Equation Icon  a 3 ξ (τ) = (τ,0,0,iξ ), (260 ) a ˆ ¯ √τ-- i- 3 0 uB = ξ (τ)la(ζ, ζ) ≡ 2 − 2ξ Y 1,3, ¯ 3 1 L(uB, ζ,ζ) = iξIY1,3, Ji = Si = MBc ξ3δi3 = MBc (0,0,ξ3) = MBc ξiI.