TY - JOUR AU - D. Lazzati AU - C. Blackwell AU - B. Morsony AU - Mitchell Begelman BT - Monthly Notices of the Royal Astronomical Society: Letters DA - Nov-02-2011 DO - 10.1111/j.1745-3933.2010.00984.x PY - 2011 SP - L16 EP - L20 T2 - Monthly Notices of the Royal Astronomical Society: Letters TI - X-ray flares from propagation instabilities in long gamma-ray burst jets VL - 411 ER -