Two new results are reported: (1) verification of the finite-interaction-length threshold for stimulated Brillouin scattering in a plasma with no critical layers, and (2) use of the time-dependent Stark effect to detect ion-frequency electric fields in a plasma.

The diffusion coefficient of suspended Brownian particles diverges near a hydrodynamicregime transition point.

An experimental analysis is made of the scattering of microwaves by the density fluctuations due to the current-driven ion-wave instability in a toroidal plasma confinement device, the FM-1 spherator. It is found that the instability exists in the collisional regime and it is inhibited (i.e., quenched by two order of magnitude) in the trapped-electron (i.e., banana) regime. The inhibition occurs when the electron collision frequency is about equal to the electron bounce frequency between mirror trapping.

A new saturation mechanism for the nonlinear stage of parametric decay instabilities arises from pump-induced cross-correlations between Fourier modes. These correlations result in a renormalization—usually a reduction—of the mode coupling coefficients. Coupling saturation arises from the same order of approximation as the familiar induced-scattering nonlinearity. When applied to the $2{\omega }_{\mathrm{pe}}$ decay instability and the electron-ion decay instability, coupling saturation greatly reduces the turbulent wave energy compared to earlier calculations.

Neutron-scattering studies of the quasi-one-dimensional conductor ${\mathrm{K}}_2$Pt${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_4$${\mathrm{Br}}_{0.30}$·${\mathrm{H}}_2$O demonstrate not only the existence of soft phonon modes but also the coexistence of central peaks and the development of a superlattice on cooling which, however, never becomes a true structural phase transition. We suggest that the central peak is due to bromine-induced, static, platinum-chain distortion and show that it affects the electronic motion sufficiently to create a strong enough fluctuation in the three-dimensional system to remove the expected phase transition.

The direct transmission of transverse zero sound between two $\mathrm{AC}$-cut quartz transducers is observed in the vicinity of 3 mK; at higher temperatures the transition to classical viscous shear-wave behavior is observed through the effect on the damping of a single transducer.

The pressure dependence of the reflectivity of trigonal and amorphous Se has been measured between 1.1 and 4.5 eV using a new technique. The results indicate that local-field corrections are large. Structure near 2 eV suggests a localized excitation in both the amorphous and the crystalline material.

The complex asymmetric critical scattering observed in quasielastic neutron scattering measurements in K${\mathrm{D}}_2$P${\mathrm{O}}_4$ is explained as arising from the piezoelectric coupling between the acoustic waves and the ferroelectric fluctuations. Detailed calculations give good agreement with the available measurements. It is further proposed that this coupling provides a way of determining the atomic motions in the ferroelectric fluctuations and also leads to a change in the critical properties of these and related materials.

Measurements have been performed of the dependence on scattering angle and target orientation of the oscillatory structure recently observed in low-energy ion scattering from surfaces. Wide variation is exhibited in the behavior of oscillation maxima as a function of scattering angle depending on the target species studied. A semiquantitative model is presented which treats the phenomenon in terms of quantum mechanical phase interference between pairs of near-resonant quasimolecular levels.

The separate contributions of the TTF and TCNQ chains to the total magnetic susceptibility of TTF-TCNQ are evaluated from measurements of the gyromagnetic ratio and EPR linewidth. From the temperature dependence of these susceptibilities, we show that the metal-insulator transition at 54°K affects primarily the TCNQ chain. The TTF chain is primarily affected by the transition at 38°K and dominates the conductivity in the semiconducting regime.

The usual stimulus-based neural counting model for audition is found to be mathematically identical to the well-know semiclassical formalism for photon counting. In particular, we explicitly demonstrate the equivalence of McGill's noncentral negative binomial distribution and Peřina's multimode confluent hypergeometric distribution for a coherent signal imbedded in chaotic noise. Dead-time corrections, important both in neural counting and in photon counting, are incorporated in a generalized form of this distribution. Some specific implications of these results are discussed.

In 1918, Lense and Thirring calculated that a moon orbiting a rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect to 1% with two counter-orbiting drag-free satellites in polar earth orbit. In addition to tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken near the poles. New geophysical information is inherent in the polar data.

Direct evidence is presented for final- (and/or initial-) state interaction effects in 18 GeV/c $\mathrm{pd}$ reactions involving inclusive $\gamma$ and $V^0$ production. This evidence is manifested as an excessive number of protonlike events as compared to the number of neutronlike events; an asymmetric distribution in center-of-mass longitudinal $V^0$ momentum for the protonlike events; and strong spectator-proton production-angle asymmetry correlated with high-momentum spectators.

A tendency for the ${\pi }^{-}$ to peak at small negative rapidity in the center-of-mass system for the reaction $K^{+}+p\to {\pi }^{-}+X$ at 100 GeV may be related to a difference in the momentum spectra for the strange quark and the nonstrange quark in the $K^{+}$ meson, as may anomalies in the average multiplicity of charged particles and in the ${p_T}^{max}$ of events as a function of ${\pi }^{-}$ rapidity.

A neutrino-proton scattering experiment has been performed at Fermilab using a wide-band horn-focused neutrino beam and the 15-ft bubble chamber filled with hydrogen. For the inclusive reaction ${\nu }_{\mu }+p\to {\mu }^{-}+\mathrm{hadrons}$, the mean value of $Q^2$ is found to increase linearly with energy as is expected from Bjorken scaling and a fit to the data gives $〈Q^2〉=(0.18\mathrm{}\pm 0.01)E$. The distribution in the Bjorken scaling variable $x$ shows evidence for deviations from predictions based on electron-scattering data and the quark-parton model.

The inclusive cross sections, measured up to large values of effective mass ($\equiv \frac{q^2}{2\nu }$), are well fitted by $\frac{d\sigma }{d^{3}p}=B_x\exp (-\frac{{\alpha }_x{p}^2}{2m_x})$. Values of $B_x$ and ${\alpha }_x$ are given for Be, C, Cu, and Ta at the incident proton energy of 600 MeV and for Ag, Ta, and Pt at 800 MeV. Extremely large $\frac{d}{p}$ and $\frac{t}{p}$ ratios and large $A$ and $q^2$ dependences of the relative cross sections are observed.

Gauge symmetry admits a local unit isovector and leads to the magnetic monopoles in Weinberg's unified theory. I predict ${sin}^2\theta =\frac{1}{2}$ for the mixing angle $\theta$ on the basis of Dirac's condition for charge quantization. This interesting result should be tested experimentally.

A confined magnetic flux solution of finite length and finite energy, arising from non-Abelian-gauge theory, is presented.

I extend the Bloch-Nordsieck idea to show that in the lowest nontrivial order of radiative correction the fermion-fermion and gauge-meson-fermion scattering rates are finite, provided that they are averaged over the initial and summed over the final internal spin states. Questions of the physical gauge coupling and infrared slavery are discussed.

The differential cross section as a function of energy has been carefully measured and analyzed for the ground and first three excited states in the reaction ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}(d, {}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$. The results show no evidence for rearrangement effects. Finite-range, distorted-wave Born-approximation calculations, which are necessary to fit the data, yield spectroscopic factors about 0.6 of those expected on the basis of an ${\left(f_{\frac{7}{2}}\right)}^3$ description of ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$ and a conventional ($d$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) normalization.