On global dynamics in a periodic differential equation with deviating argument

Several aspects of global dynamics and the existence of periodic solutions are studied for the scalar differential delay equation x′(t)=a(t)f(x([t-K]))x′(t)=a(t)f(x([t-K])), where f(x)f(x) is a continuous negative feedback function, x·f(x)<0,x≠0,0