AIDS in Africa: a perspective on the epidemic

Issues surrounding the spread of acquired immunodeficiency syndrome (AIDS) in Africa are summarized. Subjects considered include the disease's origins, proportion of the population infected with the human immunodeficiency virus (HIV) and AIDS, the problems in caring for children orphaned by the disease, innovations in drug treatments discovered by African scientists, the spread among women, and the difficulties inherent in incorporating Western-based policy and aid provisions into the African context.     

Multiphase flow simulation through porous media with explicitly resolved fractures

Accurate simulation of multiphase flow in fractured porous media remains a challenge. An important problem is the representation of the discontinuous or near discontinuous behaviour of saturation in real geological formations. In the classical continuum approach, a refined mesh is required at the interface between fracture and porous media to capture the steep gradients in saturation and saturation‐dependent transport properties. This dramatically increases the computational load when large numbers of fractures are present in the numerical model. A discontinuous finite element method is reported here to model flow in fractured porous media. The governing multiphase porous media flow equations are solved in the adaptive mesh computational fluid dynamics code IC‐FERST on unstructured meshes. The method is based on a mixed control volume – discontinuous finite element formulation. This is combined with the P_N+1DG‐P_NDG element pair, which has discontinuous (order N+1) representation for velocity and discontinuous (order N) representation for pressure. A number of test cases are used to evaluate the method's ability to model fracture flow. The first is used to verify the performance of the element pair on structured and unstructured meshes of different resolution. Multiphase flow is then modelled in a range of idealised and simple fracture patterns. Solutions with sharp saturation fronts and computational economy in terms of mesh size are illustrated.     

Die departement geskiedenis/The history department

Abstract

This article traces changing interpretations of the nature of Coloured identity and the history of the Coloured community in South Africa in both popular thinking as well as the academy. It explores some of the main contestations that have arisen between rival schools of thought, particularly their stance on the popular perception that Colouredness is an inherent racial condition derived from miscegenation. This essay identifies four distinct paradigms in historical writing on the Coloured people. Firstly, there is the essentialist school which regards Colouredness as a product of miscegenation and represents the conventional understanding of the identity. Secondly, instrumentalists view Coloured identity as an artificial creation of the white ruling class who used it as a ploy to divide and rule the black majority. This explanation, which first emerged in academic writing in the early 1980s, held sway in anti-apartheid circles. Opposing these interpretations are what may be termed the social constructionists who from the early 1990s stressed the complexities of identity formation and the agency of Coloured people in the making of their own identities. Most recently the rudiments of a fourth approach, of applying postmodern theory, especially the concept of creolisation, to Coloured identity have appeared.     

Commuter lives: a review symposium on David Bissell's Transit Life

This article presents a series of commentaries on Transit Life: How Commuting is Transforming Our Cities, published by MIT Press in 2018. Centring on an in—depth case study of Sydney, the book argues the need to attend carefully to the fine—grained detail of the commuting experience. In all sorts of ways, Transit Life presents a way of thinking about urban transportation radically different from that used by mainstream transport planners and geographers. Geographical Research asked six researchers—Tim Edensor, Michele Lobo, Debbie Hopkins, Helen Fitt, Juliana Mansvelt, and Donald McNeill—to reflect on what kind of research vistas might be opened up bring the tools of cultural geography and mobility research to the world of commuting. Here are their responses, rounded out by a reply by David Bissell, Transit Life's author.