VictorJuiz/thesis huggingface dataset:
Computational and experimental study of shock wave interactions with cells
Keywords: Cell mechanics, shock waves, high speed imaging, computational mechanics

This thesis presents a combined numerical and experimental study on the response of kidney cells to shock waves. The motivation was to develop a mechanistic model of cell deformation in order to improve the clinical use of shock waves, by either enhancing their therapeutic action against target cells or minimising their impact on healthy cells.
An ultra-high speed camera was used to visualise individual cells, embedded in tissue-mimicking gel, in order to measure their deformation when subject to a shock wave from a clinical shock wave source. Advanced image processing was employed to extract the contour of the cell from the images. The evolution of the observed cell contour revealed a relatively small deformation during the compressional phase and a much larger deformation during the tensile phases of a shock wave. The experimental observations were captured by a numerical model which describes the volumetric cell response with a bilinear Equation of State and the deviatoric cell response with a viscoelastic framework. Experiments using human kidney cancer cells (CAKI-2) and noncancerous kidney cells (HRE and HK-2) were compared to the model in order to determine their mechanical properties. The diﬀerences between cancerous and noncancerous cells were exploited to demonstrate a design process by which shock waves may be able to improve the speciﬁcity on targeted cancer cells while having minimal effect on normal cells.
The cell response to shock waves was studied in a more biophysically realistic environment to include inﬂuence of cell size, shape and orientation, and the presence of neighbouring cells. The most signiﬁcant diﬀerence was predicted when cells were in a cluster in which case the presence of neighbouring cells resulted in a four-fold increase on the von Mises stress and the membrane strain.
Finally the numerical model was extended to capture the effect of cell damage using one of two paradigms. In the ﬁrst paradigm the model captured microdamage during one shock wave but then assumed that the cell recovered by the time the next shock wave arrived. The second model allowed microdamage to accumulate with increasing number of shock waves. These models may be able to explain the strong effect that shock wave loading rate has on tissue damage.
In conclusion a validated numerical model has been developed which provides a mechanistic understanding of how cells respond to shock waves. The model has application in suggesting improved strategies for current uses of shock waves, e.g., lithotripsy, as well as opening up new indications such as cancer treatment.
When Partisan loyalty and performance evaluations conflict: a study of cross-pressured partisans in the US
Keywords: Partisanship
Elections
USA

A key expectation of elections is that voters hold elected officials to account for their performance in office. A contradiction exists in the literature between those who believe voters are incapable of exercising accountability and those who believe voters are successfully able to do so. This thesis addresses this contradiction and presents four empirical case studies in which I test the conditions under which voters exercise accountability. In order to explore these conditions I focus on situations in which partisan voters in the US receive a performance signal that directly contradicts their partisan loyalty. I refer to these voters as cross-pressured partisans. In the thesis I examine who these voters are and how they behave at election time. I find that partisans are responsive to signals about the quality of economic management of the incumbent government and that candidate competence matters at the local level. I find that the electoral response to corruption is more mixed. Although some partisans punish their party in light of a corruption scandal, corruption also depresses turnout and a lab experiment shows that voters do not punish candidates who embezzle funds if the candidate shares their group identity. The thesis finds that three factors moderate the extent to which partisan voters hold their own party to account: (1) individual voter characteristics; (2) the electoral context and; (3) the type of government performance. First, partisan voters with strong levels of affiliation to a party are less likely to exercise accountability whereas those with moderate levels are most likely to do so. Second, if the partisan stakes of an election are high, democratic accountability is low. Third, although partisan voters exercise accountability in the domain of economic management and candidate competence, the electoral response to corruption is more mixed. The thesis shows that there are many partisans who are conflicted between their loyalty to their party and their evaluations of incumbent performance. Under certain conditions this conflict incites behavioural change at election time. Partisans are therefore not incapable of holding their preferred candidate or party to account for their performance in office, but neither should they always be expected to do so.
Numerical methods for foreign exchange option pricing under hybrid stochastic and local volatility models
Keywords: option pricing
integrability
Euler scheme
calibration
conditional Monte Carlo
Monte Carlo
convergence

In this thesis, we study the FX option pricing problem and put forward a 4-factor hybrid stochastic-local volatility model. The model, which describes the dynamics of an exchange rate, its volatility and the domestic and foreign short rates, allows for a perfect calibration to European options and has a good hedging performance. Due to the high-dimensionality of the problem, we propose a Monte Carlo simulation scheme that combines the full truncation Euler scheme for the stochastic volatility component and the stochastic short rates with the log-Euler scheme for the exchange rate. We analyze exponential integrability properties of Euler discretizations for the square-root process driving the stochastic volatility and the short rates, properties which play a key role in establishing the finiteness of moments and the strong convergence of numerical approximations for a large class of stochastic differential equations in finance, including the ones studied in this thesis. Hence, we prove the strong convergence of the exchange rate approximations and the convergence of Monte Carlo estimators for a number of vanilla and exotic options. Then, we calibrate the model to market data and discuss its fitness for pricing FX options. Next, due to the relatively slow convergence of the Monte Carlo method in the number of simulations, we examine a variance reduction technique obtained by mixing Monte Carlo and finite difference methods via conditioning. We consider a purely stochastic version of the model and price vanilla and exotic options by simulating the paths of the volatility and the short rates, and then evaluating the "inner" Black-Scholes-type expectation by means of a partial differential equation. We prove the convergence of numerical approximations and carry out a theoretical variance reduction analysis. Finally, we illustrate the efficiency of the method through a detailed quantitative assessment.
Transition from the late Roman period to the early Anglo-Saxon period in the upper Thames Valley based on stable isotopes
Keywords: tooth enamel sequential sampling
bone collagen
human diet
livestock management
birth seasonality

Following the argument of cultural change between the Romano-British and Anglo-Saxon periods in Britain, the purpose of this thesis is to find evidence of change in human diet and animal husbandry in the Upper Thames Valley across this boundary. Research questions are set to find differences in human diet, animal diet, and birth seasonality of herbivores at Horcott, a site showing human activity in both periods. Stable carbon and nitrogen isotope measurements on collagen from humans and livestock animals and enamel carbonate extracted from herbivores were analysed. Results showed changes in the diets of cattle, sheep/goats, pigs, and human, and birth seasonality of cattle and sheep/goats. These changes were argued to have been caused by differences in the intensity of fertilising crop fields, the amount of animal protein fed to adult pigs, the amount of non-local food in human diet, and the significance and purpose of livestock rearing and the preference of dairy products. The outcome of this thesis enhances the understanding of: a) the strategy and the amount of human effort put into crop cultivation and livestock management; b) the availability and preference of food for humans depending on the period; and c) the site-dependent differences in the extent of change in the course of transition between the Romano-British and Anglo-Saxon periods. This thesis demonstrates the importance of animal data in order to discuss human diet, and the advantage of modelling enamel carbonate sequential data when analysing worn and shortened teeth.
Roles of weapons: significance, identity and value in Anyang late Shang (c. 1200-1050 b.C.) society China
Keywords: Weapons
Statistics
Metalwork wear analysis
Object biography
China

Weapons of the late Shang (c.1200-1050 B.C.), characterised by their frequent discovery and various forms and materials, have often been dogmatically deciphered as either symbolic signifiers or representing military equipment. Adopting an object biographical approach, the main objective of this thesis is to employ the corpus of weapons to explore the martial facet of Shang society. Multiple strands of evidence have been compiled for the investigation: two datasets composed of over 200 complete tombs with their assemblages from the Anyang site of the late Shang, finds from non-burial contexts, the British Museum bronze weaponry collection, and contemporaneous texts. Using for the first time both statistical tools and metalwork wear analysis, this thesis challenges our understanding of the weapons of the Shang from their classification in archaeological reports to their functions and roles in society. The diverse types and materials of weapons and their multifaceted functions also shed light on interactions between objects and human beings.
Healing sanctuaries: between science and religion
Keywords: Ancient Greece
ancient medicine
Aelius Aristides
iamata
healing deities
cure inscriptions
temple
sanctuary
healing
incubation
Asclepius

Divine healing has been often seen in opposition to human healing. The two spheres, have been considered as separate, both in space and in terms of elements involved. Asclepian sanctuaries have been mostly presented as domains of exclusively divine intervention, without any involvement of the human factor, possibly with the sole exception of dream interpretation.
However, the written testimonies of temple cures, both those in the form of cure inscriptions dedicated in sanctuaries and the literary accounts of the incubation experience, give us reasons to suppose that the practical side of the functioning of the asklepieia could have assumed the involvement of human medicine, with the extent of this involvement differing in various epochs. Regardless of physicians’ participation or its lack in the procedure, the methods applied in sanctuary healing appear to have evolved in parallel to the developments in medicine and their popular perception. Archaeological finds as well as the image of Asclepius as the god of medicine itself seem to confirm this.
Nevertheless, by no means should these connections between the two spheres be treated as transforming the space of religious meaning into hospitals functioning under the auspices of a powerful god. Although acknowledging them does entail inclusion of human medicine within the space dedicated to Asclepius, it does not thereby deny the procedure of incubation its religious and metaphysical dimension. On the contrary, it shows that to the Greek mind divine and human healing were not mutually exclusive, but overlapped and coincided with each other, proving that the Greek sense of rationality was quite different from the modern and could comprise far more than what we call today "scientific thinking".
Combustor simulators for scaled turbine experiments
Keywords: Aerospace

Gas turbine combustors employing a single lean combustion stage represent the next generation of design for reduced NOXemissions. These lean-burn combustors rely on swirl-stabilised flames resulting in highly non-uniform outflows. Non-uniform conditions adversely affect high-pressure turbine performance. 3D numerical simulations provide a means to understand and optimise engine design, however, the modelling of turbulence means experimental validation is crucial. Turbine test facilities operating at scaled, non-reacting conditions, with simulated combustor flows are an important source of validation data.
This thesis presents advances in combustor simulator design, testing and instrumentation relevant to the challenges of modern, highly-integrated turbine testing. The design of a lean-burn combustor simulator, characterised by swirl and non-uniform temperature, is presented. The design was based on measurements and predictions of engine conditions. Unsteady numerical simulations were employed as a predictive design tool.
An engine-scale combustor simulator was manufactured and characterised experimentally in a bespoke facility. Surveys of flow structure are presented, focusing on experimental turbine inlet data. These data confirmed that the combustor simulator reproduces the important features of a lean-burn combustor; e.g. swirling mainstream flow and high turbulence intensity. The lean-burn combustor simulator will be the first of its kind to be implemented in a rotating turbine test facility, and will provide important validation data.
Measurement techniques were developed alongside the core work. Miniaturised five-hole probe rakes for turbine inlet measurements were developed using additive manufacturing (AM). Building on this work, an open source AM five-hole probe design is presented with experimental validation. The problem of estimating pressure probe bandwidth was also addressed, and a simplified model is presented. These tools have direct applications in turbomachinery research.
Indirect interactions structuring ecological communities
Keywords: Indirect interactions
Interaction network
Food web
Tropics
Parasitoids
Brazil
Insects

Ecological communities are collections of species bound together by their influences on one another. Community structure, therefore, refers to the way in which these influences are organised. As a result, ecologists are mainly interested in the factors driving the structure, functioning, and persistence of communities. The traditional focus, however, has been on the feeding relationships among species (direct trophic interactions), whereas relationships mediated by a third species or the environment (indirect interactions) have been largely overlooked. I investigated the role of indirect interactions in structuring communities through a series of field experiments in a diverse assemblage of arthropods living on a Brazilian shrub species. I experimentally reduced the abundance of the commonest galler on the shrub and found that the perturbation resonated across the food web, affecting its structure and robustness. Since there was no potential for these effects to be propagated directly or indirectly via the documented trophic links, the effects must have spread non-trophically and/or through trophic links not included in the web. Thus, I investigated non-trophic propagation of effects in the system. I demonstrate that hatched galls of the commonest galler, which serve as habitat for other species, can mediate non-trophic interactions that feedback to the galler modifying its interactions with parasitoids and inquiline aphids. I performed further manipulative experiments, excluding ants, live galls and hatched galls, to reveal mechanisms for the non-trophic interaction modifications observed in this system. Finally, I explored how non-trophic interaction modification could affect the structure and stability of a discrete ecological community in the field. I investigated how the densities of certain pairs of groups relate to each other, and how their relationship changes in relation to a third group. Then, I assembled an "effect network" revealing, for the first time in an empirical community, a hidden web of non-trophic indirect interactions modifying the direct interactions and modifying each other. Overall, the thesis presents evidence that communities are strongly interconnected through non-trophic indirect interactions. This is one of the first empirical demonstrations of the context-dependent modification of interactions via non-trophic interactions. However, determining the mechanisms behind such interaction modifications may be unfeasible. Understanding how the observed effects relate to community structuring requires shifting our focus from bipartite interaction networks to a more holistic approach.
Natural enemies and the diversity of plant communities
Keywords: grassland
tropical forest
plant diversity
insect
pathogen
plant soil feedback
seed predator
rainforest
seedling
community ecology
density dependence
Panama
Wytham Woods

The processes that determine the structure of plant communities are of considerable practical and theoretical interest. Natural enemies such as herbivores, seed predators and pathogens provide one potentially important influence on plant diversity. I investigated the effects of natural enemies on plant diversity in two contrasting, species-rich plant communities (tropical forests in Panama and temperate grasslands in the UK), focusing on pre-dispersal seed predation by insects, and the mortality of seeds and seedlings caused by soil fungi. In Panama I found that pre-dispersal insect seed predators generate significant levels of mortality in multiple tropical tree species, with high heterogeneity in predation rates among individuals and at different forest sites. Insect seed predators were highly host-specific, consistent with a role in enhancing plant diversity. At Upper Seeds, a calcareous grassland site in the UK, I used manipulative experiments to show that soil fungi increase the diversity of plants propagating from soil seed banks. A parallel experiment in Panama, mimicking germination under light gap conditions, revealed differential effects of fungi among sites, with fungicide treatment appearing to increase the diversity of propagated seedlings at some sites but reducing it at others. These results suggest that the influence of soil fungi on pre-emergence mortality can alter plant diversity, even when post-emergence mortality from fungal pathogens is limited. In Panama, I also tested whether enemy-mediated mortality increases with rainfall, potentially contributing to the positive regional correlations widely observed between precipitation and plant diversity. In contrast to predictions, neither pre-dispersal insect seed predation nor the influence of soil fungi on seedling recruitment were affected significantly by site humidity, or (for soil fungi) with experimentally manipulated soil moisture levels. Overall, my results provide evidence that pre-dispersal seed predators and soil fungi can affect plant recruitment and diversity at early life stages, with potential consequences for the community structure of adult plants.
Aero-thermal performance and enhanced internal cooling of unshrouded turbine blade tips
Keywords: Gas turbines
turbine blade
High-speed
Aerodynamics
CFD
Experimental
Computational Fluid Dynamics
aero-thermal
tip leakage flow
engine realistic
cooling
blade tip
Heat transfer
compressible

The tips of unshrouded, high-pressure turbine blades are prone to significantly high heat loads. The gap between the tip and over-tip casing is the root cause of undesirable over-tip leakage flow that is directly responsible for high thermal material degradation and is a major source of aerodynamic loss within a turbine. Both must be minimised for the safe working and improved performance of future gas-turbines.
A joint experimental and numerical study is presented to understand and characterise the heat transfer and aerodynamics of unshrouded blade tips. The investigation is undertaken with the use of a squealer or cavity tip design, known for o↵ering the best overall compromise between the tip aerodynamics, heat transfer and mechanical stress. Since there is a lack of understanding of these tips at engine-realistic conditions, the present study comprises of a detailed analysis using a high-speed linear cascade and computational simulations. The aero-thermal performance is studied to provide a better insight into the behaviour of squealer tips, the e↵ects of casing movement and tip cooling. The linear cascade environment has proved beneficial for its o↵ering of spatially-resolved data maps and its ability to validate computational results. Due to the unknown tip gap height within an entire engine cycle, the e↵ects of gap height are assessed. The squealer's aero-thermal performance has been shown to be linked with the gap height, and qualitative different trends in heat transfer are established between low-speed and high-speed tip flow regimes.
To the author's knowledge, the present work is the first of its kind, providing comprehensive aero-thermal experimental research and a dataset for a squealer tip at engine-representative transonic conditions. It is also unique in terms of conducting direct and systematic validations of a major industrial computational fluid dynamics method for aero-thermal performance prediction of squealer tips at enginerepresentative transonic conditions.
Finally, after recognising the highest heat loads are found on the squealer rims, a novel shaped squealer tip has been investigated to help improve the thermal performance of the squealer with a goal to improve its durability. It has been discovered that a seven percent reduction in tip temperature can be achieved through incorporating a shaped squealer and maximising the internal cooling performance.
'Witness William Strode': manuscript contexts, circulation and reception
Keywords: Manuscripts
Verse Miscellanies
Early Modern Literature
William Strode
Textual Transmission

This thesis is concerned with how we read, edit, and understand the socio-textual relationships between seventeenth-century literary manuscripts. It takes as its subject William Strode (1601?-1645), poet, preacher, and Public Orator of the University of Oxford. In particular, this study examines the transmission and reception of Strode’s English verse, predominantly by examining verse miscellanies of the 1620s, 1630s and 1640s.
Chapter 1 provides the most extensive account of Strode's life to date, situating his career as a manuscript-publishing poet alongside his academic and clerical careers and social and literary contexts. Chapter 2 studies Strode's autograph manuscripts in detail, focusing on an autograph notebook, in which Strode transcribed and revised his poems; a booklet of eight poems which provide insight into how Strode circulated his verse; and a no longer extant, authorial manuscript of Strode's verse, which raises the question of whether or not Strode intended to print his poems in a single-author collection. Chapter 3 follows Strode’s poems from these autograph manuscripts into four verse miscellanies compiled by his most prolific collectors, and makes original arguments about how Strode’s poems circulated in seventeenth-century Oxford. This chapter ends with a discussion of two poems by Strode, once thought lost to scholarship. Chapter 4 moves from Christ Church to consider the social and textual coordinates of Strode's Oxford, and non-Oxford readers, offering reconsiderations and revisions of arguments about the provenance of a range of verse miscellanies. Chapter 5 considers the reception of Strode's poetry in the verse miscellany, and uses this evidence to refine theorizations of 'social editing' and 'textual malleability', before offering guidelines towards an edition of Strode’s English verse.