Protein solution at appropriate pH and ionic strength has been shown to phase separate upon addition of suitable amount of anionic surfactant, sodium dodecylsulfate (SDS). We determine a series of cloud-point curves for bovine serum albumin-SDS complexes in aqueous solutions at different pH. Small angle neutron-scattering and light-scattering studies give strong evidence that these denatured proteins in solution are multicomponent polymerlike objects. We show that the generalized Flory-Huggins theory for polydisperse polymers can describe the cloud-point curves satisfactorily.

We present a phase diagram styrene in chemical equilibrium with polystyrene, in solution in cyclohexane. We observe an upper critical solution point. Within our experimental error, the polymerization line meets the upper critical solution point. Both branches of the coexistence curve are consistent with a critical exponent β=1, as expected for a symmetric tricritical point. The unpolymerized branch shows the discontinuity in slope with the polymerization line which is expected for a nonclassical symmetric tricritical point.

We show analytically that the expected number of fixed-point attractors in an associative memory neural network with analog neurons decreases exponentially as the neuron gain is reduced. Eliminating fixed-point attractors by using analog neurons has beneficial effects similar to stochastic annealing but can be easily implemented in a deterministic dynamical system such as an analog electronic circuit. Numerical data based on fixed-point counts in small networks support the analytical results.

The scattering of a nonlinear wave packet as an envelope soliton by a one-dimensional disordered system is studied. It is well known that in the linear limit the transmission coefficient decays exponentially with a characteristic localization length. We predict, using a simple independent scattering approach and soliton perturbation theory in the framework of the nonlinear Schrödinger equation, that strong nonlinearity above certain threshold allows undistorted propagation of wave packets.

We have carried out a modern version of the Kennedy-Thorndike experiment by searching for sidereal variations between the frequency of a laser locked to an ${\mathit{l}}_2$ reference line and a laser locked to the resonance frequency of a highly stable cavity. No variations were found at the level of 2×${10}^{\mathrm{-}13}$. This represents a 300-fold improvement over the original Kennedy-Thorndike experiment and allows the Lorentz transformations to be deduced entirely from experiment at an accuracy level of 70 ppm.

Sharp-energy S-matrix elements have been successfully extracted from a wave-packet description of three-boson and quartet-spin, neutron-deuteron scattering at energies well above the breakup threshold. Essential to the success of this procedure is use of an expansion basis comprising functions from each of the three two-cluster arrangements.

We show that the most general minimal supersymmetric standard model with ${\mathit{l}}_{\mathit{e}}$-${\mathit{l}}_{\mathrm{\mu }}$ symmetry (${\mathit{l}}_{\mathit{i}}$=ith lepton number) and a discrete horizontal symmetry between e and μ families can generate a large transition magnetic moment for the neutrino while leading to a naturally small mass. A magnetic moment of order ${\mathrm{\mu }}_{\nu }$≊0.3×${10}^{\mathrm{-}10}$${\mathrm{\mu }}_{\mathit{B}}$ implies ${\mathit{m}}_{\nu \mathit{e}}$=${\mathit{m}}_{\nu \mathrm{\mu }}$≥1 eV. The photino, which is expected to be the lightest supersymmetric particle, is unstable in this scheme, decaying dominantly into three-lepton final states (${\mathrm{\mu }}^{+}$ν${\mathrm{¯}}_{\mathit{e}}$${\mathrm{\tau }}^{\mathrm{-}}$, ${\mathrm{e}}^{+}$ν${\mathrm{¯}}_{\mathrm{\mu }}$${\mathrm{\tau }}^{\mathrm{-}}$+charge conjugate).

The renormalization-group evolution of Weinberg’s purely gluonic dimension-6 CP-violating operator is computed to first order in the QCD coupling constant, including its mixing with the quark color electric dipole moment. Our result for the anomalous dimension of the quark operator agrees with several previous calculations. For the gluonic operator, we find the anomalous dimension to have the same magnitude but opposite sign as a previous calculation. This significantly relaxes the constraints imposed on extensions of the standard model by experimental measurements of the neutron electric dipole moment.

Electron capture in keV collisions of protons with sodium atoms in the excited Na(3p) state is studied. The initial orbital alignment of the valence electron is controlled by the polarization of the exciting light. Capture into H(n) levels is measured for light polarization parallel and perpendicular to the proton beam direction. For n=2 the capture cross section is about 35% larger for an orbital aligned parallel than for one perpendicular to the beam direction, at all energies. However, for n≥3 the alignment effect varies dramatically with energy, supporting recent theoretical results.

Through resonance ionization measurements involving two-color, three-photon excitation, and four-photon ionization we observe very large, multiple, pressure-dependent line shifts in Xe. All features of the observed collective line shifts are in very close agreement with accompanying theoretical predictions.

We have observed bistability in the states of polarization of laser beams counterpropagating through sodium vapor. No external feedback is provided; the beams interact solely through four-wave mixing processes.

Magnetic-field effects accompanying ${\mathrm{O}}^{\mathrm{-}}$ photodetachment have been investigated using a high-resolution crossed-beams apparatus. Periodic structures in the photodetachment cross section, due to Landau resonances, have been observed in the previously uninvestigated regime at laser frequencies well above the reaction threshold and at very low magnetic-field strengths. The resonances have a Landau quantum number of about 3065.

Flow between two horizontal coaxial cylinders with a partially filled gap is investigated for the case when the primary instability forms a pattern of traveling inclined rolls which is simply periodic in space and time. Slightly above the onset, there is a second instability which results in a periodic modulation of the rolls with an axial wavelength of ∼3 rolls and a lower frequency. Both the traveling inclined rolls and the ∼3 roll modulation pattern exhibit long-wavelength low-frequency phase modulations and associated defects.

We consider a simple, nonlinear Hamiltonian model for particle motions in two-dimensional turbulence in which the stream function power spectrum has the form ${\mathit{k}}^{\mathrm{-}\gamma }$ (γ constant). We show that fluid particle trajectories, (1) while differentiable and chaotic at small scale, may be fractal space curves at larger scale, (2) undergo anomalous transport, and (3) have frequency spectra ∼${\mathit{f}}^{\mathrm{-}\mathrm{\alpha }}$ in fully stochastic limit, where we obtain α=α(γ), a scaling law. Anomalous diffusion is shown to arise partly as a result of the fractal nature of the particle trajectories.

A new principle, ‘‘cyclotron maser cooling’’ of electron and ion beams, is presented. Very rapid cooling times, below 1 ms, may be obtained for the transverse as well as for the longitudinal phase spaces of a beam.

A qualitatively new, ‘‘decoupled’’ phase of matter occurs in lamellar phases of tethered, crystalline membranes at large membrane separations d. This decoupled phase has no first-order elastic couplings between successive membranes; as a result, translational order falls off algebraically, with a universal exponent transverse to the membranes. The universal d dependence of the elastic constants is calculated, as is the critical separation ${\mathit{d}}_{\mathit{c}}$ at which the decoupling phase transition occurs. Untethered, crystalline membranes melt, as d is increased, at some d<${\mathit{d}}_{\mathit{c}}$.

A simple ballistic model for surface growth, which considers a mixture of ‘‘sticky’’ and ‘‘sliding’’ particles, is introduced and numerically investigated in dimensions d=2, 3, and 4. The model exhibits, in d=3 and 4 (but not in d=2), a roughening phase transition, of the type recently predicted by Halpin-Healy. For the first time it is shown that such kind of surface transition is accompanied by a transition in the bulk which is characterized by a singularity in the compacity-versus-concentration curve and which occurs at the threshold of a (d-1)-percolation transition.

Structural properties of CsI at high pressure have been investigated by the use of synchrotron x-ray diffraction techniques with the diamond-anvil cell at 300 K. The results indicate that the material undergoes a continuous distortion from B2 to an hcp-like phase, which is stable to at least 302 GPa. The intermediate orthorhombic phase is geometrically different from previous assignments and ∼10% denser. With the new structure, the p-V results of static pressure experiments, shock-wave studies, and theoretical calculations are now in good agreement.

A solid-state amorphization reaction is observed on hydrided, initially single-crystalline, ${\mathrm{Fe}}_2$Er powder samples (${\mathrm{Fe}}_2$${\mathrm{ErH}}_{\mathit{x}}$, 3.0<x<3.4). Specific-heat measurements at constant concentration (x=3.4) show pronounced premelting effects exhibiting a lambda-type transition at ${\mathit{T}}_{\mathit{c}}$=475.6 K and a logarithmic temperature dependence. This typical feature of an instability underlying the ‘‘melting’’ transition has been predicted if the vitrification occurs in the vicinity of the triple point between supersaturated crystal, undercooled liquid, and glass.

The energies of carbon defects in silicon are calculated, using an empirical classical potential, and used to infer defect properties and reactions. Substitutional carbon is found to react with silicon interstitials, with the carbon ‘‘kicked out’’ to form a (100) split interstitial. This interstitial can in turn bind to a second substitutional carbon, relieving stress, in three configurations with similar energies. The results here accord well with a variety of experimental data, including defect structures, activation energies for defect motion, and coupling to strain. A discrepancy with the accepted values for carbon solubility in silicon suggests a reinterpretation of the experimental data.