e periodic orbits have been demonstrated in geometric reconstructions of real data series generated by a 40+ component chemical reaction (Lathrop and Kostelich, 1989), in response to natural stimuli in the time dependent behavior of the crayfish caudal photoreceptor (Pei and Moss, 1996) and in the interburst

Yorke, J. (1973) On the existence of invariant measures for piecewise monotonic transformations. Trans. Amer. Math. Soc. 186:481-488 Lathrop, D.P., Kostelich, E.J. (1989) Characterization of an experimental strange attractor by periodic orbirts. Phys. Rev. A40:4028-4031 269 HOUSE_OVERSIGHT_013769 --- PA