We present measurements of the curve of $f \mathrm{vs} \alpha$ from two-dimensional sections of the "dissipation" field of concentration fluctuations, and from one-dimensional sections of the dissipation field of passive temperature fluctuations, in turbulent jets. The results confirm the universality of the dissipation rate $\chi$ of scalar fluctuations and the applicability of Taylor's hypothesis, and show that the curve of $f \mathrm{vs} \alpha$ is the same for different components of $\chi$, that the additive properties of $f\left(\alpha \right)$ apply to intersections, and that the intermittency exponent of $\chi$ is considerably higher than that for the turbulent kinetic-energy dissipation.

From measurements of the convective heat transport in a normal ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixture over the range $-0.018\mathrm{}\lesssim \psi \lesssim 0.015$ of the separation ratio $\psi$, we found a time-periodic state for $\psi <{\psi }_{\mathrm{CT}}=-0.0044\mathrm{}$. The dimensionless onset frequency at ${\psi }_{\mathrm{CT}}$ was 1.42, much larger than the value predicted by linear-stability analysis for a spatially uniform, laterally infinite system. For ${\psi }_{\mathrm{CT}}>\psi >{\psi }_c\approx -0.010\mathrm{}$ the bifurcation to oscillations was forward while for $\psi \lesssim {\psi }_c$ it was backward. The results suggests that ${\psi }_c$ is an additional codimension-two point, rather than a Hopf tricritical point.

The wave experiment of the Viking satellite frequently detected dynamic small-scale (≃ 100 m), large-amplitude, rarefactive ($\left|\frac{\Delta n}{n}\right|\lesssim 50\%$) solitary waves of negative potential ($\left|\phi \right|\lesssim 2$ V) moving upwards along the magnetic field lines ($\upsilon =5\mathrm{} \mathrm{to} >50\mathrm{}$ km/s). The structures, which resemble ion holes, often have an upward-directed net potential drop (≲ 1 V) and are then interpreted as weak double layers.

A technique is proposed for extraction of the electron ring from the modified betatron accelerator. Basically, this technique consists of exciting the resonance that naturally exists for some specific values of the ratio of the vertical to toroidal magnetic field.

The maximum amplitude of relativistic plasma oscillations (${\upsilon }_{\mathrm{ph}}$ near $c$) is obtained with a combined one-dimensional waterbag and warm-fluid model. The waterbag description is used to obtain expressions for the pressure and internal energy as functions of the proper density. A relativistic Euler's equation that is valid for arbitrarily large amplitudes and an analytic expression for the wave-breaking amplitude in the limit ${\upsilon }_{\mathrm{ph}}\cong c$ are obtained. Even a small amount of thermal energy can significantly reduce the maximum plasma-wave amplitude relative to the cold wave-breaking value. The significance of the results for recent accelerator schemes is discussed.

It is shown that high-kinetic-$\beta$ neutralized ion beams with transverse width less than an ion gyroradius and density larger than the background plasma density can propagate uninhibited through a magnetized plasma over many ion gyroradii. The model is confirmed by computer simulations using a two-dimensional hybrid code.

We report the first experimental test of the physics of plasma wake-field acceleration performed at the Argonne National Laboratory Advanced Accelerator Test Facility. Megavolt-per-meter plasma wake fields are excited by a intense 21-MeV, multipiscosecond bunch of electrons in a plasma of density $n_e\simeq {10}^{13}$ ${\mathrm{cm}}^{-3\mathrm{}}$, and probed by a low-intensity 15-MeV witness pulse with a variable delay time behind the intense bunch. Accelerating and deflecting wake-field measurements are presented, and the results compared to theoretical predictions.

A theory of self-diffusion in concentrated dispersions is presented, in which the effects of hydrodynamic and direct interactions between macroparticles are virtually decoupled. The long-time self-diffusion coefficient $D_s^L$ is written in terms of the radial distribution function of the suspended particles and of their short-time self-diffusion coefficient $D_s^S$. The predictions for the volume fraction dependence of $D_s^L$ in hard-sphere suspensions are in excellent agreement with available experimental results.

For a general isotropic two-dimensional theory near criticality, the universal singular free energy per correlation volume $f_s{\xi }^2$ is equal to $-\left(\frac{c}{12}\pi \right)(2-\alpha ){(1-\alpha )}^{-1\mathrm{}}$, where $c$ is the central charge of the theory at criticality, $\alpha$ is the usual specific-heat exponent, and $\xi$ is defined (for $\alpha >0\mathrm{}$) in terms of the second moment of the energy correlations. Some generalizations of this result are also noted.

We present a theory to study external non-Markovian noise in diffusion processes by using the multistate continuous-time random walk. We show that if the external noise is anomalous the effective Green's function of the walker has no long-time tails. We study the internal fluctuations in presence of non-Markovian noise.

The statistical hypothesis underlying the "strange attractor" explanation of fluid turbulence is suspect. Spatially extended systems generically exhibit long transients that preclude observation of the behavior governed by the asymptotic invariant measure. Even if the local dynamics is periodic, when it is coupled into a spatial system complex "turbulent" behavior can exist for times that grow faster than exponentially with increasing system volume. The nature of the attractor is irrelevant to the observed behavior when such systems are of even moderate size.

We present measurements of the phase diagram for a nonlinear electronic oscillator circuit which has three intrinsic frequencies. The persistence of chaos to almost zero intermode coupling and the measured structure of the chaotic zones in parameter space provide unprecedented detail in the interpretation of the Ruelle-Takens scenario for the onset of chaos.

We investigate the utility of the $K^{+}$ meson as a probe of effective-size modifications ("swelling") of nucleons in the nuclear medium. The $K^{+}$-nucleus elastic and total cross sections are found to be sensitive to the density-dependent effective masses of the vector mesons ($\rho ,\omega$) whose exchange is responsible for the dominant part of the low-energy $K^{+}$-nucleon interaction. This density dependence is estimated in several ways and used to construct a $K^{+}$-nucleus optical potential. Such a model is consistent with the $K^{+}+{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ data at 800 Mev/c, and provides a physical picture of the "swelling" mechanism in terms of the medium modifications of the meson cloud of the nucleon.

The evolution of both the sudden and adiabatic polarization energies resulting from a rare gas interacting with a dopant ion was followed for the first time. The variation of these two polarization energies was determined by means of photoabsorption and photoionization up to rare-gas number densities of (23.0, 24.0, 11.3, and 6.6)×${10}^{20}$ ${\mathrm{cm}}^{-3\mathrm{}}$ for He, Ne, Ar, and Kr, respectively. Both polarization energies were found to vary linearly with rare-gas number density. However, the slopes differ by more than 1 order of magnitude. This difference is explained in terms of a model which accounts for the different time scales of the two experiments.

The squeezing spectrum for nondegenerate parametric oscillation above threshold is calculated, including phase diffusion. A nonclassical correlation in phase and intensity occurs which is an example of the Einstein-Podolsky-Rosen paradox, even in fields of large photon number.

It is shown experimentally that the orientation dependence of nuclear magnetic dipole-dipole couplings in high-field NMR can be removed by rapid rotation of the sample and application of a synchronized rf pulse sequence. The sample rotation and rf pulses coherently average the usual truncated, high-field couplings to the form of untruncated, zero-field couplings. The resulting NMR spectra of polycrystalline solids show sharp lines with splittings that depend only on internuclear distances, rather than the usual broad powder-pattern lines. The derivation of the pulse sequence is described.

The mechanisms of two-dimensional turbulence are investigated by means of a very high-resolution lattice-gas simulation. The results from this simulation are quantitatively compared with the direct integration of the Navier-Stokes equation. The dissipation of the flow simulated by the lattice gas is estimated by a simple scaling argument on the microscopic noisy field of the automaton.

A reversible structural transition from (1 × 1) to (2 × 1) is observed for 2-monolayer (ML) Fe films deposited on Cu(100) when the substrate is cooled to temperatures below 300 K. The disperson of the Rayleigh wave displays a pronounced anomaly indicative of a repulsive stress in the Fe film. The phase transition for the 2-ML system, irreversible order-disorder transitions for the 4- and 5-ML systems, and the termination of the epitaxial layer-by-layer growth beyond 5 ML may be understood in terms of the repulsive stress between the Fe atoms.

The assumption of the scaling law, that the monomer structure remains constant as the polymer concentration changes from the dilute to semidilute regime, has been tested by use of optical second-harmonic generation. The monomer orientation does not change as the polymer concentration is increased. This observation is the first confirmation of the basic assumption of the scaling law which describes polymer behavior in two-dimensional space.

Critical interfacial tension amplitudes can be obtained without the usual difficult task of calculating the related excess free energy. This permits for the first time practical Monte Carlo calculations with very large lattices. By use of up to 128 × 128 × 128 for the simple-cubic Ising model, a new amplitude is obtained and is larger than previous estimates with smaller lattices. This resolves the long-standing large disagreements between experiments and theory on the universality of the related amplitude ratios.