Scanning tunneling microscopy and low energy electron diffraction studies of mixed O+N layers on Rh(110) reveal a competition between (n×1) N-driven and (1×2) O-driven added/missing row reconstructions. At low coverage [001] N-Rh rows prevail, forming islands with a (3×1) periodicity. At moderate coverage separate (2×1)N and (1×2)O islands are formed. At high coverage the growing (1×2)O islands displace those of (2×1)N. The structural transformations involve a transition from a structure consisting of separate (2×1)N and (1×2)O islands to a mixed c(2×2)N+O layer on a (1×2) reconstructed surface.

Experimental quasi-two-dimensional Zn electrodeposits are grown under forced convection conditions. Large-scale effects, with preferential growth towards the impinging flow, together with small-scale roughness suppression effects are evidenced and separately analyzed by using two different radial cell configurations. Interpretations are given in terms of primary concepts concerning current and concentration distributions.

Competition between Mott and Anderson metal-insulator transitions is studied in a one dimensional spinless fermion system of 200 sites. Although the long range charge density wave (CDW) order and gap of the Mott phase are destroyed by weak randomness, the elementary excitations are still solitons based on the local CDW order. The solitons are easily localized in the random potential. Thus for weak randomness and large interaction, a disordered Mott phase exists in which the localization is determined by the local CDW order in contrast to the conventional Anderson localization picture in the weak interaction limit.

Resonant tunneling between fractional quantum Hall edge states is studied in the Luttinger liquid picture. For the ν=1/3 Laughlin parent state, the resonance line shape is a universal function whose width scales to zero at zero temperature. Extensive quantum Monte Carlo simulations are presented for ν=1/3 which confirm this picture and provide a parameter-free prediction for the line shape.

Individual two-state and multistate fluctuators were found in the broadband noise in the sliding charge-density–wave (CDW) state of small samples of ${\mathrm{NbSe}}_3$. In the presence of dc currents, some multistate fluctuators violate detailed balance. Fluctuator properties show strong dependences on bias. As the CDW is cycled from sliding to pinned and back, it usually remembers which state of the fluctuator it is in, but some finite transition rates are found in the pinned CDW. Similar fluctuators persist in the presence of high-frequency ac bias.

Lateral superstructures with honeycomb symmetry are shown to be classified, with a simple criterion, into semimetals with gapless k-linear dispersions, semiconductors, and metals. In some of the classes, the symmetry enforces flat bands to exist, which implies the occurrence of ferromagnetism when the electron correlation is turned on. These provide a unique opportunity for band structure engineering.

The ground state properties of the two dimensional spatially anisotropic Heisenberg model are investigated by use of field theory mappings, spin-wave expansion, and Lanczos technique. Evidence for a disorder transition induced by anisotropy at about ${\mathit{J}}_{\mathit{y}}$/${\mathit{J}}_{\mathit{x}}$<0.1 is shown. We argue that the disordered phase is gapless and its long wavelength properties can be interpreted in terms of decoupled one dimensional chains.

We report the first systematic transient dynamics measurements of a cellular instability during directional solidification on a nematic-isotropic interface of the liquid crystal 8cB. The time evolution of the most unstable spatial mode of the interface is well described by a third-order Landau-amplitude equation, as anticipated theoretically. Instability growth rates and nonlinear cubic coefficients are measured as a function of pulling velocity and temperature gradient. The results are compared with theories of directional solidification.

A search for symmetries based on the compact simple Lie algebras is performed to verify to what extent the genetic code is a manifestation of some underlying symmetry. An exact continuous symmetry group cannot be found to reproduce the present genetic code. However, a unique approximate symmetry group is compatible with codon assignment for the fundamental amino acids and the termination codon. In order to obtain the actual genetic code, the symmetry must be slightly broken.

After establishing a formal theory for getting solutions of one type of high-dimensional partial differential equation, two sets of generalized symmetries of the 3D Toda theory, which arises from a particular reduction of the 4D self-dual gravity equation, are obtained concretely by a simple formula. Each set of symmetries constitutes a generalized ${\mathrm{\omega }}_{\mathrm{\infty }}$ algebra which contains three types of the usual ${\mathrm{\omega }}_{\mathrm{\infty }}$ algebras as special cases. Some open questions are discussed.

A novel mathematically simple and physically transparent derivation of the Efimov effect is presented by means of a new efficient method for solving coordinate space Faddeev equations. The method, which is directly applicable on small computers, is used to obtain energies and wave functions of the Efimov states.

We show how, combining their outputs, at least six resonant bar antennae give with isotropic sensitivity the amplitude, polarization, and direction of propagation of a burst and test for two distinctive properties of the Riemann tensor, transversality, and tracelessness. If not located at the same site, to exert the two vetoes, the burst arrival times on three antennae must be known: We show how to determine them. Then in addition the propagation of the burst at light velocity is tested.

Using the CLEO II detector and a sample of 955 000 Υ(4S) decays we have confirmed charmless semileptonic decays of B mesons. In the momentum interval 2.3–2.6 GeV/c we observe an excess of 107±15±11 leptons, which we attribute to b→ulν. This result yields a model-dependent range of values for ‖${\mathit{V}}_{\mathit{u}\mathit{b}}$/${\mathit{V}}_{\mathit{c}\mathit{b}}$‖ that is lower than has been obtained in previous studies. For the inclusive spectator model of Altarelli et al. we find ‖${\mathit{V}}_{\mathit{u}\mathit{b}}$/${\mathit{V}}_{\mathit{c}\mathit{b}}$‖=0.076±0.008. Models that describe b→ulν with a limited set of exclusive final states give ‖${\mathit{V}}_{\mathit{u}\mathit{b}}$/${\mathit{V}}_{\mathit{c}\mathit{b}}$‖=0.06-0.10.

Orbitally excited heavy-light (Qq¯) mesons are potentially important as tools for tagging the flavors and momenta of ground-state pseudoscalars detected through weak decays. We use heavy-quark symmetry supplemented by insights gleaned from potential models to estimate masses and widths of p-wave B, ${\mathit{B}}_{\mathit{s}}$, and ${\mathit{D}}_{\mathit{s}}$ mesons. We generalize these results to higher excitations.

A search for invisible axions is carried out by looking for invisible M1 transitions in ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$(5/$2^{+}$→7/$2^{+}$) with a transition energy of 166 keV. A limit to the branching ratio of axion emission to that of γ emission is obtained to be ${\mathrm{\Gamma }}_{\mathit{a}}$/${\mathrm{\Gamma }}_{\gamma }$<1.21×${10}^{\mathrm{-}6}$ at the 95% confidence level. Hadronic axions heavier than 26.7 keV are excluded by this upper limit. It is also concluded that the branching ratio of the second forbidden electron capture decay of ${}_{}{}^{139}{}_{}{}^{}\mathrm{Ce}$ into the ground state of ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$(7/$2^{+}$) is less than 9.7×${10}^{\mathrm{-}7}$ at the 95% confidence level.

The mass of the nucleus ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ has been determined from a measurement of the $Q$ value of the reaction ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$,${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$)${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$ at $\frac{E}{A}\approx 32$ MeV. The results, which indicate a two-neutron separation energy of $S_{2n}\left({}_{}{}^{11}{}_{}{}^{}\mathrm{Li}\right)=295\mathrm{}\pm 35$ keV, put this basic quantity on a firm basis for use in theoretical models of the halo nucleus ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$.

The charge transfer rate coefficient for the reaction ${\mathrm{O}}^{2+}$+He→${\mathrm{O}}^{+}$+${\mathrm{He}}^{+}$ was measured at energies about 2.5 eV (2×${10}^4$ K) using a laser-induced-plasma ion source and ion storage. The rate coefficient is 1.12(0.14)×${10}^{\mathrm{-}12}$ ${\mathrm{cm}}^3$ ${\mathrm{s}}^{\mathrm{-}1}$, and disagrees with the available theoretical value. Our measured rate coefficient is also different from the value obtained by drift tubes at lower energies by at least an order of magnitude. The charge transfer rate coefficient for ${\mathrm{O}}^{2+}$ and the residual gas (${\mathrm{H}}_2$, ${\mathrm{H}}_2$O, and CO) of the ultrahigh vacuum system is estimated to be ∼5×${10}^{\mathrm{-}9}$ ${\mathrm{cm}}^3$ ${\mathrm{s}}^{\mathrm{-}1}$.

Only a relatively small number of metallic clusters exhibit a stable spherical shape. We show that the majority of such clusters tend to acquire deformed shape, in order to minimize the fluctuating part of the total energy, due to the bunching of the single particle electronic levels in a confined geometry. We have found also that there is a large number of low lying shape isomers. Often the deformation energy surface develops rather wide shallow pockets and such clusters are particularly easy to deform. As a function of the electron number the cluster ground state deformations and isomer energies show some remarkable regularities.

Recently it has been shown that there are chaotic attractors whose basins are such that every point in the attractor’s basin has pieces of another attractor’s basin arbitrarily nearby (the basin is ‘‘riddled’’ with holes). Here we report quantitative theoretical results for such basins and compare with numerical experiments on a simple physical model.

Proofs that Fredholm determinants of transfer operators for hyperbolic flows are entire can be extended to a large new class of multiplicative evolution operators. We construct such operators both for the Gutzwiller semiclassical quantum mechanics and for classical thermodynamic formalism, and introduce a new functional determinant which is expected to be entire for Axiom A flows, and whose zeros coincide with the zeros of the Gutzwiller-Voros zeta function.