The problem of the production of helium in the big bang is reexamined in the light of several recent astrophysical observations. These data, and theoretical particle-physics considerations, lead to some important inconsistencies in the standard big-bang model and suggest that a more complicated picture is needed. Thus, recent constraints on the number of neutrino flavors, as well as constraints on the mean density (openness) of the universe, need not be valid.

The equation governing four-wave interactions in a nonlinear dispersive system is studied. It is shown that a nonlinear steady-state plane wave can bifurcate into nonplanar steady-state solutions. In the case of an isotropic medium, the bifurcation is degenerate and the bifurcated solutions may preserve or break the symmetry. An example is given of a symmetry-breaking solution for deep-water gravity waves and its stability is discussed.

For a certain class of three-manifolds, the angular momentum of an asymptotically flat quantum gravitational field can have half-integral values.

Short-lived particles produced in association with muons have been observed in the interactions of 350-GeV/c protons with neon in a high-resolution streamer chamber. The characteristics of these events are consistent with the expected properties of charmed particles if the average lifetime lies between ${10}^{-13\mathrm{}}$ and 2×${10}^{-12\mathrm{}}$ sec. With the assumption that the observed events are mainly $D^{\pm }$ mesons with lifetimes of approximately ${10}^{-12\mathrm{}}$ sec, the production cross section is estimated to lie between 20 and 50 μb per nucleon.

Three narrow resonances have been observed in $e^{+}{e}^{-}$ annihilation into hadrons at total energies between 9.4 and 10.4 GeV. Measurements of mass spacing and ratios of lepton pair widths support the interpretation of these "$\Upsilon$" states as the lowest triplet-$S$ levels of the $b\overline{b}$ quark-antiquark system.

The $\Upsilon$, ${\Upsilon }^{\prime }$, and ${\Upsilon }^{\prime \prime }$ states have been observed at the Cornell Electron Storage Ring as narrow peaks in $\sigma (e^{+}{e}^{-}\to \mathrm{hadrons})$ versus beam energy. Data were collected during a run with integrated luminosity of 1000 ${\mathrm{nb}}^{-1\mathrm{}}$, using the Columbia University-Stony Brook segmented NaI detector. The measured mass differences are $M\left({\Upsilon }^{\prime }\right)-M\left(\Upsilon \right)=559\mathrm{}\pm 1(\pm 3)$ MeV and $M\left({\Upsilon }^{\prime \prime }\right)-M\left(\Upsilon \right)=889\mathrm{}\pm 1(\pm 5)$ MeV, where the errors in parentheses represent systematic uncertainties. Preliminary values for the leptonic width ratios were also obtained.

A complete set of the pointlike monopole solutions for the group SU(3) is presented which can describe arbitrary allowed magnetic charges. The method adopted to construct the solutions makes use of the topological structure of the non-Abelian symmetry and could be applied to an arbitrary gauge group $G$.

Let ${\sigma }_P(Q^2, s)$ be the total cross section for scattering of meson $P$ on some target, with $-Q^2$ the off-shell mass of $P$. It is shown that, when $-Q^2\ne {m_P}^2$ (the physical $P$ mass), quantum chromodynamics suggests that, as the c.m. energy squared $s$ approaches $\infty$, ${\sigma }_P(Q^2, s)\sim C_{1}f\left(Q^2\right)s^{\lambda }+\dots , \lambda >0,$ where $f\left(Q^2\right)$ is calculable for large $Q^2$. This is compatible with the Froissart bound, but only for on-shell particles, provided $f(-{m_P}^2)=0\mathrm{}$. It is shown that there is experimental evidence supporting such behavior.

Isotope-selective laser excitation has been used to study excitation exchange in collisions of helium Rydberg atoms with ground-state helium; this process is dominated by the interaction of the ionic core with the neutral atom and proceeds at the charge-exchange rate, the excited electron remaining a spectator.

Doubly excited even-parity 1snpmp ${}_{}{}^2{}_{}{}^{}P$ states of neutral Li are metastable against auto-ionization and have large radiative yields. An emission spectrum from 160 Å to 250 Å of a high-power-microwave-heated Li plasma is reported. The spectrum, which differs substantially from that obtained in absorption, exhibits several new series as well as the phenomena of radiative autoionization.

Inward energy transport ranges in layered targets have been measured as a function of the irradiance of short-pulse C${\mathrm{O}}_2$-laser light. As electromagnetic ponderomotive effects become important, the penetration of thermal electrons is sharply reduced and the penetration of suprathermal electrons increases much more slowly with irradiance. These results are discussed in the context of target implosions driven by suprathermal electrons.

Results from the tandem mirror experiment are described. The configuration of axial density and potential profiles are created and sustained by neutral-beam injection and gas fueling. Plasma confinement in the center cell is shown to be improved by the end plugs by as much as a factor of 9. The electron temperature is higher than that achieved in our earlier $2\mathrm{XII}B$ single-cell mirror experiment.

We analyze the metastable states for individual atoms within a computer-generated structural model of a metallic glass, and discover that their probability of occurrence is a strong function of the degree of relaxation of the model. We propose that the relaxation process simulates closely the annealing of metallic glasses below the glass transition temperature, so that the annealing process should reduce the magnitudes of the various low-temperature anomalies seen in these materials.

The first observation of low-energy positron diffraction from a solid surface is reported. Slow (20-400-eV) monochromatic positron beams were focused onto a Cu(111) surface and their elastically scattered distributions detected with a channel electron multiplier. Measurements of the scattered intensity versus angle as a function of incident energy show peaks at the predicted ($0\overline{1}$) and ($0\overline{2}$) diffraction angles. Profiles of intensity versus energy at fixed angles exhibit maxima corresponding to the primary Bragg peaks.

The fluxoid quantization condition for a thin superconducting cylinder causes a change in the order parameter to result in a change in the frozen-in magnetic flux. By measuring with a SQUID the change in magnetic flux for a superconducting aluminum cylinder under microwave irradiation it is found that the order parameter increases as a function of the microwave power. Order-parameter changes with changing temperature are observed also, and they are in agreement with theoretical expectations for a dirty superconductor.

The magnetic hysteresis of superconducting niobium single crystals containing ∼80-Å-diam nitride precipitates was investigated. Introducing precipitates into the samples produced no significant change in the critical-current density $J_c$ except near the critical fields $H_{c1\mathrm{}}$ and $H_{c2\mathrm{}}$. The samples trapped flux below $H_{c1\mathrm{}}$ and exhibited dramatic peaks in $J_c$ within 3% of $H_{c2\mathrm{}}$. These observations are interpreted as clear evidence of a threshold for fluxoid pinning, and reasonable agreement with theory is obtained.

The temperature dependence of the electrical resistivity of granular aluminum films changes from one regime to another as their superconducting transition temperatures drop towards absolute zero. In nonsuperconducting specimens we observe the exponential behavior associated with strong localization. In the other regime the specimens show a weaker, logarithmic dependence.

We have measured the resistance of electron inversion layers in Si metal-oxide-semiconductor field-effect transistors at low temperatures (∼50 mK) and low electric fields (∼0.1 V/m). At low values of $R_{\square }$ we observe logarithmic dependences of the resistance on both temperature and applied electric field which scale only on $R_{\square }$. We observe a gradual transition to an exponential dependence at $R_{\square }\gtrsim 10$ kΩ. The logarithmic dependences agree qualitatively but not quantitatively with current theories of localization.

The intramolecular binding of carbon monoxide (${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$/${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$/${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ mixtures) to myoglobin at 20 and 60 K is observed with time-resolved Fourier-transform infrared spectroscopy. The binding rates (at ≈ 1 ks) for the molecules ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ are in the ratio 1:0.84:0.65 at 20 K, 1:0.87:0.84 at 60 K. The large isotope effect confirms earlier evidence for molecular tunneling. The fact that ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ binds faster than ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ implies that structure effects are significant in molecular tunneling.

Kramers's modeling of a chemical reaction by barrier-mediated diffusion is generalized to include a possible spatial variation of viscosity along the reaction coordinate. Expressions are derived for the rate coefficient $k$,$k$ is influenced by the viscosity at the location of the barrier top, which is partially affected by the solvent viscosity $\eta$. A predicted law $\delta \left(\ln k\right)=\epsilon \delta \left(\ln \eta \right)$ for $0<~\epsilon <~1$ is compatible with recent kinetic measurements in proteins.