4,309 research outputs found

    Output functions and fractal dimensions in dynamical systems

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    We present a novel method for the calculation of the fractal dimension of boundaries in dynamical systems, which is in many cases many orders of magnitude more efficient than the uncertainty method. We call it the Output Function Evaluation (OFE) method. The OFE method is based on an efficient scheme for computing output functions, such as the escape time, on a one-dimensional portion of the phase space. We show analytically that the OFE method is much more efficient than the uncertainty method for boundaries with D<0.5D<0.5, where DD is the dimension of the intersection of the boundary with a one-dimensional manifold. We apply the OFE method to a scattering system, and compare it to the uncertainty method. We use the OFE method to study the behavior of the fractal dimension as the system's dynamics undergoes a topological transition.Comment: Uses REVTEX; to be published in Phys. Rev. Let

    The Vampire and the FOOL

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    This paper presents new features recently implemented in the theorem prover Vampire, namely support for first-order logic with a first class boolean sort (FOOL) and polymorphic arrays. In addition to having a first class boolean sort, FOOL also contains if-then-else and let-in expressions. We argue that presented extensions facilitate reasoning-based program analysis, both by increasing the expressivity of first-order reasoners and by gains in efficiency

    The role of organizational structure and deviant status in employees’ reactions to and acceptance of workplace deviance

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    Purpose: To examine the role of deviant status (lower vs. higher rank) and organizational structure (vertical vs. horizontal) on individuals’ responses to workplace deviance. Design/methodology/approach: Two studies (N = 472) were designed to examine the role of deviant status and organizational structure in responses to workplace deviance. Study 1 (N = 272) manipulated deviant status and organizational structure. Study 2 (N = 200) also manipulated deviant status but focused on participants’ subjective evaluations of the organizational structure of their workplace. Findings: Study 1 found that participants reported lower job satisfaction and organizational commitment, and higher turnover intentions when they imagined being confronted with deviant behaviors displayed by a manager (vs. by a subordinate), regardless of the type of organizational structure. Study 2 extended this finding by showing that the indirect effect of organizational structure (vertical vs. horizontal) on turnover intention via job satisfaction and organizational commitment was moderated by deviant status: when the deviant’s status was higher, working in a vertical (vs. horizontal) organization was associated with decreased job satisfaction and commitment, which in turn was associated with a higher level of turnover intentions. Originality/value: The findings broaden our understanding of how individuals respond to deviance at the workplace, by simultaneously considering the effects of organizational structure (vertical vs. horizontal) and deviant status (upward vs. downward directions of deviance). Keywords: organizational structure, status, workplace deviance, job satisfaction, organizational commitment, turnover intentio

    Chromosomal organization of the 18S and 5S rRNAs and histone H3 genes in Scarabaeinae coleopterans: insights into the evolutionary dynamics of multigene families and heterochromatin

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    <p>Abstract</p> <p>Background</p> <p>Scarabaeinae beetles show a high level of macro-chromosomal variability, although the karyotypic organization of heterochromatin and multigene families (rDNAs and histone genes) is poorly understood in this group. To better understand the chromosomal organization and evolution in this group, we analyzed the karyotypes, heterochromatin distribution and chromosomal locations of the rRNAs and histone H3 genes in beetles belonging to eight tribes from the Scarabaeinae subfamily (Coleoptera, Scarabaeidae).</p> <p>Results</p> <p>The number of 18S rRNA gene (a member of the 45S rDNA unit) sites varied from one to 16 and were located on the autosomes, sex chromosomes or both, although two clusters were most common. Comparison of the 45S rDNA cluster number and the diploid numbers revealed a low correlation value. However, a comparison between the number of 45S rDNA sites per genome and the quantity of heterochromatin revealed (i) species presenting heterochromatin restricted to the centromeric/pericentromeric region that contained few rDNA sites and (ii) species with a high quantity of heterochromatin and a higher number of rDNA sites. In contrast to the high variability for heterochromatin and 45S rDNA cluster, the presence of two clusters (one bivalent cluster) co-located on autosomal chromosomes with the 5S rRNA and histone H3 genes was highly conserved.</p> <p>Conclusions</p> <p>Our results indicate that the variability of the 45S rDNA chromosomal clusters is not associated with macro-chromosomal rearrangements but are instead related to the spread of heterochromatin. The data obtained also indicate that both heterochromatin and the 45S rDNA loci could be constrained by similar evolutionary forces regulating spreading in the distinct Scarabaeinae subfamily lineages. For the 5S rRNA and the histone H3 genes, a similar chromosomal organization could be attributed to their association/co-localization in the Scarabaeinae karyotypes. These data provide evidence that different evolutionary forces act at the heterochromatin and the 45S rDNA loci compared to the 5S rRNA and histone H3 genes during the evolution of the Scarabainae karyotypes.</p

    Determinação da atividade de invertase em extratos enzimáticos.

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    bitstream/CNPAT-2010/10231/1/Dc-108.pd

    Crescimento de plantas de mirtileiro sob influência de diferentes doses de nitrogênio.

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    bitstream/item/67357/1/Comunicado-274.pd

    Análise da precipitação e do número de dias de chuva no município de Petrolina - PE.

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    O objetivo desse estudo foi foi analisar a relação entre o número de dias de chuva e a precipitação no município de Petrolina - PE para gerar informações que possam servir de indicativo para uma utilização mais adequada da água da chuva. Os dados foram obtidos na Estação Meteorológica Convencional de Bebedouro no período de 1987 a 2004. As correlações entre os números de dias de chuva e precipitação foram verificadas pelo teste F ao nível de 5%. Os dados médios apresentaram precipitação anual igual a 520 mm ocorrida em 53 dias. Os meses que apresentaram os maiores valores totais de precipitação foram janeiro, fevereiro e março, cujo total pluviométrico foi 299,0 mm distribuídos em apenas 23 dias ao longo dos três meses. Já o trimestre julho, agosto e setembro é o menos chuvoso, com 13,8 mm em 6 dias. Nos anos de precipitação abaixo da média, existiu uma melhor distribuição temporal das chuvas, ao contrário de quando choveu acima da média, que a precipitação foi mais concentrada no tempo. Houve tendêcia significativa de incremento na precipitação e no número de dias com chuva no primeiro trimestre do ano; enquanto que no segundo e no quarto trimestres, essa tendência é inversa, ou seja, de redução tanto da precipitação como do número de dias de chuva, quando se considera o período de 1987 a 2004, em Bebedouro, Petrolina-PE
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