VictorJuiz/thesis huggingface dataset:
Two-scale method for wall-bounded flows
Keywords: turbulence
computational method

Recent findings on wall-bounded turbulence prompt a new impetus for modelling development to capture and resolve the Reynolds-number-dependent influence of outer flow on near-wall turbulence in terms of the ‘foot-printing’ of the large-scale coherent structures and the scale-interaction associated ‘modulation’. A two-scale method is developed to couple a locally embedded near-wall fine-mesh DNS block with a global coarser mesh domain. The influence of the large-scale structures on the local fine-mesh block is captured by a scale-dependent coarse-fine domain interface treatment. The global near-wall coarse-mesh region outside the local fine-mesh block is governed by the augmented flow governing equations with forcing source terms generated by upscaling the space-time averaged fine-mesh solution. The validity and effectiveness of the method are examined for canonical incompressible channel flows at several Reynolds numbers. It is shown that the mesh-count scaling with Reynolds number is potentially reduced from O(Re^2) for the conventional fully wall-resolved LES to O(Re) for the present locally embedded two-scale LES. The method is also extended to the implementation in boundary layer flows. A 2-dimensional roughness element is used to trip a turbulent boundary layer. It is observed that large-scale disturbances originating from the trip have a much shorter lifetime and weaker foot-printing signatures on near-wall flow compared to those long streaky coherent structures in well-developed wall-bounded turbulent flows. For the tripped turbulent boundary layer, a Chebyshev block spectral mapping is adopted to propagate source terms, driving the upscaled equations to a target solution. The overall mesh count - Re scaling is estimated to reduce from O(Re^1.8) for the full wall-resolved LES to O(Re^0.9) for the present two-scale solution.
Egypt and the Hellenic economy: culture as a non-tariff trade barrier in the Atheno-Egyptian grain trade, 665-204BC
Keywords: Athens
Egypt
Saite
Classical Athens
ancient economy
grain trade
ancient

Without sufficient food for her population, and in the absence of the empire which had sustained her before the Peloponnesian War, fourth-century BC Athens relied on regular supplies of foreign grain. While the trade in grain has been subjected to sustained scholarly interest, few academics have considered why Athens chose one grain source above another. Most agree that at least a third of Athens’ grain requirements were satisfied from the Euxine, which was vulnerable to infrequent crop failure and sits at the end of a precarious and navigationally challenging shipping route exposed to danger from the Spartans, Byzantians and pirates. Conversely, there is insufficient evidence that Egypt, a voluminous grain source closer (by ancient sailing practices) than the Black Sea, contributed much to Athens’ food supplies before the Battle of Chaironeia (338BC). This thesis contributes one solution to this conundrum: that cultural differences constituted such a significant transaction cost to Atheno-Egyptian trade that it outweighed the dangers of the Euxine route. Applying approaches derived from New Institutional Economics to the Atheno-Egyptian case-study, this thesis pre-empts the Finleyan shibboleth that ancient trade cannot be considered economically rational by demonstrating the real economic costs of linguistic, religious, ethnic, philosophical, governmental, diplomatic and legal differences. Through charting a gradual convergence in these areas between the seventh and third centuries BC, a new perspective is offered on Egypt’s transition into a Hellenic economy which undermines the long established ‘Classical’-‘Hellenistic’ and ‘Western’-‘Oriental’ dichotomies which still pervade literature on the ancient economy.
Reliable attribution and projection of extreme heat events altered by human influence on the climate
Keywords: extreme value theory
numerical weather predictoin
extreme weather
climate modelling
extreme event attribution
climate change

Anthropogenic greenhouse gas emissions are now well-understood to be causing damaging changes to the climate. One of the many ways in which the climate is changing is through extreme weather events. Given the severe consequences of such events, understanding how human influence on the climate is affecting them is vital. This is the aim of the young field of 'extreme event attribution'. There now exist many established methods for attributing individual weather events to climate change, from probabilistic approaches utilising large climate model ensembles to deterministic storyline approaches. However, questions still remain over the reliability of these approaches, especially when considering the most unprecedented events. In this thesis, I show how weather forecast models could provide us with such reliable information about human influence on extreme weather --- focusing on extreme heat. These models are state-of-the-art and can be shown to be unequivocally able to simulate the detailed physics of specific extreme weather through successful prediction. I develop a perturbed initial- and boundary-condition approach within an operational forecasting system that aims to produce forecasts of individual events as if they had occurred in a world without human influence on the climate. These 'counterfactual' forecasts can be used to assess how not only the intensity, but also the probability of such events has changed. Although extreme weather attribution typically focuses on the past, the same approach could be used to produce forecasts in warmer future worlds --- thus providing vital information about how the most damaging weather may be expected to change in the future. I explore this theme of extreme weather projection, examining a novel approach to producing large climate model ensembles that span the range of uncertainty in future extreme weather. This work complements the specific nature of extreme event attribution, and they could together provide crucial information about climate risk.
Revenue patterns of piped water services in rural Africa
Keywords: archetype analysis
rural water supply
seasonality
sustainable development goals
Africa
financial sustainability

Rural Africa lags behind all other global regions in progress towards establishing universal and equitable access to safely managed drinking water. This challenge is marked by a notional interest in piped water for achieving service level goals while increasing demand and financial viability. Yet, a paucity of reliable information and evidence perpetuates unrealistic assumptions of how infrastructure and payment collection alternatives influence seasonal revenue generation. The emergence of professional service delivery models offers new sources of operational and financial data with potential to address knowledge gaps and inform viable, resilient, and equitable drinking water investments.
The primary aim of this project is to understand how seasonal patterns of domestic water use and payments affect revenue from piped water services in rural Africa. Empirical analyses have drawn on longitudinal records from Ghana, Kenya, Malawi, Rwanda, Tanzania, and Uganda that cumulatively span more than 500 service-years. In contrast to conventional assumptions, findings suggest household-level services exhibit similar seasonal revenue variability as off-site services and are not consistently associated with higher revenue when tariff level is controlled. Piped service areas with consistent seasonal rainfall have a third less revenue during wet months. Furthermore, prepaid credit payments do not consistently improve revenue generation compared to conventional payment approaches.
Three recommendations for rural water policy and practice are highlighted from this research. First, the threat of seasonal revenue variability to rural piped water services can be characterised by assessing rainfall patterns on localised, intra-seasonal scales. Second, complementary revenue patterns of on- and off-premises services can be leveraged at incremental stages of infrastructure investment. Third, caution should be exercised when considering prepaid credit over conventional payment approaches to prevent unrealistic revenue expectations and perverse outcomes.
Safer (cyber)spaces: reconfiguring digital security towards solidarity
Keywords: coercive control
participatory action research
technology abuse
surveillance
feminism
solidarity
domestic violence
cybersecurity
migrant domestic workers

As technology increasingly mediates our relationships, it also enables existing patterns of coercion, abuse, and control. This thesis investigates digital safety and security in the context of intimate violence and coercive control. I first develop a feminist critique of cybersecurity: namely, that due to the discipline’s engineering focus on defending networks and information, cybersecurity neglects the human element, and particularly differences in power and relationships between humans that produce (in)security. Feminist and critical theories, which centre gender and power in interpersonal relationships, provide a useful corrective to this highly masculinised and avowedly apolitical field. Taking this critique as a starting point, I present a set of studies that answer the overarching research question: “how can we reconfigure cybersecurity to account for tech-facilitated coercive control?” I focus on responses to the phenomenon of technology-enabled coercive control, or ‘tech abuse’ as a site for examining alternative security practices.
I then present three studies that reconfigure cybersecurity through running participatory workshops with excluded and marginalised groups, interviewing advocates who support survivors of technology abuse and addressing intimate violence in cybersecurity design. The model of cybersecurity that emerges from these studies is relational, made up of communal ‘networks of care’ rather than devices and individuals. This carries weight for questions of epistemology and academic knowledge production; my work centres the knowledge of unconventional and unacknowledged experts, such as survivors of abuse and community practitioners who support them. These people are cybersecurity experts due to their on-the-ground understanding of how technology is co-opted for abuse. Security practitioners should recognise the expertise inherent in these care networks to build on and strengthen them with a mindset of solidarity rather than turning these social problems into opportunities to pitch new technical products. Cybersecurity which starts with people (not machines), especially marginalised people, points our attention to dismantling the broader structures that create insecurity rather than patching technical vulnerabilities. In doing so, this reconfigured security becomes a call for solidarity.
The privilege against self-incrimination in England and Canada
Keywords: privilege
self-incrimination
incrimination
Canada
England

Historically, the concept of protection against testimonial self-incrimination was not an inherent part of the English system of justice. Formal oaths and formal acts to be performed by the defendant were a part of both civil and ecclesiastical trials. The only procedural protection that existed was the requirement that there be "due presentment", i.e., there had to be a specific charge and the solemn accusation before the defendant was required to make any response. When the Church, and subsequently the Star Chamber, adopted an inquisitional procedure, due presentment was by-passed, and there was a great outcry by dissenters. Gradually, the inquisitorial procedure became the focal point of opposition to church and state, and the phrase nemo tenetur setpsum prodere, which formed part of a Statement of law relating to due presentment, was snatched from its context and used as a slogan of the revolution. Common law courts supported the development of the privilege because it provided a means of controlling the jurisdiction of their rivals - the ecclesiastical courts. The fight against the tyranny of kings and bishops was successful, and the privilege became a fundamental rule of English trial procedure.
Canada inherited the privilege against self-incrimination from England, but in 1893 the right of a witness not to answer incriminating questions was abolished and replaced by a rule requiring an answer to be given while affording immunity against its use in subsequent proceedings. A comparison of the privilege in the two countries reveals that while the scope of the privilege is essentially the same, its actual operation is very different. Surveys conducted in conjunction with this research showed that the percentage of accused persons choosing not to enter the witness box is substantially higher in Canada than in England. Likewise, the Canadian immunity provision is used much more frequently by witnesses in Canada than is the common law privilege by witnesses in England. The reasons for and the implications of this difference are examined.
Continued in thesis ...
Computational dissection of schizotypy: differential contingency weighting
Keywords: individual differences
computational modelling
contingency learning
schizotypy
psychopathology
learning theory

Schizotypy is a personality dimension related to psychotic experience, i.e., alteration of beliefs and sensory experiences, also is a liability for schizophrenia. In this dissertation I focus on schizotypy and its relationship with perceptual, learning, and agency. I employed computational models, and Contingency Learning Theory as a general framework, to develop novel behavioural tasks used to dissect cognitive features of schizotypy measured in the general population.
I studied the Jumping-to-Conclusions bias with a novel perceptual contingency task (Experiment 1). This task also tests the tendency to perceive associations between events. I found that people scoring high on schizotypy does not perceive associations easily, but they gather more sensory evidence to make correct decisions. In addition, I investigated whether schizotypy moderates how people use absent information to make judgments (Experiments 2 and 3). In an exploratory analysis, I found that high unusual experiences scores were negatively correlated with how people use the absence of events to judge event relatedness. Moreover, I developed a framework −behavioural paradigm and computational model− to study how two agents (one human and one artificial) interact and make judgments of control (Experiments 4 and 5). I used this task to study illusion of control and how people weight external and internal events as sources of control. I found that people scoring high in positive schizotypy have an enhanced illusion of control when estimating their control. Although, this result is dependent on participants not ‘interacting’ with another agent. I also found that unusual experiences in schizotypy negatively correlate with sensitivity to external controllers (or agents).
In summary, I found that weighting sensory evidence varies in relation to schizotypy. This was supported with my results showing a bias to gather more evidence, a weight reduction for absent information, an enhanced illusion of control when there is nothing else competing for the control, and a reduced sensitivity to perceived control from another agent. Together, my results indicate that high positive schizotypy is related to downweighting sensory evidence with a low saliency baseline (absence of target information, and other agents). Finally, I explored the differences in the concept of weight in computational modelling and I conclude that mathematically different models refer to a similar mechanism, a value multiplying a discrepancy learning signal.
The demographic pathways of intergenerational transmission of educational attainment ----- the role of fertility and assortative mating in status reproduction
Keywords: fertility
education
family demography
social reproduction
assortative mating

The intergenerational transmission of education examines to what extent has one generation's attainment determined the next generation's attainment. It is deemed an important indicator of social fluidity and inequality. This thesis explores the demographic pathways of intergenerational transmission, focusing on fertility and assortative mating. It includes four self-contained essays, two on fertility and two on assortative mating.
Chapter One brought the previous individual-level inquiries on the relationship between sibship size and educational attainment to the societal level. Using the case of China, findings show that fertility decline during its One Child Policy era brought modest improvement in the average educational attainment of the country. However, differential fertility rates by rural/urban residency have a marked impact on rural/urban educational inequality.
Chapter Two examined the role of fertility in three-generational transmission. It proposed a new moderator for the process: the fertility rates of the grandparents. Findings using data from the Panel Studies of Income Dynamics (PSID) show that having multiple children (i.e., multiple members in the parental generation) amplifies grandparents' influence on grandchildren's educational attainment.
Chapter Three examined the role of parents in adult children's marital sorting. It extends previous findings on first and new marriages from a life course perspective. Results using PSID data show divergent trends by gender. Parents' influence becomes less important for males but more vital for females over the life course.
Chapter Four examined the role of education homogamy in intergenerational reproduction. It brought the previous one-sided analysis, which focused on one parent only, to the couple level and proposed an approach that is the first to consider and distinguish two sources—resource combination and family milieu—that generate the difference between homogamy and heterogamy. Findings using PSID data demonstrate that these two sources affect couples' probability of having children and their children's educational attainment differently, and their influences change over cohorts.
Construction of gene coexpression networks and transcriptomic analysis for Rhizobium leguminosarum
Keywords: Rhizobium leguminosarum
correlation
transcriptomics
nitrogen fixation
gene coexpression
networks

Rhizobium leguminosarum is a soil bacteria which infects plants of the legume family such as peas, lentils, and beans. When associated with the plant, R. leguminosarum fixes atmospheric nitrogen (biological nitrogen fixation), producing ammonium that is assimilated by the plant, improving plant growth. This symbiotic relationship is very important for agriculture; increasing the knowledge of plant infection and nitrogen fixation processes might lead to a decrease in the use of chemical fertilisers.
In this thesis, I combine R. leguminosarum gene expression data from previous experiments to produce gene coexpression networks and increase the functional annotation of this bacterium. Gene coexpression networks are networks in which nodes represent genes and edges represent coexpression (i.e. two genes are connected if they have a similar expression pattern). Unfortunately, there is no standard method to generate gene coexpression networks from gene expression data. I introduce signed distance correlation as a measure of dependency between two variables and use it to generate self-consistent, unweighted and weighted, gene coexpression networks that are more stable and capture more biological information than those obtained from Pearson correlation or mutual information.
Subsequently, I present a pipeline that combines novel scores from gene coexpression network analysis in a principled way to identify the genes that are associated with certain growth conditions or highly coexpressed with a predefined set of genes of interest. This association can lead to putative functional annotation or to a prioritised list of genes for further study.
Lastly, I provide a detailed analysis of the transcriptome of R. leguminosarum. For this purpose, I generate different knock-out mutants lacking transcriptional regulators which are reported to be important in the nitrogen-fixing state of the bacteria and perform RNA-Seq experiments. I also carry out a preliminary study of the molecular signals that may affect the changes in gene expression between the free-living and the plant associated bacteria.
Economic diversification, entrepreneurship, and regime stability in Saudi Arabia and Nigeria
Keywords: resource curse
corporate law
Saudi Arabia
regime stability
Nigeria
entrepreneurship
autocracy
comparative politics
economic diversification

Why do political elites in resource-wealthy autocracies and hybrid regimes pursue regulatory liberalization at certain moments, but not others? Within academic debates over the beneficial or deleterious effects of resource wealth, scholars have used quantitative methods to evidence a resource curse through a positive relationship between oil rents and the regulation of private enterprise. This dissertation charts a departure from this received wisdom using a paired, qualitative comparison of the politics of corporate regulation within the largest oil producers in Africa and the Middle East—Nigeria and Saudi Arabia. Drawing from a broader array of legal and bureaucratic reforms, and considering their heterogeneous implementation, I demonstrate that oil rents have played a crucial role in facilitating the liberalization of business creation regulations in the 21st century. Without the necessary oil rents to placate diverse threats to regime stability, particularly during the 2014-2016 oil price downturn, liberalization was inhibited. I term this the rent-conditional reform (RCR) theory.
Before applying the RCR theory to the case countries, I explore the politics of corporate regulation within the two cases in historical perspective. Drawing from archival documents, this dissertation illustrates the distinct but parallel politicization of corporate regulation in the 20th century. While corporate regulation was politicized through the introduction of a Western-origin corporate code in Saudi Arabia in the 1930s, it was conversely politicized in Nigeria in the late 1980s through the first indigenous reform of the country’s corporate code. Moreover, I forge a theory of interest groups in Nigerian politics to explain the cross-class, cross regional collective action in the corporate regulatory reform and administration processes.
Employing interviews with political elites, entrepreneurs, and bureaucrats in Nigeria and Saudi Arabia, I build upon these historic analyses to apply the RCR theory to the two cases before, during, and after the 2014-16 oil downturn. Using process-tracing, I argue that crumbling elite cohesion during the downturn disincentivized corporate regulatory liberalization in Nigeria, while the threat of popular unrest in the wake of the Arab Spring provided a parallel disincentive in Saudi Arabia during the same period. Together, the distinct causal processes across the two cases illustrate the applicability of the rent-conditional reform theory across diverse contexts of natural resource rent volatility.