Abnormal Audibility Zones in Long Distance Propagation through the Atmosphere

1949 ◽  
Vol 21 (1) ◽  
pp. 6-16 ◽  
Author(s):  
Everett F. Cox
Keyword(s):  
Long Distance ◽  
Distance Propagation

Computation of long-distance propagation of impulses elicited by Poisson-process stimulation

1995 ◽  
Vol 74 (6) ◽  
pp. 2415-2426 ◽  
Author(s):  
K. Moradmand ◽  
M. D. Goldfinger
Keyword(s):  
Poisson Process ◽  
Conduction Velocity ◽  
Interspike Interval ◽  
Short Interval ◽  
Propagation Distance ◽  
Long Distance ◽  
Small Constant ◽  
Current Spread ◽  
Distance Propagation ◽  
Impulse Train

1. The purpose of this work was to determine whether computed temporally coded axonal information generated by Poisson process stimulation were modified during long-distance propagation, as originally suggested by S. A. George. Propagated impulses were computed with the use of the Hodgkin-Huxley equations and cable theory to simulate excitation and current spread in 100-microns-diam unmyelinated axons, whose total length was 8.1 cm (25 lambda) or 101.4 cm (312.5 lambda). Differential equations were solved numerically, with the use of trapezoidal integration over small, constant electrotonic and temporal steps (0.125 lambda and 1.0 microsecond, respectively). 2. Using dual-pulse stimulation, we confirmed that for interstimulus intervals between 5 and 11 ms, the conduction velocity of the second of a short-interval pair of impulses was slower than that of the first impulse. Further, with sufficiently long propagation distance, the second impulse's conduction velocity increased steadily and eventually approached that of the first impulse. This effect caused a spatially varying interspike interval: as propagation proceeded, the interspike interval increased and eventually approached stabilization. 3. With Poisson stimulation, the peak amplitude of propagating action potentials varied with interspike interval durations between 5 and 11 ms. Such amplitude attenuation was caused by the incomplete relaxation of parameters n (macroscopic K-conductance activation) and h (macroscopic Na-conductance inactivation) during the interspike period. 4. The stochastic properties of the impulse train became less Poisson-like with propagation distance. In cases of propagation over 99.4 cm, the impulse trains developed marked periodicities in Interevent Interval Distribution and Expectation Density function because of the axially modulated transformation of interspike intervals. 5. Despite these changes in impulse train parameters, the arithmetic value of the mean interspike interval did not change as a function of propagation distance. This work showed that in theory, whereas the pattern of Poisson-like impulse codes was modified during long-distance propagation, their mean rate was conserved.

Influence of the ocean-bottom structure in the long-distance propagation by seismic survey source

2016 ◽  
Vol 140 (4) ◽  
pp. 3021-3021
Author(s):  
Toshio Tsuchiya ◽  
Shinpei Gotoh ◽  
Yukino Hirai ◽  
Etsuro Shimizu
Keyword(s):  
Seismic Survey ◽  
Ocean Bottom ◽  
Long Distance ◽  
Distance Propagation
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