Development of an interdisciplinary decision support tool to inform mangrove restoration and conservation in Vietnam’s deltas

Abstract not currently available

Decoupled electrolysis using silicotungstic acid as a redox mediator for zero-carbon hydrogen production

Water electrolysis for hydrogen production has substantial potential to address the current energy crisis while mitigating environmental pollution. However, achieving truly green hydrogen production requires using materials better suited to intermittent power generation, as existing systems pose serious concerns over gas mixing and cell component degradation. This thesis examines the concept of decoupled water electrolysis, utilising silicotungstic acid (H4SiW12O40) as a redox mediator in a flow-cell system to generate hydrogen. Decoupled electrolysis offers exceptional flexibility by enabling the separate production of hydrogen and oxygen at different times and rates, reducing gas crossover issues to a minimum. Chapter 1 explores the green hydrogen production route in a net-zero world and the various methods employed in green hydrogen production. Furthermore, we introduce the concept of decoupled water electrolysis, an emerging approach for green hydrogen production via electrochemical processes, and discuss how it can potentially address some of the challenges associated with renewable-driven hydrogen production. Chapter 2 provides background information on the theory underlying the experimental techniques used throughout this study. Various electrochemical and analytical methods were employed to monitor changes in potential, current, charge passed, and the electrode surface during the reduction of the redox mediator. Chapter 3 highlights the application of decoupled water electrolysis in a flow system using silicotungstic acid as the redox mediator by assembling two electrochemical cells for hydrogen production (mediator re-oxidation) and oxygen production (mediator reduction) while applying a range of commercially relevant current densities (0.05–1.35 A/cm2 ) to monitor the liquid mediator behaviour as it was circulated continuously between the two cells as hydrogen was produced. In Chapter 4, regenerated cellulose dialysis membranes were employed in the oxygengenerating cell, in order to compare the resulting electrochemical system with the one from Chapter 3 (which used only perfluorinated membranes). A comparative analysis of the membrane (before vs after electrolysis), current density, and the decoupling efficiency (%) obtained in this section was conducted. Chapter 5 contains overall conclusions and discusses future work. It provides a summary of the work and suggestions for future research

Forces controlling the dynamics of planetary interiors

Convection occurs naturally in the atmospheres of giant planets and within electrically conducting regions of terrestrial planets, such as Earth’s outer core. Over time, increasing attention has been given to these conducting fluid regions in astrophysical and geophysical bodies, as they are believed to generate magnetic fields through dynamo action. Therefore, understanding convection and the dynamo process is fundamental to explaining how magnetic fields are sustained in astrophysical and geophysical bodies. This thesis investigates convective fluid flows under the influence of rotation and magnetic fields. Numerical simulations are conducted using two models: an annulus model with an imposed magnetic field, and a spherical shell model that allows for the self-excitation of magnetic fields. Throughout this thesis, particular attention is given to the forces governing the flow dynamics. The first part presents a literature review of existing work and outlines the methods used in both models. New results from nonlinear simulations of an annulus model with an imposed magnetic field are presented. The study examines how varying the strength of magnetic field and convection affects the prevailing force balances and flow patterns. Additionally, the characteristics of zonal flows and multiple jets within the annulus model are investigated, with particular emphasis on the influence of magnetic field strength and the force balances required to sustain these flows. Zonal flows and multiple jet solutions are typically found at weak magnetic field strength where a strong inertial force is present, although some cases of zonal flows and multiple jets are found at strong magnetic field strength where a strong Lorentz force is present. Force balances occur that are similar to those found in the main regimes of dynamo action. Finally, spherical shell simulations are performed to investigate both forces and solenoidal forces, where flow lengthscales in two distinct directions are examined. Dynamically relevant flow lengthscales are identified by introducing a triple balance point involving key forces characteristic of the main dynamo regimes. These dynamically relevant lengthscales are then successfully compared with energetically dominant scales, highlighting how force balances at particular scales set the size of the flow. The forces and solenoidal forces across different regions of the spherical shell are further analysed. Transitions between the main dynamo regimes are examined, where solenoidal forces are used to explain the mechanisms driving these transition

Investigating the effect of HIV infection on TCR repertoire diversity and Mycobacterium tuberculosis-specific T cell function in Malawian adults

The burden of tuberculosis (TB) is huge, posing a significant health threat worldwide, particularly in HIV-endemic regions such as sub-Saharan Africa. Coinfection with HIV is a major risk factor for development and progression to active Mycobacterium tuberculosis (Mtb) disease. People living with HIV (PLHIV) remain at more risk of developing lower respiratory tract infections including TB than HIVuninfected individuals, despite successful coverage of antiretroviral therapy (ART). HIV depletes and impairs the function of Mtb-specific T cells crucial in controlling Mtb infection. However, the impact of HIV on T cell receptor (TCR) usage in alveolar T cells is incompletely described. Characterisation of TCR repertoire is essential for understanding the mechanisms of recognition and control of Mtb infections by T cell adaptive immunity. To investigate the Mtb antigen-specific TCR diversity and clonality in the airway and blood and assess the impact of HIV and ART on TCR diversity, peripheral blood and bronchoalveolar lavage (BAL) samples were collected from PLHIV ART–naïve, on ART (≥3 years) and HIV-uninfected adults recruited at Queen Elizabeth Central Hospital, Blantyre, Malawi. Alveolar and peripheral blood lymphocytes were stimulated with Mtb antigens and analysed using flow cytometry and TCR bulk sequencing. Notably, Mtb-specific TCR repertoires from PLHIV displayed a reduced diversity and clonality compared to HIV-uninfected individuals in both the airway and blood. Moreover, ART was associated with the restoration of TCR clonotypes in PLHIV. Additionally, lower frequencies of Mtb-specific CD4 IFN-γ and TNF-α producing cells were observed in both blood and airway in PLHIV on ART and ART naïve compared to HIV-uninfected individuals. Significant alterations in TCR Vβ expression patterns were noted in CD4+ T cells in PLHIV compared to healthy controls. Vβ1, Vβ7.2, and Vβ23 were higher, while Vβ9 and Vβ18 were lower in blood and airway in PLHIV than in HIV uninfected individuals. In CD8 T cells, no significant differences were found in TCR Vβ expression in the PBMC compared to BAL. However, in the lung, Vβ5.1, Vβ16, and Vβ17 were increased, while Vβ14 was decreased in PLHIV. Furthermore, CDR3 length distribution analysis showed a higher and more diverse distribution of TCR amino acid lengths of Mtb-specific T cells in BAL and PBMCs in HIV-uninfected individuals compared to PLHIV. The elevated TCR Vβ in the lung and blood in PLHIV suggests their potential involvement in HIV immune response whilst depletion of certain TCR Vβ clones in Mtb-specific CD4 and CD8 T cells in the lung and blood may indicate HIV-induced alteration in the repertoire associated with increased TB risk. These findings suggest a more restricted TCR repertoire in PLHIV compared to healthy controls, with alterations in the frequency of certain families that may impact antigen recognition and specificity. This could lead to a reduced ability to mount protective immune responses against infections, including Mtb, in PLHIV. Identifying highly used and expressed TCR Vβ segments provides insights into mechanisms of host protective immunity in HIV and TB and may offer crucial targets for vaccine development and preventive therapies

In bed with Kierkegaard

For the creative part of this thesis, I have submitted a novel in the genre of autofiction, titled In Bed with Kierkegaard. It is a fictionalised account of my initiation in a BDSM community in Athens, Greece, between the years 2007 – 2009, and an account of a long-distance relationship I developed with a dominant man, with the nickname Morpheus. The themes of the novel are: domination/submission and sadism/masochism in our modern digital age, the quest for a female identity defined by sexuality, and writing erotic memoirs. The novel is based on detailed notes kept during the narrated events and follows closely on the advice on seduction offered by the Danish philosopher Søren Kierkegaard in the text, The Seducer’s Diary. The critical part of this thesis provides a background account of writing a novel of autofiction on sadomasochism and seeking its publication. It also provides a comparative analysis of two literary works on similar themes, Dominique Aury’s Story of O, and Garth Greenwell’s Cleanness, especially as they pertain to the way in which erotic fantasy encroaches on reality, as well as the quest for what Kierkegaard called a ‘God-relationship’: a love and devotion so deep it may offer one a sense of transcendence beyond the limitations of human existence as grounded on the quotidian

Exploring the legacies of steel slag at Glengarnock, North Ayrshire: A situated interdisciplinary account of an anthropogenic geomaterial

The steelmaking furnace is a place where raw earth materials and human industrial activities meet. Steel slag is an entity that is encouraged to form through the intersection of these influences, as it is employed to withdraw and entrain natural chemical impurities, and hold these contaminants separate from the furnace’s nascent end products. Once it has completed this task, slag is dumped at the outer limits of a works landscape. Here— generally out of sight and out of mind— it enters into new relations with its surroundings. Steel slag does not occur naturally in our environment – its existence depends upon human agency. Yet its material origins and post-depositional afterlives are also shaped by environmental processes. Steel slag can thus be conceived of as an anthropogenic geomaterial, holding multi-temporal stories which can be traced by attending to the entangled worlds it encompasses. The potential of these narratives has however received almost no scholarly attention. This thesis presents an account of the steel slag that forms one of the last remaining physical vestiges of the former Glengarnock Steelworks in North Ayrshire, Scotland. The deposition of this slag into a loch closely neighbouring the works gradually claimed an entirely new anthropogenic landscape from this waterbody, which has in recent years been shaped by a local authority led regeneration project. I develop an interdisciplinary approach— that emerges from the particular juxtaposition of my research context and the three disciplines of geography, archaeology and geology— to explore the past, present and possible futures of this place, positioning its slag as a once largely forgotten, but now newly re-encountered material legacy that simultaneously manifests as a waste product, a post-industrial remnant, and as a novel anthropogenic rock. In so doing, I demonstrate how a personal engagement with this slag’s stories can be used to reanimate taken-for-granted histories, rewrite emerging heritage narratives, and re-imagine carbon futures. In this thesis, I am continuously challenged and surprised by Glengarnock’s steel slag, yet I also come to care about this neglected industrial waste deposit. I find ultimately that electing to pay attention to a local outcropping of an anthropogenic geomaterial reveals choices, and that exploring what can be done with our material legacies, as well as what might be conferred as a result, can contribute to the task of working though the world shaping implications of humanity’s assumption of geological force

A theological study of hyper-Calvinism in the writings of Joseph Hussey (1660-1726), John Skepp (1675-1721), John Gill (1697-1771), and John Brine (1703-1765)

No abstract available

Predicting retrieval failures in conversational recommendation systems

In recent years, the use of dialogue systems and voice assistants commonly implemented in smart devices has shifted the users’ interest towards online shopping. In turn, online shopping platforms are gaining popularity and moving towards allowing an interactive dialogue with users that more accurately depicts a real shopping setting. In this regard, the task of Conversational Image Recommendation is the state-of-the-art task for conversational recommendation in the fashion domain, where a user has a specific fashion item in mind, and interacts with the system with natural language feedback on recommended image items, which guides the system in finding the imagined item in the next turn. Such systems are trained and evaluated with user simulators as a plentiful surrogate for human users. A practical problem with CRS performance is that it is primarily evaluated in terms of successes and is therefore assumed to return the item of interest by a pre-defined number of turns. In practice, often the item is not returned by the end of a conversation, therefore leading to conversational failures; this is our particular setting of interest. In this thesis, we argue that the performance of a Conversational Recommendation System can be predicted to detect when a conversation fails, under different scenarios, across different turns of a conversation. In this regard, Query Performance Prediction (QPP) techniques predict the effectiveness of a ranked list result in response to a query without having access to relevance judgments. We predict the performance of CRS models by treating them as dense retrieval processes, where both the image retrieved items and textual feedback can be represented with dense embedded representations. In particular, we propose a set of coherence-based dense QPPs specifically designed for single-representation dense retrieval models (ANCE and TCT-ColBERT) and show that the examination of the relations among dense embedded representations already contained in the document list is sufficient to provide effective predictions for dense retrieval models. At the same time, by using a multi-level perspective that jointly considers QPPs and types of queries, we explain why some QPPs are better for certain types of queries, thus explaining discrepancies among different evaluation metrics. At the next stage, we predict the effectiveness of a ranking of image items in Conversational Image Recommendation models, which are also based on learned embedded representations of images, and where user feedback takes the place of a textual query. In deed, we create a novel task which we call Conversational Performance Prediction (CPP), which predicts conversation success at the conversation level and taking into account the multi-turn nature of the task, and can differentiate between success predicted over a short-term and a long-term horizon, thereby predicting current user satisfaction or overall satisfaction of a conversation. First, we examine the set of unsupervised predictors developed for dense retrieval models but applied to state-of-the-art Conversational Image Recommendation models; a GRU-based model, which mainly considers the feedback of the previous turn, and an EGE model that considers the entire dialogue history. Our results show that using correlations is not an optimal evaluation strategy for predicting conversational failures, as, while correlations are low to medium mainly for short-term predictions, a lot of inconsistencies are observed among the performance of different predictors across metrics and datasets (similarly to dense retrieval models). Consequently, we propose a supervised CPP approach, which treats CPP as a binary classification task, which predicts whether a target item is returned by a given turn. In this way, we show that by learning the embedded representations already contained in the CRS models, we can predict the accuracy of a conversation success using the retrieved items of both single and multiple turns. In addition, state-of-the-art CRS models are trained using user simulators with a single target item in mind, and at the same time, they are assumed to be infinitely patient. These settings do not reflect a real shopping scenario, where a user might change their mind according to what a shopping assistant is suggesting. For this purpose, we enhance the evaluation completeness of CRS models by obtaining real user opinions in a user study using pooling similar to information retrieval tasks, thus identifying alternative relevance labels for several target items, and in turn, inform the user simulator with an extended target space. This increases the completeness of CRS evaluation, and therefore, creates a more realistic prediction setting for CRS, which leads to improved predictions of user preferences. Indeed, when we reevaluate the CRS models using the updated simulator with the identified alternatives as part of the target space, we show that by the single target setting previously used to evaluate CRS models for a maximum amount of 10 turns was underestimating the effectiveness of CRS models. As a final step, we account for the fact that CRS models assume only one type of recommendation failure, namely the inability of the system to retrieve the target item. In this regard, we introduce the concept of recommendation scenarios, and specifically, we adapt our CPP framework for different types of conversational failures, which are determined by whether the user’s need is clearly defined and whether the target item is available. Therefore, we propose the removed target scenario (the target is not available in the catalogue), and the alternative scenario (a user has a more flexible need, which can be satisfied by either the original target or any of the identified alternatives in the collected datasets). Consequently, we detect different types of conversational failure, such as when a user cannot find an item, versus when the system’s catalogue does not contain the relevant item. By examining the supervised CPP predictors introduced under these two novel scenarios, we find that in both cases, there is a marked difference from the original scenario, and that CPP can indeed be predicted for different recommendation scenarios

Tribal influence on corporate governance in Nigerian firms

Publicly listed firms are composed of different parties, with the Board of Directors (BoDs) as the primary force influencing the firms’ governance (Baysinger & Butler, 1985; Fama & Jensen, 1983a; Williamson, 1983, 1984 as cited in Hassan, Marimuthu & Satirenjit, 2015). As a result of having multiple parties on a single board, there are always divergent interests (Eisenhardt, 1989). As such, a critical challenge with governance is aligning and balancing the interests of a company’s many stakeholders, especially those represented on BoDs in multi-ethnic settings. The multiplicity of their ethnicity can create complicated, divergent interests, even within their group. The shareholders’ role in governance is to appoint directors who apply appropriate governance to ensure the parties’ interests are represented. In contrast, the BoD’s role is to act on behalf of the shareholders via their control. This control exists along with and depends on the control of other stakeholders. The question arises: Is the board members’ capacity to exercise control influenced by any tribal connections among them? Or are tribal affiliations among shareholders’ representatives and managers associated with Type 1 agency costs? To address this question, this research initiates a review of corporate governance research, focusing on agency theory. Agency theory was chosen as a theoretical framework to explain many strengths and weaknesses of corporate governance, i.e. the structures that specify the distribution of rights and responsibilities. It also predicts the implications of relationships among various parties in controlling and directing the activities of a firm, e.g., understanding how tribal affiliations can influence a BoD’s capacity to perform its functions and reduce agency costs. First, the assumptions of agency theory are covered in the literature review. For a company with tribal ownership and/or control, agency theory predicts higher Type 1 agency costs (i.e., relating to tribal ownership and managerial control) and Type 2 agency costs (i.e., relating to tribal share ownership). However, following the data analysis, this research's empirical results contradict the negative prediction of agency theory for the predominant Nigerian tribe. Hence, alternative proximate theories like network, stewardship, and stakeholder theories as alternatives to agency theory may explain this refutation and comprehend the intricacy of interpersonal relationships within a firm

The creative uses of Irish literature in works by J.R.R. Tolkien

The aim of this thesis is to examine the significant and sustained influence of Irish literature across the corpus of J.R.R. Tolkien’s mythopoeic writings— what is frequently termed as his “legendarium” —and to analyse how he adapted and creatively revised Irish sources in his writings. Some of Tolkien’s statements have given the impression that he did not like, nor was he influenced by, Irish language or literature, and yet scholars have long identified Irish elements in his writings and called for a deeper appreciation of them. This thesis presents the first book-length, systematic critical analysis of the role of Irish literature in Tolkien’s legendarium. It includes the identification and critical analysis of specific works of Irish (and Irish-themed) literature and language study that Tolkien owned, read, is suspected to have read, and/or referenced, including his volumes donated to the Bodleian and English Faculty Libraries at the University of Oxford, and it presents a curated selection of new observations and findings on Irish influences in his writings. As the question of how Tolkien’s work relates to Irish antecedents has been under-researched, this thesis breaks new ground by approaching Irish literature as a major category of Tolkien’s sources and influences