"Although the prevalence of L. monocytogenes and Salmonella was low, these pathogens represent a potential risk to consumers of raw milk and raw milk products."
Paper in which we describe how an artificial chemistry on a planar graph easily generates islands of activity with barriers with much lower activity between them
Pietro Speroni di Fenizio: "Artificial Chemistries (an introduction) " Bulletin of the European Association for Theoretical Computer Science 76(2002),128-141.