Non BPS topological defect associated with two coupled real field

We investigate a stability equation involving two-component eigenfunctions which is associated with a potential model in terms of two coupled real scalar fields, which presents non BPS topological defect.Comment: Revtex, 6 pages, no figures. This work was presented in the XXII Brazilian National Meeting on Particles and Fields (October/2001), to appear at http://www.sbf.if.usp.b

A Representation of the Virasoro Algebra via Wigner-Heisenberg Algebraic Technique to Bosonic Systems

Using the Wigner-Heisenberg algebra for bosonic systems in connection with oscillators we find a new representation for the Virasoro algebra.Comment: Revised version. Revtex, 7 pages, no figures. This work was presented in the XXII Brazilian National Meeting on Particles and Fields (October/2001), to appear in Braz. J. of Phys., 33, 1 (2003

Idade ótima de abate em bracatingal tradicional.

Através de parâmetros de receita, custos e produtividade de produtores de bracatinga cultivada pelo sistema tradicional, na região de Colombo-PR, determinou- se a idade ótima econômica de abate dessa espécie. A metodologia utilizada foi do Valor Líquido Presente, que inclui todos os custos de produção de bracatinga, inclusive o custo de oportunidade da terra. A idade ótima econômica calculada foi a de sete anos. Esse resultado corrobora a intuição econômica dos produtores de bracating

Rentabilidade econômica de plantios florestais no Sul do Brasil.

O objetivo da presente pesquisa foi apresentar indicadores de custos, produtividade e rentabilidade econômica de espécies florestais de rápido crescimento para a região sul do Brasil. As atividades florestais analisadas foram: acácia-negra (Acacia mearnsii), bracatinga (Mimosa scabrella), erva-mate (Ilex paraguariensis) e eucalipto (Eucalyptus spp). Os dados foram obtidos de levantamentos junto a produtores rurais dos Estados do Paraná, Santa Catarina e Rio Grande do Sul. A análise abrange um período de 7 anos para as quatro atividades. A rentabilidade econômica foi medida através da Taxa Interna de Retorno (TIR) e do Valor Presente Líquido (VPL). Adicionalmente utilizou-se o Valor Equivalente Anual (VEA) para a visualização da rentabilidade anual das respectivas alternativas de produção. Os resultados apontam para os altos custos de implantação da acácia-negra (R$403,88/ha), erva-mate (R$ 1.060,70/ha) e eucalipto (R$518,10/ha) comparados com a bracatinga com apenas (R$ 11,40/ha ). A produtividade médias/ha.ano foi de: acácia-negra (2,2 t de casca e 25,7 st. de madeira), bracatinga (25 m estereos de madeira), eucalipto (35 m3 de madeira) e erva-mate (350 arrobas de erva verde). As Taxas Internas de Retorno (TIR) foram: acácia-negra (46,01%), bracatinga (38,88%), erva-mate (29,57%) e eucalipto (21,83%). O VPL para as quatro atividades foi: acácia-negra (R$2.400,35/ha), erva-mate (R$ 1.679,12/ha), eucalipto (R$820,35/ha) e bracatinga (R$ 70,12/ha). Por sua vez, o critério do VEA com o mesmo ordenamento do VPL, apresentou as seguintes rentabilidades anuais: acácia-negra (R$429,99/ha), erva-mate (R$ 300,79/ha), eucalipto (R$146,95/ha) e a bracatinga com apenas (R$ 12,56/ha). Estes indicadores comprovam que todas as atividades analisadas são economicamente rentáveis, poderão ser utilizadas isoladamente ou combinadas e que, além do aumento do emprego e da renda apresentam importante contribuição na preservação ambiental e melhoria dos recursos naturais, formando a chamada poupança verde dos produtores rurais.Pôster

Rentabilidade da acácia-negra, bracatinga, eucalipto e erva-mate para produtores rurais do Sul do Brasil.

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Consumption orientations may support (or hinder) transitions to more plant-based diets

There have been increasing calls for triggering and sustaining a large-scale transition toward healthier and more sustainable food systems. To help materialize this transition, the present work aims to inform efforts for developing, marketing and promoting plant-based meals and plant-forward lifestyles, following a consumption-focused approach. The findings (Nparticipants = 1600, Portugal; 52.6% female, Mage = 48.30) allowed to identify trends and differences on three sets of variables – (a) current eating habits (i.e., meat, fish, and plant-based meals), (b) consumer willingness to change (i.e., reduce meat consumption, follow a plant-based diet, maintain the status quo), and (c) enablers for eating plant-based meals more often (i.e., capability, opportunity, motivation) –, considering consumer orientations toward consumption in general, and food consumption in particular. Taken together, the results suggested that some consumption orientations were aligned with the transition to more plant-based diets (e.g., food orientation toward naturalness), others were open to – but not yet materialized in – the transition (e.g., general orientation toward consumption as exploration), and still others were in tension with the transition (e.g., food orientation toward pleasure). The discussion calls for developing and testing pathways to reduce meat consumption and increase plant-based eating which capture and build upon a range of consumption orientations, rather than against them.info:eu-repo/semantics/acceptedVersio

Turing machines can be efficiently simulated by the General Purpose Analog Computer

The Church-Turing thesis states that any sufficiently powerful computational model which captures the notion of algorithm is computationally equivalent to the Turing machine. This equivalence usually holds both at a computability level and at a computational complexity level modulo polynomial reductions. However, the situation is less clear in what concerns models of computation using real numbers, and no analog of the Church-Turing thesis exists for this case. Recently it was shown that some models of computation with real numbers were equivalent from a computability perspective. In particular it was shown that Shannon's General Purpose Analog Computer (GPAC) is equivalent to Computable Analysis. However, little is known about what happens at a computational complexity level. In this paper we shed some light on the connections between this two models, from a computational complexity level, by showing that, modulo polynomial reductions, computations of Turing machines can be simulated by GPACs, without the need of using more (space) resources than those used in the original Turing computation, as long as we are talking about bounded computations. In other words, computations done by the GPAC are as space-efficient as computations done in the context of Computable Analysis

Análise preliminar da exploração florestal no Centro-sul do Brasil.

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Chemical composition of bee pollen

Bee pollen, usually used as an important source of nutrients and micronutrients for the young bees in the hive, is also an important food for humans. This product is very rich in proteins, lipids, free sugars, carbohydrates, and it contains trace amounts of minerals, phenolic acids, flavonoids and a good range of vitamins. A brief look at bee pollen composition, it is easily recognised that it is a balanced food that can be used as a stand-alone food or as a nutritional supplement or even as a medicinal product. Several bioactivities, due to some of these compounds, were studied in bee pollen samples from different floral sources and the results conduce to important properties. The amount and diversity of micronutrients could induce vast benefits if used for health purposes following a complete risk assessment. Nevertheless, the results pointing towards the encouraged use of bee pollen, the risk assessment of some floral species containing toxic compounds has not been fully studied to insure the safety of consumption for all the gathered flowers, so this will also be discussed in this chapter. Admiration for its goodness and medicinal properties, bee pollen has been consumed for centuries, however, currently the efficacy and safety for all consumed products, foods, supplements or medicines is an important tool to guarantee correct quality control and essential to add value to the product. To summarise, in this chapter we will put the situation of gaps in bee pollen research into some kind of perspective, outlining some important points and discussing in more depth the implications of collecting samples, chemical composition and risk assessment.info:eu-repo/semantics/publishedVersio

Análise do aproveitamento econômico do resíduo florestal.

Através de dados de pesquisas existentes sobre o conteúdo de nutrientes em resíduos florestais de Eucalyptus e Pinus, investigou-se a vantagem econômica da utilização dos resíduos, como energia ou como reciclagem de nutrientes no solo. Os resultados mostraram que o emprego dos resíduos florestais como energia se apresenta mais econômico, compensando, inclusive, a reposição de nutrientes através da adubação química. O baixo valor da equivalência da fitomassa em nutrientes, em relação ao de sua transformação em energia, e a proporção desfavorável dos preços de fertilizantes para o preço de energia, foram os principais fatores que afetaram essa economicidade