2,341 research outputs found

    Effects of northbound long-haul international air travel on sleep quantity and subjective jet lag and wellness in professional Australian soccer players

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    © 2015 Human Kinetics, Inc. The current study examined the effects of 10-h northbound air travel across 1 time zone on sleep quantity, together with subjective jet lag and wellness ratings, in 16 male professional Australian football (soccer) players. Player wellness was measured throughout the week before (home training week) and the week of (away travel week) travel from Australia to Japan for a preseason tour. Sleep quantity and subjective jet lag were measured 2 d before (Pre 1 and 2), the day of, and for 5 d after travel (Post 1-5). Sleep duration was significantly reduced during the night before travel (Pre 1; 4.9 [4.2-5.6] h) and night of competition (Post 2; 4.2 [3.7-4.7] h) compared with every other night (P 0.90). Moreover, compared with the day before travel, subjective jet lag was significantly greater for the 5 d after travel (P 0.90), and player wellness was significantly lower 1 d postmatch (Post 3) than at all other time points (P 0.90). Results from the current study suggest that sleep disruption, as a result of an early travel departure time (8 PM) and evening match (7:30 PM), and fatigue induced by competition had a greater effect on wellness ratings than long-haul air travel with a minimal time-zone change. Furthermore, subjective jet lag may have been misinterpreted as fatigue from sleep disruption and competition, especially by the less experienced players. Therefore, northbound air travel across 1 time zone from Australia to Asia appears to have negligible effects on player preparedness for subsequent training and competition

    Large deviations for clocks of self-similar processes

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    The Lamperti correspondence gives a prominent role to two random time changes: the exponential functional of a L\'evy process drifting to ∞\infty and its inverse, the clock of the corresponding positive self-similar process. We describe here asymptotical properties of these clocks in large time, extending the results of Yor and Zani

    Computable bounds in fork-join queueing systems

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    In a Fork-Join (FJ) queueing system an upstream fork station splits incoming jobs into N tasks to be further processed by N parallel servers, each with its own queue; the response time of one job is determined, at a downstream join station, by the maximum of the corresponding tasks' response times. This queueing system is useful to the modelling of multi-service systems subject to synchronization constraints, such as MapReduce clusters or multipath routing. Despite their apparent simplicity, FJ systems are hard to analyze. This paper provides the first computable stochastic bounds on the waiting and response time distributions in FJ systems. We consider four practical scenarios by combining 1a) renewal and 1b) non-renewal arrivals, and 2a) non-blocking and 2b) blocking servers. In the case of non blocking servers we prove that delays scale as O(logN), a law which is known for first moments under renewal input only. In the case of blocking servers, we prove that the same factor of log N dictates the stability region of the system. Simulation results indicate that our bounds are tight, especially at high utilizations, in all four scenarios. A remarkable insight gained from our results is that, at moderate to high utilizations, multipath routing 'makes sense' from a queueing perspective for two paths only, i.e., response times drop the most when N = 2; the technical explanation is that the resequencing (delay) price starts to quickly dominate the tempting gain due to multipath transmissions

    Identifying Challenging Job and Environmental Demands of Older Nurses Within the National Health Service

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    Objectives: To explore the existing theoretical contexts of the job and environmental demands of the nursing profession in the National Health Service (NHS) and to investigate how these job and environmental demands impact on the personal constructs of older nurses within the NHS. Background: Nursing is the single most widely practiced profession in the healthcare sector in the United Kingdom. However, nurses contend with challenging job and environmental demands on a daily basis, which deplete them of personal constructs (or resources) required to stay in the profession. Methods: A multilevel exploratory qualitative research design was employed. Ten managers were interviewed for the preliminary study, based on which the three characteristics of an age-friendly NHS workplace were established: health, retirement, and flexibility. Then an in-depth literature review revealed that the most adversely affected job within the NHS was the nursing profession. Finally, a focus group study was undertaken with six older nurses working in the NHS. Results: The most compelling finding of this study is that older nurses would generally not want to stay on the job if they had to work in the ward area. The physical, cognitive, and sensory constructs of older nurses are negatively affected by the job and environmental demands of the ward areas. Conclusions: Understanding how these job and environmental demands of the workplace affect an older nurse’s personal constructs may help support a better design of nurse work and the wards and help extend the working lives of older nurses in the NHS

    Security governance and networks: New theoretical perspectives in transatlantic security

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    The end of the Cold War has not only witnessed the rise of new transnational threats such as terrorism, crime, proliferation and civil war; it has also seen the growing role of non-state actors in the provision of security in Europe and North America. Two concepts in particular have been used to describe these transformations: security governance and networks. However, the differences and potential theoretical utility of these two concepts for the study of contemporary security have so far been under-examined. This article seeks to address this gap. It proposes that security governance can help to explain the transformation of Cold War security structures, whereas network analysis is particularly useful for understanding the relations and interactions between public and private actors in the making and implementation of national and international security policies

    The clinical and pathological features of hereditary mixed polyposis syndrome: report on a South African family

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    Background: Hereditary mixed polyposis syndrome is characterised by multiple large-bowel polyps of differing histological types including a mixture of atypical juvenile polyps, hyperplastic polyps and adenomas. Affected individuals are thought to have an increased risk of malignancy, possibly via the juvenile polyposis pathway. Methods: A 51-year-old woman (with a history of a colectomy for polyps during childhood) presented with rectal bleeding. Endoscopy demonstrated small rectal polyps which were hyperplastic on histology. A family tree was drawn up and the three children of the proband underwent flexible sigmoidoscopy. Results: Endoscopic surveillance of the three children revealed one who had a similar phenotype to the mother. This child underwent colectomy and ileorectal anastomosis. The pathological specimen revealed more than 70 polyps, with a combination of juvenile retention, hyperplastic, adenomatous and inflammatory polyps. A second child had multiple small hyperplastic polyps, and the third had a normal colon. Although the gene locus for the disorder has been mapped, neither the gene nor the disease-causing mutation has been defined. Conclusion: A rare inherited polyposis syndrome has been identified in a South African family. Where clinical suspicion of a possible inherited condition exists, investigating at-risk first-degree relatives confirms the inherited nature of the disease. It is possible to use genetic haplotyping (i.e. with a range of markers in the area of the gene) to provide statistical risk to immediate relatives and therefore those at highest risk

    Desperately constructing ethnic audiences: Anti-immigration discourses and minority audience research in the Netherlands

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    This article examines how minority ethnic audiences are measured, and thus constructed, in the Netherlands today. The analysis shows that this process is tightly woven into the dominant assimilationist and neoliberal discourse. This discourse portrays specific minority groups as deviant in relation to an essentialized notion of Dutchness. Furthermore, it presents social inclusion as an opportunity that is limited to well-adjusted, profitable consumers. Different attempts to represent minority audiences – including efforts to promote a more just minority representation in Dutch media – are compelled to accommodate to this dominant discourse. The article underscores the limited scope for contesting current hegemonic representations of minority groups and national belonging in the Netherlands

    Sparsity without the Complexity: Loss Localisation using Tree Measurements

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    We study network loss tomography based on observing average loss rates over a set of paths forming a tree -- a severely underdetermined linear problem for the unknown link loss probabilities. We examine in detail the role of sparsity as a regularising principle, pointing out that the problem is technically distinct from others in the compressed sensing literature. While sparsity has been applied in the context of tomography, key questions regarding uniqueness and recovery remain unanswered. Our work exploits the tree structure of path measurements to derive sufficient conditions for sparse solutions to be unique and the condition that ℓ1\ell_1 minimization recovers the true underlying solution. We present a fast single-pass linear algorithm for ℓ1\ell_1 minimization and prove that a minimum ℓ1\ell_1 solution is both unique and sparsest for tree topologies. By considering the placement of lossy links within trees, we show that sparse solutions remain unique more often than is commonly supposed. We prove similar results for a noisy version of the problem

    Transnational policy entrepreneurs and the cultivation of influence : individuals, organizations and their networks

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    The ‘policy entrepreneur’ concept arises from the Multiple Streams’ theory of agenda setting in Policy Studies. Through conceptual stretching’, the concept is extended to global policy dynamics. Unlike ‘advocacy networks’ and ‘norm entrepreneurs’, the discussion addresses the strategies of ‘insider’ or ‘near-governmental’ non-state actors. The analysis advances the policy entrepreneur concept in three directions. First, the discussion develops the transnational dimensions of this activity through a case study of International Crisis Group. Second, rather than focusing on charismatic individuals, the discussion emphasizes the importance of organizational resources and reputations for policy entrepreneurship and access into international policy communities. Organizations maintain momentum behind policy solutions and pressures for change over the long term when individuals retire or depart for other positions. Third, the discussion outlines four distinct entrepreneur strategies and techniques that both individuals and organizations cultivate and deploy to enhance their power and persuasion in global policy processes and politics

    Microscopic Foundation of Nonextensive Statistics

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    Combination of the Liouville equation with the q-averaged energy Uq=qU_q = _q leads to a microscopic framework for nonextensive q-thermodynamics. The resulting von Neumann equation is nonlinear: iρ˙=[H,ρq]i\dot\rho=[H,\rho^q]. In spite of its nonlinearity the dynamics is consistent with linear quantum mechanics of pure states. The free energy Fq=Uq−TSqF_q=U_q-TS_q is a stability function for the dynamics. This implies that q-equilibrium states are dynamically stable. The (microscopic) evolution of ρ\rho is reversible for any q, but for q≠1q\neq 1 the corresponding macroscopic dynamics is irreversible.Comment: revte
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