117,429 research outputs found

    The response of the moderate wing of the Civil Rights Movement to the war in Vietnam

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    This article explores the response of the moderate wing of the civil rights movement to the war in Vietnam. The moderates, made up of the National Association for the Advancement of Colored People (NAACP), the National Urban League, and leaders such as Bayard Rustin and A. Philip Randolph, were initially opposed to the civil rights movement taking a stand against the war. This reluctance was the result of a number of factors, including anti-communism and their own closeness with the administration of President Lyndon Johnson. Crucially, it also resulted from their own experiences of the black freedom struggle itself. The article also documents and analyses the growing anti-war dissent amongst the moderates, culminating in the decision of both the NAACP and the Urban League to adopt an anti-war stance at the end of the 1960s. Despite this, they remained unenthusiastic about participating in peace movement activities, and the reasons for this are explained. Finally, the article suggests that the war was important in exposing existing divisions within the civil rights movement, as well as in generating new ones

    The principle of equivalence and projective structure in space-times

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    This paper discusses the extent to which one can determine the space-time metric from a knowledge of a certain subset of the (unparametrised) geodesics of its Levi-Civita connection, that is, from the experimental evidence of the equivalence principle. It is shown that, if the space-time concerned is known to be vacuum, then the Levi-Civita connection is uniquely determined and its associated metric is uniquely determined up to a choice of units of measurement, by the specification of these geodesics. It is further demonstrated that if two space-times share the same unparametrised geodesics and only one is assumed vacuum then their Levi-Civita connections are again equal (and so the other metric is also a vacuum metric) and the first result above is recovered.Comment: 23 pages, submitted to Classical and Quantum Gravit

    On the Theory of Killing Orbits in Space-Time

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    This paper gives a theoretical discussion of the orbits and isotropies which arise in a space-time which admits a Lie algebra of Killing vector fields. The submanifold structure of the orbits is explored together with their induced Killing vector structure. A general decomposition of a space-time in terms of the nature and dimension of its orbits is given and the concept of stability and instability for orbits introduced. A general relation is shown linking the dimensions of the Killing algebra, the orbits and the isotropies. The well-behaved nature of "stable" orbits and the possible miss-behaviour of the "unstable" ones is pointed out and, in particular, the fact that independent Killing vector fields in space-time may not induce independent such vector fields on unstable orbits. Several examples are presented to exhibit these features. Finally, an appendix is given which revisits and attempts to clarify the well-known theorem of Fubini on the dimension of Killing orbits.Comment: Latex, 19 pages, no figur

    Resource Letter BEC-1: Bose-Einstein Condensates in Trapped Dilute Gases

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    This Resource Letter provides a guide to the literature on Bose-Einstein condensation in trapped dilute gases. Journal articles and books are cited for the following topics: history, technological advances, condensates as quantum fluids, effects of interatomic interactions, condensates as matter waves, condensate optics, multiple condensates, lower dimensions, spectroscopy and precision measurement, entanglement, and cosmology.Comment: 12 pages, 0 figure

    Self-similar static solutions admitting a two-space of constant curvature

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    A recent result by Haggag and Hajj-Boutros is reviewed within the framework of self-similar space-times, extending, in some sense, their results and presenting a family of metrics consisting of all the static spherically symmetric perfect fluid solutions admitting a homothety.Comment: 6 page

    A scanning polarimeter

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    Optical system of scanning polarimeter with improved photoelectric resolutio
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