Improved timing recovery in wireless mobile receivers

The problem of timing recovery in wireless mobile receiver systems is critical. This is partly because timing recovery functions must follow rapid parameter changes inherent in mobile systems and partly because both bandwidth and power must be conserved in low signal to noise ratio communication channels. The ultimate goal is therefore to achieve a low bit error rate on the recovered information for improving QoS provisioning to terminal mobile users. Traditional timing recovery methods have over-relied on phase-locked loops for timing information adjustment. However, associated schemes do not exploit code properties. This leads to synchronization difficulties in digital receivers separated from transmitters by lossy channels. In this paper we present a soft timing phase estimation algorithm for wireless mobile receivers in low signal to noise ratios. In order to develop a bandwidth and power efficient timing recovery method for wireless mobile receivers, a raised cosine filter and a multilevel phase shift keying modulation scheme are implemented and no clock signals are transmitted to the receiver. In the proposed method, the receiver exploits the soft decisions computed at each turbo decoding iteration to provide reliable estimates of a soft timing signal, which in turn, improves the decoding time. The derived method, based on sequential minimization techniques, approaches the theoretical Cramer-Rao bound with unbiased estimates within a few iterations.Key Words: discrete polyphase matched filters, maximum likelihood estimators, iterative turbo receivers, log-MAP b

Teacher burnout: Construct equivalence and the role of union membership

The objective in this study was to investigate its structure and validate the Maslach Burnout Inventory for educators in the Goldfields region of the northern Free State province of South Africa. A cross-sectional survey design was used, where a sample of educators was drawn from the total population (N=468). An adapted version of the Maslach Burnout Inventory and a biographical questionnaire were administered. Exploratory factor analysis with target rotations confirmed construct equivalence of burnout dimensions for an Afrikaans and English subgroup and an African Languages subgroup. Burnout is described as consisting of exhaustion, cynicism, depersonalisation, and professional efficacy. However, the depersonalisation construct showed better fit across language groups than the cynicism construct. Item bias analysis was carried out for the cynicism items. For biographical differences, it was found that union membership presented an important distinction in educators ' experience of burn out.South African Journal of Education Vol. 26 (4) 2006: pp. 541-55

Pandemic governance: Developing a politics of informality.

South Africa had the privilege of learning from how other countries responded to the crisis engendered by the COVID-19 pandemic. However, this opportunity seems to have been lost as the South African government made the mistake of transposing a developed-world preventive response onto a largely developing-world populace. The government failed to map out how factors such as South Africa’s demographic composition, spatial architecture, the incidence of poverty and informality, and competing epidemics would interact synergistically and shape epidemiological outcomes. In this article shaped by sociological insights, we show how the application of governance systems can give rise to many unintended social consequences when the knowledge forms upon which they are based are not suitably tailored to meet the needs of the specific local context. We highlight how informality can play a valuable role in fighting the COVID crisis and suggest that, to truly succeed, the government should include rather than override informal principles of governance.Significance:We present a brief comparative analysis of the responses of different nation states to the COVID-19 pandemic. The insights contribute to the sociological literature as well as to other disciplines, highlighting how local contextual factors are (re)shaping the form of policy responses as well as their associated consequences. More specifically, we focus on the importance of adopting a political economy approach in the analysis of informality and motivate how and why this may be useful for consideration in areas related to policy development and governance more broadly

Characteristics of local groundwater recharge cycles in South African semi-arid hard rock terrains – rainwater input

Rainfall events in semi-arid regions of South Africa are characteristically erratic in terms of depths and recurrence rates. Chemical assessment of cyclic rainwater has recognised 3 intervals, spaced over the hydrological cycle, reporting diverse hydrochemical compositions of rainwater in winter and summer rainfall regions. Winter rainwater is generated over thesouth Atlantic maritime waters. This rainwater contains noticeably higher concentrations of oceanic aerosols (NaCl) than the summer rainwater generated in the Intertropical Convergence Zone/equatorial western Indian Ocean. Sporadic addition of terrigenous dust generated over the continent substantially elevates concentrations of non-oceanic nitrogenous andsulphurous aerosols in the summer rainwater. Prominent seasonal variations in the rainwater hydrochemistry signature coincide with cyclic rainfall depths, characteristic of the semi-arid climate. Macro-element concentrations during the summer dry period, April to September, are relatively high in relation to those recorded for the wet cycle, October to March. However, the latter period reports a noticeably depleted hydrochemical rainwater input into the local groundwater budgetduring the peak rainfall period (January to March). The October-December (early) period represents a phase between a dusty, dry winter atmosphere and a relatively flushed atmosphere in December, after the first regional rainfall manifests around middle September. Individual early rainfalls contain even higher hydrochemical concentrations than the previousdry period, which subsequently diffuses as the airborne moisture content increases towards the peak rainfall period starting in January. Continuous rainfall event monitoring in the summer semi-arid regions identified short-term wet cycles containing extraordinary high rainfall events, referred to as episodic events. These wet cycles are highly erratic in time and maylast from 3 to 8 consecutive days with a recurrence rate of 1 in 5 years. The rainwater hydrochemistry signature differs significantly from the normal rainfall composition and represents a unique opportunity for tracing the infiltrating rainwater. For example, chloride concentrations from individual, high rainfall events (40 to 150 mm) may be as low as 0.4 mgE.-1, whereas the background value varies around 0.8 mgE.-1. Environmental chloride represents a conservative tracer for estimatingthe migration between rainwater and groundwater recharge. The concentration levels are not constant throughout the year and may lead to erroneous assumptions when performing groundwater recharge estimations using accumulated rainwater samples and uncontrolled groundwater sampling techniques

Characteristics of local groundwater recharge cycles in South African semi-arid hard rock terrains: Rainfall–groundwater interaction

The semi-arid and arid regions occupy almost two-thirds of South Africa and fall in the winter and summer rainfall zones of the sub-continent. The annual rainfall patterns can be regarded as intermittent with a significant spatial variability due to the unique winter/summer synoptic systems manifesting over Southern Africa. Summer rainfall events indicate that episodic wet periods, consisting of up to 8 consecutive days, may contain falls that contribute to almost 45% to 60% of the total annual rainfall of an area; associated with relatively higher rain rates (1.5 to 10 mm·h-1). Hyetograph-hydrograph time-series data sets, however, indicate that episodic rainfall events are responsible for rapid, but sustainable groundwater recharge events. The recurrence rate of these events in the semi-arid and arid regions is still low and aquifer storage-recharge is therefore not an annual event. The recharge flow path through the unsaturated zone reservoir plays an important role in the underdrainage flow pattern, and subsequently the saturated flow regime. It resembles a simple L-shaped flow path driven by direct recharge mounding in the fractured hard rock terrain and indirect recharge to the surrounding sub-reservoirs. The lag-times between rainfall events and water table responses were found to be significantly short; a matter of a few hours to less than a few days. Evidence of multi-modal, time-related infiltration phases during the summer early and peak rainfall intervals, governed by the field capacity status of the unsaturated zone reservoir and the growth status of the local vegetation, were observed. A unique rainfall pattern in semi-arid and arid regions is required before a sustainable aquifer storage-recharge condition develops and such incidences could be a one-in-several-year (5 to 9) event

From trauma debriefing to trauma support: a South African experience of responding to individuals and communities in the aftermath of traumatising events

This paper documents the approach and experience of Traumaclinic, a Cape Town based organisation offering a trauma support service. The controversy over single session debriefing interventions is examined and it is concluded that interventions that invite intense emotional expression should not be offered indiscriminately or forced on those who do not want them. When they do occur, they need to be carefully managed and take place over several sessions. A review of contemporary approaches to intervention following trauma highlights their comprehensive and flexible nature and the inclusion of multiple components that are introduced in a manner responsive to the needs of the situation. This is the basis of the current model used by Traumaclinic. The principles of that model are summarised and examples given of the application of the approach to specific cases

Histamine and Tyramine Content of South African Wine

The histamine content of 184 wines and tyramine content of 156 wines, produced in South Africa was measured. The histamine and tyramine content of the wine was found to be similar to those of wines produced in other countries. The average histamine content of South African red wines that had undergone malo-lactic fermentation was more than double that of red wines that had not undergone malo-lactic fermentation. All the red wines containing relatively large amounts of histamine had pH's above 3, 7. Six selected strains of malo-lactic bacteria were tested for their ability to form histamine and tyramine in white and red wine. No histamine or tyramine was formed

Francois Jacobus van Zyl, hoogleraar 1960-1978

Francois Jacobus van Zyl, professor 1960-1978Professor Francois Jacobus van Zyl (6th May 1913-) served as head of the Department of Science of Religion and Missiology, Faculty of Theology (Sec A),University of Pretoria, during the period 1960-1978. This article (compiled from two previously published articles) contains a short biography, a discussion of hisviews on theology, Science of Religion, Philosophy of Religion, and Missiology. He is portrayed as a theologian with Barthian convictions. He worked from a broad theological base which can be described as ‘theology of the Word’. His primary audience was the Nederduitsch Hervormde Kerk and his theological activities(especially in the period 1960-1983) must be seen in relation to his influential role in the same church

Trauma, resilience and vulnerability to PTSD : a review and clinical case analysis

This article begins with two case examples of a girl and an adolescent who were raped and developed chronic PTSD. These are used as a basis for understanding the role of a range of factors that are associated with resilience and vulnerability in the face of traumatic events. A literature review examines the proportion of individuals who develop PTSD following trauma and the factors associated with vulnerability and resilience. These include gender, developmental factors, social support and personality factors. Psychological factors associated with maintenance of chronic PTSD are also briefly reviewed. This material is used as a basis for reconsidering the case examples. Each case is formulated within a framework based on sources of vulnerability and qualities of resilience. Approaches to intervention are suggested that could address the range of factors making the individuals vulnerable to chronic psychological problems and support resiliency and recovery