On spatial conditional extremes for ocean storm severity.

We describe a model for the conditional dependence of a spatial process measured at one or more remote locations given extreme values of the process at a conditioning location, motivated by the conditional extremes methodology of Heffernan and Tawn. Compared to alternative descriptions in terms of max-stable spatial processes, the model is advantageous because it is conceptually straightforward and admits different forms of extremal dependence (including asymptotic dependence and asymptotic independence). We use the model within a Bayesian framework to estimate the extremal dependence of ocean storm severity (quantified using significant wave height, ) for locations on spatial transects with approximate east-west (E-W) and north-south (N-S) orientations in the northern North Sea (NNS) and central North Sea (CNS).

The UK nephrostomy audit. Can a voluntary registry produce robust performance data?

Aim: To investigate the effectiveness of the Royal College of Radiologists Audit Sub-Committee's national prospective registry of percutaneous nephrostomy, which enables participants to audit their practice and compare performance with predetermined standards.

Methods: Following a limited retrospective audit, which permitted setting of achievable targets, a dataset was developed and all UK NHS acute hospitals were invited to participate in web-based prospective data collection.

Results: Eighty-five out of 285 (29.

Bayesian modelling of extreme surges on the UK east coast.

The catastrophic surge event of 1953 on the eastern UK and northern European coastlines led to widespread agreement on the necessity of a coordinated response to understand the risk of future oceanographic flood events and, so far as possible, to afford protection against such events. One element of this response was better use of historical data and scientific knowledge in assessing flood risk. The timing of the event also coincided roughly with the birth of extreme value theory as a statistical discipline for measuring risks of extreme events, and over the last 50 years, as techniques have been developed and refined, various attempts have been made to improve the precision of flood risk assessment around the UK coastline.

Role of subintimal angioplasty in the treatment of chronic lower limb ischaemia.

Objectives: To determine the clinical outcome of subintimal angioplasty (SA) and to assess impact on surgical workload.

Design: Retrospective review of a single radiologist's case series.

Materials: One hundred and twenty two patients with critical limb ischaemia and 26 with claudication.