47,060 research outputs found

    [Review of] Paul A. Scanlon, ed. Stories from Central and Southern Africa

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    Any work in the prestigious paperback African Writers Series commands immediate attention and respect. As policy makers and policy breakers wrestle about the South African question -- newly discovering the horrors of an inequality that has existed for more than 300 years -- it is refreshing to look at this collection of twenty-two short narratives. They provide a proper cultural baseline for the current struggle. Like it or not, what lies underneath the political turmoil are cultural values

    [Review of] Mark Naison. Communists in Harlem During the Depression

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    The Communist Party and its relationship to blacks in the United States is a difficult subject to fully research. Necessary critical information must lie in still secret vaults in Washington and in Moscow. Naison\u27s former dissertation is a praise-worthy effort to unravel fact from fantasy as it applied to Black Harlem and the Party

    Still the century of ‘new’ environmental policy instruments? Exploring patterns of innovation and continuity

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    This article re-examines the political interest in and use of ‘new' environmental policy instruments (NEPIs) and other non-regulatory modes of governance. It starts by taking stock of the dynamic debate that has emerged around this topic since the turn of the century. It then contextualizes that debate by examining subsequent challenges to, and transformations in state-led governing and the widely acknowledged rise of 'new governance' more generally. It highlights the mismatch between: (a) the animated discussion of new instruments amongst policy makers and academics; and (b), the less active adoption and performance of them in practice. It makes an overall assessment of the role of instruments - both ‘old' and ‘new' - in the wider debate about governance, and suggests some steps that could be taken by both practitioners and scholars better to understand and possibly even utilise more NEPIs in the future

    RPYS i/o: A web-based tool for the historiography and visualization of citation classics, sleeping beauties, and research fronts

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    Reference Publication Year Spectroscopy (RPYS) and Multi-RPYS provide algorithmic approaches to reconstructing the intellectual histories of scientific fields. With this brief communication, we describe a technical advancement for developing research historiographies by introducing RPYS i/o, an online tool for performing standard RPYS and Multi-RPYS analyses interactively (at http://comins.leydesdorff.net/). The tool enables users to explore seminal works underlying a research field and to plot the influence of these seminal works over time. This suite of visualizations offers the potential to analyze and visualize the myriad of temporal dynamics of scientific influence, such as citation classics, sleeping beauties, and the dynamics of research fronts. We demonstrate the features of the tool by analyzing--as an example--the references in documents published in the journal Philosophy of Science

    Sufficient conditions for uniqueness of the weak value

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    We review and clarify the sufficient conditions for uniquely defining the generalized weak value as the weak limit of a conditioned average using the contextual values formalism introduced in Dressel J, Agarwal S and Jordan A N 2010 Phys. Rev. Lett. 104, 240401. We also respond to criticism of our work in [arXiv:1105.4188v1] concerning a proposed counter-example to the uniqueness of the definition of the generalized weak value. The counter-example does not satisfy our prescription in the case of an underspecified measurement context. We show that when the contextual values formalism is properly applied to this example, a natural interpretation of the measurement emerges and the unique definition in the weak limit holds. We also prove a theorem regarding the uniqueness of the definition under our sufficient conditions for the general case. Finally, a second proposed counter-example in [arXiv:1105.4188v6] is shown not to satisfy the sufficiency conditions for the provided theorem.Comment: 17 pages, final published respons

    Action principle for continuous quantum measurement

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    We present a stochastic path integral formalism for continuous quantum measurement that enables the analysis of rare events using action methods. By doubling the quantum state space to a canonical phase space, we can write the joint probability density function of measurement outcomes and quantum state trajectories as a phase space path integral. Extremizing this action produces the most-likely paths with boundary conditions defined by preselected and postselected states as solutions to a set of ordinary differential equations. As an application, we analyze continuous qubit measurement in detail and examine the structure of a quantum jump in the Zeno measurement regime.Comment: Published version. 8 pages, 3 figures, movies available at http://youtu.be/OQ3PwkSKEUw and http://youtu.be/sTlV2amQtj

    Stochastic dynamics of a Josephson junction threshold detector

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    We generalize the stochastic path integral formalism by considering Hamiltonian dynamics in the presence of general Markovian noise. Kramers' solution of the activation rate for escape over a barrier is generalized for non-Gaussian driving noise in both the overdamped and underdamped limit. We apply our general results to a Josephson junction detector measuring the electron counting statistics of a mesoscopic conductor. Activation rate dependence on the third current cumulant includes an additional term originating from the back-action of the measurement circuit.Comment: 5 pages, 2 figures, discussion of experiment added, typos correcte
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