The persistent vegetative state: legal and ethical issues

Recent advances in technology and medical expertise have enabled doctors to prolong the lives of many severely injured patients who only a few years ago would have died from their injuries. The prolongation of life by such measures has raised many legal, ethical and social issues. When in 1992 the House of Lords determined in Airdale NHS Trust V Bland that life-supporting measures, including artificial nutrition and hydration (ANH) might lawfully be withdrawn from Anthony Bland, a patient in a persistent vegetative state (PVS), attention was focused on these issues particularly as they apply to the patient in PVS. Since the PVS patient is neither competent to refuse treatment, nor is he dying or suffering, the reasons normally advanced for withdrawing life-supporting measures do not apply. In Bland, their Lordships relied on the best interests test laid down in Re F (mental patient: sterilisation) [1989] 2 All ER 545, and, with the exception of Lord Mustill, on the Bolam test (Bolam v Friern Barnet Hospital Management Committee) [1957] 1 WLR 582. This thesis examines the decision mBland and addresses some of the issues raised. The appropriateness of the best interests test as applied to the patient in PVS is explored and compared with the approach of substituted judgement employed in some other common law jurisdictions. The relevance of the Bolam test to decisions regarding the withdrawal of life-supporting measures is considered. The legal requirements for the withdrawal of ANH are discussed, together with the ethical debate and the moral dilemmas posed by its withdrawal. Finally, the question as to whether the decision in Bland is good law is addressed, and it will be argued that whilst it may be morally acceptable to withdraw ANH from some patients, as regards a patient in PVS, the moral imperative is that we should not

Cascading Power Outages Propagate Locally in an Influence Graph that is not the Actual Grid Topology

In a cascading power transmission outage, component outages propagate non-locally, after one component outages, the next failure may be very distant, both topologically and geographically. As a result, simple models of topological contagion do not accurately represent the propagation of cascades in power systems. However, cascading power outages do follow patterns, some of which are useful in understanding and reducing blackout risk. This paper describes a method by which the data from many cascading failure simulations can be transformed into a graph-based model of influences that provides actionable information about the many ways that cascades propagate in a particular system. The resulting "influence graph" model is Markovian, in that component outage probabilities depend only on the outages that occurred in the prior generation. To validate the model we compare the distribution of cascade sizes resulting from $n-2$ contingencies in a $2896$ branch test case to cascade sizes in the influence graph. The two distributions are remarkably similar. In addition, we derive an equation with which one can quickly identify modifications to the proposed system that will substantially reduce cascade propagation. With this equation one can quickly identify critical components that can be improved to substantially reduce the risk of large cascading blackouts.Comment: Accepted for publication at the IEEE Transactions on Power System

On the Andrews congruence for the Fibonacci quotient

We show that a congruence discovered by George E. Andrews in 1969 for the Fibonacci quotient directly implies a simpler congruence found by Hugh C. Williams in 1991

Chain-store pricing for strategic accommodation

Chain-stores now dominate most areas of retailing. While retailers may operate nationally or even internationally, the markets they compete in are largely local. How should they best operate pricing policy in respect of the different markets served - price uniformly across the local markets or on a local basis according to market conditions? We model this by allowing local market differences, with entry being inevitable in certain markets while being naturally or institutionally blockaded in others. We show that practising price discrimination is not always best for the chain-store. Competitive conditions exist under which uniform pricing can raise profits

Independent Component Analysis for Improved Defect Detection in Guided Wave Monitoring

Guided wave sensors are widely used in a number of industries and have found particular application in the oil and gas industry for the inspection of pipework. Traditionally this type of sensor was used for one-off inspections, but in recent years there has been a move towards permanent installation of the sensor. This has enabled highly repeatable readings of the same section of pipe, potentially allowing improvements in defect detection and classification. This paper proposes a novel approach using independent component analysis to decompose repeat guided wave signals into constituent independent components. This separates the defect from coherent noise caused by changing environmental conditions, improving detectability. This paper demonstrates independent component analysis applied to guided wave signals from a range of industrial inspection scenarios. The analysis is performed on test data from pipe loops that have been subject to multiple temperature cycles both in undamaged and damaged states. In addition to processing data from experimental damaged conditions, simulated damage signals have been added to “undamaged” experimental data, so enabling multiple different damage scenarios to be investigated. The algorithm has also been used to process guided wave signals from finite element simulations of a pipe with distributed shallow general corrosion, within which there is a patch of severe corrosion. In all these scenarios, the independent component analysis algorithm was able to extract the defect signal, rejecting coherent noise

Extended calculations of a special Harmonic number

The search for values of $p$ for which the Harmonic numbers $H_{\lfloor p/6 \rfloor}$ vanish mod $p$, carried to $p < 600,000$ by Schwindt in 1983, is extended here to $p < 16,949,000,000,000$, and two new solutions are reported