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Energy flux decomposition in magnetohydrodynamic turbulence
(Cambridge University Press, 2025) Capocci, Damiano; Johnson, Perry L.; Oughton, Sean; Biferale, Luca; Linkmann, Moritz
In hydrodynamic (HD) turbulence, an exact decomposition of the energy flux across scales has been derived that identifies the contributions associated with vortex stretching and strain self-amplification (Johnson, Phys. Rev. Lett., vol. 124, 2020 104501; J. Fluid Mech., vol. 922, 2021, A3) to the energy flux across scales. Here, we extend this methodology to general coupled advection-diffusion equations and, in particular, to homogeneous magnetohydrodynamic (MHD) turbulence. We show that several MHD subfluxes are related to each other by kinematic constraints akin to the Betchov relation in HD. Applied to data from direct numerical simulations, this decomposition allows for an identification of physical processes and for the quantification of their respective contributions to the energy cascade, as well as a quantitative assessment of their multi-scale nature through a further decomposition into single- and multi-scale terms. We find that vortex stretching is strongly depleted in MHD compared with HD, and the kinetic energy is transferred from large to small scales almost exclusively by the generation of regions of small-scale intense strain induced by the Lorentz force. In regions of large strain, current sheets are stretched by large-scale straining motion into regions of magnetic shear. This magnetic shear in turn drives extensional flows at smaller scales. Magnetic energy is transferred from large to small scales predominantly by the aforementioned current-sheet thinning in regions of high strain. The contributions from current-filament stretching - the analogue to vortex stretching - and from bending of magnetic field-lines into current filaments by vortical motion are both almost negligible, although the latter induces strong backscatter of magnetic energy. Consequences of these results for subgrid-scale turbulence modelling are discussed.
Latin bitrades derived from quasigroup autoparatopisms
(Springer Nature, 2025) Cavenagh, Nicholas J.; Falcón, RM
In 2008, Cavenagh, Drápal and Hämäläinen described a method of constructing Latin trades using groups. The Latin trades that arise from this construction are entry-transitive (that is, there always exists an autoparatopism of the Latin trade mapping any ordered triple to any other ordered triple). Moreover, useful properties of the Latin trade can be established using properties of the group. However, the construction does not give a direct embedding of the Latin trade into any particular Latin square. In this paper, we propose a similar approach to the above to construct Latin trades embedded in a Latin square L, via the autoparatopism group of the quasigroup with Cayley table L. We apply this theory to identify non-trivial entry-transitive trades in some group operation tables as well as in Latin squares that arise from quadratic orthomorphisms.
Emotional and physical challenges faced by parents and caregivers of children with autism spectrum disorder
(The University of Waikato, 2026) Kikale, Viraj Vikram; Curtis, Cate
Autism spectrum disorder (ASD) has a significant impact on the broader family, with parents and other carers experiencing high levels of parenting stress, caregiver burden and psychological distress. A body of research has explored emotional and practical/physical impacts of ASD caregiving, but the degree to which these outcomes co-occur across child, carer and contextual factors has not been synthesised within recent quantitative evidence. This systematic review aimed to synthesise quantitative empirical studies published mainly from 2015 onwards for exploring emotional and physical/practical caregiving outcomes in ASD caregiving. Methods: PsycINFO, PubMed, Scopus, Web of Science, CINAHL and ERIC were searched using pre-defined eligibility criteria. One hundred and fourteen records were screened and twenty studies were included in the main synthesis and additional sources were used for contextual and measurement purposes, but were not counted as included studies. Data were extracted and synthesised using structured narrative comparison, with consideration of methodological quality and contextual moderators. Across included studies, child clinical characteristics and caregiving context were commonly associated with variation in carer outcomes, including psychological distress and indicators of practical/physical burden (e.g. time demands and fatigue where measured). Carer characteristics (including gender, socioeconomic circumstances, health status, resilience and social support) were frequently explored as correlates or moderators. Intervention studies most commonly reported modest improvements in carer distress, while practical/physical caregiving demands were less consistently targeted where structural caregiving responsibilities remained unchanged. Methodological limitations commonly identified included the use of cross-sectional designs, dominance of self-report measures and poor representation of fathers and non-Western samples. This review emphasizes the multidimensional and context-dependent nature of ASD caregiving outcomes and highlights key priorities for enhancing the rigour of future quantitative research in this field.
Biomechanical determinants of placekicking success in professional Rugby Union players
(Taylor & Francis, 2020) Hébert-Losier, Kim; Lamb, Peter; Beaven, Christopher Martyn
The ability to score from placekicks discriminates winning from losing Rugby Union teams. We aimed to identify which biomechanical variables related to successful placekicking in professional Rugby Union players, and use self-organising maps (SOM) to determine whether meaningful sub-groups existed. Three professional placekickers performed 10 kicks outdoors. Placekicks were categorised into best, worst, and typical performances based on outcomes and coach and player perceptions. Seven 3D biomechanical variables consistently and meaningfully (moderate Cohen’s effect size) discriminated best from worst placekicks in all players. The three-cluster solution from SOM on these seven variables highlighted differences between players rather than best, worst, and typical attempts. Within-clusters, however, the best and worst placekicks tended to be represented in separate map regions. The seven variables identified using standardised effect sizes can be useful for group-level coaching of placekicking skills in absence of individual data, and translated in an applied setting using verbal and visual cues to promote overall placekicking performance. However, players’ idiosyncrasies formed the main SOM boundaries, indicating that optimising placekicking success would benefit from an individualised approach and numerous effective movement templates may exist.
Sketching social robots: Visualising futures of human–robot interaction through participatory imagination
(Design Research Society, 2026) Vanderschantz, Nicholas; Turner, Jessica Dawn; Konig, Jemma Lynette; Timpany, Claire; Siddika, Rafeea; Shakes, Nathan
In this paper, we explore sketching as a speculative and reflective practice for imagining social robots. Through a series of participatory design workshops, participants observed two prototype robots and then produced sketches and word maps envisioning possible appearances, behaviours, and social roles for robots in everyday life. Analysing the artefacts of these workshops reveals how non-expert human users perceive and imagine future robots in their worlds. We examine common themes of emotion, familiarity, discomfort, and relational values in the artefacts produced by the workshop participants. Our work highlights a way that sketching and written idea generation by non-designers can serve as a tool for thinking through affective, aesthetic, and relational possibilities in human-robot interaction. By situating sketching as a medium for speculative imagination rather than technical specification, our paper contributes to an emerging understanding of Sketching Futures as a relational, situated, and iterative process.