  For most stochastic dynamical systems, variables which are tightly regulated
tend to respond slowly to external changes. This idea is often discussed for
applicable systems, within a linear response regime, through the Fluctuation
Dissipation Theorem (FDT). In a previous paper, we proposed a phenomenological
model for the response of the cell cycle duration distribution to environmental
changes which correlated the width of this distribution to response efficiency
when FDT was not applicable. Here we emphasize how that model may be used to
illustrate this general principle, that the stochasticity of a variable while
inversely proportional to stability is often directly proportional to lability.
Comparisons are made between this discrete-time model and the simple harmonic
oscillator. We then consider a simple continuous dynamical system, the 'Active
Oscillator', which illustrates this principle in another fashion.
