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.

African Regional Integration: Implications for Food Security

This report looks at the African regional trade, regional integration agreements (RIAs) and the implications for food security. An overview is presented on the present state of African regional integration and the determinants of regional trade in agriculture and food commodities. In particular the study focuses on eight target countries, related RIAs and a set of strategic food commodities. The evidence presented in this study shows that African countries have made progress in opening up agriculture and food trade with partner countries. With, the exception of Ghana, Tanzania and Mozambique, the effective applied tariff rates for regional trade partners are substantially lower than the (MFN) rates applied to world trade partners. Nonetheless, regional trade in agriculture and food only increased marginally between 1990 and 2009, and is relatively low in comparison with other developing regions. The weak state of soft and hard infrastructure, rather than high trade tariffs, seem to be the cause of thi

Outline of a multilevel approach of the network society

Social and media networks, the Internet in particular, increasingly link interpersonal, organizational and mass communication. It is argued that this gives a cause for an interdisciplinary and multilevel approach of the network society. This will have to link traditional micro- and meso-level research of social and communication ties (Rogers, Granovetter a.o.) to the macro-level research of the network society at large (Castells a.o.).\ud Systems theory linked to a theory of communicative action establishes a potential basis for a multilevel theory. The systems theory described uses elements of a biologically inspired analysis of networks as complex adaptive systems and the mathematically inspired theory of random and scale-free networks recently elaborated by Barabási, Strogatz and Watts. The outline of the multilevel theory is summarized in ten statements about changing relationships in the network society: an information society with structures and modes of organization primarily shaped by social and media networks. \ud In the last section an inventory is made of the theoretical and methodological changes communication science will have to make to develop a general theory of the information and the network society in the perspective of communication

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

Simple and insensitive bounds for a grading and an overflow model

Simple and intuitively obvious lower and upper bounds are suggested for a specific grading and an overflow model. The bounds are based on product-type modifications and are insensitive. Numerical support indicates a potential usefulness for quick engineering purposes