A different view of the quantum Hall plateau-to-plateau transitions
  We demonstrate experimentally that the transitions between adjacent integer quantum Hall (QH) states are equivalent to a QH-to-insulator transition occurring in the top Landau level, in the presence of an inert background of the other completely filled Landau levels, each contributing a single unit of quantum conductance, $e^{2}/h$, to the total Hall conductance of the system. 
D. Shahar, D.C. Tsui, M. Shayegan (Princeton), E. Shimshoni   (Oranim-Haifa) and S. L. Sondhi (Princeton)