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M Shinozuka

Publications and source records attributed to M Shinozuka.

18 recordsLinked to original sources
PubMed2000

Accuracy of chaos synchronization in Nd:YVO(4) microchip lasers

Synchronization of chaotic oscillations generated in two Nd:YVO(4) microchip lasers is experimentally and numerically demonstrated with master-slave coupling schemes. The synchronization performance under some parameter mismatch between the two lasers is quantitatively characterized. Synchronization is always achieved when the lasing frequency of the slave laser is matched to that of the master laser through injection locking. Accurate synchronization of chaos at an average intensity error of less than 2% is attained and maintained for tens of hours. The modulation parameters of the two lasers do not need to be matched for synchronization when the injection power is at a sufficiently high level, because chaos synchronization is based on its injection-locking performance. For accurate synchronization in multimode lasers, the power distribution among longitudinal modes needs to be matched.

Journal Article↗
PubMed1991

Computer simulations of chondrocytic clone behaviour in rabbit growth plates.

The growth behaviour of chondrocytic clones in the cell columns of the proximal tibial growth plates of young rabbits was modelled in computer simulations. Simulations were performed, modelling either clones in large groups of columns or clones in one single column. The former were based on morphological data and measurements of cell columns from an earlier study while the latter utilised previous findings of cellular kinetics in rabbit growth plates. Simulation results that resembled most closely the actual observations on rabbit growth plates were those in which a distribution of values was assumed both for clone length (ranging from 1000 to 2000 microns) and for the lengths of the discontinuities between clones. When the assumption was made in the models that the disappearing (metaphyseal) end of an 'old' clone moved more rapidly than the developing (epiphyseal) end of a 'new' clone, replacing the former, the length of the discontinuity between these two clones increased with time. This assumption, which could be modelled in the simulations of clones in a single column based on cell growth behaviour, was found to provide an explanation for an earlier finding that there are more short columns at the epiphyseal side than at the metaphyseal side of a growth plate.

Animals↗
PubMed1990

Numerical simulation of the crown of an incisiform tooth by conformal and polynomial regression mapping of a simple model.

We present a simple bowl-shaped model in the complex plane for the enamel and dentin structure of a tooth. Isochronous mode lines, and path lines representing the paths followed by individual ameloblasts and odontoblasts, form a simple regular mesh in the model. After the conformal map W = Z2, the transformed model is remarkably tooth like. To further improve the simulation of the crown of an incisiform tooth in particular, we compare our results to our own data from actual teeth and data from the literature. This leads us (a) to adjust the initial model so that the mesh of mode and path lines intersects the boundary of the tooth in a realistic way, and (b) to refine the mapping using least-squares regression to fit polynomial functions of Z and W to the available data.

Computer Simulation↗
PubMed1987

Morphological analysis and computer-aided, three dimensional reconstruction of chondrocytic columns in rabbit growth plates.

Proximal tibial growth plates of New Zealand white rabbits were serially sectioned in parasagittal and horizontal planes for three dimensional, light microscopic analysis of the chondrocytic columns. A total of 431 columns was analysed. Of these, 258 columns extended through the full height of the growth plate. The remaining columns were considerably shorter, being located either predominantly in the epiphyseal half of the growth plate (100) or in the metaphyseal half of the growth plate (73). The epiphyseal and metaphyseal columns were found in clusters in the plate. Some columns in all three groups had interruptions along their length, while others had duplications. Computer-aided, three dimensional graphic reconstructions were prepared of a selected group of columns. The reconstructions illustrated the variability in the morphology and the dimensions of the neighbouring chondrocytic columns. The observations suggest that chondrocytic columns in rabbit growth plates are replaced regularly and that the small cell zone may play an important role as the cellular source for column renewal.

Animals↗
PubMed1985

Finite element method modeling of craniofacial growth.

The application of the concepts of continuum mechanics and of the numerical techniques of the finite element method permits the development of a new and potentially clinically useful method of describing craniofacial skeletal growth. This new method differs from those associated with customary roentgenographic cephalometry in that its descriptions and analyses are invariant; that is, they are independent of any method of registration and superimposition. Such invariance avoids the principal geometric constraint explicit in all analytical methods associated with conventional roentgenographic cephalometry. The conceptual and mathematical bases of the finite element method (FEM) are presented and illustrated by the numerical and graphic descriptions of the two-dimensional growth of the rat skull, for which two sets of longitudinal growth data are used. In practice, the FEM permits analysis of the skull at a scale significantly finer than previously possible, by considering cranial structure as consisting of a relatively large number of contiguous finite elements. For each such element, independently, it is then possible to describe and depict both the magnitude and the direction of temporal size and shape changes occurring in that element relative to itself at some initial time. It is emphasized that such descriptions are completely independent of any local reference frame.

Aging↗
PubMed1984

A stochastic-mechanical model of longitudinal long bone growth.

A typical mammalian long bone will increase in length during the growth phase of the individual. This increase in length does not occur uniformly throughout the bone, since bone tissue is incapable of internal expansion after formation. The growth occurs at two, disc-shaped, regions near either end of the long bone. These regions are called growth plates. These plates are located between the osseous shaft (diaphysis) and osseous tip (epiphysis) whose bone tissues are discontinuous. The present study develops a stochastic-mechanical model for such a bone growth and demonstrates the capability of the model to reproduce the observed overall behavior of longitudinal long bone growth based on realistic information of cellular mitosis, growth and ossification. A numerical analysis was performed on the model under the assumption that the number of cells in the proliferation zone remains constant throughout the growth period. The growth curves thus obtained compare favorably with those growth curves proposed elsewhere essentially on the basis of phenomenological observation. The present model can demonstrate the effects of such parameters as the proliferation rate, initial age distribution and compressive stress on the growth. More importantly, the stochastic-mechanical model so developed permits one to incorporate further experimental evidence and statistical observation at the cellular level into the analysis to improve the solutions.

Animals↗
PubMed1984

An allometric network model of craniofacial growth.

This study of cranial skeletal growth kinematics details the conceptual principles underlying the development of an allometric network model of such growth. This model is tested by the analysis of longitudinal rat and cross-sectional human growth data and by comparison of this model with a previously described allometric centered model. It is shown that the network model is superior to the centered model in three ways: (1) The allometric network model permits growth prediction when allometric constants are known; (2) the network model has significantly smaller errors than the centered model; and (3) the network model is capable of displaying growth kinematics of both the neural and facial skulls while in time there are marked transformations, such as relative rotations of two sets of cranial anatomic points.

Adolescent↗
PubMed1983

Statistical testing of an allometric centered model of craniofacial growth.

An allometric centered model of craniofacial growth was tested by several computer-assisted statistical methods on the pure longitudinal growth data of twenty-four close-bred female rats and on cross-sectional human cranial growth data. The study demonstrated that such a model was heuristic and, being incapable of exact definition, was deemed inappropriate for further use in modeling of craniofacial skeletal growth. The necessity for vigorous testing of any hypothesis concerning the modeling of craniofacial growth is stressed.

Adolescent↗