The differential cross sections for elastic scattering of neutrons from Al, Si, P, S and Zn have been observed by means of the time-of-flight technique in an energy range of 3.5 to 4.8 MeV and over angles of scattering from 15° to 160°. The differential cross sections for even-Z element, Si, S and Zn, were compared with those calculated on the basis of an optical potential which was similar to the Bjorklund and Fernbach potential, the depth of the potential being 50 MeV for the real part and 9 MeV for the imaginary part. In the calculation the compound-elastic scattering was calculated by using the penetrability which was computed with the same potential, and this was added to the shape-elastic scattering.
Agreement is fairly good for Si and S except for the case of the lowest energy in the energy range of the present experiment. For Zn the calculated values at the second maximum of the differential cross sections are about two times as high as those observed.

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Four emissions intrinsic to ruby crystals were studied. Two of them were R₁, and R₂ lines. One of the other two emissions located at 14,980 cm⁻¹ was ascribed to the transition from the ²F₁ state. Another broad emission located at about 16,100 cm⁻¹ was tentatively assigned to the emission corresponding to the U absorption band.
The temperature dependences of the relative intensities of these emissions were measured. Thereby, the population in the emitting states was found to be in apparent thermal equilibrium. A comparison of the quantum yield of these emissions excited by the light in the U band with that by the light in the R lines revealed that a competing process exists against the transition from the ⁴F₂ to the ²E state.
The mechanisms of the excitation of the emissions were analyzed. It was concluded that the three processes, i. e. the transition from an optically excited state to the emitting states, the achievement of the thermal equilibrium of populations in the emitting states, and thermal quenchings of the emissions, are all caused by non-radiative transitions through the ⁴F₂ state.
As a result of the analysis some of the frequency factors for these transitions were determined, which agree fairly well with the results of calculations based on the presently known theories. It was pointed out that the frequency factor for the “spin forbidden” transition is smaller by two orders of magnitudes than that for the non-radiative transition between the states of equal spin multiplicities.

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Electromagnetic wave propagation along the axis of a metallic-plated n(or p)-type cylindrical semiconductor in a longitudinal magnetic field is investigated theoretically. Two modes of propagation are found. Both are TE-type waves; one is a surface wave, while the other propagates with a phase velocity which depends on its polarization.

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Measurements have been made of spin-lattice relaxation times T₁ of single Cr ion impurities in ruby and alum, using the decay method at liquid helium temperature. In ruby, T₁ is dependent on the Cr ion concentration C, for specimens having more than 0.01% Cr, whereas in alum T₁ is nearly independent of C. The difference between them is explained in terms of spin-lattice relaxation via exchange pairs. The relaxation time T₁ in ruby varies as C⁻¹ between 0.044% and 0.28%, which agrees with the theoretical prediction. At higher concentrations, T₁ decreases more rapidly with C and its temperature dependence becomes faster than T⁻¹. In very dilute crystals, T₁ at 4.2°K is 200 msec and 3 msec in ruby and alum respectively. The comparison of the values of T₁ for both crystals is given on the basis of the Van Vleck mechanism, and it is shown that the orbit-lattice interaction between Cr and ligand ions is larger in ruby than in alum.

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The reflectivity of neutrons by a single crystal with mosaic structure has been calculated by Bacon and Lowde considering the effect of the secondary extinction. In the present paper, their theory has been modified so as to take the effect of neutron beam collimation into account. The calculated result that the reflectivity should decrease with increasing collimation is experimentally verified for lead and lithium fluoride as monochromating crystals. Furthermore, the results indicate that the mosaic spread should be suitably chosen to obtain the highest reflectivity for each collimation system.

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The effects of the inelastic scattering on X-ray diffraction by a single crystal are theoretically studied. A fundamental dispersion equation for the microscopic electromagnetic fields is quantum mechanically given. By the use of Van Hove’s scattering function the temperature dependence of the absorption coefficient is calculated in the case of the photo-electric absorption of X-rays. The temperature dependence calculated in this way is just e^−M (in usual notation) if the higher phonon excitation is neglected.

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Selected area electron diffraction patterns of an Al-20%Ag alloy including γ′ or γ precipitates have been examined at several angles of incidence and it has been concluded that the appearance of {00.1} spots from the precipitates results from dynamical multiple reflection. The result for the γ′ precipitates is in contrast with previous reports in which these spots were considered to be superlattice spots (e. g., Nicholson and Nutting, 1961).
In this brief report, it is emphasized that the attentions should be paid for dynamical interaction in interpreting electron diffraction patterns.

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By using the double resonance method, transitions F=5→F=4 and F=3→F=2 are measured for 7 ²P_3⁄2 and 8 ²P_3⁄2 states of Cs¹³³ atom (I=7⁄2). Frequency shifts proportional to the input power are observed. In order to compare with the experiment, the theory of frequency shift due to radiation is generalized to the case of transitions between degenerate levels. The result of the calculation is in good agreement with the experimental data.

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The viscoelastic behavior of concentrated polymer solutions is studied by using the network model composed of the Rouse models which have the viscoelastic interactions with medium in contrast with the case of usual network model. The medium is considered to behave as a viscoelastic medium in the phenomena having long relaxation times in which the effect of entanglement participates in the molecular motion. On the other hand, the medium is regarded as a simple viscous medium in the case of shorter relaxation times, as is done in usual treatment for the Rouse model.
The relaxation spectrum covering the both relaxation time ranges is predicted from the unified rheology equation. It is of the wedge type with a slope −1⁄2 for the shorter relaxation times than the critical value, while for the longer ones of the box type.
The viscosity is proportional to the molecular weight when lower than the critical value, and is proportional to the 3.5th power of molecular weight for sufficiently high molecular weights.

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It is reported that the wavelength of moving striations is experimentally proportional to Rⁿ, where R is the tube radius and index n ranges from 1.5 to 2.0. Those measurements are done using tapered discharge tubes. A theory that can give a general explanation of the moving striations is introduced. The relation between the wavelength and the tube radius obtained from those theoretical considerations is in a good agreement with the experimental results.

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In this paper, the effect of a transverse magnetic field on the steady flow of an incompressible electrically conducting elastico-viscous fluid past an infinite porous flat plate has been discussed. Exact solutions have been obtained for the modified Navier-Stokes and Maxwell equations under the usual assumptions of magneto-hydrodynamics. It is found that a steady solution for the velocity field is possible if and only if the magnetic pressure number and elastic number are smaller than unity and there is fluid suction at the plate. The skin-friction at the plate is affected neither by the magnetic field nor by the elasticity of the fluid.
The boundary layer thickness increases due to the presence of the magnetic field, but on the other hand, the elasticity of the liquid decreases it. It has been also found that no steady solution can be obtained for the case of fluid injection at the plate. Several graphs have been drawn to show the effect of magnetic field and elasticity of the fluid on the velocity field, induced magnetic field and the electric current density.

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Heat transfer in stagnation-point flow of an electrically conducting viscous fluid in the presence of a transverse magnetic field and temperature-dependent sources or sinks, has been studied. Composite series for the heat generation or removal parameter β have been constructed with the help of asymptotic-fit method of Rosenzweig. Ratio of heat transfer with and without magnetic field has been calculated by using Bush’s data and also the assumption of Neuringer and Mcllroy for the inviscid flow. It is found that the presence of magnetic field decreases the heat transfer.

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The effective g-value, g′_\varparallel, in Eqs. (14) and (15) should be replaced by g_\varparallel. Then, the value of A_Cd in terms of cm⁻¹ is reduced by a factor of g_\varparallel⁄g′_\varparallel. As g_\varparallel cannot be determined from the present experiment, A_Cd cannot be written in terms of cm⁻¹. However, assuming g_\varparallel=2, A_Cd is given by 5.4×10⁻¹ cm⁻¹, which may be within ±10% of the true value according to the consideration given in Sec. 5 of this paper. The author wishes to thank Dr. T. L. Estle of Texas Instrument for calling his attention to this error.

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On the 3rd line from the bottom on page 1680, the next sentence should be added after “……Bohr magneton respectively.”: θ_i is the angle between the line F¹⁹—nearestneighbour Co²⁺ ions and H₀.

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In Table III, the numerical data in the sixth column and the ones in the seventh column should be interchanged.

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The formula (16) should be replaced by the following formula:
D=\fracμ²C_ET\left[2F₀⁽¹⁾−4\left(F₁⁽²⁾−\fracF₀⁽²⁾F₁⁽¹⁾F₀⁽¹⁾\ ight)+F₂⁽³⁾−\frac2F₁⁽¹⁾F₁⁽³⁾+F₀⁽²⁾F₂⁽²⁾F₀⁽¹⁾+\frac2F₀⁽²⁾F₁⁽¹⁾F₁⁽²⁾+F₀⁽³⁾(F₂⁽¹⁾)²(F₀⁽¹⁾)²−\frac(F₀⁽²⁾F₁⁽¹⁾)²(F₀⁽¹⁾)³\ ight].

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