University of Johannesburg

About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Tourism. The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

An assessment of the influence of multiple stressors on the Vaal River, South Africa

Abstract: The Vaal River is situated in the mining and industrial heartland of South Africa. It is regarded as a “work horse” river in South Africa and as a consequence it receives treated waste water from the largest metropolitain area in South Africa. It is only with the more frequent occurance of fish kills in the Vaal Barrage area during the past few years that public attention has been drawn towards the decreasing water quality and subsequent deterioration in the aquatic health of the Vaal River system. The aim of this study was to apply a multi-metric approach to assessing the risk of the multiple stressors to fish populations of the Vaal River system. A relative risk assessment approach was applied to divide the Vaal River Barrage into four risk regions. Field sampling was undertaken to validate the predicted risks in each region. The sampling included abiotic (i.e. water and sediment quality) and biotic (fish components) assessment. General water quality parameters (pH, conductivity, dissolved oxygen) together with nutrient, bacteriological and metal concentrations were measured in the four regions. Sediment quality was determined through physical (particle size distribution) and chemical (metal and organic pollutant) analyses. The fish assessment was undertaken at different levels of biological organisation ranging from biomarkers at subcellular levels (cytochrome P450-EROD, metallothionein, acetycholine esterase, antioxidant enzymes, cellular energy), tissue (histopathology), whole organism (fish health index), population and community level. These biological responses were related to environmental exposure through bioaccumulation analyses of metals and organic pollutants in fish tissues. Multivariate statistical analyses were applied to integrate the environmental exposure and effects. The results indicated that those regions that were predicted to be at greatest risk to exposure of multiple stressors did indeed display the greatest disturbance in fish community structures. This was related to decreased fish health as demonstrated by increased oxidative stress due to exposure to metals such as copper and nickel as well as organic pollutants such as PCBs, HCHs and bromated flame retardants. This study clearly demonstrates the importance of the inclusion of higher tier assessment endpoints to elucidate the effects of multiple stressors in aquatic ecosystems. The study further allowed for the identification of specific effect endpoints that need to be included in future monitoring programmes such as viral immunoassays.

Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing

Abstract: NASA [NNX13AC26G, NNX13AC63G, NNX13AE99G, NNH13CH61C]; NSF [AST-1412693, AST-1253702, AST-1211916, AST-1009571, AST-1210311, AST-1412315]; STFC [ST/M001296/1]; National Research Foundation (NRF) of South Africa; UK Space Agency; TABASGO Foundation; Christopher R. Redlich Fund; Packard Foundation; Danish Council for Independent Research [DFF 4002-00275]

Work-based identity and work engagement as potential antecedents of task performance and turnover intention: Unravelling a complex relationship

Abstract: Orientation: Work-based identity, used as a reference to the self, is the answer to the question ’Who am I at work?’ Work-related identities, derived from different social foci through identity formation processes, have as behavioural guides a significant influence on employee behaviour, which, in turn has an impact on work outcomes. Engagement, presented in different conceptualisations, is viewed by practitioners and academic researchers as an important antecedent of employee behaviour. Research purpose: The main purpose of the study was to investigate whether work-based identity and work engagement differed (in combination with personal alienation, helping behaviour and burnout) as potential antecedents (amongst numerous others) of task performance and turnover intention. Research design: A census-based sampling approach amongst 23 134 employees in the employment of an ICT company yielded a sample of 2429 usable questionnaires. Scales used in the study were the Maslach Burnout Inventory (MBI-HSS-20), Utrecht Work Engagement Scale (UWES), Work-based Identity, Personal Alienation, Helping Behaviour, Turnover Intention and Task Performance Scales. Main findings: The findings indicate that work-based identity and work engagement give similar appearing results as potential predictors of turnover intention and task performance. Practical/managerial implications: Reducing withdrawal behaviours and enhancing work performance are everyday challenges for organisations. Interventions focused on enhancing work-based identity and work engagement in the work environment should have a meaningful impact when these behaviours need to be addressed. Contribution/value-add: Work-based identity as a multidimensional construct has the potential, with further refinement, to become a valuable construct that can play a leading role in future work engagement research.