VictorJuiz/thesis huggingface dataset:
Fabrication of High Temperature Superconducting Composites for Microwave Applications

This thesis describes the fabrication of high temperature superconducting (HTS) composites synthesised by casting and 3-D printing techniques for a variety of potential applications such as microwave devices and metamaterials. The fabrication of metamaterials, where electromagnetic (EM) waves are manipulated by varying the effective dielectric constant (εeff) and static magnetic permeability (μeff) in 3- dimensions, is a major area of research worldwide. One approach to synthesising HTS composites with a controllable spatial distribution of electromagnetic properties is the synthesis of polymer composites comprising of multiple volume fractions of superconducting particles, which results in temperature-dependent composite materials.
YBa2Cu3O7 (YBCO-123) superconducting powder was used as filler in the HTS composites. The effect of particle sizes and the non-superconducting Y2BaCu2O5 (YBCO-211) phase on the magnetisation properties of the YBCO filler have been analysed using a SQUID magnetometer. The magnetisation analyses on two types of YBCO fillers proved that YBCO powder ground from top seeded melt growth (TSMG) YBCO bulks with median particle size, d50 = 59 μm possesses stronger diamagnetic properties at 77 K compared to commercially available YBCO powder with a size of d50 = 5 μm. The melt-grown YBCO powder also possesses an irreversible component to the magnetisation owing to flux trapping by the YBCO-211 phase.
A custom-made polytetrafluoroethylene (PTFE) mould was designed and fabricated for the purpose of synthesising HTS composites via casting. The EM properties of the cast HTS composites were measured at room temperature and 77 K using a Vector Network Analyzer. The EM properties of these HTS composites are correlated with the homogeneity and density of YBCO particle distributions in the polymer matrix measured using scanning electron microscopy (SEM). It has been shown that the εeff values of the HTS composites were enhanced with increasing volume fraction of YBCO filler at both temperatures. A large drop of μeff values with volume fraction is observed at 77 K, owing to the diamagnetic response of the superconducting particles. Thus the refractive index of the composites could be controlled by both the volume fraction of YBCO filler and temperature.
In order to realise spatial variations in EM properties, a process has been developed for the fabrication of HTS composites via 3-D printing. The extrusion process was optimised to produce 20% YBCO loaded acrylonitrile butadiene styrene (ABS) feedstock filaments. Finer YBCO filler (𝑑50 = 20 𝜇𝑚) was used to print more intricate 3-D structures such as an anisotropic material and split-ring resonators, but the EM properties were suppressed, suggesting a particle size limitation of the 3-D printing. By contrast, YBCO/ABS composites have been printed with good control of YBCO volume fraction, and good agreement with the cast HTS composites at similar volume fraction of εeff = 5.1 and μeff,77K𝐾 = 0.82 at 77 K achieved.

Advisor: Grovenor, C
Speller, S
Scalable inference and private co-training for Gaussian processes

Two principal problems are pursued in this thesis: that of scaling inference for Gaussian process regression to very large numbers of data points, and that of differentially private co-training between multiple Gaussian processes with distinct private views of the data.
The first chapter acts as an introduction to Bayesian nonparametric regression and standard techniques for performing scalable inference and differentially private communication with Gaussian Processes.
The second chapter explores the use of Tucker decomposition and Kronecker structure of variational distributions in order to use very large numbers of inducing points for scalable variational Gaussian processes. The methods use a massive number of gridded inducing points, enabling more expansive variational approximations, but the computational cost of the methods developed scales sublinearly with m, the number of inducing points used. Computational experiments are performed and compared with standard variational Gaussian processes, and the new method is demonstrated to be more efficient for data sets of moderate dimensionality.
The third chapter pursues the use of stochastic algorithms for evaluating unbiased approximations to the gradients of the lower bound for a scalable variational Gaussian process. Consequently, O(m2) inference is possible, in contrast to the O(m3) inference for a standard variational Gaussian process. Systematic computational experiments are performed and compared with a standard variational Gaussian process, with mixed results.
The fourth chapter considers the problem of preserving privacy when engaging in co-training for regression with multiple Gaussian processes, each trained on different sets of covariates or “views”. Information is exchanged between views with predictions on unlabelled data: various methods are introduced to incorporate the predictive distributions, and mechanisms for formally preserving the differential privacy of the response variable are included. Analogies are drawn between the Kronecker product across dimensions of the second chapter and the fourth chapter’s co-training between views. Experiments are performed on simulated and real data, and the results are presented and analysed. It is shown that differentially private exchange of information between views via predictions on unlabelled data can improve the performance of the models.
The fifth chapter concludes.

Advisor: Holmes, C
Autophagy-dependent generation of free fatty acids is essential for normal neutrophil differentiation by guiding an energy-metabolic switch

Neutrophils are critical and short lived mediators of innate immunity that require constant replenishment. Their differentiation in the bone marrow requires extensive cytoplasmic and nuclear remodeling, but the processes governing these energy-consuming changes are unknown. While previous studies show that autophagy is required for differentiation of other blood cell lineages, its function during granulopoiesis has remained elusive. Autophagy was described as a critical process in HSC differentiation and in memory- and regulatory T cells, where it prevents excessive glycolysis and maintains lipid metabolic homeostasis. In the myeloid lineage, an essential role for autophagy is to prevent pro-inflammatory macrophage polarization and to limit glycolytic metabolism of acute myeloid leukemia. While these studies provide robust in vivo evidence for the relevance of autophagy in the differentiation of hematopoietic and immune cells, the targets and mechanisms of autophagy remain elusive. Here, we show that metabolism and autophagy are developmentally programmed and essential for neutrophil differentiation in vivo. Atg7 -deficient neutrophil precursors had increased glycolytic activity but impaired mitochondrial respiration, decreased ATP production and accumulated lipid droplets. Inhibiting autophagy-mediated lipid degradation or fatty acid oxidation alone was sufficient to cause defective differentiation, while administration of fatty acids or pyruvate for mitochondrial respiration rescued differentiation in autophagy deficient neutrophil precursors. Together, we show that autophagy-mediated lipolysis provides free fatty acids to support a mitochondrial respiration pathway essential to neutrophil differentiation. Evidence presented here also contributed to studies on autophagy-mediated metabolic homeostasis in HSCs, Treg cells and myeloid leukemia, suggesting that this pathway may act broadly during differentiation.

Advisor: Simon, A
Jacobsen, S
Gentlemen of leisure or vital professionals? The officer establishment of the British army, 1689-1739

This thesis argues that the officer establishment of the British Army experienced considerable professional, administrative and social change from its expansion in 1689 to the outbreak of war in 1739. In the intervening fifty year period, the British army and the officers who led it experienced alternate periods of prolonged war and peace. This led to the retention and dissemination of administrative practices, gentlemanly behaviours and professional competencies that enabled officers to remain motivated and dedicated to military service, despite multiple factors that hindered their ambitions and reduced their career prospects. This development was not a series of comprehensive reforms, but rather ad hoc measures which took effect through the efforts of commanding officers, the will of the monarch and the administrative power of the War Office. These changes occurred within the existing military system, stretching its capacity to satisfy multiple interests to its limit, and resulting in the prioritisation of certain consideration over others. Using a greater quantity and range of archival material than previous historiography, the thesis adopts several historical approaches towards their interpretation, from institutional and military history, to cultural and political history. This offers new perspectives and in-depth analysis to challenge some arguments made about army officers during this period, and refinements to others. It contributes to our understanding of the late seventeenth and eighteenth century army by rethinking the martial ethos of the officer establishment, and its impact on the officer establishment’s capabilities, behaviour and relationship with the crown.

Keywords: Eighteenth Century
Army administration
British Army
Military Experience
Professionalization
Advisor: Charters, E
Smith, H
Structural investigations of peptide folding and unfolding in solution

Proteins are the essential biological working molecules in all living beings. Their function depends on their ability to adopt a specific three-dimensional structure in aqueous solution. The mechanism of this folding process, and conversely the loss of protein structure, unfolding, is still not well understood, especially on the atomic scale where these interactions occur in vivo. In this thesis, the structures of small model peptides have been investigated in aqueous solutions in order to understand how water, urea and other co-solutes influence protein folding and unfolding. Using a combination of neutron diffraction enhanced by isotopic substitution and computer simulations, it was found that urea, generally at any probed concentration, decreases ionic interactions with the peptides in solution. When the peptide backbone is solvent accessible, urea interacts directly with the polar peptide backbone and replaces water molecules at higher urea concentrations. Further, the results indicate an ambiguous in uence of water on peptide folding vs. conformational stability. The formation of β-turn like structures, and possibly intra-peptide hydrogen bonds in general, appears to be dependent on a specific backbone hydration pattern, facilitated by the local amino acid sequence. Conversely, hydrophobic residues in folded protein structures are particularly sensitive, in terms of conformation and hydration, towards an increased peptide backbone hydration.

Advisor: McLain, S
Redfield, C
Inflammation and colorectal cancer: elucidation of the cellular and molecular mechanisms by which interleukin 22 contributes to the development and progression of colorectal cancer

Colorectal cancer (CRC) is a molecularly heterogeneous disease driven by the complex interplay between genetic factors, such as oncogenic mutations, and microenvironmental factors, such as aberrant immunity. Notably, interleukin 22 (IL- 22), which plays a critical role in intestinal epithelial repair, promotes CRC progression in murine models of both colitis-associated and sporadic CRC. However, the phenotypes associated with IL-22/IL-22 receptor expression in human CRC remain uncharacterized and the molecular mechanisms of IL-22-dependent tumourigenesis are not understood. Thus the primary aim of this study was to understand the mechanisms by which IL-22 contributes to the development and progression of human colorectal cancer.
Specific driving mutations in human CRC critically influence the impact of the IL-22 pathway on disease progression. The KRAS oncogene is mutated in roughly 40% of colorectal cancers and carries a minor adverse prognostic impact. However, using independent training and validation cohorts in tumour transcriptomic datasets totalling 1820 patients, we identified that in patients with high tumoural expression of either or both subunits of the heterodimeric IL-22 receptor (IL22RA1, IL10RB), KRAS mutation markedly worsens prognosis. Using a panel of CRC cell lines and primary human organoids, we confirmed that this prognostic association is due to a functional interaction between IL-22 and mutant KRAS by observing that IL-22 enhances chemoresistance, 3-dimensional clonogenicity, and proliferation specifically in CRC cells with both high IL-22 receptor levels and KRAS mutations. Taking unbiased RNA-sequencing and proteomic approaches, we identified non-cell autonomous and cell autonomous pathways by which IL-22 may interact with KRAS to promote malignancy. IL-22 enhanced ELR+ CXC chemokine expression, which may condition a tumour-promoting immune microenvironment, and induced the Myc pathway, which may augment proliferation and glycolytic flux, in KRAS mutant cells.
Collectively, this work has revealed that an IL-22 signal is interpreted differently in the presence or absence of mutant KRAS. Our data points toward a method to identify a subset of poor prognosis IL-22 receptor-high, KRAS mutant CRC patients and we hypothesise that blockade of the IL-22 pathway in these patients may have therapeutic benefit.

Advisor: Powrie, F
Representing the dynasty in Flavian Rome: the case of Josephus' "Jewish War"

This thesis investigates the problem of contemporary historiography and regime representation in Flavian Rome through a close study of a text not usually read for such purposes but which has obvious promise for a study of this theme, the Jewish War of Flavius Josephus. Having surveyed the evolution of our conception of Josephus’ relationship to Flavian power, taken a broad account of issues of political expression and regime representation in Flavian Rome outside Josephus and examined questions relating to the structure and date of the work, I will provide a series of thematically-focused readings of the three senior members of the Flavian family, Vespasian, Titus and Domitian, as represented by their contemporary and client Josephus. Key topics to be explored include the level of independence of Josephus’ vision, his work’s relationship to how the regime is depicted in other contemporary sources, how Josephus makes the Flavians serve his own agenda (which is distinct from the heavy focus of most previous scholarship on how Josephus served their agenda), and the viability and usefulness of certain types of reading practices relating to figured critique which have recently become influential in Josephan scholarship. The thesis offers a new approach to Josephus’ relationship to the Flavian Dynasty and sheds new light on contemporary historiography and political expression in the Early Principate.

Keywords: Roman historiography
Flavian dynasty
Josephus
Advisor: Goodman, M
The rationality of rationing: a rhetorical policy analysis of deliberations about resource allocation in the NHS

The rationing of health care is one of the most politically sensitive and challenging issues facing policymakers today. Despite long-standing debate about how we should or might make rationing decisions, we still know surprisingly little about how such decisions are accomplished in practice.
This thesis opens up the ‘black box’ of rationing practices. It explores theoretically and empirically what it means for rationing decisions to be made rationally. My work challenges dominant conceptualisations of rationality in health policy, suggesting that rationing is inevitably and inextricably as much a social practice of deliberation and judgement, involving experiential knowledge, emotional engagement, and what Aristotle called ‘phronesis’, as a technical process of applying research evidence and ethical principles, and following fair processes.
I locate my research in the emerging fields of interpretive policy analysis and linguistic ethnography, and draw on sensitising concepts from rhetorical theory and Bakhtinian scholars to develop a novel approach to rhetorical policy analysis. My study is based on ethnographic observation of the deliberations of one priorities forum and three individual funding request panels of local NHS commissioning organisations. I explore close up the role of language and meaning making in these rationing groups, and demonstrate the ways in which they create their own ‘interpretive communities’ within which rationality is locally constructed.
My findings focus on four aspects of practice I identify as dilemmatic: the legitimacy of affordability as a guiding value of NHS health care, the emotionality of decision-making, the construction of some treatments as ‘low priority’, and the role of lay people and ordinary knowledge in deliberations. My analysis exposes the ideological work of rationing discourse in defining the boundaries of what the NHS will fund, and shifting notions of entitlement to health care.

Advisor: Greenhalgh, P
Shaw, S
Reading the gallery: portraits and texts in the mid- to late nineteenth century

The Victorians saw more portraits than any generation before them. While the eighteenth century has been named 'the age of portraiture', portraits pervaded nineteenth-century society like never before. With the invention of photography, coupled with technological advancements in low-cost printing methods, the medium in which faces could be recorded was revolutionised, the classes of society that could afford to be immortalised expanded, and the spaces in which portraits were seen proliferated. These spaces included the public gallery, photography studio shop windows, and personal photograph albums. They also included the art periodical, biography, fiction, and poetry as the experience of portraiture became distinctly textual as well as visual.
This thesis draws upon art history alongside literary, museum, and material studies to explore the creative exchange that developed between portrait viewership and reading practices in the mid- to late nineteenth century. Taking the establishment of the National Portrait Gallery in 1856 as its starting point, the thesis tracks the changing idea of the portrait gallery through its literary reception. It takes the portrait gallery to mean the physical space in which portraits were exhibited, and the conceptual idea of collecting, arranging, and interacting with portraits that permeated into the literary world. By focussing on the work of Edmund Gosse, Walter Pater, Thomas Hardy, and Vernon Lee, the thesis forms a 'gallery' of nineteenth-century tastemakers, each of whom looked to the democratic art of portraiture to reflect upon their literary art.
How did portraits and texts interact in the mid- to late nineteenth century? In what ways did writers adapt the conventions of portraiture and the portrait gallery for the written text? This thesis seeks to answer these questions and provide new narratives about the complex relationship between the visual and the verbal in nineteenth-century culture. It observes the Victorian 'culture of art' with a more focussed eye to illuminate how the conditions of viewing, circulating, and collecting portraits specific to the period allowed the portrait gallery to serve as a particularly compelling arena for the literary imagination. Gosse, Pater, Hardy, and Lee tested the inherent limitations of portraiture as an art of imitation to realise its imaginative capacity for communicating with close and distant, contemporary and historic figures. They recognised that writing offered a valuable way of constructing the affective conversations that could be had with – and the stories that could be told about – portraits and portrait collections. With the proliferation of portraits came the problem and the opportunity of organising them.

Keywords: Portraiture
Vernon Lee
Decadent
Gallery
Museum
Photography
Thomas Hardy
Walter Pater
Collecting
Edmund Gosse
National Portrait Gallery
Advisor: Mendelssohn, M
West, S
Hedgehog-interacting protein (Hhip) as a candidate Foxn1 target in the thymus

The thymus is a primary lymphoid organ that supports the development of functional T cells through its unique stromal architecture. The most important and abundant component of this microenvironment are thymic epithelial cells, or TECs. TEC development, function and maintenance are critically dependent on the expression of the master transcription factor Foxn1. The Hedgehog-Interacting Protein (Hhip) was identified as a novel candidate target of Foxn1-mediated gene expression. Hhip is an inhibitor of Hedgehog (Hh) signalling, an embryonic developmental pathway which is also vital for normal T cell development.
I first provided evidence that Foxn1 indirectly modulated the Hh signalling pathway via hhip. To identify a role for Hhip in thymus biology, I investigated the consequences of a constitutive deficiency for hhip expression in embryonic and neonatal mice, and demonstrated that loss of hhip resulted in an upregulation of Hh signalling via the coreceptors Gas1 and Boc, affecting the relative frequencies of cortical and medullary TECs in a dose-dependent manner and favouring medullary TEC development. I also generated a novel transgenic mouse model with a targeted loss of hhip in Foxn1-expressing cells, to specifically delineate the role of Hhip in TECs. This approach additionally circumvented the limitation of neonatal lethality in constitutive hhip-deficient mice. TEC-targeted loss of hhip expression not only impacted TEC sublineage decisions, but also affected the ability of TECs to perform positive thymocyte selection, resulting in the generation of T cells with reduced TCR signal strength which were less responsive to mitogenic stimuli. In aggregate, the experimental data here presents the first evidence that Hhip plays an important role in regulating TEC differentiation and function.

Advisor: Hollander, G
Bassett, A