Following the recent recognition of the SU(3) and O(6) boson-fermion symmetries in the W and Pt regions, it is shown that a simple Hamiltonian can be constructed for the intervening transitional region. The proposed approach represents an extension of the consistent-$Q$ formalism, previously used in the description of even-even nuclei, and its predictions are discussed and compared with the low-lying structure in the odd-mass Os nuclei.

The evolution of Rayleigh-Bénard convection patterns has been studied quantitatively with use of digital image processing methods to measure the time dependence of the wave-vector field. The relative importance of wave-number variations, roll curvature, defects, and sidewalls was determined, with the Swift-Hohenberg model as a framework for analysis. Deviations from the model become pronounced for $\frac{(R-R_c)}{R_c}>2\mathrm{}$, where $R_c$ is the critical Rayleigh number.

Digitally processed shadowgraph images revealed time-dependent flow patterns slightly above the convective onset in a cylindrical cell of aspect ratio $L\equiv \frac{D}{2d}=15.0\mathrm{}$ ($D$ is diameter, $d$ is height). This time dependence was monitored for up to 200 horizontal thermal diffusion times. At larger Rayleigh numbers, the system reached time-dependent states after much shorter transients.

Electromagnetic emission from strong beam-plasma experiments displays scaling with the beam-instability growth rate ${\gamma }_b$. We relate this to the underlying turbulence through a simple model balancing rates of electrostatic energy transfer from the beam to the plasma. A transition from subsonic to supersonic turbulence appears as a break in the scaling of emitted power with ${\gamma }_b$. The implied values of the electrostatic-wave energy density obtained by measurement of the scattering of the relativistic beam agree qualitatively with the model, and yield $W\equiv \frac{E^2}{4\pi \mathrm{nkT}}\cong 0.01 \mathrm{to} 1$. The scattering waves apparently have phase velocities near the beam velocity.

It is shown here that Bevir and Grey's ac helicity-injection current-generation scheme does not depend on Taylor's relaxation principle. Instead, ac helicity injection is identified as the beating of a compressional Alfvén mode with a resistive diffusion mode to produce a surface current. This has the interesting consequence that the mode frequencies can be much higher than Taylor relaxation would allow. Although Taylor's principle is not needed to generate the surface current, it is required for the current to diffuse into the plasma because it is also shown that the current will not diffuse in classically.

An electron in the field of a high-frequency longitudinal wave experiences both Doppler-shifted intensity-gradient and phase-gradient ponderomotive forces. It is shown that Landau damping can be considered as a phase-gradient force effect. By taking the wave amplitude space dependence into account, we demonstrate another collisionless effect due to the intensity-gradient force. Either damping or amplification of the wave can occur depending on whether the electron density increases or decreases.

Diffuse critical neutron-scattering experiments in ${\mathrm{Ce}}_{1-x}{(\mathrm{L}\mathrm{a},\mathrm{Y})}_x\mathrm{Sb}$ ($x=0.1, 0.2$) reveal a fundamental new fluctuation behavior at the onset of magnetic ordering. Two different kinds of short-range-ordered quasistatic spin fluctuations coexist and strongly influence the order of the transition. The unusual fluctuation behavior is the result of competing bilinear exchange and quadrupolar interactions. A simple mean-field model indicates that the phase transitions are close to a multicritical point.

We have developed and applied a computer algorithm that generates realistic random-network models of $a$-Si with periodic boundary conditions. These are the first models to have correlation functions that show no serious discrepancy with experiment. The algorithm provides a much-needed systematic approach to model construction that can be used to generate models of a large class of amorphous materials.

In irreversible aggregation processes without a gelation transition the cluster size distribution approaches a scaling form, $c_k\mathrm{}\left(t\right)\mathrm{}\sim s^{-2\mathrm{}}\phi \left(\frac{k}{s}\right)$. Usking Smoluchowski's coagulation equation we determine the exponents in the mean cluster size $s\left(t\right)\mathrm{}\sim t^z$ ($t\to \infty$) and in the small- and large-$x$ behavior of the scaling function $\phi \mathrm{}\left(x\right)\mathrm{}$. Depending on certain characteristics of the coagulation coefficients, $\phi \mathrm{}\left(x\right)\mathrm{}\sim x^{-\tau }$ ($x\to 0$) or $\phi \mathrm{}\left(x\right)\mathrm{}\sim \exp (-x^{\mu })$ ($x\to 0$) with $\mu$ some negative constant. In aggregation processes with gelation a similar scaling form is obtained as $t$ approaches the gel point.

Calculations of the change in pressure and magnetostriction which are exact to second order in the polarization are presented. From these effects it is possible to extract a combination of the linear field dependence of the Landau parameters and effective masses from a thermodynamic measurement in the normal phase of a Fermi liquid.

Evidence that melting in alkali halides may be caused by shear instability of the solid is obtained by comparison of observed liquid structure, as determined by previously published neutron-scattering data and molecular-dynamics calculations, with that expected from an analysis of the structural changes associated with the shear instability.

We have studied the marked transparency to zero sound observed in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$A$ over a broad range of temperature. This nonlinear effect is induced by sound excitation levels small in comparison with the condensation energy. It is attributed to the creation by Cooper pair breaking of a nonequilibrium distribution of quasiparticles localized over a small region of the Fermi surface and relaxing toward equilibrium at a rate typical of normal processes.

We determine the aspect-ratio dependence of the critical percolation threshold for various systems of rods. An exact expansion, due to Coniglio et al., tests the conjecture that the threshold is proportional to the inverse of the expected excluded volume. We confirm the conjecture, and show that the proportionality becomes equality, for isotropic rods in three dimensions, in the slender-rod limit. In this limit, the critical region in which nonclassical exponents are valid vanishes.

We show that there are two regimes of irreversible, kinetic aggregation of aqueous colloids, determined by the short-range interparticle potential, through its control of the sticking probability upon approach of two particles. Each regime has different rate-limiting physics, aggregation dynamics, and cluster-mass distributions, and results in clusters with different fractal dimensions. These results set limits on the fractal dimension, $d_f$, for gold aggregates of $1.75<~d_f<~2.05$ (±0.05).

Branched polymers, the formation of which is controlled by a finite monomer supply or by termination, are studied with a Monte Carlo simulation. The radius-mass dependence of the two models (in dimension from 2 to 8) is unequal, showing that branched polymers in toto cannot be identified with "animals." Study of the growth of mass with time helps to interpret the result.

The excess energy or enthalpy in thermodynamically unstable solutions relaxing towards equilibrium is related to properties of the cluster distribution. We thus infer a general scaling Ansatz and the simultaneous occurrence of two mechanisms during the system evolution, both in agreement with data. We also find two different classes of phase points, and propose a graphical method to analyze these matters in microcalorimetric measurements.

A new kind of dipole-active surface vibrational resonance has been observed on (110) surfaces of Cu and Ni by electron-energy-loss spectroscopy. An analysis based on lattice dynamics suggests that such resonances should be observable on surfaces where a single bulk-phonon dispersion relation has a pseudo band gap in the probed phonon density of states. In the [110] direction of facecentered-cubic metals this gap is due to the particular geometric structure in that direction.

By use of x-ray-diffraction and electrochemical techniques we have measured the phase diagram of the pseudoternary solid, ${\mathrm{Li}}_x{\mathrm{Cu}}_y{\mathrm{Mo}}_6{\mathrm{S}}_8$. We compare our measurements of the Li chemical potential, $\mu$, and the response function $-{\left(\frac{\partial x}{\partial \mu }\right)}_{y,T}$ near phase boundaries to predictions of theory.

We observe clear evidence for formation of a field-induced two-phase state in ${\mathrm{Br}}_2$-intercalated graphite. This is the first time such an effect has been seen in a two-dimensional system, and the sharpness of the features is quite extraordinary. We also observe possible manifestations of domain-wall dynamics in the two-phase regime.

We present helium metastable-quenching spectra of K/Ni(111) whose spectral features show unusual coverage dependence. These are explained by a mechanism in which the surface ionizes the incident singlet ${\mathrm{He}}^{*}$ and then neutralizes the ion to form a ${\mathrm{He}}^{*}$ triplet. These spectra reflect the fact that the local work function varies strongly along the surface.