155,847 research outputs found

    A wave-function Monte Carlo method for simulating conditional master equations

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    Wave-function Monte Carlo methods are an important tool for simulating quantum systems, but the standard method cannot be used to simulate decoherence in continuously measured systems. Here we present a new Monte Carlo method for such systems. This was used to perform the simulations of a continuously measured nano-resonator in [Phys. Rev. Lett. 102, 057208 (2009)].Comment: 4 pages, revtex 4, 1 eps figure. v2: correction to Eqs (3),(9), and (11); v3 added further informatio

    An Institution of Modal Logics for Coalgebras

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    This paper presents a modular framework for the specification of certain inductively-defined coalgebraic types. Modal logics for coalgebras of polynomial endofunctors on the category of sets have been studied in [M. Rößiger, Coalgebras and modal logic, in: H. Reichel (Ed.), Coalgebraic Methods in Computer Science, Electronic Notes in Theoretical Computer Science, vol. 33, Elsevier Science, 2000, pp. 299–320; B. Jacobs, Many-sorted coalgebraic modal logic: a model-theoretic study, Theoretical Informatics and Applications 35(1) (2001) 31–59]. These logics are here generalised to endofunctors on categories of sorted sets, in order to allow collections of inter-related types to be specified simultaneously. The inductive nature of the coalgebraic types considered is then used to formalise semantic relationships between different types, and to define translations between the associated logics. The resulting logical framework is shown to be an institution, whose specifications and specification morphisms admit final and respectively cofree models

    ‘The party’s over’: critical junctures, crises and the politics of housing policy

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    The key argument set out in this article is that historical and comparative forms of investigation are necessary if we are to better understand the ambitions and scope of contemporary housing interventions. To demonstrate the veracity of our claim, we have set out an analysis of the UK housing polices enacted in the mid-1970s as a basis for comparison with those pursued 40 years later. The article begins with a critical summary of some of the methodological approaches adopted by researchers used to interpret housing policy. In the main section, we present our critical analysis of housing policy reforms (implemented by the Labour government between 1974 and 1979) noting both their achievements and limitations. In the concluding section, we use our interpretation of this period as a basis to judge contemporary housing policy and reflect on the methodological issues that arise from our analysis

    Editorial

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    Editorial

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