In 24 median nerves from 12 healthy subjects, antidromic digital sensory potentials progressively diminished in size, averaging 40.4, 37.0, 30.7, and 23.9 microV X msec with stimulation at the palm, wrist, elbow, and axilla, respectively. In contrast, compound muscle action potentials changed minimally, measuring 19.4, 19.8, 19.0, and 18.2 mV X msec, respectively. Similar studies of the ulnar and radial nerves showed identical trends. Physiologic temporal dispersion can mimic conduction block of sensory nerves by summating the peaks of opposite polarity generated by fast- and slow-conducting axons. This type of cancellation affects muscle responses much less because motor unit potentials of longer duration superimpose nearly in phase, given the same latency shift as the sensory potentials.

Stimulation of the second (S1) or third (S2) digit elicits a median sensory potential at the wrist. Similarly, a shock applied to the median (Sm) or ulnar (Su) nerve at the wrist evokes a sensory potential of the fourth digit and a muscle potential over the thenar eminence. Hence, a concomitant application of S1 and S2 or Sm and Su with varying interstimulus intervals simulates the effect of desynchronized inputs. In 10 hands, a shift in latency on the order of 1 msec between S1 and S2 or Sm and Su caused a major reduction in sensory potential by as much as 30-40% but little change in muscle action potential. A latency difference slightly less than one-half the total duration of unit discharge maximized the phase cancellation between the two components and consequently the loss of area under the waveform.

We report on a Raman study of In1-x Ga x P over the whole range of alloy compositions, x. The additional peak, which appeared for x\lesssim0.98 and about which various interpretations have been proposed, is found to be constructed by two unresolved modes. The Raman spectra indicate that this alloy system has a modified two-mode behavior. The spectral half width of a TO mode broadened in the middle of the alloy composition. This is partly due to the strong two-acoustic-phonons scattering process.

The behavior of the densities of Si, SiF, and SiF2 radicals and SiF4 molecule were investigated for variations in electron density at pressure of 40 mTorr in a very high frequency (VHF) 60 MHz capacitively coupled plasma employing SiF4 gas. The SiF4 molecule was measured by infrared diode laser absorption spectroscopy, the SiF2 and SiF radicals were measured by laser-induced fluorescence, the Si atom was measured by ultraviolet absorption spectroscopy, and the F atom was measured by actinometric optical emission spectroscopy. The SiF4 density decreased with an increase in electron density, and the dissociation ratio of SiF4 was saturated to about 63% at electron densities of above 8.7×1010 cm−3. The SiF2 density decreased due to electron impact dissociation, whereas the F, Si, and SiF densities increased with an increase in electron density above 1.2×1011 cm−3. The total Si density was estimated to be of the order of 1010–1011 cm−3. Furthermore, the spatial distributions of SiF, SiF2, and SiF4 densities were investigated. They were almost flat inside the plasma region, but the SiF and SiF2 radicals decreased gradually outside the plasma region, and the SiF4 molecule increased. The behavior of the Si, SiF, and SiF2 radicals was in good agreement with the emission intensity of rare gases injected as trace gases. The kinetics of the species in VHF 60 MHz SiF4 plasma was clarified on the basis of the densities of the species and electrons measured. These experimental results are useful in predicting the radical densities of VHF SiF4 plasma using simulation.

In 20 radial nerves from 10 healthy persons, a referential derivation from the tip of the first or second digit registered two biphasic stationary peaks, PI-NI and PII-NII, following stimulation of the nerve in the forearm. These two peaks occurred slightly before the arrival of the propagating impulse at the wrist and at the base of the digit, respectively. With stepwise reduction of stimulation from a maximal to a threshold intensity, the far-field potential decreased in amplitude linearly with the near-field potential recorded at the junction of the volume conductor. Abduction of the first digit or flexion of the second and third digits altered the waveform and, to a lesser degree, the latency of the far-field peaks. However, these changes appeared in an inconsistent manner, which we were unable to characterize. We conclude that in far-field recording a stationary peak results at the border of the adjoining volume conductors in proportion to the magnitude of the propagating axonal volley approaching the boundary.