Lentiviral manipulation of gene expression in human adult and embryonic stem cells

Human stem cells could revolutionize the field of medicine by providing a diverse range of cell types for tissue replacement therapies and drug discovery. To achieve this goal, genetic tools need to be optimized and developed for controlling and manipulating stem cells ex vivo. Here we describe a lentiviral delivery system capable of high infection rates in human mesenchymal and embryonic stem cells. The lentiviral backbone was modified to express mono- and bi-cistronic transgenes and was also used to deliver short hairpin ribonucleic acid for specific silencing of gene expression in human stem cells. We show that lentiviral transduction can be used to alter gene expression without altering the genes' ability to differentiate in vitro. These vectors will enable rapid analysis of gene function in stem cells and permit the generation of knock-in / knock-out models of human disease in the rapidly developing field of gene therapy

The Disaster Management Act 57 of 2002: part panacea or ready recipe for disaster?

Floods, earthquakes, landslides, volcanic eruptions, explosions, runaway fires, and transportation and other accidents are all occurrences with which we are familiar, if only vicariously. These events can presumably all be categorised as ‘disasters’. But can the same be said for the dumping of hazardous waste, ships running aground, farm invasions and large-scale evictions, major traffic accidents and the issue of cross-border or internal refugees? When is an event considered a ‘disaster’, who determines that an event is a ‘disaster’, who can do what to prepare for the ‘disaster‘ and what can be done to alleviate the effects of the disaster after it has happened

Pax Romana as background of the Christian kerygma

The concept ‘kingdom of God’ is fundamental to the kerygma on the salvific meaning of Jesus Christ in New Testament times. This article aims to explore the raison d’être why this concept had been such an important element in the kerygma. It argues that the Pax Romana as the primary ideology of the Roman Empire played a significant role. The Pax Romana advocated harmony with the gods, and subsequent heavenly peace and global stability and security in the inhabited world. However, the kerygma replaced the Pax Romana as an ideology with the apocalyptic-eschatological concept ‘kingdom of God’. According to apocalyptic eschatology, an end to the known world is expected. This end was considered to be a cataclysmic catastrophe awaiting in the future, albeit indeterminate to humankind. On the contrary, the church’s kerygma proclaimed that the kingdom of God was already present. An element of Jewish apocalyptism, however, remained in the Christian religion - yet adjusted. That is, although the kingdom of God was regarded already present, the idea of a second coming of Christ as Redeemer was upheld. The article demonstrates that the Christian kerygma on the realised kingdom of God had its origins in the expectation of an utopia, as envisaged in the Pax Romana as ideology.http://www.hts.org.zaam201

Axial flow fan performance in a forced draught air-cooled heat exchanger for a sCO2 Brayton cycle

An axial flow cooling fan has been designed for use in a concentrated solar power plant. The plant is based on a supercritical carbon dioxide (sCO2) Brayton cycle, and uses a forced draft air-cooled heat exchanger (ACHE) for cooling. The fan performance has been investigated using both computational fluid dynamics (CFD) and scaled fan tests. This paper presents a CFD model that integrates the fan with the heat exchanger. The objective is to establish a foundation for similar models and to contribute to the development of efficient ACHE units designed for sCO2 power cycles. The finned-tube bundle is simplified, with a Porous Media Model representing the pressure drop through the bundle. Pressure inlet and -outlet boundary conditions are used, meaning the air flow rate is solved based on the fan and tube bundle interaction. The flow rate predicted by the CFD model is 0.5% higher than the analytical prediction, and 3.6% lower than the design value, demonstrating that the assumptions used in the design procedure are reasonable. The plenum height is also found to affect the flow rate, with shorter plenums resulting in higher flow rates and fan efficiencies, and longer plenums resulting in more uniform cooling air flow

Observations of the habitats and biodiversity of the submarine canyons at Sodwana Bay

The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them

A continuous process for the biological treatment of heavy metal contaminated acid mine water

Alkaline precipitation of heavy metals from acidic water streams is a popular and long standing treatment process. While this process is efficient it requires the continuous addition of an alkaline material, such as lime. In the long term or when treating large volumes of effluent this process becomes expensive, with costs in the mining sector routinely exceeding millions of rands annually. The process described below utilises alkalinity generated by the alga Spirulina sp., in a continuous system to precipitate heavy metals. The design of the system separates the algal component from the metal containing stream to overcome metal toxicity. The primary treatment process consistently removed over 99% of the iron (98.9 mg/l) and between 80 and 95% of the zinc (7.16 mg/l) and lead (2.35 mg/l) over a 14-day period (20 l effluent treated). In addition the pH of the raw effluent was increased from 1.8 to over 7 in the post-treatment stream. Secondary treatment and polishing steps depend on the nature of the effluent treated. In the case of the high sulphate effluent the treated stream was passed into an anaerobic digester at a rate of 4 l/day. The combination of the primary and secondary treatments effected a removal of over 95% of all metals tested for as well as a 90% reduction in the sulphate load. The running cost of such a process would be low as the salinity and nutrient requirements for the algal culture could be provided by using tannery effluent or a combination of saline water and sewage. This would have the additional benefit of treating either a tannery or sewage effluent as part of an integrated process