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Pulse wave velocity (PWV) was measured in situ in 11 isolated canine common carotid arteries. Seven arteries exhibited a linear PWV/pressure function at pressures ranging from 0 to 200 mm Hg. Four arteries yielded a linear relationship between PWV and pressure between 1 and 100 mm Hg; for these vessels the relationship was nonlinear at higher pressures. Seven arteries (five from the group which was linear up to 200 mm Hg and two from the group which was linear up to 100 mm Hg) were excised and presure/volume measurements were made in vivo. Using pressure/volume data, the Moens-Korteweg equation was evaluated as a predictor of the PWV/pressure relationship over the linear region. An expression was developed to anable prediction of the pressure/volume relationship using the coefficients at the linear PWV/pressure function; these predictions were evaluated. We found that, for this range, the Moens-Korteweg equation provides a very good basis for predicting the increase in PWV with increasing bias pressure. In addition, we found that the pressure/volume relationship of common carotid arteries is well represented by an exponential of the form V/V=Ke, which was derived as the inverse solution to the Moens-Korteweg equation. [ABSTRACT FROM AUTHOR]

A new method of evoked response detection, previously demonstrated in the ventricle, has been studied in the atrium at the time of routine pacemaker implant in 16 patients. The atrial evoked response was readily detectable in all patients due to excellent recovery from poststimulus polarization. In six patients, as experimental threshold-tracking pacemaker was used to automatically verify atrial capture and to generate strength-duration curves. It is concluded that this pacing technique is both simple and reliable, and that automatic atrial threshold tracking is feasible [ABSTRACT FROM AUTHOR]

Earlier work by the authors has shown that batch anaerobic digestionof waste milk and cattle slurry is feasible at COD loadings of up to293 kg COD m-3. Higher COD loadings were added to batch anaerobic digestion systems in an attempt to determine the maximum CODloading which could be applied without causing digester failure. Biogas methane concentration was found to give a good indication of the effect of the shock loading on the digestion system. COD removal was significantly reduced in digesters receiving the highest shock loading. Reduced NH4+- N and NH3 concentrations in this system suggested depressed biological activity. [ABSTRACT FROM AUTHOR]