Critical timescales and time intervals for coupled linear processes


  • Matthew Joseph Simpson Queensland University of Technology
  • Adam John Ellery Queensland University of Technology
  • Scott William McCue Queensland University of Technology
  • Ruth Elizabeth Baker Center for Mathematical Biology, University of Oxford



reaction–diffusion equation, coupled reaction–diffusion equations, steady state, critical time


In 1991, McNabb introduced the concept of mean action time (MAT) as a finite measure of the time required for a diffusive process to effectively reach steady state. Although this concept was initially adopted by others within the Australian and New Zealand applied mathematics community, it appears to have had little use outside this region until very recently, when in 2010 Berezhkovskii and co-workers [A. M. Berezhkovskii, C. Sample and S. Y. Shvartsman, “How long does it take to establish a morphogen gradient?†Biophys. J. 99 (2010) L59–L61] rediscovered the concept of MAT in their study of morphogen gradient formation. All previous work in this area has been limited to studying single-species differential equations, such as the linear advection–diffusion– reaction equation. Here we generalize the concept of MAT by showing how the theory can be applied to coupled linear processes. We begin by studying coupled ordinary differential equations and extend our approach to coupled partial differential equations. Our new results have broad applications, for example the analysis of models describing coupled chemical decay and cell differentiation processes. doi:10.1017/S1446181113000059

Author Biographies

Matthew Joseph Simpson, Queensland University of Technology

Senior Lecturer in Mathematics

Adam John Ellery, Queensland University of Technology

PhD Student

Scott William McCue, Queensland University of Technology

Associate Professor

Ruth Elizabeth Baker, Center for Mathematical Biology, University of Oxford






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