Internal quantum efficiency and tunable colour temperature in monolithic white InGaN/GaN LED

Internal Quantum Efficiency (IQE) of two-colour monolithic white light emitting diode (LED) was measured by temperature dependant electro-luminescence (TDEL) and analysed with modified rate equation based on ABC model. External, internal and injection efficiencies of blue and green quantum wells were analysed separately. Monolithic white LED contained one green InGaN QW and two blue QWs being separated by GaN barrier. This paper reports also the tunable behaviour of correlated colour temperature (CCT) in pulsed operation mode and effect of self-heating on device performance. © 2014 SPIE.

White football in South Africa: empire, apartheid and change, 1892-1977

This essay traces the development, domination and decline of white football in South Africa. It suggests that white football was more significant and popular than generally acknowledged and was at the forefront of globalizing football in the early twentieth century. In order to better understand the broader history of twentieth-century South African football, a more detailed examination of the organized white game at the national and international levels is necessary. This historical analysis of elite white football draws from the archives of the Football Association of South Africa. The analysis underscores the important role of white football authorities in the contestation of power and identity in the game in South Africa and abroad. In the first period under consideration (1892-1940s), local football authorities challenged the dominant sports within South Africa. This period was followed in the 1950s by the challenges of professionalism and anti-apartheid organizations. In the final phase (1967-77), officials experimented with football on 'multi-national' and multi-racial lines - a failed reform that led to the demise of white football.