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The assessment and management of challenging behaviours following Acquired Brain Injury: A mixed methods review and cross-cultural study
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Bayesian inference, machine learning in Cardiac Mechanics for real-time clinical decision support
No full textThis thesis develops a Bayesian computational framework for parameter estimation and uncertainty quantification in ventricular biomechanics, based on a Gaussian-process (GP) emulator to accelerate finite-element simulations. First, a Kronecker product-structured GP surrogate model is constructed to generate a robust and computationally efficient map from input space to output space. Here, the input space is the combination of material parameters with a low-dimensional, PCA-based geometric representation of the left ventricle. The output space represents the diastolic inflation of the left ventricle, characterized by ventricular volume–time series. This approach exploits the fact that a tensor-product decomposition of the covariance matrix reduces the cost of covariance-matrix inversion by several orders of magnitude. Next, the emulator is embedded within a Markov-chain Monte Carlo sampling scheme conditional on in vivo MRI–derived ventricular volume data, yielding full posterior distributions of the myocardium material parameters and revealing how the number of measurement time points affects parameter identifiability and posterior uncertainty. To further constrain highly nonlinear, large-strain behaviour, ex vivo pressure–volume (Klotz) curve data are incorporated as complementary information, enabling principled fusion of multi-source measurements. Finally, the approach is applied to patients with hypertrophic cardiomyopathy, where individualized ventricular geometries are reconstructed via PCA, and the GP–MCMC pipeline delivers parameter posterior distributions and stiffness–strain curves for the respective subjects. The resulting workflow maintains high fidelity while reducing per-sample evaluation time from minutes to milliseconds, laying the groundwork for real-time clinical decision support
The Stone Mothers: magical realism and the physical manifestation of grief
No full textThe Stone Mothers: Magical Realism and the Physical Manifestation of Grief is a thesis in two parts. The first is a complete novel, The Stone Mothers, and the second is a creative non-fiction essay. Both developed from practice as research into the question ‘why women turn to stone.’
Female petrification occurs when women are silenced, and their rhetoric has become redundant. Whilst research for the critical element of this thesis covers women such as the Shakespearean Hermione, and Niobe, the novel addresses the contemporary silencing of women who have experienced the trauma of miscarriage.
When read in tandem, the works seek to address how magical realism functions and why it is vital in terms of representing trauma, specifically grief through perinatal loss, infertility, and miscarriage. Via the experimental form of The Fountain Ghost, the potentially reductive practice of academic self-erasure is called into question. Both elements of the thesis explore how we present ourselves, truth, and autobiography in our writing, and what I think of as fictive truth – an honest and authentic account that might use elements of fiction to enhance and clarify its position.
The rationality created by this dual reading was created through practice as research and explores petrification, transformation, and how and when we turn to stone
Factors influencing repeated non-utilized healthcare appointments from patients’ and healthcare providers’ perspectives in a Saudi Arabian hospital Outpatient Department: A qualitative study
Get PDFIn healthcare settings, multiple non-utilized appointments generate resource waste, longer wait times, and negative patient outcomes. Multiple non-utilized appointments are associated with poorer health, higher hospitalization rates, and premature mortality. Despite research in Western healthcare systems, there remains a significant knowledge gap regarding multiple non-utilized appointments in Gulf Cooperation Council (GCC) countries particularly in Saudi Arabia. Even though the issue is serious, we still do not know much about the reasons behind multiple non-utilized appointments in Saudi Arabia’s healthcare system and effective strategies to address this problem.
This thesis set out to address that gap, by examining multiple non-utilized appointments globally before narrowing its focus to the Saudi context. The aim was to identify the factors that contribute to multiple non utilized appointments from the perspectives of patients and healthcare providers and then examine what needs to be done to provide solutions. To achieve this, a two-phase qualitative research design was employed. The first study involved a systematic review of the global literature which included five qualitative studies from diverse healthcare systems. The second study was conducted in a Saudi Arabian hospital outpatient department. Twenty patients and twenty healthcare providers from different outpatient clinics were interviewed. Reflexive thematic analysis was conducted, with findings subsequently interpreted through Levesque’s healthcare access framework to understand the causes and potential interventions to the problem of multiple non-utilized appointments.
The results were that multiple non-utilization is not a matter of patient irresponsibility. Instead, it reflects a complex interplay between systemic inefficiencies and patient circumstances. Barriers were identified by using Levesque’s conceptual framework across four access dimensions: approachability (fear and anxiety, language barriers, technological challenges with digital systems, communication inefficiencies, administrative problems), acceptability (cultural mismatches, lack of empathy, unauthorized walk-in accommodations undermining scheduled appointments, privacy concerns for mental health), availability and accommodation (long waiting times, inflexible scheduling, overbooked clinics, staff shortages, geographical barriers for rural patients, problematic health apps) and appropriateness (provider-patient relationship issues, inconsistent records, frequent provider changes, structural barriers in booking systems). While some transportation cost issues found, affordability was not a primary barrier theme. These barriers corresponded with compromised patient abilities to perceive, seek, reach, and engage with healthcare services. Although some existing interventions showed promise many did not fully align with patient needs. The study recommends interventions targeting Levesque framework dimensions through enhanced healthcare delivery systems, improved patient access and engagement, and culturally sensitive service delivery.
This thesis contributes to the existing literature by clarifying the confusing terminology related to non-utilized appointments and demonstrating using Levesque’s framework that these non-utilized appointments are evidence of deeper issues. In addition, the results of this thesis found that the influence of male guardianship on women’s access to healthcare and the confusion caused by using both the Hijri and Gregorian calendars are two examples of the unique cultural factors that affect appointments utilization in Saudi Arabia. Moreover, the results revealed that although digital health tools intended to improve access can actually pose barriers particularly for older patients and patients with limited technological literacy underscoring the importance of designing culturally and contextually appropriate technologies. Lastly, the analysis revealed a gap between the demands of patients and the interventions that are now in place, providing important information for creating more efficient interventions to reduce non-utilized appointments.
Interventions aimed only at reducing service-level inefficiencies must give opportunities for approaches that are more open to the needs, backgrounds, and lived experiences of different patient groups
Integrated perspectives on macroeconomic dynamics: time series disaggregation, financial shock transmission, output clusters and monetary policy communication complexity
Get PDFThe absence of high frequency economic data and granular information has historically tended to limit the depth of evidence-based research inquiries in the literature aimed at understanding macroeconomic relationships. This thesis takes an empirical approach to address these gaps by, first, advancing an alternative simple data-driven method for generating high frequency and “flash” estimates for macroeconomic analysis. Second, it departs from the literature by determining linguistic complexity per-topic and showing how overall document complexity can obscure the specific topical elements whose linguistic complexity influence financial market movements. The thesis consists of three main parts:
The first chapter addresses the challenge of converting low frequency time series into high frequency time series. Traditionally, when high frequency data is needed but unavailable, researchers have heavily relied on simple regression-based temporal disaggregation methods to transform low frequency data into higher-frequency estimates. However, these methods face significant limitations - they typically utilise a small number of covariates due to multicollinearity issues and are more suited for explaining statistical relationships than predicting economic outcomes. To address these shortcomings, this study introduces a high dimensional time series disaggregation approach based on Partial Least Squares (PLS) regression. Using U.S. data from the FRED database, comparative analyses of temporal disaggregation and nowcasting demonstrate that the proposed data-driven approach offers an advantage over traditional methods for generating desired high frequency time series and prediction of flash estimates.
The second chapter constructs missing state-level historical quarterly output growth data for the U.S. by leveraging existing annual output growth data by state, state-specific economic indicators, and the PLS method proposed in the preceding chapter. The estimated historical dataset is used in two subsequent analyses: first, the data is used to analyse the differential impact of an aggregate financial shock on state-level real economic activity; and second, it is used to investigate the interconnectedness of economic activity across U.S. states. The study results confirm differentiated response of state-specific out-put growth to an aggregate financial shock and that the U.S economy forms three main economic clusters with two small ones. These applications offer valuable insights into the differentiated impact of an aggregate financial shock and the dynamics of economic activity connectedness among the individual states. The results highlight weaknesses of one-size-fits-all monetary or fiscal policy in favour of state-specific policy responses.
In the final chapter, I provide a novel approach that determines complexity of specific contents of the monetary policy statements. I examine the response of the 10-year government bond liquidity to the linguistic complexity of the overall central bank communication, and that of the individual topics. In order to generate evidence, I study the market liquidity outcomes when the level of linguistic complexity of monetary policy statements is low and when it is high for the Reserve Bank of South Africa (SARB). Descriptive results show that, first, liquidity is generally low on announcement days relative to the 10-day control day. Density distributional shifts to the right reveal even lower liquidity in the bond market, particularly, when linguistic complexity is high. The sensitivity of liquidity is more when the complexity of forecasting is high. Volatility of liquidity is also found to respond to linguistic complexity of the SARB communication. Main regression results indicate that liquidity is particularly responsive to complexity of overall communication and some specific topics - for example, Forecasting. High communication complexity of forecasting is found to lead to higher quoted spreads suggesting disrupted trading. These findings suggest that market participants respond distinctly to different levels of specific topic communication clarity, providing central banks practical insights to target improvements that promote stable market and economic outcomes.
Therefore, this thesis contributes to the existing literature in three distinctive ways. First, it addresses the limitations of traditional methods of temporal disaggregation of time series by proposing a simple novel, data-driven approach. Second, adds to the existing literature by producing fresh evidence confirming the differential impact of an aggregate financial shock on state-specific output growth. Finally, contributes a novel approach to grade central bank communication complexity by topic, improving financial market understanding and presenting opportunities for pinpointed improvements in central bank communication
Management reasoning in the wild: unravelling context specificity beyond diagnosis
No full textAbstract not currently available
Accountability of universities to students through student representation in the UK: discretion, governance, and bureaucracy
No full textAbstract not currently available
Essays on uncertainty and temporary employment
Get PDFThis dissertation examines uncertainty and temporary employment in the United Kingdom, a country affected by global economic shocks such as the Great Financial Crisis and COVID-19 but also uniquely characterised by exceptionally high uncertainty during the Brexit negotiations, and where temporary employment—defined as employment with a predetermined termination date—is a consistent feature of its labour market.
The dissertation begins by exploring the broader effects of uncertainty. The first chapter constructs industry division-specific microeconomic uncertainty measures for the UK and applies them within a panel vector autoregressive (VAR) framework to assess the impacts of uncertainty. The findings demonstrate that, despite being underutilised in the uncertainty literature due to a lack of disaggregated measures, panel VARs can provide evidence consistent with findings from the uncertainty literature that use aggregate data. Furthermore, they provide new insights into the heterogeneous effects of uncertainty. Specifically, the magnitude of investment decline following a microeconomic uncertainty shock varies significantly across divisions, even within the same industry. The analysis also reveals differences in debt dynamics between manufacturing and services industry divisions following a microeconomic uncertainty shock.
The dissertation then turns to the topic of temporary employment. Rather than providing an exhaustive overview of temporary employment in the UK, the second chapter complements the existing literature by focusing on underexplored areas, including reasons for temporary employment, gender differences, and geographical variations in trends and correlations with macroeconomic variables in the UK. Using probit regressions, this chapter provides preliminary evidence suggesting that uncertainty is associated with a higher probability of individuals being in temporary employment.
Finally, the dissertation brings together the themes of uncertainty and temporary employment. The third chapter provides novel empirical evidence of the positive association between uncertainty and the size of temporary employment through a VAR model. To account for these empirical results, the chapter proceeds with a partial equilibrium model that isolates the role of uncertainty in shaping labour composition. Simulations from the model show that uncertainty shocks initially reduce the aggregate share of temporary labour, but firms in the aftermath of heightened uncertainty become more cautious and subsequently react by favouring temporary labour over permanent labour. This shift is attributed to the higher adjustment costs associated with permanent labour that make hiring and firing mistakes more costly for permanent than for temporary labour
Fighting falsity: essays on deceiving, objecting, and conspiring
Get PDFThis thesis is comprised of five discrete but related chapters in applied, social, and political epistemology. Specifically, most of the thesis is centred around fighting falsity; that is, for example, what should you do when one someone asserts something wrong, outlandish, or flat-out dangerous to you or those around you? What is the best course of action if you come across such a claim on the internet? What sort of claims even are wrong, outlandish, or flat-out dangerous? I open with a discussion of bullshit and identify a new phenomenon I call “hedged bullshitting” which I argue is a superlative form of deception we ought to be concerned about. I turn in chapter two to a discussion of what makes for an epistemically good objection (and forbearance from objecting), employing the influential performance-normative framework from virtue epistemology to answer this. I then call for caution in chapter three; objecting can and will go wrong, especially when it comes to certain controversial false assertions, thus we ought to not be so laissez-faire when it comes to engaging with interlocutors. In light of this call for reticence, I explore a different method of fighting falsity in chapter four: censorship and no-platforming. While potentially effective strategies, I argue they make for hiltless swords—they cannot be safely used. In the final chapter, I offer a broad critique of the philosophy of conspiracy theories, rejecting almost every widely held assumption in the literature. I offer my own, more satisfactory definition of conspiracy theories that I argue will best advance the literature
A game of rISC – strategic molecular design for high efficiency OLEDs
Get PDFAs society becomes ever more concerned with energy efficiency, the performance of light emitting devices must improve significantly. Organic light emitting diodes (OLEDs) are now a mainstream display technology. Their high brightness and contrast, excellent colour tunability, ultra-fast refresh rates and the ability to be prepared in seemingly limitless form factors, makes them a highly attractive replacement for traditional display methods. Their flexibility makes them attractive to both medical applications and alternative lighting technology as well, and the fact that they can be fabricated from entirely organic materials allows them to be fully biodegradable and recyclable.
Unfortunately, they still suffer from roll-off effects and degradation through prolonged use, particularly for emitter materials utilising higher energy transitions, such as for blue pixels. As such, development of novel deep blue emitter molecules is vital for the more widespread adoption of this technology.
This thesis explores the synthesis and characterisation of novel, entirely organic, emitter molecules for OLED application. A broad review of the current literature of OLED materials is presented, followed by four synthetic themes.
Chapter 1 provides the reader with a history of light emitting devices and organic electronics, before summarising the basic requirements of, and fabrication of OLEDs.
Chapter 2 delves into the physics of semiconductors and introduces the photophysics of excited states and fluorescent and phosphorescent processes. It goes on to summarise the types of photophysical processes observed in emissive organic molecules.
Chapter 3 explores how chemical structure influences TADF in organic molecules and examines the literature, highlighting key developments that have led to our current understanding about the rules governing the fine tuning of the rISC process in state-of-the-art emitter molecules.
Chapter 4 explores a family of simple boron-based D-A type molecules, their photophysics and chemical stability, which helped to inform the design of further compounds in this thesis.
Chapter 5 reports the successful synthesis and photophysical characterisation of a family of six boron-based emitter molecules with varying acceptors and π-bridge structures. The interesting potential for non-covalent interactions between oxygen and the empty p-orbitals of the boron atoms are explored, giving promising results with attractive properties.
Chapter 6 builds upon the non-covalent interactions of Chapter 5 to produce a highly emissive and efficient D-A-D type molecule with a diboron acceptor core. Whilst its stability is poor, it possesses record-breaking emission lifetimes for its colour and demonstrates the highly effective nature of non-covalent interactions in producing HOMO-LUMO decoupling in the excited state.
Chapter 7 takes the interesting, but understudied, dibenzocarbazole donor moiety explored in Chapter 4, and produces a large family of novel emissive molecules. Not only do they mostly possess TADF, but they also all exhibit striking thermochromism and mechanochromism thanks to the quasi-helical nature of the extended carbazole moiety.
All experimental procedures, UV-vis absorption coefficient calculations, NMR and mass spectroscopy data and crystallography data, are collated in the appendices
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