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The modelling and analysis of systems reliability are critical in many industries. The costs associated with failure and its consequences provide a need for a clear description of the system in terms of a mathematical model that adequately reflects the nature of the system. As well as modelling systems it is necessary to consider the analysis of data from a system to assess the overall rate of the system failure. A smoothing approach is described to assess the overall performance of the system. Such methods lead to consideration of the time to the replacement of the system. This is determined by when the rate of occurrence of failures exceeds a certain threshold. The distribution of replacement times based on use of threshold values is investigated. The identification of the distributional family of the replacement time enables interval estimates to be obtained.

6-Keto-PGF1 alpha, PGF2 alpha and PGE2 production by homogenates of aorta was unaffected by age, sex or smoking habits. Homogenates of saphenous vein from women aged 51-60 years produced greater and smaller amounts of 6-keto- PGF1 alpha and PGF2 alpha, respectively, than from women aged 41-50 and 61-70 years. In the 41-50 and 61-70 age groups, the amounts of 6-keto-PGF1 alpha and PGF2 alpha produced by homogenates of saphenous vein were smaller and greater, respectively, in women than in men. Cigarette smoking had no effect on PG production by homogenates of female saphenous vein. 6-Keto-PGF1 alpha production by homogenates of male saphenous vein was 20% lower in smokers and ex-smokers than in non-smokers, although this reduction was statistically significant only for ex-smokers. The amounts of PGE2 and PGF2 alpha produced by homogenates of male saphenous vein were smaller in smokers and ex-smokers, respectively, than in non-smokers. In spite of these changes in PG production by homogenates of saphenous vein, the basal outputs of PGs, particularly of 6-keto-PGF1 alpha, from the saphenous vein were little affected by age, sex or smoking habits.

Carter, D. C., Forrest, J. A. H., Logan, R. A., Ansell, I., Lidgard, G., Heading, R. C. & Shearman, D. J. C. Effect of the histamine H2-receptor antagonist, cimetidine, on gastric secretion and ser...

Regression is the most frequently and widely applied technique in Statistics. The field of applications range from experimental design (historically in agriculture) to financial modelling. The technique has been greatly enhanced by the radical approach due to Nelder and Wedderburn. Their approach unified many apparently disparate applications of linear models to produce the Generalized Linear Model. Others have subsequently expanded their work. The paper briefly reviews this work indicating the main features which should be of interest to practitioners in many disciplines, e.g. education, sociology, medicine, economics, and the sciences. The original software developed from this approach was written in FORTRAN which the present authors believe constrained the development of a truly interactive package. APLIM, the first commercial APL version of the Generalized Linear Model is described. Stress is placed on a “user friendly” approach throughout the package. The authors have used APLIM to teach undergraduate students at the College Generalized Models, and a taste of their present teaching approach is given. The software has already been tested internally at the college by allowing other research workers access to it. The authors are at present working on a version for the IBM PC, aided by IBM UK.

Extravascular lung water (EVLW) has been measured by a non-invasive technique using 123 I-antipyrine and 113 Indium m -transferrin, as diffusible and non-diffusible indicators, and a gamma-camera computer system. Group A patients were normal radiologically and clinically. Group B patients were radiologically normal, clinically normal but were previously in heart failure and are currently on diuretics. Group C patients were radiologically normal, currently on diuretics with signs of pulmonary oedema. EVLW per unit blood flow and per unit blood volume were normal in Groups A and B but raised in Group C patients. The peak height to equilibrium ratio of the 123 I-antipyrine first pass curve was itself a useful discriminator in minimal pulmonary oedema.