Inferring transient dynamics of human populations from matrix non-normality

This is the final version of the article. Available from Springer Verlag via the DOI in this record.In our increasingly unstable and unpredictable world, population dynamics rarely settle uniformly to long-term behaviour. However, projecting period-by-period through the preceding fluctuations is more data-intensive and analytically involved than evaluating at equilibrium. To efficiently model populations and best inform policy, we require pragmatic suggestions as to when it is necessary to incorporate short-term transient dynamics and their effect on eventual projected population size. To estimate this need for matrix population modelling, we adopt a linear algebraic quantity known as non-normality. Matrix non-normality is distinct from normality in the Gaussian sense, and indicates the amplificatory potential of the population projection matrix given a particular population vector. In this paper, we compare and contrast three well-regarded metrics of non-normality, which were calculated for over 1000 age-structured human population projection matrices from 42 European countries in the period 1960 to 2014. Non-normality increased over time, mirroring the indices of transient dynamics that peaked around the millennium. By standardising the matrices to focus on transient dynamics and not changes in the asymptotic growth rate, we show that the damping ratio is an uninformative predictor of whether a population is prone to transient booms or busts in its size. These analyses suggest that population ecology approaches to inferring transient dynamics have too often relied on suboptimal analytical tools focussed on an initial population vector rather than the capacity of the life cycle to amplify or dampen transient fluctuations. Finally, we introduce the engineering technique of pseudospectra analysis to population ecology, which, like matrix non-normality, provides a more complete description of the transient fluctuations than the damping ratio. Pseudospectra analysis could further support non-normality assessment to enable a greater understanding of when we might expect transient phases to impact eventual population dynamics.This work was funded by Wellcome Trust New Investigator 103780 to TE, who is also funded by NERC Fellowship NE/J018163/1. JB gratefully acknowledges the ESRC Centre for Population Change ES/K007394/1

Male Responsibility in Reproductive Health in Nigeria: An Eclectic Methodological Approach

An eclectic methodological approach to the study of men within the framework of reproductive health and related issues was experimented in this study. Literary discourse has focused on the study of male involvement in reproduction from the narrow perspective of what more men need to do to increase women\'s acceptance of contraception and utilization of relevant services. But few studies employed a diffuse approach to providing answers to the seemingly intractable issue of maleness as it impacts the whole gamut of reproductive health issues and human development. The present research derived from a growing recognition of situating male behavior within the socio-cultural context using ethnomethodology as an invaluable method of analyzing maleness from the evolutionary construct. Analysis of literary criticism and evaluation of discourse relevant to the evolutionary pattern of gender construction, manhood, masculinity, sexuality, family and social relationship were adopted using anthropological and sociological methods. The advantage of this process is the use of eclectic and iterative approaches of articulating the evolutionary trend of manhood and gender, their implications for sexuality culminating in family and other stable relationships. The potential benefits and limitations of the research design are discussed. The study proposes the use of more diffuse approaches in the study of male involvement in reproduction and human development. African Journal for the Psychological Study of Social Issues Vol.7(2) 2004: 167-19