The mathematics of ageing:

Age is a crucial variable in social sciences and particularly in population dynamics. In this paper, we link methods from formal demography and Operations Research to investigate age-structured models to study the greying of academia. As scientific productivity is usually found to decrease at advanced ages, there was a vivid discussion on the ageing among tenured professors and faculty staff of universities. We investigate population ageing in academia from two perspectives. First, we propose a two-state optimal control model to explain the substantial variations of scientific production over the life cycle of researchers. We identify conditions under which typical hump-shaped age-specific patterns of scientific production turn out to be optimal for individual researchers. The second part of the paper deals with the dynamics of the age structure of scientific institutions. Similar to the university professors, many European learned societies experienced a rapid ageing of their member population, where they face the dilemma that keeping young, i.e. electing young entrants, has the drawback of reducing the replacement rate of members. It turns out that electing a mix of young and old members delivers the optimal solution of the problem, i.e. guaranteeing a young age structure, while ensuring a high recruitment rate

Monthly estimates of the quantum of fertility: Towards a fertility monitoring system in Austria

Short-term variations in fertility and seasonal patterns of childbearing have been of interest to demographers for a long time. Presenting our detailed study of period fertility in Austria since 1984, we discuss the problems and advantages of constructing and analysing monthly series of various period fertility indicators that reflect real exposure and potentially minimise the distortions caused by changes in fertility timing. We correct monthly birth data for calendar and seasonal factors and show that seasonality of births in Austria varies by birth order. Our study suggests that most of the timing distortions can be eliminated when using an indicator derived from the period parity progression ratios based on birth interval distributions, termed the "period average parity" (PAP). We illustrate the insights gained with the PAP and compare this with the commonly used total fertility rates in an analysis of the recent upswing in period fertility, starting in the late 2001. This investigation will be useful in establishing a monitoring of monthly fertility rates in Austria

Changing Patterns of Transition to Adulthood

While contemporary sociological and demographic studies seem to confirm the idea that the transition to adulthood is occurring at an increasingly older age in France, they have not yet clearly determined what exactly is involved in this ''passage'' from youth to adulthood. Study of schooling and educational trajectories, family and occupational paths, and analysis of the interactions between them in individual life histories, provides a fresh perspective on transitions to adulthood and the complexity thereof. Completing education, finding a job, moving out of the parental home, entering a union and founding a family\textemdashall these events are interwoven in individual life histories, and sometimes challenge the various generational and social rationales. Are we seeing convergence in the ways men and women reach adulthood? Are today's transition models characterized by greater social diversity than those of the past? This chapter presents an overall picture of the changes in the transition to adulthood that have occurred in France since the generations born in the late 1920s