Showing papers by "University of Tokyo published in 1977"
TL;DR: The Protein Data Bank is a computer-based archival file for macromolecular structures that stores in a uniform format atomic co-ordinates and partial bond connectivities, as derived from crystallographic studies.
7,983 citations
TL;DR: The inhibitors of Ca-induced Ca release––procaine and adenine––were shown not to inhibit contraction of living skeletal muscle fibers induced by the depolarization of the surface membrane.
Abstract: Publisher Summary Ca release from the sarcoplasmic reticulum (SR) is one of the most important steps in excitation–contraction coupling of skeletal muscle. This chapter describes the physiological release of Ca from the SR, various modes of Ca release from the SR, and the physiological significance of various Ca release mechanisms. Ca ion is the mediator of information of action potentials to the contractile machinery; however, the physiological source of the mediator Ca is not yet unequivocally established. The inhibitors of Ca-induced Ca release––procaine and adenine––were shown not to inhibit contraction of living skeletal muscle fibers induced by the depolarization of the surface membrane. Studies of the ionic composition of the lumen of the SR by electron-probe analysis show that there are no significant differences between the ionic compositions in the lumen of the SR and that in the cytoplasm except for Ca ion. The essential part of the physiological Ca release mechanism is almost entirely unknown; therefore, further studies, especially by using preparations, such as improved cut fibers, that retain the physiological tubule (T)–SR coupling mechanism, but have easy access to sarcoplasm so that its composition can be altered at will, are necessary.
1,481 citations
TL;DR: A new multilevel coding method that uses several error-correcting codes that makes effective use of soft-decisions to improve the performance of decoding and is superior to other multileVEL coding systems.
Abstract: A new multilevel coding method that uses several error-correcting codes is proposed. The transmission symbols are constructed by combining symbols of codewords of these codes. Usually, these codes are binary error-correcting codes and have different error-correcting capabilities. For various channels, efficient systems can be obtained by choosing these codes appropriately. Encoding and decoding procedures for this method are relatively simple compared with those of other multilevel coding methods. In addition, this method makes effective use of soft-decisions to improve the performance of decoding. The decoding error probability is analyzed for multiphase modulation, and numerical comparisons to other multilevel coding systems are made. When equally complex systems are compared, the new system is superior to other multilevel coding systems.
1,070 citations
TL;DR: The theory is useful for the analysis of fluorescence polarization decay in any system where the orientation of fluorophore is restricted by the surrounding structure.
857 citations
TL;DR: The Protein Data Bank is a computer-based archival file for macromolecular structures that stores in a uniform format atomic co-ordinates and partial bond connectivities, as derived from crystallographic studies.
Abstract: The Protein Data Bank is a computer-based archival file for macromolecular structures. The Bank stores in a uniform format atomic co-ordinates and partial bond connectivities, as derived from crystallographic studies. Text included in each data entry gives pertinent information for the structure at hand (e.g. species from which the molecule has been obtained, resolution of diffraction data, literature citations and specifications of secondary structure). In addition to atomic co-ordinates and connectivities, the Protein Data Bank stores structure factors and phases, although these latter data are not placed in any uniform format. Input of data to the Bank and general maintenance functions are carried out at Brookhaven National Laboratory. All data stored in the Bank are available on magnetic tape for public distribution, from Brookhaven (to laboratories in the Americas), Tokyo (Japan), and Cambridge (Europe and worldwide). A master file is maintained at Brookhaven and duplicate copies are stored in Cambridge and Tokyo. In the future, it is hoped to expand the scope of the Protein Data Bank to make available co-ordinates for standard structural types (e.g. alpha-helix, RNA double-stranded helix) and representative computer programs of utility in the study and interpretation of macromolecular structures.
581 citations
TL;DR: In this article, the instantaneous rotation vector of the Philippine Sea plate relative to the Eurasian plate is determined (pole: 45.5°N, 150.2°E, angular velocity: 1.20 deg/m.y.).
472 citations
TL;DR: An evolutionary history of the western Pacific is presented by reconstructing the spreading systems of the region since Middle Mesozoic time on the basis of marine magnetic lineations, paleomagnetic data, DSDP results, and selected other data as mentioned in this paper.
467 citations
TL;DR: In this paper, the authors described the collective nuclear states by symmetric couplings of proton and neutron pairs, represented by s- and d-bosons respectively, and the multiplet structure of the combined system was given by representations of the SU (6) × SU (2) group, the Arima-Iachello interacting bosons corresponding to the fully symmetric ones.
463 citations
TL;DR: In this article, a human lung cancer (OTUK-tumor) was transplanted serially to nude mice, which invariably developed a marked neutrophilia, and a three to fourfold increase of colony-forming units in culture was observed in the femurs of these nude mice.
436 citations
TL;DR: The decay curves of r(t) indicates that the orientational motion of DPH in the hydrocarbon region is described by a wobbling diffusion restricted by a certain anisotropic potential.
Abstract: Molecular motions in liposomes of dipalmitoyl- phosphatidylcholine (DPPC) were studied by nanosecond fluorescence techniques. As a fluorescent probe for the hy- drocarbon region, 1,6-diphenyl-1,3,5-hexatriene (DPH) was used. Time courses of fluorescence intensity ZT(t) and emission anisotropy r(t) of DPH embedded in DPPC liposomes were measured at various temperatures. The value of the fluores- cence lifetime 7 obtained from a single exponential decay of Ir(t) was somewhat higher than that in liquid paraffin below the transition temperature TI and decreased above TI. Higher values of 7 below TI, indicate the almost complete hydrophobic environment. The decay curves of r(t) were separated into two phases: an initial fast decreasing phase of the order of one nanosecond and a second almost constant phase. This indicates Structure and dynamics of lipids in biological membranes have been recognized as the essential factors in their functions and organization (Inesi et al., 1973; Racker and Hinkle, 1974). Phospholipids in model membranes such as aqueous disper- sions or liposomes are known to be in a bilayer structure and the cooperative melting of their hydrocarbon chains, the crystalline-liquid-crystalline phase transition, takes place at a certain temperature (Trauble and Eibl, 1974; Sackmann et al., 1973; Chapman, 1975; Jacobson and Papahadjopoulos, 1975). Studies of dynamic properties or molecular motion of lipids in model bilayers, however, have not resolved several important questions. Although the use of spin-label techniques for the dynamic studies of lipid bilayers is widespread, the information re- garding molecular motion is restricted in most investigations. In describing the characteristics of molecular motion of that the orientational motion of DPH in the hydrocarbon re- gion is described by a wobbling diffusion restricted by a certain anisotropic potential. The results were analyzed on the model that the wobbling diffusion is confined in a cone with a uniform diffusion constant. Though temperature dependence of the cone angie was sigmoidal, that of the wobbling diffusion con- stant was like the exponential function. The change in the cone angle at TI was sharper than that in the wobbling diffusion constant at TI. Estimated values of the viscosity in the cone were an order of magnitude smaller than the values of "mi- croviscosity" which were estimated from the steady-state emission anisotropy without considering the restrictions on the rotational motion.
425 citations
TL;DR: In this paper, the interrelation between the well-known non-Markovian master equation and the new memoryless one used in the previous paper is clarified on the basis of damping theory, and the latter equation is generalized to include cases in which the Hamiltonian or the Liouvillian is a random function of time.
Abstract: The interrelation between the well-known non-Markovian master equation and the new memoryless one used in the previous paper is clarified on the basis of damping theory. The latter equation is generalized to include cases in which the Hamiltonian or the Liouvillian is a random function of time, and is written in a form feasible for perturbational analysis. Thus, the existing stochastic theory in which those cases mentioned above are discussed is equipped with a more tractable basic equation. Two problems discussed in the previous paper, i.e., the random frequency modulation of a quantal oscillator and the Brownian motion of a spin, are treated from the viewpoint of the stochastic theory without such explicit consideration of external reservoirs as was taken in the previous paper.
TL;DR: In this article, a pyroxene-garnet solid-solution equilibria have been studied in the pressure range 41-200 kbar and over the temperature range 850-1,450°C for the system Mg4SiO3 in pyrope (Mg3Al2Si3O12), and in a pressure range 30-105 kbar, and over a temperature range 1,000 -1,300
TL;DR: In this paper, the effects of grain size distribution on shear moduli of normally consolidated disturbed sands for shear strain ranging from 10-6 to 10-4 were investigated and it was concluded that it is preferable to conduct resonant-column tests on the sands of interest.
TL;DR: In this article, a general phenomenological theory of spin-glasses is presented, which predicts the weak singularities (like cusps) of susceptibilities and specific heat near the transition point TsG and also predicts generally the divergence of the second derivative of the nonlinear susceptibilities with respect to a magnetic field in zero field at Tsa.
Abstract: A general phenomenological theory of spin-glasses is presented, which predicts the weak singularities (like cusps) of susceptibilities and specific heat near the transition point TsG and also predicts generally the divergence of the second derivative of the nonlinear suscepti bility with respect to a magnetic field in zero field at Tsa. A similar second derivative of specific heat is also shown to diverge at Tsa except for the molecular field theory. Scaling equations of state for magnetization m and spin-glass order-parameter q are derived, which yield new scaling relations of critical exponents for m(T), q(T), X,(T), Co(T) and the corresponding nonlinear quantities. These general results explain qualitatively very well the magnetic field dependence of magnetization and specific heat observed experimentally. A non-uniform phenomenological Hamiltonian is also proposed for the rcnormalization group approach, which yields the critical dimensionality d,=6, as usuaL Intermediate random statistics and real replica method are p;oposed. There is also presented an exactly soluble model showing a spin-glass like phase transition.
01 Jan 1977
TL;DR: There is a strong probability that cooked foods in which charred material from proteinous components are produced might play a role in carcinogenesis generally occurring in human, and the correlation between mutagens and carcinogens have been generally accepted in recent investigations.
Abstract: We previously reported that smoke condensates from fish showed high mutagenic activity (Nagao et al., 1977a ; Sugimura et al.,1977) . Charred material in the surface layer of broiled fish and meat also contained a high mutagenic potential (Nagao et al., 1977a; Sugimura et al., 1977). Subsequently it was revealed that mutagenic principles were formed by pyrolysis of protein but not carbohydrate, nucleic acid and vegetable oil (Sugimura et al., 1977). This report deals with mutagenic principles in the pyrolysis products of D, L-tryptophan and D, L-phenylalanine. The most plausible structures from the former were 3-amino-1, 4-dimethyl-5H-pyrido [4, 3-b] indole and 3amino-l-methyl-5H-pyrido [4, 3-b] indole. The structure of the active principle of D, L-phenylalanine was proved to be 2-amino-5-phenylpyridine. Since pyrolysis products are very likely to be produced by cooking proteinous food, such as fish and meat, by direct exposure to the flame, and since the correlation between mutagens and carcinogens have been generally accepted in recent investigations (McCann et al., 1975 ; Sugimura et al., 1976), there is a strong probability that cooked foods in which charred material from proteinous components are produced might play a role in carcinogenesis generally occurring in human. Mutagenicity tests were carried out using an improved method (Nagao et al., 1977b; Yahagi et al., 1977) of the Ames test (Ames et al., 1975). Test material, bacteria and S-9 Mix prepared from the liver of rats treated with polychlorinated biphenyl were prein-
TL;DR: The theory of the electronic excitations in a highly excited semiconductor is presented in this paper, where the relaxation processes, the formation of excitons and excitonic molecules, the interaction among the various forms of electronic excitation, as well as their optical and thermodynamical properties are analyzed.
TL;DR: In this paper, the authors made mention of carbon-carbon linkage with TiCl4 which permits the synthesis of hydroxy ketones and carbonyl compounds of the Michael adduct type.
Abstract: Titanium tetrachloride can accelerate numerous organic reactions. Valuable syntheses of, e.g., allyl sulfides, amides, enamines, and ketones are based upon transformations of functional groups with TiCl4. Particular mention should also be made of carbon-carbon linkage with TiCl4 which permits the synthesis of hydroxy ketones and carbonyl compounds of the Michael adduct type. TiCl4 reduced in situ is suitable for the reduction of chloroarenes or the linkage of two aldehyde molecules to give an alkene.
TL;DR: In this article, the authors examined the probability of polar substorms by a large-scale magnetospheric compression associated with a discontinuity in the solar wind using ground magnetogram data, AE index data and satellite geomagnetic data.
Abstract: The probability of triggering of polar substorms by a large-scale magnetospheric compression associated with a discontinuity in the solar wind has been examined statistically using ground magnetogram data, AE index data and satellite geomagnetic data on 125 sudden storm commencements observed during 1967-1970. The triggering probability was found to depend on the amplitude of the sudden storm commencement and on the degree of preceding AE activity. In almost all cases the triggering occurred when the B-Z component of the interplanetary magnetic field was negative or decreasing during the 30 min before the passage of the discontinuity. Transient geomagnetic responses with a time scale of Alfven wave propagation in the polar cap also depend on interplanetary magnetic field conditions.
TL;DR: A general explicit formulation of Monte Carlo simulation for quantum systems is given in this article on the basis of the previous fundamental proposal by Suzuki, and new interesting physical results on the two-dimensional XY-model are given.
Abstract: A general explicit formulation of Monte Carlo simulation for quantum systems is given in this paper on the basis of the previous fundamental proposal by Suzuki. This paper also demonstrates explicitly the possibility of it and gives new interesting physical results on the two-dimensional XY-model. That is, the present preliminary simulation seems to indicate a phase transition with a divergent susceptibility, and a very weak singularity of specific heat if it exists, and without long-range order.
TL;DR: It was concluded that stones larger than 8 mm. in width on x-ray films should be removed surgically, while in those smaller than 8 millimetre in width higher chances of spontaneous passage by expectant treatment would be anticipated.
TL;DR: In this paper, the broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p-type Si at zero temperature.
Abstract: The broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p -type Si at zero temperature. Main scattering mechanisms are assumed to be charged impurity scattering and surface roughness scattering. A new expression for the surface roughness scattering is obtained. The self-consistent Born approximation is employed for the effect of scattering, and the random phase approximation for the screening. Because of the singular density of states the screening depends on the position of the Fermi level and becomes weak when it lies at the tail region of each Landau level. Scattering potentials become strong and of slowly varying type in this case. Except such a special case, overall features agree with the results obtained for short-ranged scatterers.
TL;DR: Threshold changes of Na and Ca currents due to various polyvalent cations (stabilizing cations) or H+ ions were studied in the egg cell membrane of a tunicate, Halocynthia roretzi, by using the voltage‐clamp technique.
Abstract: 1. Threshold changes of Na and Ca currents due to various polyvalent cations (stabilizing cations) or H(+) ions were studied in the egg cell membrane of a tunicate, Halocynthia roretzi, by using the voltage-clamp technique.2. With an increase in [Ca](o) or a decrease in pH in the external solution, the current-voltage (I-V) relations for the peak of the Na and Ca currents shifted along the voltage axis in the positive direction. These voltage shifts in the I-V relations, measured at a potential of V((1/2)) where inward current attains its half-maximum, were shown to be identical to shifts in voltage-dependence of the time courses of Na and Ca currents, and also identical to shifts in the inactivation curves of Na current along the voltage axis.3. The shifts in V((1/2)) produced by various polyvalent cations or H(+) ions were analysed by the Gouy-Chapman equation for the diffuse double layer, by assuming that a change in V((1/2)) directly corresponds to a change in the surface double layer potential.4. The V((1/2))-divalent cation concentration relations of Na current were exactly described by the predictions of the theory with a constant value of the surface charge density of 1e(-)/(9 A)(2). The weak stabilizing effects of Mg(2+), Sr(2+) and Ba(2+) were quite similar to each other and were explained in terms of a ;screening' effect. Other divalent cations, such as Ca(2+), Mn(2+) and Ni(2+), showed various different stabilizing effects which were explained in terms of a ;binding' effect. The binding constants (K(1)'s) for Ca(2+), Mn(2+) and Ni(2+) were 0.21, 0.45 and 0.94 M(-1), respectively.5. H(+) ions showed a powerful stabilizing effect upon the Na current with a K(H) of 6 x 10(4)M(-1). This value indicates that the acidic sites around Na channels have a pK(a) of 4.78. La(3+) ions also acted as a strong stabilizer upon the Na current with a K(La) of 15 M(-1). For both H(+) and La(3+), the V((1/2))-concentration relations were also exactly described by the Gouy-Chapman equation with the same charge density of 1e(-)/(9 A)(2) as estimated by varying divalent cations.6. The stabilizing effect of permeant cations such as Ca(2+), Sr(2+) and Ba(2+) on Ca channel currents was analysed. The effect of lowering pH was also studied. It was found that the surface charge density of 1e(-)/(9 A)(2) estimated by Na current is also applicable to the explanation for the V((1/2))-divalent cation concentration or - pH relationships. The estimated binding constants for H(+), Ca(2+) and Sr(2+) were 1.2x10(5), 0.58 and 0.035 M(-1), respectively. Ba(2+) does not bind to charged sites near to the Ca channels.7. It was noticed that a considerable reduction in the conductances of Na and Ca currents occurred in parallel with a stabilizing effect. This reduction was ascribed to a decrease in the concentration of permeant cations at the external surface of the cell membrane, as predicted by the theory of the diffuse double layer. The Goldman, Hodgkin-Katz equation for ionic currents was applied to explain the conductance suppression.8. The conductance suppressions of Na and Ca channel currents due to Ca(2+), Sr(2+) and Ba(2+) were found to be apparent ones, only reflecting decreases in the surface concentration of permeant cations without any changes in the permeability. After correction for the apparent suppression, the real permeability ratio among Ca(2+), Sr(2+) and Ba(2+) for Ca channels was determined as 1.00, 0.56 and 0.21 respectively.9. The conductance suppression of Na current by lowering pH was explained in terms of a real suppression or blocking which is superimposed on the apparent suppression. Considering the surface [Na](o), the plot of P(Na) against the surface pH yielded a blocking curve of Na channel by H(+) ions, which implies that two H(+) ions are necessary to block each Na channel. For Ca channels no real blockage was observed in acidic pH.10. It was concluded from the present experiment that there exists a surface potential capable of affecting both gating and permeation mechanisms of ionic channels in this tunicate egg cell membrane.
TL;DR: In this paper, the Weinberg angle is determined to be 3.8 times the fine-structure constant for fractionally charged quarks, which coincides with the prediction of Georgi and Glashow in their unified SU(5) gauge model.
Abstract: The unified model for all elementary-particle forces recently proposed by us is discussed in detail. Starting with a nonlinear fermion Lagrangian of the Nambu-Jona-Lasinio type and imposing the massless conditions of Bjorken on vector fields, we construct an effective Lagrangian which combines the unified guage theory of Weinberg and Salam for the weak and electromagnetic interactions of leptons and quarks and the asymptotically free gauge theory of Gross, Wilczek, and Politzer for the strong interaction of quarks. The photon, weak vector bosons, and Higgs scalars appear as composites of lepton-antilepton or quark-antiquark pairs, while the color-octer gluons appear as composites of quark-antiquark pairs. As a result, the Weinberg angle is determined to be ${sin}^{2}{\ensuremath{\theta}}_{W} = \frac{3}{8}$ for fractionally charged quarks, which coincides with the prediction of Georgi and Glashow in their unified SU(5) gauge model. The gluon coupling constant is also determined to be 8/3 times the fine-structure constant. The masses of the weak vector bosons and physical Higgs scalars are related to those of leptons and quarks. We also propose a unified spinor-subquark model in which the gauge bosons and Higgs scalars as well as leptons and quarks are all composites of subquarks of spin 1/2. In such a model, we predict, among other things, the mass of the charged weak vector bosons to be approximately $\sqrt{3}$ times the subquark mass. From these results, we strongly suggest that there exist much heavier leptons and/or quarks whose masses reach or go beyond the weak-vector-boson masses or that there exist heavy subquarks whose pair-production threshold lies very close to the weak-vector-boson masses.
TL;DR: In this paper, a new method for obtaining from volcanic surface features the orientations of the principal tectonic stresses is applied to Aleutian and Alaskan volcanoes, based on the recognition of the preferred orientation of radial and parallel dike swarms, primarily using the distribution of monogenetic craters including flank volcanoes.
Abstract: A new method for obtaining from volcanic surface features the orientations of the principal tectonic stresses is applied to Aleutian and Alaskan volcanoes. The underlying concept for this method is that flank eruptions for polygenetic volcanoes can be regarded as the result of a large-scale natural magmafracturing experiment. The method essentially relies on the recognition of the preferred orientation of radial and parallel dike swarms, primarily using the distribution of monogenetic craters including flank volcanoes. Since dikes tend to propagate in a direction normal to the minimum principal stress (T-axis), the method primarily yields the direction of the maximum horizontal compression (MHC) of regional origin. The direction of the MHC may correspond to either the maximum (P-axis) or intermediate (B-axis) principal stress.
01 Jan 1977
TL;DR: The present data are consistent with the replisome model in which several gene products participate in the replication apparatus and the reg mutations are dominant over reg+ in all cases studied.
TL;DR: It is concluded that bacteria are classified into glycolyl type or acetyl type relative to their cell-wall acyl type, which can be easily decided by estimation of glycoell group in the whole bacterial cells.
Abstract: A simple and practical method was studied to identify the acyl type of bacterial cell wall. This method is based on the determination of glycolic acid derived from the acid hydrolysis of a small amount of bacterial cells. The devised system with micro-columns was useful for quantitative separation of glycolic acid from complex materials in cell hydrolysate, and glycolic acid was determined by colorimetric method of Calkins. Experiments showed that about 50 to 60nmol of glycolyl residue was present in 1mg dry cells in strains such as Corynebacterium equi AJ 1402 (ATCC 6939), Brevibacterium imperiale AJ 1446 (IAM 1654), and Brev. testaceum AJ 1464 (IAM 1537), but the acid was scarcely found in Coryn. diphtheriae AJ 1414 (ATCC 11913), Nocardia madurae AJ 9136 (NRRL B-2127), and so on. No acyl group other than glycolyl and acetyl residues or only acetyl group was detected in the purified cell wall of various bacteria tested.From these results it is concluded that bacteria are classified into glycolyl type or acetyl type relative to their cell-wall acyl type, which can be easily decided by estimation of glycolyl group in the whole bacterial cells.
TL;DR: In this article, it was shown from a general point of view that the coexistence of ferro-and antiferromagnetism with a symmetry-breaking is possible in certain itinerant electron systems where the wave vector dependent susceptibility χ q 0 without the electron-electron interaction has two peaks at q = 0 and q = Q, the Antiferromagnetic vector.
TL;DR: In this article, the authors performed in situ observations with an electron microscope of the nucleation and growth of α-martensites induced by plastic deformation in 18/8 stainless steel.
TL;DR: It is postulated that these neurons are inhibitory in nature and cause the IPSPs in contralateral abducens motoneurons at the quick inhibitory phase of vestibular nystagmus.
Abstract: The medial brain stem was explored mainly in the vicinity of the abducens nucleus to find interneurons related to the quick phase of vestibular nystagmus in the cat. Most neurons exhibiting a burst of spikes specifically at the quick phase of nystagmus directed to the ipsilateral side were found in the dorsomedial part of the reticular formation caudal to the abducens nucleus and lateral to the medial longitudinal fasciculus. The burst spikes were preceded by a negative field potential which was fairly localized in the above region. These neurons were activated antidromically from the contralateral and not from the ipsilateral abducens nucleus. The effective sites for antidromic activation showed a patch-like distribution in the abducens nucleus, indicating their axonal branching within the nucleus. Simultaneous recording of spikes of these neurons and the field potential in the contralateral abducens nucleus showed that a spike burst of each neuron began fairly synchronously with the onset of steep positive field potential in the abducens nucleus at the quick inhibitory phase of motoneurons. Microstimulation at the region where these neurons were located induced monosynaptic IPSPs in the contralateral abducens motoneurons. It is thus postulated that these neurons are inhibitory in nature and cause the IPSPs in contralateral abducens motoneurons at the quick inhibitory phase of vestibular nystagmus. The burst inhibitory neurons were activated polysynaptically from the ipsilateral vestibular nerve and monosynaptically from the contralateral superior colliculus or the ipsilateral pontine reticular formation at the level of P2–P6.