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This article presents a new flow feature observed behind a rectangular wing in water: the breakdown of the wing-tip vortex induced by the temporary injection of air into the vortex core downstream of the wing. For certain combinations of Reynolds number and angle of attack, a stationary air bubble is trapped in the core at some distance from the wing and can persist for several minutes after the injection is stopped. For other parameter values, the bubble drifts downstream or upstream until it reaches the wing, or it disintegrates immediately. Measurements of the vortex properties and bubble characteristics are presented and discussed. The breakdown behaviour, which is unrelated to cavitation, is found to depend mainly on the tip vortex circulation and on the axial flow component in the vortex core. Only configurations with a velocity excess, with respect to the free stream, at high angle of attack, allow the formation of a breakdown bubble.
We investigate the onset of thermosolutal instabilities in a layer of moderately dense nanoparticle suspension cooled at the substrate in the presence of interfacial nanoparticle kinetics (adsorption and desorption) at the deformable interface. Gravity and the Soret effects are taken into account. A mathematical model with nanoparticle concentration-dependent thermophysical properties of the nanofluid is formulated. The surface tension is assumed to be a linear function of the temperature; however, the equation of state displays non-monotonicity with nanoparticle concentration due to nanoparticle interfacial energetics. We carry out the linear stability analysis of the quiescent base state using normal modes and the obtained eigenvalue problem is solved numerically. The monotonic short-wave solutocapillary instability is found and analysed for different parameter sets. The limiting case of insoluble interfacial nanoparticle concentration is also investigated. Notably, we identify the onset of the monotonic short-wave thermocapillary instability owing to a strong coupling between the perturbations of interfacial nanoparticle concentration and temperature via the particle concentration-dependent thermal conductivity in general, and in particular, near the interface. The combined thermo-solutocapillary instability is also investigated. Finally, the simplified toy problem is formulated and solved analytically to demonstrate the role of thermal conductivity stratification and interfacial kinetics.
This study examined emotional interference and facilitation in cognitive processing among heritage bilingual and monolingual young adults across six tasks varying in emotional and linguistic demands. Results showed that bilinguals often exhibited comparable or more efficient processing than monolinguals in more demanding conditions (i.e., nonword rejection, high-load working memory tasks). Emotional valence effects were task-dependent and rarely differed across language groups, likely reflecting bilinguals’ dominance in English. Moreover, heritage bilingual performance was shaped by both English and Spanish language proficiency, as well as the age of second-language acquisition (AoA). Cognitive cost and valence effects varied by task, highlighting the interaction between task demands and bilingual language background. Findings emphasize the importance of individual bilingual experiences and task context in understanding cognitive and emotional processing, suggesting that group differences are not uniform but depend on nuanced language and task factors.
Chapter 4 examines communicative settings where the use of machine translation is particularly likely to involve high levels of risk. The chapter looks at guidelines about machine translation use and at the issue of consent. Two types of consent are examined, namely using machine translation to seek some type of consent, and consent that concerns whether the use of machine translation itself is consensual. The chapter then explores some of the direct reasons why machine translation is used in high-risk scenarios. These reasons include urgency, service user preferences and unreliable human language services. The project’s participating professionals were not short of stories to tell about human interpreters who had not turned up for appointments or telephone interpreting connections that frequently crashed. Incidents of this nature are considered within a broader context where limited resources and outsourced human language services normalise the reliance on machine translation in ways that increase risks and affect standards of care.
In the practice of archaeological research in Peru, a set of economic, political, and ethical contradictions can be recognized in the relationships between archaeologists, excavation technicians, and other groups. It has been observed that our social relationships in fieldwork and other archaeological practice spaces reproduce the principles of the free market, individual competition, and labor exploitation. However, a medium-term archaeological project, the Chicama Archaeological Program (PRACH), has been established on the northern coast of Peru, confronting those contradictions to transform socioeconomic relationships in the discipline. Over time, crew members and participants in this program have transformed their ways of being, transcending the conventional boundaries of mere workers. Despite the pervasive influence of the laws of the market on our social fabric, a conscious political stance has emerged as a counterforce, aiming to overcome the alienating effects of neoliberalism. Thus, our crew prioritizes cooperation, solidarity, and care over competition, individualism, selfishness, and immediate and utilitarian relationships. A host of challenges must be confronted, but the motivation for this effort lies in adopting an alternative, novel, and conscious approach to the inequalities generated by conventional forms of interpersonal interaction, especially in our archaeological practice.
The Youth Physical Activity Promotion Model (Welk, 1999) has provided a specific framework to understand children’s and adolescents’ physical activity behavior. The objectives were (1) to analyze whether the data collected in Chilean and Spanish adolescents fit the proposed model and (2) to analyze the countries’ differences (Spain vs. Chile) in enabling, predisposing, and reinforcing as well as the demographic factors that influence physical activity. The sample comprised 2318 adolescents from Spain (Mage = 14.5, SD = 1.36; 51.9% females) and 734 from Chile (Mage = 14.7, SD = 1.47; 54.2% females). The variables measured were reinforcing factors: fathers’, mothers’, friends’, and Physical Education teachers’ social support; predisposing factors: perceived competence and enjoyment; enabling factor: body mass index; and demographic factor: country of origin. Results showed that the youth physical activity promotion model was supported by the data collected from Spanish and Chilean adolescents. Nevertheless, differences in the model were observed when comparing the Spanish and Chilean populations. Perceived competence and the father’s social support predict Chilean adolescents’ physical activity. In Spain, perceived competence and the mother’s social support predict adolescents’ physical activity. Therefore, the country of origin is a key factor in understanding physical activity because education and family culture may influence physical activity in different ways.
By 2022, social media platforms had become more prominent access points to news than traditional news media platforms. Although news media also draw benefits from online platforms, they find themselves in an increasingly asymmetric relationship that appears to harm journalists and new media’s ability to generate revenues online. Remedying the uneven playing field between big tech and news media has been a recurring ambition of European media policy. In the context of literature on corporate political activity, this chapter investigates how three big tech companies, Alphabet, Meta and Microsoft, have positioned themselves in relation to EU policymaking that aims to strengthen the rights of journalists, news media and press publishers online. The chapter argues that while these big tech companies primarily seek to preserve their own business models and reputations, the media policy domain also reveals a split in their lobby narratives. Due to lower exposure to reforms in digital media policy, Microsoft has been less opposed to, and in fact has campaigned for, stronger protection for news media against digital platforms.
Focusing on case studies of Shrewsbury, Chester, York, Coventry, and Bristol, this article analyzes how the concept of the “historic town” emerged in the first half of the nineteenth century. Traditionally a town’s historic identity had been understood in a legal and institutional sense. By the end of the eighteenth century, however, the use of the term “ancient” or “historic” to describe a town had become less a claim to long-standing privileges and traditional importance than an indication of a particular appearance and atmosphere, redolent of an era that was increasingly referred to as “the olden time.” A historic town offered the promise of a certain kind of historical experience and ambience that could be strategically exploited in order to attract visitors, and their custom, in greater numbers. The “invention” of the historic town was most obviously a response to the rapid changes consequent upon urbanization. But we need also to consider other factors, including changing attitudes toward the past and the broader consumption of history; developments in architectural history, particularly a new appreciation for the vernacular domestic architecture of the early modern period; and the rise of domestic tourism, facilitated by the advent of railway travel. Finally, the invention of the historic town is also a story about the early origins of heritage and the emergence of a preservationist ethos.
This book concludes with a summary of key types of machine translation use discussed in the project. The conclusion outlines ethical principles of multilingual AI use including the potential or intended legal value of a message, the stability of the information and its potential to be reused, and the need for any uses of machine translation to be transparent and as far as possible consensual and cybersecure. The conclusion also examines some of the challenges posed by the broader project. It offers a reflection on the question of accountability and on the difficulties of living well with technology in environments that elevate cost efficiency above other values.
As generative artificial intelligence chatbots become embedded in everyday life, concerns about their psychological risks are growing. Emerging reports describe cases of artificial intelligence-induced or -associated psychosis (hereafter artificial intelligence (AI) psychosis) in which intensive chatbot use is associated with delusional thinking patterns. This paper proposes a provisional mechanism wherein baseline user vulnerabilities and engagement patterns interact with generative artificial intelligence characteristics, such as sycophancy and hallucination, contributing to delusional ideation. It subsequently outlines clinical, design and regulatory strategies that may help mitigate risks.
This chapter examines the dynamics of European Union (EU) media regulation created in response to digital communication challenges that affect media freedom and pluralism. In the context of the trend of outsourcing digital regulation to global private actors, the chapter focuses on the redistribution of media regulation competencies between Member States and the EU as an implication of the European Media Freedom Act. Particular attention is placed on the problems of enforcement and compliance; discrepancies in how supranational regulations are interpreted, together with differences in resources available to national regulators, could prevent the intended outcomes. In conclusion, the chapter discusses the democratic legitimacy of EU media regulation, pointing to the widening gap between public deliberations and regulatory decisions in the transnational sphere.
What is the physics behind getting a spacecraft to the nearest stars? What science can it do when it gets there? How can it send back data over enormous distances? Drawing on established physics, Coryn Bailer-Jones explores the various challenges of getting an uncrewed spacecraft to a nearby star within a human lifetime. In addition to propulsion methods such as nuclear rockets and laser sails, this book examines critical issues such as navigation, communication, and the interstellar medium. Starting from fundamental concepts, readers will learn how a broad spectrum of physics – ranging from relativity to optics, and thermodynamics to astronomy – can be applied to address this demanding problem. Assuming some familiarity with basic physics, this volume is a comprehensive and self-contained introduction to interstellar travel, and an indispensable guide for studying the literature on deep space exploration. This title is also available as open access on Cambridge Core.
We investigate the broadband turbulent dynamics of attached and separated flows over a Gaussian bump, focusing on the origin of low-frequency coherent structures. The analysis combines time-resolved experimental measurements with physics-based linear models, using mean fields previously assimilated from the same dataset as base flows. Spectral proper orthogonal decomposition reveals a coherent dynamics in low- and medium-frequency regimes for both flows, with the low-frequency dynamics being substantially stronger in the separated case. In the separated flow, this dynamics is linked to a three-dimensional zero-frequency modal instability that generates large-scale streamwise-elongated structures downstream of the bump. A standing-wave model based on resolvent modes, incorporating finite-span effects, reproduces the experimentally observed spanwise structure of the dynamics and highlights the limitations of simulations with small spanwise extent and periodic boundary conditions. In the attached flow, similar low-frequency structures are identified. These are weaker, do not form a prominent standing-wave pattern and cannot be definitively classified as either modal or non-modal. The three-dimensional zero-frequency instability and finite-span standing-wave dynamics are identified as the main drivers of low-frequency coherent structures in the separated flow. They offer an explanation for persistent discrepancies between simulations and experiments on the Gaussian bump, and provide guidance on spanwise domain size and boundary conditions for future simulations.
In collisionless astrophysical plasmas, turbulence mediates the partitioning of free energy among cascade channels, and its dissipation into ion and electron heat. The resulting ion heating is often anisotropic, with ions observed to be preferentially heated perpendicular to the local magnetic field; understanding the mechanisms responsible for this heating is a key step in understanding the evolution of such plasmas. In this paper, we use the framework of quasi-linear theory to compute analytically the heating rates of ions interacting with turbulent, large-scale Alfvénic fluctuations. We show how the imbalance of the turbulence (the difference in energies between Alfvénic fluctuations travelling parallel and antiparallel to the magnetic field) modifies the spatiotemporal spectrum of these fluctuations, allowing the heating mechanism to smoothly transition between stochastic heating in balanced turbulence and cyclotron-resonant heating in imbalanced turbulence. The resultant heating rate is found to have a general form regardless of the level of imbalance, exhibiting a suppression related to the conservation of the ions’ magnetic moment at small turbulent amplitudes and recovering previous empirical results in a formal calculation. The results of this work help to consolidate our qualitative understanding of ion heating within astrophysical plasmas, as well as yielding specific quantitative predictions to analyse simulations and observations.
Negative symptoms are a core feature of psychosis and a strong predictor of functional outcome, yet they remain difficult to assess due to conceptual and methodological challenges. Although abnormalities in emotional expressivity and emotional reactivity are documented in individuals at clinical high-risk (CHR) for psychosis, these domains are typically examined independently, and their relationship remains unclear.
Methods
Facial expressions were quantified using automated facial analysis (FaceReader) during clinical interviews in 101 CHR individuals and 41 healthy controls (HCs). Emotional reactivity was assessed using the International Affective Picture System (IAPS). Principal component analyses were conducted on facial expression and emotional reactivity variables within the CHR group. Associations with negative symptom domains, positive symptoms, and social functioning were examined using correlational and two-step regression analyses.
Results
CHR participants showed greater disgust expression than HCs (g = 0.40, uncorrected p = .0025, FDR-corrected p = .023). Facial expression and emotional reactivity components showed minimal associations (p > .20). Reduced high-arousal facial expressions were associated with greater emotional expressivity deficits (r = −.22, p = .027), whereas greater happy facial expression was associated with more motivation and pleasure impairment (r = .21, p = .044). Happy facial expression explained additional variance in motivation symptoms beyond emotional reactivity (ΔR2 = .089, p = .008).
Conclusions
Automated facial expression captured variance in some negative symptom domains that was largely independent of emotional reactivity. These findings support the use of multimodal, objective assessments to improve characterization of negative symptoms in psychosis risk.