A new nonequilibrium technique is used to investigate the intermolecular forces that determine the thickness of wetting layers in the system methylcyclohexane plus perfluoromethylcyclohexane on silicon near the critical point of the liquids. When the liquids are subjected to a linear temperature ramp, the resulting deviation from equilibrium controls the thickness of the methylcyclohexane-rich wetting layer. Ellipsometric measurements of the layer thickness for thermodynamic states corresponding to temperatures 0.5 to 50 mK above the coexistence curve agree quantitatively with theoretical calculations. As the distance from coexistence decreases, the layer thickness smoothly increases and shows a crossover from adsorption dominated by the nonzero correlation length to adsorption dominated by dispersion forces. The measurements also confirm that correlations in the concentration decay exponentially, out to at least five correlation lengths. Equilibrium measurements on an off-critical concentration cell in the single-phase region agree with theory for temperatures greater than 0.2 K from the coexistence curve, but show marked irreproducibility within 0.2 K of the transition.

A diffusion-limited-aggregation (DLA) model with two components (A and B species) is presented to investigate the structure of the composite deposits. The sticking probability ${\mathit{P}}_{\mathit{A}\mathit{B}}$ (=${\mathit{P}}_{\mathit{B}\mathit{A}}$) between the different species is introduced into the original DLA model. By using computer simulation it is shown that various patterns are produced with varying the sticking probabilities ${\mathit{P}}_{\mathit{A}\mathit{B}}$ (=${\mathit{P}}_{\mathit{B}\mathit{A}}$) and ${\mathit{P}}_{\mathit{A}\mathit{A}}$ (= ${\mathit{P}}_{\mathit{B}\mathit{B}}$), where ${\mathit{P}}_{\mathit{A}\mathit{A}}$ (=${\mathit{P}}_{\mathit{B}\mathit{B}}$) is the sticking probability between the same species. Segregated patterns can be analyzed under the condition ${\mathit{P}}_{\mathit{A}\mathit{B}}$<${\mathit{P}}_{\mathit{A}\mathit{A}}$, assumed throughout the paper. With decreasing sticking probability ${\mathit{P}}_{\mathit{A}\mathit{B}}$, a clustering of the same species occurs. With sufficiently small values of both sticking probabilities ${\mathit{P}}_{\mathit{A}\mathit{B}}$ and ${\mathit{P}}_{\mathit{A}\mathit{A}}$, the deposit becomes dense and the segregated patterns of the composite deposit show a striped structure. The effect of the concentration on the pattern morphology is also shown.

Computer simulations of ballistic driven accretions on seeds of different sizes were carried out. The results, in agreement with previous work reported for the general case of seeds of particle size, show that the kinematics of accretion does not depend on the size of the seed. Specific morphological properties (growth angle and channel orientation) are investigated and found to depend only on the elementary aggregation process.

The crystallization of Al-Ge alloy amorphous thin films reveals a unique, dense branching morphology. Such morphology is found in other systems, i.e., electrodeposition and the Hele-Shaw cell, but so far this is the only known case in the field of materials science. A detailed description is given of the structure, morphology, and composition of the crystallized films and of the material processes that are involved in the crystallization of the Al-Ge alloy, and which are responsible for the unique morphology. The role played by diffusion is particularly emphasized.

Thermal x-ray confinement in a laser-heated gold cavity was investigated. Intense blue laser light (wavelength 351 nm, energy 5 kJ, duration 0.9 ns) irradiated the inner surface of (1–3)-mm-diam gold shells at average intensities up to 2×${10}^{14}$ W/${\mathrm{cm}}^2$ to generate the source x ray for the confinement. A maximum brightness temperature of 240 eV and a quality factor of confinement of N=5.3 (corresponding to a reemission coefficient of r=0.84) have been achieved. Experimental results are in satisfactory agreement with theoretical predictions based on the self-similar ablative heat wave driven by radiation and with numerical simulations.

We report results of Helmholtz-free-energy and internal-energy calculations using the modified hypernetted-chain (MHNC) equation method, in the formulation of Lado, Foiles, and Ashcroft [Phys. Rev. A 28, 2374 (1983)], for a model plasma of ions linearly screened by electrons. The results are compared with HNC calculations (no Bridge term), with variational calculations using a hard-spheres reference system, and with a numerical fit of Monte Carlo simulations.

The Lyman-α profile of hydrogen was studied in a gas-linear pinch, the plasma parameters of which were determined by Thomson scattering. The profiles displayed pronounced first- and second-order dips. The theory of dips in profiles of hydrogenlike spectral lines in plasmas containing quasimonochromatic electric fields, e.g., plasma waves or microwaves, is therefore further developed for high-density plasmas. The central point is the allowance of a spatial nonuniformity of the ion microfield that becomes more important with increasing density. Three qualitatively new features of the ‘‘dip’’ effect arise: (1) a significant shift of the dip positions (mostly to the blue side), (2) an appearance of dips in profiles of the central Stark components, and (3) an appearance of higher-order dips due to multiquantum resonances (between plasma waves and quasistatic Stark splitting). The measured blueshifts of the first- and the second-order dips are in fairly good agreement with the predictions of the present theory. This shift is much larger than the shift of the spectral line as a whole. The amplitude of the plasma waves as estimated from the measured half-widths of the dips was of the order of 2 MV/cm.

The melting of the DNA double helix is treated within an effective-phonon theory for a simplified model of a double strand of particles (nucleotides) interacting through harmonic stacking forces and anharmonic hydrogen bonds represented by potentials V(u)=1/2${\mathit{Bu}}^2$-Cγ${\mathit{u}}^3$. Analytical expressions are given for the melting temperature and the critical bond stretch, as well as for the temperature scaling of the entropy and heat capacity below the critical point. The model also accommodates a broad low-frequency band at 85 ${\mathrm{cm}}^{\mathrm{-}1}$, which softens with increasing temperature.

We deform spherical giant vesicles made of lipid bilayers, egg yolk phosphatidylcholine (EYPC), 1,2-dilaureoyl-sn-3-phosphatidylcholine (DLPC), l-palmitoyl-2-oleoyl-sn-3-phosphatidylcholine (POPC), and digalactosyldiacylglycerol (DGDG), into prolate ellipsoids of revolution by means of alternating electric fields. The lateral tensions stretching the vesicle membrane are calculated from the Maxwell stress tensor and the eccentricity of the ellipsoid. The apparent increase of membrane area with tension, being due to a flattening of thermal undulations, permits us to determine the bending rigidities. We obtain 2.47×${10}^{\mathrm{-}20}$ J for EYPC, 3.37×${10}^{\mathrm{-}20}$ J for DLPC, 2.46×${10}^{\mathrm{-}20}$ J for POPC, and 1.01×${10}^{\mathrm{-}20}$ J for DGDG, with errors of up to 20%. These values are slightly smaller than those reported to date for the same materials.

An underlying similarity in the mathematical structure between a problem in the physical sciences and a problem in the biological sciences is presented. An isomorphism is established between cluster distributions in physics and issues related to genetic diversity in biology as given by the Ewens sampling theory [Theor. Population Bio. 3, 87 (1972)]. Allelic or genetic diversity, as measured by the number and frequency of different alleles (gene types), has a correspondence with the size distribution of clusters in physics. The rate of mutation in genetics is shown to have its parallel in Richardson’s thermionic emission rate in physics. Using methods from combinatorial analysis and from the symmetric group ${\mathit{S}}_{\mathit{n}}$, simple formal connections between these two areas are developed. The logarithmic series of Fisher, Corbet, and Williams [J. Animal Ecol. 12, 42 (1943)] for species abundance appears in the solution developed as does a scale-invariant hyperbolic function. Maximum entropy methods are discussed. Even though the underlying dynamical processes are quite different in these two areas, new insights and the possibility that methods developed in one area may be used with advantage in the other area may follow from this correspondence.

This paper presents a discussion of thermodynamic properties of α-helix protein from the point of view of the statistical mechanics of a soliton on a one-dimensional chain. We prove that the Davydov solitons can satisfy the equation of motion of a ${\mathrm{\phi }}^4$ chain. We calculate the critical temperature and coefficient of linear specific heat of an α-helix protein and the results suggest Davydov solitons may indeed be biologically relevant.

The local expansion rate of nearby orbits on the critical golden torus is calculated from experimental data obtained in the Taconis oscillation system. The time series of an accumulated expansion rate has a self-similar structure characterized by the Fibonacci sequence. The self-similar structure can also be clearly seen in the power spectrum of the time series.

Non-mean-field-type excess correlations at short times are present in three-dimensional (3D) computer simulations of the velocity autocorrelation function, but absent in 1D, 2D, and 4D. They are caused by ring collisions in a quasi-3D slab of size 2×L×L×L in a face-centered-hypercubic lattice with periodic boundary conditions, which is the only available lattice-gas cellular automaton with 3D isotropic fluid flow. We evaluate this excess correlation. The simulation data agree very well with our exact result.

We report results of numerical simulations for a generalized monomer-dimer catalysis model on a Sierpinski gasket. We indicate the existence of a steady-state region, which is much thinner than in the case of the two-dimensional square lattice, although the shape of the phase diagram is the same. In the adsorption-limited case the critical exponents are in good agreement with those obtained for two dimensions. The critical dimension for the monomer-dimer catalysis model is inferred to be 1.

The transient diffusion-limited A+B→0, ${\mathit{A}}_0$=${\mathit{B}}_0$ annihilation on fractals is studied both via deterministic reaction-diffusion equations and via simulations of the stochastic many-particle problem. We show that the two approaches are not equivalent, yet the deterministic expressions capture the correct asymptotic behavior. For Sierpinski gaskets our analysis focuses on the overall decay law: ${\mathit{t}}^{\mathrm{-}\mathrm{\alpha }}$ with α=min(d̃/4,1) and on the superimposed hierarchical oscillations.

In this paper we study the gaps between domains of segregated particles in the transient A+B→0 reaction in fractals. Using a scaling analysis we show that the average gap grows as ${\mathit{t}}^{\mathrm{\zeta }}$ with ζ=[1+(${\mathit{d}}_{\mathit{s}}$/4)-1/${\mathit{d}}_{\mathit{w}}$]/(${\mathit{d}}_{\mathit{f}}$+${\mathit{d}}_{\mathit{w}}$-1), for ${\mathit{d}}_{\mathit{s}}$≤2. We propose a method for the numerical calculation of the gaps and apply it to Euclidean lattices and to Sierpinksi gaskets. We also present numerical results on the average nearest-neighbor distance between like particles; these follow the scaling law ${\mathit{t}}_{\mathit{A}\mathit{A}}^{\mathrm{\alpha }}$ with ${\mathrm{\alpha }}_{\mathit{A}\mathit{A}}$=${\mathit{d}}_{\mathit{s}}$/(4${\mathit{d}}_{\mathit{f}}$). All results are consistent with the power-law density decay being characterized by the exponent min(${\mathit{d}}_{\mathit{s}}$/4,1).

A representation of the oscillators for infinite statistics in terms of bosons is given. The relation to the Susskind-Glogower operator is also discussed.

Two theoretical equations of state are compared with each other and with Monte Carlo calculations for inverse-power potentials. The hard-sphere perturbation theory is accurate at low densities for all potentials and at high densities for hard potentials, but is poor for soft potentials at high densities. The theory motivated by one-component-plasma results is accurate only at high densities and is quite accurate for soft potentials.

Results of recent experiments on the Rayleigh-Bénard system indicate that stochastic driving forces are important in the evolution of flow patterns. However, the strength of the noise needed to reproduce the experimental results is four orders of magnitude larger than that of thermal noise. In this report, we present evidence that suggests that the source of noise comes from an uncertainty in the initial conditions rather than from a stochastic driving force.

We study experimentally the convective instability in a layer of helium I subject to a time-dependent rotation about a vertical axis Ω(t)=${\mathrm{\Omega }}_{\mathit{s}}$+${\mathrm{\Omega }}_0$cos(ω̃t). Relative stability of the conducting state is primarily determined by ω̃, with the magnitude of shifts in the convective threshold at fixed ω̃ increasing with the modulation amplitude ${\mathrm{\Omega }}_0$/${\mathrm{\Omega }}_{\mathit{s}}$. Our observations are compared with recent theoretical work.