Stability of time-tradeoff utilities in survivors of myocardial infarction

To investigate whether time-tradeoff utilities of survivors of myocardial infarction change over time and whether changes in utilities correlate with changes in functional status, the authors conducted serial interviews using a time tradeoff and three measures of functional status in a cohort of 67 patients who had recently had myocardial infarction. The patients were also asked to rate their overall health on a rating scale and were asked about chest pain, exercise status, and employment status. Each patient was interviewed two to five times over one and a half years. The mean (95% CI) time-tradeoff score for all patients was 0.88 (0.84, 0.93). Over a mean interval of 8.4 months, 28 (42%) patients changed Karnofsky scores, 28 (42%) changed Specific Activity Scale classes, and 11 (16%) changed New York Heart Association classes, with most changes representing improvements in functional status. Scores on the rating scale improved by a mean (95% CI) of 0.06 [(0.03, 0.10); p < 0.002], but scores on the time tradeoff remained stable, with a mean (95% CI) change of 0.03 [(-0.02, 0.08); p = NS]. Changes in time-tradeoff scores did not correlate with changes in Specific Activity Scale classes (Kendall's tau = 0.21), New York Heart Association classes (tau = -0.02), or Karnofsky scores (tau = 0.14); with changes on the verbal rating scale (R = 0.20); with changes in chest pain status (tau = -0.05), exercise status (tau = 0.11), or employment status (tau = 0.11); or with interim hospitalizations (tau = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of acoustic emissions from polymers

Acoustic emissions obtained from polymers under stress have been subjected to various mathematical analyses with the objective of relating the observed signals to accompanying chemical and physical changes in the polymer. The following methods have been investigated: frequency analysis, autocor-relation analysis, cepstrum analysis and cluster analysis (pattern recognition). It is shown that it is possible to classify the signals from a given polymer sample into relatively few types and that there is a periodicity in a number of plots of acoustic power vs time. Differences between samples are evident, although it is not possible at this stage to state that they are statistically significant. The materials examined include, nylon-6,6, ‘Diakon’, polypropylene and various composites.     

High finesse ring resonators made by silver ion exchange in glass

We report the fabrication of single tap ring resonators made by thermal silver ion-exchange in various types of glass substrates. The highest finesse achieved was 55 with an efficiency of 32 percent. We systematically measured losses arising from different sources such as intrinsic absorption in the glass and scattering from side wall roughness arising from the mask fabrication technique. All data was measured atlambda = 0.6328 mum.     

An Analysis of the Effect of Lubricant Supply Rate on the Performance of the 360° Journal Bearing

A theoretical study was made to determine the influence of lubricant supply rate on the performance of the 360° journal bearing for L/D = 1. The results are presented in chart form to facilitate their application to analysis and design.