
 Increase of  

 $a,d$  $N$ 
The case of the synchronized region unbounded  ${\lambda}_{2}\approx \frac{4a{\pi}^{2}}{{N}^{2}}$  ↑  ↓ 
The case of the synchronized region bounded  $R\approx \frac{{N}^{2}}{{\pi}^{2}}$  —  ↓ 