An improved perfect-fluid energy-momentum tensor including spin and torsion is presented with use of a Lagrangian variational principle based upon the tetrad formalism of Halbwach and the method of constraints of Ray.

A two-dimensional $n$-component spin model with cubic or isotropic symmetry is mapped onto a solid-on-solid model. Subject to some plausible assumptions this leads to an analytic calculation of the critical point and some critical indices for $-2\mathrm{}<~n<~2$.

It is shown that the new interpretation of the scalar product in Hilbert space recently proposed by Aharanov, Albert, and Au is in fact the one underlying the stochastic phase-space formulation of nonrelativistic quantum mechanics. The extrapolation of this interpretation to the relativistic domain and its relationship to the program of geometrizing quantum theory and quantizing space-time are discussed.

A new symmetry-adapted perturbation theory is suggested with the following improved properties: The primitive function is localized, and for Coulomb potentials has only a single cusp; the modified equation has no spurious bound states. A systematic tight-binding perturbation expansion involving only two-center integrals is derived.

An orthogonalization process is proposed, applicable to spaces which are realizations of abstract Hilbert space. It is simpler than the Gram-Schmidt process. A recurrence relation which orthogonalizes a physical space is proposed and it is shown that the generalized Langevin equation is contained therein. This process serves as a basis for understanding the nature of the dynamic many-body formalism.

The nucleon magnetic moments are computed in lattice QCD in the quenched approximation with Monte Carlo techniques. As a by-product, the magnetic moment of the ${\Omega }^{-}$ is also calculated. It is found that ${\mu }_p=2.7\mathrm{}\pm 1.0$, ${\mu }_n=-1.6\mathrm{}\pm 0.5$, ${\mu }_{\Omega }=-1.7\mathrm{}\pm 0.6$, in nuclear magnetons, and $\frac{{\mu }_p}{{\mu }_n}=-1.6\mathrm{}\pm 0.2$.

It is shown that the strong isospin dependence observed in pion absorption on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ can be described by the two-body mechanism $\pi \mathrm{NN}\rightleftarrows \Delta N\rightleftarrows \mathrm{NN}$. The effect of the three-body mechanism is also calculated but found to be negligibly small. The $\Delta N\rightleftarrows \mathrm{NN}$ dynamics consistently determined from $\mathrm{NN}$ inelasticities is shown to be essential to understand the isospin dependence.

A self-consistent microscopic theory of synergic synchrotron-Cherenkov radiation is given in the framework of nonequilibrium statistical mechanics, and the power spectrum of the output radiation is calculated as a function of time. It is shown that the present results when taken in the asymptotic limit in time go over to those obtained by Schwinger, Tsai, and Erber.

A very accurate determination of the neutron coherent scattering length of natural uranium $b_{\mathrm{U}}$ was carried out with the neutron interferometer installed at the high-flux reactor of the Institut Laue-Langevin, Grenoble. A recently developed technique was used including the rotation of a parallel-sided Al phase shifter with and without the presence of the uranium sample in one path of the neutron beam. From the observed phase shift between the two interferograms the value $b_{\mathrm{U}}=8.417\mathrm{}\pm 0.005$ fm was obtained.

The first numerical determination of the thermodynamic isotropic-nematic transition in a simple three-dimensional model fluid, viz., a system of infinitely thin hard platelets, is reported. Thermodynamic properties were studied with use of the constant-pressure Monte Carlo method; Widom's particle-insertion method was used to measure the chemical potential. The phase diagram is found to differ considerably from predictions of a second-virial ("Onsager") theory. Virial coefficients up to the fifth were computed; $b_5$ is found to be negative.

The radiation emission from long and narrow Josephson tunnel junctions dc-current biased on zero-field steps has been ascribed to resonant motion of fluxons on the transmission line. Within this dynamic model a theoretical expression for the radiation linewidth is derived from a full statistical treatment of thermal fluctuations in the fluxon velocity. The result appears to be very general and is corroborated by experimental determination of linewidth and frequency of radiation emitted from overlap Nb-$I$-Pb junctions.

Modern, high-resolution neutron-scattering techniques, in particular neutron spin echo, were applied to reinvestigate the critical dynamics of iron at temperatures above the Curie point. It was found that previously claimed evidence for a crossover was in error, and that the dynamical scaling hypothesis unexpectedly breaks down at small wave numbers. This breakdown is shown to be due to spin-nonconserving forces, which are tentatively identified with the thermodynamic random fields.

The dynamical implications of the mean spherical approximation and related theories as they pertain to the electronic absorption spectra and to localized and delocalized electronic impurity excitations in liquids are discussed.

An analytic form for the structure factor of a fully aligned ferrofluid is presented. This model consists of spherical colloidal particles interacting through magnetic dipolar and attractive central potentials. The main feature of the method is the reduction of the problem to that of calculating the correlations in an isotropic fluid with the central interaction in rescaled form. The results show the particle chaining first proposed by de Gennes and Pincus.

The free energy stabilizing the Kondo singlet state is shown to be important in the total-energy and stability conditions for cerium and related solids. Explicit calculations are given for the simplest spin-½ Kondo model, using the relation to the Anderson Hamiltonian, which leads to a semiquantitative description of the $\gamma \to \alpha$ phase transition in cerium. The temperature dependence of the free energy has a universal form which can lead to a phase boundary terminating in two critical points.

The spectrum of density perturbations is calculated in the new-inflationary-universe scenario. The main source is the quantum fluctuations of the Higgs field, which lead to fluctuations in the time at which the false vacuum energy is released. The value of $\frac{\delta \rho }{\rho }$ on any given length scale $l$, at the time when the Hubble radius $\gg l$, is estimated. This quantity is nearly scale invariant (as desired), but is unfortunately about ${10}^5$ times too large.

Constraints on a hypothetical galactic halo of magnetic monopoles imposed by the galactic magnetic field are discussed. If the field is due to electric currents then a disk-stabilizing galactic monopole halo cannot exist unless the monopole mass $m_M\gtrsim {10}^{21}$ GeV, and then the monopole flux $F_M\lesssim 5\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$. However, if the galactic field is due to monopole charge-density fluctuations then a halo can exist provided $m_M\gtrsim {10}^{17}$ GeV and $F_M\lesssim 5\times {10}^{-11\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$.

The first experimental simulation of the tokamak divertor using a gaseous collector is presented. Significant results are as follows: (i) neutral gas at a pressure of a few militorr is sufficient to absorb the entire localized flux of plasma thermal energy and redistribute it over a wide area, (ii) elastic ion-neutral collisions constitute the main energy-absorbing process (at $T_{e,i}\lesssim 5$ eV), and (iii) a large pressure difference between divertor and main plasma chamber is maintained by plasma pumping in the connecting channel.

Measurements are presented of electron heating due to the resonance absorption of moderate-intensity ($\frac{v_0}{v_e}\lesssim 0.3$), $p$-polarized microwaves. The results agree very well with computer-simulation calculations and warm-wave-breaking theory. The experimental results are shown to scale to laser parameters.

This paper reports x-ray intensity analysis of the superlattice reflections associated with the order-disorder transition of di (tetramethyltetraselenafulvalenium) perrhenate [${\mathrm{}\left(\mathrm{TMTSF}\right)\mathrm{}}_2$Re${\mathrm{O}}_4$] at $T_c\simeq 180$ K. The results confirm the earlier proposed anion ordering and reveal large distortions of the anion array and of the TMTSF molecular stacks which are fairly well described by rigid displacements. Strong modulations of the overlap between TMTSF molecules along the stacks are clearly established and provide a key to the understanding of the metal-insulator transition observed at $T_c$.