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Presents a study that examined the transitions in the spectra of as-grown gallium arsenide/aluminum-gallium arsenide quantum wells using piezoreflectance. Methodology; Comparison of the piezoreflectance and photoreflectance of the samples; Determination of the transition energies from the pizeoreflectance.

Presents a study that measured the in-well ambipolar diffusion coefficients and carrier lifetimes in ordered all-binary quantum wells composed of indium-arsenic-gallium arsenide short-period strained-layer superlattices (SPSLS) grown on gallium arsenide substrates. Use of picosecond optically induced transient grating and pump-probe techniques; Exhibition of a higher in-plane hole mobilities of quantum wells containing SPSLS.

Presents a study which investigated the optical properties of high quality In[subx[Ga[sub1] - [subx]As/GaAs single quantum wells. Theoretical considerations; Experimental techniques in molecular beam epitaxial growth; Results of measurements on the photoluminescence spectra from single quantum wells.

The piezoreflectance technique has been used to optically characterize resonant tunneling structures that utilize isolated single quantum wells. The heavy- and light-hole transitions associated with the quantum wells were prominent in the spectra of samples with barrier widths ranging from 50 to 34 Å. Their spectral positions depended not only on quantum well and barrier thicknesses, but also significantly on the amount of carrier confinement produced by barrier height. Furthermore, variations in the magnitude of impurity transitions could be observed in the spectra of different samples. [ABSTRACT FROM AUTHOR]

In a series of 411 consecutive carotid endarterectomies 29 patients were identified with vocal cord paralysis. All patients were symptomatic, although in many these symptoms were subtle and rapidly resolved. There was a statistically significant predominance of left-sided paralysis. Excluding three patients who died during the initial year of follow-up return of normal voice was noted in 22 patients, but complete return of vocal cord function was present in only 15. Apposition of the contralateral vocal cord against a paralyzed vocal cord allowed for production of normal voice in five patients. Less than 1% of patients remained with symptoms at one year following endarterectomy. We conclude that vocal cord paralysis is a common complication of carotid endarterectomy; the voice becomes an unreliable guide as to its resolution. We recommend laryngoscopic examination of all patients who undergo bilateral carotid endarterectomy.