Using FPGAs to prototype a self-timed floating point co-processor

Journal ArticleSelf- timed circuits offer advantages over their synchronously clocked counterparts in a number of situations. However, self-timed design techniques are not widely used at present for a variety of reasons. One reason for the lack of experimentation with self-timed systems is the lack of commercially available parts to support this style of design. Field programmable gate arrays (FPGAs) offer an excellent alternative for the rapid development of novel system designs provided suitable circuit structures can be implemented. This paper describes a self-timed floating point co-processor built using a combination of Actel Field Programmable Gate Arrays (FPGAs) and semi-custom CMOS chips. This co-processor implements IEEE standard single precision floating point operations on 32-bit values. The control is completely self-timed. Data moves between parts of the circuit according to local constraints only: there is no global clock or global control circuit

Aortic valve replacement in octogenarians

<p>Abstract</p> <p>Background and Aims</p> <p>As our population ages and life expectancy increases the number of people aged over 80 and more referred for cardiac surgery is growing. This study sought to identify the outcome of aortic valve replacement (AVR) in octogenarians.</p> <p>Methods</p> <p>68 patients aged 80 years or more underwent AVR at the Freeman Hospital, between April 2001 and April 2004. A retrospective review of the notes and outcomes from the patients' GP and the NHS strategic tracking service was performed. 54% (37) underwent isolated AVR whilst 46% (31) underwent combined AVR and CABG.</p> <p>Results</p> <p>Follow up was 100% complete. The mean age was 83.1 ± s.d. 2.9 years, a mean gradient of 83 ± s.d. 31 mmHg and mean AVA of 0.56 cm². The mean additive EuroSCORE was 8.6 ± s.d. 1.2, the logistic EuroSCORE mean 12.0 ± s.d. 5.9. In hospital 30 day mortality was 13 %. Survival was 80% at 1 year and 78% at 2 years. Median follow up was for 712 days. Stepwise logistic regression identified chronic obstructive airways disease as an independent predictor of mortality (p < 0.05). Survival was not adversely affected by the addition of coronary artery bypass grafts to aortic valve replacement, the presence of peripheral vascular disease, hypertension or diabetes. In this study duration of cross clamp or bypass time were not found to reach significance as independent predictors of mortality.</p> <p>Conclusion</p> <p>Our study demonstrates that the operative mortality for AVR in the over eighties is good, whilst the mid to long term outcome is excellent There is a very low attrition rate with those undergoing the procedure living as long than their age matched population. This study confirms AVR is a safe, acceptable treatment for octogenarians with excellent mid term outcomes.</p

Who Believes in the Giant Skeleton Myth? An Examination of Individual Difference Correlates

This study examined individual difference correlates of belief in a narrative about the discovery of giant skeletal remains that contravenes mainstream scientific explanations. A total of 364 participants from Central Europe completed a survey that asked them to rate their agreement with a short excerpt describing the giant skeleton myth. Participants also completed measures of the Big Five personality factors, New Age orientation, anti-scientific attitudes, superstitious beliefs, and religiosity. Results showed that women, as compared with men, and respondents with lower educational qualifications were significantly more likely to believe in the giant skeleton myth, although effect sizes were small. Correlational analysis showed that stronger belief in the giant skeleton myth was significantly associated with greater anti-scientific attitudes, stronger New Age orientation, greater religiosity, stronger superstitious beliefs, lower Openness to Experience scores, and higher Neuroticism scores. However, a multiple regression showed that the only significant predictors of belief in myth were Openness, New Age orientation, and anti-scientific attitudes. These results are discussed in relation to the potential negative consequences of belief in myths