e categorias, e possuem qualidades essenciais e características organolépticas, sensoriais únicas. Por isto, as embalagens para hortofruticolas, e o seu processo de desenvolvimento, devem que respeitar o caráter único de cada produto. O desrespeito a este caráter único tem contribuído fortemente para que as embalagens reduzam o tempo de vida útil das frutas, legumes e verduras e aumentem as perdas pós-colheita. As embalagens não devem ser genéricas. Contudo, esta não tem sido a visão dos projetistas e dos produtores industriais das embalagens para hortifruticolas. A Divisão de Desenho Industrial do Instituto Nacional de Tecnologia criou um processo – e método – inovador de design para o projeto de embalagens para frutas, legumes e verduras, que respeita as singularidades de cada tipo de produto. Apresentamos este processo e método neste artigo. Submetemos a avaliações - sob o ponto de vista de redução das perdas -, estas novas embalagens em comparação com todas as outras existentes no Brasil. Escolhemos as embalagens para caquis (Diospyros kaki) para demonstrar estas avaliações porque no Brasil perde-se, nos processos de pós-colheita, cerca de 80 % de todo o caqui plantado.ABSTRACT: Most people do not realize that the packaging for horticultural contained living beings. These packages have specific meanings and uses that deserve to be cataloged in a particular category and not in the general category of food packaging. Living beings contained therein belong to various types, species and categories, and have unique essential qualities, organolep_c properties and sensory characteristics. Therefore, the packaging for horticultural, and its development process, must respect the unique character of each product. Failure to comply with this unique character have contributed strongly to the packaging reduce the useful life of fruits and vegetables and increase post-harvest losses. Packaging must not be generic. However, this has not been the vision of designers and industrial producers of packaging for horticultural. We present this process and method in this paper. We submit to assessments these new packages compared with all other existing in Brazil, from the point of view reducing losses. We chose the packaging for persimmons (Diospyros kaki) to demonstrate these assessments because in Brazil in the post-harvest processes about 80% of all planted persimmon are lost.info:eu-repo/semantics/publishedVersio

Modelo para estimativa de custos de produção de culturas irrigadas: caso do milho irrigado por pivô central.

Descrição do modelo; Custos de produção; Custo da horta de máquinas, equipamentos e mão-de-obra; Custo de hora de pivô central; Custo de desmatamento, correção e conservação de solo; Custo de produção de milho irrigado; Resultado operacional.bitstream/item/71402/1/CPAMN-CIR.-TEC.-1-89.pd