VictorJuiz/thesis huggingface dataset:
Shape optimisation and robust solvers for incompressible flow

When designing a new car or a plane, engineers need to solve the Navier-Stokes equations to understand how air flows around the object. Based on experience and intuition, they modify the design slightly, then solve the equations again, and inspect the changes. This process is iterated many times until a final design that minimises or maximises some quantity of interest, such as drag or lift, is found. The goal of shape optimisation is to automate this type of process.
In this thesis we address several issues related to shape optimisation. Focussing on the case when the shape is discretised using a mesh and when PDE constraints are solved using the finite element method, we describe a reformulation of the shape derivative as the derivative of the pushforward from the reference element. This viewpoint allows for automated calculation of shape derivatives in finite element software. When shape optimisation is performed by deforming an initial mesh, the choice of deformation is important. We propose a new Hilbert space structure on the space of deformations that results in high mesh quality of the deformed domains.
We then focus on the solution of a particular PDE constraint given by the steady, incompressible Navier–Stokes equations that govern laminar flow. The solution of these equations becomes challenging for large Reynolds number. We develop augmented Lagrangian based preconditioners that exhibit robust performance as the Reynolds number is increased. The effectiveness and scalability of the developed solvers is demonstrated for a range of test problems.

Keywords: Numerical Analysis
Computational Mathematics
Finite Element Method
Computational Fluid Dynamics
Navier Stokes Equations
Shape Optimisation
Applied Mathematics
Advisor: Farrell, P
Crafting elections under authoritarianism: electoral manipulation as an authoritarian response to uncertainty in Russia’s regional legislative elections

Authoritarian elections are becoming a common phenomenon, at the heart of which lies a range of manipulative practices designed to perpetuate authoritarian victory. This dissertation examines the patterns in electoral manipulation and probes the existence of a systemic logic behind the use of such tactics in Russia. Conventional wisdom assumes that authoritarian elites engage in manipulation from a position of strength - they spot opportunities to exercise their power over a weak electorate and interfere with elections in order to obtain impressive results that serve to stabilise and prolong authoritarian rule. In contrast, this dissertation proposes that authoritarian regimes interfere with elections out of weakness - manipulation is a way of overcoming uncertainty over how voter sentiments will translate themselves at election time in difficult electoral contexts.
The study narrows down the concept of manipulation to four major strategies (electoral fraud, candidate exclusion, spoiler candidates and voter mobilisation), and uses a wide range of electoral and candidate data, citizen reports and court cases. Focusing on the sub-national elections to Russia’s regional legislatures, the thesis argues that there emerge common intra-regional trends in the use of electoral manipulation, which point to the existence of a regime-wide logic. Specifically, the dissertation explains how uncertainty affects the strategies adopted, with a particular focus on how strategies vary across urban and rural districts. I argue that electoral uncertainty increases with the level of urbanisation, and subsequently examine the extent to which the deployment of manipulative strategies varies according to the urban-rural divide. As a result, this thesis seeks to enhance our understanding of electoral authoritarianism by identifying the contexts in which certain strategies of manipulation are more likely to be used.

Keywords: Russian regional elections
candidate exclusion
electoral authoritarianism
electoral manipulation
voter mobilisation
electoral fraud
spoiler candidates
authoritarian elections
Advisor: Chaisty, P
Affinoid enveloping algebras and their representations

We develop the basic theory of Picard algebroids and twisted differential operators on a smooth, reduced, locally of finite type scheme over a commutative ring. We also give a new geometric proof of the classical Duflo's theorem. We next move to the study the affinoid enveloping algebra of a semisimple Lie algebra defined over a discrete valuation ring. We prove that there exists a one-to-one correspondence between the lattice of submodules of an affinoid Verma module of a given weight and the corresponding classical Verma module. Finally, we classify all the primitive ideals in the affinoid enveloping algebra and prove that a large class of two-sided ideals in the affinoid enveloping algebra is controlled by two-sided ideals in the classical enveloping algebra.

Keywords: p-adic representation theory
Lie Algebras
Non-commutative rings
D-modules
Advisor: Ardakov, K
Investigating chlorsulfuron toxicity and resistance in the liverwort Marchantia polymorpha

Herbicide metabolic resistance is defined as the enhanced ability to metabolically detoxify herbicides. Enzymes that metabolise herbicides belong to the 71 and 72 clans of the cytochrome P450 (CYP) enzyme family and the Tau and Phi classes of the glutathione s-transferase (GST) enzyme family. I show that the 71 and 72 clans and Tau and Phi classes arose before the evolution of land plants and rapidly expanded in seed plants.
Using RNA-Seq and over-expression constructs I show that a 71 clan CYP up-regulated by the herbicide chlorsulfuron in the liverwort Marchantia polymorpha conferred a low level of resistance to chlorsulfuron when over-expressed. Chlorsulfuron treatment of sensitive plants caused the differential expression of hundreds of genes, while target site resistant (TSR) plants that possess a point mutation in the chlorsulfuron molecular target MpALS did not exhibit a transcriptional response to chlorsulfuron. This indicates that changes in steady state mRNA levels after chlorsulfuron treatment are caused by the chlorsulfuron-inhibition of ALS and not by the detection of the herbicide chemical in the plant. This suggests that the transcriptome response to chlorsulfuron represents a stress response to the disruption of the ALS enzyme, and is not a xenobiotic response. To test this, four of the most transcriptionally induced genes in response to chlorsulfuron were over-expressed in M. polymorpha. Only one gene conferred weak chlorsulfuron tolerance when over-expressed. This supports the hypothesis that plants do not possess a xenobiotic detoxifying suite of genes.
To determine how MpALS inhibition leads to plant death I generated loss of function (LOF) mutations in the MpALS gene. I show that the deletion of MpALS is lethal but the growth of Mpalslof mutants can be partially restored on medium supplemented with branched chain amino acids. Using targeted and untargeted metabolomics I show that chlorsulfuron-treatment reduces the abundance of some branched chain amino acids and increases pools of other amino acids and metabolites. I propose the hypothesis that chlorsulfuron lethality is due to a lack of branched chain amino acids which leads to large changes in gene expression.

Keywords: Cytochrome P450
Marchantia polymorpha
Glutathione S-transferase
Chlorsulfuron
Toxicity
Herbicide metabolic resistance
Advisor: Dolan, L
Exploring art as a means for communication and connection: From technology-enhanced art experiences to the Paradox of Sad Art

Art is a powerful form of communication between artists and audiences. In this thesis, I will explore two questions that emerge from the literature on art as a means of communication and connection between artist and audience: 1) how can technology be used to augment the sense of psychological connection between the audience and artist? and 2) why do we like sad art?
To answer the first question, Chapters 2 and 3 present experimental data showing that listening to music while wearing haptic devices (versus no haptics) and headphones (versus speakers) increases empathy, parasocial bond, and loyalty towards the artist and also decreases feelings of loneliness in the listener. Results indicate that feelings of social presence mediate the relationship between these immersive technologies and these measures of psychological connection to the artist. To answer the second question, Chapter 4 presents data from five experiments. Studies 1 and 2 show that framing a text as art versus not-art increases liking for the negative emotions expressed in it. Study 3 showed that there was an effect of art/not-art on liking even after controlling for differences in perceived fictionality between art/not-art. Study 4 found that appropriation mediates the effect of art/not-art on liking and, thus, explains liking for sad art. Study 5 controlled for a possible confound in the study design and found that the results replicated. Together, this thesis explores art as a means of communication and connection by providing new insights on the use of technology to enhance connection with artists and by finding empirical evidence to support the philosophical debate on the enjoyment of sad art. These studies shed light on the ways in which art can be used to connect with others and also connect with ourselves and our own emotions.

Keywords: psychology of technology
emotion
media psychology
psychology of art
Advisor: Knobe, J
Wang, QJ
Bowes, L
Hadi, R
Reading risk: collisions of crisis in contemporary American literature

This thesis examines representations of risk in contemporary American literature, joining a growing body of critical attention to risk and its relevance to literary studies. Framing risk as a matter of perception and therefore a matter of reading, this project explores how the interlocking structure of contemporary crisis both reflects and demands new critical approaches. This inquiry therefore undertakes a comparative study of how different forms and genres articulate and account for risk.
Risk is an analytical tool capacious enough to read across the range, scale, and complexity of contemporary crisis. To focus this expansive archive, this project is grounded at the intersection of two contemporary crises that anchor the modern “risk society”: terrorism and environmental destruction (Beck, Risk Society 9). These two categories of risk have also shaped American literary studies’ engagement with crisis over the last two decades, primarily through the subdisciplines of post- 9/11 analysis and ecocriticism. Building connectivity between these bifurcated discourses, this project accounts for risk in contemporary American literature inductively through a study of nine texts. Chapter One explores risk’s circulation through the networks of Jonathan Franzen’s Freedom (2010) and Laila Halaby’s Once in a Promised Land (2007). Chapter Two investigates rupture and continuity in Cormac McCarthy’s The Road (2006) and Colson Whitehead’s Zone One (2011). Chapter Three considers contradictory constructions of risk’s universality and particularity in Gayle Brandeis’s Self Storage (2007), Michael Cunningham’s Specimen Days (2005), and Ben Lerner’s 10:04 (2014). Chapter Four, through the case studies of Dave Eggers’s Zeitoun (2009) and Mohamedou Ould Slahi’s Guantánamo Diary (2017 [2015]), explores the tension between risk as exceptional and risk as routine.
Providing a corrective to what we might call “single-issue criticism,” this thesis will demonstrate how contemporary literature is already teaching us how to read across risk by making the convergences of crisis visible and offering immanent criticism of the ways risk is plotted and conceptualized.

Keywords: Post-9/11 Literature
Ecocriticism
Contemporary American Literature
Risk
Advisor: Boehmer, E
Kelly, M
Gottfried Hermann's laboratory: meaning and methods in early nineteenth-century classical scholarship

This thesis focuses on Gottfried Hermann and his philological practices, considered especially with a view to his dispute with August Boeckh in the early 1800s. Through an analysis of Hermann’s scholarly persona in the context of German academia, his theory of metrics and hermeneutics, and of the issues at stake in the dispute, this thesis keeps as a background reference the categories of Wortphilologie and Sachphilologie, which are traditionally associated with Hermann and Boeckh respectively. It aims to show that these two categories are methodologically unjustified and instead highlights the prominence of the socio-biographical aspect of their origins and presence in the history of classical scholarship. The examination of Hermann’s philology is conducted through a close reading of primary sources, discussions of his own textual-critical analysis, and archival materials. The conclusion underlines the need for a re-evaluation of Hermann’s scholarly work, with particular regard to his methods and hermeneutics; it also, more broadly, calls for further inquiry into Hermann’s work of the type that would encourage the rejection of the faulty idea of Wortphilologie in association with Hermann, arguing that the label generated implications which are part of the reason for Hermann’s underrepresentation in modern scholarship of intellectual history.

Keywords: hermeneutics
gottfried hermann
metrics
19th-century philology
sachphilologie
classical scholarship
classical philology
wortphilologie
august boeckh
philologenstreit
Advisor: Guthenke, C
Essays in empirical labour and public economics

This thesis comprises three essays in empirical labour and public economics. Chapter 1, co-authored with Anne Brockmeyer, Marco Hernandez, and Stewart Kettle, concerns taxation and economic development. The majority of firms in developing countries are informal, yet even among firms registered with the government, tax filing rates are low. We argue that nonfiling of taxes among registered firms constitutes an important intermediate form of informality, which can be tackled cost-effectively. Using a randomised experiment in Costa Rica, we show that credible enforcement emails increased tax filing and payment rates among previously nonfiling firms. Emails that highlight third-party reports of a firm’s transactions further increased compliance. The effect persisted over two years, and treated firms became more likely to report transactions with other firms, facilitating future tax enforcement.
Chapter 2 considers the wage effects of liability for employment discrimination. In both a standard competitive model and a monopsony model of the labour market, the net theoretical effect of liability for employment discrimination is ambiguous. Therefore, whether liability for employment discrimination increases the wages of protected workers and, if so, by how much, is an important empirical question. This essay proposes an empirical strategy to estimate the effects of liability for employment discrimination, using discontinuities in coverage of United States antidiscrimination law and in damages awardable in discrimination lawsuits based on firm size. Future work will aim to use confidential employer-employee matched data held by the U.S. Census Bureau. However, preliminary estimates using survey data suggest that coverage under federal antidiscrimination law increased relative wages for black men by 12 to 16 percent.
Chapter 3 uses data from the London Metropolitan Police Service to investigate discrimination in police searches and to estimate the effects of body cameras on discrimination. Prior to a body camera trial, black individuals were 2.5 times more likely to be searched than white or South Asian individuals, and men were 15.8 times more likely to be searched than women. These disparities cannot be completely explained by accurate statistical discrimination, as there were significant differences in search success rates between groups—differences consistent with preference-based or inaccurate statistical discrimination against young minority-ethnic men. Using variation in body camera use resulting from a one-year camera trial, I find suggestive but not conclusive evidence that cameras reduced these disparities somewhat, particularly the gender difference in search success rates.

Advisor: Adams-Prassl, A
Bell, B
Multi-agent learning

Machine learning models are often trained on data stored across multiple computers connected by a network. Due to network stability, it is then often infeasible for a single central-hub computer to process and disseminate information. A solution to overcome this bottleneck is to consider a decentralised network akin to peer-to-peer and ad-hoc wireless networks. Namely, computers communicate to a sub-set of other computers at a time, with information then naturally propagating through the network.
This thesis investigates the statistical performance of models produced in such a decentralised framework. By modelling the network of computers as agents in a graph, we investigate two different statistical settings: homogeneous, when the data stored across the computers follows the same distribution; and heterogeneous, when the distributions are different.
In the homogeneous setting, and motivated by the problem of empirical risk minimisation, we consider the learning performance of a simple decentralised algorithm: Distributed Gradient Descent. Specifically, we demonstrate that guarantees on learning performance can be achieved through implicit regularisation alongside, in the case of non-parametric regression, a linear speed up in computational runtime for any network topology provided computers have a sufficient amount of data. In contrast, prior work has focused on optimisation performance through the more general consensus optimisation framework, which does not encode the finer statistical structure behind the scenes. More precisely, we demonstrate that this structure can be leveraged to both: allow model complexity to be controlled implicitly through algorithmic parameters; and that the information held by agents can be similar owing the phenomena of statistical concentration.
In the heterogeneous case a setting motivated by hyperspectral unmixing is considered. Specifically, we consider simultaneously recovering a collection of sparse signals (associated to agents), that are related in a manner reflecting the network topology. In short, the differences in the underlying distributions are encoded through a total variation penalty reflecting the network. Our approach then yields sample complexity savings over group lasso style methods when the signals are sufficiently related.

Keywords: Distributed Machine Learning
Machine Learning
Implicit Regularisation
Statistical Learning Theory
Gradient Descent
Rational synthesis of nanoparticle-MWCNT hybrid nanostructures through non-covalent interactions with organic polymers

The synthesis of hybrid nanostructures comprised by CNTs and nanoparticles is a promising field of research due to their potential applications in catalysis, energy storage, energy generation and biomedical technologies. However, the field lacks of synthetic guidelines for the rational design of hybrid nanostructures. This Thesis aims to stablish synthetic guidelines that consider the forces involved during the synthesis of iron oxide nanoparticle-CNT hybrids where polymers are used to mediate the interactions between the nanomaterials.
The functionalisation of MWCNTs with polystyrene is studied as the first level of hierarchy representing the polymer-MWCNT interactions. Non-covalent methods were found the most effective way to create polystyrene functionalised MWCNTs. It was found that the solvent used during the functionalisation was the parameter that had a higher effect in the amount of polystyrene found in the MWCNTs. The surface energy solubility parameter theories were proposed as a predictive synthetic model for the design of polymer functionalised MWCNTs. The predictions of the model were compared with the amount of polystyrene found in the functionalised MWCNTs synthesised in different solvents, finding good agreement between the predictions and the experimental evidence.
The next level of nanostructural hierarchy was addressed by studying the synthesis of polystyrene coated iron oxide nanoparticle-CNT hybrids. The solvent was found to play a key factor in the amount of polystyrene coated iron oxide nanoparticles found in the hybrid structures. The surface energy based solubility parameter theory was used to understand the amount of iron oxide nanoparticles found in the hybrids synthesised in different solvents, showing a better agreement with the experimental results than other parameters previously highlighted in the literature.
The results and ideas proposed in this Thesis will contribute to the future development of the rational synthesis of nanoparticle-CNT hybrid structures.

Keywords: Hybrid nanostructures
Nanomaterials
Carbon nanotube chemistry
Nanoparticles
Hierarchical structures
Carbon nanotubes
Advisor: Grobert, N
Porfyrakis, K
On the evolution of the lunar magma ocean

The Earth and the Moon are observed to be almost indistinguishable over a range of refractory isotopes systems. This thesis aims to test the hypothesis that the lunar magma ocean (LMO) possessed the same elemental composition as that of the terrestrial mantle. In particular, I explore whether the LMO’s differentiation would result in liquid and crystal phases that can reproduce the Apollo observations of the lunar surface. To achieve this, I have conducted a detailed series of experiments which track the evolution of a hypothetical lunar magma ocean of terrestrial mantle composition. I have broken the differentiation of the LMO into discrete steps, with the bulk composition of the next step taken as the melt composition of the previous step. The final experimental liquid, representing ∼98% crystallisation of the LMO, is highly enriched in Fe (>30 wt.%) and Ti (∼3 wt.%). To explore the petrogenesis of the mare basalts and the Ferroan Anorthosite Suite (FAS), I have simulated the remelting of the lunar cumulate mantle using the MELTS program. By recombining experimental phases and melts in different proportions, I am able to prove that the Apollo observations are compatible with a LMO of terrestrial mantle composition. The mafic crystals present in the ferroan anorthosite suite are best matched to experimentally produced crystals rather than melt, indicating inefficient flotation rather than trapped melt has contributed to the ferroan anorthosite suite.
Mineral/melt Rare Earth element (REE) partitioning occurring throughout the evolution of the lunar magma ocean has been experimentally determined, and predict heavy REE depletion of final liquids, due to high-temperature pyroxene crystallisation. Consequently, the ’bow shaped’ trend witnessed in the mare basalts results from a lunar mantle possessing pyroxene enriched in heavy REE and a light REE enriched KREEP basalt. I explore the implications of different compositions on the lunar moment of inertia, finding that an overturn of the lunar mantle is more significant than any conceivable change in composition.

Keywords: Lunar
Moon
Mare Basalts
Magma Ocean
Geology
Ferroan Anorthosite Suite
Experimental Petrology
Rare Earth Elements
Advisor: Wade, J
Bernard , W