Periodicity in a logistic type system with several delays

With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, easily verifiable criteria are established for the global existence of positive periodic solutions of the following several delays logistic type system: du(t)dt=u(t)[a(t)-@?j=1mb"j(t)(u(t-@t"j(t)))^@q^"^j], where a(t), b"j(t) are positive periodic continuous functions with periodic @w > 0, @t"j (t) are nonnegative continuous periodic functions with periodic @w > 0. After that, by constructing a suitable Lyapunov functional, some sufficient conditions which guarantee the stability of the positive periodic solutions are obtained..