Origin and evolution of the light nuclides

After a short historical (and highly subjective) introduction to the field, I discuss our current understanding of the origin and evolution of the light nuclides D, He-3, He-4, Li-6, Li-7, Be-9, B-10 and B-11. Despite considerable observational and theoretical progress, important uncertainties still persist for each and every one of those nuclides. The present-day abundance of D in the local interstellar medium is currently uncertain, making it difficult to infer the recent chemical evolution of the solar neighborhood. To account for the observed quasi-constancy of He-3 abundance from the Big Bang to our days, the stellar production of that nuclide must be negligible; however, the scarce observations of its abundance in planetary nebulae seem to contradict this idea. The observed Be and B evolution as primaries suggests that the source composition of cosmic rays has remained quasi-constant since the early days of the Galaxy, a suggestion with far reaching implications for the origin of cosmic rays; however, the main idea proposed to account for that constancy, namely that superbubbles are at the source of cosmic rays, encounters some serious difficulties. The best explanation for the mismatch between primordial Li and the observed "Spite-plateau" in halo stars appears to be depletion of Li in stellar envelopes, by some yet poorly understood mechanism. But this explanation impacts on the level of the recently discovered early ``Li-6 plateau'', which (if confirmed), seriously challenges current ideas of cosmic ray nucleosynthesis.Comment: 18 pages, 9 figs. Invited Review in "Symposium on the Composition of Matter", honoring Johannes Geiss on the occasion of his 80th birthday (Grindelwald, Switzerland, Sept. 2006), to be published in Space Science Series of ISS

Student Success at the University of Pretoria, 2009-2019: A Systemic, Intentional and Data-Informed Strategy

Preface: In essence, the publication provides an exposé of the evolution of an increasingly complex and comprehensive student success strategy developed by a South African university (viz the University of Pretoria). The problem facing the University in 2009 was common across the higher education sector in South Africa: the phenomenon of student success. This publication is a case study or series of case studies of how the University of Pretoria intentionally integrated its student support and development programmes between 2009 and 2019, and how it innovated and improved the holistic programme over the decade. The outcome was a gradual increase in the student success rate as measured by both module pass percentage (defined as the number of students who passed v the number who enrolled for the module) and minimum time to completion of individual cohorts (‘cohort’ defined as a group of first-time entering students followed through to graduation). The chapter reflects on contextualised approaches to student success initiatives that are similar to those found at other institutions, nationally and internationally. Using case studies shows how initiatives develop over time within a unique context, as well as challenges and successes. This publication has both a descriptive and exploratory approach in its case studies. Existing but siloed initiatives within the University were uncovered, interrogated, improved and integrated into a broader programme between 2009 and 2019. The cases might provide some insights into the phenomenon of student success that other South African institutions could contextualise

Weber and church governance: religious practice and economic activity

The debate about the relationship between religion and economic activity in the wake of Weber has been cast largely in terms of belief and values. This article suggests an alternative focus on practice. It argues that taken for granted practices of church governance formed to-hand resources for the organization of economic activity. The argument is developed through an examination of the historical development of church governance practices in the Presbyterian Church of Scotland, with particular emphasis on the way in which theological belief gave rise to practices of accountability and record keeping. In turn such practices contributed to a ‘culture of organization’ which had implications for economic activity. A focus on governance practices can help to illuminate enduring patterns of difference in the organization of economic activity