Studies of large scale unstable growth formed during GaAs(001) homoepitaxy

Atomic force and scanning tunneling microscopy studies have been performed on GaAs(001) films grown by molecular beam epitaxy. Multilayered mounds are seen to evolve when the growth conditions favor island nucleation. As the epilayer thickness is increased, these features grow in all dimensions but the angle of inclination remains approximately constant at 1°. The mounding does not occur on surfaces grown in step-flow. We propose that the multi-layered features are due to an unstable growth mode which relies on island nucleation and the presence of a step edge barrier.     

Chromosomal aberrations resulting from UV exposures to G1 Xenopus cells

Abstract— The dose dependence of chromosomal aberration frequencies induced by UV light in G₁Xenopus cells has been examined. Total aberration frequencies did not exceed control levels until a dose of approximately 7.5 Jm^-2 was administered. Chromatid type aberrations were prevalent throughout the dose range 7.5–25.0 Jm^-2. Chromosome type aberration frequencies were comparatively low but exceeded control levels throughout the range 10.0–25.0 Jm^-2, Results of supporting experiments suggested that most of the chromosome type aberrations observed were in the second mitosis following exposures and were derived from aberrations which normally appear as chromatid types at the first mitosis following exposures.     

Isotope dynamic mixing and vibronic structure

Existing theories which deal with the isotope dependence of vibronic structure have neglected the isotope dependence of vibration dynamics. The latter dependence (isotope dynamic mixing) is an adiabatic correction to vibronic structure theory. A theory of vibronic structure, which includes isotope dynamic mixing, is developed. The results of model calculations are presented.