Global attractivity of periodic solution in a model of hematopoiesis

Sufficient conditions are obtained for the global attractivity of a positive periodic solution for the periodic equation dP(t)/dt = -delta(t)P(t) - beta(t)P(t)/1+P-n(t) + alpha(t) integral(0)(infinity) K(s) P(t-s)/1+P-n(t-s) ds, for n > 0, where delta(t), beta(t), alpha(t) are continuous positive periodic function on [0,infinity) with a period omega > 0 and K(s) is a delay kernel. (C) 2002 Elsevier Science Ltd. All rights reserved.