By introducing finite-size-scaling corrections into the Kelvin equation for the location of the shifted first-order phase boundary (condensation line) for a fluid confined between two parallel plates, the critical exponent μ̃ for the liquid-gas surface tension is shown to satisfy the Widom exponent relation μ̃=2-α-ν. In contrast to most previous arguments, no assumptions of bulk and surface hyperscaling are required in the present derivation.

The dependence of the structural relaxation rates at a crystal-liquid surface on the degree of local order introduces a distribution of relaxation rates. The steady-state behavior of a nonequilibrium planar crystal-liquid surface with such an order-parameter-dependent kinetic coefficient is studied using numerical solutions of a Landau-Ginzburg equation for a single nonconserved order parameter. The selected steady-state velocity is found to decouple from the slow relaxation rate of the solid as the supercooling is increased, giving rise to a nonlinear dependence of the velocity on the supercooling. This decoupling is accompanied by the appearance of an extended region of disorder on the solid side of the interface.

An alternative system of magnetohydrodynamic equations for relativistically hot electron-positron plasmas is derived. The results should be useful for studying low-frequency wave motions as well as instabilities in astrophysical systems.

Dynamic behavior of neural networks is studied via the dynamic mean-field theory for the Little-Hopfield model and for the dynamic model. In both models, the existence of the generalized Almeida-Thouless lines and associated dynamic instabilities are revealed. On these lines, autocorrelation functions are found to decay algebraically with exponent 1/2, while they decay exponentially above the lines.

This comment corrects an explanation, given in a recent and interesting paper by Masoliver, Porra, and Weiss [Phys. Rev. A 45, 2222 (1992)], to account for one of the discontinuities of the probability density of the telegrapher process in the presence of a trap. The discontinuity is due to the trapping of the random walkers that would have undergone one reversal if there were no trap, instead of ‘‘reflections from the trapping point, i.e., from particles which reach the trap but reverse direction when they reach that point’’, quoting from the authors.

This reply adds a number of details to remarks by Foong and Kanno [preceding Comment, Phys. Rev. A 46, 5296 (1992)] on our paper [Phys. Rev. A 45, 2222 (1992)] regarding the discontinuities observed in the curves generated in that paper.

In the functional Schrödinger picture a relativistic massless quantum field can for certain states behave as a massive field due to the influence of the quantum potential.

We report our recent results of the measurement of the binding energy of the ground state of the calcium negative ion using electric field dissociation and accelerator mass spectrometry. The electron affinity of Ca was measured to be 17.$5_{\mathrm{-}2}^{+4\mathrm{}}$ meV for a p-wave electron emission, which is in good agreement with recent photodetachment experiments performed by Walter and Peterson [Phys. Rev. Lett. 68, 2281 (1992)].

A simple and accurate procedure for calculating the rate of double photoionization of ‘‘two-electron’’ systems at very high photon energies is presented. Arguments are given to support the validity of the method used. In particular, we show that the many-body perturbation theory diagrams depend asymptotically on the choice of the gauge for the electric dipole operator. The ratio of double-to-single ionization is calculated to be 1.68% in agreement with the recent synchrotron measurements. For ${\mathrm{H}}^{\mathrm{-}}$ and ${\mathrm{Li}}^{+}$, we predict ratios of 1.51% and 0.89%, respectively.

We report on measurement of secondary-electron emission (SEE) induced by hydrogen clusters (${\mathrm{H}}_{\mathit{n}}^{+}$, n≤19, odd) from thin carbon foils for beam velocities above and around the Bohr velocity. The n dependence of the SEE yield shows a strong inhibition effect with respect to the atomic case. At a given velocity, the inhibition effect is observed first to increase with n and then to reach a saturation value (n≥7). These results are connected to the understanding of the inhibition effects observed with molecular beams.

We have experimentally investigated the density behavior of the depolarized-interaction-induced light-scattering line shape of compressed gaseous argon at T=298 K and up to pressure p=262 MPa, i.e., to densities n=19.7 atoms/${\mathrm{nm}}^3$. We have been able to measure the spectral behavior down to the frequency ν≊15 GHz. These low-frequency measurements have permitted the study in detail of the effect of the intensity cancellation which, in the line shape, manifests itself by means of a strong density-dependent rounding of the spectra below ≊900 GHz.

We present experimental evidence of light-induced vapor jets produced by the light-induced-drift effect. They are observed in a cell kept at room temperature, having the active atom source in its central part. The cell has a diameter much larger than that of the laser beam in order to eliminate all interactions with the cell walls. This experiment opens the possibility of studying atomic elements with extremely high temperature of evaporation and/or strong chemical reactivity.

Illuminating a gold surface by strong (5 GW/${\mathrm{cm}}^2$) picosecond neodymium-doped yttrium aluminum garnet laser pulses at grazing incidence, we observed a generation of coherent beams of both even and odd harmonics up to fifth order in the reflected direction with efficiencies ${10}^{\mathrm{-}10–}$${10}^{\mathrm{-}13}$. The observed decrease of the harmonic efficiencies with increasing harmonic order is much weaker than predicted by perturbative theories.

The mean-field model of optical bistability in a ring cavity is extended to include diffraction in two transverse dimensions. Nonlinear analysis in the neighborhood of the instability of the homogeneous solution indicates the formation of stable hexagonal patterns, and this is confirmed by numerical simulation, with reasonable quantitative agreement. Simulations with higher excitation show defect structures and complex dynamical patterns.

We analyze lasing without inversion in a V system driven by a single optical field. This is shown to depend on the relaxation rates and photon degeneracy parameters of the system and occurs for a broad range of lasing intensities. The physical mechanism is explained in terms of trapping of the modified ground state, which is coherently split by the optical pump field.

An alternative theoretical treatment of the order-disorder transition in periodically driven instabilities such as Rayleigh-Bénard convection is presented. The decay of the correlation function of the order parameter is calculated by using a general eigenvalue analysis of the Kolmogorov operator. It is shown that the boundary between stochastic and deterministic behavior found experimentally can be understood as a transition between regimes where the order parameter is, respectively, statistically uncorrelated and correlated in subsequent time periods.

We study the critical behavior of period-doubling bifurcations in two coupled one-dimensional maps. In a linear-coupling case, in which the coupling function has a leading linear term, the set of critical points, called the critical set, consists of an infinite number of critical line segments and the zero coupling point, whereas only one critical line segment constitutes the critical set in the case of a nonlinear coupling whose leading term is nonlinear. We find three (two) kinds of critical behaviors in the linear (nonlinear) coupling case, depending on the position on the critical set.

We describe the results of an analytical and numerical study of the geometrical properties of random spanning trees on a square lattice. We determine exactly the probability distribution of the coordination number at a site on a random spanning tree. We argue that the probability that s sites get disconnected from the tree on deleting a bond at random from the tree varies as ${\mathit{s}}^{\mathrm{-}11/8}$ for large s. The probability that a loop of perimeter l is formed on adding an additional link at random varies as ${\mathit{l}}^{\mathrm{-}8/5}$ for large l. These distributions are also determined numerically in a Monte Carlo simulation on random spanning trees generated by using Broder’s algorithm. The numerical results are in complete agreement with the theoretical predictions.

A simple method for testing whether broadband noise comes from driven dynamical effects (rather than equilibrium fluctuations) is described. Asymmetrical higher-order time correlation functions can violate detailed balance, providing a key signature of dynamical effects. Simulations of a one-dimensional sandpile model are used for an initial illustration. Also, a hitherto unreported phenomenon—growth of the non-Gaussian nature of the statistics with system size—is found and attributed to the presence of correlations on the scale of the whole system.

We study the surface fluctuations of the one-dimensional limited local sandpile (LLS), a numerical model that exhibits self-organized criticality. We argue that certain apparently anomalous features can be understood when the model is viewed as a limiting case of a family of noncritical models. The criticality of the LLS is shown to result from a hidden symmetry which may not be present in real sandpiles.