2000 Fiscal Year Final Research Report Summary
Experiments of Dissipative Systems with Many Degrees of Freedom (from the view point of nonlinear dynamics and fluctuations)
| Project/Area Number |
11440119
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物性一般(含基礎論)
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| Research Institution | University of Tokyo (2000)
Tohoku University (1999) |
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Principal Investigator |
SANO Masaki University of Tokyo, Physics Department, Prof., 大学院・理学系研究科, 教授 (40150263)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Dissipative Systems / Rayleigh-Benard Convection / Developed Turbulence / Hard Turbulence / Cultured Neural Networks / Synchronous Firin / Principal Component Analysis / Glial Cell |
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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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