We give a quantum-mechanical treatment for the eigenstates of electrons near saddle points of the energy bands in the presence of a constant magnetic field. We find that Landau-type levels exist depending on the orientation of the magnetic field. Correspondingly, we find peaks in the interband transition probabilities and discuss selection rules on the Landau quantum numbers. We show the behavior of the optical constants for a chosen direction of the magnetic field, and indicate experimental consequences.

Mössbauer measurements have been made on ${\mathrm{Fe}}^{57}$ in iron near the Curie temperature. The discontinuity in the isomer shift near $T_c$ is found to take place within a temperature range of less than 0.3°C, which suggests that this magnetic transition could be of first order. The "critical index" $\beta$ for the variation with temperature of the spontaneous magnetization in the range $0.98T_c<T<\mathrm{}0.9992\mathrm{}{T}_c$ is found to be definitely greater than $\frac{1}{3}$.

The upper-critical-field behavior of type-II superconductors in the presence of strong magnetic exchange fields is reported. In regimes where the exchange fields are temperature dependent the critical-field displays a nonmonotonic dependence on temperature as predicted by de Gennes and Sarma.

A reanalysis of a previously reported experiment on the reaction ${\mathrm{W}}^{182}(d, p){\mathrm{W}}^{183}$ still shows a serious discrepancy in the absolute spectroscopic factors if we use distortion parameters that fit the elastic-scattering data. Similar deviations exist for ($d, p$) reactions on other rare-earth and actinide nuclei.

A superconvergent sum rule for nucleon Compton scattering is derived. The agreement with experiment is good.

Experiments with 6943-Å light scattered from a high-density carbon plasma have resulted in the spectroscopic observation of ion wings produced by plasma ion oscillations. For an energy density of 200 J/${\mathrm{cm}}^2$ and a pulse half-width of 90 nsec, the maximum separation of the ion wings was found to be 0.9 Å. This corresponds to a plasma electron temperature of more than 25 eV and a density of ${10}^{19}$ electrons/${\mathrm{cm}}^3$.

We report a new type of oscillation arising from the coherent motion of large numbers of flux quanta across small-area superconducting contacts. It produces a unique spectrum at the frequency ${\omega }_D$ when $2\pi n{V}_0=N{\Phi }_0{\omega }_D$, where $V_0$ is the dc voltage across the contact, $n$ is an integer, ${\Phi }_0=\frac{h}{2e}$, and $N$ is the number of flux quanta crossing per cycle. The power dependence varies as $N^2$ with values of $N$ from 1 to 200 observed.

Thermal modulation experiments in the low-energy region favor a reordering of the bands at the $L$ point in the Brillouin zone in nickel.

It is pointed out that the classical two-dimensional harmonic "solid" exhibits an infinite generalized susceptibility at low temperature, although there is no long-range order and no phase transition.