| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2000: ¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1999: ¥8,200,000 (Direct Cost: ¥8,200,000)
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| Research Abstract |
We selected two prototype experimental systems from dissipative systems with many degrees of freedom. One is the experiment of fully developed thermal turbulence. The other is an experiment on networks of cultured neural cells.
In the first study, thermal turbulence, we developed Rayleigh-Benard convection cell that enables us to explore one of the highest Reynolds numbers in turbulent free convection by using mercury, a low Prandtl number (Pr) fluid. We attained 10^<11> in Rayleigh number (Ra) and 5x10^5 in Reynolds number for the low Prandtl number fluid (Pr=0.024), and found that two boundary layers are inverted unlike with other fluids (Pr>=1). The scaling exponent of Nusselt number with Ra was 0.29+-0.01, which is close to that of hard turbulence. Two boundary layers match and shrink with the scaling exponent close to -0.29. Therefore theoretically predicted ultimate scaling, 1/2, did not observed even the two boundary layers have crossed. This leads a conjecture that the ultimate scaling regime may not exist.
In the second study, we made dissociated culture of brain cells, which are dissected from cortex of rat embryo (E17). Neuron and glia cells grow on the glass plate and develop highly connected network structures. By using Ca^<2+> sensitive fluorescent dye, Ca^<2+> activities of a few hundreds of cells were optically measured simultaneously. We found synchronous bursting Ca^<2+> oscillation in the networks, and classified collective dynamical behavior. Connectivity and structure of the network were evaluated by using monochronal antibody staining. Evolution of distribution function of correlation coefficients between neuron-neuron, neuron-glia, and glia-glia, was firstly quantified to characterize the developmental process of the networks.
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