For the curve $C:\left(x^{2}+y^{2}-3\right)+\left(x^{2}-y^{2}-1\right)^{5}=0$, the value of $3 y^{\prime}-y^{3} y^{\prime \prime}$, at the point $(\alpha, \alpha)$, $\alpha>0$, on C, is equal to ____________.