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The half-widths of five A III and two A IV lines have been measured in a pulsed arc operated in an argon-nitrogen mixture. Electron densities of 3.8 to 8.0 × 10 16 cm

The origin of heart rate variability (HRV) is largely in parasympathetic activity. The direct influence of sympathetic activity and other control mechanisms, especially at an increased HR, is not well understood. The objectives of the study were to investigate the influence of increasing HR on the properties of heartbeat interval (RR) series in young healthy subjects. ECG was recorded in 9 trained and 11 untrained young men during supine rest, standing, incremental running exercise and relaxation. During exercise, a breath-to-breath gas exchange was monitored. The RR time series analysis included the spectral analysis, detrended fluctuations analysis method and sample entropy (SampEn) calculation. During exercise, spectral powers were reduced dramatically in both groups. The dependence of short-term scaling exponent (alpha(1)) on the RR included a characteristic maximum, while SampEn for the same value of the RR had a minimum. The value of HR corresponding to the maximum of alpha(1) and minimum of SampEn (IHR) corresponded to the intrinsic HR obtained by an autonomic blockade. In trained subjects, the curves alpha(1) versus RR and SampEn versus RR were moved toward larger RR, compared with control. For HR values higher than IHR, alpha(1) decreased and SampEn increased. These results reveal that the complexity of the heart rhythm above intrinsic HR decreases with an increase in HR. We suggest that at the highest HR intrinsic heart control is reflected in the heart rhythm. We point out the possibility of developing a new non-invasive method for the determination of intrinsic HR from the curve alpha(1) versus RR.

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The Stark widths of 13 Ar III spectral lines have been measured at an electron density of 3.5 × 10 23 m −3 and electron temperature of 38 000 K in a linear pulsed arc plasma discharge containing an argon-helium mixture. The measured values were compared to the existing calculated values based on semiclassical and semiempirical approximations.

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Stark widths of three S III spectral lines belonging to 4p–5p transitions have been measured and calculated. Measurements have been performed in a low pressure linear pulsed arc at 2.1 × 1023 m−3 electron density and 40 000 K electron temperature. Calculations for S III lines were performed by using the modified semiempirical approach. For S IV 4s 2S–4p 2Po multiplet, calculations were performed within the semiclassical perturbation formalism. The obtained results were compared with other theoretical and experimental data.

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