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- ItemOpen AccessThe rise of quantitative work in economics(2026) Makhathini, Sbongakonke Sandisiwe; Georg, Co-PierreThe evolution of economic journals from 1940 to 2010 reflects a growing reliance on quantitative methods, driven by the increasing availability of data and the need for research to address complex economic challenges. This study analyses trends in the use of equations, figures, and tables across five leading economics journals—American Economic Review, Econometrica, Journal of Political Economy, Quarterly Journal of Economics, and Review of Economic Studies—to investigate the empirical turn in economics. Regression analysis reveals significant increases in the use of quantitative methods over time, with z-scores identifying critical periods of change. These shifts are influenced by editorial mandates, historical economic events, and technological advancements. The findings underscore the methodological transformation of economics and its implications for the discipline's engagement with empirical and policy-relevant questions.
- ItemOpen AccessDocumenting indigenous knowledge systems' role within the governance of marine and coastal conservation in South Africa - a Sokhulu case study(2026) Lebeko, Tlotlo Bridgette; Mbatha, Philile; Kozanayi, WitnessA vast body of literature provides historical accounts of the establishment of nature conservation interventions and their manifestations in post-colonial Africa. These studies highlight the impact of Western conservation ideals on the relationship between African Indigenous People and Local Communities (IPLCs) and nature and how natural resource governance was constituted. Narratives of disenfranchisement, dispossession, and marginalisation emerge centrally. Local people were stripped from their ancestral lands, disconnected from historical rights and access to natural resources, and subjected to the systematic erasure of Indigenous and local ecological knowledge. This paves the way for a Western-constructed ideal of ‘pristine', ‘wilderness', and ‘biodiversity' protection. This has placed significant focus on managing marine and coastal environments and resources. Building on these historical dynamics of nature conservation in practice and its impact on IPLCs, this research project uses the rural coastal community of Sokhulu in northern Kwa- Zulu Natal, South Africa, as a lens to enhance an in-depth understanding of what local ecological knowledge of IPLCs constitutes, with the view to contributing to how it can be incorporated into conservation planning, processes, and practices where the inclusion of IPLCs is increasingly being encouraged. Documenting oral histories of this community underscores how Afrocentric Indigenous Knowledge systems (AIKS), guided by the principle of respect, continue to function as a local approach to ecological governance in post-apartheid South Africa. It responds to global sustainable development policy calls (i.e Agenda 21, Sustainable Development Goals (SDGs), the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IBPES), and Kunming-Montreal Framework (K-M GBF) and illustrates the rich knowledge present in this community by demonstrating the importance of effectively integrating IPLCs into natural resource governance.
- ItemOpen AccessArms diplomacy, bicycle diplomacy, and flag money: the selection of an American Ally in Angola(2026) Jellema-Butler, Julia; Seegers, AnnetteMany civil wars are fuelled by the receipt, by one or more armed groups, of material support from a foreign third-party state. Such rebel patronage injects traces of international conflict and international cooperation into civil conflicts, and it often shapes their outcomes. But understanding rebel patronage strategies requires developing models to explain how state patrons select their foreign rebel clients, and such models remain at an early stage of theoretical development. Using process-tracing and original historical research, this dissertation tests theoretical hypotheses about rebel selection by examining American support to Angolan nationalist groups during the first phase of the Angolan Civil War in 1975. In particular, it seeks to explain the transformation in the relationship between the United States and the National Union for the Total Independence of Angola (União Nacional para a Independência Total de Angola; UNITA), which the White House declined to support in January 1975 but included in a multimillion- dollar support package in July 1975. The most decisive factors in this transformation, it emerges, were political. UNITA's rise in American esteem was closely related to the group's newfound closeness with American allies in Angola's neighbouring countries, who shaped the American patronage strategy. It was also influenced by the White House's increasingly ambitious political objectives in Angola. The Angolan case study thus provides support to an emerging body of literature that suggests that rebel selection decisions may be closely conditioned on the objectives of the intervention and on the expected policy positions of other third-party states.
- ItemOpen AccessThe relationship between organophosphate pesticide exposure and anthropometric outcomes among a cohort of children from four informal settlements in the Western Cape(2026) Wallace, Hayley Marget; Dalvie, Aqiel; Olaniyan, ToyibObjective: There is limited data on the association between pesticide exposure in children and anthropometric outcomes, particularly in non-agricultural communities and developing countries. This study investigated the association between organophosphate pesticide (OPP) exposure and anthropometric outcomes in primary schoolchildren from four informal settlements in Western Cape Province in South Africa. Methods: This study was a repeated cross-sectional study of 600 schoolchildren over a 12-month period. Measurements included urinary dialkyl phosphate (DAP) metabolites [diethylphosphate (DEP), dimethylphosphate (DMP), and dimethylthiophosphate (DMTP)] at baseline and DEP and DMP at follow-up. Individual level characteristics as well as anthropometric measurements [height, weight, and Body Mass Index (BMI)] were collected at both time points. Results: The mean age for all participants at baseline was 9.93 ± 0.90 years and mean ∑DAP at baseline was 41.78 ± 33.80 ng/ml. Mean changes in weight, height, and BMI from baseline to follow-up for all participants were 6.04 ± 5.29 kg, 6.83 ± 4.00 cm, and 1.05 ± 2.01 kg/m2, respectively. Eighty percent of participants measured below the 50th percentile in height-for-age at baseline, and 76.8% at follow-up. Although not all reached statistical significance, besides the association of the sum of DAP at follow-up (OR: 2.23, 95% CI: 1.09 – 4.57), all the other measures of urinary DAP were positively associated with low BMI-for-age (i.e., BMI values below two standard deviations of the WHO growth chart reference). Conclusion: Urinary OPP metabolite measurements and the prevalence of short stature among children in the study were high compared to other settings. The study found some evidence of decreased BMI-for age with increasing DAPs concentrations among the participating children. Large longitudinal studies with follow-up periods exceeding two years and incorporating pesticide biomonitoring at multiple time-points are recommended. Additionally, policy and intervention to reduce pesticide exposures in non-agricultural communities are recommended.
- ItemOpen AccessEnhancing species distribution models through integrated modeling and bias mitigation in African bird studies(2026) Jiang, Wenjie; Ngwenya, MzabalazoThe increasing availability of biodiversity data provides significant opportunities to improve species distribution modeling, particularly through the integration of multiple datasets. The overarching aim of this dissertation is to construct an integrated species distribution model (ISDM) for African bird species. A central challenge in developing ISDMs is that different datasets follow distinct sampling protocols and embody different assumptions. In particular, widely available presence-only (PO) data are prone to severe sampling bias, which can substantially distort model inference if not properly addressed. In this dissertation, we evaluate how sample size, degree of spatial bias, and species preva- lence influence the accuracy and stability of ISDMs. This is achieved through simulation experiments using the virtual ecologist approach, which allows controlled manipulation of eco- logical and sampling processes. We also examine methods for mitigating sampling bias in PO datasets, including modeling the bias using covariates and incorporating an additional spatial random field specifically designed to account for the bias component. Our simulation results show that when the volume of presence-only data greatly exceeds that of presence-absence (PA) data, the PO dataset dominates model behaviour, resulting in decreased precision and reduced predictive performance. Consequently, when applying ISDMs to real-world data, PO data must be thinned to reduce the influence of sampling bias. Guided by the insights gained from the simulation study, ISDMs were then constructed for three African bird species with differing ecological and data-related characteristics. These models were developed using eBird (PO) data and SABAP2 (PA) data. As informed by the simulations, the eBird dataset was thinned prior to model construction, with thinning intensity determined using the inhomogeneous pair correlation function to minimise residual sampling bias.