VictorJuiz/thesis huggingface dataset:
Tidal turbine array modelling

Computational fluid dynamics (CFD) is used in this thesis to model wind and tidal stream turbines and to investigate tidal turbine fence performance. There are two primary objectives of this work. The first is to develop and validate an actuator line method for the simulation of wind and tidal turbines which applies the blade forces to the flow field without the need for a regularisation kernel. The second is to examine tidal fences using, in part, the newly developed actuator line method.
A potential flow equivalence method for determining the relative velocity to the blade chord and flow angle at the rotor blades in the actuator line method is proposed and validated. Results for simulations using this method compare favourably with those from both experiments and alternative computational methods, although the present model’s results deviate from experimental results in the vicinity of the blade tips.
A CFD-embedded blade element-momentum tool is used to design rotors for operation in infinitely wide tidal fences spanning a tidal channel. Rotors are designed for fences with several different blockage ratios, with those designed for high blockage flows having greater solidity than those designed for operation in fences with lower blockage. It is found that designing rotors for operational blockage conditions can significantly improve the power output achieved by a tidal fence. Improved power output for higher blockage conditions is achieved by the application of greater thrust to the flow.
Actuator line simulations of short (up to 8 turbines) fences with varying intra-rotor spacing and number of rotors confirm that hydrodynamic performance of the rotors improves as the spacing is reduced and as rotors are added to a fence. The position of a rotor within the fence impacts its performance; rotors at the ends of a fence extract reduced power compared to those at the centre of the fence, particularly for tip speed ratios greater than the design tip speed ratio.

Keywords: wind energy
rotor design
Tidal energy
CFD
renewable energy
Advisor: Willden, R
Identification of the cellular and molecular mechanisms of IL-23 driven intestinal inflammation

IL-23 is an essential mediator of chronic intestinal inflammation in experimental models of colitis. Polymorphisms in the IL23R locus are associated with IBD susceptibility in humans. The biological activity of IL-23 has been linked to Th17 cells but little is known about the cellular and molecular mechanism by which IL-23 drives intestinal inflammation. The work presented herein has identified that direct IL-23 signalling into CD4+ T cells was not only required for the accumulation of Th17 cells in the intestine but also modulated their phenotype. Through direct cell intrinsic effects on T cells, IL-23 drove the emergence of an IL-17A+IFN-γ+ population of T cells that co-expressed RORγ and T-bet. Interestingly, we found that expression of RORγ but not T-bet by T cells was required for the development of intestinal inflammation. Furthermore, colitis induced by T-bet deficient T cells was dependent on IL-17A, and showed a unique inflammatory phenotype, thus demonstrating that pathogenic intestinal Th17 responses can develop independently of T-bet. In addition, using transcriptional profiling we identified a core set of genes that is regulated by direct cell-intrinsic IL-23 signals into intestinal CD4+ T cells. This revealed a previously unrecognised role for IL-23 in suppressing Th2 associated genes, such as GATA3 and IL-33R. Functional experiments demonstrated that expression of GATA3 in CD4+ T cells limited their colitogenic potential, suggesting that IL-23-mediated inhibition of GATA3 might contribute to the development of intestinal inflammation. Finally, we described a novel function for IL-33 as a factor that promotes Foxp3+ iTreg differentiation in vitro and in vivo through direct effects on T cells. This activity of IL-33 was inhibited in the presence of IL-23, providing a mechanistic link for the known role of IL-23 in restraining iTreg generation. Collectively, these data suggest that IL-23 promotes acquisition of a pathogenic effector T cell phenotype through multiple mechanisms. This indicates that therapeutic blockade of IL-23 is likely to reduce pro-inflammatory mediators while also facilitating the expansion of regulatory pathways that might help to re-establish intestinal homeostasis.

Keywords: inflammatory bowel disease
effector CD4 T cells
mucosal immunology
IL-23
regulatory T cells
Advisor: Powrie, F
Who cares for orphans? Challenges to kinship and morality in a Luo village in Western Kenya

This dissertation analyses an ethnographic study of how people in a peri-urban, agricultural village in western Kenya have responded to the questions of who will care for children, and how, when those children’s parents, or other primary caregivers, have died. It examines the practical and ideological implications of wide-scale orphaning among a population that has experienced increased numbers and proportions of orphaned children mainly due to HIV/AIDS, as well as the gradual depletion of resources in terms of both the availability of middle-aged adults and the security of economic livelihoods. The research explores how specific caring relationships, as well as general sociality, have been challenged, adapted, and affirmed or rejected normatively and practically in this context.
The research revealed a high degree of questioning in people’s efforts to forge responses to children’s orphaned situations. Rarely was there unambiguous consensus in the study context concerning what should be done in response to children’s orphanhood in light of families’ diminished livelihood capacities. More broadly, there was a distinctive concern with how such situations might be appraised in moral terms. The analysis therefore focuses on three main concerns, including: how to understand uncertainty as a condition of life, and the implications of this; how a shared perspective of uncertainty has spurred a concern with morality in the study context, and specifically galvanised a moral economy of kinship; and how the concern with morality affected what was deemed at stake in people’s lives.

Keywords: orphans
kinship
morality
care
Luo
HIV/AIDS
Kenya
Advisor: Pratten, D
Boyden, J
Humiliation and liberal democratic politics

The concept of humiliation has not received much attention from political theorists, despite the fact that themes related to dignity, respect, and honour have become more prominent in recent years. Contributions to the literature in political theory and related disciplines that do focus on humiliation tend to cast humiliation in one particular mould: as a violation of human dignity or equality, or as the emotional response to such a violation. Writers who take this view of humiliation often conclude that liberal democratic states and other actors committed to liberal democratic principles should not engage in humiliation.
In this thesis, I provide an in-depth examination of the concept of humiliation, clarifying certain features of humiliation that are presented ambiguously in the current literature. I emphasise the complexity of humiliation and the variety of forms it can take, beyond the violation of human dignity or equality. Humiliation can, for instance, consist of damage to the images of relatively powerful individuals or groups. I then argue that normative conclusions about the responsibilities of actors committed to liberal democratic principles vis-à-vis humiliation ought to be more nuanced than the conclusions found in much of the current literature. In some circumstances, these actors may legitimately engage in action that constitutes and/or leads to humiliation in order to uphold liberal democratic principles. But I also endorse certain concerns regarding this kind of action. Decisions about the proper approach to humiliation on the part of actors committed to liberal democratic principles should be made, I argue, with sensitivity to the particular political context.

Keywords: humiliation
politics
Advisor: Philp, M
Control of the mitotic spindle by dynein light chain 1 complexes

Robust control mechanisms ensure faithful inheritance of an intact genome through the processes of mitosis and cytokinesis. Different populations of the cytoplasmic dynein motor deﬁned by speciﬁc dynein adaptor complexes are required for the formation of a stable bipolar mitotic spindle. This study analysed how different dynein subcomplexes contribute to spindle formation and orientation. Various dynein subpopulations were identiﬁed by mass spectrometry. I have shown that the dynein light chain 1 (DYNLL1) directly interacts with the kinetochore localised Astrin-Kinastrin complex as well as the spindle microtubule associated complex formed by CHICA and HMMR. I have characterised both complexes and identiﬁed unique functions in chromosome alignment and mitotic spindle orientation, respectively.
I have found that Kinastrin (C15orf23) is the major Astrin-interacting protein in mitotic cells and is required for Astrin targeting to microtubule plus ends proximal to the plus tip tracking protein EB1. Fixed cell microscopy revealed that cells over-expressing or depleted of Kinastrin mislocalise Astrin. Additionally, depletion of the Astrin-Kinastrin complex delays chromosome alignment and causes the loss of normal spindle architecture and sister chromatid cohesion before anaphase onset (Dunsch et al., 2011).
Using immunoprecipitation and microtubule binding assays, I have shown that CHICA and HMMR interact with one another, and target to the spindle by a microtubule-binding site in the amino-terminal region of HMMR. CHICA interacts with DYNLL1 by a series of conserved TQT motifs in the carboxy-terminal region. Depletion of DYNLL1, CHICA or HMMR causes a slight increase in mitotic index but has little effect on spindle formation or checkpoint function. Fixed and live cell microscopy reveal, however, that the asymmetric distribution of cor tical dynein is lost and the spindle in these cells fails to orient correctly in relation to the culture surface (Dunsch et al., 2012).
These ﬁndings presented here suggest that the Astrin-Kinastrin complex is required for normal spindle architecture and chromosome alignment, and that per turbations of this pathway result in delayed mitosis and non-physiological separase activation, whereas HMMR and CHICA act as part of a dynein-DYNLL1 complex with a speciﬁc function deﬁning or controlling spindle orientation.

Keywords: Spindle orientation
Mitotic spindle
Advisor: Barr, F
Radiative corrections to e+e- to mu+mu- in the Glashow-Salam-Weinberg model

A complete renormalization scheme for the Glashow-Salam-Weinberg model is presented. As input parameters the scheme uses the fine structure constant, α, the muon decay constant, Gμ and the Z° mass, MZ which are known or will be measured to high accuracy in the near future. These are used along with the Higgs and fermion masses to obtain the W mass, MW. The full one-loop weak radiative corrections to the longitudinal polarization asymmetry, Apol, and the forward-backward asymmetry, Afb, in e+e- → μ+μ- are then calculated both on and off resonance. On resonance the results depend extremely sensitively on the Z mass, MZ, and to a lesser extent on the top quark mass, mt, and the Higgs mass, MH, showing that this is a good place to test the standard model at the one loop level. The results are displayed over the full range of the parameters allowed by experimental and theoretical constraints. It is suggested that sufficiently accurate experiments may be able to set an upper bound on one of mt or MH if the other is known. It is noted that on resonance Apol is only weakly dependent on the beam pipe and on the nature of the outgoing fermions. Comparison is made with other calculations of Afb and the agreement is found to be good. The predictions are also compared with measurements of Afb off resonance and are found in all cases to lie within the experimental errors. Previous analyses that indicated a possible discrepancy are shown to be incorrect.

Advisor: Lynn, B
Sandars, P
Spoken letter recognition with neural networks

Neural networks have recently been applied to real-world speech recognition problems with a great deal of success. This thesis developes a strategy for optimising a neural network known as the Radial Basis Function classifier (RBF), on a large spoken letter recognition problem designed by British Telecom Research Laboratories. The strategy developed can be viewed as a compromise between a fully adaptive approach involving prohibitively large amounts of computation, and a heuristic approach resulting in poor generalisation. A value for the optimal number of kernel functions is suggested, and methods for determining the positions of the centres and the values of the width parameters are provided. During the evolution of the optimisation strategy it was demonstrated that spatial organisation of the centres does not adversely affect the ability of the classifier to generalise.
An RBF employing the optimisation strategy achieved a lower error rate than a multilayer perceptron and two traditional static pattern classifiers on the same problem. The error rate of the RBF was very close to the theoretical minimum error rate obtainable with an optimal Bayes classifier. In addition to error rate, the performance of the classifiers was assessed in terms of the computational requirements of training and classification, illustrating the significant trade-off between computational investment in training and level of generalisation achieved.
The error rate of the RBF was compared with that of a well established method of dynamic classification to examine whether non-linear time normalisation of word patterns was advantageous to generalisation. It was demonstrated that the dynamic classifier was better suited to small-scale speech recognition problems, and the RBF to speaker-independent speech recognition problems. The dynamic classifier was then combined with a neural network algorithm, greatly reducing its computational requirement without significantly increasing its error rate. This system was then extended into a novel system for visual feedback therapy in which speech is visualised as a moving trajectory on a computer screen.

Advisor: Tarassenko, L
Ultrafast carrier dynamics in organic-inorganic semiconductor nanostructures

This thesis is concerned with the influence of nanoscale boundaries and interfaces upon the electronic processes that occur within the inorganic semiconductors. Inorganic semiconductor nanowires and their blends with semiconducting polymers have been investigated using state-of-the-art ultrafast optical techniques to provide information on the sub-picosecond to nanosecond photoexcitation dynamics in these systems.
Chapters 1 and 2 introduce the theory and background behind the work and present a literature review of previous work utilising nanowires in hybrid organic photovoltaic devices, revealing the performances to date. The experimental methods used during the thesis are detailed in Chapter 3.
Chapter 4 describes the crucial roles of surface passivation on the ultrafast dynamics of exciton formation in gallium arsenide (GaAs) nanowires. By passivating the surface states of nanowires, exciton formation via the bimolecular conversion of electron-hole plasma can observed over few hundred picoseconds, in-contrast to the fast carrier trapping in 10 ps observed in the uncoated nanowires. Chapter 5 presents a novel method to passivate the surface-states of GaAs nanowires using semiconducting polymer. The carrier lifetime in the nanowires can be strongly enhanced when the ionization potential of the overcoated semiconducting polymer is smaller than the work function of the nanowires and the surface native oxide layers of nanowires are removed. Finally, Chapter 6 shows that the carrier cooling in the type-II wurtzite-zincblend InP nanowires is reduced by order-of magnitude during the spatial charge-transfer across the type-II heterojunction.
The works decribed in this thesis reveals the crucial role of surface-states and bulk defects on the carrier dynamics of semiconductor nanowires. In-addition, a novel approach to passivate the surface defect states of nanowires using semiconducting polymers was developed.

Keywords: photoluminescence
hot-carrier
trapping
semiconductor nanowires
exciton
doping
carrier dynamics
Mott transition
lifetime
charge transfer
ultrafast spectroscopy
carrier cooling
type-II heterojunctions
Advisor: Herz, L
Constructing South East Europe

In the post-Cold War era, the Balkans came to exemplify the power of resurgent nationalisms freed from the straitjacket of bipolar stability. The break-up of the Yugoslav federation suggested that exclusivist ethno-national identities trumped the logic of political and economic integration. Yet, by the early 2000s, regional cooperation made significant inroads into South East Europe. This study addresses the puzzle of why the Balkan states have engaged in a number of multilateral schemes in fields such as military security, trade, infrastructure development, energy, despite the region's divisive historical legacies and political instability.
The thesis explores the impact of three factors: regional interdependence denoting the socio-economic and political linkages which contribute to the convergence of Balkan states' material interests, external push referring to the policies for fostering regional cooperation adopted by key actors such as the EU, US, and NATO, and identity politics: the discourses on the borders, cultural make-up and history of a Balkan regional entity as well as the latter's relationship with constructs like Europe and the West. The thesis argues that external projection of power, rather than regional interdependence, accounted for the development and growth of Balkan regionalism. However, the push from outside was legitimised by Balkan collective identity built upon myths of belonging to and exclusion from 'civilised Europe'. Regionalism was not solely a reflection of the supply and demand for integrative frameworks, but amounted to a symbolic strategy for transforming the volatile Balkans into South East Europe by the adoption of the institutional norms and practices of international clubs such as the EU and NATO.
The case of regional cooperation in South East Europe contributes to the debates about the politics of interest and the politics of identity in the field of International Relations, and raises questions about the nature of power in contemporary Europe and the international society.

Advisor: Nicolaïdis, K
The macroeconomics of developing countries

The CFA consists several African economies adhering to one of two common currencies, and one of two central banks. The rules of the monetary union provide for the pooling of foreign assets, and the regulation of monetary expansion in each country. The French treasury guarantees the convertibility of CFA Francs into French Francs at a fixed rate. The thesis examines the impact of CFA membership on the macroeconomic performance of member states, assessing the claim that CFA institutions have influenced capital and labour markets, and have modified short run adjustment to external shocks.
There are a number of reasons why CFA membership could facilitate higher investment, (i) The rules governing money creation may lead to greater monetary prudence, and so lower inflation and price variability, and less uncertainty for investors, (ii) Guaranteed convertibility means that firms will never be prevented from importing capital goods by a lack of foreign exchange, (iii) Convertibility may encourage a greater degree of integration between French and CFA capital markets, so that domestic investment is not entirely dependant on domestic saving. A model of investment is constructed to incorporate these effects, and tested using time series and cross-sectional data. Support is found for (i) and (ii), but not for (iii).
If African labour markets are characterised by nominal wage inertia, the enforced low inflation may lead to excessive real wages, and CFA membership may impair efficient allocation of labour. However, evidence suggests this characterisation is usually inappropriate.
The pegged exchange rate may lead to persistent external imbalances: devaluation is not an option in response to a negative trade shock. This will not be a problem as long as an effective substitute for devaluation is found. A CGE model is constructed to examine the viability of various devaluation substitutes, none of which are found to be adequate.
An experimental and observational study of interspecific territoriality between the blackcap Sylvia atricapilla (Linnaeus) and the garden warbler Sylvia borin (Boddaert)

Ecological divergence between Blackcaps and Garden Warblers appears to be incomplete. They resemble each other closely in morphology and their foraging behaviour and food (in the breeding season) are at least broadly similar. Nevertheless, they are sympatric and occur together in a wide range of habitats although Garden Warblers are proportionately commoner in lower, denser vegetation.
The two species are strongly interspecifically territorial where they occur together. However, Blackcaps are more interspecifically aggressive than Garden Warblers and are clearly dominant to them in interactions. Blackcaps respond just as strongly to playback of Garden Warbler song as they do to that of Blackcap song. They sometimes intrude into Garden Warbler territories and seek- out and chase the territory holders. In contrast, with rare exceptions, any Garden Warblers which intrude into Blackcap territories are attacked and chased until they leave the area. Also, during song playback experiments, Garden Warblers approach the loudspeaker less closely in response to Blackcap song than they do to Garden Warbler song.
Many Blackcaps arrive on the breeding grounds before the earliest Garden Warblers do. A removal experiment, in which such established Blackcaps were systematically removed, showed that some of them had been keeping-out potential Garden Warbler settlers, since the latter then readily established territories and bred in a large part of the Blackcap-free zone. Normally, Garden Warblers have their territories outside Blackcat>-occupied habitat, partly because they are prevented by the aggressiveness of the Blackcaps from settling elsewhere. However, observation and song playback experiments have shown that, once established, Garden Warblers do defend their territories against both conspecifics and Blackcaps.
Blackcaps have recently increased dramatically in Britain and Garden Warblers have decreased simultaneously. However, although Blackcaps can limit the local breeding densities of Garden Warblers in any one year, it is not yet clear whether Blackcap numbers are a significant factor in determining the total sizes of Garden Warbler populations.

Advisor: Davies, N
Protein folding

Recent studies of the relationship between protein sequence and protein structure are reviewed. A detailed discussion of past attempts to predict the structure of a protein from its amino acid sequence, the protein folding problem, is presented and the strengths and weaknesses of these methods are examined. The root-mean-square deviation is studied and a benchmark for structural comparisons is established. A combinatorial approach to the protein folding problem is outlined and its advantages over existing methods is discussed. Specific algorithms based on the combinatorial approach are developed and applied to a variety of proteins. The success of this approach in terms of the root-mean-square deviation benchmark as well as the drawbacks of this method are presented.

Advisor: Phillips, D
Richards, F