An unprecedented microgravity observation of maximal shape oscillations of a surfactant-bearing water drop the size of a ping-pong ball was observed during a mission of Space Shuttle Columbia. The goal of the research, of which this observation is a part, was to study the rheological properties of liquid drop surfaces on which are adsorbed surfactant molecules under conditions not possible at 1g. Numerical computation of the evolution of the shape of greatly deformed drops using the boundary integral method has successfully predicted the observed drop shapes over a complete cycle of oscillation, thereby permitting the calculation of the dynamic surface tension under these unique conditions.

A phase model of rings of coupled oscillators is proposed and shown to exhibit a peculiar type of wave. As a parameter is varied, such waves are born with a characteristic pattern and then develop into complex waves such that phase differences between neighboring oscillators are spatially “chaotic,” showing type-3 intermittency. Their behavior is studied on the basis of a multivalued one-dimensional map obeyed by the phase differences.

We show that the number of KLD (Karhunen-Loève decomposition) modes $D_{\mathrm{KLD}}$ needed to capture a fraction $f$ of the total variance of an extensively chaotic state scales extensively with subsystem volume $V$. This allows a correlation length ${\xi }_{\mathrm{KLD}}$ to be defined that is easily calculated from spatially localized data. We show that ${\xi }_{\mathrm{KLD}}$ has a parametric dependence similar to that of the dimension correlation length and demonstrate that this length can be used to characterize high-dimensional inhomogeneous spatiotemporal chaos.

We consider the motion of a damped particle in a potential oscillating slowly between a simple and a double well. The system displays hysteresis effects which can be of a periodic or chaotic type. We explain this behavior by computing an analytic expression of a Poincaré map.

Results are presented for the kinetics of domain growth of a two-dimensional fluid quenched from a disordered to a lamellar phase. At early times when a Lifshitz-Slyozov mechanism is operative the growth process proceeds logarithmically in time to a frozen state with locked-in defects. However, when hydrodynamic modes become important, or the fluid is subjected to shear, the frustration of the system is alleviated and the size and orientation of the lamellae attain their equilibrium values.

A Comment on the Letter by C. Van den Broeck, J. M. R. Parrondo, and R. Toral, Phys. Rev. Lett. 73, 3395 (1994). The authors of the Letter offer a Reply.

A Reply to the Comment by Seunghwan Kim, Seon Hee Park, and Chang Su Ryu.

Frequency analysis is used to chart the global phase space structure for the most general case of an electron bound by Coulombic and harmonic potentials and perturbed by tilted electric and magnetic fields. Distinct order-chaos transitions are found together with an example of a wave function scarred by a 3D “exotic” periodic orbit, thereby providing compelling evidence for the power of frequency analysis in studying multidimensional chaos.

We study the level spacing statistics $p\left(s\right)$ and eigenfunction properties in a billiard with a rough boundary. Quantum effects lead to localization of classical diffusion in the angular momentum space and the Shnirelman peak in $p\left(s\right)$ at small $s$. The ergodic regime with Wigner-Dyson statistics is identified as a function of roughness. Applications to $Q$ spoiling in optical resonators are also discussed.

The fragment mass distributions of platelike objects are investigated by conducting two types of experiments. The first is a “sandwich” experiment in which thin glass and plaster plates are inserted between two larger stainless steel plates and an iron projectile is dropped onto the target plate at normal incidence. The second is a “lateral impact” experiment in which a hypervelocity nylon projectile collides at the side of the plaster plates. There is a discrepancy in the power-law exponent of fragment mass distribution between the sandwich experiment and the lateral impact experiment. A model that agrees with the experimental results is proposed.

Experimental evidence of superlubricity, the state of vanishing friction, is obtained by examining systems of sliding atomically clean surfaces by using ultrahigh vacuum scanning tunneling microscopy. The experimental results agree with theoretical predictions: Friction is not observed in the superlubricity regime in measurements capable of resolving a friction force of $3\times {10}^{-9\mathrm{}}\mathrm{N}$, whereas friction of $8\times {10}^{-8\mathrm{}}\mathrm{N}$, which is comparable to theoretical values, is observed in the friction regime.

We consider the tails of probability density function (PDF) for the velocity that satisfies Burgers equation driven by a Gaussian large-scale force. The saddle-point approximation is employed in the path integral so that the calculation of the PDF tails boils down to finding the special field-force configuration (instanton) that realizes the extremum of probability. For the PDFs of velocity and its derivatives $u^{\left(k\right)}={\partial }_x^{k}u$, the general formula is found: $\ln P\left(|u^{\left(k\right)}|\right)\propto -(|u^{\left(k\right)}|/{\mathrm{Re}}^k{)}^{3/(k+1\mathrm{})}$.

We consider numerical solutions to a shell model of decaying homogeneous isotropic turbulence with helicity. In phase space, the stable manifold of the Komolgorov equilibrium has zero helicity in all shells. Trajectories starting near the stable manifold miss the equilibrium and enter a chaotic regime. Exponential growth of the helicity characterizes the divergence from the equilibrium. Erratic fluctuations of helicity and dissipation follow. As a result the energy decays intermittently. At high ${\mathrm{Re}}_{\lambda }$ the energy decay is an irregular staircase descending roughly as $E\propto t^{-1\mathrm{}}$.

We report experimental observation of a localized structure, which is of a new type for dissipative systems. It appears as a solitary vortex pair (“diwhirl”) in Couette flow with highly elastic polymer solutions. In contrast to the usual solitons the diwhirls are stationary. It is also a new object in fluid dynamics—a pair of vortices that build a single entity. The diwhirls arise as a result of a purely elastic instability through a hysteretic transition at negligible Reynolds numbers. It is suggested that the vortex flow is driven by the same forces that cause the Weissenberg effect.

A Comment on the Letter by Tsuyoshi Hondou and Yasuji Sawada Phys. Rev. Lett. 75, 3269 (95).

A method, based on fundamental properties of chaotic dynamics, is devised for filtering in-band noise of an incoming signal generated by a chaotic oscillator. Initially the $2x$ mod 1 map is used to illustrate the procedure and then the method is applied to recover the message encoded in a realistic chaotic signal, after the transmitted signal has been contaminated with noise.

High-harmonic generation with excitation pulses shorter than 25 fs is studied theoretically using a 3D model. For very short excitation pulses, a new regime of harmonic generation by a “single-cycle” of the driver pulse can be reached. In this regime, the temporal coherence of the adjacent harmonic orders is dramatically improved compared with longer excitation pulses, even though the discrete harmonic structure in the emission disappears. X-ray pulses as short as 100 attoseconds can be emitted, with increased conversion efficiency of laser-to-harmonic radiation.

We report experiments on the rise time T of a single large sphere within a sinusoidally vibrated bed (amplitude a) of uniform particles (diameter d). At fixed acceleration, we identify three distinct behavioral regimes both from visual observations and from the typical increase of T with frequency f. We observe two convective regimes separated by a critical frequency and, for low a and high f, a “nonconvective” regime. In the latter, the bed crystallizes and a size dependent rise is evidenced. We show the relevance of the nondimensional parameter $a/d$ and deduce a scaling law of the form $f\propto d^{-1/2\mathrm{}}$.

We propose a mechanism for the previously unexplained formation of spanwise cells observed in the vortex street wake of finite-length cylindrical bluff bodies at low Reynolds numbers. It involves the spatial growth of the secondary Eckhaus instability of oblique vortex shedding, controlled by end effects, and leads to a new interpretation of observed wake frequency relations. Predictions of cell size variations and wake patterns are obtained from the phenomenological Ginzburg-Landau model, and good agreement is found with experimental observations.

A Comment on the Letter by Weiming Yang, E-Jiang Ding and Mingzhou Ding, Phys. Rev. Lett. 76, 1808 (1996).