Type IIA String and Matrix String on PP-wave
  We study type IIA string theories on the pp-waves with 24 supercharges. The type IIA pp-wave backgrounds are derived from the maximally supersymmetric pp-wave solution in eleven dimensions through the toroidal compactification on the spatial isometry directions. The associated actions of type IIA strings are obtained by using these metrics and other background fields of the type IIA supergravities on the one hand. On the other hand, we derive these theories from D=11 supermembrane on the pp-wave via double dimensional reduction for the spatial isometry directions. The resulting actions agree with those of type IIA strings obtained in the study of the supergravities. Also, the action of the matrix string is written down. Moreover, the quantization of closed and open strings is discussed. In particular, we study Dp-branes allowed in one of the type IIA theories. 
Katsuyuki Sugiyama and Kentaroh Yoshida (Kyoto Univ.)