Quantifying uncertainty in the biospheric carbon flux for England and Wales

Summary.  A crucial issue in the current global warming debate is the effect of vegetation and soils on carbon dioxide (CO₂) concentrations in the atmosphere. Vegetation can extract CO₂ through photosynthesis, but respiration, decay of soil organic matter and disturbance effects such as fire return it to the atmosphere. The balance of these processes is the net carbon flux. To estimate the biospheric carbon flux for England and Wales, we address the statistical problem of inference for the sum of multiple outputs from a complex deterministic computer code whose input parameters are uncertain. The code is a process model which simulates the carbon dynamics of vegetation and soils, including the amount of carbon that is stored as a result of photosynthesis and the amount that is returned to the atmosphere through respiration. The aggregation of outputs corresponding to multiple sites and types of vegetation in a region gives an estimate of the total carbon flux for that region over a period of time. Expert prior opinions are elicited for marginal uncertainty about the relevant input parameters and for correlations of inputs between sites. A Gaussian process model is used to build emulators of the multiple code outputs and Bayesian uncertainty analysis is then used to propagate uncertainty in the input parameters through to uncertainty on the aggregated output. Numerical results are presented for England and Wales in the year 2000. It is estimated that vegetation and soils in England and Wales constituted a net sink of 7.55 Mt C (1 Mt C = 10¹² g of carbon) in 2000, with standard deviation 0.56 Mt C resulting from the sources of uncertainty that are considered.     

Older disabled workers' perceptions of volunteering

The activity of volunteering is readily available to, and undertaken by, able-bodied people in Australia and is recognized as a valuable social pursuit, particularly among citizens of retirement age. Despite the known benefits of volunteering, however, there are few reports of disabled people participating as volunteers and little is understood of their experiences or perceptions of volunteering. The aim of this study was to explore how older workers within supported employment settings perceived the opportunities for and barriers to volunteering. Fourteen people with long-standing impairments participated in this small qualitative study. Overall the participants were positive about volunteering, but noted they might require support to volunteer successfully. Drawing upon the participants' views, recommendations are made for developing training. Disabled workers facing retirement need to be supported to have opportunities for active participation in the community as volunteers if so desired.     

Job Insecurity and the Timing of Parenthood: A Comparison between Eastern and Western Germany

This article contributes to the ongoing debate on the economic determinants of fertility behavior by addressing the role of job insecurity in couples’ intentions concerning parenthood and its timing. It starts from the hypothesis that cultural values moderate individuals’ reactions to job insecurity and the way it is related to family formation. With a systematic thematic content analysis of a set of semi-structured interviews with childless men and women around the age of 30 in eastern and western Germany, we are able to show that there are substantial differences in the consequences of job insecurity on intentions to have a first child. In western Germany, a relatively secure job career is expected to precede family formation, and this sequence of transitions is rather rigid, whereas in eastern Germany job security and family formation are thought of and practiced as parallel investments. We suggest that the lack of convergence in family formation patterns between eastern and western Germany after the unification of the country in 1990 is partially related to different attitudes toward job insecurity in the two contexts.     

The expressive and communicative functions of preschool children's smiles in an achievement-situation

Two studies examined how different social contexts determine whether preschoolers' smiles in an achievement-game serve an expressive function indicating success versus failure experiences and/or a communicative function. Facial behavior was coded with the Facial Action Coding System. Unexpectedly, in Study 1 children (N=19) smiled more often after failure than after success. Study 2 investigated the influence of face-to-face contact with the experimenter on preschoolers' smiles (N=20). However, there were no differences between success and failure, but with face-to-face contact subjects exhibited more smiles than without. Features of the social situation that are supposed to determine the predominance of the communicative or expressive function of a smile are discussed.We gratefully acknowledge the assistance of Detlef Friedrich and Katja Johann in the data collection and Signe Preuschoft in coding and analyzing the data.     

Economics of Radiation Protection: Equity Considerations

In order to implement cost-benefit analysis of protective actions to reduce radiological exposures, one needs to attribute a monetary value to the avoided exposure. Recently, the International Commission on Radiological Protection has stressed the need to take into consideration not only the collective exposure to ionising radiation but also its dispersion in the population. In this paper, by using some well known and some recent results in the economics of uncertainty, we discuss how to integrate these recommendations in the valuation of the benefit of protection.