2,957 research outputs found

    Onset of Localization in Heterogeneous Interfacial Failure

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    We study numerically the failure of an interface joining two elastic materials under load using a fiber bundle model connected to an elastic half space. We find that the breakdown process follows the equal load sharing fiber bundle model without any detectable spatial correlations between the positions of the failing fibers until localization sets in. The onset of localization is an instability, not a phase transition. Depending on the elastic constant describing the elastic half space, localization sets in before or after the critical load causing the interface to fail completely, is reached. There is a crossover between failure due to localization or failure without spatial correlations when tuning the elastic constant, not a phase transition. Contrary to earlier claims based on models different from ours, we find that a finite fraction of fibers must fail before the critical load is attained, even in the extreme localization regime, i.e.\ for very small elastic constant. We furthermore find that the critical load remains finite for all values of the elastic constant in the limit of an infinitely large system.Comment: 4 pages, 5 figure

    Code wars: steganography, signals intelligence, and terrorism

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    This paper describes and discusses the process of secret communication known as steganography. The argument advanced here is that terrorists are unlikely to be employing digital steganography to facilitate secret intra-group communication as has been claimed. This is because terrorist use of digital steganography is both technically and operationally implausible. The position adopted in this paper is that terrorists are likely to employ low-tech steganography such as semagrams and null ciphers instead

    Evolution and Diffusion of the Michigan State University Tradition of Organizational Communication Network Research

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    This article documents the 30-year history of communication network research at Michigan State University (M.S.U.), providing a case study of the evolution and diffusion of an academic innovation. Three past and continuing issues for network scholars are identified: a lack of professional reward for developing user-friendly computer programs, unresolved methodological problems, and a need for better theoretical and conceptual frameworks. The narrative also illustrates the difficulty communication as a discipline has in impacting broader intellectual traditions. The story begins with the first doctoral dissertation (Schwartz, 1968) and the first network analysis software program in 1970 (Richards’ Negopy), continuing to the last dissertation (Susskind, 1996), and ending in 1998 when J. David Johnson left the M.S.U. faculty. Other major players in the M.S.U. network tradition included David K. Berio, Eugene Jacobson, Everett M. Rogers, Vincent Farace, Peter Monge, and Erwin Bettinghaus. Ironically, Schwartz and Susskind met in 1998 while Schwartz was preparing to retire from Cornell University and Susskind was starting as an Assistant Professor in a different department, thus providing closure to the M.S.U. network

    Benzodiazepine and z-hypnotic prescribing from acute psychiatric inpatient discharge to long-term care in the community

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    Background: Benzodiazepine and z-hypnotic prescribing has slowly decreased over the past 20 years, however long-term chronic prescribing still occurs and is at odds with prescribing guidance. Objectives: To identify the pattern of benzodiazepine and z-hypnotic prescribing in psychiatric inpatients at discharge and 12 months post-discharge. Methods: Retrospective observational longitudinal cohort study of patients admitted to two adult psychiatric wards between June and November 2012 (inclusive) who were discharged with a prescription for a benzodiazepine or z-hypnotic drug. Routinely collected prescription data available from NHS Scotland Prescribing Information System was used to identify and follow community prescribing of benzodiazepine and z-hypnotics for a 12 month period post-discharge. Data were entered in Excel® and further analysed using SPSS 23. Ethical approval was not required for this service evaluation however Caldicott Guardian approval was sought and granted. Results: Eighty patients were admitted during the study period however only those patients with a single admission were included for analysis (n=74). Thirty per cent (22/74) of patients were prescribed a benzodiazepine or z-hypnotics at discharge; 14 of whom received ‘long-term’ benzodiazepine and z-hypnotics i.e. continued use over the 12 month period. Seven patients received a combination of anxiolytics and hypnotics (e.g., diazepam plus temazepam or zopiclone). Long-term use was associated with a non-significant increase in median benzodiazepine or z-hypnotic dose, expressed as diazepam equivalents. Conclusions: One in three patients were prescribed a benzodiazepine or z-hypnotics at discharge with 1 in 5 receiving continuous long-term treatment (prescriptions) for 12 months post-discharge. As chronic long-term B-Z prescribing and use still remains an issue, future strategies using routine patient-level prescribing data may support prescribers to review and minimise inappropriate long-term prescribing

    Quantum logic gates for coupled superconducting phase qubits

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    Based on a quantum analysis of two capacitively coupled current-biased Josephson junctions, we propose two fundamental two-qubit quantum logic gates. Each of these gates, when supplemented by single-qubit operations, is sufficient for universal quantum computation. Numerical solutions of the time-dependent Schroedinger equation demonstrate that these operations can be performed with good fidelity.Comment: 4 pages, 5 figures, revised for publicatio

    Implementation of geriatric assessment in oncology settings: A systematic realist review

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    Older adults with cancer are more likely to have worse clinical outcomes than their younger counterparts, and shared decision-making can be difficult, due to both complexity from adverse ageing and under-representation in clinical trials. Geriatric assessment (GA) has been increasingly recognised as a predictive and prehabilitative tool for older adults with cancer. However, GA has been notoriously difficult to implement in oncological settings due to workforce, economic, logistical, and practical barriers. We aimed to review the heterogenous literature on implementation of GA in oncology settings to understand the different implementation context configurations of GA and the mechanisms they trigger to enable successful implementation. A systematic realist review was undertaken in two stages: i) systematic searches with structured data extraction combined with iterative key stakeholder consultations to develop programme theories for implementing GA in oncology settings; ii) synthesis to refine programme theories. Medline, Embase, PsycInfo, Cochrane Library, CINAHL, Web of Science, Scopus, ASSIA, Epistemonikos, JBI Database of Systematic Reviews and Implementation Reports, DARE and Health Technology Assessment were searched. Four programme theories were developed from 53 included articles and 20 key stakeholder consultations addressing the major barriers of GA implementation in oncology practice: time (leveraging non-specialists), funding (creating favourable health economics), practicalities (establishing the use of GA in cancer care), and managing limited resources. We demonstrate that a whole system approach is required to improve the implementation of GA in cancer settings. This review will help inform policy decisions regarding implementation of GA and provide a basis for further implementation research

    Roughness of Interfacial Crack Front: Correlated Percolation in the Damage Zone

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    We show that the roughness exponent zeta of an in-plane crack front slowly propagating along a heterogeneous interface embeded in a elastic body, is in full agreement with a correlated percolation problem in a linear gradient. We obtain zeta=nu/(1+nu) where nu is the correlation length critical exponent. We develop an elastic brittle model based on both the 3D Green function in an elastic half-space and a discrete interface of brittle fibers and find numerically that nu=1.5, We conjecture it to be 3/2. This yields zeta=3/5. We also obtain by direct numerical simulations zeta=0.6 in excellent agreement with our prediction. This modelling is for the first time in close agreement with experimental observations.Comment: 4 pages RevTeX
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