Performance of a Neutron Polarimeter to Measure the Electric Form Factor of the Neutron

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Activity-based Discrete Event Simulation of Spatial Production Systems: application to fisheries

International audienceRelevant decision-making indicators and quantitative assessments are very strategic in management and production systems. In this paper, we present a modular and generic object framework using the Discrete EVent system Simulation Specification (DEVS) and the activity concept. We plan to simulate coastal fishery policies in the aim of improving harvesting and the management of fisheries. This work is a first step in employing Cellular Automata Models (CAM) with DEVS to design useful simulators in fisheries which are modelled as spatial production system

Are stock assessment methods too complicated? A critical review central on North Sea demersal stocks.

This critical review argues that several methods for the estimation and prediction of numbers-at-age, fishing mortality coefficients F, and recruitment for a stock of fish are too hard to explain to customers (the fishing industry, managers, etc.) and do not pay enough attention to weaknesses in the supporting data, assumptions and theory. The review is linked to North Sea demersal stocks. First, weaknesses in the various types of data used in North Sea assessments are summarized, i.e. total landings, discards, commercial and research vessel abundance indices, age-length keys and natural mortality (M). A list of features that an ideal assessment should have is put forward as a basis for comparing different methods. The importance of independence and weighting when combining different types of data in an assessment is stressed. Assessment methods considered are Virtual Population Analysis, ad hoc tuning, extended survivors analysis (XSA), year-class curves, catch-at-age modelling, and state-space models fitted by Kalman filter or Bayesian methods. Year-class curves (not to be confused with ‘catch-curves’) are the favoured method because of their applicability to data sets separately, their visual appeal, simple statistical basis, minimal assumptions, the availability of confidence limits, and the ease with which estimates can be combined from different data sets after separate analyses. They do not estimate absolute stock numbers or F but neither do other methods unless M is accurately known, as is seldom true

Efficacy of perindopril in reduction of cardiovascular events among patients with stable coronary artery disease: randomised, double-blind, placebo-controlled, multicentre trial (the EUROPA study)

BACKGROUND: Treatment with angiotensin-converting-enzyme (ACE) inhibitors reduces the rate of cardiovascular events among patients with left-ventricular dysfunction and those at high risk of such events. We assessed whether the ACE inhibitor perindopril reduced cardiovascular risk in a low-risk population with stable coronary heart disease and no apparent heart failure. METHODS: We recruited patients from October, 1997, to June, 2000. 13655 patients were registered with previous myocardial infarction (64%), angiographic evidence of coronary artery disease (61%), coronary revascularisation (55%), or a positive stress test only (5%). After a run-in period of 4 weeks, in which all patients received perindopril, 12218 patients were randomly assigned perindopril 8 mg once daily (n=6110), or matching placebo (n=6108). The mean follow-up was 4.2 years, and the primary endpoint was cardiovascular death, myocardial infarction, or cardiac arrest. Analysis was by intention to treat. FINDINGS: Mean age of patients was 60 years (SD 9), 85% were male, 92% were taking platelet inhibitors, 62% beta blockers, and 58% lipid-lowering therapy. 603 (10%) placebo and 488 (8%) perindopril patients experienced the primary endpoint, which yields a 20% relative risk reduction (95% CI 9-29, p=0.0003) with perindopril. These benefits were consistent in all predefined subgroups and secondary endpoints. Perindopril was well tolerated. INTERPRETATION: Among patients with stable coronary heart disease without apparent heart failure, perindopril can significantly improve outcome. About 50 patients need to be treated for a period of 4 years to prevent one major cardiovascular event. Treatment with perindopril, on top of other preventive medications, should be considered in all patients with coronary heart disease