Cluster observations of the mid-altitude cusp under strong northward   Interplanetary Magnetic Field
  This paper has been withdrawn by the author since it has been accepted for publishing in J. Geophys. Res. Please contact the American Geophysical Union for the refereed article. 
Renyu Hu, Yulia V. Bogdanova, Christopher J. Owen, Claire Foullon,   Andrew N. Fazakerley, Henri Reme