Let \( \alpha_{\theta} \) and \( \beta_{\theta} \) be the distinct roots of \( 2x^{2}+(\cos \theta)x-1=0 , \; \theta \in (0,2\pi) \). If \( m \) and \( M \) are the minimum and the maximum values of \( \alpha_{\theta}^{4}+\beta_{\theta}^{4} \), then \( 16{(M+m)} \) equals:
