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  • 1
    Electronic Resource
    Electronic Resource
    Possible Mechanism of Precursory Seismic Quiescence: Regional Stress Relaxation due to Preseismic Sliding (1997)
    Springer
    Pure and applied geophysics 150 (1997), S. 249-267 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Seismic quiescence, numerical simulation, rate- and state-dependent friction, preseismic sliding, stress relaxation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —We propose a new model to physically explain the seismic quiescence precursory to a large interplate earthquake. A numerical simulation is performed to quantitatively examine possible stress changes prior to a great interplate earthquake in a subduction zone. In the present study, the frictional force following a laboratory-derived friction law, in which the friction coefficient is dependent on slip rate and slip history, is assumed to act on a dip-slip fault plane of infinite width in a uniform elastic half-space. The values of friction parameters are determined so that the result of numerical simulation may explain some properties of great interplate earthquakes in subduction zones, such as the recurrence interval and the seismic coupling coefficient. The result of simulation reveals that significant quasi-stable sliding occurs prior to a great earthquake and, accordingly, stresses are changed on and around the plate boundary. In a relatively wide area of the overriding continental plate, the compres sional horizontal-stress perpendicular to the trench axis is decreased for a few years before the occurrence of a great earthquake. This decrease in regional compressional stress may account for the appearance of seismic quiescence prior to a great interplate earthquake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050075
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  • 2
    Electronic Resource
    Electronic Resource
    Nonuniform and Unsteady Sliding of a Plate Boundary in a Great Earthquake Cycle: A Numerical Simulation Using a Laboratory-derived Friction Law (1999)
    Springer
    Pure and applied geophysics 155 (1999), S. 93-118 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Rate- and state-dependent friction law, subduction zone, seismic activity, aseismic sliding.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —A numerical study is conducted to simulate complicated sliding behavior and earthquake activity on a subducting plate boundary. A 2-D model of a uniform elastic half-space with a semi-infinite thrust fault is set up, and the frictional stress prescribed by a rate- and state-dependent friction law is assumed to act on the plate boundary fault. Spatial nonuniformity of friction parameters representing rate-dependence of friction and of slip-dependence of friction are introduced in the model to obtain complicated sliding behavior in the numerical simulation. Analogs of great earthquakes that break the entire seismogenic plate boundary repeatedly occur at a constant time interval. Smaller events of seismic or aseismic sliding occur during a great earthquake cycle. Regions of rate-strengthening of friction and of a large characteristic distance in slip-dependence of friction behave as barriers or asperities. Rupture propagation is often arrested in such a region and a great earthquake occurs later when the region is broken. The variety of earthquake activity observed in many regions along real plate boundaries may be explained by similar nonuniformity in friction parameters. Conversely, the friction parameters on plate boundaries might be estimated from comparison of theoretical simulations with observations of earthquake activity. Simulation results indicate that spatiotemporal variation in stress due to aseismic sliding may play an important part in generating earthquakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050256
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  • 3
    Electronic Resource
    Electronic Resource
    The Variation of Stresses due to Aseismic Sliding and its Effect on Seismic Activity (1999)
    Springer
    Pure and applied geophysics 155 (1999), S. 425-442 
    Details
    ISSN: 1420-9136
    Keywords: Key Words: A rate- and state-dependent friction law, seismic cycle, precursory seismic quiescence, postseismic sliding, intermediate-depth earthquake, episodic sliding.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract — Numerical simulation of recurring large interplate earthquakes in a subduction zone is conducted to explore the effects of aseismic sliding on the variation of stresses and the activity of small earthquakes. The frictional force obeying a rate- and state-dependent friction law is assumed to act on the plate interface in a 2-D model of uniform elastic half-space. The simulation results show that large earthquakes repeatedly occur at a constant time interval on a shallow part of the plate interface and that aseismic sliding migrates from the upper aseismic zone as well as from the lower aseismic zone into the central part of the seismogenic zone before the occurrence of a large interplate earthquake. This spatiotemporal variation of aseismic sliding significantly perturbs the stresses in the overriding plate and in the subducting oceanic plate, leading to the precursory seismic quiescence in the overriding plate and the activation of the intermediate-depth earthquakes of down-dip tension type. After the occurrence of a large interplate earthquake, the activity of the intermediate-depth earthquakes of down-dip compression type in the subducting slab is expected to increase and migrate downward. This is because the downward propagation of postseismic sliding causes the downward migration of compressional-stress increase in the down-dip direction of the plate interface. The simulation result further indicates that episodic events of aseismic sliding may occur when the spatial distributions of friction parameters are significantly nonuniform. The variation of stresses due to episodic sliding is expected to cause seismicity changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050273
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  • 4
    Electronic Resource
    Electronic Resource
    Recognition of a Locked State in Plate Subduction from Microearthquake Seismicity (1999)
    Springer
    Pure and applied geophysics 155 (1999), S. 669-687 
    Details
    ISSN: 1420-9136
    Keywords: Key Words: Locked subduction, microearthquake seismicity, frictional sliding.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —A tectonic state of a locked subduction is considered to be a possible source of a future interplate earthquake. Discriminating an actually locked state to verify its extent is therefore essential in constructing an accurate prospect against the forthcoming earthquake. Micorearthquake seismicity is an effective tool for such an analysis because it is considered to be a faithful indicator of the stress state, and is expected to exhibit a characteristic pattern in the area where the locked state in the subduction appears with a certain stress concentration. Focusing on the microearthquake seismicity around the Tokai district in central Japan, where a large interplate earthquake is feared to occur, we tried to identify such an area of locked subduction on the Philippine Sea plate, possibly related to the future earthquake. We investigated the microearthquake seismicity from various perspectives. First, the hypocenter distribution was analyzed to identify the extent of the locked area. The characteristic profile of the distribution was presumed to represent a stress concentrated area induced from the mechanical contact between both plates. The second approach is to interpret stress patterns reflected in focal mechanisms. The locked state was recognized and verified by a comparison of the P-axis distribution pattern with that expected from a model imaging a partially locked subduction. The third approach is to monitor the temporal change of the seismic wave spectrum. Analyzing predominant frequencies of P and S waves and monitoring their changes for a period of 10 years, we found a trend of gradual increase common to both waves. This means an increase of stress drop in microfracturings, and in its turn implies accumulation of stress around the focus area. The rate of the stress change converted from the frequency change was compared with the result derived from a numerical simulation. The simulation, performed on the basis of a constitutive friction law for a stick sliding on the plate interface, computed a changing rate of the maximum shear stress around the locked zone and showed its spatial variation along the subduction axis. Thus the simulated result indicated a certain compatibility with the observed one. Although ambiguities and uncertainties still exist in the study, all the results derived here seem to indicate an identical conclusion that the plate subduction is actually locked in this region at present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050282
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  • 5
    Electronic Resource
    Electronic Resource
    A new cultivation method of fungi or mycelia (1988)
    Springer
    Bioprocess and biosystems engineering 3 (1988), S. 63-68 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The conventional penicillin submerged culture has several drawbacks: filamentous fungi solidify into pellets or become pulpy, which has so far had bad effects on the separation of penicillin from the broth, on the monitoring and controlling of the culture system as well as on the productivity of penicillin. By using polyurethane foams as a carrier for the fungi Penicillium chrysogenum, the authors have studied a novel cultivation method for this microorganism. The following results were obtained: 1. The effect of urethane foams on the growth characteristics of Penicillium chrysogenum was studied. It was found that the microorganism crept into the carrier, then formed a biofilm of 0.45 mm in thickness on the surface layer of the carrier. 2. The use of urethane foams had the effect of improving not only the mass transfer rates of various nutrients, but also that of oxygen in the culture system. Six times as much penicillin could be produced as is obtainable by traditional cultivation methods. 3. An operational strategy for the addition of polyurethane Toams to the culture medium could be developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369329
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  • 6
    Electronic Resource
    Electronic Resource
    Postnatal development of the striate cortical projection onto the extrageniculate visual thalamus in the cat: an HRP study (1987)
    Springer
    Experimental brain research 67 (1987), S. 119-126 
    Details
    ISSN: 1432-1106
    Keywords: Lateral posterior nucleus ; Corticothalamic projection ; Regressive phenomenon ; Kittens ; Area 17
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The postnatal development of the striate cortical projection onto the extrageniculate visual thalamus was examined by using the orthograde and retrograde HRP methods. At birth, the projection is present, and fibres of the projection terminate in the lateral part of the lateral posterior nucleus. A rough topographical arrangement of the projection is already established. Neurones that give rise to the projection are located exclusively in layer V from birth onward. However, the neurones are much more densely packed at birth than in adult cats. The packing density of the neurones decreases rapidly during the second postnatal week, and afterwards continues to become gradually lower. In the meantime, the cross sectional area of the neurones increases sharply during the second postnatal week. These findings suggest that striate cortical neurones projecting onto the lateral posterior nucleus rapidly complete the final stages of their maturation shortly after the normal opening of the eyelids, and during this time some of these neurones undergo axonal elimination or neuronal death, or both.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269460
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  • 7
    Electronic Resource
    Electronic Resource
    The postnatal development of thalamocortical projections from the pulvinar in the cat (1987)
    Springer
    Experimental brain research 68 (1987), S. 533-540 
    Details
    ISSN: 1432-1106
    Keywords: Extrageniculate visual system ; Association cortex ; Kittens ; HRP ; Laminar field potential ; Layer I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The postnatal development of thalamocortical projections from the pulvinar to an association cortex of the cat, the crown of the middle suprasylvian gyrus, was studied by using both HRP and evoked field potentials. From birth onward, the pulvinar sends dense fibres to this cortical area, but the cortical laminar distribution of the afferents was found to change markedly with aging. An orthograde HRP study showed that at birth and up to 2 weeks of age, the terminals are distributed mainly in layer I, whereas in adult cats and kittens older than 1 month, the terminals are found largely in and around layer IV and only sparsely in layer I. After HRP injections exclusively into layer I of the crown, numerous thalamic neurones were retrogradely labelled in both the ventroanterior-ventrolateral complex (VA-VL) and the pulvinar in 5-day-old kittens, but in the VAVL alone in 2-month-old kittens. In agreement with these anatomical findings, stimulation of the pulvinar elicited a surface-negative, depth-positive potential in 1-week-old kittens, indicating the existence of a large current sink in layer I; however, it induced a surface-positive, depth-negative potential in 1month-old kittens, reflecting the presence of a strong current sink in the deep cortical layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249797
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  • 8
    Electronic Resource
    Electronic Resource
    Postnatal development of the geniculocortical projection in the cat: Electrophysiological and morphological studies (1983)
    Springer
    Experimental brain research 51 (1983), S. 65-72 
    Details
    ISSN: 1432-1106
    Keywords: Postnatal development ; Geniculocortical projection ; Laminar field potential ; HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using laminar field potential analysis, we examined responses elicited by both photic and optic nerve stimulations in 30 kittens of 0–65 days of age and in three adult cats. In adult cats, the response in the visual cortex on optic nerve stimulation is a wave complex which consists mainly of surface positive-depth negative (sP-dN) potentials. By contrast, the response in neonates consists of two surface negative — depth positive (sN-dP) waves. In 2 weeks, preceding the sN-dP waves, an sP-dN wave appears. As age increases, the sP-dN wave becomes of higher voltage and the sN-dP waves become of lower voltage. Thus, the configuration of the response resembles that of adult cats in 3–4 weeks. Both photic and optic nerve stimulations elicit responses of the same configuration in the same area. The extent of the responsive area is exactly the same at any age as in adult cats. Using the orthograde HRP method, we examined terminals of the geniculocortical afferent in 23 kittens of 0–43 days of age. The density of labeled terminals in layer I is much higher in kittens before 1 week of age (n = 8) than in kittens after 1 month of age (n = 5), whereas the density of labeled terminals in layer IV is higher in the older kittens than in the younger kittens. These electrophysiological and morphological changes are correlated in reference to the maturation of the neuronal circuit in the visual cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236803
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  • 9
    Electronic Resource
    Electronic Resource
    A patient with infantile spasms and low homovanillic acid levels in cerebrospinal fluid: l-dopa dependent seizures? (1989)
    Springer
    European journal of pediatrics 148 (1989), S. 667-668 
    Details
    ISSN: 1432-1076
    Keywords: Infantile spasms ; Pyridoxine ; l-dopa ; Monoamine ; ACTH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 3-month-old female with infantile spasms that responded transiently to pyridoxine and permanently to oral l-dopa. Initial CSF levels of homovanillic acid were low, suggesting disturbed turnover of dopamine. These findings suggest that disturbed brain monoamine metabolism may be causally related to infantile spasms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441530
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  • 10
    Electronic Resource
    Electronic Resource
    Multi-purpose nonlinear optical microscope. Its principle and applications to polar thin-film observation (1999)
    Springer
    Physics of the solid state 41 (1999), S. 688-692 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Multi-purpose nonlinear optical microscope is an optical microscope which images 2D distribution of the optical second harmonic (SH) waves from a specimen. Image contrast can be obtained either by inhomogeneous distribution of nonlinear optical tensor components or by the interference between SH waves from a specimen and a standard plate. This microscope also functions as a fluorescence (FL) microscope, and SH and FL images can be obtained from the same part of a specimen. Absorption and FL spectra from a specific part of a specimen are measured through an optical fiber which connects an ocular with a polychromator. These functions are especially useful for investigation of the J-aggregate state of polar dye molecules. Several photographs taken by the microscope revealed the structure of merocyanine dye/arachidic acid mixed monolayer and the role of bridge ions in the subphase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130850
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