Wave propagation in alternating solid and viscous fluid layers: Size effects in attenuation and dispersion of fast and slow waves

1986 ◽  
Vol 48 (19) ◽  
pp. 1249-1251 ◽  
Author(s):  
Michael Schoenberg ◽  
Pabitra N. Sen
Keyword(s):  
Wave Propagation ◽  
Viscous Fluid ◽  
Size Effects ◽  
Slow Waves ◽  
Fluid Layers ◽  
Fast And Slow Waves ◽  
Attenuation And Dispersion

scholarly journals Abnormal gastric slow waves in patients with functional dyspepsia assessed by multichannel electrogastrography

2001 ◽  
Vol 280 (6) ◽  
pp. G1370-G1375 ◽  
Author(s):  
Xuemei Lin ◽  
Jiande Z. Chen
Keyword(s):  
Wave Propagation ◽  
Functional Dyspepsia ◽  
Slow Wave ◽  
Single Channel ◽  
Slow Waves ◽  
Lower Percentage ◽  
Healthy Controls ◽  
Fasting State ◽  
Gastric Slow Wave ◽  
Gastric Slow Waves

The aim of this study was to utilize multichannel electrogastrography to investigate whether patients with functional dyspepsia had impaired propagation or coordination of gastric slow waves in the fasting state compared with healthy controls. The study was performed in 10 patients with functional dyspepsia and 11 healthy subjects. Gastric myoelectrical activity was measured by using surface electrogastrography with a specially designed four-channel device. The study was performed for 30 min or more in the fasting state. Special computer programs were developed for the computation of the propagation and coupling of the gastric slow wave. It was found that, compared with the healthy controls, the patients showed a significantly lower percentage of slow wave propagation (58.0 ± 8.9 vs. 89.9 ± 2.6%, P < 0.002) and a significantly lower percentage of slow wave coupling (46.9 ± 4.4 vs. 61.5 ± 6.9%, P < 0.04). In addition, the patients showed inconsistencies in the frequency and regularity of the gastric slow wave among the four-channel electrogastrograms (EGGs). It was concluded that patients with functional dyspepsia have impaired slow wave propagation and coupling. Multichannel EGG has more information than single-channel EGG for the detection of gastric myoelectrical abnormalities.

Slow waves actively propagate at submucosal surface of circular layer in canine colon

1990 ◽  
Vol 259 (2) ◽  
pp. G258-G263 ◽  
Author(s):  
K. M. Sanders ◽  
R. Stevens ◽  
E. Burke ◽  
S. W. Ward
Keyword(s):  
Wave Propagation ◽  
Slow Wave ◽  
Proximal Colon ◽  
Slow Waves ◽  
Pacemaker Cells ◽  
Transverse Axis ◽  
Active Mechanism ◽  
Conduction Velocities ◽  
Circular Layer ◽  
Thin Band

Colonic slow waves originate from pacemaker cells along the submucosal surface of the circular layer in the dog proximal colon. These events propagate in a nonregenerative manner into the bulk of the circular layer. Conduction velocities consistent with an active mechanism for slow-wave propagation in the longitudinal and circumferential axes of the colon have been reported. Experiments were performed using intracellular recording techniques on canine colonic muscles to determine the regenerative pathway for slow-wave propagation. In a thin band of muscle adjacent to the submucosal border of the circular layer, slow-wave amplitude was independent of distance from a pacing source, and events propagated at a rate of approximately 17 mm/s in the long axis of the circular fibers and 6 mm/s in the transverse axis of the circular fibers. These findings suggest that slow waves propagate in a regenerative manner in this region. Slow waves decayed as they conducted through regions from which the pacemaker cells had been removed with space constants of a few millimeters. Thus the integrity of the thin pacemaker region along submucosal surface is critical for propagation of slow waves and the organization of motility into segmental contractions.

Myogenic regulation of propagation in gastric smooth muscle

1985 ◽  
Vol 248 (5) ◽  
pp. G512-G520 ◽  
Author(s):  
N. G. Publicover ◽  
K. M. Sanders
Keyword(s):  
Wave Propagation ◽  
Conduction Velocity ◽  
Circular Muscle ◽  
Slow Waves ◽  
Gastric Distension ◽  
Gastric Smooth Muscle ◽  
Conduction Velocities ◽  
Axis Parallel ◽  
Myogenic Regulation

Experiments were performed to test the effects of frequency and stretch on the velocity of slow wave propagation parallel and perpendicular to the long axis of circular muscle fibers in the canine gastric antrum. Slow waves were evoked from one corner of a rectangular sheet of muscle and propagated throughout the tissue. Mathematics were derived and are presented, which simultaneously compute conduction velocities in each direction, regardless of electrode positions. Increased rate of stimulation had no significant effect on conduction velocity in the circumferential axis, but propagation slowed in the axis perpendicular to the circular fibers by an average of 25% over interstimulus intervals between 12 and 60 s. Conduction velocity was also a function of the degree of stretch. The most rapid conduction velocity occurred when muscles were stretched to an average of 118% of the resting, fasted length found in situ in the axis parallel to the circular fibers and 140% in the axis perpendicular to the circular fibers. Propagation was blocked by stretching muscles past 200% of resting length. These results suggest that the frequency of slow waves and gastric distension are intrinsic mechanisms capable of regulating the spread of slow waves.

scholarly journals Inverse problems in cancellous bone: Estimation of the ultrasonic properties of fast and slow waves using Bayesian probability theory

2010 ◽  
Vol 128 (5) ◽  
pp. 2940-2948 ◽  
Author(s):  
Christian C. Anderson ◽  
Adam Q. Bauer ◽  
Mark R. Holland ◽  
Michal Pakula ◽  
Pascal Laugier ◽  
...  
Keyword(s):  
Probability Theory ◽  
Inverse Problems ◽  
Cancellous Bone ◽  
Slow Waves ◽  
Bayesian Probability ◽  
Ultrasonic Properties ◽  
Fast And Slow Waves
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