discriminate normal subjects from those with early glaucoma, but the reconstructed attractor of the steady state visual cortical response to full field flicker demonstrated a statistically significant decrease in D2 (Schmeisser et al, 1993). Marginal qualitative differences in optokinetic nystagmus were quantitatively significant when studied as the Dz of the attractor’s points in patients with vertigo compared with controls (Aasen et al, 1997). Reconstructions of maximum velocity waves from Doppler studies of middle cerebral artery hemodynamics (using phase random “controls”) demonstrated an increase in D2 (and a decrease in 4(+) correlated with age in an adult population (Keuner et al, 1996; Vliegen et al, 1996). D2 served as a sensitive descriptor of functional changes in the EMG from the surface of the biceps muscle, increasing with muscle load and rate of flexion and extension and decreasing with muscle fatigue (Rapp et al, 1993; Nieminen and Takala, 1996; Gupta et al, 1997), suggesting its use in suspected early myotonic dystrophies and myasthenias. Reconstructed time series of stomatognathic motions in high school students with temporomandipular joint syndromes compared with those with malocclusion revealed a specific decrease in Doin the plane of horizontal motion in the former (Morinushi et al, 1998). Time series of plasma growth hormone levels in acromegalic patients with functioning pituitary adenomas manifested a statistically significant increase in Do when compared with age-matched controls (Mandell and Selz, 1997) which corresponded nicely to the reduction in “approximate entropy” (Pincus, 1991a) computed on this same data set (Hartman et al, 1994). On the other hand, comparative in vitro studies of growth hormone release patterns in normal rat pituitary cells and their neoplastically transformed relatives, the GH3 strain, demonstrate a decrease in Do in the latter (Guillemin et al, 1983; Mandell, 1986). The number of examples of the use of D2 on orb