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

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

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

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

Big data as a propeller for the tourism sector:Present opportunities and Future Perspectives

Although Big Data have opened a whole new world of opportunities for scientists, managers, businesses, and governments towards achieving increased effectiveness in decision-making processes (Morabito, 2015; Phillips-Wren and Hoskisson, 2015). Still there are various challenges that need to be addressed, such as the use of Big Data in achieving effective systems responses, as well as dealing with individual and societal aspects of Big Data-related technological advancements. Key issues have already started being raised among scholars, i.e. the potential of Big Data to effectively contribute to decision-making, the conjunction of Big Data with the Internet of Things, as well as various concerns about value creation, privacy, and e-Surveillance (Wong et al., 2023). The current chapter discusses these vital issues and offers some insights for the future

Insider climate activism – slowing down or speeding up to decarbonize?

This chapter discusses climate activism in relation to speed, to explore two emerging polarized forms of “insider activism”, conceptualised as movements pursued in professional contexts. Both movements respond to the expressed “climate emergency”, the first by propagating for a Fast movement and the second for a Slow movement. By first presenting a spectrum of velocities that have emerged in response to the climate emergency, this chapter replays these temporal responses in two fictional polarizations of insider climate activism. The first illustration portrays employee activism within a CO2 polluting corporation, to investigate how Fast movements can develop within business. The second illustration, in contrast, portrays insider activism performed by public officials who work for a regional office, to explore how Slow movements can prosper within public organizations. This method produces a polarization, facilitating a reflective comparison of how activism pursued at work can take different transformative paces, sometimes successfully aligning with other organisational rhythms and professional practices. While very diverse activist movements, slow as well as fast, could prosper within both the private and public sectors, these two polarized fictional examples provide insights into the largely unexplored desynchronized velocities that exist in climate activism

A Signal Detection Theory Meta-Analysis of Psychological Inoculation Against Misinformation

The spread of harmful misinformation poses a growing global threat, undermining trust in science, public health, and democracy. Psychological inoculation (i.e. “prebunking”) offers a promising approach to help people distinguish credible from manipulative content. We re-analyzed 33 inoculation experiments (combined N = 37,025) using Signal Detection Theory within a hierarchical Bayesian framework. Results show that both gamified and video-based interventions consistently improve discrimination between reliable and unreliable news, without increasing response bias—that is, participants did not become more uniformly skeptical or credulous. Our findings highlight the effectiveness of psychological inoculation in enhancing discrimination while avoiding unintended side effects on trust in credible news, offering robust support for its use as a scalable misinformation intervention

ACTS-3D:Advanced Continuous Tow Shearing for manufacturing of defect-free 3D complex composite parts

Continuous Tow Shearing (CTS) is a novel fibre steering process developed to overcome the inherent limitations of Automatic Fibre Placement (AFP), which relies on in-plane bending deformation of the tow in fibre steering process. Unlike AFP, CTS utilises in-plane shear deformation of the tow, and it has proven effective in eliminating fibre steering-induced defects on doubly-curved surfaces. However, challenges remain with more complex layups that cannot be perfectly tessellated using finite-width tows. This work introduces an advanced CTS process for three-dimensional complex geometries (ACTS-3D), incorporating a novel path planning and head control algorithm, along with an on-the-fly tow-width control (TWiC) mechanism. The path planning algorithm tessellates the surface using an improved pin-jointed strip (PJS) model that discretises the geometry of the individual variable-width tow. The local orientations of the CTS head, its nip points, and the local tow widths along the layup path are computed based on the spatial arrangements and lengths of the tow width elements within the PJS. To validate the feasibility of ACTS-3D process, a CTS prototype head with an integrated TWiC device was mounted on an industrial robot, producing a multi-layered fibre-steered preform on a doubly curved tool surface. Visual inspection and laser surface scans of the preform confirmed the potential of ACTS-3D for defect-free manufacturing of fibre-steered composite parts with complex geometries, by synchronously utilising the new head control and tow-width control