A new simple and rapid method to determine pore size distributions is described which employs a simple nuclear magnetic resonance (NMR) apparatus. The method exploits the depression of the melting point of a crystalline solid confined within a pore, which is dependent on the pore diameter. The melting point distribution is determined by analyzing the NMR signal as a function of temperature. The technique is demonstrated by application to porous silicas and is shown to give pore size distributions comparable to those obtained by the conventional gas desorption method for pore sizes in the range 5 to 50 nm.

We study the kinetics of the reaction front for diffusion-reaction systems of the form A+B→C which are confined to one dimension, and in which the reactants are initially separated. For the case in which both A and B diffuse, the spatial moments of the reaction front are characterized by a hierarchy of exponents, bounded by the exponents, σ=1/4 and δ=3/8 characterizing the asymptotic time dependence of the distance ${\mathit{l}}_{\mathit{A}\mathit{B}}$(t) between nearest neighbor A and B particles and the fluctuations of the midpoint m(t) between them, respectively. We argue that this behavior arises from confinement effects and will appear in other confined systems.

The unbinding of N membranes interacting with attractive potentials is considered theoretically for zero pressure. In the symmetric case, for which the membranes have the same bending rigidity, all N membranes unbind simultaneously at the N-independent temperature ${\mathit{T}}_{\mathit{c}}^{\mathit{s}}$ but with N-dependent effective critial exponents. In the asymmetric case, for which the lowest membrane acts as a rigid wall, they exhibit a sequence of unbinding transitions with universal exponents; the transition temperature of the uppermost membrane for a semi-infinite stack (N=∞) is again given by ${\mathit{T}}_{\mathit{c}}^{\mathit{s}}$.

Large water soluble macromolecules can be confined in all proportions into an electrostatically stabilized surfactant lamellar phase without change of the bilayer thickness. Upon progressive addition of salt, the sample phase separates into a polymer-rich and a surfactant-rich lamellar phase. Indeed, at some particular salt concentration, the intermembrane repulsive interaction is no longer sufficient to maintain the polymer coils squeezed into the lamellar structure. The phase separation is generally first order. But we could find a situation where it becomes second order.

We study a simple 2D dynamical model of a tectonic plate with long range elastic forces and quenched disorder. The interplay between long-range elasticity, threshold dynamics, and the quenched featureless small-scale heterogeneity allows us to capture both the spontaneous formation of fractal fault structures by repeated earthquakes and a short-time spatiotemporal chaotic dynamics of earthquakes, well-described by a Gutenberg-Richter power law. Faults are mapped onto a minimal interface problem, which in 2D correponds to the random directed polymer problem and are thus self-affine with a roughness exponent 2/3.

Temporal Bell inequalities can be violated for sequences of events (histories) for which probabilities satisfying consistent sum rules cannot be defined. We discuss possible experiments in which such violations, never observed so far, may indeed be seen. The basic scheme, which uses three optically driven and mutually interacting two-level systems, could be implemented in a variety of nanostructures. It could even be mapped onto the dynamics of a single electron four-level system thus allowing for a realization in atomic physics.

We consider generalized commutation relations in a dynamically evolving curved spacetime which, prior to some initial time and subsequent to some later time, is flat. By considering the Bogoliubov transformations associated with gravitationally induced particle creation, we find that the consistent evolution of the generalized commutation relations from the first flat region to the second flat region can only occur if q=±1.

We study the gravitational dressing of renormalizable two-dimensional field theories. Our main result is that the one-loop β function is finitely renormalized by the factor (k+2)/(k+1), where k is the central charge of the gravitational SL(2,R) current algebra.

The interaction of spins in a spin-polarized test mass and those in a paramagentic salt, separated by a μ-metal shield and a double-layer superconducting shield, was investigated. Our results set a limit on electron spin interactions and on moments which are not of electromagnetic origin. In terms of a standard dipole-dipole form, the limit is (2.7±2.4)×${10}^{\mathrm{-}14}$ of the interaction strength between the magnetic moments of the electrons. Compared to previous results, this is more than a twentyfold improvement.

An expression for the lattice efective action induced by chiral fermions in any even dimensions in terms of an overlap of two states is shown to have promising properties in two dimensions: The correct Abelian anomaly is reproduced and instantons are suppressed.

We have measured branching ratios for three ${\mathrm{\Lambda }}_{\mathit{c}}$ decay modes that have a ${\mathrm{\Sigma }}^{+}$ in the final state. Two of the observed decay modes, ${\mathrm{\Lambda }}_{\mathit{c}}$→${\mathrm{\Sigma }}^{+}$${\mathrm{\pi }}^0$ and ${\mathrm{\Lambda }}_{\mathit{c}}^{+}$→${\mathrm{\Sigma }}^{+}$ω, have no external W-emission amplitudes. Their branching ratios relative to the ${\mathit{pK}}^{\mathrm{-}}$${\mathrm{\pi }}^{+}$ mode are 0.20±0.03±0.03 and 0.54±0.13±0.06, respectively. We have also significantly improved the measurement of the branching ratio for the previously observed decay mode ${\mathrm{\Lambda }}_{\mathit{c}}^{+}$→${\mathrm{\Sigma }}^{+}$${\mathrm{\pi }}^{+}$${\mathrm{\pi }}^{\mathrm{-}}$. We find its branching ratio relative to ${\mathit{pK}}^{\mathrm{-}}$${\mathrm{\pi }}^{+}$ to be 0.74±0.07±0.09.

We observe the ${\mathrm{\Sigma }}_{\mathit{c}}^{+}$ baryon decaying to ${\mathrm{\Lambda }}_{\mathit{c}}^{+}$${\mathrm{\pi }}^0$ and measure the mass difference M(${\mathrm{\Sigma }}_{\mathit{c}}^{+}$)-M(${\mathrm{\Lambda }}_{\mathit{c}}^{+}$) to be 168.5±0.2 MeV/${\mathit{c}}^2$. We also measure the mass differences M(${\mathrm{\Sigma }}_{\mathit{c}}^{++}$)-M(${\mathrm{\Lambda }}_{\mathit{c}}^{+}$) and M(${\mathrm{\Sigma }}_{\mathit{c}}^0$-M(${\mathrm{\Lambda }}_{\mathit{c}}^{+}$) with improved precision and determine the isospin mass splittings M(${\mathrm{\Sigma }}_{\mathit{c}}^{++}$)-M(${\mathrm{\Sigma }}_{\mathit{c}}^0$) and M(${\mathrm{\Sigma }}_{\mathit{c}}^{+}$)-M(${\mathrm{\Sigma }}_{\mathit{c}}^0$) to be 1.1±0.4±0.1 MeV/${\mathit{c}}^2$ and 1.4±0.5±0.3 MeV/${\mathit{c}}^2$, respectively. Our results indicate that the light quark mass difference does not dominate the isospin mass splitting in ${\mathrm{\Sigma }}_{\mathit{c}}$.

We study the stabilization behavior of the circular 5g state in neon in a two-pulse experiment. A first pulse prepares the state. Comparison of the single-photon ionization yield, due to a second laser pulse for both short (0.1 ps) intense and long (1 ps) less intense pulses shows an intensity-dependent suppression of ionization. The smaller yield due to the short pulses at intensities of several times ${10}^{13}$ W/${\mathrm{cm}}^2$ is in accordance with recent predictions of stabilization.

The vibrational excitation of ${\mathrm{N}}_2$ molecules adsorbed on a silver surface by low energy electron impact is studied within the newly developed coupled angular mode method. The process involves the formation of a transient negative molecular ion. The results account well for the observations of Demuth and co-workers. They also reveal that most of the vibrational excitation corresponds to electrons scattered into the metal and thus unobservable in a scattering experiment.

We study an ensemble of N bosonic atoms coupled by dipole-dipole interaction and also interacting with an electromagnetic field. Effective single-atom nonlinear Schrödinger equations are derived. The implications of these equations are discussed in the context of some standard atom optics geometries, illustrating in particular how many-body effects modify the Pendellösung of Bragg scattering. In another regime, the problem is reduced to a classical massive Thirring model, with the possibility of generating atomic Thirring solitons.

A new type of optical soliton is presented for two-wave interactions in quadratic nonlinear media. Unlike the conventional soliton in cubic nonlinear media, the most unique feature of the present solitons is found in the feasibility of multidimensional confinement. A compact analytical expression for the new solitons with arbitrary transverse dimension is derived through the self-consistent-field approximation. With available nonlinear materials in mind, a specific method for observing the multidimensional solitons is investigated.

Wavelet cross spectra and cross scalograms are used to analyze the time-scale structure of bivariate turbulence data from the boundary layer over the ocean. The cross scalogram for the streamwise and vertical turbulent velocity components shows a highly intermittent pattern with significant contributions of opposite signs appearing at two specific scales, ∼60 m and ∼2 km, believed to be related to small-scale turbulent mixing and large-scale secondary flow in the boundary layer.

Among the very rich range of possibilities for the dynamics of one dimensional fronts, this article presents, in a film draining experiment, the first observation of a continuous transition from solitary waves to a static spatially periodic pattern. Between these two extreme situations, a regime of colliding solitary waves exhibiting chaos with spatiotemporal intermittency is observed. These observations suggest the description of the static periodic pattern as being the result of a dense packing of propagating solitary waves, and its destabilization to spatiotemporal intermittency as the attempt of some solitary waves to propagate.

A pattern of standing surface waves in the form of equilateral triangles is observed in the Faraday experiment with two-frequency forcing. By perturbing with a third frequency the dynamics of a ‘‘phason mode’’ is under external control and transitions between triangles and hexagons can be enforced. The experiment is understood in terms of a three-mode amplitude equation model.

Experimental studies of the source dynamics of counterpropagating waves in a convecting binary fluid are presented. The source motion is controlled by side heating. There exists a locking band inside which the source is pinned by the underlying roll structure. Outside this band the source commences to move abruptly by steps of half a wavelength. A distortion of the phase field and the resulting nonlinear flow are essential ingredients responsible for the abrupt transition to the sliding state. Strong similarity to switching charge density waves dynamics is discussed.