25,701 research outputs found
How the Ji’kmaqn Came to Spiro: Possible Additions to the Inventory of Sound-Making Instruments Depicted in the Spiro Engravings
While doing research on turtle shell rattles the author stumbled onto a photograph of a rare and unusual idiophone whose exact likeness appears twice in one of the engraved shell images from Spiro. This paper describes the instrument and the Spiro image and discusses how an instrument currently found only in the Maritime Provinces of Canada may have come to be portrayed on a marine shell cup found at Spiro
English Regions Devolution Monitoring Report: January 2009: new regional structures for changed times
Descriptions of reversed yielding in bending
Existence of Bauschinger effect in bending-unbending of copper beams has been shown from experiment. In modelling of the Bauschinger effect, it is shown that a significant second plastic penetration can occur with the release of the moment required for an elasticplastic bending of a beam. The theory is given for both linear and parabolic hardening material models. The elastic and plastic strains are developed from each hardening model to express the beam curvature of the unstressed neutral axis. Conditions are expressed, using the normalized stress—strain response of a rectangular beam section, for which the release is purely elastic and elastic—plastic. Under the latter the depth to which a second zone of plasticity penetrates is given. Two stress distributions: one for applying the moment and the other for its release, are sufficient to derive the residual stress. Residuals found for parabolic hardening are believed to be more realistic than those from simpler linear or perfectly plastic models, particularly, where a second penetration is evident
Reprocessing of radiation by multi-phase gas in Low Luminosity Accretion Flows
We discuss the role that magnetic fields in low luminosity accretion flows
can play in creating and maintaining a multi-phase medium, and show that small
magnetically-confined clouds or filaments of dense cold gas can dramatically
reprocess the `primary' radiation from tori. In particular, radio emission
would be suppressed by free-free absorption, and an extra (weak) component
would appear at optical wavelengths. This is expected to be a common process in
various environments in the central regions of Active Galaxies, such as broad
line regions, accretion disk coronae and jets.Comment: submitted to MNRAS; 4 pages, 1 figure (MNRAS LaTex style
Chebyshev semi-iteration in Preconditioning
It is widely believed that Krylov subspace iterative methods are better than Chebyshev semi-iterative methods. When the solution of a linear system with a symmetric and positive definite coefficient matrix is required then the Conjugate Gradient method will compute the optimal approximate solution from the appropriate Krylov subspace, that is, it will implicitly compute the optimal polynomial. Hence a semi-iterative method, which requires eigenvalue bounds and computes an explicit polynomial, must, for just a little less computational work, give an inferior result. In this manuscript we identify a specific situation in the context of preconditioning when the Chebyshev semi-iterative method is the method of choice since it has properties which make it superior to the Conjugate Gradient method
Reverse Transplant Tourism
In this article, we propose a novel form of kidney swap, which we label “Reverse Transplant Tourism.” This proposal has the potential to increase the number of successful transplants in the US at a time of great need, while reducing costs. It also will provide benefits to impoverished international patients with willing, compatible donors who otherwise would have no access to transplantation. Instead of non-US kidney donors being offered money through a black market middleman in exchange for one of their kidneys, Reverse Transplant Tourism would provide a legal and ethical exchange of living donor kidneys through kidney-paired donation. In this way, the donors will not receive money for their kidneys, but rather will receive a transplant for someone they love, while also helping a US pair who would otherwise be unable to transplant due to biological incompatibility
Religious actors, civil society, and the development agenda: The dynamics of inclusion and exclusion
This article uses the World Bank\u27s engagement with religious actors to analyse their differentiated role in setting the development agenda raising three key issues. First, engagements between international financial institutions (IFIs) and religious actors are formalised thus excluding many of the actors embedded within communities in the South. Secondly, the varied politics of religious actors in development are rarely articulated and a single position is often presented. Thirdly, the potential for development alternatives from religious actors excluded from these engagements is overlooked, due in part to misrecognition of the mutually constitutive relationship between secular and sacral elements in local contexts
Limits from rapid TeV variability of Mrk 421
The extreme variability event in the TeV emission of Mrk 421, recently
reported by the Whipple team, imposes the tightest limits on the typical size
of the TeV emitting regions in Active Galactic Nuclei (AGN). We examine the
consequences that this imposes on the bulk Lorentz factor of the emitting
plasma and on the radiation fields present in the central region of this Active
Nucleus. No strong evidence is found for extreme Lorentz factors. However,
energetics arguments suggest that any accretion in Mrk 421 has to take place at
small rates, compatible with an advection-dominated regime.Comment: 5 pages (Latex MNRAS style), revised version, submitted to MNRA
The Optimal Rate of Decline of an Inefficient Industry
This paper considers the problem of the optimal time path of contraction of an industry which has been hit by foreign competition, and shows that in general, along the optimal path, a production subsidy is warranted. The optimal subsidy trades off the benefit of unemployment in speeding up the approach to the new long-run equilibrium against the cost of lost output in the ‘inefficient’ industry. The dynamic shadow price of labour in this industry is also derived and shown to be always positive, though below the industry wage rate
Dense, thin clouds and reprocessed radiation in the central regions of Active Galactic Nuclei
The primary radiation generated in the central continuum-forming region of
Active Galactic Nuclei can be reprocessed by very dense, small-scale clouds
that are optically-thin to Thomson scattering. In spite of the extreme
conditions expected to prevail in this innermost, central environment, the
radiative clouds can survive and maintain cool temperatures relative to the
ambient emitting region by means of magnetic confinement. Motivated by these
ideas, we present a detailed quantitative study of such clouds, explicitly
describing the physical properties they can attain under thermal and radiative
equilibrium conditions. We also discuss the thermal stability of the gas in
comparison to that of other reprocessing material thought to reside at larger
distances from the central source. We construct a model to predict the emergent
spectra from a source region containing dense clouds which absorb and reemit
the primary radiation generated therein. Our predicted spectra show the
following two important results: (i) the reprocessed flux emitted at optical/UV
energies is insufficient to account for the blue bump component in the observed
spectra; and (ii) the amount of line radiation that is emitted is at least
comparable to (and in many cases dominates) the continuum radiation. The lines
are extremely broad and tend to accumulate in the extreme ultraviolet, where
they form a peak much more prominent than that which is observed in the
optical/UV. This result is supported by current observations, which indicate
that the spectral energy distribution of radio-quiet AGN may indeed reach a
maximum in the EUV band.Comment: 14 pages, 5 figures, latex, uses epsf and rotate, accepted for
publication in M
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