VictorJuiz/thesis huggingface dataset:
Subgrain-size piezometry as a tool for measuring stress in polymineralic rocks
Keywords: piezometry
shear zone
rheology

We present a new subgrain-size piezometer calibrated using electron backscatter diffraction data from experimentally deformed quartz and olivine. Subgrain size is found to be inversely proportional to the applied stress. We tested a variety of different critical misorientations to define a subgrain boundary and concluded that a 1- or 2-degree threshold provides the optimum piezometric relationship.
The efficacy of subgrains to record the stress within individual phases in a polymineralic rock was tested using mixtures of olivine and orthopyroxene in a Deformation-DIA apparatus situated on a synchrotron X-ray beamline. For samples with grain sizes large enough to contain subgrains, piezometric measurements in olivine within the original calibration range displayed a good agreement with stresses measured through X-ray diffraction. Results indicated that a fine grain size severely limits the application of subgrain-size piezometry. For orthopyroxene, subgrains were too sparse to conclusively state whether the Goddard et al. (2020) piezometer can be applied to this mineral. Comparison of stresses measured through X-ray diffraction in each phase indicated that orthopyroxene supported a greater proportion of the load than olivine.
To explore stress partitioning further, we deformed olivine-orthopyroxene mixtures of various phase proportions in a gas-medium apparatus. The sample with intermediate composition was found to be weaker than would be expected simply from the grain-size sensitivity of traditional deformation mechanisms. Results from subgrain-size piezometry indicated that orthopyroxene is solely responsible for the weakening.
We apply the subgrain-size piezometer to quartz in polymineralic aggregates from the Great Slave Lake shear zone. To calculate the depth associated with each stress measurement, we conducted geothermometry. These stress measurements from subgrains are higher than those measured in other equivalent shear zones using grain-size piezometry, suggesting that the two microstructural features might record different portions of the deformation history
L2 listener attitudes towards speaker intelligibility, comprehensibility, and teaching quality
Keywords: Intelligibility
Comprehensibility
English as a foreign language
Native English speaking teachers
Accentedness
Non-native English speaking teachers
L2 attitudes
Reverse linguistic stereotyping
Listening

Intelligibility and the associated concepts of comprehensibility and accentedness are not objective features of speech, but are at least partially constructed by listener factors. Studies using a matched-guise technique, where listeners are led to believe that they are listening to two different speakers of different ethnicities, while they actually listen to the same native speaker, have found that listeners who believe a speaker to be non-Caucasian may judge them to sound less like a native speaker, to be a poorer quality teacher, and to be less intelligible. While the effects of native listener biases against non-native speakers and marginalised ethnicities have been well explored, fewer studies have focused on non-native listeners, especially in English as a foreign language (EFL) contexts. This study therefore aimed to determine whether the speech and teaching evaluations of English learners in Korea were affected by biases regarding the speaker’s ethnicity. 74 Korean L1 university students listened to a speech sample by the same native English speaker. Photographs displayed while listening implied to the listeners that the speaker was either Asian or Caucasian. Listeners rated the speaker on various measures, including personal attributes, comprehensibility, accentedness, and teaching quality, and completed tasks to measure comprehension and intelligibility. It was found that listeners who saw an Asian face were more likely to rate the speaker as having a less native-like accent, and found him less intelligible than listeners who saw a Caucasian face. However, no differences were found in listeners’ attitudes towards the speaker’s personal qualities or teaching ability. Listeners’ knowledge of L2s other than English and their exposure to English speakers were not found to mediate the effects of speaker ethnicity on ratings or listening performance.
High resolution secondary ion mass spectrometry analysis of boron in high strength steels and polycrystalline superalloys
Keywords: grain boundaries
NanoSIMS
steels
boron
superalloys
segregation
SIMS

Boron is added to high strength steels to increase hardenability and as grain strengthener in polycrystalline superalloys, but is difficult to study by many conventional techniques. The main aim of this study was to explore the application of high resolution secondary ion mass spectrometry (NanoSIMS) to analyse boron distributions in a range of high strength steels after different commercial heat treatments. New findings on the behaviour of boron at four stages of the manufacturing process (as-rolled, as-quenched, quenched and tempered and direct quenched) are demonstrated, and particularly information on how Ti plays an important role in maximising the beneficial effect of boron on hardenability. Boron was found to segregate at prior austenite grain boundaries during isothermal heat treatments by equilibrium segregation, and also during cooling by non-equilibrium segregation. In hot rolled samples, boron particles started to precipitate out during the hot rolling process, and during subsequent air cooling boron also segregated to prior austenite grain boundaries. Strong grain boundary segregation was observed in the as-quenched samples, with small precipitates near the grain boundaries as well as in the grain interiors. Finally, in quenched and tempered samples, small boron-containing precipitates were created during the tempering stage that were not visible in other samples. A longer heating time in the austenite region also gives higher boron segregation at grain boundaries. As a result, the direct quenching method can be an alternative process to reduce costs and increase overall efficiency in steel manufacturing as it shows a similar boron distribution to that developed by the conventional thermomechanical process. As well as these qualitative observations, quantitative analysis of boron segregation to a large number of grain boundaries has been demonstrated using the NanoSIMS, because it can map large areas in a short time. This is the only extensive quantification of grain boundary segregation performed with a NanoSIMS instrument to date with 100s of grain boundaries analysed. Quantification of boron-containing precipitate densities and size has also been reported. In another set of experiments on samples of a new polycrystalline Ni superalloy, the primary effect of boron addition has been shown to be the suppression of Cr-rich M23C6 carbides and the formation of Cr-rich M5B3 borides. NanoSIMS analysis of these superalloys was shown to provide complementary information to SEM, APT and TEM studies carried out by other researchers on the same alloys. The data presented in this thesis shows that NanoSIMS can be added to and can complement conventional techniques to guide the development of materials for industrial applications and understand the affect that heat treatments have on microstructure and materials properties.
Structural results for total search complexity classes with applications to game theory and optimisation
Keywords: computational complexity
TFNP

While the celebrated theory of NP-completeness has been very successful in explaining the intractability of many interesting problems, there still remain many natural and seemingly hard problems that are not known to be NP-hard. Several of these problems lie in the class of total NP search problems (TFNP), namely the class of NP search problems that always have a solution. Importantly, these problems cannot be NP-hard unless NP = co-NP. Notable examples of TFNP problems include FACTORING (given a natural number, compute its prime factorisation) and NASH (given a game, compute a mixed Nash equilibrium). In order to shed light on the complexity of these problems, researchers have attempted to classify them in various subclasses of TFNP such as PPAD, PPA, PPP, PLS, and CLS. A celebrated result in this line of research is the PPAD-completeness of NASH, yielding strong evidence that the problem is not polynomial-time solvable.
In this thesis we provide new structural results for TFNP subclasses and show how they can be used to classify natural problems arising from application areas such as game theory and optimisation. In the first part of this work, we construct more powerful tools for proving membership in PPAD, as well as PPAD-hardness. We directly apply these tools to show that the Hairy Ball theorem from topology ("you can't comb a hairy ball flat without creating a cowlick"), as well as the equilibrium computation problem in First Price Auctions with subjective priors, are both PPAD-complete.
In the second part of this thesis, we present our main result: the collapse CLS = PPAD ∩ PLS. We prove this surprising collapse by exhibiting the first non-artificial PPAD ∩ PLS-complete problem - a problem arising naturally from the famous gradient descent algorithm. Our result puts PPAD ∩ PLS on the map as a TFNP subclass that captures the complexity of natural problems.
In the third and final part, we provide various structural results for the classes PPA-k (corresponding to arguments modulo k), including the first topological characterisations of these classes. As a direct application, we prove that NECKLACE-SPLITTING with k thieves - a notorious problem in combinatorics and fair division - lies in PPA-k under Turing reductions.
Duties in tort law and its theory
Keywords: Duties
Tort Law

This thesis has three aims. The primary aim is to consider the widespread claim that torts are wrongs or (equivalently) breaches of duty. This claim is often presented as essential to understanding tort law’s true nature and, relatedly, to the refutation of ‘instrumentalism’. I argue against the claim and in favour of duty-scepticism. This requires me to disambiguate the claim, reject some of its meanings as trivial or tautologous, and argue that those that remain fail to identify a necessary or general feature of tort law. Importantly, however, I also reject the common association between duty-scepticism and instrumentalism. The insistence that torts are breaches of duty has therefore become a distraction in the debate against the instrumentalists, who would be better refuted in other ways. The second aim of my thesis is to do this, by explaining how the defendant’s liability may be justified (non-instrumentally) by his harm-causing conduct (whether or not that conduct is a breach of duty). Here I rely upon the well-known ‘continuity thesis’, which I defend from certain objections. One of its implications is that defendants’ duties of repair arise strictly (that is, regardless of fault) and that this is indeed the logically primary case. That then leads to my third and final aim, which is to explain why tort liability is conditional, in the vast majority of cases, upon defendant fault. I do this by identifying several benefits in having a fault standard, while arguing that these remain, in an important sense, secondary. My thesis as a whole therefore decentres fault and wrongdoing, two concepts often taken to be integral to anti-instrumentalism, while nevertheless showing, through the continuity thesis, that anti-instrumentalism is ultimately correct.
Futureproofing EU law: the case of algorithmic discrimination
Keywords: EU law
general principles
non-discrimination
algorithmic discrimination

The paper presents the European Charter of Fundamental Rights (the Charter) and the General Principles of European Union (EU) law as tools which can be used to futureproof the current EU non-discrimination framework against the main substantive challenges raised by algorithmic discrimination. The first chapter identifies the narrow personal and material scope of the current non-discrimination framework as being substantial limitations in the face of algorithmic discrimination, the effects of which are also discussed. The Charter and the General Principles are presented as potential solutions, given their goal to ensure the evolution of EU law in response to societal changes and technological development. The second chapter provides a closer look into these futureproofing tools and their dynamic, as well as the role of the Court in applying them and the potential issues involved with it doing so, including claims of judicial activism and competence creep. Having set out what needs futureproofing and why, as well as the tools available for the task, chapter three discusses ways in which the futureproofing process itself could unfold and argues that there are four approaches that the Court could take, each with its respective benefits and limitations. These four approaches are presented as being complementary rather than mutually exclusive, giving the Court the chance to use the most appropriate one in each specific case and therefore the possibility to futureproof EU non-discrimination law for the age of Artificial Intelligence.
An fMRI study on the effects of the dopamine & noradrenaline reuptake inhibitor bupropion on reward processing in depressed individuals
Keywords: major depressive disorder
anhedonia
neuroimaging
dopamine
psychopharmacology
reward processing

Anhedonia, the loss of pleasure or motivation for usually enjoyable activities and rewards, is an established cardinal symptom in Major Depressive Disorder (MDD) whose underlying pathophysiology is not well-understood, and which lacks specific efficacious treatments. This thesis investigates the effects that bupropion, a dual reuptake inhibitor of dopamine and noradrenaline, has on the neural substrates implicated in reward processing amongst clinically depressed individuals compared to unmedicated healthy controls. This investigation may help elucidate the role of aberrant dopaminergic activity on reward processing and the relevance of reward within anhedonia. First, examining baseline neural activation during completion of a monetary reward learning task revealed significantly different functional activity patterns at the whole brain level and for pre-specified anatomical regions of interest in MDD patients compared to healthy volunteers. These activation clusters largely pertained to brain regions implicated in the dopaminergic system, including the striatum, orbitofrontal cortex, and insular cortex. However, this was not found to correlate with symptomatic severity of anhedonia at baseline, which showed significant group differences in anhedonia and positive affect between depressed and healthy control participants.
Administering the NDRI-antidepressant drug bupropion was found to normalise initially aberrant neural activation during reward processing in MDD patients compared to their baseline measures and activation clusters obtained in healthy volunteers. Given the widely reported difficulty in the treatment of reward-related impairments with SSRIs, studying bupropion’s effects on neural activation during reward processing contributes to our understanding of alternative therapeutic options for alleviating maladaptive cognition associated with anhedonic MDD aside from those targeting the serotonin system. The gained insights may thus help inform the development and implementation of more precise and efficacious pharmacological interventions used for treating symptoms of anhedonia in clinical depression. Methodological strengths as well as possible limitations to the findings obtained in this study are discussed.
Harnessing oxonium ions for catalysis and arylation
Keywords: chirality
aryne
oxonium ion

This thesis describes work on the synthesis and applications of trialkyl and triaryloxonium ions. Chapter 1 describes the development of a transannular dehydration methodology to construct ‘stable’ trialkyloxonium ions from cyclic triols along with work towards using them to catalyse simple transformations.
In Chapter 2, the development of a mild, functional group tolerant method for the generation of arynes from fluoroarene or phenol derived triaryloxonium ions is described. Further work on triaryloxonium ion chemistry involving the construction of helically chiral triaryloxoniums with defined point chirality at oxygen and resolution of the enantiomers is described in Chapter 3.
Advancing remote sensing methods to monitor wildlife
Keywords: remote sensing
telemetry
movement ecology
convolutional neutral network
unmanned aerial vehicle
object detection
GPS
wildlife
audiometry
machine learning
elephant
bushmeat
poaching
aerial survey
Boma
anthrophony
corral
Kraal

Historically, natural history museums have collected and preserved specimens to provide data on the occurrence and distribution of wildlife populations. Zoologists still track animals by recording footprints, collecting dung and spoor and observing, recording and quantifying behaviour from the ground. However, these traditional observational techniques allow only a few populations to be monitored at once at limited spatial scales and disturbance from the ground can disrupt observation of natural behaviour. We are now in a golden age of technological advances and are able to remotely monitor and track wildlife via a variety of electronic sensors. Significant questions remain about how best to methodologically apply these new technologies for the purposes of wildlife monitoring. In this thesis, I consider challenges of using Earth observation satellites and unmanned aerial vehicles (UAVs) to track wildlife and understand movement in relation to the expanding human footprint and anthropogenic risk. Specifically: (i) I collate and analyse spatially explicit data on the distribution of illegal hunting incidences via a systematic map. I show that hunting increases in proximity to roads, water bodies, and human settlement areas and there is a considerable lack of systematically collected quantitative data. (ii) I investigate acoustic disturbance to understand anthrophony from the species perspective. I create a mitigation method applied in the case of UAV noise using species weighted audiograms (iii) I test whether very high-resolution satellite imagery and machine learning can be used to automate the detection of African elephants in vast heterogeneous landscapes. This is achieved presenting a new method to monitor elephants (iv) I record the spatial relationship of African elephants in relation to the human footprint using GPS tracking data and satellite imagery. I show elephants readily adapt their foraging habits and itineraries, spatially and temporally in relation to human settlement. Accurate and up-to-date data is vital for effective wildlife conservation planning. Remote sensing technologies offer enhanced capabilities to understand the spatial relationship between wildlife and the increasing human footprint. This body of work contributes to the global wildlife conservation effort by devising methods that can enable more reliable data collection at larger spatial scales.
Vapour detection of explosives, chemical agents and drugs
Keywords: percolation
chemiresistors
conductive materials
explosives detection

The detection of ultra-low concentrations of clandestine material has many applications across many sectors, particularly in relation to the military and security. The detection of many of these types of materials, and especially in the case of explosives, is made challenging because of low vapour pressures and intentional attempts at concealment. The aim of this project is to create a new type of sensing system for portable, in the field detection, where the active components are chemiresistive layers operating in the specifically targeted region between being insulating and fully conducting, known as the percolation region. Applying percolation theory to chemiresistive conducting layers increases sensitivity, and exploring new methods of analysis, deposition and deployment has the potential to increase selectivity.
When considering how sensors may be deployed in the field, the first challenge to overcome is to assess how current lab-based analytical techniques are, in some cases, inhibited by the parameters imposed on them as a function of being carried out in a highly controlled environment, and how that may not always translate into real-world utility. Next, sensors are created based on a percolation network of conductive polymers on a glass substrate, and the effect of incorporating gold nano-islands onto the substrate to support percolation network formation is assessed. In order to increase potential applications, percolation sensors are then created on flexible substrates and compared against both those on glass substrates and against other polymer sensors created in other research groups using different methods. One drawback of conducting polymers is that humidity often has an adverse effect on sensing performance. Metal organic frameworks have shown improved stability under humid conditions, and so finally conductive 2D MOFs are synthesized and deposited in novel ways on a variety of substrates and assessed as sensing materials.
Understanding transport behaviour and policies to increase walking and cycling
Keywords: socio-ecological framework
longitudinal study
active travel
PASTA

This thesis examined the factors affecting active mobility, walking and cycling, in urban environments using a multilevel perspective, from individual agency to built environment, to national-level policies. Understanding that health behaviour change is complex, and cannot be achieved through a single one-size-fits-all policy is the key premise of this thesis. In order to recognise the system-wide influences on walking and cycling, a socio-ecological framework was developed. This combines insights from psychological literature, transportation, and broader policy, and presents their relative roles and interactions in determining urban transport. Statistical analysis based on data from seven European cities showed the crucial role attitudes and psychosocial variables play in determining active travel. Based on the principles of realist evaluation, an analysis of interventions aimed at changing the psychosocial mindset of study participants in four of the seven cities revealed the short-term positive effects of such soft-measure interventions. However, the analysis also emphasised the need to change people's experiences for these measures to have a lasting effect. Finally, an economic analytical framework was developed to evaluate the potential effectiveness of a nation-wide policy (higher fuel taxes) to reduce car use and increase active travel. While including physical inactivity as a social cost greatly increases the optimal value of a fuel tax, limiting factors such as the psychosocial mindsets of people, or lack of suitable infrastructure, reduce the potential impact of such policies. Hence, working in an integrated, multidisciplinary manner is necessary for changing complex systems such as urban transport, physical activity-related health, and reducing carbon dioxide emissions.