1,983 research outputs found
Defined Contribution Pension Plans in the Public Sector: A Benchmark Analysis
This chapter assesses best practice benchmarks for the design of defined contribution plans in the public sector, where such plans are the primary, or core, employment-based retirement benefit. These benchmarks rely on the notion that providing an adequate and secure retirement income for participants is the primary plan objective
Can billiard eigenstates be approximated by superpositions of plane waves?
The plane wave decomposition method (PWDM) is one of the most popular
strategies for numerical solution of the quantum billiard problem. The method
is based on the assumption that each eigenstate in a billiard can be
approximated by a superposition of plane waves at a given energy. By the
classical results on the theory of differential operators this can indeed be
justified for billiards in convex domains. On the contrary, in the present work
we demonstrate that eigenstates of non-convex billiards, in general, cannot be
approximated by any solution of the Helmholtz equation regular everywhere in
(in particular, by linear combinations of a finite number of plane waves
having the same energy). From this we infer that PWDM cannot be applied to
billiards in non-convex domains. Furthermore, it follows from our results that
unlike the properties of integrable billiards, where each eigenstate can be
extended into the billiard exterior as a regular solution of the Helmholtz
equation, the eigenstates of non-convex billiards, in general, do not admit
such an extension.Comment: 23 pages, 5 figure
Phase Control of Nonadiabaticity-induced Quantum Chaos in An Optical Lattice
The qualitative nature (i.e. integrable vs. chaotic) of the translational
dynamics of a three-level atom in an optical lattice is shown to be
controllable by varying the relative laser phase of two standing wave lasers.
Control is explained in terms of the nonadiabatic transition between optical
potentials and the corresponding regular to chaotic transition in mixed
classical-quantum dynamics. The results are of interest to both areas of
coherent control and quantum chaos.Comment: 3 figures, 4 pages, to appear in Physical Review Letter
Different Transport Pathways of Individual Precursor Proteins in Mitochondria
Transport of mitochondrial precursor proteins into mitochondria of Neurospora crassa was studied in a cellfree reconstituted system. Precursors were synthesized in a reticulocyte lysate programmed with Neurospora mRNA and transported into isolated mitochondria in the absence of protein synthesis. Uptake of the following precursors was investigated: apocytochrome c, ADP/ATP carrier and subunit 9 of the oligomycin-sensitive ATPase.
Addition of high concentrations of unlabelled chemically prepared apocytochrome c (1–10 μM) inhibited the appearance in the mitochondrial of labelled cytochrome c synthesized in vitro because the unlabelled protein dilutes the labelled one and because the translocation system has a limited capacity [apparent V is 1–3 pmol × min−1× (mg mitochondrial protein)−1]. Concentrations of added apocytochrome c exceeding the concentrations of precursor proteins synthesized in vitro by a factor of about 104 did not inhibit the transfer of ADP/ATP carrier or ATPase subunit 9 into mitochondria. Carbonylcyanide m-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, inhibited transfer in vitro of ADP/ATP carrier and of ATPase subunit 9, but not of cytochrome c.
These findings suggest that cytochrome c and the other two proteins have different import pathways into mitochondria. It can be inferred from the data presented that different 'receptors' on the mitochondrial surface mediate the specific recognition of precursor proteins by mitochondria as a first step in the transport process
Which health-related quality of life score? A comparison of alternative utility measures in patients with Type 2 diabetes in the ADVANCE trial.
BACKGROUND: Diabetes has a high burden of illness both in life years lost and in disability through related co-morbidities. Accurate assessment of the non-mortality burden requires appropriate health-related quality of life and summary utility measures of which there are several contenders. The study aimed to measure the impact of diabetes on various health-related quality of life domains, and compare several summary utility measures. METHODS: In the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation) study, 978 Australian patients with Type 2 diabetes completed two health-related quality of life questionnaires at baseline: the EQ-5D and the SF-36v2, from which nine summary utility measures were calculated, and compared. The algorithms were grouped into four classes: (i) based on the EQ-5D; (ii) using fewer items than those in the SF-12 (iii) using the items in the SF-12; and (iv) using all items of the SF-36. RESULTS: Overall health-related quality of life of the subjects was good (mean utility ranged from 0.68 (+/-0.08) to 0.85(+/-0.14) over the nine utility measures) and comparable to patients without diabetes. Summary indices were well correlated with each other (r = 0.76 to 0.99), and showed lower health-related quality of life in patients with major diabetes-related events such as stroke or myocardial infarction. Despite the smaller number of items used in the scoring of the EQ-5D, it generally performed at least as well as SF-36 based methods. However, all utility measures had some limitation such as limited range or ceiling effects. CONCLUSION: The summary utility measures showed good agreement, and showed good discrimination between major and minor health state changes. However, EQ-5D based measures performed as well and are generally simpler to use
The effects of perceived and received support on objective performance outcome.
This is a postprint of an article published in European Journal of Sport Science, 2008, Vol. 8, Issue 6, pp. 359 – 368 © 2008 copyright Taylor & Francis. European Journal of Sport Science is available online at: http://www.tandfonline.com/loi/tejs20In this study, we examined the main and stress-buffering effects of perceived and received support upon objective performance outcome. The sample consisted of 123 male British high performance golfers, mean age 25.3 years (SD = 5.4). Participants completed measures of perceived support, stressors, stress, and received support before competitions. After the competitions, performance outcome (number of shots) was recorded. When both types of support were considered separately, there were significant main effects for perceived (ΔR2 = .08, b = -.81, p < .01) and received support (ΔR2 = .05, b = -.68, p < .01) on performance. There were also significant stress-buffering effects for perceived (ΔR2 = .03, b = -.48, p = .02) and received support (ΔR2 = .06, b = -.61, p < .01). When both types of support were considered simultaneously, the significant main effect (DR2 = .09, p < .01) was primarily attributable to perceived support (b = -.63, p = .02). The significant stress-buffering effect (DR2 = .06, p = .01) was primarily attributable to received support (b = -.56, p = .04). These results demonstrate the beneficial influence of social support on performance. The findings highlight the need to recognise the distinction between perceived and received support, both in terms of theory and the design of social support interventions with athletes
Response to the letter to the editor regarding “Mobile phone use and brain tumour risk − COSMOS, a prospective cohort study”
Mobile phone use and brain tumour risk - COSMOS, a prospective cohort study
BACKGROUND: Each new generation of mobile phone technology has triggered discussions about potential carcinogenicity from exposure to radiofrequency electromagnetic fields (RF-EMF). Available evidence has been insufficient to conclude about long-term and heavy mobile phone use, limited by differential recall and selection bias, or crude exposure assessment. The Cohort Study on Mobile Phones and Health (COSMOS) was specifically designed to overcome these shortcomings. METHODS: We recruited participants in Denmark, Finland, the Netherlands, Sweden, and the UK 2007-2012. The baseline questionnaire assessed lifetime history of mobile phone use. Participants were followed through population-based cancer registers to identify glioma, meningioma, and acoustic neuroma cases during follow-up. Non-differential exposure misclassification was reduced by adjusting estimates of mobile phone call-time through regression calibration methods based on self-reported data and objective operator-recorded information at baseline. Hazard ratios (HR) and 95% confidence intervals (CI) for glioma, meningioma, and acoustic neuroma in relation to lifetime history of mobile phone use were estimated with Cox regression models with attained age as the underlying time-scale, adjusted for country, sex, educational level, and marital status. RESULTS: 264,574 participants accrued 1,836,479 person-years. During a median follow-up of 7.12 years, 149 glioma, 89 meningioma, and 29 incident cases of acoustic neuroma were diagnosed. The adjusted HR per 100 regression-calibrated cumulative hours of mobile phone call-time was 1.00 (95 % CI 0.98-1.02) for glioma, 1.01 (95 % CI 0.96-1.06) for meningioma, and 1.02 (95 % CI 0.99-1.06) for acoustic neuroma. For glioma, the HR for ≥ 1908 regression-calibrated cumulative hours (90th percentile cut-point) was 1.07 (95 % CI 0.62-1.86). Over 15 years of mobile phone use was not associated with an increased tumour risk; for glioma the HR was 0.97 (95 % CI 0.62-1.52). CONCLUSIONS: Our findings suggest that the cumulative amount of mobile phone use is not associated with the risk of developing glioma, meningioma, or acoustic neuroma
Response to the Letter to the Editor regarding “Mobile phone use and brain tumour risk − COSMOS, a prospective cohort study”
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