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Detecting the turnover of the power spectrum with SKAO and other surveys
(University of the Western Cape, 2025) Dube, Yolanda
Detecting the turnover of the power spectrum with SKAO and other surveys. This thesis explores the potential of next-generation experiments, specifically the Square Kilometre Array and the Dark Energy Spectroscopic Instrument, to detect and constrain the power spectrum turnover, a key feature of the universe’s large-scale structure holding the key for probing ultra-large scales. Employing intensity mapping and galaxy surveys, we utilize Fisher forecasts and Markov Chain Monte Carlo simulations to model and analyze this subtle cosmological signature. Our findings reveal that SKA-MID Band 1 demonstrates the highest detection significance and Figure of Merit, establishing it as the most promising instrument for this endeavor. However, foregrounds introduce a bias on the detected value of the turnover position. While DESI surveys excel at probing small-scale structures, they effectively complement intensity mapping surveys, crucial for a holistic understanding of the universe’s matter distribution. We address significant challenges such as foreground contamination and analyze the effects of the telescope beam, which can obscure the turnover signal for intensity mapping observations. Our study emphasizes the importance of advanced foreground cleaning techniques and beam-induced bias correction for accurate cosmological analysis. This work confirms the feasibility of detecting the power spectrum turnover with observational tools and provides a critical comparative evaluation of current methodologies across various surveys. The insights discussed lay a robust foundation for future research dedicated to refining our understanding of cosmic evolution and its governing parameters as well as addressing the Hubble tension.
Quality of care offered by health care retail markets for medication abortion self-management: Findings from states in Nigeria and India
(Public Library of Science, 2025) Omoluabi, Elizabeth; Shankar, Mridula; OlaOlorun, Funmilola Morinoye
Dispensing of misoprostol and mifepristone by pharmacies and chemist shops for self-management of medication abortion (MA) fills a crucial gap in settings where abortion care by trained health professionals is not readily available. This promising service delivery pathway, endorsed by the World Health Organization (WHO), is hindered by concerns of poor-quality care. Simulated clients collected data on MA pill dispensing practices from 92 pharmacies and chemist shops in three Nigerian states and 127 pharmacies in an Indian state that we have anonymized. Guided by the WHO’s abortion guideline, we measured process-related quality indicators such as medication use instructions, warning signs, and respectful treatment among other aspects. We aggregated indicators under three domains: technical competence, information given to clients, and client experience. Overall, 51% of facilities in the Nigerian states and 32% in the Indian state offered MA pills. Most dispensing facilities offered the misoprostol-only regimen in Nigeria (68%) and the combination regimen in the Indian state (83%). Among facilities offering MA pills, 26% in Nigeria and 78% in the Indian state provided correct instructions on route of pill administration. Accurate information on the appropriate interval between pill type in the combination regimen was low in Nigeria (27%) and the Indian state (14%). Excessive bleeding as a warning sign was discussed more frequently in the Indian (56%) versus Nigerian states (32%); other abnormal bleeding patterns were rarely mentioned. Aggregate technical competency scores were low at 18% in Nigeria and 34% in the Indian state, with highest scores for client experience at 90% and 91% respectively. Findings suggest that people using MA pills purchased from the retail market are not given accurate and adequate information for most effective self-use. If MA self-management remains outside regulatory boundaries, technical quality will remain sub-standard, imposing unnecessary costs to people, their health, and health systems.
A systematic review assessing the association between extreme temperature exposure and cardiovascular health outcomes in Africa
(Academic Press Inc., 2025) Sello, Mamakase G.; Kyeyune, Jemimah; Kgatla, Hellen; Mchiza, Zandile J
The African continent is grappling with a rising prevalence of cardiovascular diseases (CVDs) in conjunction with the growing threat of climate change and its associated extreme temperatures. This systematic review aims to assess the relationship between extreme temperature exposures (heat and cold exposure) and cardiovascular health outcomes in African populations. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed in compiling this evidence. A comprehensive literature search was performed on PubMed-Medline, Scopus, Web of Science, and Google Scholar as the primary databases to identify relevant studies published from January 1990 to October 2024. Both hot and cold temperature extremes were linked to detrimental cardiovascular outcomes related to stroke. Exposure to sudden drops in minimum temperature exceeding 2.4 °C was linked with a 43 % higher risk of stroke. Elderly women (≥65-years) exposed to cold had the highest mortality rates and were more vulnerable to air pollution interactions during moderate temperatures (20–23 °C). Exposure to high temperatures (>37 °C) was associated with increased rates of heart failure and stroke. Hypertension was identified as a significant risk factor, with 37.6 % of stroke patients having pre-existing hypertension; notably, 86.2 % of these cases were linked to heat exposure. The highest CVD vulnerability was observed among females, older adults, and rural dwellers. The evidence presented in this systematic review suggests that exposure to both extreme cold and heat significantly contributes to the development of cardiovascular diseases. However, further studies are needed to validate and strengthen these findings.
Assessing CO2 storage potential in a structurally complex depletedgas reservoir, offshore South Africa
(Elsevier Ltd, 2025) Mhlambi, Sanelisiwe; Agbor, Fritz Ako; van Bever Donker, Jan M
As global efforts to mitigate greenhouse gas emissions intensify, carbon capture and storage (CCS) has emerged as a key strategy for reducing the environmental impact of fossil fuel use. However, geological storage of CO₂ in structurally complex and heterogeneous reservoirs presents a range of issues due to the geological intricacies, with implications for storage capacity estimation, CO₂ injection, migration, and even long-term containment, which pose environmental risks. Therefore, this study assesses the CO₂ storage potential of the depleted F-O Gas Field in the Bredasdorp Basin, offshore South Africa, using a robust modelling approach based on the analysis of a suite of exploration and production datasets from the field. A high degree of structural compartmentalisation with a fault-bounded anticlinal trap characterises the field. The Valanginian-age marine sandstone reservoirs exhibit low to moderate porosity and permeability. In total, a CO₂ storage capacity of 185.3 Mt was determined for the F-O gas field, which reduces to 37.1–74.1 Mt after accounting for reservoir heterogeneity and sweep efficiency. This reduction reflects the impact of the field's complex structural architecture, variable facies distribution, and petrophysical variability, which collectively limit the effective pore volume accessible for CO2 storage. By rigorously integrating the structural architecture of the field, sedimentary processes, facies distribution, and petrophysical variability of the candidate reservoir, this study provides critical insights and strategies into the feasibility of CCS in structurally complex depleted gas fields. Significantly, these findings contribute to ongoing national CCS assessments and support South Africa's long-term decarbonisation agenda.
Estimation of hydrogeological spring catchment area: case of Jinci spring in North China
(Springer Nature, 2025) Xu, Yongxin; Zhang, Zhixiang; Wang, Zhaoliang
Hydrogeological spring catchment area of Jinci spring is the starting point for all hydrogeological analyses and one of the fundamental datasets for karst groundwater modeling. Unfortunately, there is a lack of detailed research on the hydrogeological spring catchment area. To sustainably utilize and protect the karst groundwater resources of Jinci spring, this paper investigates the variation pattern of the spring flow decrease coefficient from 1956 to 1994, estimates the hydrogeological spring catchment area by using the linear regression method and the Turc method. The results show that: (1) The spring flow decrease coefficient generally shows an increasing trend over time, and its variation indicates the time-varying characteristics of the hydrogeological spring catchment area. (2) The hydrogeological spring catchment areas estimated by the linear regression method are 2143, 2084 and 2037 km2, with an average of 2088 km2. (3) The hydrogeological spring catchment area estimated by the Turc method exhibits a series of values, and its time-varying characteristics is the dynamic change with time, resulting from the joint effects of natural and anthropogenic factors. This study provides a theoretical foundation for the protection and management of karst groundwater in the semi-arid region of northern China.