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Topics in stochastic numerics with applications in finance and optimization
Get PDFThis thesis is devoted to the study of two topics related to the application of numerical solution of stochastic differential equations (SDEs). First, we consider variance reduction for Lévy-driven SDEs. We develop optimality conditions for the variance reduction and propose a numerical algorithm for efficient variance reduction. The algorithm makes use of a neural network in order to approximate a control variate. Several numerical examples from option pricing are presented.
Second, we study reflected McKean-Vlasov SDEs in smooth bounded domains, for which we prove well-posedness and propagation of chaos. We also consider their application to constrained optimization problems via consensus-based optimization (CBO). We propose two CBO models, for which numerical approximation schemes correspond to constrained optimization algorithms. We test the performance of these algorithms on benchmark optimization problems as well as on an inverse problem
Optimisation of Ligand-Directed Labelling Probes for A1 Adenosine Receptors in Whole Cells: Development and Evaluation
Get PDFAdenosine receptors (ARs) are widely distributed throughout the human body and exist in four subtypes: A1, A2A, A2B, and A3. The endogenous ligand adenosine modulates numerous physiological responses across various tissues and organs, including the cardiovascular system and both the central and peripheral nervous systems, through activation of these receptors. Among them, the A1 adenosine receptor (A1 AR) has been extensively investigated as a therapeutic target for conditions such as arrhythmia, heart failure, neuropathic pain, and diabetes. However, no A1 AR-targeting candidate has successfully completed clinical trials and reached the market. Challenges in drug development stem not only from the complexity of the A1 AR system but also from an incomplete understanding of its interactions with other proteins and its diverse cellular responses.
Dr. Comeo E. developed ligand-directed (LD) covalent labelling probes for A1 AR. One probe directly transfers a sulfo-Cy5 fluorophore to A1 AR, while the other transfers a trans-cyclooctene (TCO) handle. The covalent sulfo-Cy5 tag enables real-time visualisation of receptor localisation and trafficking. Additionally, protein–protein interactions involving A1 AR can be studied using techniques such as BRET, FRET, and FCCS. The TCO handle allows broader applications via inverse electron demand Diels–Alder (IEDDA) reactions with tetrazine-conjugated reporters, which may include fluorophores, biotin, or radiolabels, depending on experimental design. However, both subtype selectivity and labelling efficiency require further optimisation.
This thesis presents the design, synthesis, and pharmacological evaluation of novel LD probes based on Comeo’s templates. Probe 5-8, a sulfo-Cy5 transferring LD probe, improved A1/ A2A selectivity from 5.9-fold (Comeo’s original probe) to 40-fold, while maintaining selectivity over other AR subtypes. Probe 4-5, a TCO-transferring LD probe, enhanced A1/ A2B selectivity from 60-fold to 210-fold. Parameters such as the click reaction pair, buffer or medium composition, probe concentration, and incubation time were systematically investigated to optimise labelling efficiency.
In addition to using agonist-induced internalisation to assess orthosteric binding pocket accessibility post-labelling, a BRET-based assay was conducted with probe 4-5. FRET between the AF488 tag (introduced via probe 4-5 and a tetrazine-AF488), along with a red fluorescent reversible ligand 3-29 (BODIPY630/650), confirmed the availability of the orthosteric binding site. These findings were further validated using FLIM-FRET experiments.
The novel LD probes 5-8 (sulfo-Cy5) and 4-5 (TCO), with improved subtype selectivity, represent valuable tools for advancing the study of A1 AR biology. These tools are expected to facilitate deeper exploration of A1 AR pharmacology and contribute to expanding our understanding of its therapeutic potential
Consequences of energy demand reduction interventions to the Chilean housing stock on energy poverty
Get PDFThe consequences of energy demand reduction interventions on energy poverty within the Chilean housing stock were investigated. Energy poverty, defined as the inability to afford adequate warmth due to inefficient housing, was examined in the context of Chile’s diverse climates and economic challenges. The study used a mixed methods approach, integrating quantitative data from the Family
Budget Survey and qualitative insights from the Uses of Energy in the Chilean Housing Survey. The key factors contributing to energy poverty, including low income, educational attainment, property tenure, energy prices, household size, and housing energy inefficiency, were analysed.
Households in Thermal Zones 5 and 7, characterized by severe climates and high energy demands, were identified as particularly vulnerable to energy poverty. Energy modeling using EnergyPlus demonstrated that interventions such as roof, wall, and floor insulation, along with double glazing,
could significantly reduce heating energy demand. The analysis revealed that roof insulation had the most substantial impact, followed by wall insulation, while floor insulation and double glazing contributed marginally. The concurrent application of all interventions led to substantial reductions in heating demand, highlighting the importance of targeted energy efficiency measures.
The findings underscore the need to implement customized energy efficiency measures to alleviate energy poverty and improve the quality of life of affected households. Policymakers are advised to prioritize interventions that offer the most significant impact on reducing energy demand, particularly roof and wall insulation. Future research should focus on improving the accuracy of data
on parameters such as infiltration rates, building orientation, and heating usage patterns, as well
as exploring the long-term benefits of energy efficiency measures on health and well-being
Learning to rank salient objects using transformers and graph reasoning
Get PDFThis thesis explores the domain of salient object detection, aiming to find the most visually important objects within a given image. Many of the current approaches have focused on datasets with many images containing only a single salient object located towards the center. We focus here on the more complex task of images containing multiple objects, where relative saliency between objects must also be evaluated. A novel multiple salient object detection framework is proposed, utilizing both spatial and channel-wise non-local blocks within a convolutional network. The experiments compare the approach against 14 state-of-the-art methods on five widely used SOD benchmarks and a newly curated multi-object dataset. The proposed method exceeds all previous state-of-the-art approaches in three evaluation metrics and provides a further performance boost against competing techniques on the proposed dataset.
We then build upon this work to investigate the multiple salient object detection task in greater depth, exploring the problem of instance-level relative saliency ranking. This is an emerging field, and considering the lack of appropriate datasets in this domain, we produce a large-scale instance-level relative saliency ranking dataset using real human fixations. To the best of our knowledge, this is the first and largest dataset created by real human fixations for relative saliency ranking. A novel framework is then introduced that models multi-scale ranking-aware information cues in a nested style graph, drawing features from a query-based transformer. Experimental findings demonstrate the effectiveness of this proposed method. We exceed all previous state-of-the-art approaches with a large margin under three evaluation metrics. The model and full dataset will be released into the community
Essays on political influence and sustainability in banking and financial markets
Get PDFThis thesis investigates the effects of environmental events and public governance within the Chinese context, focusing on three key research questions: (1) Do local firms strategically enhance Corporate Social Responsibility (CSR) following regional pollution emergencies? (2) How does the 'policy mix' of green credit policies and government subsidies influence high-quality environmental innovation in high-polluting firms? (3) What is the impact of political corruption on stock liquidity?
Utilizing a large sample of Chinese listed firms, this thesis employs robust empirical methods, including instrumental variables, propensity score matching (PSM), and difference-in-difference tests, to ensure the validity of its findings. The research reveals that firm-level outcomes are significantly influenced by regional pollution emergencies, environmental policy mixes, and political corruption.
Chapter 1 addresses the rising incidence of pollution emergencies in China and examines how local firms use CSR initiatives to build trust and counteract negative stakeholder sentiments following severe pollution events. It identifies political dependency, institutional ownership, and public monitoring as primary drivers of enhanced CSR activities, contributing to the literature on corporate responses to environmental shocks.
Chapter 2 explores the impact of the Green Credit Guidelines (GCGs) in China and the moderating role of government subsidies. The findings indicate that GCGs negatively affect high-quality environmental innovation among high-polluting firms, but government subsidies can mitigate this negative impact. This work adds to the literature on the implications of environmental policy mixes.
Chapter 3 investigates the relationship between political corruption and stock liquidity, revealing that local political corruption negatively impacts stock liquidity through informational channels and investor trading activities. This chapter contributes to the extensive research on the effects of corruption.
By focusing on environmental innovation, CSR, and stock liquidity, this thesis highlights significant contributions to the broader literature on political influence and sustainability in banking and financial Markets
Women in Livy: performativity and historiographical conventions
No full textThis thesis examines three social roles occupied by women in Livy – those of daughters, wives, and mothers. The final chapter, ‘Others’, considers the intersection between gender and ethnicity by examining Livy’s presentation of ‘non-Roman’ female protagonists. This thesis will demonstrate that Livy’s character types revolve around androcentric expectations for female familial roles and Romano-centric stereotypes for certain ethnic groups that were considered outsiders.
This thesis argues that Livy uses a series of linguistic and narrative frameworks to perpetuate female character types. These character types are not Livian inventions: they are a combination of social expectations and pre-established female characterisation not only from historiography, but gynocentric stock characters from the genres of tragedy and comedy. Livy unpicks and deconstructs these characters in episodes that contain tragic motifs, dramatic stagecraft, and performance. This thesis explores Livy’s appropriation of female characters through a male lens and argues for the complex and often transgressive characterisation of female protagonists as told through a series of tragic performances.
There is currently no comprehensive analysis of the intersection between women, drama, and performance in Livy. In previous scholarly research these topics have been analysed separately with a focus on select protagonists from the first pentad. This thesis is the first to consider female character types and performativity through an extensive study of Livy’s narrative strategies, with a focus on intratextuality between the first pentad (books 1-5) and the third and fourth decades (books 21-45)
Legal and policy barriers to phasing out fossil fuels in the Global South: the case of Mozambique
No full textThis thesis explores the legal and policy barriers to phasing out fossil fuels in the Global South, focusing on Mozambique as a case study. The urgent need for a global fossil fuel phaseout is driven by fossil fuels’ pivotal role in climate change. This thesis highlights the complex interplay between Mozambique’s economic dependency on fossil fuels and the global imperative to reduce greenhouse gas emissions.
The analysis is divided into three core chapters, each addressing specific legal and policy challenges. The first chapter critiques the limitations of the UN Climate Regime in fostering a coordinated global approach to phasing out fossil fuel production, particularly for Global South countries like Mozambique. The second chapter investigates the role of international investment law in protecting fossil fuel investments, which poses substantial economic and legal risks to Mozambique and locks it into a high carbon cycle for the foreseeable future. The final chapter scrutinises the influence of official development assistance on Mozambique’s development pathway, revealing that current aid may not be Paris-aligned.
The thesis concludes by advocating for a reevaluation of Mozambique’s national policies and international cooperation frameworks to better align with sustainable development goals and climate commitments. It calls for strengthened international cooperation to support Mozambique’s transition away from fossil fuels, emphasising the responsibility of Global North countries to facilitate this shift
Sleep disturbances, unusual experiences, and suicidal ideation in first episode psychosis: an exploratory mixed-methods study
Get PDFIntroduction. Sleep disturbances are a risk factor for suicidal ideation and are commonly reported amongst individuals experiencing psychosis. Given elevated suicide risk in First Episode Psychosis (FEP), understanding associations between sleep and suicidality is imperative for informing risk management and intervention. This study explored associations between sleep, psychosis symptoms, and suicidal ideation and explored the perceptions of those with FEP regarding these experiences.
Methods. 10 participants experiencing FEP were recruited from Early Intervention services. Participants wore an actigraph for 7 days, completed 3 measures (Insomnia Severity Index [ISI], Prodromal Questionnaire Brief [PQB], and Beck Scale for Suicidal Ideation [BSS]), and participated in a semi-structured interview.
Results. No significant associations were found between variables, which was expected in this exploratory study. Descriptive statistics indicated variation in sleep duration, sleep timing, wake after sleep onset, and onset latency. Qualitatively, participants described an extended process of loss, from losing sleep to ‘losing themselves’ and the ability to make safe decisions. Sleep disturbances were considered central to the meaning making of psychosis experiences prior to an acute episode, and as a ‘trigger’ for subsequent experience. Participants discussed reduced emotional control and heightened self-harm or non-suicidal self-injury following sleep disturbances. Participants described a sense of entrapment in their experiences of poor sleep and described suicide as an escape from their current reality.
Conclusions. The relationship between sleep and suicidality in FEP warrants further exploration, including understanding of how specific aspects of sleep relate to suicidality, and exploration of the psychological processes in this complex relationship
Measuring anxiety about ageing and ageism: eye-gaze patterns, facial ageing trajectories and implicit associations
Get PDFThis study aims to investigate ageism and anxiety about ageing among young adults via the Brief Implicit Association Test (BIAT) and eye-tracking, where gaze patterns towards faces of different ages and identities are analysed. Thirty-four female undergraduates (Mage = 20.68) completed the self-reported ageism and ageing anxiety scales, BIAT and a passive-view eye-tracking paradigm in which they viewed the age-manipulated faces across three facial identities (the self, familiar “friend” and the unfamiliar “other”). One sample t-tests against the cut-off scores of the respective scales indicates that participants reported significantly more positive attitudes towards older adults and marginally low ageing anxiety, on average, via self-reported measures. However, via the BIAT, on average, participants held ageist attitudes towards older adults. The attitudinal discrepancies between implicit and explicit measures of ageism supports the precedence of implicit attitudes under cognitive load. Regardless of facial identities, participants fixated significantly longer and more frequently at the eye regions compared to other facial regions, especially for old-aged faces. Old-aged faces were rated the least pleasant but most arousing. Facial images of the self were rated the most arousing. Though explorative in nature, findings of gaze patterns are consistent with the crucial roles of eyes and the Expert Hypothesis of facial processing. This sheds light on visual processing when viewing faces of different ages and identities, besides highlighting the attitudinal complexities of young adults towards older individuals. Findings also opens potential avenues for the integration or micro-behaviors and non-verbal communication strategies to supplement existing intergenerational efforts in mitigating ageism
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