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The formation of free floating planets from massive self-gravitating discs with growing binary seeds
No full textOver the past 25 years, observations have uncovered a large population of freefloating planets (FFPs), whose origins remain debated. Massive FFPs (several Jupiter masses or more) may form via gravitational collapse of molecular clouds, similar to stars. Lower-mass FFPs likely originate in planetary systems and are later ejected through dynamical interactions. In this thesis, I show that disc fragmentation in young stellar binaries is an efficient source of Jupiter-like FFPs (JFFPs). In this model, disc fragmentation at tens to 100 au from the primary star produces gas giants, while fragmentation further out forms a more massive object that eventually evolves into a secondary star. I present 3D simulations of massive, self-gravitating discs with embedded Jupiter-mass planets and a secondary seed (5 – 50 MJ); chaotic migration leads to frequent planet–secondary interactions, imparting velocity kicks to the planets that can result in planet ejections. The ejection fraction increases steeply with the secondary-to-primary mass ratio, q, reaching 2/3 for qs ě 0.05. Compared to Core Accretion JFFPs, disc fragmentation JFFPs: (i) form earlier, and may be more abundant in young clusters, and (ii) are ejected at much lower velocities. This model is also expanded to include varying initial inclinations for the planets (0 – 90°), and masses (0.001 – 3 MJ), while keeping the initial secondary mass consistent throughout, at 25 MJ. The initial inclination of the planets does not appear to affect the ejection fraction, or the post-ejection velocities of FFPs. Interactions with the secondary can lead to ejections, regardless of planet mass – planets likely to be ejected are the ones that spend the most time in the vicinity of the secondary. Gravitationally unstable systems are therefore a promising mechanism for the production of FFPs.</p
Improving representation of African-ancestry populations in genetic association studies of lung function traits
No full textLung function is a key predictor of morbidity and mortality from diseases used in diagnosing and grading severity of chronic obstructive pulmonary disease (COPD). While genome-wide association studies (GWAS) have identified 1,020 loci associated with spirometric traits, these findings are based on largely European-ancestry populations. African-ancestry populations remain vastly underrepresented in GWAS, hindering equitable application of, and benefits from genomic medicine. This PhD investigates both genetic and non-genetic determinants of lung function in African populations, using data from the Africa Wits-INDEPTH Partnership for Genomic Studies (AWI-Gen) and other African-ancestry cohorts.Chapter 2 presents the generation of curated, high-quality spirometry phenotypes for 1,767 AWI-Gen participants, followed by a study of non-genetic predictors of lung function in the AWI-Gen population. Chapter 3 reports the first genome-wide association study of lung function traits conducted exclusively in individuals recruited from the African continent, and demonstrates the use of these data to calibrate polygenic risk scores for lung function in African populations. Chapter 4 delivers the largest GWAS meta-analysis of lung function in African-ancestry populations to date (N = 10,356), while Chapter 5 applies multiple variant-to-gene mapping approaches to describe biologically plausible effector genes for lung function.I identified 130 lung function sentinels at GWAS P<5x10-6 in the global meta-analysis and 102 sentinels in the AWI-Gen continental-specific GWAS, four of which reached genome-wide significance (p<5x10-8). Genes such as FBLN2, ADAM10, and KIF16B were strongly supported and converge on pathways central to epithelial integrity, immune regulation, and extracellular matrix remodelling that are central to lung function. This work provides the first African-specific lung function GWAS, the first application of African-ancestry specific pQTL data in lung function genetics, and improved calibration of African-specific risk scores for lung function.</p
In situ synchrotron radiography of graphite nodule evolution during solidification in ductile cast iron
No full textDuctile cast iron (DCI) is widely used in renewable-energy and transport applicationsbeca use it combines castability, strength, and fatigue resistance. Its mechanical properties are largely governed by the morphology and size distribution of graphite nodules; understanding their evolution during solidification is therefore critical for industrial optimisation. In situ synchrotron radiography was used to capture nodule evolution across remelting cycles. Combined with automated detection–tracking, this approach quantitatively resolves nucleation, flotation, growth, and degeneration. Inclusion dynamics were directly observed, revealing that shrinkage-driven convection strongly governs inclusion motion. The onset of convection coincides with primary nucleation and likely triggers it via local thermal and compositional changes. Graphite flotation occurs continuously throughout solidification: nodules grow rapidly during ascent and slow abruptly upon arrest by the dendritic network. Wide interdendritic channels enable prolonged flotation and lead to the formation of exceptionally large nodules. Primary spheroidal graphite (SG) nucleation shows a rapid initial growth phase followed by a distinct drop in rate. Its final size is strongly influenced by the local dendritic structure, resulting in large variability. In contrast, secondary SG nucleation is diffusion-driven and proceeds at roughly one-sixth the initial growth rate of primary events. This disparity likely reflects stronger undercooling, higher carbon supersaturation, and vigorous convection during early solidification. Across remelting cycles, as magnesium fades, compacted graphite (CG) becomes increasingly prevalent. A morphological transition is observed—from early interconnection-dominant forms to later protrusion-driven growth—accompanied by higher areal growth rates and increased final CG fractions. While the frequency of primary SG graphite nucleation remains largely unchanged, secondary SG nucleation undergoes a marked decline.</p
Constructing the Heimat: A Critical Discourse Analysis of Disability and Forced Displacement in the German Press (1990-2015).
No full textThis thesis examines representations of disabled and forcibly displaced people in the German press between 1990 and 2015 from a social constructionist perspective. It analyses the discourse surrounding these two groups, often portrayed as either included or excluded, vulnerable or threatening, and investigates how these dichotomies shape the German concept of national belonging via the historically and socially significant idea of Heimat.Rather than a comparative study, the research analyses the portrayal of these two groups according to a specific German notion of belonging to understand how discourses of vulnerability and threat contribute to the nation-building function of this concept.The analysis reveals how Heimat functions as a means of limiting agency and self-determination for both groups, constructing them, sometimes interchangeably, as either one discourse or the other.Grounded in corpus-assisted (critical) discourse studies (CADS), and complemented by the Discourse-Historical Approach (DHA), the thesis employs corpus linguistic tools and van Leeuwen's sociosemantic inventory of social actors (2008). Accordingly, it interrogates news articles that appeared in three ideologically divergent newspapers (Bild, Frankfurter Allgemeine Zeitung and Süddeutsche Zeitung) between 1990 and 2015. This methodology enables a critical investigation of the ideological function of language, revealing hidden structures via the interrogation of discursive strategies like presuppositions, metaphors, topoi, and collocations deployed in the German press.Approached from a Foucauldian perspective, this thesis, therefore, contributes to literature that conceives of Heimat as a discourse, that is, an ideological mechanism of control in the service of a distinctly German form of belonging. As a hegemonic discourse, the notion of Heimat constructs polarised oppositions such as threatening/vulnerable, which reveals the lens through which power operates in the German press. The research concludes that potent identity and nation-building infrastructure deploys at times seemingly-conflicting categories that ultimately serve the singular purpose of reinforcing the dominance of Heimat.</p
Impacts of global climate change on polar heritage: assessment of imperilled polar heritage sites
No full textDetermining how climate change will impact polar heritage sites during the next few decades is a daunting task subject to many variables. It can be difficult in these circumstances to know exactly where one should begin to act, and yet the results of inactivity are predictably dire. The methodological framework presented in this thesis exploits relationships which exist between site geography, geology, temperature, and materiality; all of which are strongly correlated with the likelihood and severity of climate change impacts. While these features of a site do not cause climate change impacts in and of themselves, they provide insights into the timescales at which impacts are likely to take place, and the resiliency of sites to accommodate those impacts when they occur. A key advantage of this approach is that by focusing on measurable site characteristics and features, a meaningful place to act emerges, even as multiple potential future scenarios are considered, and results are refined. This research explores the practice of polar heritage conservation in the context of a rapidly changing global climate. With a focus on historic sites related to the periods of exploration and exploitation corresponding to the 17th to early 20th centuries (i.e., post Norse expansion of the Arctic and pre-Cold War militarization of Antarctica and the Arctic), the thesis develops a novel approach to assessing the risks of climate change impacts on cultural heritage sites, the effectiveness of which derives from its accommodation of positive feedback loops.</p
Perceived Financial Scarcity Leads to Financial Avoidance: The Mediation of Financial Self-efficacy and Financial Risk Aversion
No full textWhile the extant literature suggests that financial scarcity is linked to the avoidance of financial activities, we explore whether and why this relationship persists even when such activities are beneficial for alleviating financial scarcity. By conducting seven studies, we show that the relationship persists even when the financial activities are beneficial for alleviating scarcity and remains after controlling for factors such as financial literacy and debt (Studies 1A and 1B). This relationship is further validated in a field setting (Study 2) and in experiments where perceived financial scarcity is manipulated (Studies 3 to 5B). Impaired financial self-efficacy and increased financial risk aversion mediate this effect (Study 4). Moreover, this effect is reversed when financial self-efficacy is enhanced (Study 5A) and attenuated when the perceived risk of financial activity is reduced (Study 5B). The implications for policy interventions, consumer coping strategies, and financial well-being are discussed.</p
Man is the measure of all things: Evaluability and overpackaging
No full textDespite the fact that overpackaging can signal better product protection and higher quality, it may also trigger perceptions of waste and diminish perceived value. With such a persistent tension, it remains unclear when and why overpackaging can be beneficial or harmful. To tackle this issue, this research leverages cue utilization theory and general evaluability theory to propose product evaluability as a boundary condition to explain consumer responses to overpackaging. A series of five studies, using a variety of operationalizations of evaluability and packaging, different research designs, and secondary data from both Eastern and Western cultural contexts, consistently show that consumers prefer overpackaging only when product evaluability is low, whereas they prefer non-overpackaging when product evaluability is high. Our research also reveals two asymmetric pathways through perceived value: when product evaluability is low, overpackaging increases purchase intention via boosting quality value, whereas when product evaluability is high, overpackaging decreases purchase intention via reducing price value. These findings reframe overpackaging from a universally wasteful practice to a context-dependent retail strategy, implying that packaging decisions should be matched to product evaluability rather than standardized across different product assortments.</p
PremPath scoping interviews
No full textThe PremPath study was funded by the National Institute for Health and Care Research Policy Research Programme (NIHR204242) between April 2023 and June 2025. The perinatal optimisation pathway brings together a number of evidence-based interventions to reduce the risk of neonatal death and associated preterm morbidities. This project was commissioned to examine how the pathway is working in practice. We aimed to explore how multiple clinical teams work together to make decisions about the optimisation and stabilisation of preterm infants and to explore the experiences of staff delivering the pathway, and parents and families receiving care. We took a qualitative approach: this resource comprises scoping interviews with 40 staff (Patient Safety Collaborative workstream leads and regional leaders) working in twelve of the fifteen regions in England. Tow of the interviews involved two members of staff.</p
Quality of life and multiple long-term conditions in Southeast Asia: a systematic review and meta-analysis.
No full textThis review systematically synthesised the evidence on quality of life measures and outcomes for people living with multiple long-term conditions in the Southeast Asia region. Results were analysed using a combination of methods, meta-analysis for studies where the same quality of life score was reported across three or more cohorts, and descriptive narrative synthesis. In total, 34 studies comprising 11,876 participants were included in the narrative synthesis and 14 of these were included in meta-analysis. The most common quality of life tools used included WHOQOL-BREF (n = 8) and EQ-5D-5L (n = 3) with pooled mean values of 70.47 (95% CI: 62.71 to 78.24) and 0.76 (95% CI: 0.67 to 0.84) respectively, indicating reduced but good quality of life. As healthcare systems adapt to the evolving challenges associated with multiple long-term conditions, understanding the tools and measures used to assess quality of life in different contexts becomes imperative to account for disease combinations and cultural nuances.</p
Rethinking control-IQ+ technology: Simple strategies for easy optimization
No full textControl-IQ+ is an automated insulin delivery (AID) algorithm approved for people with type 1 diabetes aged 2+ years and adults aged 18+ years with type 2 diabetes. While numerous publications support improved glycaemia and quality of life for people with diabetes, this practice paper is intended to encourage uptake for healthcare professionals (HCPs) who are less familiar with AID systems. This includes recommendations for initializing settings, as well as research and practice-based approaches to optimizing glycaemia with stronger settings (e.g., strong correction factor settings). In addition to automated insulin adjustments every 5 min, Control-IQ+ delivers a large Autobolus up to once per hour, which can improve glycaemia in people who have challenges with routine bolusing. Simple bolus strategies and tips and tricks also highlight how to make Control-IQ+ easy to use for HCPs and the person with diabetes.</p