The shape and area of the output from physically realizable amplifiers of inverted $Q\left(2\right)\mathrm{}$-degenerate two-level atoms are calculated analytically. The ($4\pi -\delta$)- or $\delta$-pulse output is made up from a sequence of $\pm 4\pi$ double-humped pulses followed by $\pm (4\mathrm{}\pi -2\mathrm{}\delta )$ pulses, where $\delta =2\mathrm{}invcos(-\frac{1}{4})$.

The general qualities of a type of thermodynamic engine that depends intrinsically for its operation on irreversible processes are set forth and demonstrated experimentally in the context of a thermoacoustic heat-pumping engine.

The transport effects induced by resistive ballooning modes are estimated from a theory, and are found to be mainly thermal electron conduction losses. An expression for electron thermal diffusivity ${\chi }_e$ is derived. The theoretical predictions agree well with experimental values of ${\chi }_e$ obtained from power balance for the ISX-$B$ plasmas at high poloidal beta.

By adding an $l=2\mathrm{}$ stellarator field to a betatron accelerator, a new configuration is obtained which is capable of accelerating multikiloamp beams and which will tolerate a large (more than 50%) mismatch between the particle energy and the vertical magnetic field. The additional field is a twisted quadrupole which acts as a strong-focusing system. This device has been analyzed both analytically and numerically.

The epitaxial growth of Au on Pd(111) was studied by ion scattering/channeling, low-energy electron diffraction, and Auger analysis. A sharp transition from the pseudomorphic state to the state with misfit dislocations and strain was found. The critical thickness is 2.0±0.2 Å in this layer-by-layer growth system. The Au coverage dependence of the lattice constants for substrate and overlayer were measured in detail.

Measurements of the dynamics of phase separation in homogeneous mixtures of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ have been performed at temperatures ranging from 17 mK to within 3 mK of the tricritical temperature. The results are the first to show the expected critical slowing down of the dynamics proportional to $\epsilon$ as the tricritical point is approached.

The thermal diffuse background between diffracted electron beams has been analyzed with high-energy resolution. The main contribution arises from a surface phonon single-scattering event. The surface phonon dispersion is measured along the $\overline{\Gamma }-\overline{X}$ direction, and compared with theoretical models.

Measurements of the frequency shift, $\Delta f_1$, and the damping, $\Delta f_2$, of a vibrating wire in a saturated ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ solution are reported. A transition is observed in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ quasiparticle Fermi gas from a hydrodynamic regime at 10 mK to a collisionless-excitation gas regime at the lowest temperatures, < 0.3 mK, where the mean free path becomes extremely long. The comparison between $\Delta f_1$ and $\Delta f_2$ supports the slip theory of Højgaard Jensen et al. with the recent modification proposed by Carless, Hall, and Hook.

High-resolution angle-resolved photoemission measurements on the $\mathrm{sp}$ surface state on Cu(111) show that its peak width increases on approaching the Fermi energy, a result contrary to usual expectations based on final-state lifetimes. The effect is explained in terms of inherent energy and/or momentum broadening of the surface-state wave function.

Susceptibility and remanence as well as the phonon thermal conductivity ${\kappa }^{\mathrm{ph}}$ are studied as a function of temperature and magnetic field on amorphous spin-glasses ${\mathrm{}\left(\mathrm{PdCuSi}\right)\mathrm{}}_{90}$T${\mathrm{M}}_{10}$, TM=Mn, Fe, Co. For the Fe and Co alloys ${\kappa }^{\mathrm{ph}}\mathrm{}\left(T\right)\mathrm{}$ is enhanced in a field of 5 T below $T_g$. The results give evidence for thermal activation of cluster moments (magnetic two-level systems) by inelastic scattering of phonons, coupled via spin-orbit interaction to the magnetic two-level systems. Contributions of spin-wave-like excitations to ${\kappa }^{\mathrm{ph}}(T, H)$ cannot be detected.

Pristine 98% ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$-enriched cis-polyacetylene has been investigated by electron-nuclear double-resonance spectroscopy at temperatures between 77 and 300 K. Spectra are characterized by two and only two ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ hyperfine tensors. The relative magnitudes and symmetry of the tensor elements established that the paramagnetic electron resides in a delocalized $\pi$ orbital. Experimental results indicate that the delocalized electron is constrained to a potential well of approximately 100 Å width.

ESR measurements of a CuMn spin-glass performed as a function of frequency and magnetic field angle confirm that there is a mode splitting as predicted by the triad model. At large field angles neither the triad nor vector models are consistent with the data for any assignment of anisotropy constants, suggestive of a breakdown in the assumption of a rigid spin rotation. However, at 180° the data are well described by a vector model. Determinations of the anisotropy constants by various experimental methods are discussed.

${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$ NMR has been used to probe the volume-dependent static and dynamic spin susceptibility of expanded liquid cesium. Data taken over the temperature range 55-1400°C cover the density range $1.03<\mathrm{}\rho <1.92\mathrm{}$ g ${\mathrm{cm}}^{-3\mathrm{}}$. For $\rho \lesssim 1.5$ g ${\mathrm{cm}}^{-3\mathrm{}}$, both the isobaric temperature dependence and the isothermal pressure dependence of the Knight shift change sign and the spin susceptibility becomes increasingly enhanced. Analysis of the nuclear relaxation rates at low densities indicates changes in the $q$-dependent susceptibility suggestive of a metallic antiferromagnet above its ordering temperature.

The resonant character of magnetic field damping by moving magnetic monopoles allows the field to survive indefinitely when the monopole plasma frequency is sufficiently large, even if the field is immersed in a conducting plasma. Dynamo growth of galactic field can still occur on time scales ∼${10}^7$-${10}^8$ yr in the presence of a halo composed of monopoles. A linear stability analysis suggests that a monopole's mass is $m\sim {10}^{18}$ GeV/${\mathit{c}}^2$ and that the monopoles should have an anisotropic flux ∼1 ${\mathrm{m}}^{-2\mathrm{}}$ ${\mathrm{yr}}^{-1\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$.

Pattern selection is discussed in regard to a situation where a stable, nonuniform state of a nonlinear dissipative system propagates into an initially unstable, homogeneous region. The velocity of the propagating front and the wavelength of the pattern formed behind the front are determined by a marginal-stability criterion. The special system studied here has a Lyapunov functional, but the periodic state which propagates is not the one which minimizes the functional.

A large class of broken supersymmetry theories is shown to imply the existence of fermions ${\lambda }^{\pm }$ and ${\lambda }^0$, lighter than or nearly degenerate with the $W^{\pm }$ and $Z^0$ gauge bosons, and with vanishing baryon and lepton number. If the ${\lambda }^{\pm }$ is appreciably lighter than the $W^{\pm }$ it can be readily produced in $W^{\pm }$ decay, as well as in $e^{+}-e^{-}$ collisions.

The new data on charged-particle inclusive cross sections obtained by the TASSO and MARK II detectors in the $e^{+}{e}^{-}$ annihilation process are analyzed in the framework of perturbative QCD. In the leading logarithmic order there results $\Lambda =0.9-1.5\mathrm{}$ GeV for the scale parameter, but this reduces to $\Lambda =0.4-0.6\mathrm{}$ GeV if the higher-order correction in the $\overline{\mathrm{MS}}$ scheme is included. The obtained value of ${\Lambda }_{\overline{\mathrm{MS}}}$ is slightly larger than but still consistent with that determined from the data of deep-inelastic electron and neutrino scatterings.

At zero temperature SU(2) and SU(3) gauge theories confine quarks and spontaneously break chiral symmetry. At some nonzero temperatures $T_c$ ($T_F$) these gauge theories lose confinement (chiral symmetry breaking). The order of these phase transitions and the relation between $T_c$ and $T_F$ have been studied with use of simulation methods which neglect internal fermion loops. For SU(2) both transitions are second order and $1<~\frac{T_F}{T_c}<1.30\mathrm{}$. For SU(3) the transitions are first order and $1<~\frac{T_F}{T_c}<~1.05$, with $T_c\approx 200$ MeV.

The ground-state energy density $E_0$ is examined for a wide class of two-dimensional supersymmetric quantum field theories by use of a strong-coupling lattice expansion. It is shown that regardless of how the lattice expansion is defined (there are many ways to put the fermions on the lattice) $E_0\to 0$ in the continuum limit.

The backward differential cross section for ${\pi }^{-}-d$ elastic scattering has been measured at incident momenta between 420 and 1160 MeV/c. The data show two bumps at around 670 and 1100 MeV/c, two dips near 630 and 980 MeV/c, and a break at 550 MeV/c. The result of a phenonomenological fit is consistent with the existence of three dibaryon resonances in this energy region. A theoretical calculation of Kanai et al. agrees well with the data below 800 MeV/c, but the agreement becomes worse above 800 MeV/c.