E
t
T
=
E
t
[
1
−
α
I
i
(
r
)
]
=
E
t
−
α
E
2
t
E
0
i
(
r
)
exp
[
−
i
δ
(
r
)
]
−
α
E
2
t
E
0
i
(
r
)
exp
[
i
δ
(
r
)
]