44,035 research outputs found

    Parasites, pawns and partners: disability research and the role of non-disabled researchers

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    Important methodological questions are raised by the act of researching disablement. Disability research has attracted much methodological criticism from disabled people who argue that it has taken place within an oppressive theoretical paradigm and within an oppressive set of social relations. These issues are of heightened significance for non-disabled researchers and bear many similarities to those faced by researchers investigating barriers to the social inclusion of women, Black and ‘Third World’ peoples. Such challenges have led to the development of an ‘emancipatory’ research paradigm. Six principles of emancipatory research are identified and the authors’ own research projects are critically examined within this framework. A number of contradictions are identified and an attempt made to balance the twin requirements of political action and academic rigour

    THE IMPACT OF "BIG-BOX" BUILDING MATERIALS STORES ON HOST TOWNS AND SURROUNDING COUNTIES IN A MIDWESTERN STATE

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    This paper analyzes 11 regions in a midwestern state where big-box building materials stores have opened. The zero-sum-game theory is verified; the sales gains in the host counties equaled the losses in the surrounding counties. The results are important to existing merchants and local officials in setting strategies and policies.Community/Rural/Urban Development,

    Energy in one dimensional linear waves in a string

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    We consider the energy density and energy transfer in small amplitude, one-dimensional waves on a string, and find that the common expressions used in textbooks for the introductory physics with calculus course give wrong results for some cases, including standing waves. We discuss the origin of the problem, and how it can be corrected in a way appropriate for the introductory calculus based physics course.Comment: 5 page

    Infinite Symmetry in the Fractional Quantum Hall Effect

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    We have generalized recent results of Cappelli, Trugenberger and Zemba on the integer quantum Hall effect constructing explicitly a W1+{\cal W}_{1+\infty} for the fractional quantum Hall effect such that the negative modes annihilate the Laughlin wave functions. This generalization has a nice interpretation in Jain's composite fermion theory. Furthermore, for these models we have calculated the wave functions of the edge excitations viewing them as area preserving deformations of an incompressible quantum droplet, and have shown that the W1+{\cal W}_{1+\infty} is the underlying symmetry of the edge excitations in the fractional quantum Hall effect. Finally, we have applied this method to more general wave functions.Comment: 15pp. LaTeX, BONN-HE-93-2

    Analysis of unbounded operators and random motion

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    We study infinite weighted graphs with view to \textquotedblleft limits at infinity,\textquotedblright or boundaries at infinity. Examples of such weighted graphs arise in infinite (in practice, that means \textquotedblleft very\textquotedblright large) networks of resistors, or in statistical mechanics models for classical or quantum systems. But more generally our analysis includes reproducing kernel Hilbert spaces and associated operators on them. If XX is some infinite set of vertices or nodes, in applications the essential ingredient going into the definition is a reproducing kernel Hilbert space; it measures the differences of functions on XX evaluated on pairs of points in XX. And the Hilbert norm-squared in H(X)\mathcal{H}(X) will represent a suitable measure of energy. Associated unbounded operators will define a notion or dissipation, it can be a graph Laplacian, or a more abstract unbounded Hermitian operator defined from the reproducing kernel Hilbert space under study. We prove that there are two closed subspaces in reproducing kernel Hilbert space H(X)\mathcal{H}(X) which measure quantitative notions of limits at infinity in XX, one generalizes finite-energy harmonic functions in H(X)\mathcal{H}(X), and the other a deficiency index of a natural operator in H(X)\mathcal{H}(X) associated directly with the diffusion. We establish these results in the abstract, and we offer examples and applications. Our results are related to, but different from, potential theoretic notions of \textquotedblleft boundaries\textquotedblright in more standard random walk models. Comparisons are made.Comment: 38 pages, 4 tables, 3 figure

    AN ANALYSIS OF THE TRANSFER OF FUNDS FROM WEAK RETAIL COUNTIES TO STRONG RETAIL COUNTIES IN IOWA VIA LOCAL OPTION SALES TAXES

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    This study analyzes the transfer of tax dollars from "retail poor" to "retail rich" counties via local option sales taxes in Iowa. These taxes may potentially transfer more than one billion dollars from rural to urban counties over the next ten years. The implications for economic development policy are discussed.Public Economics,

    Energy Anomaly and Polarizability of Carbon Nanotubes

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    The energy of electron Fermi sea perturbed by external potential, represented as energy anomaly which accounts for the contribution of the deep-lying states, is analyzed for massive d = 1+1 Dirac fermions on a circle. The anomaly is a universal function of the applied field, and is related to known field-theoretic anomalies. We express transverse polarizability of Carbon nanotubes via the anomaly, in a way which exhibits the universality and scale-invariance of the response dominated by pi-electrons and qualitatively different from that of dielectric and conducting shells. Electron band transformation in a strong-field effect regime is predicted.Comment: 4 pg

    On the extra phase correction to the semiclassical spin coherent-state propagator

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    The problem of an origin of the Solary-Kochetov extra-phase contribution to the naive semiclassical form of a generalized phase-space propagator is addressed with the special reference to the su(2) spin case which is the most important in applications. While the extra-phase correction to a flat phase-space propagator can straightforwardly be shown to appear as a difference between the principal and the Weyl symbols of a Hamiltonian in the next-to-leading order expansion in the semiclassical parameter, the same statement for the semiclassical spin coherent-state propagator holds provided the Holstein-Primakoff representation of the su(2) algebra generators is employed.Comment: 19 pages, no figures; a more general treatment is presented, some references are added, title is slightly changed; submitted to JM

    Excitation of the CO fourth positive band system by electron impact on carbon monoxide and carbon dioxide

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    Excitation of carbon monoxide fourth positive band system by electron impact on carbon monoxide and carbon dioxid

    The mixing of interplanetary magnetic field lines: A significant transport effect in studies of the energy spectra of impulsive flares

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    Using instrumentation on board the ACE spacecraft we describe short-time scale (~3 hour) variations observed in the arrival profiles of ~20 keV nucleon^(–1) to ~2 MeV nucleon^(–1) ions from impulsive solar flares. These variations occurred simultaneously across all energies and were generally not in coincidence with any local magnetic field or plasma signature. These features appear to be caused by the convection of magnetic flux tubes past the observer that are alternately filled and devoid of flare ions even though they had a common flare source at the Sun. In these particle events we therefore have a means to observe and measure the mixing of the interplanetary magnetic field due to random walk. In a survey of 25 impulsive flares observed at ACE between 1997 November and 1999 July these features had an average time scale of 3.2 hours, corresponding to a length of ~0.03 AU. The changing magnetic connection to the flare site sometimes lead to an incomplete observation of a flare at 1 AU; thus the field-line mixing is an important effect in studies of impulsive flare energy spectra
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