It is shown that a magnetic perturbation may lead to an enhanced transport of heat and particles. The observation of anomalous electron heat conduction and particle diffusion in the experimental devices may be explained by the effect.

A study has been made of the motion of isotopic impurities in solid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The tunneling frequency of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ atoms with neighboring ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ atoms in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ lattice has been deduced from nuclear magnetic relaxation measurements. The volume variation of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ tunneling rate is much greater than that of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^3{}_{}{}^{}\mathrm{He}$ tunneling rate (exchange).

We report a new luminescence in GaP, which is attributed to a gallium vacancy complexed with an oxygen donor. We discuss evidence for this assignment and the roles of various radiative and nonradiative nearest neighbor complexes, which are created by replacement of the Ga vacancy with different impurities.

A theory of inelastic electron tunneling due to phonons in normal metal-insulator-metal junctions is developed based on a multichannel tunneling model. The results are in good agreement with experiment and show that shifts in the bulk phonon energies observed by inelastic tunneling arise largely from kinematical factors. The observed harmonics are shown to arise due to two-phonon processes involving phonons at both sides of the barrier. A phonon polarization selection rule is shown to be operative in such tunneling processes. The model presented in this paper can readily be generalized to other types of inelastic excitations observed in tunnel junctions.

We present a new method for obtaining interband energies to high accuracy from electroreflectance spectra taken under general experimental conditions. The method does not require optical constants or a Kramers-Kronig analysis; hence it is particularly suitable for new materials such as chalcopyrites, binary alloys, and amorphous semiconductors.

Line emission above the direct interband threshold is observed at 77°K in $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x:\mathrm{N}$ for $x=0.19\mathrm{} \mathrm{and} 0.21$. This emission is identified with a sharp resonance state of the N isoelectronic trap. This state owes its existence both to the attractive short-range nature of the trap potential and to the details of the energy-band structure of $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$.

Using x-ray scattering, we have made the first observations of the spectrum of acousto-electrically amplified phonons in the quantum limit, where the conduction-electron system obeys quantum statistics and the observed phonon wave vector $q$ is comparable to the electron Fermi wave vector $k_{\mathrm{F}}$. In GaAs samples with degenerate carrier distributions, we observe a dramatic quantum anomaly consisting of an abrupt decrease in phonon gain for $q$ larger than $2k_{\mathrm{F}}$.

Experimental limits have been set on the intensity of a branching in the ${\beta }^{+}$ decay of the the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}$ ground state to the 1838-keV $0^{+}$ state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$, providing an upper limit on the departure from isospin purity in the $A=42\mathrm{}$ system. The limits are branching ratio < 4.6 × ${10}^{-4\mathrm{}}$ with 95% confidence; branching ratio < 1.2 × ${10}^{-4\mathrm{}}$ with 50% confidence.

For an $N\ne Z$ system interacting through a Hamiltonian including the Coulomb interaction, the effect of proton-neutron correlations on the ground state and its isobaric analog is discussed. It is shown that the correlation greatly reduces the isospin impurity in the ground state.

The violation of the normal parity rule in ($\alpha ,{\alpha }^{\prime }$) scattering is related to a velocity dependence in a purely central, spin-independent $\alpha -N$ force. The distorted-wave Born-approximation formalism of the process is presented, and the specific case of the $3^{+}$ state in ${\mathrm{Ni}}^{58}$ is calculated in the plane-wave Born approximation. The role of the velocity dependence is discussed in physical terms, and a formal similarity with Weber's old theory of electromagnetism is found.

An error in the application of Kepler's law vitiates the claim of Hegyi and Curott to have measured a helium abundance in $\mu$ Cas $A$ significantly low in terms of cosmological theories. The accuracy required for a significant result is probably unattainable at this time.

We give an estimate, based on nonrelativistic quantum mechanics, of the thermal contribution to the Lamb shift in the blackbody approximation. We show that observable corrections may exist.

The Goldreich-Schubert thermally driven turbulence extending to the deep interiors of solar-type stars which exhibit rotational slowing is precluded by spectroscopic observations showing the presence of lithium and beryllium. These observations, similar observations of the sun, the solar-wind torque, and the solar oblateness are consistent with a model for which such a turbulence is terminated at the surface of a rapidly rotating core containing 95% of the star's mass.

The nuclear reactions between ${\mathrm{C}}^{12}$ and ${\mathrm{O}}^{16}$ are shown to be vitally important during explosive oxygen burning because they regulate the number of $\alpha$ particles produced per ${\mathrm{Si}}^{28}$ nucleus. Since it appears that explosive oxygen burning produces the observed abundances of the nuclei between ${\mathrm{Si}}^{28}$ and ${\mathrm{Ca}}^{42}$, the value of the ${\mathrm{C}}^{12}$ + ${\mathrm{O}}^{16}$ total reaction cross section will help determine the nature of the explosions that have produced the elements.

The differential cross sections for ${\pi }^{-}p$ elastic scattering over the angular range 155° to 177° in the center of mass have been measured at 33 incident-pion momenta in the range 600 to 1280 MeV/c. Angular distributions are presented. The extrapolated differential cross sections at 180° show considerable structure, in particular a dip near 1150 MeV/c. In general the near-180° cross sections do not agree with existing phase shift solutions above 1000 MeV/c

We have measured the reactions ${\pi }^{\pm }p\to {\pi }^{\pm }p$ and ${\pi }^{+}p\to K^{+}{\Sigma }^{+}$ at 5.0 GeV/c in the region $2.2<-t<\mathrm{}3.5\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. We find the minimum cross section of the dip at $-t=2.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ in ${\pi }^{+}p$ elastic scattering to be 0.16 ± 0.05 ${\mathrm{\mu }\mathrm{b}/\mathrm{G}\mathrm{e}\mathrm{V}}^2$. The ${\pi }^{-}p$ differential cross section exhibits similar structure, while the ${\pi }^{+}p\to K^{+}{\Sigma }^{+}$ channel shows a steady decline in cross section as $\mathrm{}\left|t\right|\mathrm{}$ increases. The polarization of the ${\Sigma }^{+}$ remains large and positive to at least $-t=2.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

A semiclassical theory of the mobility of excess electrons in gaseous He is given. The electron-He interaction is treated via an effective Wigner-Seitz potential. Departures of the mobility from classical kinetic theory are explained by two mechanisms: first, scattering of electrons from fluctuations in the effective potential, and second, formation of low-mobility localized states in deep potential wells. Two parameters are introduced in the theory, and by adjusting them we get good agreement with the experimental values of Levine and Sanders.

A very large growth rate, large saturation amplitude, hard-onset flute mode in a multipolelike magnetic field is suppressed by a factor of 60 in power by negative current feedback to the plasma. Upon suppression of the instability, the center-line density increased 7%. The required feedback gain and phase are in rough agreement with a linear slab-model theory.

Particle motion in magnetohydrodynamically stable magnetic mirrors and in the high-frequency electric fields characteristic of the collective modes of such a system is shown to be restricted by two simple constraints. These constraints, which reduce to the usual magnetic moment and kinetic energy in the absence of fluctuating fields, dictate that while even small-amplitude waves induce large magnetic-moment excursions, the particle-containment properties of the trap are not greatly reduced by the fluctuations.

We describe "undulation spectra" in the luminescence of the isoelectronic trap N in GaP codoped with shallow acceptors. These novel spectra are shown to arise from an interference effect in the wave functions of electrons, arising from coherently scattering potentials due to pairs of N traps and neutral acceptors. The general phenomenon can occur in any indirect band-gap material.