3,510 research outputs found

    Physical aspects of naked singularity explosion - How does a naked singularity explode? --

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    The behaviors of quantum stress tensor for the scalar field on the classical background of spherical dust collapse is studied. In the previous works diverging flux of quantum radiation was predicted. We use the exact expressions in a 2D model formulated by Barve et al. Our present results show that the back reaction does not become important during the semiclassical phase. The appearance of the naked singularity would not be affected by this quantum field radiation. To predict whether the naked singularity explosion occurs or not we need the theory of quantum gravity. We depict the generation of the diverging flux inside the collapsing star. The quantum energy is gathered around the center positively. This would be converted to the diverging flux along the Cauchy horizon. The ingoing negative flux crosses the Cauchy horizon. The intensity of it is divergent only at the central naked singularity. This diverging negative ingoing flux is balanced with the outgoing positive diverging flux which propagates along the Cauchy horizon. After the replacement of the naked singularity to the practical high density region the instantaneous diverging radiation would change to more milder one with finite duration.Comment: 18 pages, 16 figure

    General Connectivity Distribution Functions for Growing Networks with Preferential Attachment of Fractional Power

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    We study the general connectivity distribution functions for growing networks with preferential attachment of fractional power, ╬áiÔłŁk╬▒\Pi_{i} \propto k^{\alpha}, using the Simon's method. We first show that the heart of the previously known methods of the rate equations for the connectivity distribution functions is nothing but the Simon's method for word problem. Secondly, we show that the case of fractional ╬▒\alpha the ZZ-transformation of the rate equation provides a fractional differential equation of new type, which coincides with that for PA with linear power, when ╬▒=1\alpha = 1. We show that to solve such a fractional differential equation we need define a transidental function ╬ą(a,s,c;z)\Upsilon (a,s,c;z) that we call {\it upsilon function}. Most of all previously known results are obtained consistently in the frame work of a unified theory.Comment: 10 page

    New approaches for estimating risk from exposure to diethylstilbestrol.

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    A subgroup from a National Institute of Environmental Health Sciences, workshop concerned with characterizing the effects of endocrine disruptors on human health at environmental exposure levels considered the question, If diethylstilbestrol (DES) were introduced into the market for human use today and likely to result in low-dose exposure of the human fetus, what would be required to assess risk? On the basis of an analysis of the quality of data on human DES exposure, the critical times and doses for inducing genital tract malformations and cancer must be determined. This would be facilitated through analysis of the ontogeny of estrogen receptor expression in the developing human genital tract. Models of low-dose estrogenic effects will have to be developed for human and rodent genital tract development. Mouse models offer many advantages over other potential animal models because of the wealth of the earlier literature, the availability of sensitive end points, the availability of mutant lines, and the possibility of generating genetically engineered model systems. Through multidisciplinary approaches, it should be possible to elucidate the cellular and molecular mechanisms of endocrine disruption elicited by estrogens during development and facilitate an assessment of risk to humans

    Potential flow theory and operation guide for the panel code PMARC

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    The theoretical basis for PMARC, a low-order potential-flow panel code for modeling complex three-dimensional geometries, is outlined. Several of the advanced features currently included in the code, such as internal flow modeling, a simple jet model, and a time-stepping wake model, are discussed in some detail. The code is written using adjustable size arrays so that it can be easily redimensioned for the size problem being solved and the computer hardware being used. An overview of the program input is presented, with a detailed description of the input available in the appendices. Finally, PMARC results for a generic wing/body configuration are compared with experimental data to demonstrate the accuracy of the code. The input file for this test case is given in the appendices

    MNE R&D internationalization in developing Asia

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    In line with the recent shift of R&D internationalization towards developing Asia, this Perspective paper reviews, contextualises, and evaluates the evolving patterns of creation, transfer, and assimilation of knowledge in multinational enterprises (MNEs). A typology is proposed consisting of four stylized nodes: West (industrialized mature economies), East One (emerging industrializing economies of developing Asia), East Two (Asian economies at an earlier stage of industrialization), and East Three (Asian economies with limited visible signs of industrialization). Within these nodes, this paper applies an institution-based view to discuss their diverse national innovation environment (with particular attention paid to governments, indigenous firms, and institutional conditions), and the network perspective to propose an intra-regional knowledge hierarchy, reflecting dynamic knowledge links

    The thermodynamic limit for fractional exclusion statistics

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    I discuss Haldane's concept of generalised exclusion statistics (Phys. Rev. Lett. {\bf 67}, 937, 1991) and I show that it leads to inconsistencies in the calculation of the particle distribution that maximizes the partition function. These inconsistencies appear when mutual exclusion statistics is manifested between different subspecies of particles in the system. In order to eliminate these inconsistencies, I introduce new mutual exclusion statistics parameters, which are proportional to the dimension of the Hilbert sub-space on which they act. These new definitions lead to properly defined particle distributions and thermodynamic properties. In another paper (arXiv:0710.0728) I show that fractional exclusion statistics manifested in general systems with interaction have these, physically consistent, statistics parameters.Comment: 8 page

    The structure of non-spacelike geodesics in dust collapse

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    We study here the behaviour of non-spacelike geodesics in dust collapse models in order to understand the casual structure of the spacetime. The geodesic families coming out, when the singularity is naked, corresponding to different initial data are worked out and analyzed. We also bring out the similarity of the limiting behaviour for different types of geodesics in the limit of approach to the singularity.Comment: 23 pages, 6 figures, to appear in PR
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