VictorJuiz/thesis huggingface dataset:
Analysis and design of nickel-based single crystal superalloys

This thesis provides a research into properties of nickel-based single crystal super- alloys. The underlying quantitative relationship between alloy chemistry and the important properties have been studied. To design new grade of single crystal su- peralloys, computational modelling methods have been proposed which build on the findings of composition-microstructure-property relationships.
A physical model for the creep deformation of single crystal superalloys is presented, in which the dependence of the kinetics of creep deformation on alloy chemistry is rationalised. The rate-controlling step is considered to be climb of dislocations at the matrix/particle interfaces and their rate of escape from trapped configurations. The effects of microstructural scale precipitate size, geometry and spacing are also studied. A first order estimate for the rate of creep deformation emerges from the model, which is useful for the purposes of alloy design.
Three new single crystal superalloys have been isolated using theory-based com- putational modelling approaches, termed Alloys-By-Design methods. They are (i) an oxidation-resistant low Re-containing alloy with balanced properties, intended for general-purpose gas turbine applications; (ii) an alloy containing 5.6 wt.% Re and 2.6 wt.% Ru suitable for high performance jet engine applications, and (iii) a cheap, corrosion-resistant alloy for power generation applications. The new alloys have been manufactured using investment casting techniques, and their creep and oxidation behaviour evaluated.
The multicomponent composition space pertinent to the single crystal nickel-based superalloys has been mapped and searched, by using newly developed numerical al- gorithms. This allowed compositions of alloys conferring the microstructures needed for optimal properties to be identified, at a resolution of 0.1 wt.%. Databases have been constructed which contain all appropriate compositions available in these systems. When coupled with composition- and microstructure-dependent property models, the databases can be searched to identify new alloys predicted to exhibit the very best properties or combinations of them.

Keywords: creep
alloy-by-design
superalloys
modelling
Advisor: Reed, R
Feature detection in mammographic image analysis

In modern society, cancer has become one of the most terrifying diseases because of its high and increasing death rate. The disease's deep impact demands extensive research to detect and eradicate it in all its forms. Breast cancer is one of the most common forms of cancer, and approximately one in nine women in the Western world will develop it over the course of their lives. Screening programmes have been shown to reduce the mortality rate, but they introduce an enormous amount of information that must be processed by radiologists on a daily basis.
Computer Aided Diagnosis (CAD) systems aim to assist clinicians in their decision-making process, by acting as a second opinion and helping improve the detection and classification ratios by spotting very difficult and subtle cases. Although the field of cancer detection is rapidly developing and crosses over imaging modalities, X-ray mammography remains the principal tool to detect the first signs of breast cancer in population screening. The advantages and disadvantages of other imaging modalities for breast cancer detection are discussed along with the improvements and difficulties encountered in screening programmes. Remarkable achievements to date in breast CAD are equally presented.
This thesis introduces original results for the detection of features from mammographic image analysis to improve the effectiveness of early cancer screening programmes. The detection of early signs of breast cancer is vital in managing such a fast developing disease with poor survival rates. Some of the earliest signs of cancer in the breast are the clusters of microcalcifications. The proposed method is based on image filtering comprising partial differential equations (PDE) for image enhancement. Subsequently, microcalcifications are segmented using characteristics of the human visual system, based on the superior qualities of the human eye to depict localised changes of intensity and appearance in an image. Parameters are set according to the image characteristics, which makes the method fully automated.
The detection of breast masses in temporal mammographic pairs is also investigated as part of the development of a complete breast cancer detection tool. The design of this latter algorithm is based on the detection sequence used by radiologists in clinical routine. To support the classification of masses into benign or malignant, novel tumour features are introduced. Image normalisation is another key concept discussed in this thesis along with its benefits for cancer detection.

Keywords: curvilinear structures
human visual model
breast cancer
cancer detection
image processing
tumor
medical imaging
microcalcifications
Advisor: Brady, J
Data fusion models for detection of vital-sign deterioration in acutely ill patients

Vital signs can indicate patient deterioration prior to adverse events such as cardiac arrest, emergency admission to the intensive care unit (ICU), or death. However, many adverse events occur in wards outside the ICU where the level of care and the frequency of patient monitoring are lower than in the ICU. This thesis describes models for detection of deterioration in acutely ill patients in two environments: a step-down unit in which patients recovering from an ICU stay are continuously monitored, and a general ward where patients are intermittently monitored following upper gastrointestinal cancer surgery.
Existing data fusion models for classification of vital signs depend on a threshold which defines a “region of normality”. Bradypnoea (low breathing rate) and bradycardia (low heart rate) are relatively rare, and so these two types of abnormalities tend to be misclassified by existing methods. In this thesis, techniques for selecting a threshold are described, such that the classification of vital-sign data is improved. In particular, the proposed approach reduces the misclassification of bradycardia and bradypnoea events, and indicates the type of abnormality associated with the deterioration in a patient’s vital signs.
Patients recovering from upper gastrointestinal (GI) surgery have a high risk of emergency admission to the ICU. At present in the UK, most intermediate and general wards outside the ICU depend on intermittent, manual monitoring using track-and-trigger systems. Both manual and automated patient monitoring systems are reported to have high false alert rates. The models described in this thesis take into account the low monitoring frequency in the upper GI ward, such that the false alert rate is reduced. In addition to accuracy, early detection of deterioration is a highly desirable feature in patient monitoring systems. The models proposed in this thesis generate alerts for patients earlier than the early warning systems which are currently in use in hospitals in the UK. The improvements to existing models proposed in this thesis could be applied to continuous and intermittently acquired vital-sign data from other clinical environments.

Keywords: data fusion
Patient monitoring
novelty detection
Advisor: Tarassenko, L
Glacier dynamics

A model is proposed for the study of general two-dimensional 'polythermal' glacial ice flows. It consists of equations of conservation of mass, momentum and energy together with a constitutive relation between stress and strain rate and a full set of boundary conditions. A novel aspect is the consideration of the moisture content of temperate ice as an enthalpy variable: this represents a first attempt at incorporating the glacial hydrology in a dynamical model.
One of the bedrock boundary conditions requires a knowledge of the so-called 'sliding law' relating the basal shear stress to the basal velocity (when the ice is temperate). A detailed model is proposed to determine this law, and upper and lower bounds for the basal velocity in terms of the stress are given by using a variational principle. The effect of cavitation on the sliding law is considered in the case of Newtonian flow, and it is shown to have a dramatic effect on the basal sliding.
We then turn to our analysis of the glacier flow model. Firstly we consider kinematic waves: an analogue of Nye's (1960) equation is derived and analysed from a nonlinear viewpoint. The formation and evolution of surface shocks is studied, and explicit results given for small perturbations to the surface profile. Secondly, we show how the modal may be used to predict a finite slope at the glacier snout by use of the method of strained coordinates.
Finally, steady state solutions are examined in the cases of large and small conduction. We demonstrate that there generally exists a large patch of basal ice which is almost temperate, but which slides at a velocity lower than that predicted by the sliding law: this is probably the most important result of the present work.

Advisor: Tayler, A
Corrosion protection by paint

This work investigated cathodic disbonding of an unpigmented phenalkamine-cured epoxy coating on mild steel, EC, exposed to 3.5 wt.% NaCl solution. Scanning Acoustic Microscopy (SAM), Scanning Kelvin Probe (SKP), Electrochemical Impedance Spectroscopy (EIS) and optical microscopy have been combined to conduct this study. Several factors affecting the cathodic disbonding process: Film thickness, Cation mobility, Electrolyte concentration, Temperature, Paint composition, Polarisation and Open circuit potential, have been investigated.
SAM results show that the disbonding of EC with a linear scribe spreads outwards from the defect with blisters forming at the anodes (as shown in SKP potential maps) within the disbond. The disbonded region does not correspond to complete adhesion loss as verified by peel-testing.
Semi-immersion tests show that disbonding under full- and semi-immersion conditions have similar behaviours and both follow parabolic kinetics indicating the disbonding is likely to be controlled by a transport process along the coating/metal interface.
An intact epoxy coated mild steel panel coupled with bare mild steel shows that the cathodic reaction beneath the coating obeys Tafel law.
A mathematical model simulating cathodic disbonding which produces realistic potential files and shows the oxygen reduction is mostly located near the disbond mouth has been developed.

Keywords: blister
cathodic disbonding
epoxy
SKP
SAM
Advisor: Sykes, J
Diaries real and fictional in twentieth-century French writing

Whereas the relationship between real autobiography and its fictional forms has been studied at length, the equivalent relationship for diaries has barely been acknowledged, let alone explored. This thesis follows the history of diary-writing – as a field that includes real and fictional diaries and the complex relations between them – in twentieth-century French writing. I take as my starting point the moment in the 1880s when, following a series of successful posthumous diary publications, a new generation of writers became aware that their own journaux intimes would probably come to be published, with considerable consequences for the way their literary œuvre and their very persona as an author (or their textual author-figure) would appear to readers. Of this generation, André Gide exerted by far the greatest influence over the course of diary-writing, and four works in particular experiment, in extremely diverse forms, with the literary possibilities of the diary: Les Cahiers d'André Walter (1891), Paludes (1895), Le Journal des faux-monnayeurs (1926), and his Journal 1889–1939 (1939). After the Second World War, diary-writing continued to draw on forms established by Gide, but now inflected by radical changes in attitudes towards the writing subject: Raymond Queneau's works published under the pseudonym of Sally Mara (1947–62) cast light on attitudes towards the diary at the time of a theoretical exclusion of the writing subject; Roland Barthes experimented with diaries at the point of a return of the writing subject (1977–79); and Annie Ernaux's published diaries between 1993 and 2011 demonstrate the role of diary-writing within the modern field of life-writing. Rather than making a gradual progress towards literary recognition, this history of diary-writing shows that, in a great variety of ways, diaries have consistently been used for their marginal or supplementary role, which simultaneously constructs and qualifies a literary œuvre and author-figure.

Keywords: Autobiography
French diaries - history and criticism
Diary novels
Life writing
Diaries
French literature
Advisor: Jefferson, A
Garfitt, T
Theories of learning in economics

How should we model learning behaviour in economic agents? This thesis addresses this question in two distinct ways. In the first set of chapters the assumption is that agents learn through the observation of others. They use Bayesian updating which together with specific informational assumptions can generate the problem known as herding with the potential for significant welfare losses. In the final set of chapters the agent is instead modelled as learning by example. Here the agent cannot learn by observing others, but has a pool of experience to fall back on. This allows us to examine how an economic agent will perform if he sees a particular economic situation (or game) for the first time, but has experience of playing related games. The tool used to capture the notion of learning through example is a neural network. Throughout the thesis the central theme is that economic agents will naturally use as much information as they can to help them make decisions. In many cases this should mean they take into consideration others' actions or their own experiences in similar but non-identical situations. Learning throughout the thesis will be rational or bounded-rational in the sense that either the best possible way to learn will be utilized (so players achieve full rational play, for example, through Bayesian updating), or a suitable local error-minimizing algorithm will be developed (for example, a rule of thumb which optimizes play in a subclass of games, but not in the overall set of possible games). Several themes permeate the whole thesis, including the scope for firms or planners to manipulate the information that is used by agents for their own ends, the role of rules of thumb, and the realism of current theories of learning in economics.

Advisor: Klemperer, P
Generation NGO: youth and development in urban India

This dissertation is about the role of NGOs in the lives of subaltern youth in urban India. It is an ethnography on the everyday lives of young people between the ages of 18-32 from impoverished 'red-light areas' in Kolkata who grew up participating in NGO youth programmes. This thesis investigates how NGOs partake in a process of subject making, and how young people interact with and improvise NGO subjectification to better their own lives in a world- class aspiring city.
The youth featuring in this dissertation spent their childhood and adolescence either residing in NGO shelter homes or regularly attending NGO drop-in-centres in their neighborhoods. They came of age attending NGO education programmes, job skills trainings, and human rights workshops. Grounded in 13 months of fieldwork, my ethnography tells the stories of young people’s lives after their participation in NGO programmes, amidst their everyday worlds of work, consumption, and politics.
My examination of the young people’s post-NGO daily lives in Kolkata makes three key contributions. First, it reveals the contradictions of NGO development. It examines the ambivalent effects of NGOs on subaltern young people’s gender and class identity, as well as their social and political subjectivity and mobility. Second, it illustrates the plural forms of agency practised by urban marginalised youth. My thesis demonstrates how young people are not just passive recipients of NGO development opportunities, but active negotiators of development as they interact with NGOs and navigate its attempts to regulate youth. Third, it illustrates how NGOs and post-NGO youth both foster and trouble class divisions in the world-class aspiring city of Kolkata. I illustrate how young people develop cultural dispositions that straddle across subaltern and middle classes and unsettle class boundaries but not inequalities.
This dissertation argues for ethnographic attention to the everyday lives of post-NGO youth as an analytical lens to theorise NGOisation and global city processes in contemporary India and the greater global South.

Keywords: development
South Asia
youth
NGO
cities
Advisor: Jeffrey, C
McDowell, L
Optical mapping signal synthesis

Although death due to lethal cardiac arrhythmias is the leading cause of mortality in Western Society, many of the fundamental mechanisms underlying their onset, maintenance and termination, still remain poorly understood. In recent years, experimental techniques such as optical mapping have provided useful high-resolution recordings of cardiac electrical dynamics during complex arrhythmias and defibrillation episodes, which have been combined with detailed computer simulations to further our understanding of these phenomena. However, mechanistic enquiry is severely restricted as the optical mapping technique suffers from a number of distortion effects which compromise the fidelity of the experimental measurements, presenting difficulties in the comparison of experimental data with computational simulations.
This Thesis presents a thorough investigation into the distortion effects encountered in optical mapping experiments, guided by the development of a coherent series of computational models. The models presented successfully characterise the specific mechanisms of fluorescent signal distortion due to photon scattering. Photon transport in cardiac tissue is modelled using both continuous (reaction-diffusion) and discrete stochastic (Monte Carlo) approaches to simulate the effects of photon scattering within the myocardium upon the recorded fluorescent signal, which include differing levels of detail and associated computational complexity. Specifically, these models are used to investigate the important role played by the complex ventricular structural anatomy, as well as the specifics of the experimental set-up itself. In addition, a tightly coupled electromechanical model of a contracting cardiac fibre is developed which provides an important first-step towards the development of a model to quantitatively assess the distortion observed when recording from a freely contracting cardiac preparation. Simulation of these distortion effects using the models allows discrimination to be made between those parts of the experimental signal which are due to underlying tissue electrophysiology and those due to artifact, facilitating a more accurate interpretation of experimentally-obtained data.
The models presented succeed in two main respects. Firstly, they provide a ‘post-processing’ tool which can be added on to computational simulations of electrical activation, allowing for a more accurate and faithful comparison between simulations and experiments, helping to validate predictions made by electrical models. Secondly, they provide a higher degree of mechanistic insight into the fundemental ways in which optical signals are distorted, showing how this distortion can be maximised or controlled. The understanding and quantification of the fundemental mechanisms of optical mapping signal distortion, provided by this Thesis, therefore fulfils an important role in the study of arrhythmia mechanisms.

Advisor: Gavaghan, DJ
Rodriguez, B
Determinants of nucleosome organisation and transcription regulation by histone marks

Epigenetics is the study of heritable changes in gene expression that do not involve changes in the underlying DNA sequence. Epigenetic pathways appeared in eukaryotes where multicellular organisms differentiate into different cell types, associated with different phenotypes. The differentiation process is achieved by modifications of the chromatin structure which, by altering the access of trans-factors to the DNA, result in gene activation and repression. Epigenetic mechanisms are therefore viewed as an "extra" layer of information that modulate the genetic information in time and space, necessary for the development and the response to environment stimuli. Although the recent development of high-throughput sequencing technologies has provided an unprecedented insight into epigenetic pathways, the mechanisms controlling the chromatin dynamic as well as their downstream effects on cellular processes are far from being fully understood.
In this thesis, our focus will be restricted to mechanisms acting on the nucleosome level. The first chapter will present the factors known to influence nucleosome positioning as well as the challenges related to the measurement of the nucleosome architecture. The second chapter will introduce a statistical approach, NucleoFinder, capable of identifying nucleosomes consistently positioned in a population of cells. In chapter three, we will make use of NucleoFinder to investigate the importance of cis and trans-factors on the nucleosome architecture in human and show that, despite variation across functional regions, cis-factors have a very modest in influence on nucleosome positioning. Finally, in chapter four, we will aim to identify clusters of histone modifications specific to functionally distinct regions, characterize their function and their association with gene expression level.

Keywords: epigenetics
gene regulation
nucleosome position
Advisor: Holmes, CC
Investigating the molecular mechanism of replication restart in fission yeast

Successful replication of the genome during each cell cycle requires that every replication fork merge with its opposing fork. However, lesions in the template DNA or protein-DNA barriers often impede replication forks and threaten the timely completion of genome duplication. If a fork encounters a replication fork barrier (RFB), it can be subject to a variety of fates. In some cases the replisome is maintained in a manner such that it can resume DNA synthesis when the barrier is removed. Alternatively the stalled fork is simply held in a competent state to merge with the opposing fork when it arrives. However, fork stalling can also precipitate dissociation of the replisome (fork collapse) or even fork breakage. If this happens the recombination machinery can intervene to restore DNA integrity and restart replication, albeit with a risk of causing deleterious genetic change if ectopic homologous sequences are recombined. I have exploited a site-specific RFB in fission yeast termed RTS1 to investigate the consequences of perturbing a single replication fork. RTS1 is a polar RFB (i.e. it blocks fork progression in a unidirectional fashion), enabling replication to be completed by the opposing fork. Despite this, fork blockage at RTS1 triggers a strong recombinational response that is able to restart DNA synthesis, which at least initially is highly error prone. Here, I present my work in establishing a live cell imaging approach to visualizing the recombinational response at the RTS1 RFB, demonstrating that the majority of cells initiate recombination-dependent replication (RDR). RDR begins within a few minutes of fork blockage and is only curtailed by the arrival of the opposing fork. It depends on the Rad52 protein, which remains associated with the restarted fork and whose presence correlates with its infidelity. I also illustrate the significance of various genetic factors, including Rad51, the Rad51 mediators, Fml1 helicase, Rad54 translocase, Pfh1 sweepase, and Cds1 checkpoint kinase, in modulating Rad52 localization and block-induced recombination at the RTS1 RFB.

Keywords: homologous recombination
DNA replication
RTS1
replication fork barrier
Advisor: Whitby, MC