Recent advances in principal component analysis for directional data

The high dimensionality of the input data can pose multiple problems when implementing statistical techniques. The presence of many dimensions in the data can lead to challenges in visualising the data, higher computational demands, and a higher probability of over-fitting or under-fitting in modelling. Furthermore, the curse of dimensionality contributes to these issues by stating that the necessary number of observations for accurate modelling increases exponentially as the number of dimensions increases. Dimension reduction tools help overcome this challenge. Principal Component Analysis (PCA) is the most widely used technique, intensively studied in classical linear spaces. However, in applied sciences such as biology, bioinformatics, astronomy and geology, there are many instances in which the data’s support are non-Euclidean spaces. In fact, the available data often include elements of Riemannian manifolds such as the unit circle, torus, sphere, and their extensions. Therefore, the terms “manifold-valued” or “directional” data are used in the literature for these situations. When dealing with directional data, the linear nature of PCA might pose a challenge to achieve accurate data reduction. This paper therefore reviews and investigates the methodological aspects of PCA on directional data and their practical applications

Clothing as microbial fomites in an equine veterinary hospital—Could interventions reduce nosocomial infection risk?

Background:Clothing in human medical environments has been shown to be contaminated with micro-organisms. There is little work in this area in the veterinary environment and none in equine veterinary environments.Objectives:To characterise microbial contamination of veterinary clothing throughout a work shift in an equine hospital. The pattern could help determine whether an intervention could reduce contamination.Study Design:Cross-sectional, observational pilot study of staff at B&W Equine Hospital in February 2023. The study used convenience sampling of staff clothing.Methods:Ninety-two swabs from the clothing of 46 staff were taken at three time points (start of the day [AM], lunch and end of the day [PM]). Samples were cultured with colony-forming units (CFUs) per swab, and the genus of the microbe present was identified. Statistical analysis was performed.Results:Five genera of microbes were identified on clothing. Veterinarians became significantly more contaminated from AM to PM (p = 0.034). All groups of staff arrived at work already contaminated. All AM samples from staff had Streptococcus spp. present. Rhodococcus spp. were not present on nonclinical staff.Main Limitations:Small sample size not representative of all equine hospitals. Hospital-based not representative of ambulatory practices. Volunteer bias and the use of a nonprobability sampling method. Genetic sequencing not performed to determine the species of the microbe present.Conclusion:This study found that veterinarians became significantly more contaminated throughout the day. This suggests that a simple intervention such as changing outer layers of clothing at lunchtime could reduce contamination levels. All groups were contaminated on arrival to work, suggesting that in-house laundering to regulate the cleanliness of uniforms could reduce microbial contamination. To reach a full conclusion on the diversity of contamination, further research, including full identification of microbes, is required

Arthur in the Mountains:The Multivalency of Mont-Saint-Michel and the St Gotthard Pass in the Alliterative Morte Arthure

Very little has been written on the topic of mountains in medieval English literature. For the most part, there is a tendency to consider them as incidental background features of a work, serving as part of a broader metaphorical conceit, or as hostile and dangerous spaces, landscapes of trial or necessary obstacles to overcome in the course of travel. Scholarship on the medieval environment has developed significantly in recent decades alongside a broader interest in environmental and ecological humanities. However, it is only quite recently that work relating to the study of premodern and early modern mountains has begun to challenge the widely-held belief that the eighteenth century marks a clear dividing line in the way that authors, artists, and poets were defining and conceptualising mountain landscapes. Focusing on the Alliterative Morte Arthure, this article argues that our understanding of the value of mountain settings in works of Middle English literature has been simplistic. As growing scholarly interest in the medieval environment continues to broaden our awareness of the actual landscapes and ecologies of the Middle Ages, literary scholars should simultaneously pay further attention to mountains as part of the medieval imagination. Focusing in particular on two moments from the poem - Arthur’s encounter with the giant on Mont-Saint-Michel and his crossing of the Alps via the St Gotthard pass - this article argues that there is a richness to the mountains of the Alliterative Morte that goes far beyond the clichés and overused motifs that have so far been recognised as the medieval period’s foremost contribution to mountain literature. They are at once alien and familiar, dangerous and bucolic, literal and figurative. Far from being background features of the poem, they form a consistent and integral part of the poet’s cultivation of meaning throughout the text

Ageing-dependent, multi-hazard fragility of monopile-supported offshore wind turbines

This paper presents time-dependent multi-hazard fragility functions for a monopile-supported 5 MW offshore wind turbine (OWT) under combined stochastic wind, wave and seismic loads. Ageing is considered by explicitly modelling two major deterioration phenomena: support structure zonal corrosion and monopile foundation scouring. A Latin Hypercube sampled, cloud-based, dual-intensity-measure (IM) fragility assessment framework is employed to produce multi-hazard fragility surfaces at nine evenly separated instants (0–40 years). Various model uncertainties were accounted for via a pre-defined multivariate probabilistic distribution. Failure probabilities at different ages were derived using Gaussian Process Regression (GPR) for selected Engineering Demand Parameters (EDPs), where the full range of operational inflow wind speeds (3–25 m/s) was considered. Over time, the modal characteristics of the soil-foundation-structure system deviate from its original state. The probability of an OWT exceeding the ultimate limit state (ULS) criterion when subjected to a design-level combination of wind, wave and earthquake loads is not just nonnegligible but can increase considerably owing to ageing: by 66 % after 10 years of operation and 100 % after a typical 25-year design life. The results indicate the importance of multi-hazard coupling and provide a robust framework for assessing time-evolving fragility under joint earthquake-wind-wave loading

EAL scholars' experiences of writing for publication in English:A meta-ethnographic synthesis of qualitative evidence

This meta-ethnographic synthesis integrates qualitative findings from 26 empirical studies exploring English-as-an-additional-language (EAL) scholars' experiences of writing for publication in English (WPE). It identified three key elements shaping these experiences, including the motivation behind WPE, encompassing both personal aspirations and institutional pressures; insecurity about WPE, stemming from uneven institutional support, biased journal gatekeeping, and professional and linguistic self-doubt; and coping strategies for WPE, including seeking support from multiple sources, metacognitive reflection, and alternative, sometimes critical, approaches. Together, these findings reveal how systemic constraints can exacerbate scholars' anxieties, while adaptive strategies underscore EAL researchers’ resilience. The study contributes a more integrative conceptual framework linking these aspects to illustrate the complexities of WPE. It concludes by highlighting the need for institutional reforms, broader recognition of diverse publication outputs, and inclusive editorial policies

Rapidity and multiplicity dependence of charged-particle flow in pPb collisions at √^sNN = 8.16 TeV

The elliptic and triangular flow of charged particles are measured using twoparticle angular correlations in pPb collisions in the pseudorapidity range 2.0 < |η| < 4.8. The data sample was collected by the LHCb experiment in 2016 at a centre-of-mass energy per nucleon pair of √sNN = 8.16 TeV, containing in total approximately 1.5 billion collision events. Non-flow contributions are obtained in low-multiplicity collisions and subtracted to extract the flow harmonics. The results are presented as a function of event multiplicity and hadron transverse momentum. Comparisons with a full (3+1)D dynamic model indicate that it overestimates the measured elliptic flow. A comparison between the forward and backward regions reveals no significant differences in flow parameters, suggesting that final-state effects may dominate over initial-state effects in the origin of flow in small systems

Experimental study of the aeroacoustic behavior of a pitching NACA65-410 airfoil

This study experimentally investigates a NACA65-410 cambered airfoil undergoing oscillating pitching motions at a chord-based Reynolds number of Re$_c=4.2\times 10^5$. Two reduced frequencies, k_r=0.023 and k_r=0.052, were tested. Results show that increasing the pitching amplitude and frequency leads to higher far-field noise. Surface pressure fluctuations are generally comparable or higher in the pitching cases compared to static case, except in deep stall where the static cases showed stronger fluctuations. Phase-averaged surface pressure spectrograms reveal significant differences between dynamic and static cases, with four distinct flow regimes emerging around stall onset and flow reattachment. These regimes are sensitive to k_r, mean angle of attack, and pitching amplitude, while maintaining consistent characteristics. Asymmetric behavior in surface pressure fluctuations and overall sound pressure level is observed, particularly at higher k_r. Coherence maps along the chordwise direction reveal an increase in coherence at higher angles of attack, which further intensifies as flow separates from the airfoil, where the convecting structures to the downstream dominate the flow. These findings are crucial for advancing the design and noise mitigation strategies of airfoils in applications such as rotorcraft, wind turbines, and unmanned aerial vehicles, where dynamic stall and associated acoustic emissions impact performance and environmental compliance

Social bonds decrease epigenetic age in male bottlenose dolphins

Ageing is a universal process characterised by the deterioration of functional traits over an individual’s lifespan. Differing degrees of age-related decline between individuals of the same chronological age suggest varying rates of ageing. Identifying factors influencing these inter-individual differences in ‘biological age’ is central to understanding ageing. In social mammals, social variables affect lifespan and are therefore likely to affect biological age. In Shark Bay, Western Australia, male bottlenose dolphins forge persisting intrasexual social bonds that affect their reproductive success and, therefore, their evolutionary fitness. We investigate the relationship between cumulative social bond strength, group size, and biological age of individual male dolphins in this population. Biological age is inferred using a species-specific epigenetic clock, the current gold standard for such an inference. We find a significant negative effect of cumulative social bond strength and a significant positive effect of group size. This implies that the negative effect of social bonds on epigenetic age cannot be attributed solely to group-living, but to benefits of the social bonds themselves. As established in humans, we find that the strength of social relationships affects epigenetic age, indicating that sociality may be linked to biological ageing more broadly across social mammals

Examining the effects of simulated Low Earth Orbit on the viscoelasticity and strain behaviour of deployable polybenzoxazine nanocomposites

Thin polybenzoxazine (PBZ) nanocomposite laminates containing polyhedral oligomeric silsesquioxane (POSS, 5 and 10 wt%) and reinforced with carbon and Kevlar® fabrics are prepared on a large (350 mm x 290 mm x 0.4 ± 0.05 mm) scale. Composite specimens are exposed separately to progressive amounts of atomic oxygen (AO), gamma radiation, and vacuum ultraviolet radiation (VUV) to simulate up to 18 months of exposure in low Earth orbit, before being analysed by a range of techniques to examine the thermal, thermo-mechanical, and surface characteristics. The inclusion of POSS leads to the development of a protective silica rich layer (1-2 μm) in response to AO and significantly reduces the surface roughness compared with the same blend in the absence of POSS, while the Tg of the blend containing 10 wt% POSS is raised by up to 26°C over 18 months of simulated exposure. In contrast, gamma radiation has little effect on the Tg (increase of 2.5°C over the same exposure period) and effects less roughening, particularly where POSS is present. Exposure to VUV results in a loss in reflectance properties, but this is reduced as the POSS content is increased