Instabilities and turbulence in highly ionized plasmas in a magnetic field Semiannual status report, 1 Sep. 1970 - 28 Feb. 1971

Instabilities and turbulence in highly ionized plasmas in magnetic field related to problems of thrustors for manned space flight and plasma generated energ

Irradiated asymmetric Friedmann branes

We consider a Friedmann brane moving in a bulk impregnated by radiation. The setup is strongly asymmetric, with only one black hole in the bulk. The radiation emitted by this bulk black hole can be reflected, absorbed or transmitted through the brane. Radiation pressure accelerates the brane, behaving as dark energy. Absorption however generates a competing effect: the brane becomes heavier and gravitational attraction increases. We analyse the model numerically, assuming a total absorbtion on the brane for k=1. We conclude that due to the two competing effects, in this asymmetric scenario the Hawking radiation from the bulk black hole is not able to change the recollapsing fate of this brane-world universe. We show that for light branes and early times the radiation pressure is the dominant effect. In contrast, for heavy branes the self-gravity of the absorbed radiation is a much stronger effect. We find the critical value of the initial energy density for which these two effects roughly cancel each other.Comment: 27 pages, 12 figure

Holistic hamstring health: not just the Nordic hamstring exercise

This was an editorial piece discussing the importance of a more holistic approach to hamstring conditioning

Use of blood lactate concentration as a marker of training status

The recent development of portable blood lactate analysers has made it relatively easy to test blood lactate concentration in the field. This paper discusses the validity and accuracy of measuring blood lactate concentration as a marker of training status or exercise intensity and examines the assumptions upon which the above practice is based. The mechanisms responsible for blood lactate accumulation according to different theories are discussed, followed by a review of the literature regarding the measurement, tracking and interpretation of blood lactate concentration. The use of blood lactate concentration to monitor either training status or intensity is complicated by the inaccuracy of portable lactate analysers, multiple confounding factors affecting blood lactate concentration such as carbohydrate depletion, mode of exercise, ambient temperature, muscle damage and overtraining and difficulty in interpreting the results. The relationship between changes in blood lactate concentration following training and subsequent performance in competition has not been convincingly established. Therefore it may be concluded that changes in blood lactate concentration should be interpreted with caution as the changes do not track training status or exercise intensity with sufficient precision to have a practical application

Cooperating Agents for 3D Scientific Data Interpretation

Many organizations collect vast quantities of three-dimensional (3-D) scientific data in volumetric form for a range of purposes, including resource exploration, market forecasting, and process modelling. Traditionally, these data have been interpreted by human experts with only minimal software assistance. However, such manual interpretation is a painstakingly slow and tedious process. Moreover, since interpretation involves subjective judgements and each interpreter has different scientific knowledge and experience, formulation of an effective interpretation often requires the cooperation of numerous such experts. Hence, there is a pressing need for a software system in which individual interpretations can be generated automatically and then refined through the use of cooperative reasoning and information sharing. To this end, a prototype system, SurfaceMapper, has been developed in which a community of cooperating software agents automatically locate and display interpretations in a volume of 3-D scientific data. The challenges and experiences in designing and building such a system are discussed. Particular emphasis is given to the agents' interactions and an empirical evaluation of the effectiveness of different cooperation strategies is presented

Perspectives on the Missiological Legacy of Martin Luther and the Protestant Reformation

Upon the occasion of the 500th anniversary Martin Luther’s publication of his 95 theses, this composite article brings together five perspectives on the missiological legacy of the reformer and the subsequent Protestant Reformation. The blend of voices makes clear that Luther and the subsequent Protestant Reformation do not have a simple missiological legacy but rather various legacies: theological, ecclesiological, political, and practical; some of which co-exist, and even collide, in the same ecclesiastical community. The scandalous legacy of a splintered and splintering church remains. Yet, demonstrations of mutual recognition, reciprocal respect, and genuine fellowship can be found in certain missiological circles

Entanglement and the Thermodynamic Arrow of Time

We discuss quantum entanglement in the context of the thermodynamic arrow of time. We review the role of correlations in entropy-decreasing events and prove that the occurrence of a transformation between two thermodynamic states constitutes a new type of entanglement witness, one not defined as a separating plane in state space between separable and entangled states, but as a physical process dependent on the local initial properties of the states. Extending work by Partovi, we consider a general entangled multipartite system that allows large reversals of the thermodynamic arrow of time. We describe a hierarchy of arrows that arises from the different correlations allowed in a quantum state and examine these features in the context of Maxwell's Demon. We examine in detail the case of three qubits, and also propose some simple experimental demonstrations possible with small numbers of qubits.Comment: 10 pages with 9 figure

Percutaneous coronary intervention in the elderly: changes in case-mix and periprocedural outcomes in 31758 patients treated between 2000 and 2007

<p>Background: The elderly account for an increasing proportion of the population and have a high prevalence of coronary heart disease. Percutaneous coronary intervention (PCI) is the most common method of revascularization in the elderly. We examined whether the risk of periprocedural complications after PCI was higher among elderly (age ≥75 years) patients and whether it has changed over time.</p> <p>Methods and Results: The Scottish Coronary Revascularization Register was used to undertake a retrospective cohort study on all 31 758 patients undergoing nonemergency PCI in Scotland between April 2000 and March 2007, inclusive. There was an increase in the number and percentage of PCIs undertaken in elderly patients, from 196 (8.7%) in 2000 to 752 (13.9%) in 2007. Compared with younger patients, the elderly were more likely to have multivessel disease, multiple comorbidity, and a history of myocardial infarction or coronary artery bypass grafting (χ2 tests, all P<0.001). The elderly had a higher risk of major adverse cardiovascular events within 30 days of PCI (4.5% versus 2.7%, χ2 test P<0.001). Over the 7 years, there was a significant increase in the proportion of elderly patients who had multiple comorbidity (χ2 test for trend, P<0.001). Despite this, the underlying risk of complications did not change significantly over time either among the elderly (χ2 test for trend, P=0.142) or overall (χ2 test for trend, P=0.083).</p> <p>Conclusions: Elderly patients have a higher risk of periprocedural complications and account for an increasing proportion of PCIs. Despite this, the risk of complications after PCI has not increased over time.</p&gt

Systematic Analysis Method for Color Transparency Experiments

We introduce a data analysis procedure for color transparency experiments which is considerably less model dependent than the transparency ratio method. The new method is based on fitting the shape of the A dependence of the nuclear cross section at fixed momentum transfer to determine the effective attenuation cross section for hadrons propagating through the nucleus. The procedure does not require assumptions about the hard scattering rate inside the nuclear medium. Instead, the hard scattering rate is deduced directly from the data. The only theoretical input necessary is in modelling the attenuation due to the nuclear medium, for which we use a simple exponential law. We apply this procedure to the Brookhaven experiment of Carroll et al and find that it clearly shows color transparency: the effective attenuation cross section in events with momentum transfer $Q^2$ is approximately $40\ mb\ (2.2\ GeV^2/Q^2)$. The fit to the data also supports the idea that the hard scattering inside the nuclear medium is closer to perturbative QCD predictions than is the scattering of isolated protons in free space. We also discuss the application of our approach to electroproduction experiments.Comment: 11 pages, 11 figures (figures not included, available upon request), report # KU-HEP-92-2