1,862 research outputs found

    Unifying Requirements and Code: an Example

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    Requirements and code, in conventional software engineering wisdom, belong to entirely different worlds. Is it possible to unify these two worlds? A unified framework could help make software easier to change and reuse. To explore the feasibility of such an approach, the case study reported here takes a classic example from the requirements engineering literature and describes it using a programming language framework to express both domain and machine properties. The paper describes the solution, discusses its benefits and limitations, and assesses its scalability.Comment: 13 pages; 7 figures; to appear in Ershov Informatics Conference, PSI, Kazan, Russia (LNCS), 201

    Optical study of the anisotropic erbium spin flip-flop dynamics

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    We investigate the erbium flip-flop dynamics as a limiting factor of the electron spin lifetime and more generally as an indirect source of decoherence in rare-earth doped insulators. Despite the random isotropic arrangement of dopants in the host crystal, the dipolar interaction strongly depends on the magnetic field orientation following the strong anisotropy of the gg-factor. In Er3+^{3+}:Y2_2SiO5_5, we observe by transient optical spectroscopy a three orders of magnitude variation of the erbium flip-flop rate (10ppm dopant concentration). The measurements in two different samples, with 10ppm and 50ppm concentrations, are well-supported by our analytic modeling of the dipolar coupling between identical spins with an anisotropic gg-tensor. The model can be applied to other rare-earth doped materials. We extrapolate the calculation to Er3+^{3+}:CaWO4_4, Er3+^{3+}:LiNbO3_3 and Nd3+^{3+}:Y2_2SiO5_5 at different concentrations

    Operational Semantics of Process Monitors

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    CSPe is a specification language for runtime monitors that can directly express concurrency in a bottom-up manner that composes the system from simpler, interacting components. It includes constructs to explicitly flag failures to the monitor, which unlike deadlocks and livelocks in conventional process algebras, propagate globally and aborts the whole system's execution. Although CSPe has a trace semantics along with an implementation demonstrating acceptable performance, it lacks an operational semantics. An operational semantics is not only more accessible than trace semantics but also indispensable for ensuring the correctness of the implementation. Furthermore, a process algebra like CSPe admits multiple denotational semantics appropriate for different purposes, and an operational semantics is the basis for justifying such semantics' integrity and relevance. In this paper, we develop an SOS-style operational semantics for CSPe, which properly accounts for explicit failures and will serve as a basis for further study of its properties, its optimization, and its use in runtime verification

    Impact of washing and sterilization on properties of fabrics used for medical applications

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    This paper reports a study on the characterization of cellulosic, polyester/cotton (PES/cotton) and Tencel fabrics as well as PES/PU/PES laminate used for medical applications, before and after frequent washing and sterilization. The impact of washing and sterilization is analysed by tensile properties, spectral changes and surface characterization. The results indicate that, during washing and sterilization, cellulosic fabrics show prominent changes of all studied properties when compared to PES/PU/PES laminate

    Superhyperfine induced photon-echo collapse of erbium in Y2_2SiO5_5

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    We investigate the decoherence of Er3+^{3+} in Y2_2SiO5_5 at low magnetic fields using the photon-echo technique. We reproduce accurately a variety of the decay curves with a unique coherence time by considering the so-called superhyperfine modulation induced by a large number of neighbouring spins. There is no need to invoke any characteristic time of the spin fluctuations to reproduce very different decay curves. The number of involved nuclei increases when the magnetic is lowered. The experiment is compared with a model associating 100 surrounding ions with their exact positions in the crystal frame. We also derive an approximate spherical model (angular averaging) to interpret the main feature the observed decay curves close to zero-field

    Protocol for a scoping review on information needs and information-seeking behaviour of people with dementia and their non-professional caregivers

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    Background: Dementia is a debilitating disease that can lead to major changes in a patient’s behaviour and function. It is important to educate both dementia patients and their non-professional caregivers about the disease. Yet, currently available sources do not seem to be effective for patients and caregivers, who report a need for more information and guidance. A systematic identification of the patients’ and caregivers’ needs for information and information seeking behaviour is needed to create information resources that are relevant and beneficial to the target population. Objective: This is a protocol for a scoping review aimed at gathering knowledge on the information needs and information seeking behaviour of dementia patients and their non- professional caregivers. Our aim is also to provide recommendations for development of future dementia information resources. Methods: The study will commence in November 2018. Both quantitative and qualitative studies on the information needs of dementia patients or caregivers will be examined using Arksey and O’Malley’s methodological framework for scoping studies. A comprehensive literature search will be conducted in electronic databases and grey literature sources. We will also screen reference lists of included studies and related systematic reviews for additional eligible studies. Two authors will perform screening of citations for eligibility, and independently extract data from the included studies in parallel. Any discrepancies will be resolved through discussion. The findings will be presented through a narrative synthesis and reported in line with PRISMA reporting guidelines. Ethics and dissemination: In this review, all included data will originate from published literature. Ethics approval is therefore not a requirement. We will present our findings at relevant conferences and will submit them for publication in peer-reviewed journals. Strengths and limitations of this study • In this scoping review, we will perform a comprehensive search of electronic databases and grey literature sources to identify up-to-date evidence on information needs and information seeking behaviour of dementia patients and their informal caregivers. • We will seek to identify evidence on information needs and information seeking behaviour of both dementia patients and their caregivers. • As this is a scoping review, a formal quality and risk of bias assessment of the included literature will not be performed. • This review will only include studies published in English

    Ab initio Molecular Dynamics in Adaptive Coordinates

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    We present a new formulation of ab initio molecular dynamics which exploits the efficiency of plane waves in adaptive curvilinear coordinates, and thus provides an accurate treatment of first-row elements. The method is used to perform a molecular dynamics simulation of the CO_2 molecule, and allows to reproduce detailed features of its vibrational spectrum such as the splitting of the Raman sigma+_g mode caused by Fermi resonance. This new approach opens the way to highly accurate ab initio simulations of organic compounds.Comment: 11 pages, 3 PostScript figure

    Achieving provider engagement: providers' perceptions of implementing and delivering integrated care

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    The literature on integrated care is limited with respect to practical learning and experience. Although some attention has been paid to organizational processes and structures, not enough is paid to people, relationships, and the importance of these in bringing about integration. Little is known, for example, about provider engagement in the organizational change process, how to obtain and maintain it, and how it is demonstrated in the delivery of integrated care. Based on qualitative data from the evaluation of a large-scale integrated care initiative in London, United Kingdom, we explored the role of provider engagement in effective integration of services. Using thematic analysis, we identified an evolving engagement narrative with three distinct phases: enthusiasm, antipathy, and ambivalence, and argue that health care managers need to be aware of the impact of professional engagement to succeed in advancing the integrated care agenda

    Optical properties of the vibrations in charged C60_{60} molecules

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    The transition strengths for the four infrared-active vibrations of charged C60_{60} molecules are evaluated in self-consistent density functional theory using the local density approximation. The oscillator strengths for the second and fourth modes are strongly enhanced relative to the neutral C60_{60} molecule, in good agreement with the experimental observation of ``giant resonances'' for those two modes. Previous theory, based on a ``charged phonon'' model, predicted a quadratic dependence of the oscillator strength on doping, but this is not borne out in our calculations.Comment: 10 pages, RevTeX3.
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