High-resolution incoherent neutron spectroscopy has, for the first time, been applied to aqueous solutions and has demonstrated unambiguously the existence of a second zone of weakly interacting water molecules around two divalent cations ${\mathrm{Ni}}^{2+}$ and ${\mathrm{Mg}}^{2+}$.

Measurements of the size of holes burned in the frequency spectrum of a heat current in ${\mathrm{Al}}_2$${\mathrm{O}}_3$ by resonant phonon scattering show that the holes decay when they leave the region containing the scattering centers in distances which indicate that the crystal surface scattering is largely inelastic at 200 GHz and 2 K. The hole is monitored by observation of the scattering produced by a second ionic species tuned to the same frequency.

The upper demixing critical point in carbon disulfide + nitromethane bounded by a crown glass surface which is expected to preferentially adsorb nitromethane has been studied. The $\sigma$-polarized reflectivity of the liquid/glass interface rises sharply with decreasing temperature above the bulk critical temperature. This effect cannot be explained as a purely bulk phenomenon, but agrees well with an approximate version of the critical wall-layer theory of de Gennes and Fisher.

Competing ferromagnetic and antiferromagnetic interactions are studied in hierarchical Ising models, which are exactly solvable with nonclassical phase transitions at finite temperature. As model parameters are changed to increase frustration, a spin-glass phase is entered with chaotic renormalization-group trajectories. At successively longer distances, strong and weak spin correlations are encountered in a chaotic sequence. A microscopic description of a spin-glass emerges, with noncontiguous spins mutually pinned within distinct infinite subsets.

It is proposed that the 100-TeV threshold for the appearance of anomalies in cosmic-ray interactions is associated with the critical energy of about 60 GeV/nucleon center-of-mass energy for phase transition to quark matter in nucleus-nucleus interactions. This proposal implies that the high-energy primary spectrum contains a significant heavy nuclear component (e.g., Fe).

Theory and experiment are compared for the energy-energy correlation function in the reaction $e^{+}+e^{-}\to A+B+X$, with hadrons $A$ and $B$ nearly back to back. This correlation function is sensitive to the transverse-momentum transfers incurred in quark decay.

The $\mathrm{qq}\overline{\mathrm{qq}}$ system has been examined by solving the four-particle Schrödinger equation variationally. The main findings are that (1) $\mathrm{qq}\overline{\mathrm{qq}}$ bound states normally do not exist, (2) the cryptoexotic $0^{++}$ sector of this system with $K\overline{K}$ quantum numbers is probably the only exception to (1) and its bound states can be identified with the $S^{*}$ and $\delta$ just below $K\overline{K}$ threshold, (3) $\mathrm{qq}\overline{\mathrm{qq}}$ bound states provide a model for the weak binding and color-singlet clustering observed in nuclei, and (4) there is no indication that this system has strong resonances.

Light, colored scalars are shown to preserve all presently observed short-distance properties of quantum chromodynamics even when belonging to large multiplets of $\mathrm{SU}{\mathrm{}\left(3\right)\mathrm{}}_c$. However, light-scalar pair production by gluon fusion dominates hadronic high-$p_T$ single-particle inclusive production cross sections at $\overline{p}p$ collider energies ($\sqrt{s}=540\mathrm{}$ GeV) and two-jet production even at $\sqrt{s}\approx 50-60$ GeV. Embedding in a unified SU(5) theory requires many scalars to be superheavy in order to preserve asymptotic freedom below the unification mass.

It is shown that an expansion of interacting-boson-approximation wave functions for deformed nuclei in an SU(3) basis leads to a simple interpretation of intrinsic excitations and $E2\mathrm{}$ transitions and that it is possible to express these results in terms of a single, empirical parameter. Effective $\Delta K=0\mathrm{} \mathrm{and} 2$ matrix elements can also be extracted. The former is shown to be the dominant mode of SU(3)-symmetry breaking, leading to a natural explanation for the empirical behavior of $\beta$ and $\gamma$ vibrations.

The structure of nuclei at very high spins can be studied by measuring correlations between $\gamma$-ray energies in the unresolved spectrum emitted. Collective rotations have been shown to produce characteristic features in such correlation spectra. The features produced by the noncollective alignment effects in some high spin Er nuclei are shown here.

The solution of Dirac-type equations by the linear expansion technique suffers from variational instability due to difficulties in obtaining accurate matrix representations of the $\overrightarrow{\alpha }·\overrightarrow{\mathrm{p}}$ operator in conventional basis sets. A new matrix representation of $\overrightarrow{\alpha }·\overrightarrow{\mathrm{p}}$ is proposed which resolves the problem. The method has been successfully applied in numerical calculations.

With use of the FAST 2D laser-shell model, the acceleration of a 20-μm-thick plastic foil up to 160 km/s has been simulated. It is possible to follow the Rayleigh-Taylor bubble-and-spike development far into the nonlinear regime and beyond the point of foil fragmentation. Strong shear flow develops which evolves into the Kelvin-Helmholtz instability. The Kelvin-Helmholtz instability causes the tips of the spikes to widen and as a result reduce their rate of "fall."

The simple neoclassical nonresonant-point model of Hedrick et al. is slightly modified by leaving the ion transport unspecified (since it is now known to be resonant). Small continuous changes in the microwave power/neutral density can cause hysteresis and catastrophe jumps in the equilibria, in qualitative agreement with experiment.

It is shown that the incommensurate transverse ordering in tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) is governed by two nonlinearly coupled continuous fields. The equations which determine the stationary configurations of the two fields are nonintegrable and have erratic and periodic solutions. The periodic solutions contain a set of separatrices which correspond to the topological barriers appearing in the sliding temperature range. These barriers between locally stable states may explain the hysteresis observed in neutron-scattering measurements.

The homogeneous linewidth is calculated for resonant optical transitions in glasses. The width is due to modulation of the optical levels caused by coupling to the diagonal as well as off-diagonal elements of the two-level modes. The main contribution arises from diagonal modulation of abundant but weakly coupled two-level modes. For a flat density of states of two-level modes and a dipole-quadrupole coupling a large $T^{1.75}$ behavior is found in good agreement with recent data.

It is shown that fractional charges of solitons in charge-density-wave systems can be measured directly by studying frequency-dependent currents. The nonlinear conductivity and the associated "noise" frequencies in Nb${\mathrm{Se}}_3$ are interpreted within this picture. Solitons with charge $e^{*}=\frac{e}{2}$ are expected. An analysis of existing experiments yields $e^{*}=0.3e-0.4e$.

The magnetism of Fe and Ni is investigated by a cluster theory with two novel features: (i) The coupling of magnetic moments formed by clusters (described by a local band theory) is determined, thus incorporating short-range order as well as collective modes. (ii) The clusters are coupled by source and sink terms describing transport processes. The results indicate that Fe is closer to a local moment system, whereas Ni seems to be a prototype for a local band theory.

The conductance of a disordered system of finite volume $L^d$ ($d$ spatial dimensions) is calculated by making use of a recently developed self-consistent theory. Scaling equations are derived for the dimensionless conductance $g$ and the scaling function $\beta \mathrm{}\left(g\right(L\left)\right)=\frac{d\ln g}{d\ln L}$ is explicitly calculated for arbitrary dimension $d$. It is shown that the theory obeys scaling in the sense of Wegner, Thouless, and Abrahams et al.

The dynamics of classical ferromagnetic Heisenberg chains in a magnetic field is investigated. Contrary to previous theories, in the longitudinal spectral shapes temperature is found to play a crucial role through a dynamical spin-energy coupling whose effect is competitive with the field. Thermal disorder ultimately causes a nearly isotropic situation, leading to a new interpretation of the features of recent computer experiments.

There is presently a discrepancy between the theoretical and the experimental determinations of the purely quantum electrodynamic decay rate for orthopositronium. This Letter presents the first exact calculation of any contribution to the decay rate of orthopositronium to order ${\alpha }^7$.