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An extended and extremely thin gravitational arc from a lensed compact symmetric object at redshift of 2.059
McKean, John P.; Spingola, C.; Powell, D.M.; Vegetti, S. (Oxford University Press, 2025-11)
Compact symmetric objects (CSOs) are thought to be short-lived radio sources with two lobes of emission that are separated by less than a kpc in projection. However, studies of such systems at high redshift are challenging due to the limited resolution of present-day telescopes, and can be biased to the most luminous objects. Here, we report imaging of a gravitationally lensed CSO at a redshift of 2.059 using very long baseline interferometry at 1.7 GHz. The data are imaged using Bayesian forward modelling deconvolution, which reveals a spectacularly extended and thin gravitational arc, and several resolved features within the lensed images. The surface brightness of the lensing-corrected source shows two mini-lobes separated by 642 pc in projection, with evidence of multiple hotspots that have brightness temperatures of 108 . 6 to 109 . 2 K, and a total luminosity density of 1026 . 3 W Hz−1 . By combining the well-resolved radio source morphology with previous multiwavelength studies, we conclude that this object is likely a CSO of type 2, and that the properties are consistent with the bow-shock model for compact radio sources. Our analysis highlights the importance of combining high-quality data sets with sophisticated imaging and modelling algorithms for studying the high-redshift Universe.
A spatially resolved spectral analysis of giant radio galaxies with MeerKAT
Charlton , K.K.L.; Delhaize, J.; Thorat, Kshitij; Heywood, I.; Jarvis , M.J.; Hardcastle, M.J.; An, F.; Delvecchio, I.; Hale, C.L.; Whittam, I.H.; Bruggen, M.; Marchetti, L.; Morabito, L.; Randriamanakoto, Z.; White, S.V.; Taylor, A.R. (Oxford University Press, 2025)
In this study we report the spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in the COSMOS field: MGTC J095959.63 + 024608.6, MGTC J100016.84 + 015133.0, and MGTC J100022.85 + 031520.4. One of these galaxies, MGTC J100022.85 + 031520.4, is reported here for the first time, with a projected linear size of 1.29 Mpc at a redshift of 0.1034. Unlike the other two, it is associated with a brightest cluster galaxy (BCG), making it one of the few GRGs known to inhabit cluster environments. We examine the spectral age distributions of the three GRGs using new MeerKAT UHF-band (544–1088 MHz) observations, and L -band (900–1670 MHz) data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. We test two models of spectral ageing, the Jaffe–Perola and Tribble models, using the Broadband Radio Astronomy Tools ( BRATS ) software, and find that they agree well with each other. We estimate the Tribble spectral age for MGTC J095959.63 + 024608.6 as 68 Myr, for MGTC J100016.84 + 015133.0 as 47 Myr, and for MGTC J100022.85 + 031520.4 as 67 Myr. We find significant disagreements between these spectral age estimates and the estimates of the dynamical ages of these GRGs, modelled in cluster and group environments. Our results highlight the need for additional processes that are not accounted for in either the dynamic age or the spectral age estimations.
Assessment and characterization of the impact of pulmonary pathology on flow-induced acoustics using computational fluid dynamics
Makhanya, Khanyisani Mhlangano; Bhamjee, Muaaz; Martinson, Neil; Connell, Simon (Elsevier, 2026-07)
Please read abstract in the article. HIGHLIGHTS • Novel CFD approach to analysis of cough acoustics for pulmonary disease assessment • Studied Healthy lungs, pneumonia, bronchiectasis and cavitary tuberculosis • Method validated against 22 patient recordings with distinct clinical diagnoses • Model correlations with recordings advance understanding of respiratory acoustics • Potential to generate synthetic data to train AI model for telemedicine diagnoses
Assessment accommodations for autistic learners in South African schools : stakeholder perspectives
Nell, Yvonne; Kritzinger, Alta M. (Aletta Margaretha); Graham, Marien A.; Eccles, Renata (AOSIS, 2026-02-28)
BACKGROUND : Autistic learners benefit from demonstrating academic knowledge with the help of assessment accommodations, guided by South African examination policies, such as the National Policy Pertaining to the Conduct, Administration and Management of Examinations and Assessment for the National Senior Certificate Examination. However, stakeholder perspectives on accommodations remain under-explored. OBJECTIVES : This study explored stakeholder perspectives (autistic adults, caregivers, educators, psychologists, speech-language therapists and occupational therapists) on assessment accommodations for autistic learners in South African schools. METHOD : A web-based questionnaire was distributed nationally to professionals and caregivers (n = 92). Quantitative data were analysed descriptively, and qualitative responses were thematically coded. RESULTS : Stakeholders reported a persistent policy-practice disconnect, with educators lacking the knowledge of accommodation policies, as well as the training to implement accommodations, particularly for autistic learners. Similarly, current policies do not adequately accommodate the needs related to sensory regulation and anxiety. Considerable variability emerged in accommodation preferences, reflecting both the heterogeneity of autistic learners and the differences across stakeholder groups. Respondents also prioritised universal design elements such as simplified language, redundancy and clearer assessment layouts, which are not currently considered in South African policy. Overall, findings highlight the need for expanded and individually tailored assessment accommodations informed by diverse stakeholder input. CONCLUSION : The findings highlight a disconnect between policy and practice. Broader autism-specific accommodations are crucial to support equitable assessment conditions in South African schools, especially for learners with sensory and communication challenges. CONTRIBUTION : This study provides insight into stakeholder experiences and suggests that current assessment policies may inadvertently exclude autistic learners. The findings support the need for inclusive, contextually relevant assessment strategies. The contribution aligns with the focus of the journal on disability inclusion by advancing evidence-based recommendations that promote full participation of neurodivergent learners in education systems, particularly within under-resourced and diverse settings.
Assessing the reliability of saw mark features : a comparative study using stereomicroscopy, micro-XCT, and 3D printing
De Wet, Pieter Daniël; Ridel, Alison Fany; Hagg, Alieske Christiene; Hoffman, Jakobus W.; L'Abbe, Ericka Noelle (Wiley, 2026)
Saw mark analysis is an important component of forensic anthropology, particularly in cases of postmortem dismemberment. While stereomicroscopy remains the benchmark for evaluating kerf features, recent advances in imaging technologies offer new opportunities for documenting and interpreting bone trauma. Although these modalities have been studied individually, few investigations have directly compared their relative strengths and limitations. Four fresh human femora were sectioned using six teeth per inch ripsaw to produce 32 false starts and 64 complete cuts. Sixteen kerf features were assessed across stereomicroscopy, micro-focus X-ray computed tomography (micro-XCT), and three-dimensional printed bone models, with scoring for presence, absence, or type, and quantitative measurement where applicable. In addition, a subset of 10 false starts and 10 complete cuts were selected for observer error testing. Minimum kerf width and kerf wall shape showed the highest agreement across observers and modalities, while features such as kerf flare, pull-out striae, and residual kerf wall striae demonstrated lower agreement. Stereomicroscopy provided the highest resolution for fine surface features, whereas micro-XCT enhanced non-destructive visualization of internal kerf morphology and fracture-related traits. Three-dimensional printed models reliably reproduced broader qualitative features but lacked sufficient resolution for fine-scale traits and precise measurements. Significant differences between modalities were observed for several features, emphasizing the influence of visualization method on feature detection and measurement. These findings highlight the need for standardized feature definitions and modality-specific scoring protocols. A multimodal approach of the three modalities is recommended to strengthen the reliability, interpretive value, and forensic applicability of saw mark analysis. HIGHLIGHTS • Observer error evaluation and feature comparison using a single saw across three modalities. • Minimum kerf width, kerf floor, and kerf wall shapes are most reproducible; micro-XCT shows the best agreement. • Stereomicroscopy provided the highest resolution for fine kerf features and striae. • Non-destructive imaging improved detection of spalling and internal kerf traits. • Bone models 3D printed lacked fine detail for analysis but can be used for teaching purposes.