1. When Noise Is a Blessing and Not an Annoyance
Stochastic Resonance in a Spatially Extended Chemical System

2. What is Stochastic Resonance (SR)?
SR is a mechanism through which a weak otherwise undetectable periodic signal becomes detectable
What is Spatiotemporal Stochastic Resonance (STSR)?
Spatial excitation patterns in an extended medium display resonance-type dependence on the noise-variance with the patterns being optimal at intermediate noise level

3. General introduction to SR
Outline
General introduction to SR
Demonstration
Examples
The Chemical System – Belousov Zhabotinsky Reaction
Demonstration
Chemical reactions
Mechanism (Oregonator Model)
Simplified mechanism (Tyson-Fife scaling)
Results
STSR with colored noise – single wave
STSR with white noise – single wave
STSR with white noise – wave trains

4. Photosensitive Belousov-Zhabotinsky-reaction
Components:
NaBrO3
H2SO4
Malonic acid/Bromomalonic acid
Ru(Bpy)32+ catalyst
Key intermediates:
HBrO2
Br-
Activator
Inhibitor
Ru(Bpy)32+
Bromomalonic acid
Br-
l = 460 nm

5. Excitability Light intensity
Photosensitive BZ-reaction
Excitability
Light intensity
Steady state
Excitable
Oscillatory
More light
Less light

6. Periodic signal
Threshold
Noise + Signal
Events:
Fourier spectrum:

8. A little history
Proposed explanation of the periodic recurrences of the Earth’s ice ages (1981)
First experimental evidence: in a noise-driven electronic circuit (Schmitt trigger)
Improved visual perception
Crayfish mechanoreceptor (hair cell)

9. Improve visual perception
Enrico Simonotto

10. Crayfish mechanoreceptor (hair cell)

11.  Tyson-Fife Scaling of the Oregonator Model
(modified to account for photosensitivity) 

12. Belousov-Zhabotinsky Reaction

13. Excitability
Light intensity
Photosensitive BZ-reaction

14. Experimental Setup

16. low excitability - no wave support
high excitability
(dark)
Excitability
255
100%
noise
low excitability - no wave support
(bright)
sub-excitable

17. Experimental Results Noise level = 0 Noise level = 30%

18. SNR as a function of cluster size

19. Numerical Results Noise level = 0 Noise level = 30% Noise level = 60%

20. Where to go? Refresh rate dependence
Cluster size/shape/density dependence
Truly white noise
Time series for each cluster

21. Acknowledgement
Jichang Wang
Kenneth Showalter
Eugene Mihaliuk