1. The system of equations (7) should read as follows:
  2. The term defining A2 in below equation (15) should read as follows:

where …, A2=1ξ1+βξ22(1+Nr).

  1. In the caption of Fig. 1, “and (b) ϕ=π” should read “and (d) ϕ=π”.

  2. In Section 2, line 6, “… are d1 and d1, respectively).” should read “… are d1 and d2, respectively).”

These corrections have no effect on the results presented in this paper.