Aspetti nazionali ed internazionali delle popolazioni considerate da una "finestra demografica"

A first aim of this paper is to examine the demographic machinery of the first and second demographic transition and to try to evaluate when and how long a "demographic window" - recognized trough the "dependency ratio" - is opened in a population. A second aim is an attempt to evaluate the possible impact of spatial differences in timing and length of demographic windows on relations, both economic and migratory ones, among countries. In brief, we want to give "a domestic and an international view on population from a demographic window". In order to evaluate the whole process and possible costs and benefits of the first and second demographic transition, we preferred to make reference to actual populations rather than to theoretical ones, in particular to four countries placed along the road from the beginning of the first demographic transition to the heart of the second one: Nigeria, Egypt, China, and Italy.