G.  Vozzi, Mazzei, D., Tirella, A., Vozzi, F., and Ahluwalia, A., ?Finite element modelling and design of a concentration gradient generating bioreactor: Application to biological pattern formation and toxicology?, Toxicology in vitro, vol. 24, pp. 1828?1837, 2010 [Online]. Available: http://www.ncbi.nlm.nih.gov/pubmed/20580814