1,485 research outputs found

    Quantum Structure of Space Near a Black Hole Horizon

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    We describe a midi-superspace quantization scheme for generic single horizon black holes in which only the spatial diffeomorphisms are fixed. The remaining Hamiltonian constraint yields an infinite set of decoupled eigenvalue equations: one at each spatial point. The corresponding operator at each point is the product of the outgoing and ingoing null convergences, and describes the scale invariant quantum mechanics of a particle moving in an attractive 1/X21/X^2 potential. The variable XX that is analoguous to particle position is the square root of the conformal mode of the metric. We quantize the theory via Bohr quantization, which by construction turns the Hamiltonian constraint eigenvalue equation into a finite difference equation. The resulting spectrum gives rise to a discrete spatial topology exterior to the horizon. The spectrum approaches the continuum in the asymptotic region.Comment: References added and typos corrected. 21 pages, 1 figur

    Anomalous electron trapping by localized magnetic fields

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    We consider an electron with an anomalous magnetic moment g>2 confined to a plane and interacting with a nonzero magnetic field B perpendicular to the plane. We show that if B has compact support and the magnetic flux in the natural units is F\ge 0, the corresponding Pauli Hamiltonian has at least 1+[F] bound states, without making any assumptions about the field profile. Furthermore, in the zero-flux case there is a pair of bound states with opposite spin orientations. Using a Birman-Schwinger technique, we extend the last claim to a weak rotationally symmetric field with B(r) = O(r^{-2-\delta}) correcting thus a recent result. Finally, we show that under mild regularity assumptions the existence can be proved for non-symmetric fields with tails as well.Comment: A LaTeX file, 12 pages; to appear in J. Phys. A: Math. Ge

    On Lie-algebraic solutions of the type IIB matrix model

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    A systematic search for Lie algebra solutions of the type IIB matrix model is performed. Our survey is based on the classification of all Lie algebras for dimensions up to five and of all nilpotent Lie algebras of dimension six. It is shown that Lie-type solutions of the equations of motion of the type IIB matrix model exist and they correspond to certain nilpotent and solvable Lie algebras. Their representation in terms of Hermitian matrices is discussed in detail. These algebras give rise to certain non-commutative spaces for which the corresponding star-products are provided. Finally the issue of constructing quantized compact nilmanifolds and solvmanifolds based on the above algebras is addressed.Comment: 22 page

    Alterações sensoriais do doce de umbu maduro durante o armazenamento.

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    O umbuzeiro (Spondias tuberosa Arr. Câmara) é uma planta de grande importância econômica para a região semi-árida nordestina, devido a comercialização de frutos in natura e derivados, como doces em massa. Este trabalho teve como objetivo observar as alterações sensoriais ocorridas durante a vida de prateleira de quatro formulações diferentes a 30ºC em relação ao padrão, durante 120 dias. Resultados mostraram que durante o armazenamento houve um aumento na firmeza e na cor natural da fruta, com tendência para um marrom mais escuro e uma leve perda do sabor característico e aroma. Na formulação com 0,5% de amido e 5% de xarope de glicose ocorreu perda moderada do brilho

    Therapeutic and Metagenomic Potential of the Biomolecular Therapies against Periodontitis and the Oral Microbiome: Current Evidence and Future Perspectives

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    The principles of periodontal therapy are based on the control of microbial pathogens and host factors that contribute to biofilm dysbiosis, with the aim of modulating the progression of periodontitis and periodontal tissue destruction. It is currently known how differently each individual responds to periodontal treatment, depending on both the bacterial subtypes that make up the dysbiotic biofilm and interindividual variations in the host inflammatory response. This has allowed the current variety of approaches for the management of periodontitis to be updated by defining the goals of target strategies, which consist of reducing the periodontopathogenic microbial flora and/or modulating the host-mediated response. Therefore, this review aims to update the current variety of approaches for the management of periodontitis based on recent target therapies. Recently, encouraging results have been obtained from several studies exploring the effects of some targeted therapies in the medium- and long-term. Among the most promising target therapies analyzed and explored in this review include: cell-based periodontal regeneration, mediators against bone resorption, emdogain (EMD), platelet-rich plasma, and growth factors. The reviewed evidence supports the hypothesis that the therapeutic combination of epigenetic modifications of periodontal tissues, interacting with the dysbiotic biofilm, is a key step in significantly reducing the development and progression of disease in periodontal patients and improving the therapeutic response of periodontal patients. However, although studies indicate promising results, these need to be further expanded and studied to truly realize the benefits that targeted therapies could bring in the treatment of periodontitis

    Microbiological and colour changes in umbu (Spondias tuberosa Arr. Cam.) in the mature green stage, during storage under accelerated conditions.

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    The objective ofthis study was to study the microbiological and colour changes in pasteurized umbu pulp during 120 days of storage at 40°C.Resumo 657

    Características de doce em massa de umbu verde e maduro e aceitação pelos consumidores

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    O objetivo deste trabalho foi avaliar formulações de doces, em massa de umbu verde e maduro, quanto às características físico-químicas e físicas, e quanto à aceitação pelos consumidores residentes no Rio de Janeiro. Quatro formulações de doces foram processadas para polpa de umbu verde: F1, 0,3% de goma xantana; F2, 5% de xarope de glicose e 0,3% de goma xantana; F3, 0,5% de amido modificado; F4, 5% de xarope de glicose e 0,5% de amido modificado; e quatro formulações para polpa de umbu maduro: F1, apenas correção de pH; F2, 0,5% de pectina; F3, 0,3% de goma xantana; F4, 5% de xarope de glicose e 0,5% de amido modificado. Foram avaliadas as seguintes características físico-químicas e físicas: sólidos solúveis, acidez titulável, pH, açúcares redutores e não redutores, atividade de água, cor, firmeza e adesividade. Cinqüenta e seis consumidores avaliaram as formulações, por meio de escala hedônica estruturada de nove pontos. As formulações F2 apresentaram maior firmeza. Os consumidores atribuíram notas superiores a seis na escala utilizada, para todas as formulações, o que indica aceitação dos produtos

    Avaliação e seleção de porta-enxertos de cajueiro anão precoce.

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    O cultivo de cajueiro anao precoce ... Atualmente, encontram-se disponiveis para cultivo seis clones de cajueiro anao precoce, dos quais somente quatro sao explorados comercialmente para copa ...bitstream/CNPAT-2010/5382/1/Pa-075.pd
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