8,346 research outputs found

    A conjugate for the Bargmann representation

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    In the Bargmann representation of quantum mechanics, physical states are mapped into entire functions of a complex variable z*, whereas the creation and annihilation operators a^\hat{a}^\dagger and a^\hat{a} play the role of multiplication and differentiation with respect to z*, respectively. In this paper we propose an alternative representation of quantum states, conjugate to the Bargmann representation, where the roles of a^\hat{a}^\dagger and a^\hat{a} are reversed, much like the roles of the position and momentum operators in their respective representations. We derive expressions for the inner product that maintain the usual notion of distance between states in the Hilbert space. Applications to simple systems and to the calculation of semiclassical propagators are presented.Comment: 15 page

    Stabilizing effect of montmorillonite on acerola juice anthocyanins.

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    Made available in DSpace on 2018-05-22T00:53:44Z (GMT). No. of bitstreams: 1 ART18006.pdf: 761892 bytes, checksum: cd1a73015568731442064ac3c322797b (MD5) Previous issue date: 2018-03-23bitstream/item/177375/1/ART18006.pd

    Produtividade e qualidade de grãos em arroz de terras altas na região Meio-Norte do Brasil.

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    Foram realizados sete Ensaios Comparativos avançados nos municípios de Teresina, Baixa Grande do Ribeiro, Bom Jesus e Palmeira do Piauí, no Estado do Piauí, e em Anapurus, Balsas e Sambaíba, No Estado do Marnhão, no ano agrícola de 1998/99, para avaliar quatorze linhagens avançadas e quatro cultivares (testemunhas) oriundas do Programa de Melhoramento Genético de Arroz de Terras Altas, coordenado pela Embrapa Arroz e Feijão.bitstream/item/35791/1/Bol29.pd

    The Apparent Fractal Conjecture: Scaling Features in Standard Cosmologies

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    This paper presents an analysis of the smoothness problem in cosmology by focussing on the ambiguities originated in the simplifying hypotheses aimed at observationally verifying if the large-scale distribution of galaxies is homogeneous, and conjecturing that this distribution should follow a fractal pattern in perturbed standard cosmologies. This is due to a geometrical effect, appearing when certain types of average densities are calculated along the past light cone. The paper starts reviewing the argument concerning the possibility that the galaxy distribution follows such a scaling pattern, and the premises behind the assumption that the spatial homogeneity of standard cosmology can be observable. Next, it is argued that to discuss observable homogeneity one needs to make a clear distinction between local and average relativistic densities, and showing how the different distance definitions strongly affect them, leading the various average densities to display asymptotically opposite behaviours. Then the paper revisits Ribeiro's (1995: astro-ph/9910145) results, showing that in a fully relativistic treatment some observational average densities of the flat Friedmann model are not well defined at z ~ 0.1, implying that at this range average densities behave in a fundamentally different manner as compared to the linearity of the Hubble law, well valid for z < 1. This conclusion brings into question the widespread assumption that relativistic corrections can always be neglected at low z. It is also shown how some key features of fractal cosmologies can be found in the Friedmann models. In view of those findings, it is suggested that the so-called contradiction between the cosmological principle, and the galaxy distribution forming an unlimited fractal structure, may not exist.Comment: 30 pages, 2 figures, LaTeX. This paper is a follow-up to gr-qc/9909093. Accepted for publication in "General Relativity and Gravitation

    Phosphites for the control of anthracnose in common bean.

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    The objective of this work was to evaluate the effect of phosphites in the protection of common bean (Phaseolus vulgaris) against anthracnose. Different phosphite formulations were evaluated by quantifying peroxidase and polyphenol oxidase activity, total phenols, and lignin content. The treatments consisted of sprayings, in the V4, R5, and R7 stages, with: the K, Zn, Mn, K+Mn, K+salicyclic acid, and Cu phosphites; salicylic acid; acibenzolar-S-methyl; and the fungicide azoxystrobin; besides a control, without sprayings. The area under the disease progress curve was lower in plants that received applications of the K and Mn phosphites, whose values ranged between 74 and 81%, compared with the control. The K, Zn, and K+salicyilic acid phosphites were effective in controlling the disease. In addition, disease severity was lower with the application of the K, Zn, and Mn phosphites than with the control. Enzyme (peroxidases and polyphenol oxidases) activity and levels of soluble phenols were higher in common bean plants treated with the K and Mn phosphites, although no change was detected in the levels of soluble lignin in the same tissue. Phosphite application reduces the severity of the disease, can enhance enzymatic activity, and is an effective alternative for the control of anthracnose in common bean

    Qualidade do sêmen em tilápia do Nilo (Oreochromis niloticus), alimentadas com dietas contendo diferentes níveis de vitamina C.

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    A vitamina C atua na proteção de danos celulares provocados pelos radicais livres, sendo a suplementação considerada essencial para a maioria das espécies de peixes, uma vez que não a sintetizam em função da ausência da enzima L-gulonolactona oxidase. Assim, avaliou-se o efeito da suplementação de 0, 75, 150 e 225 mg de vitamina C kg-1 de ração na qualidade do sêmen em tilápias do Nilo (Oreochromis niloticus). Os parâmetros quali-quantitativos do sêmen não foram influenciados pela suplementação de vitamina C, exceto a motilidade progressiva que aumentou linearmente com adição de vitamina C. Conclui-se que os reprodutores de tilápias do Nilo devem ser suplementados com 225 mg de vitamina C kg-1 de ração

    Avaliação de clones de mandioca no Município de Vilhena-RO.

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    A mandioca (Manihot esculenta Crantz) é cultivada em todas as regiões tropicais e é considerada uma das culturas mais eficientes na produção de carboidratos entre as plantas superiores (Howeler, 1981). Estima-se que cerca de 400 milhões de pessoas dependem diretamente desta planta como alimento básico (CIAT,1988). A razão de sua ampla difusão se deve a grande capacidade de adaptação a diferentes condições de clima e solo (Conceição, 1986). Sua importância se dá principalmente pelo fato de ser um dos alimentos mais baratos utilizados pelo homem na forma fresca e/ou na forma seca como farinha. A mandioca é o principal produto agrícola de Rondônia, em importância econômica e social (IBGE, 2011). A cultura da mandioca representa papel fundamental para geração de renda e na segurança alimentar de diversos produtores rurais, familiares, no estado. Ademais, a cultura apresenta um grande potencial de expansão de produção, visto que grande parte da farinha e fécula consumidas atualmente em Rondônia é originária de outros estados como Acre e Paraná. Em Rondônia, a produção de raízes de mandioca, na safra 2010/2011, é estimada em 517.275 toneladas, plantada em uma área de 30.232 ha, proporcionando um rendimento médio esperado de 17.110 kg/ha, superior à média nacional de 14.785 kg/ha (IBGE, 2011); que é, entretanto, significativamente inferior às produtividades de estados como Paraná, São Paulo e Mato Grosso do Sul.Melhoramento genético. Resumo n. 264
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