dx1/dt = lm - x1*d - x1*x3*beta;
dx2/dt = x1*x3*beta - a*x2;
dx3/dt = k*x2 - x3*u;
dx4/dt = -b*x4 + c*x4*x1*x2 - c*x4*q*x2;
dx5/dt = c*x4*q*x2 - h*x5;
y1 = x4;
y2 = x5
