It is shown that the insulating oxide ${\mathrm{Fe}}_2$Ti${\mathrm{O}}_5$ exhibits anisotropic (uniaxial) spin-glass behavior below 55 K. Extensive experimental results supporting this conclusion, including principal magnetic susceptibility, neutron scattering, ultrasonic, specific heat, and oriented single-crystal Mössbauer measurements, are described.

It is shown that electron tunneling in mechanically contacted high-speed submicron junction occurs in the presence of tens of kilobars of local stress. The observations are made under highly controlled conditions. Sharp tunneling resonances originating from a band-structure effect related to Ni ferromagnetism are observed and their stress and magnetic shifts studied.

With large surface-sensitivity enhancement achieved by use of $p$-polarized light, soft-x-ray photoemission spectra of $4f$ core levels from the outermost atoms of the (110) face of tungsten have been observed. High-resolution spectra show two well-separated $4f$ lines split by 0.30 eV, with the low-binding-energy peak being assigned to surface atoms. The ratio of the intensity of the surface peak to the bulk peak as a function of photon energy exhibits striking features which are tentatively explained.

A thermal gradient in a current-carrying superconductor gives rise to a branch imbalance and hence to a potential difference between quasiparticles and condensate. We present a theory of this effect valid for a dirty and for a clean superconductor which is in good agreement with recent experiments.

Measurements of the electrical resistivity of palladium, residual resistivity ratio ∼22 500, containing 1.7 ppm of Fe have been made from 5.5 K to 1.8 mK. 15 Hz ac susceptibility measurements from 1 K to 1.8 mK together with the resistivity data suggest that a transition into a spin-glass state occurs near 7 mK.

We have used the Monte Carlo renormalization-group method to study the three-state Potts model in three and four dimensions. In both cases, we find a first-order transition without an associated discontinuity fixed point. The transition in three dimensions is "almost second order" in the sense that some evidence was found for the existence of second-order fixed points associated with singularities in the metastable region just beyond the first-order transition.

In the presence of long-time memory effects, Fick's law must be modified by replacing the diffusion coefficient by a convolution over time of the velocity autocorrelation function. This leads to a convergent Chapman-Enskog expansion in a fluid provided the proper reference frame is taken in the presence of hydrodynamic motion.

The elastic photoproduction cross sections for $\rho$ and $\varphi$ mesons from protons have been measured from 30 to 180 GeV. The energy dependences agree well with predictions made by using vector-meson dominance and an additive quark model. The $\rho$ cross section is approximately constant with energy while the $\varphi$ cross section rises from 0.5 to 0.7 μb with increasing energy.

With use of the (hitherto obscure) negative-parity meson matrix $N_{+}$ of partial symmetry, an ${\eta }^{\prime }\to \eta \pi \pi$ amplitude, explicitly satisfying the Adler conditions, has been constructed within the relativistic quark pair-creation model without any adjustable parameters. The model yields a total ${\eta }^{\prime }$ width of 388 keV and $\eta \pi \pi$, ${\rho }^0\gamma$, and $\gamma \gamma$ branching ratios of 68.0%, 29.9%, and 1.88%, all in excellent agreement with data. The same model gives the $\pi -\pi$ scattering lengths as $m_{\pi }{a}_0=0.19\mathrm{}$, $m_{\pi }{a}_2=0.08\mathrm{}$.

We consider a superposition of string configurations as a meson trial wave function in quantum chromodynamics and regard its amplitude as a variational parameter. By minimizing the meson energy we obtain a Schrödinger equation and an effective Hamiltonian for the amplitude.

Nonleading quantum chromodynamic corrections to $e^{+}{e}^{-}$ annihilation into hadrons are computed. Comparison with experiment is briefly discussed.

Muon capture in nuclei produced by prompt neutron emission and fission induced by radiationless transitions in the atomic cascade of muons bound to ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$, ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$ is reported. Lifetimes of muons bound to the targets, the ($A-1\mathrm{}$) nuclei, and the neutronrich fission fragments were measured. The lifetimes of the fission-fragment muonic atoms are consistent with the muon of the fissioning muonic atom going predominantly to the heavy-fragment atom.

The first measurements are reported for (${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$) two-proton pickup reactions. Angular distributions for transitions up to ∼3.5 MeV excitation in ${}_{}{}^{44,46}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{48,50}{}_{}{}^{}\mathrm{Ti}$ were obtained with a 51-MeV ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ beam. The angular distributions exhibit a characteristic $l$ dependence. Significant two-proton-hole configurations are found in the first excited $0^{+}$ states of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$(1.88 MeV) and ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$(2.42 MeV). Evidence is presented for multistep excitation of the first $2^{+}$ states, especially in ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ where one-step transitions are expected to be inhibited.

It is suggested that odd-$A$ nuclei be treated as a system of interacting bosons and fermions. It is shown that a simple choice for the form of the boson-fermion interaction is sufficient to describe the variety of observed spectra.

The results of a systematic study of 0° pion production by heavy ions from 125 to 400 MeV/nucleon are presented. The dependence of the cross section on the mass number of the target, the energy of the beam, and the pion charge and energy are discussed. A striking feature of the data is an unexpectedly large $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratio for pions of valocity close to the projectile velocity.

A new method, which has been developed to isolate energy-correlated cascades from a background of uncorrelated events in the $\gamma$-ray continuum, has been applied to the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ +${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ reaction at $E\left({}_{}{}^{16}{}_{}{}^{}\mathrm{O}\right)=80\mathrm{}$ MeV. In ${}_{}{}^{74}{}_{}{}^{}\mathrm{Se}$, the dominant reaction product, it gives $\frac{2\mathcal{I}}{{\hslash }^2}\simeq 53\pm 5 \mathrm{and} 65\pm 6$ ${\mathrm{MeV}}^{-1\mathrm{}}$, respectively, for the rotationallike cascades below and above a phase transition observed at $I\approx 22$ units. These data also indicate that only a small portion of the decay proceeds through rotationallike cascades.

Asymptotic formulas are derived for the high-order perturbation coefficients for the hydrogen Zeeman Hamiltonian. The calculation of 100 coefficients in the series for the ground state are also reported. The method of calculation is based on tilting the Hamiltonian by a generator of SO(2, 1) and the algebraization of the problem by means of the dynamical group SO(4,2).

Using a technique based on the Doppler shift, we have measured the dependence of rate constants for ${\mathrm{Na}}_2$*-Xe rotation-changing collisions on the relative velocity. For ${\mathrm{Na}}_2$* in the $A{{}_{}{}^1{}_{}{}^{}\Sigma _u^{}{}_{}{}^{}}^{+}$ electronic state, we made measurements for four different values of the change in ${\mathrm{Na}}_2$* angular momentum, $\Delta =j_f-j_0$, for each of three initial $j_0$'s. Cross sections for $j_0=66\mathrm{}$ increase with velocity whereas those for $j_0=38\mathrm{} \mathrm{and} 16$ stay constant or decrease. A dramatic decrease is observed for $j_0=16\mathrm{}$ and large $\left|\Delta \right|$.

Recent scattering data are employed to study the interaction $V\left(\overrightarrow{\mathrm{r}}\right)$ between a He atom and a graphite surface. Assuming $V\left(\overrightarrow{\mathrm{r}}\right)$ can be written as a sum of He-C interactions $U(\overrightarrow{\mathrm{r}}-{\overrightarrow{\mathrm{R}}}_i)$, it is found that none of a variety of central potentials $U\left(\right|\mathrm{}\overrightarrow{\mathrm{r}}-{\overrightarrow{\mathrm{R}}}_i\mathrm{}\left|\right)\mathrm{}$ considered is consistent with the data. In contrast, an anisotropic pair potential agrees with scattering and thermodynamic data, and with estimates derived from the electronic properties of graphite.

This Letter presents x-ray studies of freely suspended smectic liquid-crystal films from 2 to >100 layers thick. Smectic-$B$ thick films of butyloxybenzylidene octylaniline (40.8) have three-dimensional long-range order while thin films are two-dimensional crystals. Large diffuse scattering is observed from soft shear waves, propagating perpendicular to the layers, and three new low-temperature phases with different interlayer order in thick films are found.