β

h ( t , 0 )

h t ( t , 0 )

< β < 1

h ( t , 0 ) 0

t

h t ( t , 0 ) < 0

β = 1

h ( t , 0 ) = h ( 0 , 0 )

0 t

h t ( t , 0 ) = 0

1 < β < 5 3

h ( t , 0 )

t

h t ( t , 0 ) > 0

β = 5 3

h ( t , 0 )

t

Exponentially

h t ( t , 0 ) > 0

5 3 < β 2

h ( t , 0 )

t t 1

h t ( t , 0 ) > 0