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  • 1
    ISSN: 1432-1971
    Keywords: Age ; Heart rate variability ; Spectral analysis ; Cholinergic ; Adrenergic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We compared heart rate variability measures of 11 normal children (4–12 years) to 23 normal adults (21–43 years) to study the effect of age on heart rate variability measures. Children had a significantly higher supine and standing heart rate and lower supine and standing systolic diastolic blood pressure. Children also had a significantly higher supine standard deviation of HR, supine low frequency (0.01–0.05 Hz) (p〈0.005), supine high frequency (0.2–0.5 Hz) (p〈0.001), and standing high frequency powers (p〈0.005) compared to adults. The ratio of mid frequency (0.07–0.15 Hz) to high frequency power (0.2–0.5 Hz) upon standing was significantly lower in children (p〈0.005). While there was a significant increase of the mid frequency power from supine to standing posture in the adult group (p〈0.02), there was no such significant increase in children. There were also significant negative correlations between age and supine low frequency, mid frequency, and high frequency powers, and standing high frequency power. These findings illustrate a decrease of cholinergic and an increase of adrenergic modulation of heart rate variability with age (4–43 years).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 31 (1991), S. 493-507 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A perturbation analysis is developed for 1-D shallow water flow over a curved bed for applications such as spillways. The perturbation approach leads to a new formulation of the problem with associated weak integral statement and approximation using finite elements. The flow may exhibit a hydraulic jump in the downstream regime. An artificial dissipation technique is introduced to stabilize the non-linear problem and suppress numerical oscillations. Numerical results demonstrate the performance of the model and compare it with the steep-slope shallow water formulation corresponding to the model with zero curvature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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