Close parallels exist in Mössbauer-site signatures of ${\mathrm{Ge}}_{2\mathrm{-}2\mathrm{x}}$${\mathrm{Sn}}_{2\mathrm{x}}$${\mathrm{S}}_3$ glasses and crystalline alloys. The drastic loss of glass-forming tendency in this ternary for x≥0.62 correlates exactly with a change in molecular structure of corresponding crystals, thus favoring microcrystalline origin of glass formation.

We study the relaxation of thermally excited orientation fluctuations in a polymer nematic liquid crystal using photon correlation spectroscopy. The material studied is poly-γ-benzyl glutamate at a concentration just above the isotropic to nematic transition point. The relaxation rates of elastic deformation modes exhibit large anisotropies. Quantitative measurements of ratios of Frank elastic constants and Leslie viscosities are described.

The ultrasonic attenuation for a superconductor with generalized pairing is calculated via a scalar quasiparticle Boltzmann equation in the relaxation-time approximation, in the hydrodynamic limit. The attenuation follows a power law as a function of temperature T if the gap vanishes at points or lines on the Fermi surface. With an Anderson-Brinkman-Morel–type excitation spectrum, a ${\mathrm{T}}^2$ behavior is obtained for the sound attenuation, which is consistent with the recently measured attenuation for the heavy-fermion system ${\mathrm{UPt}}_3$.

We present the first NMR study of the quasi one-dimensional conductor ${\mathrm{Rb}}_{0.3}$${\mathrm{MoO}}_3$. From the line shape of the ${}_{}{}^{87}{}_{}{}^{}\mathrm{Rb}$ first-order quadrupole satellite, we have studied the onset of the incommensurate charge-density wave at $T_I$=184 K and the temperature dependence of the order parameter. Our results demonstrate the crucial role played by impurities both on the normal incommensurate and the incommensurate-commensurate transition and give evidence for an interaction between the charge-density wave and mobile defects around $T_I$.

If the Universe contains a nearly critical density of photinos which are also assumed to constitute the dark matter in our galactic halo, then gravitational trapping by the Sun and ensuing annihilation in the solar core yields a significant flux of ∼250-MeV neutrinos. This results in about 2 neutrino-induced events per kiloton-year in an underground proton-decay detector.

Monte Carlo Fourier path-integral techniques are explored. It is shown that fluctuation renormalization techniques provide an effective means for treating the effects of high-order Fourier contributions. The resulting formalism is rapidly convergent, is computationally convenient, and has potentially useful variational aspects.

Desorption has been induced on CsI by hydrogen clusters of mass ranging from 5 to 23. A cluster effect has been observed in comparison of the ${\mathrm{Cs}}^{+}$ desorption yields as obtained from intact and preexploded clusters. The variation of the yield with the sum of the electronic stopping powers of the cluster components (additive stopping) shows a fourth-power dependence. The contribution of collective effects in the interaction may play a crucial role in the nonlinearity of the process.

The local spin-density approximation in density-functional calculations of energy differences leads to some poorly understood departures from experiment, including excitation energies in atoms and binding energies in molecules. We show that errors in the exchange energy are a major source of these discrepancies. We identify classes of problems where local spin-density results should be satisfactory and others where they must be treated with caution. The consequences, particularly for the development of nonlocal modifications, are clear.

The time dependence of the magnetization of the dilute spin-glass Ag:Mn (2.6 and 4.1 at.%) prepared in the field-cooled state has been measured after the field has been cut off at a constant waiting time. The time dependence is found to be of the stretched exponential form, with a rate constant which varies exponentially with inverse temperature. This result appears consistent with an exponential distribution of independent, random free-energy levels in the spin-glass phase.

In superconducting filaments of cross sections smaller than about ${10}^{\mathrm{-}14}$ ${\mathrm{m}}^2$, in a large frequency range at all temperatures, collective density oscillations exist with a soundlike dispersion relation and weak damping. The restoring force is the Coulomb interaction. In the restricted geometry this force is proportional to the wavelength and hence does not shift the density mode to the bulk plasma frequency.

Steady-state and transient measurements of spin concentration have been carried out as a function of electrochemical charge injection in polypyrrole. A maximum of one spin per ∼10 pyrrole units has been observed for about 50% of the maximum charge. The data are interpreted in terms of quasiequilibrium polaron and bipolaron populations resulting from a two-step redox process. Surprisingly, it appears that at low doping levels, bipolaron formation is not favorable compared to formation of two polarons.

We develop the theory of oscillations of solar neutrinos as it applies to the electron recoil spectrum in ν-e scattering. The spectral information obtained by such measurements (as opposed to counting total event rates) is crucial for allowing observation of neutrino oscillations for masses down to 5×${10}^{\mathrm{-}7}$ eV. In this regard, we investigate effects of different masses and mixing angles, as well as such subtleties as thermal and pressure broadening, finite solar core size, and variable indices of refraction.

We present results of hydrodynamic calculations of iron core collapse and subsequent shock propagation using the 12${\mathrm{M}}_{\mathrm{cirdot}}$ and 15${\mathrm{M}}_{\mathrm{cirdot}}$ initial models of Woosley and Weaver. A softening of the equation of state of neutron-rich nuclear matter at high density and the effects of general relativity play a crucial role in generating successful, prompt explosions. The energy of the explosion varies from (∼1 to 3)×${10}^{51}$ ergs depending upon the degree of softness.

Near the onset of a period-doubling bifurcation, any dynamical system can be used to amplify perturbations near half the fundamental frequency: The closer the bifurcation point, the greater the amplification. An analytic expression for the frequency response curve is derived explicitly for the driven Duffing oscillator. Results of analog simulations are presented to check the main features of the theory. We propose that the superconducting Josephson parametric amplifier is an example of this amplification process.

The stroboscopic map of symmetric self-oscillators driven by pulses of alternating sign is constructed, for the regime of strong relaxation, by means of the so-called phase-transition curve. An ordering for the symmetries of the phase-locked orbits is found which is conjectured to be universal. Both results are illustrated by an exactly solvable example of such a system. When the approximation fails, unusual period doubling from symmetric orbits and strange attractors of two-dimensional structure are encountered.

I present the calculation of the effective Lagrangian from the σ quark model based on some reasonable assumptions of the spontaneously broken chiral symmetry, the large-${\mathrm{N}}_{\mathrm{c}}$ limit, and the nature of the effective action expansion. In addition to the Skyrme Lagrangian with a unique coupling constant e=π[2(3/${\mathrm{N}}_{\mathrm{c}}$${\left)\right]}^{1/2}$ and the Wess-Zumino term, it contains an extra new term (${\mathrm{N}}_{\mathrm{c}}$/96${\mathrm{\pi }}^2$) Tr (${\mathrm{\partial }}_{\mathrm{\mu }}$${\mathrm{L}}^{\mathrm{\mu }}$${)}^2$ which must be treated as a perturbative correction. This new term is responsible for the correct pion form factor corresponding to ${\mathrm{m}}_{\mathrm{\rho }}^2$=8${\mathrm{\pi }}^2$${\mathrm{f}}_{\mathrm{\pi }}^2$(3/${\mathrm{N}}_{\mathrm{c}}$ ). This model can be used to describe the rich low-energy dynamics of baryons and mesons with the unique mass scale ${\mathrm{f}}_{\mathrm{\pi }}$.

Elastic neutrino scattering off electrons in crystalline silicon at 1–10 mK results in measurable temperature changes in macroscopic amounts of material, even for low-energy (<0.41 MeV) pp ν’s from the sun. We propose new detectors for bolometric measurement of low-energy ν interactions, including coherent nuclear elastic scattering. A new and more sensitive search for oscillations of reactor antineutrinos is practical (∼100 Kg of Si), and would lay the groundwork for a more ambitious measurement of the spectrum pp, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ solar ν’s, and supernovae anywhere in our galaxy (∼10 tons of Si).

The Wolfenstein polarization observables $D_{\mathrm{NN}}$, $D_{S\Omega }$, and $D_{L\Omega }$, where Ω denotes a mixture of S and L polarization components, and the induced polarization P have been measured for the reaction pp→p${\pi }^{+}$n at 800 MeV, at geometries corresponding to ${\Delta }^{++}$ production from ∼10° to 80° in the center of mass. Comparisons are made to results from the model of Dubach, Kloet, and Silbar.

We show how some supersymmetric ${\mathrm{E}}_6$ grand unified theories, which may arise as the low-energy limit of superstring theory, provide a natural solution of the fine-tuning problem.

We have observed production of monochromatic low-energy photons in $e^{+}$$e^{\mathrm{-}}$ interactions between 10.6 and 11.2 GeV/$c^2$. We show that this signal is associated with the production of b-flavored meson pairs, and interpret it as due to the decay $B^{\mathrm{*}}$→B+γ. This is the first experimental evidence for the existence of vector bū or bd¯ bound states. We determine the mass difference of the vector and pseudo- scalar states, M($B^{\mathrm{*}}$)-M(B), to be 52±2±4 MeV.