12,718 research outputs found

    Fractal index, central charge and fractons

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    We introduce the notion of fractal index associated with the universal class hh of particles or quasiparticles, termed fractons, which obey specific fractal statistics. A connection between fractons and conformal field theory(CFT)-quasiparticles is established taking into account the central charge c[ν]c[\nu] and the particle-hole duality ν1ν\nu\longleftrightarrow\frac{1}{\nu}, for integer-value ν\nu of the statistical parameter. In this way, we derive the Fermi velocity in terms of the central charge as vc[ν]ν+1v\sim\frac{c[\nu]}{\nu+1}. The Hausdorff dimension hh which labelled the universal classes of particles and the conformal anomaly are therefore related. Following another route, we also established a connection between Rogers dilogarithm function, Farey series of rational numbers and the Hausdorff dimension.Comment: latex, 12 pages, To appear in Mod. Phys. Lett. A (2000

    Analytic Torsion on Hyperbolic Manifolds and the Semiclassical Approximation for Chern-Simons Theory

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    The invariant integration method for Chern-Simons theory for gauge group SU(2) and manifold \Gamma\H^3 is verified in the semiclassical approximation. The semiclassical limit for the partition function associated with a connected sum of hyperbolic 3-manifolds is presented. We discuss briefly L^2 - analytical and topological torsions of a manifold with boundary.Comment: 12 pages, LaTeX fil

    Efeito da aplicação de tratamentos pós-colheita na conservação de raízes de mandioca.

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    O objetivo deste trabalho foi avaliar a eficiência do revestimento com fécula de mandioca ou parafina na conservação da qualidade pós-colheita de raízes de mandioca armazenadas sob condições ambiente por 9 dias. Após a lavagem e sanitização, as raízes foram revestidas com fécula de mandioca na concentração de 5% ou parafina aquecida a 60 oC e acomodadas em bandejas de poliestireno expandido ? EPS (Isopor®) mantidas sob temperatura ambiente. Como controle foram utilizadas raízes sem recobrimento. As análises foram realizadas diariamente, durante 9 dias de armazenamento, sendo avaliada a perda de massa, tempo de cozimento, aparência visual, umidade, pH e acidez titulável. Por meio de identificação visual, observou-se que o escurecimento vascular foi o principal sintoma de deterioração nas mandiocas. Nas raízes que não sofreram qualquer tratamento e naquelas submetidas ao tratamento com revestimento de fécula, os sintomas de deterioração apareceram no terceiro dia de armazenamento, em cerca de 50% das raízes. Nas mandiocas submetidas ao tratamento com revestimento de parafina, os primeiros sintomas internos foram observados no quarto dia de armazenamento, em 33,3% das raízes analisadas. O revestimento com parafina foi responsável também por menor perda de massa e menor tempo de cozimento das raízes ao longo de todo o período de armazenamento. Para a análise de umidade, observaram-se teores variando de 57,9% a 64,7%. Para as análises de pH e acidez titulável verificou-se oscilação nos resultados ao longo do período de armazenamento para os três tratamentos estudados.bitstream/item/31764/1/BPD74.pdfVersão eletrônica. 1ª impressão: 2010

    Welfare and Convergence Speed in the Ramsey Model under two Classes of Gorman Preferences

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    Using a one-sector, discrete-time Ramsey model, we analyze and compare the implications for welfare, capital accumulation, and speed of convergence to the steady state of two classes of utility functions that represent Gorman preferences, namely homothetic and Stone\u2013Geary preferences. For identical economies, we show that the preference structure does not affect only the capital dynamics and social welfare but also the speed of convergence to the steady-state equilibrium

    Os aningais: um tipo de vegetação "quase extinta nas cidades amazônicas".

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    Os aningais são compostos principalmente pela planta conhecida regionalmente como Aninga (Montrichardia arborescens Schott), uma Araceae que pode atingir 3 a 4 m de altura ocorrendo em densa sinúsia quase monoespecífica caracterizando a paisagem aningal. O objetivo desse trabalho é alertar para a destruição dos remanescentes de aningais nessas cidades e identificar as espécies que ocorre nessa região

    Polo-like kinase 4 controls centriole duplication but does not directly regulate cytokinesis.

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    Centrioles organize the centrosome, and accurate control of their number is critical for the maintenance of genomic integrity. Centrioles duplicate once per cell cycle, and duplication is coordinated by Polo-like kinase 4 (Plk4). We previously demonstrated that Plk4 accumulation is autoregulated by its own kinase activity. However, loss of heterozygosity of Plk4 in mouse embryonic fibroblasts has been proposed to cause cytokinesis failure as a primary event, leading to centrosome amplification and gross chromosomal abnormalities. Using targeted gene disruption, we show that human epithelial cells with one inactivated Plk4 allele undergo neither cytokinesis failure nor increase in centrosome amplification. Plk4 is shown to localize exclusively at the centrosome, with none in the spindle midbody. Substantial depletion of Plk4 by small interfering RNA leads to loss of centrioles and subsequent spindle defects that lead to a modest increase in the rate of cytokinesis failure. Therefore, Plk4 is a centriole-localized kinase that does not directly regulate cytokinesis

    Development of Coleomegilla maculata De Geer (Coleoptera: coccinellidae) with prey and artificial diet.

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    Coleomegilla maculata De Geer (Coleoptera: Coccinellidae) is an important predator and has the potential to be used as a biological control agent of insect pests of maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench]. This study aimed to evaluate the development of C. maculata larvae fed eggs Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) alone or associated with artificial diet, eggs of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) and nymphs of Schizaphis graminum (Rondani) (Hemiptera: Aphididae). The experiment was conducted in a complete randomized design with four replications, each with 10 larvae of C. maculata in an acclimatized room (25 ± 1 ºC, 70 ± 10% RH and 12 hours photophase). The duration of the stages of C. maculata was similar in all treatments, except for one that used nymphs of S. graminum, resulting in a shorter period for the larval stage. The viability of larval, prepupal and pupal stages and larval to adult C. maculata was high and similar in all treatments. No effect of diets on the weight of C. maculata adults occurred, except for the heavier insects fed on eggs of A. kuehniella, whose males and females weighed 9.8 ± 0.3 mg and 13.3 ± 0.5 mg, respectively
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