VictorJuiz/thesis huggingface dataset:
The Chabauty-Kim method for relative completions

In this thesis we develop a Chabauty--Kim theory for the relative completion of motivic fundamental groups, including Selmer stacks and moduli spaces of admissible torsors for the relative completion of the de Rham fundamental group. On one hand, this work generalizes results of Kim (and therefore Chabauty) in the unipotent case by adding a reductive quotient of the fundamental group. From this perspective, the addition of a reductive part allows one to apply Chabauty-type methods to fundamental groups with trivial unipotent completion, such as SL2(ℤ).
On the other hand, the unipotent part provides a natural extension of the recent work of Lawrence and Venkatesh. We show that their concern with the centralizer of Frobenius goes away as one moves up the unipotent tower and away from the reductive world of flag varieties and the Gauss--Manin connection. One is tempted to hope that the relative completion will provide a unified proof of Mordell's conjecture that takes advantage of the two methods. Toward this end, we apply our work to the Legendre family on the projective line minus three points, a particular example where the method of Lawrence and Venkatesh fails.

Keywords: anabelian
chabauty
arithmetic geometry
Number theory
fundamental group
motive
rational point
Advisor: Kim, M
The ceramic trade between China and Southeast Asia during the Song Dynasty (960-1279)

This thesis studies the shipwrecks in the South China Sea and their recovered artefacts to discuss the ceramic trade between South China and Southeast Asia during the Song dynasty (960-1279). This period is of particular interest because it was when Chinese ceramics started to be exported in bulk and make its name around the world. And shipwrecks in the South China Sea are the best materials to uncover the first leg of the long-distance trans-Asian trade route that led from China to the Mediterranean. Although there have been cases studies regarding one or several shipwrecks, thorough research that examines the overall findings of this period and addresses not only the products but also the trade network and the market of the products is somewhat lacking. To this aim, this thesis attempts to address the central questions as to how the trade was conducted and by whom, what are the changes of the exported ceramic types during this period and why, and whether there were vessel forms and decoration made to cater to the need of the Southeast Asian market. In doing so, the thesis provides a broader picture of the ceramic trade during the Song period and manages to extract some information on the human level.
First, I argue that in the tenth century, as represented by the Intan and Cirebon shipwreck, the trade of major cargo was organized by a few people or a single authority possibly the state government and headed towards limited destinations. During the later period, as the case studies of the Nanhai No.1 and Quanzhou Bay wreck show, the sea-borne journey was mainly a profit-oriented peddler trade undertaken by individual merchants whose identities were not confined to traders with an official background or abundant assets, but also included those of lower social status such as sailor and small merchants. Secondly, through the systematic comparison between the findings on the wrecks and those from domestic sites, especially kiln sites, the provenance of most ceramic cargo is assigned and the shift of production from Zhejiang to Guangdong and then Fujian province is revealed. The reason behind the first shift, I argue was due to the change of the nature of maritime commerce, from being part of a tributary system to profit-orientated, from state-monopoly to being mainly conducted by private shipping. As for the shift of trade to Fujian province, it was driven by merchants based on the products and regional manufacturing industrial competitiveness. By examining a large number of published materials, it is demonstrated that effort was made to cater to the need of the Southeast Asian market. Nevertheless, the detailed analysis of the recovered ceramics indicates high uniformity among ceramic cargos of contemporaneous shipwrecks despite the differences in the targeted markets. I suggest that the ceramic trade between South China and Southeast Asia during the Song period was mainly dominated by the seller instead of the buyer.

Keywords: Southeast Asia
maritime trade
the Song Dynasty
exported ceramics
Advisor: Lee-Thorp, J
The representation and processing of vowel duration as a perceptual cue for word-final voicing in native and non-native English

The relationship between vowel duration and word-final voicing in English is well attested. In a minimal pair, contrasting in word-final obstruents, the production of a longer vowel precedes the voiced obstruent (for example [bæd] bad) relative to the voiceless obstruent (for example [bæt] bat). The research presented here focuses on the underlying representation of vowel length, and the manner in which listeners process this representation to characterise word-final voicing. A total of five experiments were run examining a range of both recorded and synthesised monophthongs and diphthongs (/æ/, /eɪ/, /əʊ/, /aɪ/), thereby assessing the representation of both underlyingly single and bimoriac vowels.
In two of the five experiments presented, data obtained from native and non-native English speakers are compared. The aim here is to assess how the representation and processing of this fine-grained perceptual cue differs for L2 English speakers for whom this positional contrast does not exist in the surface form of their native phonology. Here, we consider German wherein the voicing contrast is neutralised word-finally, and only voiceless word-final obstruents are permitted in the surface form. Lexical status is also considered, alongside the extent to which lexical and acoustic information interact when there a mismatch between vowel duration and voicing. Most notably, results from a series of forced choice identification tasks and reaction time data obtained from a lexical decision task with fragment priming consistently support the notion that vowel duration acts as a primary perceptual cue for word-final voicing in native English speakers. For non- native speakers, an increased sensitivity to this perceptual cue is present in speakers who have had more exposure to spoken English, though this tendency remains governed by native phonology. Specifically, where an underlying voicing contrast does exist in German, listeners are primarily guided by their L1 phonology; perceiving a majority of voiceless responses. However, where an underlying voicing contrast does not exist in German, participants are guided by L2 phonology. Here, a lexical effect is found wherein German participants who have received less exposure to spoken English do not adhere to this tendency for nonwords. In the case of production, participants adhere to their L1 phonology for nonwords containing word-final sounds in which there is no underlying voicing contrast in German, regardless of the amount of exposure to spoken English received by the speakers.

Keywords: psycholinguistics
phonology
German phonetics
English phonology
Featurally Underspecified Lexicon
phonetics
German phonology
speech perception
vowel duration
duration
voicing
linguistics
FUL
word-final voicing
English phonetics
Advisor: Lahiri, A
Data driven approach to robust pricing, hedging and risk management and its dynamics in time

Model-independent mathematical finance is a relatively young research field, which aims to quantify Knightian uncertainty on the choice of pricing models. This thesis extends the existing framework to a setting, which is dynamic in time and takes new sources of information (e.g. new statistical estimates or changed market prices) into account as soon as they emerge. In this context, new connections to the fields of of optimal transport on the one hand and statistics on the other are established, with the ultimate goal to develop a universal toolbox for the implementation of robust and time-consistent trading strategies and risk assessment.

Keywords: Robustness
(Robust) Statistics
Superhedging price
Wasserstein distance
(Martingale) Optimal Transport
Derivatives hedging
Neural networks
Risk measures
Mathematical Finance
Pricing-hedging duality
Fundamental Theorem of Asset pricing
Derivatives pricing
Statistical estimation
Advisor: Obloj, JK
Aesthetic ecclesiology: an anglican theological response to the work of Charles Taylor on the secular

In this thesis I consider the work of Charles Taylor from a theological perspective, specifically relating this consideration to the topic of ecclesiology. I argue that Taylor and related thinkers such as John Milbank and Rowan Williams point toward what I call an “Aesthetic Ecclesiology”, that is an ecclesiology that values highly and utilizes the aesthetic in its self-understanding and practice.
I begin with the observation that Taylor’s work provides an account of the breakdown in Modernity of the conceptual relationship of the immanent and the transcendent. I add to Taylor’s account that of John Milbank and the Radical Orthodoxy movement, arguing that Milbank’s work is largely complementary to Taylor’s, and that, whereas Taylor’s genealogy operates on a largely historico-cultural level, Milbank’s takes account of high-level elite movements within the realms of theology and philosophy. The final chapter utilizes the theology and ecclesiology of Rowan Williams, whose work is seen as, again, complementary to what has gone before, adding to it by providing first-hand priestly and episcopal reflection in addition to an emphasis on the Church as rooted in history and, at points, taken to its limits.
I conclude that certain important ecclesiological implications follow from the observation of the illegitimate breakdown of the conceptual connection of the immanent and the transcendent: firstly, this observation implies that the aesthetic may be a more theologically rich category than it is often given credit for. It is neither an irrelevance nor necessarily idolatrous but can be a legitimate conduit for the presence of the divine. It is argued therefore that the reconnection of the transcendent and the immanent coheres well with an understanding of the Church that takes into account the material reality of the sacraments and the Church’s status as historical, global and eschatological. Secondly, the aesthetic provides the Church with a powerful apologetic: beauty cannot be reduced to the presuppositions of secular materialism, and so must be accounted for by recourse to transcendent categories.

Keywords: Beauty
Aesthetics
Ecclesiology
Christianity
Secularism
Anglicanism
Advisor: Ward, G
Hanvey, J
Zachhuber, J
The legacy of polders: Diagnosing complex flooding processes and adaptation options in the coastal region of Bangladesh

Polders (enclosed coastal embankments) are often constructed to protect river and coastal floodplains in deltas. In Bangladesh, a total of 139 polders have been constructed between the 1960s and 1980s to safeguard agricultural lands from potential damage due to tidal floods, storm surge floods, and salinity intrusion. Whilst such flood control measures reduce the probability of flooding, they have had complex impacts on geomorphological and hydrological processes with consequence for human wellbeing. This legacy of interventions in the coastal system and subsequent human adaptations, now makes decision making even more challenging at a time of increasing environmental pressures.
This thesis analyses historical floods in the coastal zone in Bangladesh, diagnosing whether the floods were attributable to monsoonal precipitation (pluvial flooding), high upstream river discharge into the tidal delta (fluvio-tidal flooding), or cyclone-induced storm surges. It quantifies polders’ effectiveness by modelling different forms of inundation to estimate what flooding might have been had the polders not been constructed.
Considering the societal impacts of flooding, the effects of changing land-use and flood risk on poverty are quantified. The results answer the questions of (i) how the pattern of land use/land cover (LULC) change influences flood risk at present and continue to do so in the future; (ii) how LULC change and flood risk impact poverty spatially.
The last section of the thesis focuses on estimating the impacts of potential Tidal River Management (TRM) on elevating the floodplains and reducing the annual probability of flooding. It identifies suitable TRM sites to model sediment deposition in those areas. The potential impact of TRM on flooding is investigated by comparing flood susceptibility ‘before and after’ the implementation of TRM.
By analysing complex coastal flood processes and adaptation options spatially and quantitatively, this thesis provides new evidence to the effectiveness of the past (polders), and potential future (TRM) adaptation options. It also presents a new approach to flood risk estimation, considering the societal impacts of flooding. The results of this thesis could be of importance both in research and practice for making scientifically informed decisions on coastal flood risk management, particularly in Bangladesh.

Keywords: Flood adaptation
Polder
Flood hazard, susceptibility, and risk
Bangladesh
Coastal flooding
Land use change
Tidal River Management
Advisor: Hall, J
A constructive theology of prayer, drawing on the work of Hans Urs von Balthasar

In this thesis I provide a constructive theology of prayer drawing on the work of Hans Urs von Balthasar (1905-1988). I do this by exploring the Trinitarian, Christological, ecclesial, anthropological, and eschatological dimensions of prayer in Balthasar’s theology, and showing how these combine to give an account of prayer’s proper theological scope and purpose. I argue that it is frequently in connection to the topic of prayer that Balthasar’s coherence and creativity as a theologian are most apparent. My approach is intended to demonstrate the centrality of prayer to Balthasar’s entire theological system, and to do so in a way which itself constitutes an exercise in Catholic systematics. I show that for Balthasar prayer is a central aspect of Christian existence, with its foundation in the eternal Trinitarian life and its end in the eschatological future of the world. In this way prayer has a certain shape or rhythm which Balthasar’s theology helps to clarify. There is furthermore a critical aspect of prayer which is underdeveloped in Balthasar but which I show to have significant dialogical potential with contemporary accounts of parrhesia since Foucault. Prior to taking up the various questions related to prayer, I establish a method of proceeding through Balthasar’s sprawling oeuvre (and the similarly vast secondary literature) by arguing for three “categories” of texts in Balthasar’s writings and, separately, three “waves” of Balthasar readers. These models are intended to be resources for future students of Balthasar, regardless of their particular research interests. Altogether, then, this thesis substantiates the claims that prayer is both a central aspect of and a topic for an engaged systematics, while showing the ways in which Balthasar’s particular understanding of the relationship between theology and prayer is still relevant to the task of theology today.

Keywords: parrhesia
prayer
Balthasar
Advisor: Hanvey, J
Ward, G
Re-inhabiting modernism: embodied cognition in German literature and thought 1910-1934

This thesis brings five German modernist texts into dialogue with contemporary cognitive studies. In doing so, it opens up a space from which to explore an often-neglected aspect of German modernist texts, namely their exploration of how one can re-situate oneself in unfamiliar environments. Rather than emphasising the alienation and isolation that these texts explore regarding the modern urban environment, this dialogue helps us focus on the more dynamic moments of use, responsiveness, cooperation, and coordination also at the heart of these explorations. At the same time, the modernist period, as a dynamic and often overwhelming time of socio-political and material change and upheaval, also asks us to shift our focus, in contemporary cognitive studies, away from smooth coping, that is, the moments in which things go well and easy. Infusing cognitive studies with the existential questions asked by these texts helps us explore not only the ways in which we react to the socio-material environment’s resistance and frustration of our everyday comportments, but also the ways in which we can come to be responsive to, and re-situate ourselves in, such unfamiliar territory. Through this dialogue, then, I develop an answer to the problem of the recalcitrance of an unfamiliar environment, a problem which is increasingly relevant in a global, uproot-ed, and dynamic world. It submits a task-oriented approach to unfamiliarity, one that is affectively responsive to the affordances of the environment, especially those of other people, a responsiveness that can be achieved, somewhat counter-intuitively, through the re-animating warmth of the familiar other.

Keywords: Skill
Habit
Responsiveness
Embodied Cognition
German thought
Modernism
German literature
Advisor: Morgan, B
Isochoric generation and spectroscopic diagnosis of high energy-density systems

Advances in both optical laser and X-ray Free Electron Laser (XFEL) facilities have extended the regimes accessible in laser targets. Petawatt lasers such as Orion at AWE can be routinely used to drive targets to extreme conditions of multi-keV temperatures. Isochoric heating with an XFEL to temperatures of 100’s of eV has been demonstrated and well described on prototypical metals and low-Z mixtures, and the bright, tunable x-ray source is often used as a probe in Warm Dense Matter (WDM) and High Energy-Density (HED) studies. X-ray diagnostics are often used to characterise the conditions present in such a laser target, with stringent demands on collection efficiency to yield significance in signal/noise in order to characterise systems with potentially large spatio-temporal gradients.
This thesis describes a set of experiments to isochorically generate and characterise WDM and HED systems relevant to astrophysical plasmas and Inertial Confinement Fusion. The focus of this work is on using measured X-ray Emission Spectroscopy or Resonant Inelastic X-ray Scattering (RIXS) spectra to bound the conditions present in the laser target, and using Single Photon Counting informed techniques to maximise the signal/noise in recovered spectra. Accurate accounting of the single photon response of x-ray detectors is used to detail the absolute value and error on recovered spectral intensity, and from that to inferred plasma parameters. The particular systems considered in this work are nanowire targets irradiated at relativistic intensities, RIXS measurements of warm-dense nickel, and nano-focused XFEL heating of solid density iron.
The recovered plasma conditions mapped from experimental data are shown to correspond well to Particle-In-Cell and Density Functional Theory, benchmarking simulation capacity and offering insights into factors affecting the target’s response to laser drive. The results and methods presented here could inform and complement future efforts to investigate warm- and hot-dense systems, as a diagnostic capability or elucidating a navigable route toward ultra-HED systems.

Keywords: single photon counting
xfel
high power lasers
resonant inelastic x-ray scattering
High energy density
x-ray spectroscopy
nanowires
x-ray free electron lasers
Advisor: Vinko, S
More than a principal: A mixed methods exploration of successful high school leadership in the Western Cape, South Africa

School leadership matters. After teachers and teaching, school leadership is the most important determinant of student achievement in school, although there is still uncertainty regarding what successful school leadership is and what successful school leaders do in non-Western contexts. This mixed methods study explores successful high school leadership in South Africa. Specifically, a questionnaire was administered to 38 principals from academically high-achieving schools in a range of socioeconomic contexts throughout the Western Cape, and 14 principals were interviewed. An integrated analysis reveals the paradox of uniqueness and universality of successful school leadership in South Africa, outlining that while there is no single best approach, various similarities exist between successful school leaders and the established international literature. The study finds that successful principals adapt to their context, amalgamate transformational, instructional and distributed leadership styles, set direction, develop people, constantly redesign the school with teaching and learning, and, importantly, strive to make a difference in the lives of others. By shining a light on these characteristics and practices, the study offers theoretical, practical and personal advice to aspiring school leaders.

Keywords: Successful school leadership
South Africa
School leadership
Principal leadership
Advisor: Mayer, D
Religious pluralism in pre- medieval India (600 A.D. – 900 A.D)

A study of post-Gupta literature [including two contemporary plays] and archaeological sources in order to ascertain the extent to which pluralism of religion was present in popular culture, even though the sectarian textual tradition frequently opposed each other as heretical sects. The main hypothesis of the thesis is the existence of variegated sectarian traditions, which coexisted in the public sphere, despite the machinations of the sectarian theologians.

Keywords: Pluralism
Tolerance
Hinduism
Indian religion
Advisor: Minkowski, C
Development of a dual fermion approach to the fcc Hubbard model

We develop a codebase for performing dynamical mean field theory (DMFT) and dual fermion (DF) calculations on the Hubbard model, by modifying, extending, and interfacing several pre-existing open-source codes. This is used to examine the Hubbard model on a face-centered cubic (fcc) lattice, to obtain numerically-exact results at the level of DMFT and investigate the effect of non-local electron correlations within the dual fermion approach.
Our code centres around a modified implementation of the CTHYB quantum Monte Carlo technique used as an impurity solver. We discuss the modifications made, and validate our code by comparing its results to known results in the literature. The DF calculations are obtained by using the CTHYB results as inputs to an extension of the OpenDF code, which we likewise validate by comparison of our results to those of previous authors.
We study the magnetic phase diagram, magnetic susceptibilities, and single-particle dynamics of the Hubbard model on the fcc lattice. Within DMFT a large FM region is found above half-filling, the phase boundary of which is located precisely by susceptibility and magnetisation calculations. A large AFM phase is found around and below half-filling with contributions from instabilities towards the X and W points. Single-particle spectra are obtained using the Maximum Entropy method for a wide range of temperatures and fillings demonstrating how the spectra change as the FM phase boundary is crossed.
The non-local correlations taken into account by the DF approach reduce the critical temperatures of both the FM and AFM regions. Corrections in the FM region are small and strongly suggest that DMFT is able to capture the relevant physics in this region of the phase diagram.
The code developed as part of this project opens the door for further investigations of the Hubbard model on the fcc, and other lattices, across wide ranges of parameter space.

Keywords: magnetism
dual fermion
CT-QMC
DMFT
Advisor: Galpin, M