13,081 research outputs found

    Effect of the spin-orbit interaction and the electron phonon coupling on the electronic state in a silicon vacancy

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    The electronic state around a single vacancy in silicon crystal is investigated by using the Green's function approach. The triply degenerate charge states are found to be widely extended and account for extremely large elastic softening at low temperature as observed in recent ultrasonic experiments. When we include the LS coupling λSi\lambda_{\rm Si} on each Si atom, the 6-fold spin-orbital degeneracy for the V+V^{+} state with the valence +1 and spin 1/2 splits into Γ7\Gamma_{7} doublet groundstates and Γ8\Gamma_{8} quartet excited states with a reduced excited energy of O(λSi/10)O(\lambda_{\rm Si}/10). We also consider the effect of couplings between electrons and Jahn-Teller phonons in the dangling bonds within the second order perturbation and find that the groundstate becomes Γ8\Gamma_{8} quartet which is responsible for the magnetic-field suppression of the softening in B-doped silicon.Comment: 4 pages, 2 figure

    Power law burst and inter-burst interval distributions in the solar wind: turbulence or dissipative SOC ?

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    We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval tau for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P(e) and P(T) to be power laws, consistent with self-organised criticality (SOC). We find also a power law form for P(tau) that distinguishes this turbulent cascade from the exponential P(tau) of ideal SOC, but not from some other SOC-like sandpile models. We discuss the implications for the relation between SOC and turbulence.Comment: 3 pages, 1 figure. Submitted to PRL on 25th February 2000. Revised version re-submitted on 9th May 2000. Second revised version submitted Phys. Rev. E on 26th June, 200

    A sex difference in the context-sensitivity of dominance perceptions

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    Although dominance perceptions are thought to be important for effective social interaction, their primary function is unclear. One possibility is that they simply function to identify individuals who are capable of inflicting substantial physical harm, so that the perceiver can respond to them in ways that maximize their own physical safety. Another possibility is that they are more specialized, functioning primarily to facilitate effective direct (i.e., violent) intrasexual competition for mates, particularly among men. Here we used a priming paradigm to investigate these two possibilities. Facial cues of dominance were more salient to women after they had been primed with images of angry men, a manipulation known to activate particularly strong self-protection motivations, than after they had been primed with images of angry women or smiling individuals of either sex. By contrast, dominance cues were more salient to men after they had been primed with images of women than when they had been primed with images of men (regardless of the emotional expressions displayed), a manipulation previously shown to alter men's impressions of the sex ratio of the local population. Thus, men's dominance perceptions appear to be specialized for effective direct competition for mates, while women's dominance perceptions may function to maximize their physical safety more generally. Together, our results suggest that men's and women's dominance perceptions show different patterns of context-sensitivity and, potentially, shed new light on the routes through which violence and intrasexual competition have shaped dominance perceptions

    Multiple Criteria Analysis for Regional Water Quality Management: The Nitra River Case

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    This Working Paper documents the implementation of an element of a Decision Support System (DSS) for regional water quality management, applied in cooperation with the Water Research Institute (VUVH, Bratislava) and the Vah River Basin Authority to the Nitra River case study in Slovakia. Several re-usable, modular software tools have been developed and implemented -- a problem-specific generator to produce the core part of the mathematical programming model, tools for the generation and interactive modification of multicriteria problems, and a solver for the resulting mixed-integer optimization problem. Provided in the paper are the following: a complete formulation of the mathematical model (including the applied well-known dissolved oxygen model), a detailed discussion of the data used, documentation of the developed software, an overview of results which might be of interest, and recommendations for future work. Emphasis is placed on the advantages of multicriteria analysis for the regional water quality management problem

    Automated Retrieval of Non-Engineering Domain Solutions to Engineering Problems

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    Organised by: Cranfield UniversityBiological inspiration for engineering design has occurred through a variety of techniques such as creation and use of databases, keyword searches of biological information in natural-language format, prior knowledge of biology, and chance observations of nature. This research focuses on utilizing the reconciled Functional Basis function and flow terms to identify suitable biological inspiration for function based design. The organized search provides two levels of results: (1) associated with verb function only and (2) narrowed results associated with verb-noun (function-flow). A set of heuristics has been complied to promote efficient searching using this technique. An example for creating smart flooring is also presented and discussed.Mori Seiki – The Machine Tool Compan

    School violence, school differences and school discourses

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    This article highlights one strand of a study which investigated the concept of the violenceresilient school. In six inner-city secondary schools, data on violent incidents in school and violent crime in the neighbourhood were gathered, and compared with school practices to minimise violence, accessed through interviews. Some degree of association between the patterns of behaviour and school practices was found: schools with a wider range of wellconnected practices seemed to have less difficult behaviour. Interviews also showed that the different schools had different organisational discourses for construing school violence, its possible causes and the possible solutions. Differences in practices are best understood in connection with differences in these discourses. Some of the features of school discourses are outlined, including their range, their core metaphor and their silences. We suggest that organisational discourse is an important concept in explaining school effects and school differences, and that improvement attempts could have clearer regard to this concept

    Surgeon Specialty Influences Referral Rate for Osteoporosis Management Following Vertebral Compression Fractures

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    Study Design Retrospective chart review. Objective To evaluate the referral rate for long-term osteoporosis management following vertebral compression fracture treated by different specialties at a single academic institution. Methods Patients undergoing vertebral cement augmentation for painful osteoporotic compression fractures from 2009 to 2014 were identified. Medical records were reviewed to determine if the treating surgeon discussed and/or referred the patient for long-term osteoporosis management. Any referral for or mention of medical long-term osteoporosis management was counted as a positive response. Results were statistically analyzed with chi-square test. Results Two hundred fourteen patients underwent vertebral cement augmentation; 150 met inclusion criteria. Orthopedic surgeons treated 88 patients, neurosurgeons treated 39, and interventional radiology or pain management physicians treated 23. Orthopedic surgeons referred 82% of patients for osteoporosis management, neurosurgeons referred 36%, and interventional radiology/pain management referred 17%. The referral rate was significantly higher for orthopedic surgeons compared with either of the other two groups; there was no significant difference between neurosurgery and interventional radiology/pain management. Conclusions Among physicians who treat osteoporotic vertebral compression fractures, orthopedic surgeons more frequently address osteoporosis or refer patients for osteoporosis management compared with neurosurgeons and interventional radiologists or pain management physicians. The results of this study shed light on the disparity in how different specialties approach treatment of osteoporosis in patients with fractures painful enough to require surgery and highlight potential areas for improvement in osteoporosis awareness training
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