Austin. It A wall of funnels concentrates swimming bacteria. I. Bacterial. 189. 8704-8707 (2007). 40. Mannik. L. Thiessen. It. Galeda. P.. Keymer. I. E. & Dekker• C. Bacterial growth and motility in sub-micron constrictions. Proc. Nati. Acad. Set USA 106. 14861-14866 (2009). 41. Ruston. It. Garen. M. & Stocker.