15,820 research outputs found

    The Colonial Dynamic: The Xhosa Cattle Killing and the American Indian Ghost Dance

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    In 1856, a fourteen year old girl named Nongqawuse (non-see) had a vision on the banks of the Gxarha River in southern Africa. Entranced, she saw dearly departed ancestors, their cattle hiding in the rushes, and she heard other cattle underground waiting to come forth. She was told that if her people would but kill all their cattle, their ancestors would arise from the dead, the cattle lowing in the subterranean passages would come forth, and all the whites would be swept into the sea. Nongqawuse’s prophecy provoked the colonially embittered Xhosa (cōe-săh) people to rise up and kill their cattle. As the movement drew to a close, around 400,000 cattle had been slaughtered and an estimated 80,000 Xhosa died of starvation. Those that remained were reduced to working as laborers throughout the Cape Colony after being pushed off some 600,000 acres of their ancestral lands

    Coset construction of a D-brane gauge field

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    D-branes have a world-volume U(1) gauge field A whose field strength F = dA gives rise to a Born-Infeld term in the D-brane action. Supersymmetry and kappa symmetry transformations of A are traditionally inferred by the requirement that the Born-Infeld term is consistent with both supersymmetry and kappa symmetry of the D-brane action. In this paper, we show that integrability of the assigned supersymmetry transformations leads to a extension of the standard supersymmetry algebra that includes a fermionic central charge. We construct a superspace one-form on an enlarged superspace related by a coset construction to this centrally extended algebra whose supersymmetry and kappa symmetry transformations are derived, rather than inferred. It is shown that under pullback, these transformations are of the form expected for the D-brane U(1) gauge field. We relate these results to manifestly supersymmetric approaches to construction of D-brane actions.Comment: 15 pages; new section and references adde

    Automated post-fault diagnosis of power system disturbances

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    In order to automate the analysis of SCADA and digital fault recorder (DFR) data for a transmission network operator in the UK, the authors have developed an industrial strength multi-agent system entitled protection engineering diagnostic agents (PEDA). The PEDA system integrates a number of legacy intelligent systems for analyzing power system data as autonomous intelligent agents. The integration achieved through multi-agent systems technology enhances the diagnostic support offered to engineers by focusing the analysis on the most pertinent DFR data based on the results of the analysis of SCADA. Since November 2004 the PEDA system has been operating online at a UK utility. In this paper the authors focus on the underlying intelligent system techniques, i.e. rule-based expert systems, model-based reasoning and state-of-the-art multi-agent system technology, that PEDA employs and the lessons learnt through its deployment and online use

    Using evidence combination for transformer defect diagnosis

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    This paper describes a number of methods of evidence combination, and their applicability to the domain of transformer defect diagnosis. It explains how evidence combination fits into an on-line and implemented agent-based condition monitoring system, and the benefits of giving selected agents reflective abilities. Reflection has not previously been deployed in an industrial setting, and theoretical work has been in domains other than power engineering. This paper presents the results of implementing five different methods of evidence combination, showing that reflective techniques give greater accuracy than non-reflective

    Advances in emerging therapies 2009

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