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Tracing AGN–galaxy co-evolution with UV line-selected obscured AGN
(Oxford University Press, 2025) Jarvis, Matthew; Whittam, Imogen; Barchiesi, Luigi
Understanding black hole–galaxy co-evolution and the role of active galactic nucleus (AGN) feedback requires complete AGN samples, including heavily obscured systems. Such sources are key to constraining the black hole accretion rate density over cosmic time, yet they are challenging to identify and characterize across most wavelengths. In this work, we present the first ultraviolet (UV) line-selected ([Nev]3426 Å and Civ 1549 Å) sample of obscured AGN with full X-ray-to-radio coverage, assembled by combining data from the Chandra COSMOS Legacy survey, the COSMOS2020 UV–NIR catalogue, mid- and far-IR photometry from XID+, and radio observations from the Very Large Array and MeerKAT International GHz Tiered Extragalactic Exploration Survey (MIGHTEE) surveys. Using cigale to perform spectral energy distribution (SED) fitting, we analyse 184 obscured AGNs at 0.6 < z < 1.2 and 1.5 < z < 3.1, enabling detailed measurements of AGN and host-galaxy properties, and direct comparison with simba hydrodynamical simulations. We find that X-ray and radio data are essential for accurate SED fits, with the radio band proving critical when X-ray detections are missing or in cases of poor IR coverage. Comparisons with matched non-active galaxies and simulations suggest that the [Nev]-selected sources are in a pre-quenching stage, while the Civ-selected ones are likely quenched by AGN activity. Our results indicate that [Nev] and Civ selections target galaxies in a transient phase of their co-evolution, characterized by intense, obscured accretion, and pave the way for future extensions with upcoming large area high-z spectroscopic surveys.
Prevalence of metabolic syndrome among adolescents in Cape Town, South Africa: a cross-sectional analysis comparing five diagnostic criteria to explore suitability
(Elsevier Ireland Ltd, 2026) Wentzel, Annalie; Mchiza, Zandile June Rose; Nguyen, Kim Anh
Background: Metabolic syndrome (MetS) among adolescents is a growing public health concern globally, yet data from sub-Saharan Africa remain scarce. Variability in diagnostic criteria further complicates surveillance efforts. This study aimed to estimate the prevalence of MetS among adolescents in Cape Town, South Africa, using five diagnostic criteria, to assess the agreement between definitions and explore criteria suitability. Methods: We conducted a cross-sectional study among 489 adolescents aged 13–18 years, sampled from coeducational public high schools in Cape Town's Metro South district. Anthropometric, blood pressure, and fasting biochemical measurements were collected. MetS prevalence was assessed using the Cook, Ford, de Ferranti, International Diabetes Federation (IDF), and Agudelo criteria. Agreement between definitions was evaluated using unweighted Kappa statistics. Results: The MetS prevalence with four criteria were similar, ranging from 4.7 % (IDF) to 5.7 % (Ford), while one criterion differed significantly with 17.8 % (de Ferranti). Central obesity and raised blood pressure were the most prevalent MetS components across criteria. Females exhibited higher MetS prevalence than males across the five criteria. Very good agreement was observed between Cook, Ford, and Agudelo definitions (κ > 0.85), while agreement involving IDF and de Ferranti definitions was fair to moderate (κ = 0.33–0.42). Conclusions: Our results underscore the need for locally validated, population-specific MetS criteria and diagnostic thresholds to support early identification of adolescents at risk of cardiometabolic disease (CMD). In the absence of such criteria, the Cook and Ford definitions appear particularly suitable for identifying MetS among South African adolescents, while the Agudelo definition is appropriate when waist circumference (WC) measures are unavailable. Finally, our findings reveal a concerning CMD risk profile among adolescents in Cape Town, South Africa, with a particularly high burden observed in females.
A place-based assessment of biodiversity intactness in sub-Saharan Africa
(Nature Research, 2025) Maritz, Bryan; Clements, Hayley S; Biggs, Reinette
Maintaining biodiversity is central to the sustainable development agenda1. However, a lack of context-specific biodiversity information at policy-relevant scales has posed major limitations to decision-makers2,3. To address this challenge, we undertook a comprehensive assessment of the biodiversity intactness of sub-Saharan Africa4 using place-based knowledge of 200 African biodiversity experts5. We estimate that the region has on average lost 24% of its pre-colonial and pre-industrial faunal and floral population abundances, ranging from losses of <20% for disturbance-adapted herbaceous plants to 80% for some large mammals. Rwanda and Nigeria are the least intact (<55%), whereas Namibia and Botswana are the most intact (>85%). Notably, most remaining organisms occur in unprotected, relatively untransformed rangelands and natural forests. Losses in biodiversity intactness in the worst-affected biomes are driven by land transformation into cropland in grasslands and fynbos (Mediterranean-type ecosystems), by non-agricultural degradation in forests and by a combination of the two drivers in savannas. This assessment provides decision-makers with multifaceted, contextually appropriate and policy-relevant information on the state of biodiversity in an understudied region of the world. Our approach could be used in other regions, including better-studied localities, to integrate contextual, place-based knowledge into multiscale assessments of biodiversity status and impacts.
Quantifying the fatal and non-fatal burden of disease associated with child growth failure, 2000–2023: a systematic analysis from the global burden of disease study 2023
(Elsevier B.V., 2026) Okonji,Osaretin Christabel; Troeger, Christopher E; Arndt, Michael Benjamin
Background: Child growth failure (CGF), which includes underweight, wasting, and stunting, is among the factors most strongly associated with mortality and morbidity in children younger than 5 years worldwide. Poor height and bodyweight gain arise from a variety of biological and sociodemographic factors and are associated with increased vulnerability to infectious diseases. We used data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023 to estimate CGF prevalence, the risk of infectious diseases associated with CGF, and the disease mortality, morbidity, and overall burden associated with CGF. Methods: In this analysis we estimated the all-cause and cause-specific (diarrhoea, lower respiratory tract infections, malaria, and measles) disability-adjusted life-years (DALYs) lost and mortality associated with stunting, wasting, underweight, and CGF in aggregate. We combined the burden associated with mild, moderate, and severe forms of CGF: stunting was defined as height-for-age Z scores (HAZ) less than –1, underweight was defined as weight-for-age Z scores (WAZ) less than –1, and wasting was defined as weight-for-height Z scores (WHZ) less than –1, according to WHO Child Growth Standards. Population-level continuous distributions of HAZ, WAZ, and WHZ were estimated for 2000 to 2023 using data from surveys, literature, and individual-level study data. The risk of incidence of, and mortality due to, diarrhoea, lower respiratory infections, malaria, and measles was separately estimated in a meta-regression framework from longitudinal cohort data for Z scores less than –1. Finally, fatal outcomes associated with these diseases were estimated with vital registration, verbal autopsy, and case-fatality data, while non-fatal outcomes were estimated with surveys as well as health-care utilisation and case reporting data. The exposure prevalence and relative risk estimates were from continuous distributions, allowing for direct assessment of the attributable fractions for mild, moderate, and severe stunting, underweight, wasting, and the combined impact of child growth failure within populations.
The potential for urban agriculture (UA) in Cape Town, South Africa: a suitability analysis
(Taylor and Francis Ltd, 2025) Kanosvamhira, Tinashe Paul; Musasa, Tatenda; Mupepi, Oshneck
Urban agriculture plays a pivotal role in enhancing human well-being by contributing to food security, economic prosperity, and environmental sustainability. Despite its significance, many cities lack accurate inventories to identify suitable sites for such initiatives. This study examines the potential for urban agriculture in Cape Town using Multi-Criteria Decision Making techniques. Factors such as temperature, soil fertility, road accessibility, and precipitation were analysed using weighted overlay to determine the agricultural potential in Cape Town. Utilizing methodologies like the Analytic Hierarchy Process and Weighted Linear Combination, the agricultural potential was established. Findings indicate that there are highly suitable areas for agriculture whose potential has not yet been fully exploited. Currently, agricultural activities like vineyards, crop production, and cattle farming, though situated on good agricultural land, are not as prominent despite the availability of vast tracts of highly suitable land. Therefore, there is a need to raise awareness and promote urban agriculture to alleviate poverty-related food insecurities. The implementation of urban agriculture is anticipated to significantly improve food security, create economic opportunities, and enhance environmental sustainability within urban areas. The study recommends the need for longitudinal studies to gather essential information for informed decision-making, ensuring the sustainability of urban agriculture initiatives.