REM sleep deprivation during 5 hours leads to an immediate REM sleep rebound and to suppression of non-REM sleep intensity

Nine healthy male subjects were deprived of REM sleep during the first 5 h after sleep onset. Afterwards recovery sleep was undisturbed. During the deprivation period the non-REM EEG power spectrum was reduced when compared to baseline for the frequencies up to 7 Hz, despite the fact that non-REM sleep was not experimentally disturbed. During the recovery interval a significant rebound of REM sleep was observed, which was only accompanied by a very slight increase of power in the lower non-REM EEG frequencies. In order to control for intermittent wakefulness, the same subjects were subjected to non-REM sleep interruption during the first 5 h after sleep onset 2 weeks later. Again subsequent recovery sleep was undisturbed. The interventions resulted in a similar amount of wakefulness in both conditions. During the intervention period, the non-REM EEG power spectrum was only marginally reduced in the delta frequency range. REM sleep duration was only slightly reduced. During the recovery interval, however, a substantial increase in EEG power in the delta frequency range was noted, without notable changes in REM time. It is concluded that an increased pressure for REM sleep results in longer REM episodes and a reduced intensity of non-REM sleep.

Simple bounds for queueing systems with breakdowns

Computationally attractive and intuitively obvious simple bounds are proposed for finite service systems which are subject to random breakdowns. The services are assumed to be exponential. The up and down periods are allowed to be generally distributed. The bounds are based on product-form modifications and depend only on means. A formal proof is presented. This proof is of interest in itself. Numerical support indicates a potential usefulness for quick engineering and performance evaluation purposes

South African manufacturing performance in international perspective, 1970-1999

This paper analyses the historical performance of the South African manufacturing sector in an international perspective. After a brief overview of the industrialisation process of South Africa during the 20th century, a binary comparison of manufacturing output and productivity between South Africa and the US is presented. The industry-of-origin approach is used to construct unit value ratios (UVRs), as an alternative to the exchange range for converting US and South African output data into the same currency. Subsequently, the UVRs are used to estimate labour and total factor productivity levels for total manufacturing and 13 manufacturing branches for the period 1970-1999 in comparison to the USA. Next, these results are used to compute relative unit labour costs, which shed light on the international competitiveness of the South African manufacturing sector at a detailed level. The study is part of the International Comparisons of output and Productivity (ICOP) project carried out at the universities of Groningen and Eindhoven. We find that there exists a considerable labour and total productivity gap between the US and South Africa, which is continuously widening over time. In 1970, labour productivity stood at 32 percent of US level, while it was only 20 percent in 1999. With respect to relative unit labour costs, the results show that on average, South Africa is competitive with the USA, albeit there are some industries which show consistent relative unit labour costs above US level.

A microprocessor based, multi-channel low-temperature monitoring system

A multi-channel low-temperature monitoring system and its design considerations are presented. The system is microprocessor based and specially designed to interface thermoresistive sensors in cryogenic experiments. The system can be easily expanded to accept any type of physical transducer and to perform other output functions, ie control functions

Food for talk: photo frames to support social connectedness for elderly people in a nursing home

Social connectedness is crucial to someone’s well-being. A case study is conducted to test whether the social connectedness of elderly people living in a nursing home and their family and friends can be improved through a photo frame. A SIM-based photo frame is used to keep the elderly people informed about the comings and goings of their loved ones. Eight elderly people living in a nursing home participated in this case study for 6-7 weeks. A content analysis of the photos revealed that the photos often were related to special events or holidays that happened in the past. Interviews indicated that the photos mainly served as food for talk, i.e. the photos initiated conversations between the elderly people mutually, with their family members and with the healthcare professionals. They all liked the photo frame and it didn’t serve as a means to exchange news, but as a catalyst to talk –mainly- about the past