Multicritical behavior of the diluted contact process
  We study a contact process on a two-dimensional square lattice which is diluted by randomly removing bonds with probability p. For p<1/2 and varying birth rate $\lambda$ the model was shown to exhibit a continuous phase transition which belongs to the universality class of strongly disordered directed percolation. The phase transition line terminates in a multicritical point at p=1/2 and $\lambda=\lambda*=3.55(1)$, where the model can be interpreted as a critical directed percolation process running on a critical isotropic percolation cluster. In the present work we study the multicritical point and its neighboorhood by numerical simulations, discussing possible scaling forms which could describe the critical behavior at the transition. 
Silvio R. Dahmen, L. Sittler and H. Hinrichsen