References

1. M. Aizenman, G. Grimmett, Strict monotonicity for critical points in percolation and ferromagnetic models, J. Stat. Phys. 63 (1991), 817--835. Math. Review 92i:82060
2. R. M. Bradley, A Comment on ``Ring Dynamics and percolation in an excitable medium,'' J. Chem. Phys. 86 (1987), 7245--7246. Math. Review number not available.
3. R. Durrett, D. Griffeath, Asymptotic behavior of excitable cellular automata, Experimental Math. 2 (1993), 184--208. Math. Review 95e:58095
4. R. Durrett, C. Neuhauser, Epidemic with recovery in d=2, Ann. Appl. Prob. 1 (1991), 189--206. Math. Review 92k:60222
5. R. Durrett, J. E. Steif, Some rigorous results for the Greenberg-Hastings model, J. Theor. Prob. 4 (1991), 669--690. Math. Review 93h:60162
6. R. Durrett, Multicolor particle systems with large threshold and range, J. Theor. Prob. 5 (1992), 127--152. Math. Review 93b:60227
7. R. Fisch, J. Gravner, D. Griffeath, Threshold-range scaling of excitable cellular automata, Statistic and Computing 1 (1991), 23--39. Math. Review number not available.
8. R. Fisch, J. Gravner, D. Griffeath, Metastability in the Greenberg--Hastings model, Ann. Appl. Prob. 3 (1993), 935--967. Math. Review 95f:60120
9. S. Fraser, R. Kapral, Ring dynamics and percolation in an excitable medium, J. Chem. Phys. 85 (1986), 5682--5688. Math. Review 87k:82085
10. J. M. Greenberg, S. P. Hastings, Spatial patterns for discrete models of diffusion in exitable media, SIAM J. Appl. Math. 34 (1978), 515--523. Math. Review 58#4408
11. J. Gravner, Mathematical aspects of excitable media, Ph. D. Thesis, University of Wisconsin, 1991. Math. Review number not available.
12. J. Gravner, The boundary of iterates in Euclidean growth models, Trans. Amer. Math. Soc., to appear. Math. Review 1 370 643
13. J. Gravner, Recurrent ring dynamics in two--dimensional excitable cellular automata, submitted. Math. Review number not available.
14. J. Gravner, D. Griffeath, First passage times for threshold growth dynamics on Z^2 Ann. Prob., to appear. Math. Review number not available.
15. G. Grimmett, ``Percolation,'' Springer-Verlag, 1989. Math. Review 90j:60109
16. W.A. Johnson and R.F. Mehl, Reaction kinetics in processes of nucleation and growth, Trans. A.I.M.M.E. 135 (1939), 416--458. Math. Review number not available.
17. R. Kapral, M. Weinberg, Phase transformation kinetics in finite inhomogenuosly nucleated systems, J. Chem. Phys. 11 (1989), 7146--7152. Math. Review number not available.
18. R. Kapral, Discrete models for chemically reacting systems, J. Math. Chem. 6 (1991), 113--163. Math. Review 1 101 758
19. H. Kesten, ``Percolation Theory for Mathematicians,'' Birkhauser, 1982. Math. Review 84i:60145
20. M. D. Penrose, Single linkage clustering and continuum percolation, J. of Multivariate Analysis 53(1995), 90--104. Math. Review 96e:62099
21. R. Roy, The Russo--Seymour--Welsh theorem and the equality of critical densities and the ``dual'' critical densities for continuum percolation on R^2, Ann. Prob. 18 (1990), 1563--1575. Math. Review 92a:60209
22. J. M. Smith, A. L. Ritzenberg, R. J. Cohen, Percolation theory and cardiac conduction, Computers in Cardiology (1984), 175--178. Math. Review number not available.
23. J. Steif, Two applications of percolation to cellular automata, J. Stat. Phys. 78 (1995), 1325--1335. Math. Review 96f:82027
24. S. J. Willson, On convergence of configurations, Discrete Mathematics 23 (1978), 279--300. Math. Review 80g:68074
25. N. Wiener, A. Rosenbluth, The mathematical formulation of the problem of conduction of impulses in a network of connected excitable elements, specifically in cardiac muscle, Arch. Inst. Cardiol. Mexico 16 (1946), 205--265. Math. Review 9,604a
26. J. R. Weimar, J. J. Tyson, L. T. Watson, Third generation cellular automaton for modeling excitable media, Physica D 55 (1992), 328--339. Math. Review 93b:65200
27. S. A. Zuev, A. T. Sidorenko, Continuous models of percolation theory I, II, Theoretical and Mathematical Physics 62 (1985), 51--58, 171--177. Math. Review 86j:82044a Math. Review 86j:82044b