Saturation studies of the E-beam sustained discharge atomic xenon laser

In an electron beam sustained discharge xenon laser the discharge energy deposition has been varied in order to investigate the saturation effect on the xenon laser. The current density of the electron beam is varied separately in the range of 0.1-2.7 A/cm2 to obtain optimized discharge excitation conditions as a function of electron beam current density and gas pressure. An optimal fractional ionization f=3.5-4×10-5 is found, independent of the electron beam parameters. The synergy of electron beam and discharge excitation has resulted in a maximum specific energy of 15 J/l at a total gas pressure of 9 ba

IR Recombination Lasers

The present study contributes to a better understanding of the atomic Xe laser as a powerful IR source. Several important phenomena like the dependence of both the observed optimized input power and maximum output power on the square of the gas density and also the constant fractional ionization are reported and verified theoretically. The insight in the kinetics of this system has also lead to the realization of small-size continuous systems with output powers in the range of watts. The results of the present study can be used to predict the performance of the atomic Xe laser under different operating conditions

Fermi and intramode relaxation phenomena in CO2lasers

Using a 1 ns pulse from a short-pulse CO2laser system, the evolution of the gain in a TEA system was studied during and after amplification. This resulted in a very direct observation of a few relaxation processes. We estimated the effective intramode relaxation rate constant to be larger than6 times 10^{6}torr-1/s. The Fermi relaxation time constant was found to be 30 ± 7 ns at 760 torr. We conclude that for nanosecond pulse amplification, intramode relaxation cannot be neglected

Intrinsic efficiency and critical power deposition in the e-beam sustained Ar:Xe laser

Experimental investigations on an e-beam sustained near infrared Ar:Xe laser have been carried out to determine the intrinsic efficiency at optimized conditions. A parametric study at different sustainer currents reveals a maximum output energy depending on current density. Up to 8 bar the optimized laser output power per unit volume increases linearly with 1.1MW/1 bar. Intrinsic efficiencies of up to about 8% are feasible

Risk profiles and prognosis of treated and untreated hypertensive men and women in a population-based longitudinal study: the Reykjavik Study

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldThe aim was to examine the risk profiles and prognosis of treated and untreated hypertensive subjects and examine to what degree confounding by indication was present in a population-based cohort study with up to 30-year follow-up. The study population consisted of 9328 men and 10 062 women, aged 33-87 years at the time of attendance from 1967 to 1996. The main outcome measures were myocardial infarction (MI), cardiovascular disease (CVD) mortality and all-cause mortality. Comparing the risk profiles between treated and untreated subjects entering the study showed significantly higher values for some risk factors for treated subjects. During the first 10 years, hypertensive men without treatment, compared with those treated, had a significantly lower risk of suffering MI, CVD and all-cause mortality, hazard ratio (HR) 0.72 (95% CI; 0.57, 0.90), 0.75 (95% CI; 0.59, 0.95) and 0.81 (95% CI; 0.61, 0.98), respectively. No significant differences in outcome were seen during the following 20 years. In identically defined groups of women, no significant differences in mortality were seen between groups. Subgroup analysis, at two stages of the study 5 years apart, revealed that some cardiovascular risk factors had a higher prevalence in hypertensive men who were treated at the later stage, compared with those who remained untreated (P=0.004). In conclusion, hypertensive treated men had a worse prognosis during the first 10 years of follow-up than untreated ones, which is most likely due to worse baseline risk profile. Hypertensive men that were treated at a later stage had a worse risk profile than those not treated at a later stage

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