314 research outputs found

    q-deformed dynamics and Josephson junction

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    We define a generalized rate equation for an observable in quantum mechanics, that involves a parameter q and whose limit q→1q\to 1 gives the standard Heisenberg equation. The generalized rate equation is used to study dynamics of current biased Josephson junction. It is observed that this toy model incorporates diffraction like effects in the critical current. Physical interpretation for q is provided which is also shown to be q-deformation parameter.Comment: LaTeX 9 pages, submitted Mod. Phys. Lett. B, e-mail: [email protected]

    Ignorance based inference of optimality in thermodynamic processes

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    We derive ignorance based prior distribution to quantify incomplete information and show its use to estimate the optimal work characteristics of a heat engine.Comment: Latex, 10 pages, 3 figure

    Work extremum principle: Structure and function of quantum heat engines

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    We consider a class of quantum heat engines consisting of two subsystems interacting via a unitary transformation and coupled to two separate baths at different temperatures Th>TcT_h > T_c. The purpose of the engine is to extract work due to the temperature difference. Its dynamics is not restricted to the near equilibrium regime. The engine structure is determined by maximizing the extracted work under various constraints. When this maximization is carried out at finite power, the engine dynamics is described by well-defined temperatures and satisfies the local version of the second law. In addition, its efficiency is bounded from below by the Curzon-Ahlborn value 1−Tc/Th1-\sqrt{T_c/T_h} and from above by the Carnot value 1−(Tc/Th)1-(T_c/T_h). The latter is reached|at finite power|for a macroscopic engine, while the former is achieved in the equilibrium limit Th→TcT_h\to T_c. When the work is maximized at a zero power, even a small (few-level) engine extracts work right at the Carnot efficiency.Comment: 16 pages, 5 figure

    Keeping the faith: reflections on religious nurture among young British Sikhs

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    Although young Sikhs are regularly accused of not attending gurdwara and not being interested in Sikhism, many young Sikhs are now learning about Sikhism outside traditional religious institutions. Using data gathered as part of a research project studying the transmission of Sikhism among 18- to 30-year-old British Sikhs, this essay explores how young Sikhs are learning about Sikhism in their pre-adult life stage. Examining the influences of the family and the school environment and the various methods used in gurdwaras, this essay offers a retrospective look on the ways in which young Sikhs are nurtured and socialised into Sikhism, providing an understanding from the perspective of young Sikhs themselves about which methods actually work and why

    Extended gaussian ensemble solution and tricritical points of a system with long-range interactions

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    The gaussian ensemble and its extended version theoretically play the important role of interpolating ensembles between the microcanonical and the canonical ensembles. Here, the thermodynamic properties yielded by the extended gaussian ensemble (EGE) for the Blume-Capel (BC) model with infinite-range interactions are analyzed. This model presents different predictions for the first-order phase transition line according to the microcanonical and canonical ensembles. From the EGE approach, we explicitly work out the analytical microcanonical solution. Moreover, the general EGE solution allows one to illustrate in details how the stable microcanonical states are continuously recovered as the gaussian parameter γ\gamma is increased. We found out that it is not necessary to take the theoretically expected limit γ→∞\gamma \to \infty to recover the microcanonical states in the region between the canonical and microcanonical tricritical points of the phase diagram. By analyzing the entropy as a function of the magnetization we realize the existence of unaccessible magnetic states as the energy is lowered, leading to a treaking of ergodicity.Comment: 8 pages, 5 eps figures. Title modified, sections rewritten, tricritical point calculations added. To appear in EPJ

    Negotiating their right to play: Asian-specific cricket teams and leagues in the UK and Norway

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    The cultural significance of ‘ethnic-specific’ cricket teams and leagues has received limited scholarly attention, despite increasing evidence of their various social functions. This paper aims to contribute to this under-researched area by drawing upon two individual case studies of Pakistani Muslim cricket teams; the first is based in the UK and the second in Norway. In this paper we argue that leisure and sport are key spaces for the delineation of social identities and hierarchies. We identify how cricket represents a significant social network within both the British and Norwegian Pakistani communities. In particular, we articulate the role of cricket in establishing and maintaining friendships and relationships, bolstering a sense of belonging, initiating diasporic sentiments, as well as being significant in the development of social capital, and resisting institutionalised white privilege

    Determination of the single-ion anisotropy energy in a S = 5/2 kagome antiferromagnet using x-ray absorption spectroscopy

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    We report x-ray absorption and x-ray linear dichroism measurements at the Fe L-2,L-3 edges of the geometrically frustrated systems of potassium and hydronium iron jarosite. Comparison with simulated spectra, involving ligand-field multiplet calculations modeling the 3d-2p hybridization between the iron ion and the oxygen ligands, has yielded accurate estimates for the ligand metal-ion hybridization and the resulting single-ion crystal-field anisotropy energy. Using this method we provide an experimentally verified scenario for the appearance of a single-ion anisotropy in this nominally high-spin 3d(5) orbital singlet S-6 system, which accounts for features of the spin-wave dispersion in the long-range-ordered ground state of potassium iron jarosite

    Is Total Hip Arthroplasty a Cost-Effective Option for Management of Displaced Femoral Neck Fractures? A Trial-Based Analysis of the HEALTH Study

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    BACKGROUND: Displaced femoral neck fractures are a significant source of morbidity and mortality and can be treated with either hemiarthroplasty (HA) or total hip arthroplasty (THA). Proponents of THA have argued THA offers lower risk of revision, with improved functional outcomes when compared to HA. To evaluate cost effectiveness of THA compared with HA, a trial-based economic analysis of the HEALTH study was undertaken. METHODS: Health care resource utilization (HRU) and health-related quality of life (HRQoL) data were collected postoperatively and costed using publicly available databases. Using EuroQol-5 Dimensions (EQ-5D) scores, we derived quality adjusted life years (QALYs). A 1.5% discount rate to both costs and QALYs was applied. Age analyses per age group were conducted. All costs are reported in 2019 Canadian dollars. RESULTS: When compared with HA, THA was not cost-effective for all patients with displaced femoral neck fractures (150,000/QALYgained).Ifdecisionmakerswerewillingtospend150,000/QALY gained). If decision makers were willing to spend 50,000 or $100,000 to gain one QALY, the probability of THA being cost-effective was 12.8% and 32.8%, respectively. In a subgroup of patients younger than 73 (first quartile), THA was both more effective and less costly. Otherwise, THA was more expensive and yielded marginal HRQoL gains. CONCLUSIONS: Our results suggest that for most patients, THA is not a cost-effective treatment for displaced femoral neck fracture management versus HA. However, THA may be cost effective for younger patients. These patients experience more meaningful improvements in quality of life with less associated cost because of shorter hospital stay and fewer postoperative complications. LEVEL OF EVIDENCE: Economic Level II. See Instructions for Authors for a complete description of levels of evidence

    A UK wide cohort study describing management and outcomes for infants with surgical Necrotising Enterocolitis

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    The Royal College of Surgeons have proposed using outcomes from necrotising enterocolitis (NEC) surgery for revalidation of neonatal surgeons. The aim of this study was therefore to calculate the number of infants in the UK/Ireland with surgical NEC and describe outcomes that could be used for national benchmarking and counselling of parents. A prospective nationwide cohort study of every infant requiring surgical intervention for NEC in the UK was conducted between 01/03/13 and 28/02/14. Primary outcome was mortality at 28-days. Secondary outcomes included discharge, post-operative complication, and TPN requirement. 236 infants were included, 43(18%) of whom died, and eight(3%) of whom were discharged prior to 28-days post decision to intervene surgically. Sixty infants who underwent laparotomy (27%) experienced a complication, and 67(35%) of those who were alive at 28 days were parenteral nutrition free. Following multi-variable modelling, presence of a non-cardiac congenital anomaly (aOR 5.17, 95% CI 1.9-14.1), abdominal wall erythema or discolouration at presentation (aOR 2.51, 95% CI 1.23-5.1), diagnosis of single intestinal perforation at laparotomy (aOR 3.1 95% CI 1.05-9.3), and necessity to perform a clip and drop procedure (aOR 30, 95% CI 3.9-237) were associated with increased 28-day mortality. These results can be used for national benchmarking and counselling of parents
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