The stratified two-sided jet of Cygnus A - Acceleration and collimationB. Boccardi, T. P. Krichbaum, U. Bach, F. Mertens, E. Ros, W. Alef and J. A. ZensusA&A, 585 (2016) A33DOI: https://doi.org/10.1051/0004-6361/201526985