Resistance fluctations in submicrometer narrow Si inversion layers are studied over a wide range of temperatures and electron concentrations. Thermally activated switching on and off of discrete resistance increments is observed, caused by the capture and emission of individual electrons at strategically located scatterers (interface traps). The traps have a broad distribution of activation energies, as assumed in accounting for $\frac{1}{f}$ noise in larger devices.

The question of the energy dissipation in the computational process is considered. Contrary to previous studies, dissipation is found to be an integral part of computation. A complementarity is suggested between systems that are describable in thermodynamic terms and systems that can be used for computation.

Gamma rays following the reaction ${}_{}{}^{162}{}_{}{}^{}\mathrm{Dy}({}_{}{}^3{}_{}{}^{}\mathrm{He},\alpha )$ have been studied as a function of excitation energies in ${}_{}{}^{161}{}_{}{}^{}\mathrm{Dy}$. For excitation energies above ∼3 MeV a (2.2±0.2)-MeV bump appears in the $\gamma$-ray spectra. It is suggested that the bump originates from enhanced $\Delta \Omega =1\mathrm{}$ single-quasiparticle transitions.

The first measurement of pion double charge exchange at low energy is reported. The reaction ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}({\pi }^{+},{\pi }^{-}){}_{}{}^{14}{}_{}{}^{}\mathrm{O}$ was measured at an incident pion energy of 50 MeV. Differential cross sections of the double analog transition are given in the angular range 50°-120°. Strong nonanalog transitions were also observed.

The formation of ${\mathrm{Ar}}_n$ clusters in a supersonic expansion and their fragmentation by electron impact ionization is measured by analyzing the kinematically different behavior in a scattering experiment. The fragmentation of dimers and trimers is appreciable but depends only slightly on the electron energy.

The statistical distribution of the Stokes pulse energy is measured for transient stimulated Raman scattering in pressurized hydrogen gas. Large fluctuations of the Stokes energy obeying an exponential distribution law are observed. These macroscopic energy fluctuations are caused by quantum noise in the initial state of the system.

A new connection between autocorrelation and cross correlation functions of the intensities of signal and idler in parametric oscillators is derived, with the same origin and generality as the Manley-Rowe relations and with inserting experimental implications in the quantum domain.

Observations of persistent currents in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$ have been made with use of a recently developed ac gyroscope technique. The persistent currents are generated in a toroidal region filled with a fibrous material with average pore size of ${10}^{-2\mathrm{}}$ cm. In this geometry, a mean critical velocity of 7 × ${10}^{-2\mathrm{}}$ cm/sec was observed. To within experimental error, no decay of the currents was observed for periods of over one hour.

A resonance effect is observed between the wavelength of a planar-channeled ion beam and the layer period of a strained-layer superlattice. Catastrophic dechanneling is observed when the wavelength and layer period are matched. A phase-rotation analysis is developed to calculate the amount of dechanneling and the amount of strain in the superlattice.

The transmission coefficient between two terminals of a one-dimensional ring with arbitrary scatterers is calculated exactly as a function of enclosed magnetic flux, $\varphi$. At low temperatures, where the inelastic diffusion length is larger than the size of the ring, its conductance follows from the Landauer formula. Oscillations of the conductance as a function of the characteristics of the scatterers and of $\varphi$ (with a period ${\varphi }_0=\frac{\mathrm{hc}}{e}$) are found. The oscillations persist even when the elastic scattering is strong.

A magnetic phase transition ($T_M=0.53\mathrm{}$ K) to a long-period (∼${10}^2$-Å) magnetic state has been observed via neutron scattering in the superconductor ($T_c=5.6\mathrm{}$ K) Ho${\mathrm{Mo}}_6$${\mathrm{Se}}_8$. The characteristic wave vector $q_c$ is strongly temperature dependent even though no higher-order satellites are observed. With use of a Ginzburg-Landau model it is found that the temperature dependence of $q_c$ can be explained as due to a renormalization of the superconducting order parameter caused by the coupling to the local magnetization density.

The classical and the quantum mechanical descriptions of surface-state electrons which are perturbed by a periodic force $F\left(t\right)=e\epsilon \Sigma n^{} \delta \mathrm{}(t-nT)\mathrm{}$ are compared. The stochastic behavior which characterizes the classical treatment, and which is manifested by the energy diffusion and ionization rates, is suppressed by quantum effects.

Symmetry-forbidden phonon Raman scattering is used to investigate in situ the formation of GaAs-Ge heterojunctions. Under epitaxial growth conditions the band bending in GaAs induced by the first monolayers of Ge decreases strongly for thicker overlayers. For amorphous overlayers the Fermi level remains pinned around midgap. A simple model is presented which explains the observed behavior. The development of the Ge phonons demonstrates crystalline growth for substrate temperatures $T_g>~300$ K and amorphous growth for $T_g=100\mathrm{}$ K.

This paper presents extensive Monte Carlo simulations of the random-field Ising model in various dimensions for long times in moderately large systems, and specifically addresses the question of whether the lower critical dimension is 2 or 3. The authors find long-range order for $d=3\mathrm{}$ and no long-range order for $d=2\mathrm{}$. The marginality of the $d=2\mathrm{}$ case is further checked by studying a system in $d=\frac{\ln 8}{\ln 3}\approx 1.89$ dimensions simulated by a fractal; the authors thus conclude that the lower critical dimension is 2.

High-accuracy, long-time dc conductivity measurements were performed at fixed temperatures. The conductivity corresponding to a metastable state created by a quick heat treatment was found to be time dependent on the time domain of 10-${10}^5$ sec. A logarithmic expression describes the time dependence in the entire temperature range investigated ($100 \mathrm{K}<T<\mathrm{}150\mathrm{} \mathrm{K}$). A simple model, based on the analogy with spin-glasses, is proposed. The possible role of low-energy excitations and infrared divergences is also discussed.

Using a ferromagnetic solid as an array of spin-polarized atoms allows one to measure directly the spin dependence of electron scattering in core excitations. Strong spin polarization of the $3p\to 3d$ energy-loss electrons scattered from ferromagnetic ${\mathrm{Fe}}_{83}$${\mathrm{B}}_{17}$ has been observed. The large spin polarization in the autoionization emission satellite above the $\mathrm{MMM}$ Auger line is discussed.

The first observation of acoustomagnetic effects in solids by a superconducting quantum interference device (SQUID) is reported. In particular, novel SQUID-NAR (nuclear acoustic resonance) techniques have been used to measure spin-lattice relaxation times and to observe the cw NAR in tantalum metal between 1.58 and 4.2 K.

Resonant enhancement of photoemission cross sections for valence bands of Al-GaAs(110) surfaces has been observed in the vicinity of the Al $2p$ core-excitation threshold. The observation provides strong evidence for the existence of an Al $2p$ extrinsic surface core exciton which decays into single and double final hole states, resulting in two types of resonance. Features of these resonances are found to be drastically changed with Al coverage.

Starting from the large-$N$ power counting which suggests that the baryons are QCD solitons, the authors derive an exact large-$N$ equation identical to the so-called bootstrap condition of static strong-coupling theory. This equation determines the group structure of the baryon multiplets at $N\to \infty$. One solution is the standard nonrelativistic quark model.

The authors describe a search for supermassive, slowly moving magnetic monopoles, employing a single thick slab of naphthalene-doped acrylic scintillator. Slow, massive particles produce scintillation pulses of unusually long duration in the thick slab and can thus be distinguished from the large flux of relativistic muons that penetrate the detector at sea level. The current limit on the flux of monopoles is 4.1×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$ ($1\sigma$) for velocities $6\times {10}^{-4\mathrm{}}c\lesssim V<\mathrm{}2.1\mathrm{}\times {10}^{-3\mathrm{}}c$.