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Improved null tests of ΛCDM and FLRW in light of DESI DR2
(Institute of Physics, 2025) Dinda, Bikash; Maartens, Roy; Clarkson, Chris
The DESI DR2 BAO data, in combination with CMB and different SNIa datasets, exclude the flat ΛCDM model at more than 2.5σ when analyzed through the w 0 w aCDM parametrization for evolving dark energy. This simple parametrization may not accurately capture the behavior of the entire redshift range at late times, which may introduce bias in the results. We use null tests that probe for deviations from flat ΛCDM at late times, independent of any specific dark energy parametrization. We provide several diagnostics for null tests and discuss their advantages and disadvantages. In particular, we derive diagnostics that improve on previous ones, such as the popular O m diagnostic. The diagnostics are derived from both background and perturbed quantities. Using the combination of DESI DR2 BAO and supernova data, with or without CMB data, we find that deviations from flat ΛCDM are at ∼1σ confidence level in most of the redshift range (more than 1σ for a few small redshift intervals in a few cases). When considering SDSS BAO data instead of DESI BAO data, in combination with PantheonPlus, with or without CMB data, we find even smaller deviations. Since spatial curvature can potentially modify the results, we also test for curvature in the general ΛCDM model and the general FLRW model. While there is slight evidence for nonzero cosmic curvature at lower redshifts in a general ΛCDM model, there is no statistically significant evidence in a general FLRW model.
Persons with disabilities’ perceptions on self-employment barriers, facilitators and solutions in a rural setting – an exploratory qualitative study
(SAGE Publications Ltd, 2025) Soeker, Shaheed Mogammad; Monareng, Luther Lebogang; Naidoo, Deshini
Background: Self-employment is a prevalent employment or job placement option for persons with disabilities in developing countries like those in Africa. Objective: This research explored perceptions of self-employment barriers, facilitators and solutions among persons with disabilities in a rural South African setting. Methods: This is a qualitative, exploratory, descriptive study design. Purposive sampling was used to recruit ten persons with disabilities in microenterprises in a rural setting of KwaZulu Natal. One-on-one semi-structured interviews were conducted using a piloted question guide in their preferred language. Thematic data analysis was done using the hybrid inductive and deductive approaches. Data was managed using the NVIVO software. Results: Out of ten self-employed participants, nine were male, and one was female. None of the participants had passed grade 12 (a prerequisite for basic jobs and entry into tertiary education), and two had no education. Two themes emerged. Theme one: Participants identified personal, societal and role players related barriers and facilitators in self-employment. Persons with disabilities reported challenges in self-employment. Despite the challenges, they remained resolute in leveraging residual function (functional upper limbs and cognitive abilities) to operate their microenterprise and use their time constructively. Theme two: Persons with disabilities proposed assistance with setting up self-employment in microenterprises as a solution – “What I would need most from a professional…” The proposed solutions involved community-based outreach where key role players engage directly with persons with disabilities in their communities to identify and address their needs. Conclusions: Persons with disabilities in rural KwaZulu Natal seek tailored and transparent services to address barriers to self-employment and ensure the sustainability of their microenterprise.
H I intensity mapping with the MIGHTEE Survey: first results of the H I power spectrum
(Oxford University Press, 2025) Taylor, Russ; Santos, Mario G.; Townsend, Junaid; Taylor, Russ
We present the first results of the H I intensity mapping power spectrum analysis with the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) survey. We use data covering ∼ 4 square degrees in the COSMOS field using a frequency range of 962.5–1008.42 MHz, equivalent to H I emission in 0.4 < z < 0.48. The data consist of 15 pointings with a total of 94.2 h on-source. We verify the suitability of the MIGHTEE data for H I intensity mapping by testing for residual systematics across frequency, baselines, and pointings. We also vary the window used for H I signal measurements and find no significant improvement using stringent Fourier mode cuts. We compute the H I power spectrum at scales 0.5 Mpc−1 ≾ k ≾ 10 Mpc−1 in autocorrelation as well as cross-correlation between observational scans using power spectrum domain averaging for pointings. We report consistent upper limits of 29.8 mK2 Mpc3 from the 2σ cross-correlation measurements and 25.82 mK2 Mpc3 from autocorrelation at k ∼2 Mpc−1.The low signal-to-noise ratio in this data potentially limits our ability to identify residual systematics, which will be addressed in the future by incorporating more data in the analysis.
Advancement in electrochemical sensing of chloramphenicol in varying matrixes: a review
(Elsevier B.V., 2025) Mulaudji, Kgwadu Percy; Mokwebo, Kefilwe Vanessa; De Bruin, Franklin Quelain; Pokpas, Keagan; Ross, Natasha
Chloramphenicol (CAP) have demonstrated its broad effectiveness against bacterial infections. However, its persistence in the environment and potential toxicity led to strict global regulations limiting its use. As a result, rapid and accurate detection methods for CAP are being developed to protect public health and maintain regulatory compliance regarding its presence in the environment. Conventional analytical methods such as High-Performance Liquid Chromatography, Gas Chromatography, and Liquid Chromatography–Mass Spectrometry were commonly used for CAP detection. However, these conventional methods suffer challenges such as time-consumption, fabrication complexity, reproducibility, and cost. With electrochemical sensing techniques presenting varying valuable benefits, such as instant detection, low power consumption, simultaneous analysis, and portability, making them essential for timely monitoring of various analytes. The performance of electrochemical sensor is further boosted by integrating materials such as spinels, metal oxides, and metallic nanoparticles. These materials are broadly investigated as electrode interface components thanks to their features that collectively boost electrochemical sensor such as providing excellent electrical conductivity, distinct catalytic behavior, and larger surface areas. Furthermore, this paper reviews the impact of traditional and standards analytical methods, as well as their recent advancement based on the detection of CAP in aqueous media.
Economic freedom fighters: understanding their approach to race
(University of the Western Cape, 2024) Nikelo, Sabelisiwe
In the South African context, race plays a central role in its past and present, due to South Africa's history of colonialism and Apartheid. Non-racialism became a constitutional ideal in post-apartheid South Africa and remains enshrined within the South African Constitution. Yet race continues to play a central role in shaping socio-political experiences. In recent years, the South African political arena has become imbued with the use of race, especially to garner support from the electorate, leading to the development of a racialised political rhetoric. In this context, this study explores the Economic Freedom Fighter’s (EFF) approach to race within the context of the South African political landscape. Using Critical Race theory, this study investigates the EFF’s rhetoric to uncover the themes and strategies used in their approach to race. Founded in 2013, the EFF diverges from the African National Congress’s (ANC) vision of non-racialism by addressing race explicitly in its pursuit of socio-economic justice, which has resulted in many labelling the organisation as divisive and racist due to its racialised political rhetoric. It does this through a qualitative analysis of secondary data collection of sources: party statements, manifestos, and public speeches, interviews, books, book chapter’s newspaper articles, journal articles, speeches, YouTube videos, video, internet sources. The study analyses how the party’s racialised political rhetoric may influence the racial dynamics and contribute to the polarisation of South Africa both racially and politically, that has reliance on identity politics. The findings reveal that the EFF’s approach to race prioritises black South Africans' interests, rejects liberal non-racialism, and promotes a shared racial identity and collective action, using race as a rallying point and policy lens; while this mobilises support, it also risks deepening societal polarisation, which could destabilise social cohesion if not carefully managed. The study shows that the EFF’s approach is simultaneously critical, transformative and destructive. These insights contribute to a broader understanding of how political parties use elements of populism ideals to leverage identity politics, shedding light on the complexities of race in contemporary South African politics.