The Hes1 equations model the oscillatory cycles of protein and messenger ribonucleic acid (mRNA) levels in cultured cells. The system components \(X = (P, M, H)\) represent the concentrations of protein, mRNA, and the Hes1-interacting factor that provides a negative feedback loop.
\(P\), \(M\), and \(H\) are governed by the following differential equations:
$$ \frac{dP}{dt} = -aPH + bM - cP $$
$$ \frac{dM}{dt} = -d_M M + \frac{e}{1 + P^2} $$
$$ \frac{dH}{dt} = -aPH + \frac{f}{1+ P^2} - gH $$
where \(\theta = (a,b,c,d_M,e,f,g)\) are system parameters.