Proposal for a race-track microtron with high peak current

In order to obtain high gain in a free electron laser a high-quality electron beam with high peak current is required. It is well-known that a microtron is able to produce a high-quality beam having low emittance and small energy spread (1%). Because a circular microtron has a limited high-current capability a race-track design is adopted for providing flexibility, better beam quality and of course higher peak current in the microbunch. Space charge problems may be severe in a microtron. It can be shown that bunching on certain specific subharmonic frequencies will lead to a strong reduction of the space charge problems. The general layout of our microtron design will be presented. The characteristics are: energy 25 MeV, micropulse 10° of the rf frequency of 3 GHz. Our aim is to come beyond the present state of the art with the following characteristics: relative energy spread 0.001, emittance 3 mm mrad, current in the micropulse 100 A, macropulse length 50 μs and subharmonic bunching at 1:64

High pressure X-ray preionized TEMA-CO2 laser

The construction of a high-pressure (up to 20 atm) transversely excited CO2 laser using transverse X-ray preionization is described. High pressure operation was found to be greatly improved in comparison to UV-preionized systems. Homogeneous discharges have been achieved in the pressure range 5–20 atm, yielding a specific laser output in the order of 35 J/l

Serum cholesterol is a risk factor for myocardial infarction in elderly men and women: The Rotterdam Study

Objective. To investigate the associations of serum total and HDL cholesterol with the risk of myocardial infarction in men and women of 55 years and over. Design. The Rotterdam Study is a population-based prospective cohort study. In total 2453 men and 3553 women of 55 years and older were included in this study. The mean duration of follow-up was 4 years. Main outcome measures. Relative risks were estimated with Cox's proportional- hazard analysis. Cholesterol was analysed as a continuous variable and in sex-specific quartiles. Results. In subjects aged 55 years and older the relative risk of myocardial infarction was 1.9 in men (95% confidence interval 1.1-3.3) and 3.2 in women (1.5-6.4) in the highest compared to the lowest serum total cholesterol quartile (Q4 vs. Q1). In men and women of 70 years and older, total cholesterol remained an important risk factor for myocardial infarction (Q4 vs. Q1 relative risk 3.2; 1.3-7.7 and 2.9; 1.3- 6.6, respectively). For HDL cholesterol, the relative risk in the highest compared to the lowest quartile (Q4 vs. Q1) was 0.5 in men (0.3-0.9) and 0.4 in women (0.2-0.9). HDL cholesterol was a weaker predictor in men after the age of 70 (Q4 vs. Q1 0.8; 0.3-2.1). In women of 70 years and older the relative risk was also not significant (Q4 vs. Q1 0.6; 0.3-1.3), although the trend over the quartiles was still significant. Conclusion. Serum total cholesterol remains an important risk factor for myocardial infarction in men and women aged 70 years and older, whilst HDL cholesterol at older age remains important in women only

Distribution of echocardiographic parameters and their associations with cardiovascular risk factors in the Rotterdam Study

Insight into echocardiographic parameters in the general population may facilitate early recognition of ventricular dysfunction, reducing the population morbidity and mortality of heart failure. We examined the distribution of structural, systolic and diastolic echocardiographic parameters and their associations with cardiovascular risk factors in the Rotterdam Study, a population-based cohort study in men and women aged ≥55 years. Participants with prevalent heart failure, myocardial infarction and atrial fibrillation and flutter were excluded. Echocardiographic parameters were assessed using two-dimensional, M-mode and Doppler echocardiography. Echocardiograms were available in 4,425 participants. Structural parameters were generally larger in men, and most consistently associated with age, body mass index and blood pressure in both sexes. Prevalence of moderate or poor left ventricular systolic function was 3.9% in men and 2.1% in women. Age, body mass index and blood pressure were most consistently associated with systolic function. E/A ratio was lower in women than in men. Age and diastolic blood pressure were most consistently associated with E/A ratio in both sexes. In conclusion, ventricular systolic and diastolic dysfunction is present in asymptomatic individuals. Selected established cardiovascular risk factors are associated with structural, systolic and diastolic parameters