924 research outputs found

    Robert Goadby, the Sherborne Mercury and the urban renaissance in south-west England

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    This is the author accepted manuscript. The final version is available from Cambridge Scholars Publishing via the DOI in this record

    Patients' experiences of brief cognitive behavioral therapy for eating disorders: A qualitative investigation

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    Objective Although it is important to analyze the effectiveness of new therapies, it is also necessary to consider how patients experience them. This is particularly important if we are to maximize treatment acceptability and reduce attrition. This study examined patient experiences of a new 10‐session cognitive‐behavioral therapy (CBT‐T), using a qualitative approach. Method The sample was 17 patients with a diagnosis of bulimia nervosa who had received CBT‐T (including treatment completers and non‐completers) within the previous 2 years. Sample size was determined by saturation of the emergent themes. Responses were analyzed using a six‐step thematic analysis process. Results Rated acceptability and effectiveness of CBT‐T were high. Five themes emerged, with subthemes. The key elements of patient experience of the therapy were: the therapeutic relationship; the nature of the therapy; its challenging but beneficial aspects; ending therapy; and the overall experience of CBT‐T (including comparison with other therapies). Discussion The findings build on the effectiveness research for CBT‐T, suggesting that it is an acceptable therapy that addresses many of the same themes that matter to patients as other therapies. The findings show that patients were positive about CBT‐T relative to other therapies, and offer suggestions as to how CBT‐T might be delivered to emphasize the importance of the time‐limited nature of the therapy

    Nonclassical correlations in continuous-variable non-Gaussian Werner states

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    We study nonclassical correlations beyond entanglement in a family of two-mode non-Gaussian states which represent the continuous-variable counterpart of two-qubit Werner states. We evaluate quantum discord and other quantumness measures obtaining exact analytical results in special instances, and upper and lower bounds in the general case. Non-Gaussian measurements such as photon counting are in general necessary to solve the optimization in the definition of quantum discord, whereas Gaussian measurements are strictly suboptimal for the considered states. The gap between Gaussian and optimal non-Gaussian conditional entropy is found to be proportional to a measure of non-Gaussianity in the regime of low squeezing, for a subclass of continuous-variable Werner states. We further study an example of a non-Gaussian state which is positive under partial transposition, and whose nonclassical correlations stay finite and small even for infinite squeezing. Our results pave the way to a systematic exploration of the interplay between nonclassicality and non-Gaussianity in continuous-variable systems, in order to gain a deeper understanding of -and to draw a bigger advantage from- these two important resources for quantum technology.Comment: References added, typos correcte

    Measurement-induced disturbances and nonclassical correlations of Gaussian states

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    We study quantum correlations beyond entanglement in two-mode Gaussian states of continuous variable systems, by means of the measurement-induced disturbance (MID) and its ameliorated version (AMID). In analogy with the recent studies of the Gaussian quantum discord, we define a Gaussian AMID by constraining the optimization to all bi-local Gaussian positive operator valued measurements. We solve the optimization explicitly for relevant families of states, including squeezed thermal states. Remarkably, we find that there is a finite subset of two-mode Gaussian states, comprising pure states, where non-Gaussian measurements such as photon counting are globally optimal for the AMID and realize a strictly smaller state disturbance compared to the best Gaussian measurements. However, for the majority of two--mode Gaussian states the unoptimized MID provides a loose overestimation of the actual content of quantum correlations, as evidenced by its comparison with Gaussian discord. This feature displays strong similarity with the case of two qubits. Upper and lower bounds for the Gaussian AMID at fixed Gaussian discord are identified. We further present a comparison between Gaussian AMID and Gaussian entanglement of formation, and classify families of two-mode states in terms of their Gaussian AMID, Gaussian discord, and Gaussian entanglement of formation. Our findings provide a further confirmation of the genuinely quantum nature of general Gaussian states, yet they reveal that non-Gaussian measurements can play a crucial role for the optimized extraction and potential exploitation of classical and nonclassical correlations in Gaussian states.Comment: 16 pages, 5 figures; new results added; to appear in Phys. Rev.
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