VictorJuiz/thesis huggingface dataset:
Multilevel collocation with radial basis functions

In this thesis, we analyse multilevel collocation methods involving compactly supported radial basis functions. We focus on linear second-order elliptic bound- ary value problems as well as Darcy's problem. While in the former case we use scalar-valued positive definite functions for constructing multilevel approximants, in the latter case we use matrix-valued functions that are automatically divergence-free. A similar result is presented for interpolating divergence-free vector fields. Even though it had been observed more than a decade ago that the stationary setting, i.e. when the support radii shrink as fast as the mesh norm, does not lead to convergence, it was up to now an open question how the support radii should depend on the mesh norm to ensure convergence. For each case above, we answer this question here thoroughly. Furthermore, we analyse and improve the stability of the linear systems. And lastly, we examine the case when the approximant does not lie in the same space as the solution to the PDE.

Keywords: Radial Basis Functions
Numerical Analysis
Multilevel
Collocation
Approximation Theory
Advisor: Wendland, H
Gillow, K
Application of a challenge model to assess the protective efficacy of oral typhoid vaccines in humans

Human infection by Salmonella Typhi has been occurring for the last 50,000 years and still accounts for &Tilde; 22million new cases each year worldwide. Through faeco-oral transmission, this human-restricted infection disproportionately affects the most impoverished sections of endemic communities where adequate sanitation infrastructure and effective vaccination approaches are lacking. Development of new control measures to accurately measure the burden of disease and to prevent infection with new vaccine candidates are hindered by an incomplete understanding of host-pathogen interactions and of what constitutes a protective human response after exposure.
In this thesis I describe the practical application of a recently developed human challenge model of typhoid infection in assessing new control measures, including the evaluation of the oral single-dose vaccine candidate, M01ZH09. In performing a large, double-blind, placebo-controlled study, I was able to measure the direct protective efficacy (PE) of vaccination with either M01ZH09 or 3-dose Ty21a by performing human challenge with 104CFU Salmonella Typhi, Quailes strain, 28-days later.
Using clinical and microbiological definitions to confirm typhoid diagnosis during a 14-day period after ingestion, I found insignificant levels of protection afforded by a single dose of M01ZH09 (12.9%), and a low PE after Ty21a vaccination (35%), demonstrating the stringency of the model and the endpoints used. Many additional insights into pathogen dynamics and host responses were found highlighting several important characteristics of oral vaccination. M01ZH09 was highly immunogenic, and both active vaccines significantly reduced bacterial burden (bacteraemia and stool shedding) while having no effect on symptomatic severity of infection in those diagnosed.
M01ZH09 receipt resulted in a significantly longer incubation period, suggesting underlying protective responses were being generated. Further findings included the first objective demonstration of primary bacteraemia occurring after typhoid exposure, and frequent asymptomatic infection or stool shedding in those exposed but remaining well. Overall, these data also demonstrated significant protective effects against challenge by anti-Vi antibody status and age at baseline. Taking these factors into account, M01ZH09 and Ty21a vaccination did convey an overall protective advantage against developing typhoid infection, each reducing the risk of diagnosis by ~two-fold during the challenge period.

Keywords: Human challenge studies
Elucidating the mechanism of mRNA translation during Drosophila oogenesis

mRNA localisation and translational control is a conserved, universal process involved in a number of essential cellular processes. Localised mRNAs are processed throughout their life cycle from transcription to degradation. How and where key mRNA remodelling steps occur is unclear. Furthermore, how mRNAs are translationally repressed during their transport, but translationally activated once localised, is a key question in the field. The Drosophila oocyte is a well used model system, and is patterned by the differential localisation of gurken, bicoid, oskar and nanos, which are all transcribed in the nuclei of the adjacent supporting nurse cell tissue. Here, I image localised mRNAs in live nurse cells and detect gurken with single molecule fluorescent in-situ hybridisation techniques for the first time. I use these assays to characterise the properties of gurken and oskar mRNAs in the nurse cells, and show they are strikingly different to the oocyte. I find that Processing bodies, which are key sites of translational regulation in the oocyte, contain significantly lower levels of the translational activator and Drosophila CPEB homolog, Orb. I show that, in contrast to oskar, whose translation is prevented during transport mainly by repressor proteins, gurken mRNA translation in the nurse cells is not prevented by a single repressor, but rather the absence of its translational activator, Orb/CPEB, in this tissue. Ectopic expression of Orb in the nurse cells is sufficient for the association of gurken with Processing bodies and premature gurken translation. These data highlight a new model for translational regulation through restricted spatial access to a translational activator, and I propose that such a mechanism could be widely deployed in other tissues.

Advisor: Davis, I
Fundamental models for the dynamics of electricity prices

In this work we propose a term structure power price model that, in contrast to widely accepted no-arbitrage based approaches, accounts for the non-storable nature of power. It belongs to a class of equilibrium game-theoretic models with players divided into producers and consumers. Consumers aim to maximize a mean-variance utility function subject to the inelastic demand of their own clients (households, businesses etc.) to whom they sell power. Similarly, producers, who own a portfolio of power plants each defined by a running fuel (gas, coal, oil etc.) and various physical characteristics (efficiency, capacity, ramp up/down times etc.), seek to maximize a mean-variance utility function consisting of power, fuel, and emission prices subject to production constraints. Our goal is to determine the term structure of the power price at which production matches consumption. In this work we show that in such a setting, the equilibrium price exists, and also discuss conditions under which it is unique.
We then extend the model to incorporate information about block contracts, transaction costs and liquidity. Moreover, we propose a tractable quadratic programming formulation for calculating the equilibrium term structure of electricity prices. Our numerical simulations examine the dependence of the term structure on various parameters of the model. Our model is applied to calculate the equilibrium term structure of electricity prices in the UK, by modeling the entire power grid consisting of a few hundred power plants.
We extend the model further by modeling startup costs of power plants. In contrast to other approaches presented in the literature, we incorporate them in a mathematically rigorous manner without relying on ad hoc heuristics. We propose a tractable approach for estimating startup costs of power plants based on their historical production. Through numerical simulations applied to the entire UK power grid, we demonstrate that the inclusion of startup costs is necessary for modeling electricity prices in realistic power systems.

Advisor: Hauser, R
Late-stage fluorination and perfluoroalkylation

In this thesis new synthetic routes towards perfluorinated compounds are described, as well as their radiolabelling with fluorine-18, with the aim of application in pharmaceutically interesting targets.
Part A investigates late-stage fluorination, i.e. retrosynthetic C–F bond disconnections. A silver catalysed electrophilic fluorodecarboxylation of fluorinated carboxylic acids for the formation of difluoromethyl-, trifluoromethyl-, and pentafluoroethylarenes is developed and transferred to a radiochemistry setting using [18F]Selectfluor bis(triflate).
Part B explores late-stage perfluoroalkylation via cross-coupling strategies. The use of visible light-mediated ruthenium catalysis is investigated for the radical trifluoromethylation and pentafluoroethylation of vinyl- and alkynylsilanes and alkynes. Finally, the first generally applicable copper-mediated cross-coupling of Ruppert-Prakash-like aryl(tetrafluoroethyl)trimethylsilanes (ArCF2CF2SiMe3) is presented.

Keywords: Trifluoromethylation
Fluorine
18F Radiochemistry
Fluorination
Photocatalysis
Perfluoroalkylation
Transition Metal Catalysis
Advisor: Gouverneur, V
Features and methods for improving large scale face recognition

This thesis investigates vector representations for face recognition, and uses these representations for a number of tasks in image and video datasets.
First, we look at different representations for faces in images and videos. The objective is to learn compact yet effective representations for describing faces. We first investigate the use of "Fisher Vector" descriptors for this task. We show that these descriptors are perfectly suited for face representation tasks. We also investigate various approaches to effectively reduce their dimension while improving their performance further. These "Fisher Vector" features are also amenable to extreme compression and work equally well when compressed by over 2000 times as compared to their non compressed counterparts. These features achieved the state-of-the-art results on challenging public benchmarks until the re-introduction of Convolution Neural Networks (CNNs) in the community. Second, we investigate the use of "Very Deep" architectures for face representation tasks. For training these networks, we collected one of the largest annotated public datasets of celebrity faces with minimum manual intervention. We bring out specific details of these network architectures and their training objective functions essential to their performance and achieve state-of-art result on challenging datasets.
Having developed these representation, we propose a method for labeling faces in the challenging environment of broadcast videos using their associated textual data, such as subtitles and transcripts. We show that our CNN representation is well suited for this task. We also propose a scheme to automatically differentiate the primary cast of a TV serial or movie from that of the background characters. We modify existing methods of collecting supervision from textual data and show that the careful alignment of video and textual data results in significant improvement in the amount of training data collected automatically, which has a direct positive impact on the performance of labeling mechanisms. We provide extensive evaluations on different benchmark datasets achieving, again, state-of-the-art results.
Further we show that both the shallow as well the deep methods have excellent capabilities in switching modalities from photos to paintings and vice-a-versa. We propose a system to retrieve paintings for similar looking people given a picture and investigate the use of facial attributes for this task. Finally, we show that an on-the-fly real time search system can be built to search through thousands of hours of video data starting from a text query. We propose product quantization schemes for making face representations memory efficient. We also present the demo system based on this design for the British Broadcasting Corporation (BBC) to search through their archive.
All of these contributions have been designed with a keen eye on their application in the real world. As a result, most of chapters have an associated code release and a working online demonstration.

Advisor: Vedaldi, A
Zisserman, A
Of poems and propositions: T.S. Eliot and the linguistic turn

This thesis describes how Eliot's concern for language and form finds roots in early twentieth century language philosophy. It also explores the way Eliot's early philosophical themes concerning language and meaning reemerge in his literary criticism and philosophical poetry during the 1920s and 1930s, and in his more explicitly philosophical Four Quartets. More significantly, this thesis historically elucidates Eliot's debt to the philosophies of Edmund Husserl and Bertrand Russell, reframing his philosophy within the two poles of the "Linguistic Turn". By closely examining Eliot's unpublished and only recently published essays and notes, the thesis unearths probable connections between Eliot's own philosophical interests and his later poetics, redefining his legacy as a prototypical modernist poet, and suggesting a new framework of study for scholars and students of literary modernism.

Keywords: Literature
Poetry
20th Century Literature
Phenomenology
Modernism
T.S. Eliot
Advisor: Bush, R
Johnson, J
On the measurement of optical scattering and studies of background rejection in the SNO+ detector

SNO&plus; is a liquid scintillator experiment designed to study a wide range of neutrino-related physics goals, such as solar neutrinos, reactor and geo-neutrinos, and neutrinoless double beta decay. The success of the experiment depends in part on the ability to accurately characterise the detector's optical properties, and also develop effective methods to suppress contributions from unwanted backgrounds.
This thesis presents one of the central calibration systems which will be used to make measurements of the detector's optical scattering properties. The hardware and its integration into the wider detector will be discussed. A simplifed analysis of simulated water data is also presented, in order to show that the scattering properties can be accurately measured. The reconstruction of photons' scattering position, length and angles can be achieved to a high degree of accuracy, with a small reconstruction bias and resolution in comparison to the scale of the detector itself.
This thesis also presents a study into the rejection of two important radioactive backgrounds that will be encountered during the scintillator phases of SNO&plus;: the (212Bi &plus; 212Po) and (214Bi &plus; 214Po) beta-alpha chains, where both components of each chain occur within a single detector trigger window, creating what is known as a BiPo pileup event. Two methods have been considered: one using a comparison between the cumulative time residual distributions of BiPo pileup and double-beta signal events, and the other using a log-likelihood difference method. Both methods perform extremely well, with the first being capable of rejecting &GT; 95% of BiPo pileup events for a 1% loss of signal, and the second rejecting &GT; 97% of backgrounds for the same signal loss.

Advisor: Biller, S
Active layer control for high efficiency perovskite solar cells

The work documented in this thesis concerns the control and modification of semiconducting perovskite thin films for their use in perovksite solar cells (PSCs). PSCs are a promising new thin-film technology, offering both high solar to electricity conversion efficiencies and cheap fabrication costs. Herein, the boundaries of perovskite solar cell research are pushed further by tackling several challenges important to the field.
Initially, this work focuses on understanding why the best PSCs made so far have been mesostructured devices, with the perovskite infiltrated into a scaffold. It is shown that this can be seen as simply a fabrication aid; without the scaffold, thin films easily dewet from the substrate. By understanding the crucial parameters important in carefully controlling this dewetting, it is minimised, and it is shown that scaffold-free planar heterojunction devices with high efficiencies can be fabricated.
This work leads on to the next section; the development of semi-transparent perovskite solar cells. In their present state, PSCs cannot compete with silicon as stand-alone modules. Here, the morphological control has been leveraged to realise a different embodiment – semi-transparent perovskite devices for use in building-integrated photovoltaics. Competitive efficiency and transparency are demonstrated. Moreover, a hybrid self-tinting power-generating window concept is fabricated, by combining the photovoltaic and electrochromic technologies.
In the third section of the thesis, the limitations of the most studied perovskite material, methylammonium lead halide, are addressed: its overly wide bandgap and thermal instability. To address these, the chemical constituents of the perovksite are altered, and the development of more efficient and more stable materials are reported. These are likely to be important for perovskite modules to pass international certification requirements for commercialisation.
Finally, an in-depth study on the effect of ambient moisture, relevant for considering scale-up and the fabrication environment needed, is carried out. It is shown that the presence of some moisture during film fabrication allows a reduction of defect states in the perovskite material, enhancing device performance and film quality.

Keywords: Perovskites
Advisor: Snaith, H
Security test and evaluation of cross domain systems

In practicable multi-level secure systems it is necessary occasionally to transfer information in violation of security policy. Machines for doing this reliably and securely are called cross domain solutions; systems incorporating them are cross domain systems. Data owners, especially in classified environments, tend to distrust other data owners, other systems and networks, their own users, and developers of cross domain solutions. Hence, data owners demand rigorous testing before they will allow their information into a cross domain system. The interests of data owners are represented by certifiers and accreditors, who test newly developed cross domain solutions and newly installed cross domain systems, respectively. Accreditors have the authority to grant approval to operate and the responsibility for accepting residual risk. Certification and accreditation have always been expensive and time consuming, but there are hidden inefficiencies and unexploited opportunities to predict the actions of accreditors and to control the cost of certification. Some case studies of successful and unsuccessful security certifications and accreditations were analysed using grounded theory methodology. It was discovered that inefficiency arises from conflation of the principle of defence in depth with the practice of independent verification and validation, resulting in an irresistible appearance of cost savings to managers with a possible explanation in the relative maturity of different levels of software engineering organisations with respect to policy, process, and procedures. It was discovered that there is a simple rule relating certifier findings to developer responses that predicts the duration of penetration testing and can be used to bound the schedule. An abstract model of cross domain system accreditation was developed that is sufficiently powerful to reason about collateral, compartmented, and international installations. It was discovered that the behaviour of accreditors satisfies the criteria for reliable signalling in the presence of asymmetric information due to Akerlof, Spence, and Stiglitz.

Keywords: cybersecurity
Advisor: Martin, A
Fléchais, I
Social policy and income inequality in the Southern Cone during the 20th century: a comparative perspective

This dissertation compares the effects of progressive social reform on income inequality in the Southern Cone of South America, Scandinavia, and Australasia. These regions faced comparable economic challenges at the start of the 20th century, but experienced different trends of income inequality after they introduced progressive policies in this period. Australasia and Scandinavia converged on a downward trend while the Southern Cone remained comparatively more unequal. The dissertation concentrates on three areas that significantly predict inequality in contemporary research: labour markets, education, and taxation and spending policies. Existing explanations usually focus on supply-side aspects of policy reform: wage regulation, and increased taxation and spending on education and social insurance, are thought to bring inequality down in the long-run. These reforms are seen as the outcome of the relative power of working class groups over elites. Despite institutional variation, the three regions enacted progressive policies to address distributional conflict and protect their economies from global risks. I study the demand-side of policy reform; policies faced considerable collective action problems to promote compliance and cooperation in order to work in the long-time and include populations at large. The fact that most people were motivated to comply meant that labour markets generated formality and standard wages, education increased human capital, and spending became stable as the tax base increased in Scandinavia and the Antipodes. The opposite happened in the Southern Cone as social actors tried to link selectively with the state while state officials neglected the material constraints that limited access to welfare and education. Each chapter spells out the conditions through which policy addressed collective action problems to motivate cooperation with wage agreements, sending children to school, and compliance with taxation and spending policies. Behind comparable aggregate numbers in these areas, the underlying social processes differed as Australasians and Scandinavians fostered cooperation between state and social actors, while the Southern Cone did not.

Advisor: Chan, T