It is shown that the ratio between the amplitudes of the reactions ${\overline{K}}_0+p\to \Lambda +{\pi }^{+}$ and ${\overline{K}}_0+p\to {\Sigma }^0+{\pi }^{+}$ in the $s$-wave region can be calculated by the quark model under the assumption that no nearby $J={\frac{1}{2}}^{-}$ resonance exists affecting these amplitudes. The parameter ${\mathcal{E}}_{\left(s\mathrm{wave}\right)}$ is shown to be 0.67 and is larger than this if, in addition, $p$ waves are included. The experimental value is 0.35±0.03.

We suggest that the pulses traveling back and forth in a mode-locked laser oscillator are 180° pulses and show that experimental measurements of the width of the pulse in a self-locked He-Ne laser as a function of intensity agree well with the calculated 180° pulse widths for the medium.

Measurements on a number of very pure gold-silver alloys have shown a small specific-heat contribution proportional to $T^{-2\mathrm{}}$, presumably a nuclear specific-heat term.

We have investigated spin-lattice interactions in uranium-doped calcium fluoride at 4.2°K using the method of ultrasonic paramagnetic resonance. We present results of the measurement of the attenuation of 9-GHz longitudinal elastic waves due to the absorption of two phonons by each paramagnetic ion as a function of ultrasonic intensity and angle between the applied magnetic field and the ion symmetry axis, as well as observation of one-, three-, four-, and five-phonon absorption processes.

We present evidence that a change in surface currents from critical paramagnetic to critical diamagnetic (or vice versa) is induced by a suitable increase (or decrease) of the temperature of a semireversible type-II superconductor immersed in a static magnetic field $H<\mathrm{}{H}_{c2\mathrm{}}$.

New techniques for observing the Seraphin effect are presented, which offer additional symmetry information on optical interband thresholds, and eliminate photon-energy restrictions inherent in previous techniques. Examples on GaAs and ZnSe are shown.

We discuss use of electron-magnon scattering as a probe of the magnon spectrum and as a means of producing polarized electron beams.

The Fermi velocity has been measured by a heat-pulse time-of-flight technique near the $a$ axis in gallium. Also, the electron mean free path has been measured in several gallium samples between ∼1.8 and 4.0°K.

The atomic vibrations in a single crystal of Cu-3 at.% Au have been studied using inelastic neutron scattering. The line shapes and widths of the neutron groups, and the shifts from the corresponding frequencies for the host (pure copper), agree substantially with calculations based on the theory of Elliott and Maradudin, but appear to show slight deviations which are in the same direction as, but much less marked than, those exhibited by the results of previous measurements on single crystals of Cu-9.3 at.% Au.