Eureka and beyond: mining's impact on African urbanisation

This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-states’ urbanisation trends have shown considerable variation over the past half century. The current surge in ‘new’ mining countries and the slow-down in ‘old’ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)

Cashew Nut Production in Tanzania: Constraints and Progress through Integrated Crop Management.

Cashew (Anacardium occidentale L.) is the fourth most valuable Tanzanian export crop after coffee, cotton and tea. Following a steady increase in production from the middle of this century, there was a dramatic decline from 145,000 t in 1973 to 16,500 t in 1986. This was caused by a complex of socio-economic (low producer prices, inefficient marketing, villagisation) and biological factors (cashew powdery mildew disease, low tree yields, overcrowding of trees). Recently, higher cashew prices and liberalised marketing have created favourable conditions that have encouraged farmers to tackle several of the biological constraints on production. As a result, cashew production has risen steadily from 16,500 t in 1986 to 70,320 t in 1994

Vibrio harveyi: a significant pathogen of marine vertebrates and invertebrates

Vibrio harveyi, which now includes Vibrio carchariae as a junior synonym, is a serious pathogen of marine fish and invertebrates, particularly penaeid shrimp. In fish, the diseases include vasculitis, gastro-enteritis and eye lesions. With shrimp, the pathogen is associated with luminous vibriosis and Bolitas negricans. Yet, the pathogenicity mechanisms are imprecisely understood, with likely mechanisms involving the ability to attach and form biofilms, quorum sensing, various extracellular products including proteases and haemolysins, lipopolysaccharide, and interaction with bacteriophage and bacteriocin-like substances