On Multiwavelength Emission and Morphology of Large-Scale Quasar Jets
  We propose that the knots of the large-scale jets in powerful radio sources represent moving and separate portions of the jet matter, with the excess kinetic power. This can explain many morphological properties of quasar jets - like high knot-to-interknot brightness contrasts, frequency-independent knot profiles and almost universal extents of the knot regions - independently of the exact emission mechanisms responsible for producing broad-band jet emission. We briefly discuss a possible connection between this scenario and the idea of highly modulated/intermittent activity of the jet engine. 
L. Stawarz, M. Sikora, M. Ostrowski, M.C. Begelman