background: pulmonary function tests (pfts) are used in assessing physiological to clinical status of the respiratory system, which is expressed as a percentage of predicted values. predicted pfts values are varies in different ethnics. predicted pfts values were studied in a sample of iranian children. materials and methods: prediction equations for pfts were derived from urban children in the...

in this paper, sufficient conditions are investigated for the existence of periodic (not necessarily positive) solutions for nonlinear several time delay population system with feedback control. nonlinear system affected by an periodic external source is studied. existence of a control variable provides  the extension of  some previous results obtained in other studies. we give a illustrative e...

A development quadratic model of the heterogeneous biological population consisting of a few sub-populations is investigated. The classic stabilization problem of solutions for the system of ordinary quadratic differential equations, which describing this model, is solved. Examples are given. 2013 Elsevier Inc. All rights reserved.

For the standard one sector stochastic optimal growth model, we outline a new set of conditions for a policy function that satisfies the Ramsey-Euler equation to be optimal. An interior Ramsey-Euler policy function is optimal if (and only if) it is continuous or alternatively, if both consumption and investment are non-decreasing in output. One does not need to verify the transversality conditi...

The diversity of life is a fundamental empirical fact of nature. Casual observation alone confirms the great variety of species. But diversity also prevails within single species. As in human populations, the individuals of a species vary considerably in their outward traits—size and shape, external markings, fecundity, disease resistance, etc. This is called phenotypic variation, and, since ph...