A note on brane boxes at finite string coupling
  We consider N=1 supersymmetric SU(N_c) gauge theories, using the type IIB brane construction recently proposed by Hanany and Zaffaroni. At non-zero string coupling, we find that the bending of branes imposes consistency conditions that allow only non-anomalous gauge theories with stable vacua, i.e., N_f >= N_c, to be constructed. We find qualitative differences between the brane configurations for N_f <= 3N_c and N_f > 3N_c, corresponding to asymptotically free and infrared free theories respectively. We also discuss some properties of the brane configurations that may be relevant to constructing Seiberg's duality in this framework. 
Eric G. Gimon, Martin Gremm