University of South Africa

About: University of South Africa is a education organization based out in Pretoria, South Africa. It is known for research contribution in the topics: Context (language use) & Population. The organization has 8478 authors who have published 19960 publications receiving 237688 citations. The organization is also known as: Unisa.

Misfit dislocation generation in epitaxial layers

Abstract: The misfit between an epilayer and a substrate may be accommodated either by misfit strain or by misfit dislocations, or by both jointly. For an epitaxial monolayer (ML) a critical misfit, depending primarily on bonding, exists below which it is stable when in registry with the substrate. When growth continues with the formation of a multilayer, misfit dislocations will enter at some critical thickness. The main objectives of this article are to critically review theoretical work aimed at explaining (1) the conditions under which an epilayer will grow in a ML-by-ML fashion to yield a uniform film and (2) the reasons why observed critical thicknesses and residual strains are often significantly in excess of the predicted ones, in terms of equilibrium and non-equilibrium concepts. Both (1) and (2) are of great fundamental and technological interest.

Knowledge production through collaborative research in sub-Saharan Africa: how much do countries contribute to each other's knowledge output and citation impact?

Abstract: This paper examines co-authorship of research articles in Thomson Reuters citation indexes in order to assess knowledge co-production in selected sub-Saharan African countries. Two indicators, namely publications and citations, were analysed to establish the patterns of knowledge co-production and its scientific impact, respectively. The study found that knowledge production through collaborative research among sub-Saharan African countries is minimal and contributes only a small percentage when compared to collaboration between sub-Saharan African countries and their foreign counterparts. Similarly, the scientific impact of international collaboration was higher than that of continental collaboration. Countries belonging to the same geographic region contributed to each other's knowledge production more frequently than they did to the countries outside their region. It is recommended that, for knowledge co-production in sub-Saharan Africa to improve, various measures such as encouraging student and staff exchange, hosting more regional conferences and encouraging research networks need to be put in place.

Retaining professional nurses in South Africa: Nurse managers’ perspectives

Abstract: South Africa is experiencing a serious shortage of nurses, which has to be addressed to prevent crises in health care services. Previous studies (Fletcher 2001:324; Oosthuizen 2005:117) found that nurses change their work environment due to dissatisfaction with their job situations. This implies that creating a favourable environment in the workplace situation could help retain professional nurses in their posts, implying that retention strategies should be effective. An exploratory, descriptive, contextual and qualitative design was used to describe nurse managers’views on factors which could influence professional nurse retention, as well as their views regarding attributes that were required to enable them to contribute towards enhancing professional nurse retention. A purposive sample of nurse managers employed in public and private hospitals in the Gauteng province was selected. Semi-structured interviews were conducted with 21 nurse managers.The results were analysed qualitatively and contextualised within Vogt, Cox, Velthouse and Thames’s Cork-Top (Bottleneck) Theory of Nurse Retention (1983) and Lewin’s Force-Field Analysis Theory (1952). Factors pertaining to individual nurses, the organisation and nurse managers could influence the retention of professional nurses. Poor working conditions, long and inconvenient working hours,uncompetitive salaries and professional development of nurses have to be addressed to enhance professional nurses’ retention. Unsafe working environments and a lack of resources threaten the safety and well-being of nurses and patients and contribute to high turnover rates. Nurse managers have to address shortcomings in their managerial and leadership skills and implement changes within a multigenerational nursing workforce and challenging working environments. Opsomming Suid-Afrika ervaar ’n ernstige tekort aan verpleegkundiges wat aangespreek moet word ten einde krisisse in gesondheidsorgdienste te voorkom. Vorige studies (Fletcher 2001:324; Oosthuizen 2005:117) het bevind dat verpleegkundiges hulle werksomgewing verander as gevolg van ontevredenheid met hulle werksituasies. Dit impliseer dat die daarstelling van ’n gunstige omgewing in die werkpleksituasie, kan help om professionele verpleegkundiges in hulle poste te behou, wat beteken dat retensiestrategiee doeltreffend moet wees. ’n Verkennende, beskrywende, kontekstuele, kwalitatiewe ontwerp was gebruik om verpleegbestuurders se sienings te bekom, oor faktore wat professionele verpleegkundiges se retensie kan beinvloed, asook hulle sienings omtrent vereiste hoedanighede wat hulle in staat sou stel om professionele verpleegkundiges se retensie te bevorder. ’n Doelgerigte steekproef van verpleegbestuurders in openbare en private hospitale in die Gauteng provinsie is gekies. Semigestruktureerde onderhoude is met 21 verpleegbestuurders gevoer. Die resultate is kwalitatief ontleed en gekontekstualiseer volgens Vogt, Cox, Velthouse en Thames se Kurkprop Bottelnek(Cork-Top Bottleneck) Teorie van Verpleegretensie (1983) en Lewin se Kragveld Analise Teorie(1952). Faktore met betrekking tot individuele verpleegkundiges, die organisasie en verpleegbestuurders kan die retensie van professionele verpleegkundiges beinvloed. Swak werksomstandighede,lang en ongerieflike werksure, nie-mededingende salarisse en professionele ontwikkeling van verpleegkundiges moet aangespreek word om professionele verpleegkundiges se retensie te bevorder. Onveilige werksomgewings en ’n gebrek aan hulpbronne bedreig die veiligheid en die welsyn van verpleegkundiges en pasiente en dra by tot hoe omsetsyfers. Verpleegbestuurders moet die tekortkominge in hulle bestuurs- en leierskapsvaardighede aanspreek en veranderinge implementeer binne ’n multigenerasie verpleegwerkkrag en uitdagende werksomgewings.

Longitudinal displacement of the carotid wall and cardiovascular risk factors: associations with aging, adiposity, blood pressure and periodontal disease independent of cross-sectional distensibility and intima-media thickness.

Abstract: The recently discovered longitudinal displacement of the common carotid arterial wall (i.e., the motion along the same plane as the blood flow), may be associated with incident cardiovascular events and represents a novel and relevant clinical information. At present, there have only been a few studies that have been conducted to investigate this longitudinal movement. We propose here a method to assess noninvasively the wall bi-dimensional (two-dimensional [2-D], cross-sectional and longitudinal) motion and present an original approach that combines a robust speckle tracking scheme to guidance by minimal path contours segmentation. Our method is well suited to large clinical population studies as it does not necessitate strong imaging prerequisites. The aim of this study is to describe the association between the longitudinal displacement of the carotid arterial wall and cardiovascular risk factors, among which periodontal disease. Some 126 Indigenous Australians with periodontal disease, an emerging risk factor, and 27 healthy age- and sex-matched non-indigenous control subjects had high-resolution ultrasound scans of the common carotid artery. Carotid intima-media thickness and arterial wall 2-D motion were then assessed using our method in ultrasound B-mode sequences. Carotid longitudinal displacement was markedly lower in the periodontal disease group than the control group (geometric mean (IQR): 0.15 mm (0.13) vs. 0.42 mm (0.30), respectively; p < 0.0001), independent of cardiovascular risk factors, cross-sectional distensibility and carotid intima-media thickness (p < 0.0001). A multivariable model indicated that the strongest correlates of carotid longitudinal displacement in adults with periodontal disease were age (β-coefficient = −.235, p = .03), waist (β-coefficient = −.357, p = 0.001), and pulse pressure (β-coefficient = .175, p = 0.07), independent of other cardiovascular risk factors, cross-sectional distensibility and pulse wave velocity. Carotid longitudinal displacement, estimated with our approach, is impaired in the periodontal disease group, independent of established cardiovascular risk factors and other noninvasive measures of arterial stiffness, and may represent an important marker of cardiovascular risk.

Patterns, causes and consequences of land use/cover dynamics in the Gumara watershed of lake Tana basin, Northwestern Ethiopia

Abstract: This study was aimed at examining land use/cover changes over 48 years and its causative factors in the Gumara watershed of Lake Tana basin, Northwestern Ethiopia. Two sets of aerial photograph (1957 and 1985) and a multispectral Spot5 image (2005) were used as inputs to produce three GIS-based land cover maps of the study area. Socio-economic surveys, focus group discussion and field observation were also used to determine the cause and effects of these land use/cover dynamics. The results showed that cultivated and settlement land expanded by 21.99 %, whereas forest land, shrub land, grass land and wetland declined by 85.30, 91.39, 76.15 and 72.54 % over the analysis period respectively. Population pressure, demand for fuel wood and construction material, agricultural expansion and policy and tenure insecurity were the major driving forces behind the land use/cover change. Environmental and local livelihoods implications such as lake water and its aquatic resources and soil degradation, biodiversity loss and forest cover decline are resulted from the changes. The cumulative effect of these implications caused poverty and environmental degradation. Hence, there should be strategies of managing open access resources through participation of local people in the management. There should also be appropriate land use planning by identifying the proper land for specific purpose so that the marginal lands will not be put into agricultural use.