Race‐gender variations in the demographic characteristics of doctoral scientists

Most of the research literature has given little or no attention to the social backgrounds and traits of black scientists and female scientists. The present study, based on survey findings on a national sample of American scientists, helps to fill this gap. Female scientists are compared with their male colleagues, and black scientists with their white colleagues. Race is a better predictor than gender of certain demographic characteristics. However, a clearer picture of variations in social background and current family patterns is derived from an analysis which controls for both race and gender. This analysis includes data on social status of parents, marital status of scientist, number of siblings and number of offspring, religious identity, and region of origin. The implications of these survey findings for the future development of scientific talent are explored, including some implications for researchers, sociologists of science, and social planners.     

Assessing the Potential Impact of the HIV-1 Epidemic on Orphanhood and the Demographic Structure of Populations in sub-Saharan Africa

Much of the debate on the demographic consequences of the HIV epidemic in sub-Saharan Africa has so far centred around the plausibility of population declines in areas where unprecendently high rates of population growth have recently been in evidence. In this article, the authors use a mathematical model, which combines epidemiological and demographic processes, to illustrate how, under a broad range of impacts on population growth, major changes in demographic features, such as the extent of orphanhood within populations, are likely to occur. At the same time, HIV epidemics are liable to cause significant shifts in the age and sex composition of affected populations, which may have important implications for the ways in which they are best able to cope with the increases in orphanhood, as well as those in infant, early childhood and adult mortality.     

Finite mixtures of multivariate skew t-distributions: some recent and new results

Finite mixtures of multivariate skew t (MST) distributions have proven to be useful in modelling heterogeneous data with asymmetric and heavy tail behaviour. Recently, they have been exploited as an effective tool for modelling flow cytometric data. A number of algorithms for the computation of the maximum likelihood (ML) estimates for the model parameters of mixtures of MST distributions have been put forward in recent years. These implementations use various characterizations of the MST distribution, which are similar but not identical. While exact implementation of the expectation-maximization (EM) algorithm can be achieved for ‘restricted’ characterizations of the component skew t-distributions, Monte Carlo (MC) methods have been used to fit the ‘unrestricted’ models. In this paper, we review several recent fitting algorithms for finite mixtures of multivariate skew t-distributions, at the same time clarifying some of the connections between the various existing proposals. In particular, recent results have shown that the EM algorithm can be implemented exactly for faster computation of ML estimates for mixtures with unrestricted MST components. The gain in computational time is effected by noting that the semi-infinite integrals on the E-step of the EM algorithm can be put in the form of moments of the truncated multivariate non-central t-distribution, similar to the restricted case, which subsequently can be expressed in terms of the non-truncated form of the central t-distribution function for which fast algorithms are available. We present comparisons to illustrate the relative performance of the restricted and unrestricted models, and demonstrate the usefulness of the recently proposed methodology for the unrestricted MST mixture, by some applications to three real datasets.     

Age discrimination and working life: Perspectives and contestations – a review of the contemporary literature

This review highlights some of the principal issues and debates surrounding age discrimination at the workplace. Essentially, the existing research in this area can be divided into three broad, although somewhat overlapping, categories. The first explores the underlying causes and consequences of age discrimination at the workplace from one or other theoretical tradition. The second broad body of literature encompasses empirical studies which document the nature and extent of age discrimination, based on the use of official statistics, and/or firm‐level survey evidence. The third explores the effects of various governmental initiatives to reduce the incidence of age discrimination and policy options in this area. Even though age discrimination is widely accepted to be prevalent, its causes are rather more contentious. Age discrimination has variously been ascribed to market imperfections, the product of rational choices and the effects of long‐term changes in the nature of the economy. Policy interventions may be prompted by economic pressure, demographic changes or cultural shifts, and have involved voluntary codes as well as legislation. Although voluntary codes have generally proved ineffective, the literature indicates that more formal regulations may still have only limited efficacy, underscoring the deeply rooted nature of age discrimination in society.     

The Siable-Law Model of Stock Returns

This study investigates the tail shapes of empirical distributions of returns on an extensive group of common stocks. The tails of the return distributions are found to be thinner than those of infinite variance stable distributions. Therefore, although homogeneity is evident in general, economic and statistical inferences drawn from stable-law parameters estimated from samples of stock returns may be misleading. This is in spite of the apparent overall similarity (in shape) between empirical and stable distributions.     

Reputational Capital and Academic Pay

This article examines how research productivity, administrative service, and teaching affect reputational capital in the market for academic economists. Also, we investigate the issue of the durability of reputational capital, estimating the penalties associated with gaps in research output. Our results reveal that (1) the market makes a distinction between the quantity and the quality of an individual's research output, (2) a smaller number of frequently cited papers enhances reputational capital more than a greater number of less frequently cited papers, (3) reputational capital does not depreciate rapidly during research breaks, and (4) the market does not discount co-authored papers.     

Young Mother (in the) Hood: Gang Girls' Negotiation of New Identities

This article examines the experiences of young women in street gangs who become mothers. Drawing on qualitative interviews with 65 young women in the San Francisco, CA, Bay Area, we examine their narratives about the transition to motherhood. In particular, we focus on the ways these young women negotiate femininities and attempt to reconcile their identities as young mothers and gang girls-both stigmatized identities. For many of the young women, motherhood entails a retreat from the street and a renewed emphasis on time spent in the home. While many receive (financial and childcare) support from their families, this also often means a diminution of the autonomy they experienced while more heavily involved in the gang. Issues of respect and respectability remain important for the young women, but the dimensions on which these are based change.     

Legacy,Policy, and Circumstance in Fertility Transition

Divergent fertility trends in the course of development are commonly ascribed to differences in state action—that is, to government policy, deliberate or inadvertent. However, fertility outcomes can also, often more persuasively, be traced to differences in cultural and institutional inheritance and in the supply and growth potential of human capital. These are materials that states and societies find themselves endowed with—in brief, their legacy. In reality, legacy and policy are interwoven: policy actions build on some legacy elements and attempt to combat others. And there is a third set of factors influencing fertility outcomes, covering distinctive features of the economic and geopolitical environment and essentially fortuitous events—together termed circumstance. Legacy and circumstance can shrink or shift the policy space, helping to explain past failures in policy achievement. These broad considerations are the basis for a sketch of East Asian/sub‐Saharan African contrasts in fertility transition over the last 50 years. The sketch points to missing avenues of policy action in the African case in seeking to overcome legacy obstacles.