Fig. 5

a is a situation that the numerical ratio of AOB/NOB is more than 2; b is a situation that the numerical ratio of AOB/NOB is 2; c is a situation that the numerical ratio of AOB/NOB is less than 2
a is a situation that the numerical ratio of AOB/NOB is more than 2; b is a situation that the numerical ratio of AOB/NOB is 2; c is a situation that the numerical ratio of AOB/NOB is less than 2