Growth of frequently Birkhoff-universal functions of exponential type on   rays
  We consider growth conditions for (frequently) Birkhoff-universal functions of exponential type with respect to the different rays emanating from the origin. For that purpose, we investigate their (conjugate) indicator diagram or, equivalently, their indicator function. Some known results, where growth is measured with respect to the maximum modulus, are extended. 
Hans-Peter Beise
math.CV math.DS