Equation Icon  χ (Ω )χ (Ω) [ ] ˆO (Ω ) = ˆO (0)(Ω) + ----xx-----OF------ G (Ω ) + ˆF (0)(Ω) , (135 ) 1 − χxx(Ω )χFF (Ω) ˆ ---------1-------- [ ˆ (0) ] F (Ω ) = 1 − χ (Ω )χ (Ω) F (Ω) + χF F(Ω)χxx (Ω )G (Ω) , (136 ) xx FF [ ] ˆx (Ω ) = ------χxx(Ω-)----- G (Ω ) + ˆF(0)(Ω ) . (137 ) 1 − χxx(Ω )χFF (Ω)