| Project/Area Number |
17570136
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | Waseda University |
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Principal Investigator |
TAKAMATSU Atsuko Faculty of Science and Engineering, Associate Professor, 理工学術院, 助教授 (20322670)
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| Co-Investigator(Kenkyū-buntansha) |
KAGAWA Yuki Faculty of Science and Engineering, Reserch Acistant, 理工学術院, 助手 (90409649)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Plamsmodium of Physarum / coupled oscillator system / switching behavior / Chaotic itinerancy / 生物物理 / 真正粘菌 / マイクロデバイス |
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| Research Abstract |
Switching behavior in spatio-temporal oscillating pattern observed in a biological coupled oscillator system constructed with plasmodial slime mold, Physarum polycephalum was investigated.
In first fiscal year, we investigated pattern variations, its observation frequency and switching rules in coupled three oscillator systems. We found those all depend on interactions strength. We start to construct a mathematical model by combining conservation law of protoplasm (total mass of the plasmodium) and ordinary phase equations that commonly used as one of the simplest models for coupled oscillator systems. We found that all the spatio-temporal patterns observed in the two-or three-oscillator systems can be reproduced by this model. However, switching behavior can not be yet.
In second fiscal year, we investigated distributions of residence time in every patterns. The histograms seem to have Gamma-like distribution form but with a sharp peak and a tail on the side of long period. That suggests the attractor of this system has complex structure composed of at least three types of sub-attractors: "Gamma attractor"-involved with several Poisson processes, a "deterministic attractor"-the residence time is deterministic, and a "stable attractor"-each pattern is stable. From these experimental results, we proposed a conjecture as follows: As coupling strength increases, the deterministic attractor appears then followed by the stable attractor, always accompanied with the Gamma attractor. Switching behavior could be caused by regular existence of the Gamma attractor.
The plasmodium shows random spatio-temporal pattern when it is searching food. The switching behavior rather than fixed patterns could be able to generate the spontaneous searching behavior. Mathematical modeling of switching behavior based on these experimental results is one of future works.
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