Showing papers by "Nagoya University published in 1977"

A classification of irreducible prehomogeneous vector spaces and their relative invariants

Abstract: Let G be a connected linear algebraic group, and p a rational representation of G on a finite-dimensional vector space V , all defined over the complex number field C . We call such a triplet ( G, p, V ) a prehomogeneous vector space if V has a Zariski-dense G -orbit. The main purpose of this paper is to classify all prehomogeneous vector spaces when p is irreducible, and to investigate their relative invariants and the regularity.

Electron-Acoustic Mode in a Plasma of Two-Temperature Electrons

Abstract: It is shown that if electrons of a plasma have two different temperatures, there exists an electron acoustic mode. When the number of high-temperature electrons is smaller than that of low-temperat...

Unsteady flows in a semi-infinite contracting or expanding pipe

Abstract: Physiological pumps produce flows by alternate contraction and expansion of the vessel. When muscles start to squeeze its wall the valve at the upstream end is closed and that at the downstream end is opened, and the fluid is pumped out in the downstream direction. These systems can be modelled by a semi-infinite pipe with one end closed by a compliant membrane which prevents only axial motion of the fluid, leaving radial motion completely unrestricted. In the present paper an exact similar solution of the Navier–Stokes equation for unsteady flow is a semi-infinite contracting or expanding circular pipe is calculated and reveals the following characteristics of this type of flow. In a contracting pipe the effects of viscosity are limited to a thin boundary layer attached to the wall, which becomes thinner for higher Reynolds numbers. In an expanding pipe the flow adjacent to the wall is highly retarded and eventually reverses at Reynolds numbers above a critical value. The pressure gradient along the axis of pipe is favourable for a contracting wall, while it is adverse for an expanding wall in most cases. These solutions are valid down to the state of a completely collapsed pipe, since the nonlinearity is retained in full. The results of the present theory may be applied to the unsteady flow produced by a certain class of forced contractions and expansions of a valved vein or a thin bronchial tube.

Temperature variation of elastic constants of single-crystal forsterite between -190.DEG. and 400.DEG.C.

Abstract: Elastic constants of forsterite Mg2SiO4 were measured by the rectangular parallelepiped resonance (RPR) method at temperatures between -190° and 400°C. Elastic constant Cij(Mbar) and their temperature derivatives ∂Cij/∂T (kbar/deg) are:The adiabatic bulk modulus Ks=1.292Mbar (25°C) and its temperature derivatives ∂Ks/∂T=-0.160kbar/deg (20°-400°C) are obtained by the Voigt-Reuss-Hill scheme.In the temperature range from 100 to 1000K, the Gruneisen constant calculated from the measured bulk modulus is virtually constant at 1.1±0.1, while the Gruneisen-Anderson parameter δs, defined as -(∂ In Ks/∂T)/α(α: the coefficient of volume thermal expansion), decreases with increase of temperature, but tends to approach a constant value of 4.0±0.1 above 500K.

Breast cancer incidence according to weight and height in two cities of the Netherlands and in Aichi prefecture, Japan

Abstract: A study was made in the cities of Rotterdam and The Hague, the Netherlands, and in Aichi prefecture, Japan, to assess the effect of weight and height (and their combinations) on the age-specific incidence of breast cancer. It is based on a comparison between 1006 cases of breast cancer and 4201 women from the general population, 35–69 years old. The results suggest that about one-half of the differences in incidence between the regions in Holland and Japan can be attributed to differences in body weight and height. In breast cancer patients in Rotterdam and The Hague those with metastases in axillary nodes were significantly heavier but not taller than those without nodal involvement. A hormonal factor related to body weight and/or height might be responsible for the increased incidence and the more rapid course of breast cancer in women with a large body mass.

DC Treeing Breakdown Associated with Space Charge Formation in Polyethylene

Abstract: It is well known that space charge accumulation has a great influence on both the short-time and long-time breakdown strengths of plastic insulation systems operating under direct voltages. In this paper, dc treeing phenomena initiated from the tip of a needle electrode inserted into a polyethylene specimen have been investigated under various conions. The characteristics of four kinds of trees, dc tree, short-circuit tree, polarity reversal tree and impulse tree, were investigated as a function of the voltage-rising speed, period of dc prestress, time before the short-circuit or the application of a voltage of reversed polarity, impulse voltage, needle electrode material and temperature, etc. Also, thermally stimed current (TSC), thermoluminescence (TL) and photo-induced current techniques were applied to estimate the nature of the trapped carriers and carrier trapping centers. From the experimental results, it was concluded that a homo-charge is formed at high electric stresses and that the homo-charge induces an electric field distortion around the needle tip. In order to explain the length of the tree as a function of the various factors mentioned above, a model for the space charge formation is proposed, including the process such as charge injection, trapping and its diffusion.

Progressive ordering of cristobalitic silica in the early stage of diagenesis

Abstract: Examination of hydrothermally transformed silica from controlled experiments reveals that amorphous silica changes to quartz through an intermediate phase of opal-CT and that the d(101) spacing of cristobalite progressively decreases from 4.10 A to 4.05 A. The rate of spacing decrease is definitely dependent on the reaction temperature, being faster at higher temperatures. This spacing change represents ordering of opal-CT crystals with the passage of time. The relationship between thermal history and degree of ordering suggests that stratigraphic boundaries are usually parallel to isopleths of d (101) spacings, but do not always coincide with them. The isopleths should be more or less discordant to the stratigraphic boundaries where the strata have been folded. This discordancy can be ascribed to the difference of ordering, chiefly controlled by the thermal history during the burial and folding process.

Attractancy of Optically Active Pheromone for Male Gypsy Moths

Abstract: Synthetic attractant lures enriched in the (+) enantiomer of cis -7,8-epoxy-2-methyloctadecane were many times more effective in eliciting trap catch of male gypsy moth, Lymantria dispar (L.), than racemic cis -7,8-epoxy-2-methyloctadecane. The lowered trap catch at the racemate was due to the antagonistic effects of the (−) enantiomer on the male behaviors of long-range upwind flight, the likelihood of landing on the baited trap and duration of the persistent “searching” behavior of wing fanning concurrent with walking on the trap. The admixture of 2-methyl-( Z )-7-octadecene with the (+) enantiomer also effected a reduction in trap catch.

The Effects of Impurities on Superconductors with Kondo Effect

Abstract: The Green's functions of s- and d-electrons in superconductors are obtained on the basis of the interpolation theory'>,'> which includes as impurity effects the pair breaking and the effective repulsive interaction between s-electrons. By the use of these Green's functions, the order parameter and the critical magnetic field at zero temperature in the presence of impurities and its initial decrease are given. The localized excited state in the gap 1s found and shown to be doublet, differently from that of MUller-Hartmann and Zittartz.

The Lower Frequency Soft-Mode in the Ferroelectric Phase of K2SeO4

Abstract: In the ferroelectric phase below T 3 (93 K) of K 2 SeO 4 a new soft-mode, belonging to the B 2 representation, has been observed by means of Raman scattering experiment. This mode is different from the soft A 1 mode previously reported to soften as T 2 (129.5 K) was approached from below. The frequency of this newly observed mode is abotut 13.2 cm -1 at 9.8 K, and decreases as the temperature increases. The observed result is discussed in connection with the successive phase transitions in the K 2 SeO 4 crystal.

Ionic Conductivity of Doped Cerium Trifluoride

Abstract: The electrical conductivities of the tysonite‐type fluorides based on in the sintered state were measured for various aliovalent cation dopants. Doping of difluoride such as , , or up to 5 mole percent made the conductivity increase while the doping of tetrafluoride such as led it to decrease. These facts together with the experimental results of electrolysis indicated that the specimens were fluoride ion conductors resulting from the easy movement of fluoride ion vacancies. The activation energies for conduction at the high temperature range above 250°C were, in general, about 0.25 eV irrespective of divalent dopant species, while those at lower temperatures were depending on the dopant species. Their conductivities are, in general, higher than those of the electrolytes which are also the tysonite‐type fluorides. had the highest conductivity among the tysonite‐type fluorides ever examined.

Raman Scattering Spectra of K2SeO4

Abstract: The Raman spectra in potassium selenate single crystal were measured over the temperature range 77∼300 K. The spectra contain components due to internal vibrations of selenate radicals in the frequency region 300∼900 cm -1 , and those due to external lattice vibrations in the region 0∼200 cm -1 . The soft-mode was observed whose frequency decreases as the transition point T 1 (129.5 K) is approached from below. On the basis of these results the relationship between the soft-mode and the phase transition is discussed.

2-Deoxy-alpha-ecdysone from ovaries and eggs of the silkworm, Bombyx mori.

Abstract: From ovaries dissected from developing and emerged adults of the silkworm, Bombyx mori, two substances having high molting hormone activity were isolated. One of these was identified as 2-deoxy-alpha-ecdysone by means of high-pressure liquid chromatography and mass spectrometry. Although this compound had previously been isolated from the fern Blechnum minus and postulated to be the precursor of alpha-ecdysone, it had not been obtained from insect material. The compound is also contained in the form of a conjugate in ovaries as well as in diapausing silkworm embryos.

Upper mantle P structure on the ocean side of the Japan‐Kurile Arc

Abstract: Slowness measurements are made for the first and later arrivals of P waves from about seventy Kurile-Kamchatka earthquakes (13° < Δ < 30°) at the Wakayama Micro-Earthquake Observatory, Japan. The experimental error of dT/dd is not more than 3 per cent and the data points suffice to draw a dT/dΔ curve fairly uniquely. In the distance range 4° < Δ < 15° a travel-time curve, including a later arrival branch, is constructed for a specific Kurile event using the records along the Pacific coasts of the Japanese-Kurile islands. The results are inverted to obtain a velocity model for the upper 800 km of the mantle beneath the trench side of the Japan-Kurile Arc. The model includes a high-velocity lid extending down to 85 km depth. The low-velocity zone is of relatively high speed (8.1 km/s) and is terminated by a high-velocity gradient zone at depths 165-200 km, just below which the velocity is nearly constant with depth. The velocity increases very sharply near 400 km by about 6 per cent. An abrupt change in the slope of velocity occurs near 520 km. A major transition zone in the depth range 630-670 km consists of about 7 per cent increase in velocity and is sharp, especially near the base. A minor transition zone is tentatively suggested to exist around 740 km. Relative arrival times, crossover distances and qualitative amplitude behaviour calculated for this model are consistent with the observed data. Station residuals for the least-squares determination of dT/dΔ closely correlate with the local seismicity.

Accurate electronic energies of He ++ 2

Abstract: Accurate adiabatic potential curves are calculated for the ground state and 11 excited states of ${\mathrm{He}}_{2}^{++}$ using the James-Coolidge method. The values are the best of all existing results for this system. The number of basis sets used was 75 for $^{1}\ensuremath{\Sigma}_{g}^{+}$ and 57 for $^{1}\ensuremath{\Sigma}_{u}^{+}$, $^{3}\ensuremath{\Sigma}_{g}^{+}$, and $^{3}\ensuremath{\Sigma}_{u}^{+}$. The ground-state energy curve has both a dip and a peak. A dip is also expected for the lowest $^{1}\ensuremath{\Sigma}_{u}^{+}$ state.

Conduction in Bi2O3-based oxide ion conductors under low oxygen pressure. I. Current blackening of the Bi2O3-Y2O3 electrolyte

Abstract: The cathodic current blackening of Bi2O3-based oxide ion conductors was examined for the Bi2O3-Y2O3 electrolyte at low oxygen pressure. In air, more than 500 mA cm−2 d.c. could be passed at 600° C without causing changes in the electrolyte itself. However, in argon gas, a limiting current of 3 mA cm−2 was observed and the electrolyte was blackened at the cathode side. The limiting current was ascribed to control by the diffusion of oxygen gas at the cathode. The blackened oxide was found to consist of a mixture of Bi metal and Bi2O3-Y2O3 solid solution and to exhibit the equilibrium oxygen partial pressure almost corresponding to that of the Bi, Bi2O3 mixture.