Showing papers by "University of Tokyo published in 1972"
TL;DR: Water photolysis is investigated by exploiting the fact that water is transparent to visible light and cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm.
Abstract: ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).
27,819 citations
TL;DR: In this article, the intrinsic equation governing the curvature K and the torsion τ of an isolated very thin vortex filament without stretching in an incompressible inviscid fluid is reduced to a non-linear Schrodinger equation.
Abstract: The intrinsic equation governing the curvature K and the torsion τ of an isolated very thin vortex filament without stretching in an incompressible inviscid fluid is reduced to a non-linear Schrodinger equation
\[
\frac{{\rm l}}{i}\frac{\partial \psi}{\partial t} = \frac{\partial^2\psi}{\partial s^2}+{\textstyle\frac{1}{2}}(|\psi|^2+A)\psi,
\]
where t is the time, s the length measured along the filament, ψ is the complex variable
\[
\psi = \kappa\exp\left(i\int_0^{s}\tau \,ds\right)
\]
and is a function oft. It is found that this equation yields a solution describing the propagation of a loop or a hump of helical motion along a line vortex, with a constant velocity 2τ. The relation to the system of intrinsic equations derived by Betchov (1965) is discussed.
968 citations
TL;DR: The performance of the MT technique is discussed from the view point of the output signal-to-noise ratio and the system is shown to attain asymptotically the bound performance predicted by the information theory.
Abstract: A new transmission scheme for channels with intersymbol interference named "matched-transmission (MT) technique" is proposed An implementation of the MT system is presented and its relations with conventional techniques are described It is shown that the partial response scheme is a special case of our new technique The performance of the MT technique is discussed from the view point of the output signal-to-noise ratio and the system is shown to attain asymptotically the bound performance predicted by the information theory
921 citations
TL;DR: In this article, the mechanism of the Aleutian islands earthquake of 1946 and the Sanriku earthquake of 1896 is studied on the basis of the data on seismic waves from 5 to 100 s and on tsunamis.
793 citations
TL;DR: In this paper, the magnetic properties of doped LaMnO 3 were investigated on the basis of an efffective Hamiltonian derived from the s - d model Hamiltonian.
Abstract: Metallic double-exchange ferromagnets such as doped LaMnO 3 are investigatd on the basis of an efffective Hamiltonian derived from the s - d model Hamiltonian. Resistance at low temperatures is calculated in the spin wave approximation and it is found to be proportional to T 9/2 . Magnetic behaviors of the system at finite temperatures are examined by the use of a simple molecular field theory. A magnetization-temperature curve which firs well the experimental data of Leung et al. is obtained. Resistance and magneto-resistance are also studied.
602 citations
TL;DR: To develop this approach toward understanding the operation of cerebellar neuronal machinery, the Vestibulo-cerebellum and its relation with the vestibuloocular reflex arc has been chosen since the neuronal construction of this system is probably the simplest among the Cerebellar-controlled motor systems.
555 citations
TL;DR: In this paper, a nonlinear plane wave solution to this equation is found to correspond to the so-called Stokes wave, and the linear stability of this plane wave is essentially determined by the sign of the product of two coefficients in this equation, yielding Benjamin and Whitham's criterion.
Abstract: Slow modulation of gravity waves on water layer with uniform depth is investigated by using singular perturbation methods. It is found, to the lowest order of perturbation, that the complicated system of equations governing such modulation can be reduced to a simple nonlinear Schrodinger equation. A nonlinear plane wave solution to this equation is found to correspond to the so-called Stokes wave. The linear stability of this plane wave solution is essentially determined by the sign of the product of two coefficients in this equation, yielding Benjamin and Whitham's criterion. The same equation is found to give a weak cnoidal wave derived from the Korteweg-de Vries equation in the shallow-water limit.
510 citations
457 citations
TL;DR: Results support the proposal that ciliary reversal, hence backward swimming, of live paramecia is mediated by an increased cytoplasmic calcium concentration around the ciliary system by calcium-dependent membrane responses to external stimuli.
Abstract: Triton-extracted models of Paramecium were reactivated to swim in solutions of adenosine triphosphate and magnesium ions. The cilia beat in the normal direction (toward the rear) when the calcium ion concentration was less than 10-(6)M, and they beat in the "reversed" direction (toward the front) when calcium ion concentration was raised above 10-(6)M. These results support the proposal that ciliary reversal, hence backward swimming, of live paramecia is mediated by an increased cytoplasmic calcium concentration around the ciliary system by calcium-dependent membrane responses to external stimuli.
433 citations
TL;DR: In this article, the stability of state transition in an autonomous logical net of threshold elements is studied by the use of characteristics of threshold element and the stability degree of their remembering and recalling under noise disturbances is investigated theoretically.
Abstract: Various information-processing capabilities of self-organizing nets of threshold elements are studied. A self-organizing net, learning from patterns or pattern sequences given from outside as stimuli, "remembers" some of them as stable equilibrium states or state-transition sequences of the net. A condition where many patterns and pattern sequences are remembered in a net at the same time is shown. The stability degree of their remembrance and recalling under noise disturbances is investigated theoretically. For this purpose, the stability of state transition in an autonomous logical net of threshold elements is studied by the use of characteristics of threshold elements.
01 Jul 1972
TL;DR: The Associatron is considered to be a simplified model of the neural network and can be constructed as a cellular structure, where each cell is connected to only its neighbor cells and all cells run in parallel.
Abstract: Thinking in the human brain greatly depends upon association mechanisms which can be utilized in machine intelligence. An associative memory device, called " Associatron," is proposed. The Associatron stores entities represented by bit patterns in a distributed manner and recalls the whole of any entity from a part of it. If the part is large, the recalled entity will be accurate; on the other hand, if the part is small, the recalled entity will be rather ambiguous. Any number of entities can be stored, but the accuracy of the recalled entity decreases as the number of entities increases. The Associatron is considered to be a simplified model of the neural network and can be constructed as a cellular structure, where each cell is connected to only its neighbor cells and all cells run in parallel. From its mechanisms some properties are derived that are expected to be utilized for human-like information processing. After these properties have been analyzed, an Associatron which deals with entities composed of less than 180 bits is simulated by a computer. Simple examples of its applications for concept formation and game playing are presented and the thinking process by the sequence of associations is described.
TL;DR: In this article, the thermodynamics of the one-dimensional Heisenberg-Ising model for I.JI < 1 as well as of the X-Y-Z model is reduced to a set of non-linear integral equations under some plausible assumptions.
Abstract: The thermodynamics of the one-dimensional Heisenberg-Ising model for I.JI<1 as well as of the X-Y-Z model is reduced to a set of non-linear integral equations under some plausible assumptions. It is remarkable that the number of unknown functions involved in them becomes finite when rr/cos-1.J is a rational number for the Heisenberg-Ising model and when Kz/t; is a rational number for the X-Y-Z model (where coupling constants J"', Ju and J. are parametrized by f;, l, and J. as J:c=J. en (2t;,l) and Jy=J. dn (2t;,l); 12l20, K!22C20, and K 1 is the complete elliptic integral· of the first kind of modulus l). The validity of our theory has been confirmed by the high-temperature expansion of the free energy through the second term for a general value of .J and through the fourth term for .J=!.
TL;DR: By making genetic mosaics and constructing embryonic “fate maps” it is possible to locate the anatomical site of abnormalities affecting behaviour.
Abstract: By making genetic mosaics and constructing embryonic “fate maps” it is possible to locate the anatomical site of abnormalities affecting behaviour.
TL;DR: In this article, the failure process in rock cutting is observed and the formation of a recompacted crushed zone which sticks to the rake face of the cutting tool and acts as "the built-up edge" in metal cutting is described.
TL;DR: In this article, the authors studied the tectonic process taking place in the south-western part of Japan to the north of the Philippine Sea and found that these two earthquakes represent a low-angle thrust faulting whose slip vector is almost parallel to that of other great earthquakes in the north-western Pacific; the oceanic side is underthrusting beneath the continent.
TL;DR: A mathematical neuron model in the form of a nonlinear difference equation is proposed and its response characteristic is investigated, which explains the “unusual and unsuspected” phenomenon which was found by L. D. Harmon in experimental studies with his transistor neuron models.
Abstract: A mathematical neuron model in the form of a nonlinear difference equation is proposed and its response characteristic is investigated. If a sequence of pulses with a fixed frequency is applied to the neuron model as an input, and the amplitude of the input pulses is progressively decreased, the firing frequency of the neuron model, regarded as the output, also decreases. The relationship between them is quite complicated, but a mathematical investigation reveals that it takes the form of an extended Cantor's function. This result explains the “unusual and unsuspected” phenomenon which was found by L. D. Harmon in experimental studies with his transistor neuron models. Besides this, as an analogue of our mathematical neuron model, a very simple circuit composed of a delay line and a negative resistance element is presented and discussed.
TL;DR: Results appear to indicate that specificity of TRH is not absolute in the functioning pituitary tumor secreting GH in patients with acromegaly or gigantism.
Abstract: Effect of TRH administration on serum TSH and GH was studied in 9 normal subjects and 11 patients with acromegaly or gigantism. TRH provoked a prompt increase of serum TSH in normal subjects, whereas no appreciable change of serum GH was observed. Serum TSH responses to TRH were lower in most of the patients, but 8 out of the patients showed a remarkable increase of serum GH within 30 min after TRH injection. These results appear to indicate that specificity of TRH is not absolute in the functioning pituitary tumor secreting GH.
TL;DR: The histological structure of the lesser and greater curvatures of the stomach was studied in 570 Japanese asymptomatic subjects by means of multiple biopsies taken through a fiberoptic gastroscope, finding the fundic-pyloric border to transit proximally with advancing age and the chronological expansion of atrophic gastritis.
TL;DR: In this paper, the infrared spectra of the solid solution, (Mn, Fe)3O4, were examined and interpreted based on the spectral properties of the end members of the solution.
TL;DR: The polypeptide elongation factors Tu-GDP, Ts and Tu-Ts have been purified from Escherichia coli to homogeneous state as judged by criteria of ultracentrifugation and disc gel electrophoresis.
TL;DR: The method of integral equations with infinitely many unknowns which were used for the one.dimensional Heisenberg model and electron gas is applied to the one-dimensional Hubbard model in this paper.
Abstract: The method of integral equations with infinitely many unknowns which were used for the one.dimensional Heisenberg model and electron gas is applied to the one-dimensional Hubbard model. From these equations one can calculate energy, entropy, density and mag netization at given temperature, chemical potential and magnetic field.
TL;DR: Ritsema et al. as mentioned in this paper presented a phase diagram for the MgSiO3-FeSiO4-SiO2 system at 800 and 1,000°C.
TL;DR: In this article, the temperature dependence of paramagnetic resonance frequencies in a short range ordered spin state is studied theoretically and experimentally for two typical one-dimensional Heisenberg antiferromagnets, CsMnCl 3 2H 2 O and (CH 3 ) 4 NMnCl3.
Abstract: The temperature dependence of paramagnetic resonance frequencies in a short range ordered spin state is studied theoretically and experimentally for two typical one-dimensional Heisenberg antiferromagnets, CsMnCl 3 2H 2 O and (CH 3 ) 4 NMnCl 3 . The present theory with the classical nearest-neighbor Heisenberg model properly predicts the shift of the resonant field from the high temperature limit for both crystals. The observed shift for CsMnCl 3 2H 2 O can be explained only by the dipolar term. For (CH 3 ) 4 NMnCl 3 , however, the effect of the single-ion anisotropy, or the D -term, has to be taken into account in the explanation of the temperature variation.
TL;DR: In this paper, the binding energy of the excitonic molecule, a complex consisting of two electrons and two positive holes, is calculated as a function of the mass ratio m e / m h by avariational method.
Abstract: The binding energy of the excitonic molecule, a complex consisting of two electrons and two positive holes, is calculated as a function of the mass ratio m e / m h by avariational method. It is shown that the excitonic molecule is stable for any value of the mass ratio. For m e = m h , the binding energy is estimated to be 0.00684 \(m_{\text{e}}e^{4}/{\varepsilon_{0}}^{2}\hbar^{2}\). Some results about the wave function are also presented.
TL;DR: It can be concluded that the morphological sex differentiation of germ cells occurs at the time of hatching in Oryzias latipes and no sexual differences in the histological structure of somatic elements in the gonad are observable at that time.
Abstract: Mitotic and meiotic activities of germ cells during early development in the medaka, Oryzias latipes, are dealt with in this report. Primordial germ cells were obviously distinguishable from somatic cells 3 days after fertilization and began to proliferate about 7 days after fertilization. The mean number of primordial germ cells increased during a period of 7–10 days after fertilization, reaching about 90 immediately before hatching. Newly hatched fry could be classified into two types according to the number and the nucleic activity of germ cells in the gonadal rudiment. One type consisted of fry containing about 100 germ cells and no cells in the meiotic prophase. In the other type of fry the number of germ cells increased by mitotic divisions and some of the cells began to enter into the meiotic prophase. During the course of further development the fry of the former type differentiated into males and the latter into females. Therefore it can be concluded that the morphological sex differentiation of germ cells occurs at the time of hatching. However, no sexual differences in the histological structure of somatic elements in the gonad are observable at that time.
TL;DR: In this article, a nonresonant phonon-assisted energy transfer between trivalent rare earth ions is studied using Y 2 O 3 as the host crystal. And the transfer probabilities are obtained from the analysis of the decay rates of donor luminescence for various combinations of donor and acceptor ions in which energy gap, i.e. mismatch of energy, is varied in a wide range up to 4000 cm -1.
Abstract: Nonresonant phonon-assisted energy transfer between trivalent rare earth ions is studied using Y 2 O 3 as the host crystal. The transfer probabilities are obtained from the analysis of the decay rates of donor luminescence for various combinations of donor and acceptor ions in which energy gap, i.e. mismatch of energy, is varied in a wide range up to 4000 cm -1 . The probabilities are decreased exponentially with the increase of energy gap in agreement with the theory of Miyakawa and Dexter. The observed value of the parameter expressing the exponential dependence agrees with the theoretically estimated value. The temperature dependence of the probabilities presents the direct evidence that the mismatch of energy is compensated by the emission of phonons. It is revealed that the phonon of about 400 cm -1 which produces the highest intensity in vibronic sidebands contributes dominantly to the phonon-assisted process.
TL;DR: The mode of action of the Ca ion in regulating the contractile processes of muscle through the troponin-tropomyosin system is briefly described.
Abstract: The Ca ion has many functions in living organisms. In this article, the mode of action of the Ca ion in regulating the contractile processes of muscle through the troponin-tropomyosin system is briefly described.
TL;DR: In this paper, the authors used the modified time-term method for the Kesennuma-Oga profile of the Matsushiro earthquake swarm and determined the distance-dependent velocity.
Abstract: Explosion seismic data in two regions are studied by utilizing the time-term method. The results of two profiles in the Matsushiro earthquake swarm area agree very well with the previous models by ASANO et al. In one profile, the travel-time residuals plotted in the ordinate to distances in the abscissa show a convex tendency which strongly suggests vertical velocity gradient in the basement layer. The distance-dependent velocity is determined accurately with the modified time-term method.Some defects in the model by HASHIZUME et al. for the Kesennuma-Oga profile are removed by the model obtained with the time-term method in the present study. It is particularly remarkable that the possibility of the lateral change in the Pn velocity near the Honshu-Japan Sea boundary is pointed out.