A theory of antennas for gravitational radiation is presented. On the basis of the eigenmode system and the structure symmetry, the emission and reception characteristics and the directivity pattern of antennas are treated. The antenna thermal noise is discussed in connection with the coupling constant of vibration sensors and with the effect of cold-damping.

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This paper is concerned with nucleon radiative capture reactions via giant electric quadrupole (T=0) states in nuclei. The coupling potential between an incident particle and the quadrupole vibrational mode of a target nucleus is described in terms of the hydrodynamic model. A cross section formula for quadrupole capture is derived on the analogy of the collective capture model which has been proposed by Clement et al. Moreover, calculations of the cross section for the ²⁰⁸Pb(n, γ)²⁰⁹Pb reaction with 5- to 20-MeV neutrons are presented for both dipole capture process and quadrupole one. The results show that excitation of the giant quadrupole state by nucleon radiative capture is considerably weak, and so masked by giant dipole resonance (T=1).

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The critical behaviour of the susceptibility of the Ising model with a transverse field is investigated by means of the perturbation expansions. Exact expressions for the coefficients up to seventh order in J⁄kT are given as functions of Δ⁄kT for the quadratic, triangular, simple cubic, b. c. c. and f. c. c. lattices. The universality of the critical index is concluded from the analysis of the coefficients and the critical temperature is obtained as function of the transverse field for the five kinds of lattices.

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The solution of the Bloch equation for many-particle systems on a finite lattice is given in terms of the “path summation”. The boundary conditions we consider are “zero on the boundary” and “the periodic boundary condition”. The obtained expression under the periodic boundary condition is appropriate for the Monte Carlo calculation of the density matrix and the ground state energy of Bose lattice systems and the Heisenberg magnet with a ferromagnetic interaction. For the antiferromagnetic Heisenberg magnet, the present formalism is useful only for the lattices in which each of the closed paths has an even number of edges.

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Statistical theory based on generalized Bethe approximation is developed for the Ising quenched bond model in which ferromagnetic and antiferromagnetic exchange integrals exist. The random ordered phase (ROP) proposed in a previous paper is obtained. The random susceptibility χ_r is calculated, and it is found that χ_r diverges at the critical temperature T_c. It is pointed out that the ordinary susceptibility for the uniform field might have a cusp at T_c.

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Spinodal decomposition process is treated by using the approximation that the probability distribution of concentration is a sum of displaced Gaussians. An emphasis is laid on the interplay of the coherent and incoherent motion. In the early stages, the structure function enhances anomalously due to the growth of incoherent fluctuation. In the late stages, the coherency develops and, through the selection of modes, system is found to approach the equilibrium, phase-separated state.

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The effect of the impurity scattering on the giant quantum attenuation is examined. It is shown that the vertex corrections, which have been neglected so far, are important even in qualitative arguments. The present theory can explain quantitatively the line shape and the frequency dependence of the attenuation observed in experiments of bismuth.

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The superconducting transition temperature T_c and magnetic susceptibility χ in the solid solution Nb_1−xMo_xSe₂ and Nb_1−yTi_ySe₂ were measured T_c and χ in the solid solutions decrease as composition x or y increases. The measured variations of T_c and χ are consistently interpreted by the variation of the Fermi density of states. The electronic density of states curve for these compounds was obtained from the experimental data using the rigid band model. It was found that a sharp peak exists in the density of states centered at the Fermi energy of NbSe₂. This result is in close agreement with the calculation of the band density of states for NbSe₂ by Mattheiss.

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Elastic constants of ReO₃ were determined between −195°C and 30°C by a rectangular parallelepiped resonance technique. It was found that the elasticity of ReO₃ is highly anisotropic. Discussions were made on the Debye temperature, intermolecular force constants, and the effective charges of the ions.

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The magnetic susceptibility and the specific heat of Mn(NH₃)₂·Ni(CN)₄·2C₆H₆ for powder specimen have been measured from 0.3 K to 20 K. The Néel temperature is found at 0.66 K. The Weiss temperature is obtained as −1.52 K with antiferromagnetic coupling. The relation between susceptibility and specific heat which is known as the Fisher’s relation is experimentally verified. The broad maximum of specific heat is observed near 3 K. The origin is not explained as magnetic system through the entropy analysis.

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NMR of F¹⁹ nuclei located on the c-axis in the magnetically ordered K₂CuF₄ and KCuF₃ was studied. A small anisotropic hyperfine field was observed when the electronic moment lies in the c-plane. This field is interpreted as due to the unquenched orbital moment on F⁻ ion which is neglected in usual treatments. The hyperfine interaction arisen from the mixing between dγ and dε orbitals through the spin orbit interaction was considered based on the molecular orbital model. The fractional electron transfer of the 2p_π-bonding was obtained to be 1∼2.5%.

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The magnetic properties of (Fe_1−xCo_x)Si have been studied by means of low temperature specific heat, Co⁵⁹ nuclear magnetic resonance and Mössbauer effect of Fe⁵⁷. An Fe atom substituted for a Co atom in CoSi gives rise to a paramagnetic moment on six nearest neighbor Co atoms. All quantities measured suggest that the magnetic electrons are itinerant. The relationship between the magnetic electron and the transport electron is discussed.

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The magnetizations of the single crystalline binary alloys of Gd with the other heavy rare earth metals, R(=Dy, Ho and Er), were measured at 4.2 K in applied fields up to 54 kOe along the three principal crystallographic directions. The magnetocrystalline anisotropy constants K⁰₂ and K⁰₄ were determined from the analysis of the hard magnetization curves on the basis of the molecular field theory. The anisotropy constants K⁰₂ and K⁰₄ were found to vary quadratically with R concentrations. From these results, it is concluded that the magnetic anisotropy of rare earth metals is attributed to the anisotropic exchange interaction as well as the single ion anisotropy.

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Specific heats of Cr-rich Cr–Fe alloys were measured with an AC-calorimeter. In the range of Fe content less than 1.6 at.%, anomalies due to the transition from paramagnetic to incommensurate spin density wave state (I) are observed together with the stepwise changes for Cr and 0.4 at.% Fe sample. The ordering sequence of paramagnetic-I-commensurate spin density wave state (C) is recognized only on 2.0 at.% Fe sample. The phase boundary of the I–C transition is in a narrow range of Fe content on the low concentration side of the triple point. In the range of Fe content higher than 3.0 at.%, only the P–C transition is observed. The first order P–C transition changes to the second order at a critical point located somewhere around 4.9 at.% Fe.

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The spin wave excitations in the itinerant antiferromagnetics of γFeMn alloys have been studied by neutron scattering. The isotropic dispersion relation has been observed for γFe_0.7Mn_0.3 and γFe_0.5Mn_0.5. The velocities of spin waves at room temperature are 230±30 meVA, 220±30 meVA and 160±30 meVA for Fe_0.7Mn_0.3, Fe_0.5Mn_0.5 and Fe_0.3Mn_0.7, respectively. All samples have the spin wave energy gaps of about 10 meV at 0 K which shows a similar temperature dependence. The damping of the spin wave is significant and it depends on the momentum transfer of the spin waves. The magnon-like excitation persists even 200 degrees above the Néel temperature for Fe_0.5Mn_0.5. The results are favorable to the itinerant electron model where the multiple spin density wave state is assumed to exist.

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Magnetism of Pd with Mn, Fe and Ni impurities is studied by NMR of Al dissolved together as a probe. NMR static properties indicate that Fe and Mn have well localized magnetic moments and are associated with matrix polarization around them, while Ni has no localized moment. Large contribution from localized impurities to Al spin-lattice relaxation is observed in PdMn, but not in PdFe. In PdFe and PdNi relaxation time is not much different from that in Pd. The spin correlation time in these alloys is discussed.

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Electronic densities of states for V–Cr, Nb–Mo and Ta–W alloys are calculated in the coherent potential approximation. From these calculated results, temperature dependences of the electrical resistivity R and the paramagnetic spin susceptibility χ at high temperature are estimated. The calculated results are compared with experiments and a qualitative agreement is obtained. It is shown that the concentration variations of the temperature dependences in R⁄T and χ are strongly dependent on the shape of the density of states near the Fermi level.

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Measurements of magnetic susceptibility (χ_m), in all principal crystallographic directions in a temperature range from 4.2 to 900 K, electrical conductivity (σ) and dielectric constant (ε) parallel to the c-axis from 4.2 to 1180 K, of single crystals of Eu₂(WO₄)₃ are reported. The anisotropy observed in χ_m is assigned to crystal field effect. It is predicted that, this substance may go in magnetic ordered state below 4.2 K. Electrical conductivity σ has been expalined using polaron concept at high temperatures. It has been shown that, below 790 K, intermediate polarons are the entity of the charge carriers which convert themselves slowly into small polarons in a temperature range of 790 to 900 K. Above 900 K, these small polarons conduct by hopping mechanism assisted by optical phonons. Impurity dominates the conduction below 500 K. Mott’s law σ=σ₀(T)exp(−B⁄T^1⁄4) has been shown to be applicable in a temperature range from 180 to 300 K, with B=2.00(K)^1⁄4 and σ₀=6.39×10¹¹ ohm⁻¹ cm⁻¹. Dielectric constant (ε₀) increases at a slow rate from 4.2 to 500 K. The faster increase in ε₀ above 500 K and discrepancy in the temperature range 790 to 900 K, are assigned to thermally generated polarons and intermediate polaron conversion into small polaron respectively.

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Lifetime of magnon arising from magnon-magnon interaction is studied for the general helical spin system by spin wave approach using diagrammatic techniques. The antiferromagnetic MnO, whose spin structure can simply be described as a helix with a wave vector Q=[111]π⁄a, is taken up, and the energies and lifetimes of magnons with wave vectors along [100], [111] and [110] are calculated as functions of temperature. The temperature-dependent line shape of the magnon sideband in MnO corresponding to the transition ⁶A_1g−⁴T_1g of the Mn²⁺ ions is studied with the inclusion of magnon lifetime. The calculated results are compared with the observation.

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The superconducting transition temperature T_c of films of aluminium fine particles deposited by gas evaporation method was determined by measuring dc electrical resistance. The observed values of T_c were distributed from 1.5 to 2.5 K, about 5⁄4∼2 times of that of bulk metal, for the samples of average particle diameter 150∼50 A. The observed enhancement of T_c was not explained by the surface softening of the particles only.

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The phonon dispersion of nickel is reported following a model pseudopotential approach. The potential contains only one unknown parameter which has been adjusted to fit the observed zone boundary frequency of the transverse mode in the [100] direction. The authors’ calculated dispersion curves are in good agreement with the experimental ones.

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The electronic state of hcp titanium-oxygen interstitial alloys is discussed on the basis of measurements of X-ray photoemission spectrum, electrical resistivity and magnetic susceptibility. The Ti 2p and 3p levels shift towards higher binding energy with increasing oxygen content. Considerable anisotropic variations of the resistivity are observed along the directions normal and parallel to the c axis as functions of temperature and composition. It is suggested that the density of states N(E_F) is lower in the ordered state than in the disordered state, and decreases with increasing oxygen content. The additional electrons associated with the oxygens fill probably an oxygen-metal bonding state below the 3d band.

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X-ray, magnetic, electrical and Mössbauer studies are made on Fe_xCo_1−xRh₂S₄ (0≤x≤1.0). These compounds are found to be antiferromagnetic and semiconducting. For x≤0.75, the Mössbauer spectra resemble to each other and show apparently superpositions of many spectra with different values of hyperfine fields and quadrupole splittings. On the assumptions that local tetragonal distoritions occur at all ferrous ion sites in the crystal and that a complex spin structure is formed independently of the distortions, fitting calculations for the observed spectra are made. For x=1.0, the observed spectra are complicated and can not be explained applying such a simplified model only.

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The hole centers produced in MgF₂ crystals irradiated with γ-rays and neutrons at low temperatures have been studied by electron spin resonance. Two kinds of centers were observed in neutron-irradiated crystal and designated as H_N and V_N, respectively. The H_N center has been already assigned to be an interstitial F atom which forms an asymmetric (F^−0.4–F^−0.6) molecular ion with a lattice F ion, while the V_N center is nearly [011]-oriented F₂⁻ molecular ion; a hole trapped by the ions interacts equivalently with each F nucleus. The H_N and V_N centers decay at about 560 K and 185 K, respectively. In γ-rayed crystal a hole center like the V_N canter was produced and named as V_γ center. The V_γ center is also F₂⁻ molecular ion whose bond-axis tilts by several degrees from that of the V_N center. This center decays at around 145 K.

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The g_⁄⁄-values of the excited Kramers doublets, spectral shifts by uniaxial stress and the optical anisotropies of all the absorption-lines in the spectra corresponding to the transition ⁴A₂→²T₂(²D) in Cs₃CoBr₅ and Cs₃CoCl₅ are investigated. The procedure of the assignment of the vibronic spectra is shown for the case that the electronic state is nearly degenerate and the vibronic interaction is weak enough to be treated by the perturbation method. The discrepancy in the assignment of vibronic lines in ⁴A₂→²T₂(²D) of Cs₃CoBr₅ between our result and Quested et al’s is shown to be due to the fact that the optical anisotropy and the MCD pattern do not reflect the symmetry of the electronic state but do that of the vibronic state. It is made clear from the optical anisotropy of vibronic lines that vibronic transitions in ⁴A₂→²T₂(²D) are allowed only by the aid of the even-parity vibronic interaction, while those in ⁴A₂→²E(²D) are allowed not only by the even-parity vibronic interaction, but also by the odd-parity one.

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The emission spectrum is given for radiative decay of the excitonic molecules in the Bose-condensed state at finite temperature which is described in the framework of the Bogoliubov approximation. We take into account the final state interaction of an exciton created in the radiative process with the environment of the Bose-condensed excitonic molecules. The emission spectrum is characterized by a sharp line due to the radiative decay of the Bose-condensed excitonic molecules and the side band at lower energy side due to the process associated with the excitation of the Bose-condensed system. The polariton effect on the emission spectrum is also discussed.

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The valence-band spectrum in X-ray photoemission of PbI₂ does not agree with the reported results of energy-bend calculations, which predict that the highest valence band consists mainly of the 6s state of Pb⁺⁺ and is isolated from other component-bands. Weak lines are found about 6 eV below the valence-band lines in various Pb-compounds. It is suggested that either the weak line in PbI₂ corresponds to the 6s level of Pb⁺⁺ or the upper part of the valence band has both the 6s character of Pb⁺⁺ and the 5p character of I⁻ appreciably. The valence-band spectrum of CdI₂ resembles the valence-band spectrum of PbI₂. The data of the chlorides and bromides of Pb and Cd are also presented.

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Appearance of satellite lines in the X-ray photoelectron emission from the 2p-shell of the metal ion transition-metal compounds are ascribed to the increase of covalency due to the creation of an inner-core hole. For this argument a simple two-configuration model is used, which reveals a shortcoming once ab initio calculations of the line positions and intensities are attempted. The molecular-orbital calculation of multiplet structure of the satellite is performed by taking into account a change of the atomic d-orbital due to the hole in the molecular cluster of (NiF₆)⁴⁻, and a reasonable agreement with experiments is obtained. The reduction of the Coulomb-interaction parameters found in the analysis of the main line can also be explained by our theory. The result shows that the conventional equivalent-core approximation overestimates effects of the hole.

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The phase diagram of the Ca₂Pb_xSr_1−x(C₂H₅CO₂)₆ mixed system is presented on the basis of dielectric and dilatometric anomalies. By the continuity of the phase in the mixed crystal system to those of two end members the space groups of Ca₂Pb(C₂H₅CO₂)₆ are identified to be D₄⁴(D₄⁸) and C₄²(C₄⁴) at high, intermediate and low temperatures, respectively.

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The Pockels effect, linear electro-optic effect, of KDP and ADP is studied in the ultraviolet region near the fundamental absorption edge of the materials. The half-wave retardation voltages of Z-cut crystals are measured, and are found to increase almost linearly with the wavelength in the region longer than 200 nm, but to deviate from the linear relation in the region close to the absorption edge. A new quantity—the electro-optic ρ-coefficient—is defined. The value of ρ₆₃ is different from the value of r₆₃ by a factor of the fourth power of the refractive index for the ordinary rays. The new electro-optic coefficient is more useful than the r-coefficient in discussing the atomic origin of the electro-optic effect, since the dispersion of ρ-coefficient depends only on the change in the dielectric tensor components by applied field, while the r-coefficient depends also on the refractive index.

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Dielectric constants and dielectric losses of pure liquid chloral and ethyltrichloroacetate have been measured in the microwave frequency region upto 60 GHz. For chloral a symmetrical Cole-Cole arc was obtained. The data was analysed in terms of two relaxation times representing overall and intramolecular rotations. For ethyltrichloroacetate a Debye type of behaviour was obtained.

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A peak in the magnetic field derivative of the microwave surface impedance vs magnetic field has been observed in superconducting lead. It is clarified that this peak is associated with the excitation of the surface bound quasiparticles. The temperature dependence of the penetration depth obtained by the analysis of the peak fields has revealed that lead seems to be a weak coupling superconductor having the BCS energy gap 2Δ₀=3.53 kT_c; the gap value differs from the strong coupling value 2Δ₀=4.30 kT_c which was found by the tunneling experiment, although the comparison of the observed penetration depth with the strong coupling theory is not possible at present.

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The Sondheimer oscillations in the electrical resistivity and the Hall coefficient have been measured in copper single crystals. The magnetic field was oriented to the [100] and close to the [110] directions, and it is shown that in these cases the oscillations are interpreted as the type 2 according to the theory of Munarin et al. The field dependence of the oscillation amplitudes have been studied, and a discrepancy with the theory is found. The MacDonald-Sarginson effect has been measured with the magnetic field oriented to the [010] direction. The agreement with the theory of Ditlefsen and Lothe is obtained.

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The fluorescence of Ni²⁺ in RbMnF₃ in the presence of an external magnetic field (parallel to [001]) has been studied and the splitting of the E component of the ³T_2g state as a function of applied external magnetic field has been recorded.
The observed splitting can be explained as due to the second order effect of the exchange field induced by the surrounding Mn²⁺ ions. From the field dependence of the splitting and emission intensities, the exchange field 2μ_BH′_E for the excited state ³T_2g of Ni²⁺ is estimated to be −64.0 cm⁻¹ (antiferromagnetic). This is much smaller than the corresponding value for the ground state (2μ_BH_E=−245.0 cm⁻¹); interpretation is attempted for this reduction of the exchange parameter in the excited state.

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The scattered light around the wavelength of the incident laser and its second harmonic was observed experimentally from the laser produced plasma. The experimental data can be understood consistently by the following model that the second harmonic is produced at the resonance (cut off) region, while the fundamental light is reflected from the turning (before cut-off) region. In the former region, the parametric process produces the large amplitude ion wave, which induces the Brillouin scattering. In the latter region the spectrum broadening of the reflected light is introduced by the self-phase modulation due to the temporal change of the plasma density.

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Calculations for electronic stopping powers has been performed in the cases of protons and alpha particles with energies from 12 keV/amu to 10 MeV/amu in several solid and gaseous target elements. The statistical procedure presented by Lindhard and Scharff and extended by Bonderup and Ashley et al. is refined in the present work in the respect of taking inner shell correction into account. The calculated results are in good agreement with published experimental data above about 200 keV/amu.

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By examining the local eigenvalues of the SSH-equation, it has been clarified that the error caused by disregarding the nonlinear terms in the SSH-equation is not small in case of the relaxation with an appreciable nonresonant V–V energy transfer, e.g., the error amounts to 20% for certain cases.
A solution for the full (nonlinear) SSH-equation has been obtained by using the perturbation method. The error in this solution is within 2% for ε<0.2 during most of the time of relaxation, where ε is a nonresonance parameter defined by ε=1−[1−exp(−θ₁⁄T)]⁄[1−exp(θ₂⁄T)]. Here, T is the translational temperature of the gaseous mixture, and θ₁ and θ₂(>θ₁) are characteristic vibrational temperature of the respective gases.

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The Coulomb-Born approximation is applied to obtain total cross sections of charge transfer reacton between a highly-ionized atom and a proton. The final form of the scattering amplitude is expressed in one dimensional integral to be evaluated numerically. The total cross section is calculated by numerical integration over scattering angles.
Target atoms studied are C, O, Ne, Ar, Fe, Cu, Nb and Mo, because a considerable amount of their ions is found as impurities in fusion plasmas. Very small cross sections less than 10⁻²²∼10⁻²⁴ cm² are obtained for highly-ionized metalic ion-targets (such as Fe, Cu, Nb and Mo). The Coulomb repulsion between the target and the projectile was found to cause a rapid decrease of the cross section as the relative kinetic energy decreases.

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Macroscopic radial motion of a long annular plasma produced by a double theta pinch is studied by experiments and some of the results are compared with calculations using a simple vacuum field model. It is shown that the radial motion is roughly divided into two parts, slow motion of the equilibrium position r₀ and small radial oscillation r₁. The equilibrium position r₀ is controllable by changing the ratio of the current in the ordinary theta-pinch coil to that in the inverse one. The resistance of the plasma has effect to damp both r₀ and r₁ motions, and the damping constant of r₀ is about twice that of r₁. It is also shown that the resistive damping of r₀ can be suppressed selectively by the power crowbarring of the current in the inverse theta-pinch coil, while r₁ damps to vanish by the resistance of the plasma.

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Difference of the collisional effects of the finite-sized particles (clouds) between the single-species plasma and the two-species plasma is studied by invoking the Balescu-Lenard kinetic equation and transforming it to a form near the Landau equation. In order to describe velocity-dependent collisional effects on a test cloud, we express them in terms of a quantity which is reduced to the Coulomb logarithm in the case of the usual point-particle plasma, and compare them with those of the electron cloud plasma. The calculation for the cloud with the radius equal to or larger than the Debye length shows the following properties different from those of the electron cloud plasma: (1) the shielding effect of ion on the fluctuating electric field reduces the collisional effect for the test cloud with the velocity smaller than the ion thermal velocity and (2) the emission of the ion sound wave remarkably increases the collisional effect for the test cloud with the ion sound wave velocity in the moderately nonisothermal plasma.

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An analysis of the anomalous diffusion due to the dissipative trapped ion instability in a toroidal magnetic system is presented. Saturation of the instability is attained both by collisional and by anomalous detrapping of trapped ions. The method of characteristics along the perturbed orbit is used to take into account of the anomalous detrapping effect. The anomalous diffusion coefficient in the saturated state agrees with the result of Kadomtsev and Pogutse.

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There are two factors to control the currents driven by RF fields travelling along a toroidal plasma; one is the penetration depth of the RF magnetic field into the plasma, and the other is the ratio of the RF magnetic field to the static toroidal magnetic field B_t. The currents are observed to increase with B_t, since the skin depth for the RF fields increases. There is optimum toroidal magnetic field to hold a maximum toroidal current, and at higher B_t, the toroidal currents decrease as more strongly than B_t⁻¹. The toroidal current can also be excited by a local assembly of RF coils.

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Contribution of higher order terms in the reductive perturbation theory has been investigated for nonlinear propagation of ion acoustic wave. The basic set of fluid equation is reduced to a coupled set of the Korteweg-de Vries equation for the first order perturbed potential and a linear inhomogeneous equation for the second order perturbed potential. A steady state solution of the coupled set of equations has been examined in details.

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Long wave of small but finite amplitude on an inviscid and incompressible liquid layer with uniform thickness adjacent to a subsonic gas stream is studied in the presence of gravity directed from the gas to the liquid. The gas is an inviscid and ideal gas and is assumed to obey adiabatic law. By taking account of the two-dimensionality of the wave motion, a system of equations governing the finite amplitude waves is derived. It is confirmed that due to the presence of the gas stream an algebraic solitary wave is expected to arise on the liquid layer. The stability of the algebraic solitary wave for the two-dimensional perturbation perturbation is also studied.

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The problem of the onset of convective instability in a horizontal layer of two-component fluid subjected to a vertical temperature gradient is examined taking into account the Soret effect. Applying the linear stability theory and approximations analogous to the usual Boussinesq approximations, an eigenvalue system of eighth order is derived. Making use of the method of power series expansion, this eigenvalue system is solved exactly. The conditions under which the system becomes unstable are determined in detail and the several points of ambiguity in other existing theoretical papers on the same problem are made clear.

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The effect of random bottom inhomogeneities on the propagation of weakly nonlinear surface water waves is investigated by making use of the derivative expansion method combined with the smoothing procedure. In the first-order smoothing approximation, the coherent component of the wave field is shown to be governed either by a generalized nonlinear Schrödinger equation for nonlinear modulated waves or by a generalized Korteweg-de Vries equation for nonlinear long waves. Change in the propagation velocity and damping of amplitude take place due to random inhomogeneities. The damping appears as pseudo-viscosity in the equation for the coherent component of weakly nonlinear waves.

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This paper deals with symmetrical waves of arbitrary amplitude but long wavelength propagating on a thin liquid sheet. These waves are governed by a simple set of two simultaneous equations which allows only periodic wave trains as its steady solutions. From the results obtained in a previous paper, it is highly probable that the steady solutions may be unstable. To conjecture, initial value problems to the set of equations are solved numerically. It is then shown that these waves are remarkably unstable to a subharmonic disturbance. Furthermore, wave energy distributed uniformly at the initial stage is concentrated in a narrow region and at last the solution bursts at a finite time. Thus it is concluded that such a ‘burst instability’ leads to break-up of the liquid sheet.

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The ¹⁴N–¹⁴N PQR spectrum obtained by Brookeman, McEnnan and Scott [Phys. Rev. B 4 (1971) 3661] is interpreted as the superposition of the spectra by both nuclear spin species, o- and p-N₂. The effect of the correlation-corrections to the Hartree approximation for molecular libration on the electric field gradient tensor is studied in the α-phase of p-N₂. The study is based on the electric quadrupole-quadrupole intermolecular potential with molecular quadrupole moment, eQ_m. The predicted value of |eQ_m| agrees with the value obtained from Raman frequencies.

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Time-dependent spin-correlation functions of the two-dimensional finite (3×3=9) isotropic Heisenberg model (spin=1/2) have been calculated at infinite temperatures. The numerical results thus obtained are similar to those of the linear Heisenberg chain.

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Monte Carlo simulations have been carried out on the s. c. lattice consisting of mainly 8×8×8 Ising spins. Random dilutions for both of bond and site problems in the quenched condition have been treated. The transition temperatures obtained are shown to be in good agreement, in the entire region of concentration except near the critical concentration, with those by series expansion in terms of the concentration due to Elliott and Heap.

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