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A refusal to abandon HIV science
(Lippincott Williams and Wilkins, 2025-05) Hatcher, Abigail M.; Metheny, Nicholas; Dunkle, K.L.; Fielding-Miller, Rebecca
No abstract available.
Assessing the economic viability of sustainable pasture and rangeland management practices : a review
(MDPI, 2025-04) Rapiya, Monde; Mndela, Mthunzi;; Truter, Wayne; Ramoelo, Abel
The livestock sector is crucial for global food security and economic development, particularly in developing nations, as it supports the livelihoods of approximately 1.3 billion people. However, with the global population expected to reach 9.2 billion by 2050, the sector must address increasing demand for livestock products while ensuring environmental sustainability. This study used the available literature to evaluate the economic viability of sustainable pasture and rangeland management practices to enhance livestock production. The key findings demonstrate that strategies such as rotational grazing and nitrogen fertilization can decrease winter feed costs by up to 40% while simultaneously improving pasture productivity and animal weight gains. Initial investments in these improved forage practices offer high internal rates of return, indicating their profitability. To guide sustainable pasture production and rangeland management, we propose a conceptual framework that balances cultivated pastures and natural rangelands. This framework assesses critical factors, including input costs, expected outputs (enhanced biodiversity and livestock production), and interventions to mitigate land degradation. For successful adoption of these practices, targeted policies are essential. Governments should develop financial support mechanisms for smallholder farmers, improve transportation infrastructure for efficient feed logistics, and provide technical assistance to educate producers on sustainable practices. Engaging stakeholders to align policies with local needs is also vital. By implementing these strategic interventions, the resilience of livestock systems can be strengthened, contributing to long-term sustainability and supporting food security and rural community well-being.
Improved runs-rules precedence charts for monitoring the process location parameter
(Springer, 2025-04) Human, Schalk William; Malela-Majika, Jean-Claude; Kritzinger, Pierre; malela.mjc@up.ac.za
Runs-rules are typically incorporated into control charts to increase their sensitivity to detect small process shifts. However, a drawback of this approach is that the resulting charts are unable to detect large shifts quickly. In this paper, improved runs-rules are introduced to the nonparametric precedence chart to address this limitation by maintaining the sensitivity to small process shifts, while improving the ability to detect large shifts in the process. Performance comparisons between the proposed precedence charts and the precedence charts with standard runs-rules are made in terms of their respective run-length characteristics. The results reveal that the precedence charts with improved runs-rules are superior to the competing charts in detecting large shifts in the process, while maintaining the same sensitivity in the detection of small shifts. A real-life example from the engineering field is given to demonstrate the application and implementation of the new charts.
A power-cardioid candidate for wind direction modelling motivated by two South African case studies
(Springer, 2025-04) Van Wyk-de Ridder, Delene; Rad, Najmeh Nakhaei; Arashi, Mohammad; Ferreira, Johan; Bekker, Andriette, 1958-; johan.ferreira@up.ac.za
Wind energy claims a positive image globally; therefore, accurate modelling of wind direction at generation sites accurately can enhance the potential of this green energy source. The uncertain nature of wind direction can be modelled through probability distributions; in this paper, we propose a flexible yet simple distribution, namely the Power-Cardioid distribution, as an alternative and implementable candidate to model wind direction. After discussing some characteristics, the performance of the Power-Cardioid distribution is evaluated via a simulation study and applied to datasets of two wind farms in South Africa. The numerical results demonstrate that this distribution is a promising and exciting new candidate compared to well-known models within circular statistics.
Unpacking experienced and novice science teachers’ understandings of teacher talk in whole class discussions
(Routledge, 2025) Khoza, Hlologelo Climant; Magadlela, Nomhle; climant.khoza@up.ac.za
While there is a vast literature arguing that teacher talk in whole class discussions is a determinant of quality science teaching, teachers’ understanding of enacting teacher talk is under-researched. Using teacher cognition as a theoretical lens, the purpose of this study was to explore how experienced and novice science teachers in South Africa understand teacher talk in whole class discussions. Multiple case-study design was adopted and data was collected from thirteen science teachers through interviews. Six of these teachers were considered novices and seven were considered experienced. A thematic analysis approach was used to make sense of the data. The teachers’ nature of understanding was further categorised into authoritative, constructivist and transitional. A notable finding is that the majority of novice teachers displayed a constructivist profile while a majority of experienced teacher displayed an authoritative profile. Novice teachers seemed to understand a larger variety of ways to enact talk in whole class discussions regardless of their nature of understanding as compared with experienced teachers. However, the experienced teachers understanding revealed a distinct factor that influences talk, i.e. the sociolinguistic factor. In contrast, the novice science teachers emphasised their content knowledge as a contributing factor to teacher talk. We conclude that since the quality of science teaching is dependent on teacher talk, continued professional development to strengthen teacher talk is not only to be targeted at novice teachers but also at experienced teachers.