Criterion for purely elastic Taylor-Couette instability in the flows of shear-banding fluids M. A. Fardin, T. J. Ober, C. Gay, G. Grégoire, G. H. McKinley and S. Lerouge EPL, 96 4 (2011) 44004 Published online: 09 November 2011 DOI: 10.1209/0295-5075/96/44004