It is well known that the resonant tori of an integrable, classical Hamiltonian system break up under a small perturbation into new tori which wind around the remaining nonresonant tori. It turns out that the Maslov indices of one of these satellite tori depend on the Maslov indices of its unperturbed, resonant parent, and on the integers which enter into the resonance condition. They do not, however, depend on the functional form of the Hamiltonian or the perturbation. Our results are valid for any number of degrees of freedom.

The problem of linear mode conversion in nonuniform media is solved for general geometry, in that the dispersion functions ${\mathrm{D}}_{\mathrm{a}}$(k,x),${\mathrm{D}}_{\mathrm{b}}$(k,x) of the two, orthogonally polarized, coupled modes a,b have spatial gradients ∂${\mathrm{D}}_{\mathrm{a}}$/∂${\mathrm{x}}^{\mathrm{\mu }}$,∂${\mathrm{D}}_{\mathrm{b}}$/∂${\mathrm{x}}^{\mathrm{\mu }}$ which need not be parallel. The transmission ratio is found to be exp(-2π‖η${\mathrm{\Vert }}^2$/‖B‖), where η is the coupling coefficient, and B is the Poisson Bracket {${\mathrm{D}}_{\mathrm{a}}$,${\mathrm{D}}_{\mathrm{b}}$}=(∂${\mathrm{D}}_{\mathrm{a}}$/${\mathrm{\partial }}_{\mathrm{X}}^{\mathrm{\mu }}$)(∂${\mathrm{D}}_{\mathrm{b}}$/∂${\mathrm{k}}_{\mathrm{\mu }}$)${\mathit{D}}_{\mathit{b}}$) -(∂${\mathit{D}}_{\mathit{a}}$/∂${\mathit{K}}_{\mathrm{\mu }}$)(∂${\mathit{D}}_{\mathit{b}}$/${\mathrm{\partial }}_{\mathit{X}}^{\mathrm{\mu }}$). /∂${\mathrm{x}}^{\mathrm{\mu }}$). The further generalization to weak dissipation and ray divergence is included.

A lattice Virasoro algebra is constructed for the Baxter eight-vertex model. The operator ${\mathrm{L}}_0$ is obtained from the logarithm of the corner transfer matrix and is given by the first moment of the XYZ spin-chain Hamiltonian. The algebra is valid even when the Hamiltonian includes a mass term, in which case it represents lattice coordinate transformations which distinguish between even and odd sublattices. We apply the quantum inverse scattering method to demonstrate that the Virasoro algebra follows from the Yang-Baxter relations.

The data on low–transverse-energy jets obtained by the UA1 Collaboration in CERN SPS Collider experiments at c.m.-system energy 200 to 900 GeV are analyzed. It is observed that the low-$E_T$–jet events and the ordinary minimum-bias events are closely related to one another. Their relationship can be described by standard statistical methods. In particular, the existence of a narrow peak in the multiplicity distribution of low-$E_T$–jet events is a statistical effect caused by the small η-φ window with $E_T$ cut used in the selection of such events.

Two searches have been made for negatively charged massive elementary particles ($X^{\mathrm{-}}$) in iron nuclei by utilizing the fact that such systems would have the nuclear properties of iron but the chemical properties of manganese. We have looked for ${}_{}{}^{56}{}_{}{}^{}$,58Fe$X^{\mathrm{-}}$ by searching for γ rays emitted following the β decays of ${}_{}{}^{56}{}_{}{}^{}{X}^{\mathrm{-}}$ and ${}_{}{}^{59}{}_{}{}^{}{X}^{\mathrm{-}}$ produced by (p,n) and (n,γ) reactions, respectively. No evidence of such particles was observed in either experiment, and a limit has been established on the possible concentration of $X^{\mathrm{-}}$ particles in iron of <1.2×${10}^{\mathrm{-}12}$ per nucleon.

An accurate kinetics treatment is applied to the muonic helium atoms formed by a muon’s sticking to the charged particle produced in muon-catalyzed d-d and d-t fusion. Cross sections for l- and n- changing transitions are included to describe density-dependent stripping and x-ray production. Coupled with recent accurate calculations of the initial sticking, the results are generally in very good agreement with experiments. The noteworthy exception is that the density dependence of the sticking is much weaker than previously observed, in agreement with preliminary results of a new experiment.

Results of a theoretical study of the permeability k and proton relaxation rate ${\mathrm{T}}_1^{\mathrm{-}1}$ in fully and partially saturated porous media are presented. Numerical calculations on two distinct geometrical models of granular materials predict a strong correlation between k and ${\mathrm{\phi }}^4$${\mathrm{T}}_1^2$ for fully saturated systems (with porosity φ) in agreement with a recent experimental study.

Self-induced stochastic behavior for the evolution of light along a periodically perturbed two-mode nonlinear optical waveguide is predicted. Implications for recently demonstrated all-optical switching using birefringent fibers are discussed.

A Lagrangian has been developed that leads to equations of motion which are isomorphic to the full Navier-Stokes equation, including dissipation. This Lagrangian has been developed to give a many-body description turbulence along the standard lines of most field theories.

In this Letter, we give closed-form solutions for the dielectric function and the electron density fluctuation spectrum in a weakly-collisional electron-ion plasma in thermodynamic equilibrium by solving the linearized Balescu-Lenard-Poisson kinetic equations. When the collisionless and collisional formulae for the fluctuation spectra are compared at long wavelengths, we find that electron-ion collisions are dominant and enhance the fluctuations for ω near zero and near the ion-acoustic wave frequency.

The cross-field electron thermal conductivity coefficient, ${\mathrm{\kappa }}_{\mathrm{\perp }}$, in an electron-beam–heated cylindrical magnetoplasma (${\mathrm{n}}_0$∼3×${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}3}$; ‖${\mathrm{B}}_0$‖=30 G, 120 G; ${\mathrm{V}}_{\mathrm{b}}$=200 V; ${\mathrm{I}}_{\mathrm{b}}$≤2.5 A, ${\mathrm{t}}_{\mathrm{b}}$≤5 μs) is measured. Results are compared with classically predicted values. After beam turnoff, ${\mathrm{\kappa }}_{\mathrm{\perp }}$ approaches within a factor of 3 the classical value, except for the case ${\mathrm{I}}_{\mathrm{b}}$=1.5 A, ‖${\mathrm{B}}_0$‖=120 G. For that case, and during the beam pulses, ${\mathrm{\kappa }}_{\mathrm{\perp }}$ is found to be anomalously high, by up to over 2 orders of magnitude above the classical value.

Stochastic acceleration of plasma ions is observed in the field of an intense electrostatic wave. Both electrostatic ion cyclotron and ion Bernstein waves are launched from antennas at the plasma boundary, and ion motions are observed by laser-induced fluorescence. The threshold for stochastic ion heating is observed for the first time. As anticipated, the ion distribution function changes rapidly above threshold (on a cyclotron-period time scale). Measurements of the wave electric field and the ion distribution function indicate that the ion Bernstein wave is responsible for the ion accelerations.

Ellipsometric measurements of the thickness of the liquid-vapour interface of carbon tetrachloride between room temperature and near the critical temperature are shown to indicate that the surface thickness is determined by capillary wave excitations at large t=(${\mathrm{T}}_{\mathrm{c}}$-T)/${\mathrm{T}}_{\mathrm{c}}$, but by an intrinsic interfacial thickness at small t, the crossover occuring when δ/d lies in the range between 1 and 2, where δ is a measure of the thickness and d is the molecular diameter.

Observations on the (111) surface of Ge crystal at elevated temperatures have been made by low-energy-electron diffraction with position-sensitive detection. The results indicate that the outermost few atom double layers lose lateral crystalline order in a continuous phase transition 150 K below the bulk melting temperature.

We report synchrotron x-ray powder-diffraction measurements of the Al-Li-Cu icosahedral phase. Our results are found to be in agreement with the computed diffraction intensities of the three-dimensional Penrose tiling when Al and Cu atoms are randomly positioned at the vertices and edge centers of the unit cells. Comparison is also made with a similarly decorated icosahedral structure constructed by dense packing of icosahedra. The agreement is less satisfactory.

Uniformly sized microspheres confined to thin layers between solid boundaries are used to demonstrate pattern formation in diffusion-controlled aggregation. Extremely slow growth processes monitored over several months show faceted hexagonal lattices. For successively faster growth, dendritic crystals and ramified aggregates are formed. The results are compared with recent studies of local and global growth models.

The use of polarized light to generate oriented paramagnetic centers in glass is discussed. Analytic expressions are derived for the resultant EPR lineshape, and are compared to experimental results obtained for a-${\mathrm{SiO}}_2$. Analysis of the EPR anisotropy provides information concerning the formation mechanism of the paramagnetic center and about the degree of lattice relaxation following the formation of the center.

Tight-binding calculations of the surface-phonon dispersion curves for unreconstructed p(1×1) W(001) reveal a whole region of soft surface modes at the boundary of the surface Brillouin zone, caused by interactions with electronic surface states around ${\mathrm{E}}_{\mathrm{F}}$. An interplay of Fermi-surface nesting features and real-space d-orbital interactions leads to the maximum instability of the M${\mathrm{¯}}_5$ phonons, the basis of the observed c(2×2) reconstruction patterns. For small H coverages the electronic surface states are not removed but modified, probably in such a way as to produce incommensurate reconstructions.

Electronic-structure and total-energy calculations are reported for the vacancy and the substitutional and interstitial S, Se, and Te impurities in Si. We identify several mechanisms of impurity-impurity interactions. This theoretical study also serves to determine the dominant defect site of chalcogen pairs as two substitutionals.

A new variant of the usual x-ray standing-wave experiment, scanning the Bragg reflection in energy at normal incidence, is shown to be applicable to metal crystals without special precautions being taken to ensure high crystalline perfection. The structure of the Cu(111)(√3 × √3 )R30°-Cl chemisorption phase is found to be compatible with the results of a previous surface extended x-ray-absorption fine structure and photoelectron diffraction study.