15,092 research outputs found

    Full Length Research Paper Lack of correlation between H2O2 production and in vitro anti-staphyloccocal activity of vaginal Lactobacillus spp.

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    Lactobacilli are considered to play important roles in human health as they are known to secrete inhibitory substances to prevent infection by pathogenic organisms. Previously we have isolated 77 strains of Lactobacillus spp. from human vaginas. In this study, using the plate diffusion method, strains showing in vitro antagonistic activity against pathogenic Staphylococcus aureus were screened. Because Lactobacillus spp. are known to produce hydrogen peroxide (H2O2) as an antimicrobialsubstance, we attempted to determine if there is a consistent link between in vitro anti-staphylococcal activity and H2O2 production by Lactobacillus spp. A simple quantitative analysis of H2O2 produced by Lactobacillus spp. was performed by a modified spectrophotometric method. A statistically significant correlation was not found between in vitro anti-staphylococcal activity and H2O2 production

    Gravitational energy in a small region for the modified Einstein and Landau-Lifshitz pseudotensors

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    The purpose of the classical Einstein and Landau-Lifshitz pseudotensors is for determining the gravitational energy. Neither of them can guarantee a positive energy in holonomic frames. In the small sphere approximation, it has been required that the quasilocal expression for the gravitational energy-momentum density should be proportional to the Bel-Robinson tensor BαβμνB_{\alpha\beta\mu\nu}. However, we propose a new tensor VαβμνV_{\alpha\beta\mu\nu} which is the sum of certain tensors SαβμνS_{\alpha\beta\mu\nu} and KαβμνK_{\alpha\beta\mu\nu}, it has certain properties so that it gives the same gravitational "energy-momentum" content as BαβμνB_{\alpha\beta\mu\nu} does. Moreover, we show that a modified Einstein pseudotensor turns out to be one of the Chen-Nester quasilocal expressions, while the modified Landau-Lifshitz pseudotensor becomes the Papapetrou pseudotensor; these two modified pseudotensors have positive gravitational energy in a small region.Comment:

    Reasoning with comparative moral judgements: an argument for Moral Bayesianism

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    The paper discusses the notion of reasoning with comparative moral judgements (i.e judgements of the form “act a is morally superior to act b”) from the point of view of several meta-ethical positions. Using a simple formal result, it is argued that only a version of moral cognitivism that is committed to the claim that moral beliefs come in degrees can give a normatively plausible account of such reasoning. Some implications of accepting such a version of moral cognitivism are discussed

    Molecular transistor coupled to phonons and Luttinger-liquid leads

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    We study the effects of electron-phonon interactions on the transport properties of a molecular quantum dot coupled to two Luttinger-liquid leads. In particular, we investigate the effects on the steady state current and DC noise characteristics. We consider both equilibrated and unequilibrated on-dot phonons. The density matrix formalism is applied in the high temperature approximation and the resulting semi-classical rate equation is numerically solved for various strengths of electron-electron interactions in the leads and electron-phonon coupling. The current and the noise are in general smeared out and suppressed due to intralead electron interaction. On the other hand, the Fano factor, which measures the noise normalized by the current, is more enhanced as the intralead interaction becomes stronger. As the electron-phonon coupling becomes greater than order one, the Fano factor exhibits super-Poissonian behaviour.Comment: 11 pages, 11 figure

    Neural Network Model for Apparent Deterministic Chaos in Spontaneously Bursting Hippocampal Slices

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    A neural network model that exhibits stochastic population bursting is studied by simulation. First return maps of inter-burst intervals exhibit recurrent unstable periodic orbit (UPO)-like trajectories similar to those found in experiments on hippocampal slices. Applications of various control methods and surrogate analysis for UPO-detection also yield results similar to those of experiments. Our results question the interpretation of the experimental data as evidence for deterministic chaos and suggest caution in the use of UPO-based methods for detecting determinism in time-series data.Comment: 4 pages, 5 .eps figures (included), requires psfrag.sty (included

    Nonequilibrium quantum criticality in open electronic systems

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    A theory is presented of quantum criticality in open (coupled to reservoirs) itinerant electron magnets, with nonequilibrium drive provided by current flow across the system. Both departures from equilibrium at conventional (equilibrium) quantum critical points and the physics of phase transitions induced by the nonequilibrium drive are treated. Nonequilibrium-induced phase transitions are found to have the same leading critical behavior as conventional thermal phase transitions.Comment: 5 pages, 1 figur

    Teachers' beliefs about knowledge and learning: A Singapore perspective

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    The purpose of this study is to explore the complex nature of Singapore teachers' beliefs about knowledge and learning and how these beliefs influence pedagogical practices in their classes. This paper presents findings from a large-scale survey study with 1806 teachers in Singapore. Data revealed that while teachers' beliefs about pedagogies, knowledge and learning were largely consistent, they also believed and practiced both teacher-centered and learner-centered pedagogies and assessment methods
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