Anomalous pump-depletion reversal in stimulated Raman scattering has been observed and is interpreted as the development of a soliton induced by a random phase shift in the injected Stokes beam. The experimental findings are presented and compared with the analytical solutions to the undamped stimulated Raman scattering equations as well as with a numerical study of the damped equations.

A collection of $N$ Rydberg atoms and a resonant millimeter-wave cavity are shown to exchange energy back and forth at a rate $2\left(\frac{d}{\hslash }\right){\mathcal{E}}_0\sqrt{N}$, where $d$ is the electric dipole matrix element of the atomic transition and ${\mathcal{E}}_0$ the "field per photon" in the cavity. This experiment is a demonstration of self-induced Rabi oscillations in a two-level atom system coupled to a single electromagnetic field mode and can also be considered as a very simple illustration of "ringings" in superradiant emission.

Conditions suitable for the adiabatic electron-ion two-stream instability have been created in a toroidal plasma. Observed anomalous resistivity, turbulent heating rates, and ion plasma oscillations are in favorable agreement with the recent theoretical predictions.

This Letter reports the first experimental evidence that solutions of linear flexible polymers are characterized by a concentration-dependent universal length which is easily scaled to be independent of molecular weight $M(3\mathrm{}\times {10}^5<~M<~2.6\times {10}^7)$ and of solvent quality. It is also found that the product of $M$ and the derivative of the osmotic pressure $\pi$ with respect to concentration $c$, $M{\left(\frac{\partial \pi }{\partial c}\right)}_T$, is universal and independent of solvent quality or $M$.

The presence is shown of narrow early-transition-metal $d$ bands in the unoccupied states, sometimes several electronvolts above the occupied states, in alloys of early with late transition metals. The widths of these states are small if the early-transition-metal concentration and the host density of states above $E_{\mathrm{F}}$ are both low. Their relationship to the narrow resonances of impurities in metals and their possible relevance to optical properties are discussed.

The carbon-carbon bond lengths in polyacetylene have been directly measured with use of nutation NMR spectroscopy. 1.36 and 1.44 Å were found for the double and single bonds, respectively, in trans-${\left(\mathrm{CH}\right)}_x$, and 1.37 Å was found for the double bond in the cis isomer. Over the temperature range 4.2-300 K, the dynamical single-double bond interchange predicted for chains in trans-${\left(\mathrm{CH}\right)}_x$ containing a mobile soliton defect was not observed.

The Faraday rotation and spontaneous Hall effect were investigated in amorphous thin films with compositions ${\left(\mathrm{GdFe}\right)}_{1-x}{M}_x$ ($M=\mathrm{B}\mathrm{i},\mathrm{S}\mathrm{n},\mathrm{A}\mathrm{u}$). Bismuth and tin are found to increase the Faraday rotation, ${\varphi }_{\mathrm{F}}$, the Hall resistivity, ${\rho }_{\mathrm{H}}$, and the sample resistivity, $\rho$, while Au decreases ${\varphi }_{\mathrm{F}}$, ${\rho }_{\mathrm{H}}$, and $\rho$ as compared to values observed for GdFe. Specifically, ${\varphi }_{\mathrm{F}}$ is proportional to the Hall angle ($\frac{{\rho }_{\mathrm{H}}}{\rho }$). A model first proposed by Voigt is developed to account for this proportionality.

Tight-binding models in one dimension with incommensurate potentials are studied. For the sinusoidal-potential model scaling of the spectrum is found numerically at the critical point, which separates the region where all the states are extended and the region where all the states are localized. Absence of scaling for generic potentials indicates the existence of mobility edges. An index $\delta$, which characterizes the behavior of the total width of allowed energies, is defined at the critical point. For a class of discontinuous potentials, the systems are found to be always critical.

By combining the Emin-Holstein scaling theory of polaron formation with the scaling theory of localization in disordered systems, the authors show that the nonuniform extended eigenstates above the mobility edge (responsible for the continuous drop of the mobility to zero) collapse to localized polarons as the electron-phonon interaction is turned on.

The recent interpretation of Parisi's order-parameter function $q\left(x\right)\mathrm{}$ in terms of a probability distribution for the overlap between magnetizations in different phases is investigated by Monte Carlo computer simulation for the infinite-range Ising spin-glass model. The main features of the solution for $q\left(x\right)\mathrm{}$ are reproduced, in particular $q\mathrm{}\left(x\right)\mathrm{}\propto x$ as $x\to 0$ and $q^{\prime }\mathrm{}\left(x\right)=0\mathrm{}$ at $q=q_{max}$, the largest value. Finite-size effects prevent one from establishing with certainty whether there is a "plateau," i.e., $q^{\prime }\mathrm{}\left(x\right)=0\mathrm{}$ for a range of $x$.

The Ising model, with equivalent-neighbor and nearest-neighbor interactions of Cayley-tree connectivity, is solved exactly. Breaking translational symmetry by turning on the Cayley interactions is analogous to lowering spatial dimensionality in Bravais lattices. A range of classical criticality, a point of logarithmic corrections, a range of continuously varying power-law singularities, and a point of exponential singularity are successively encountered.

Microwaves near 42 GHz are found to influence the growth of Saccharomyces cerevisiae. The growth is measured photometrically in stirred aqueous culture. The microwave effect occurs and saturates above a threshold intensity < 10 mW/${\mathrm{cm}}^2$, excluding any explanation based on microwave heating. A surprisingly strong frequency dependence is observed, with resonances as narrow as 8 MHz. These results confirm the existence of a nonthermal resonant microwave sensitivity in biology; they suggest yet unknown tuned systems triggering yet unknown biological actions.

It is proposed that the acceleration of cosmic rays is distributed over their propagation through interstellar space. Thus after most nuclear fragmentation reactions in the interstellar medium, cosmic rays gain about a factor of 5 in energy. This hypothesis resolves several discrepancies in composition at different energies. The present results suggest that after the principal acceleration and during their galactic confinement, cosmic rays are further accelerated by the weak shocks of widely distributed old supernova remnants.

Inverting the spin state of one of the two coherent waves propagating within a neutron interferometer by means of a radio-frequency spin-flip device leads to a nonstationary interference pattern. By using stroboscopic neutron detection one can resolve this to demonstrate the nonclassical behavior of spinor superposition.

The evolution of the orbit of a binary pulsar under the action of gravitational radiation reaction is calculated. No approximation is made of weak gravity inside the individual stars; the details of the orbital motion are given directly (to order $c^{-5\mathrm{}}$ and $G^3$). The calculation reveals no acceleration of the center of mass of the system, and a secular decrease of the time of return to periastron. The quantitative results agree both with the well-known "quadrupole formula" and with observations.

From a sample of hadronic events produced in $e^{+}{e}^{-}$ collisions, semileptonic decays of heavy particles have been isolated and used to obtain a measurement for the bottom-quark lifetime of [1.8±0.6 (stat.)±0.4(syst.)]×${10}^{-12\mathrm{}}$ sec.

It is shown that instantons generate a superpotential in supersymmetric QCD with $N$ colors and $N-1\mathrm{}$ flavors.

For a wide range of masses of the $W$ superpartners and the supersymmetric scalars it is shown that a measurement of the total electron-positron annihilation cross section is sufficient to demonstrate the existence or nonexistence of supersymmetry.

Atomic effects on the tritium $\mathrm{ft}$ value including bound-state decay, imperfect wave-function overlap, screening, and electron exchange are considered for each of the species ${\mathrm{T}}^{+}$, T, ${\mathrm{T}}_2$, and ${\mathrm{T}}^{-}$. Corrections to the $f$ value are tabulated and can be combined to extract an improved estimate for the axial-vector matrix element in tritium $\beta$ decay.

Ths isoscalar giant quadrupole resonance is studied in ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}({\pi }^{\pm },{\pi }^{\pm \prime })$ at 130 MeV. It is found that the ratio of ${\pi }^{-}$ to ${\pi }^{+}$ cross sections at their maximum is 1.9 and that 57% of the energy-weighted sum rule is exhausted in ${\pi }^{-}$ scattering. This large ratio of ${\pi }^{-}$ to ${\pi }^{+}$ cross sections is not anticipated by conventional models, and may be interpreted as evidence for substantial isovector strength.