The relevance of a high-temperature mechanism for vacancy migration, the double jump, has been established by molecular dynamics in Al and Na. Migration energies for single jumps are 0.42 ± 0.1 eV and 0.12 ± 0.02 eV, respectively, while for double jumps they are about five times larger. Second-near-neighbor jumps are found in Na near melting. Comparison with lattice statics and experiments indicates the adequacy of a monovacancy description. The inclusion of double jumps explains the anomalous diffusion of Na at high temperature.

Negative transverse magnetoresistance was observed in quantized accumulation layers on the ($000\overline{1}$) face of ZnO single crystals. The results are interpreted in terms of surface scattering center with giant magnetic moments, possibly due to the formation of charged clusters. Good quantitative agreement is found between theory and experiment.

The core levels and the valence-band region of CeN have been studied by x-ray photoemission. Clear evidence is found that Ce has a mixed valence between 3 and 4 in this compound. A comparison of the $4d$ spectra of the Ce pnictides and of pure Ce at different temperatures leads to the conclusion that the $\alpha$ phase of this metal corresponds very likely to an intermediate valence.

We have observed luminescence lines from "hot" free excitons and from recombination of "hot" electrons within electron-hole droplets in Ge under uniform $〈111〉$ uniaxial stress. Our results suggest that both "hot" and "cold" electrons coexist in the same electron-hole droplets. We have also measured the total lifetime of the hot electrons, which is in good agreement with intervalley relaxation by electron-electron scattering.

A detailed quantitative study of the low-temperature spin-wave dynamics has been made for the classical Heisenberg-coupled chain using computer simulation. Results for the relaxation rates are presented and compared with dynamic scaling and other predictions.

This Letter presents a quantum scattering theory of electron stimulated desorption and applies it to recent observations of ion angular distributions. The Franck-Condon desorption cross section is calculated in a three-dimensional reflection approximation. It is shown that the adsorption models suggested by Madey, Czyzewski, and Yates, which attribute anisotropy in the angular distributions to initial-state effects, are consistent with the theory and the data.

We have performed heat-pulse experiments which graphically demonstrate the strong effect of the phonon wind in propelling electron-hole drops. Investigation of the dynamics of droplet motion sheds light on the mechanisms of propulsion and damping.

In the variational approach to scattering, one traditionally adopts a trial function of the form ${\mathcal{I}}_t\mathrm{}\left(r\right)={\Sigma }_i{C}_i{\varphi }_i+j_l\mathrm{}\left(r\right)+{\lambda }_{t}g\left(r\right)\mathrm{}{n}_l\mathrm{}\left(r\right),$ where the ${\varphi }_i$ are square-integrable functions, ${\lambda }_t$ is the tangent of the trial phase shift, $j_l\mathrm{}\left(r\right)\mathrm{}$ and $n_l\mathrm{}\left(r\right)\mathrm{}$ are, respectively, the regular and irregular Riccati-Bessel functions, and $g\left(r\right)\mathrm{}$ cuts $n_l\mathrm{}\left(r\right)\mathrm{}$ off at the origin. A modified form for the trial function is suggested and used in the determination of phase shifts in the static-exchange hydrogen problem.

I review arguments indicating that there is no real, physically detectable, local inertial-induction effect in general relativity, contrary to recent comments by Tittle.

I discuss the mixing of states containing heavy quarks with new quantum numbers. The mixing of the new states can be substantial in gauge theories with right-handed currents, even though direct neutral couplings conserve all flavors. Some experimental implications of the results are discussed.

We have measured the invariant cross section for inclusive $\varphi$ production in proton-nucleus collisions at 400 GeV/c near Feynman $x=0\mathrm{}$. For transverse momenta in the range between 0.8 and 3.5 GeV/c the ratio of $\varphi$ to ${\pi }^{-}$ rises from 1 to 7%. We also report on correlations with particles opposite the $\varphi$ in the center-of-mass system as they relate to the Okubo-Zweig-Iizuka rule.

Angularly integrated cross sections for the reaction ${}_{}{}^7{}_{}{}^{}\mathrm{Li}({\pi }^{+}, {\pi }^0){}_{}{}^7{}_{}{}^{}\mathrm{Be}_{}^{*}{}_{}{}^{}$ (429 keV) were measured over the energy range of 90 to 210 MeV by a selective "prompt-$\gamma$" detection method. These results, combined with the summed cross sections to the ground state and excited state, yield the cross section for the ground state alone. The excitation function for the excited state is flat with cross sections of about 0.3 mb. For the ground-state transition the cross sections are between 1.2 and 1.9 mb. The data are compared with theoretical calculations.

Excitation-function data have been analyzed for the reactions (${}_{}{}^4{}_{}{}^{}\mathrm{He}$, $\mathrm{xn}$) with targets ${}_{}{}^{233,234,235}{}_{}{}^{}\mathrm{U}$ and ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$. Values of the neutron emission probability $G_n$ have been extracted by comparing reaction couples ($4n-3n$), ($3n-2n$), and ($2n-1n$) leading to the same final products. The values of $G_n$ for ${}_{}{}^{238}{}_{}{}^{}\mathrm{Pu}$ vary from 0.3 at 12 MeV to 0.1 at 20 MeV to 0.5 at 35 MeV. Similar trends are found for ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ and ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$. Statistical-model calculations give a similar but weaker trend.

We have measured the angular distributions of the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$)${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ in the c.m. energy range 12.22 to 15.07 MeV. The data and analysis, indicate a broad (${\Gamma }_1\simeq 650$ keV) $L=8\mathrm{}$ resonancelike structure centered at $E_1\simeq 13.15$ MeV. The severe damping of the $L=8\mathrm{}$ structure of the angular distribution and the deep minimum in the integrated cross section at $E_2\simeq 13.7$ MeV appear to be due to interference between the broad resonance at $E_1$ and a narrow (${\Gamma }_2\simeq 100$ keV) $L=8\mathrm{}$ resonance at $E_2$. This interpretation is consistent with two-level $R$-matrix fits.

We have observed transitions between Rydberg states of He with sub-Doppler resolution, using a novel technique. Ordinary Doppler line shapes, observed at low magnetic fields, are completely altered at high fields by the quadratic Stark effect induced by velocity-dependent electric fields arising from atomic motion transverse to the magnetic field. The high-field line shape has an abrupt cutoff, corresponding to $v_{\perp }\simeq 0$ atoms, whose slope is primarily limited by the homogeneous linewidth.

A fundamentally new method is proposed for eliminating first-order Doppler broadening from atomic or molecular transitions which can be tuned by means of electric or magnetic fields. This method employs crossed electric and magnetic fields; it does not require molecular beams or counter-propagating laser radiation. Possible applications to atomic and molecular spectroscopy are discussed.

The soliton formation with its detuning of the resonance is shown to be an important saturation mechanism for the two-plasmon decay instability at the quarter critical density in laser-irradiated plasmas.

A differential rotation of a collisionless $\theta$-pinch column during implosion has been observed and explained by a model in which the driving mechanism is the off-diagonal element $p_{r\theta }$ of the pressure tensor. Rotational motion was detected by directional probes and spectroscopic techniques. Experimental data were modeled by a one-dimensional hybrid code which included ionization and charge exchange of protons with neutral H atoms.

We present the first experimental evidence for the existence of turbulent temperature fluctuations in plasmas. These measurements were accomplished by a spectral analysis of blackbody electron cyclotron emission. The fractional fluctuation in the mean electron energy is up to 10% for typical Princeton Large Tokamak discharges. The spectrum of temperature turbulence extends well beyond the electron diamagnetic-drift frequency $f_{*}$ and shows no resemblance to the simultaneously existing turbulent density fluctuations.

It is shown that an almost loss-free mode of motion for a straight screw dislocation exists in a three-dimensional lattice. Thus dislocations can move at velocities of the order of half the speed of sound at stress levels corresponding to a strain $s<\mathrm{}{10}^{-3\mathrm{}}$, even in the presence of a much higher static Peierls stress. A strain of this magnitude can be provided by lattice vibrations, so that the dislocation-phonon complex moves in a solitonlike mode, requiring no external stress.