Causes Of Blackouts Research Articles

Editorial

The challenges and uncertainties of working in the developing field of Acute Medicine have been a regular theme for editorial comment in this journal since I took the helm in 2002. Almost four years on, with sub-specialty status confirmed, over 200 consultants and many SpRs enrolled in higher specialist training programmes throughout the UK, Acute Medicine finds itself in a much stronger position than any could have predicted at that time. Enthusiasm for the field is clear from the numbers of applicants for training programmes at SpR level, as well as the dramatic rise in attendances at acute medicine meetings across the country in the last year. However, on-going challenges remain. Eighteen months from now, Modernising Medical Careers will send shockwaves throughout hospital medicine. The exact nature of the change to our training programmes remains unclear, and will probably have changed again between my writing this and its publication. However it is essential that Acute Medicine is ready for whatever comes our way. We must work closely with our colleagues in Emergency Medicine and Critical Care to develop common stem training schemes which allow doctors to choose the area of ‘front door’ medicine which suits them best. Where possible we should seek to encourage dual accreditation in two or more of these areas. But most of all we need to maintain the momentum which has carried us so far in such a short space of time, and which has the potential to make Acute Medicine one of the largest hospital specialties. This edition’s review articles cover a varied mix of common and less common conditions on the acute medical ‘take’. Most medical admission units will be faced with at least one patient presenting with a seizure in each 24 hour period. Dr Kinton emphasises the importance of a good history in the management of this problem, but also provides some useful tips to help distinguish seizures from other causes of blackout. Distinction from syncope can be a particular challenge, not least because of the differing implications for driving, the loss of which can have devastating consequences. Acute ischaemic stroke is another common problem, the management of which is comprehensively reviewed by David Jarrett and Hemang Dave. As well as summarising some of the major trial data for thrombolytic and antiplatelet therapy, this review includes some advice on some of the common clinical challenges which don’t usually feature in text book descriptions of this condition. Less common, but no less important, Acute liver failure must be distinguished from decompensated chronic liver disease – the former often requiring discussion with a regional liver unit. Phil Berry has included a useful checklist to have to hand before making this phone call. Headache, palpitations and sweating is a common problem on the post-take ward round – particularly amongst the junior staff completing a night shift. Fortunately most junior doctors do not have a phaeochromocytoma – in common with every patient for whom I have ever requested 24 hour urinary catecholamine measurement. Having read Dr Solomon’s thorough review of the acute management of this condition I will now feel equipped to manage this condition when I finally get a positive result back from the laboratory! Apologies that this edition has been a little delayed – I hope you consider it to have been worth waiting for….

Critical points and transitions in an electric power transmission model for cascading failure blackouts.

Cascading failures in large-scale electric power transmission systems are an important cause of blackouts. Analysis of North American blackout data has revealed power law (algebraic) tails in the blackout size probability distribution which suggests a dynamical origin. With this observation as motivation, we examine cascading failure in a simplified transmission system model as load power demand is increased. The model represents generators, loads, the transmission line network, and the operating limits on these components. Two types of critical points are identified and are characterized by transmission line flow limits and generator capability limits, respectively. Results are obtained for tree networks of a regular form and a more realistic 118-node network. It is found that operation near critical points can produce power law tails in the blackout size probability distribution similar to those observed. The complex nature of the solution space due to the interaction of the two critical points is examined.(c) 2002 American Institute of Physics.

Probabilistic design of power-system special stability controls

A probabilistic approach to the design of power-system special stability controls is presented here. Using Monte-Carlo simulations, it takes into account all the potential causes of blackouts, slow and fast dynamics, and modeling uncertainties. A large number of scenarios are simulated in parallel by time-domain numerical integration, and the relevant parameters of the resulting system trajectories are stored in a database. Data-mining tools are used to identify the most important system weaknesses and possible improvements. The approach is tested on a large-scale study on the South–Eastern part of the extra-high-voltage system of Electricité de France.

Blackouts Not Obviously Due to Carotid Occlusion

Blackouts in one eye with numbness or motor symptoms on the opposite side of the body is now a well-recognized syndrome resulting from carotid occlusion. 1 Usually the diagnosis can be established ophthalmodynamometrically by finding relatively lower retinal arterial pressures on the affected side. What then are the causes of blackouts not resulting from carotid occlusion? The present paper reports a study of patients in whom blackouts were a presenting symptom but in whom the retinal arterial pressures and other cognate signs made it seem unlikely that carotid occlusion was the cause for their symptoms. The finding of retinal arterial pressures which were equal in the 2 eyes and in the normal range does not of course rule out the possibility of carotid occlusion. Nor does a significant inequality in the arterial pressures in the 2 eyes necessarily indict a carotid occlusion. Nevertheless, those cases of transient monocular blackouts wherein