VictorJuiz/thesis huggingface dataset:
Symmetric nonaqueous flow batteries with porous separators

Symmetric flow batteries use a single electrolyte formulation instead of the usual two and offer simplified manufacture and operation, the possibility to use low-cost porous separators in place of ion-exchange membranes, and elimination of certain failure modes. Furthermore, using nonaqueous solvents in lieu of water enables exploration of redox species that support cell potentials beyond the electrochemical window of aqueous electrolytes. This thesis aims to assist in minimizing the levelized cost of storage for symmetric nonaqueous flow batteries through informed electrolyte development, materials selection, and device operation.
Illustrating the large design space of flow battery electrolytes permits the definition of symmetric'' for the present application. A zero-dimensional model for flow batteries with porous separators is developed which incorporates self-discharge behavior. Coupling this model to technoeconomic equations reveals the basic tradeoffs inherent to using porous separators along with two promising active species approaches for symmetric flow battery electrolytes: salts of coordinated transition metal-ligand complexes and synthetically simple, soluble aromatic compounds used in a mixed electrolyte configuration. The technoeconomic analysis explores membrane cost/performance tradeoffs pertinent to symmetric systems using porous separators.
Successfully implementing symmetric electrolytes of any composition requires original approaches to measurement and control of transport phenomena in the membrane due to shifts in relative contribution of different driving forces for crossover and self-discharge vs. traditional flow batteries. Real-time estimation techniques and reservoir balancing methods are developed to measure and control these convoluted phenomena. Common perceived failure modes of benchtop flow batteries and methods to deconvolute capacity fade mechanisms are discussed.
The established nonaqueous redox-active species vanadium acetylacetonate is used as a representative compound to demonstrate that, counter to current literature, the primary failure mode of nonaqueous flow batteries is confined to resistance growth in the separator and not electrolyte or electrode degradation. Methods to further understand and mitigate this failure mode are discussed, and solubilities of cosolvent systems are explored to improve energy density. Iron bipyridine salts are revisited and found to succeed in symmetric flow battery operation subject to separator degradation constraints, prompting the study of more affordable counteranions.

Keywords: membrane fouling
redox flow battery
porous separator
electrochemical engineering
iron bipyridine
membrane
flow battery
nonaqueous electrochemistry
rfb
vanadium acetylacetonate
Self-supervised video representation learning

Videos are an appealing source of data to train computer vision models. There exist almost infinite supplies of videos online, but exhaustive manual annotation is infeasible. The goal of this thesis is to learn strong video representations efficiently via self-supervised learning: a method that learns from the data rather than human annotations.
The thesis is structured around three themes: (1) self-supervised learning for short-term videos, (2) efficient video representation learning, and (3) self- supervised learning for long-term videos.
For short-term videos lasting only a few seconds, we show that predicting the video in the future is a strong learning signal at a large scale. We further show that strong video representations can be learned by taking two complementary modalities, namely RGB and optical flow, and using them to teach each other.
For efficient video representation learning, we show that large-scale pre-trained vision-language models can be effectively adapted via a prompt tuning technique. We also show that dropping image patches can accelerate the finetuning of classification tasks and pre-training of video-language models.
For long-term videos that last longer than a few minutes, we show that temporal alignment networks can be trained from the weak visual-textual correspondence within instructional videos. The resulting networks can automatically clean up the natural videos for effective vision-language training. In addition, we show that movie description models can be trained by leveraging the pre-trained vision- language models.

Keywords: video understanding
self-supervision
deep learning
efficient learning
Advisor: Zisserman, A
Copyright isn't for everyone: copyright formalities as a response to authors' needs in the digital age

The online environment has empowered authors to act on intrinsic and non-commercial motivations for creating and disseminating works in unprecedented ways that conflict with copyright􀂶s exclusivity. While all-rights-reserved copyright remains vital to traditional content industries, it is no longer suitable for non-traditional online creators who aim for their works to reach the widest possible audience. The resulting misalignment between copyright law and the terms on which authors wish make their works available—unreliably mediated by social sharing norms and tolerated use—not only deters mutually beneficial content use but risks undermining copyright's credibility as authors implicitly encourage infringement. To remedy this, authors must be given effective control over their works' availability. It is not enough to permit authors to opt out of copyright protection, as this cannot assist creators unaware that copyright attaches to their works. A radical new solution is needed.
This paper proposes ‘Copyright 3.0', a bifurcated copyright system providing modest default rights meeting the average creator's needs (moral rights and protection against commercial use), while enabling authors to flexibly ‘level up' or ‘level down' protection through registration and notice formalities. The default rights would ensure works are never left vulnerable to unjust exploitation, while the burden of opt-in formalities would fall only on those with the most to gain, who can fairly be expected to bear it.
This proposal deviates from the pro-formality literature of the last two decades by arguing for formalities' reintroduction from an authors' rights perspective, rather than a public interest perspective. This makes it uniquely defensible, as the proposed limitations to authors􀂶 automatic entitlements are designed specifically to empower and protect authors. While Copyright 3.0 conflicts with article 5(2) of the Berne Convention, it is the best available mechanism for tailoring copyright to authors' needs, and aligns with authors' and users' common-sense expectations.

Keywords: copyright registration
copyright
Advisor: Burrell, R
Essays on international trade and globalisation

This thesis contains three papers on globalisation and its effects. The first two chapters study the labour market impacts of international trade in contrasting contexts. Chapter One uses the recent surge in Chinese export growth to study the effects of a manufacturing trade shock on workers and firms in the UK. Using micro data on both workers and firms, it shows how the trade shocks effects materialise at worker, firm, and industry dimensions, as well as how the impacts vary across types of workers and firms. The second chapter focuses on international trade in services. Services trade has grown rapidly in the past few decades and differs from manufacturing in terms of the nature of trade and the types of workers more affected by trade. I use detailed UK micro data to estimate the impact of the growth in imports of services on labour market outcomes, including the heterogeneity of the effects across the wage distribution. The final chapter is more distinct and documents the huge extent to which international tax loopholes influence flows of foreign direct investments. Using administrative data on foreign investments received by Indian firms, it estimates the impact of a reform to a bilateral tax treaty between India and its largest foreign investor Mauritius.

Keywords: FDI
globalisation
international trade
wages
foreign direct investment
offshoring
bilateral tax treaties
services trade
China shock
multinational enterprises
international taxation
Advisor: Bond, S
Cognitive factors in adjustment after social trauma

This project uses mixed methods to investigate cognitive and behavioural factors associated with social anxiety disorder (SAD) and posttraumatic stress disorder (PTSD) symptoms among young people who have been bullied. The aim is to explore the social trauma of bullying, investigate factors that increase vulnerability to ongoing emotional distress, and develop bespoke measures that are clinically useful and statistically robust.
Following a general introduction in Chapter 1, this thesis is structured into two main sections. In the first section, I present four studies exploring and evaluating factors associated with adjustment after bullying. In Chapter 2, longitudinal analysis of a large prospective cohort study shows that children who were severely bullied and have an external locus of control are more likely to experience a steeper increase in social fear during early adolescence compared to those with an internal locus of control. The following chapters describe development and validation of measures of bullying-related cognitions and coping strategies associated with PTSD and social anxiety among young adults. Chapter 3 reports pilot data on cognitive themes related to bullying that are associated with SAD and PTSD symptoms and suggests the online survey format is acceptable. In Chapter 4, qualitative analyses of semi-structured interviews with young adults about their experiences of bullying and their past and ongoing reactions suggest additional themes that may be associated with higher ongoing symptoms. Chapter 5, the last in this section, draws these findings together and describes statistical evaluation of new measures of cognitions and behaviours related to bullying which were derived from the previous studies. Data is from an online survey study with over a thousand young people starting university or college in the UK. The newly developed measures were reliable and valid, defined as the Bullied Cognitions Inventory, Bullied Social Attitudes Inventory, and the Bullied Social Behaviours Scale. In the second section, associations of the new cognitive and behavioural measures with SAD and PTSD are tested. Chapter 6 reports the extent to which these measures distinguish between SAD, PTSD, or no likely clinical diagnosis in the online survey data. Participants in this study were invited to complete three additional surveys during their first year of university and, in Chapter 7, longitudinal analyses are reported that explore changes in PTSD and SAD symptoms and the extent to which the new measures can predict differing outcomes.
Together, these studies highlight the social trauma of bullying and identify cognitive and behavioural factors associated with SAD and PTSD symptoms among young adults who have been bullied. Psychometrically validated scales suggest themes that distinguish between symptoms as well as transdiagnostic features. Results and limitations are discussed, as well as suggestions for clinical application and future research.

Keywords: bullying
posttraumatic stress disorder
cognitive interventions
social anxiety disorder
Advisor: Ehlers, A
Bowes, L
Investigating the non-protein binding targets of the Teneurin extracellular domain and their biological significance

The adhesion protein teneurin is known to control brain development and neuronal migration. Much of the research centered around teneurin thus far has probed its protein binding partners, of which the aGPCR Lphn, and FLRT protein are most extensively studied. One as yet understudied binding partner of the teneurin extracellular domain are the glycosaminoglycan (GAG) macromolecules abundant in the brain extracellular matrix (ECM). These highly charged glycans are made up of five main families: Heparin/ Heparan sulfate (HS); Chondroitin sulfate (CS); Dermatan sulfate; Keratan sulfate; and Hyaluronic acid. These glycans, specifically HS and CS species, have been shown to be important modulators of neuronal migration, as well as factors dictating CNS plasticity and trauma recovery. The work in this thesis proves that binding of HS and CS ligands occurs on a highly charged patch on the large YD-shell scaffold which forms the majority of the teneurin ecto-domain. Two crystal structures were solved here with glycan ligands, proving the binding site contacts 6 Arginine and Lysine residues on the teneurin surface. Subsequent mutation of this binding site abolished binding, and was confirmed by pulldown assay. In vitro cell based migration assays began to unearth the effects of glycan binding of HEK and N2A cell migration, with a view to the effect of glycan binding in the developing brain. This work illustrates the first time teneurin–glycan complexes have been investigated structurally, and represents an introduction into the study of glycobiology with respect to teneurin and how this may control neuronal development.

Keywords: structural biology
biochemistry
glycans
crystallography
Advisor: Seiradake, E
El Omari, K
Probing the timeline for the acquisition of altered circuit function in the developing prefrontal cortex

Neurodevelopmental disorders are characterised by cognitive and behavioural deficits, which are underpinned by a broad spectrum of neural deficiencies in brain regions critical for higher-order cognition - more specifically, the medial prefrontal cortex (mPFC). The mPFC is involved in learning, memory, and decision-making, and its appropriate functioning in adulthood depends on the correct balance between excitation and inhibition established during early neural development.
GABAergic interneurons are critical components of cortical circuits where they modulate the firing of neurons and thus control information flow both in adult and developing cortical networks. The early circuits of the mPFC exhibit characteristic discontinuous oscillatory patterns in the beta and gamma frequency ranges. The precise characteristics of these early beta and gamma oscillations are unknown as well as how they relate to the activity of single neurons.
Here, we (1) explored the early oscillatory activity in the developing mPFC, (2) we examined the activity of single neurons during development, and (3) we characterised the specific interactions between beta and gamma oscillations and single neurons - with a focus on PV+ and SST+ GABAergic interneurons.
We recorded extracellularly from anaesthetised and awake animals and found that anaesthesia affects beta but not gamma oscillations and that both beta and gamma oscillations change over development - with a possible critical period at postnatal day (P) 12. Single neurons were also found to change their features during development and in anaesthesia. Through optotagging, we identified putative SST+ and PV+ interneurons and found that they differentially contribute to beta and gamma activity, as do other single neurons - with a possible critical period also at P12.
These findings shed light on the early oscillatory and single neuron activity in the mPFC and inform further investigations on the origins of neurodevelopmental dysfunctions in brain regions critical to higher-order cognition.

Keywords: brain development
interneurons
in vivo electrophysiology
prefrontal cortex
Advisor: Butt, S
Lak, A
Behavioral and neural signatures of information sampling to guide economic choice

Humans have an extraordinary capacity to seek out novel information relevant for current and future goals. However, the use of simple choice tasks in decision-making research in which participants are not able to sample information freely has limited our ability to investigate the drivers of information sampling and their neural signatures. In this thesis, I present findings using active information sampling tasks combined with functional magnetic resonance imaging (fMRI) data and large-scale online participant samples.
We find that activity in areas of medial frontal cortex (MFC) and parietal cortex predict upcoming decisions to sample in a multi-step decision-making task with active sampling. Furthermore, a large network of brain regions is shown to represent key features of sampled information.
I then describe the development of a novel information sampling task, in which hypothesized drivers of information sampling can be manipulated. Running many pilot task versions on online participants reveals sampling behavior to be heterogeneous and the existence of many sampling strategies.
A version of this task was used in combination with psychiatric questionnaires to investigate the link between compulsivity and information sampling in a large-scale online study. We find evidence for an effect of compulsivity on the integration of task features to drive sampling, but this is not replicated in a confirmation sample.
Finally, another version of the developed task was used in combination with fMRI to investigate the neural signatures of different drivers of sampling. One driver of sampling was represented in brain activity: goal proximity. We find a similar pattern of brain activity predictive of upcoming decisions to sample, but this effect does not reach significance in MFC.
The work in this thesis shows that areas known to frequently activate in decision-making tasks are likely to also drive information sampling to satisfy upcoming goals.

Keywords: fMRI
decision-making
information sampling
neuroscience
Advisor: O'Reilly, J
Hunt, L
A computational and empirical perspective on gendered correlates of heterogeneous childlessness: Micro-level inequalities, meso-level networks and macro-level developments

This thesis investigates childlessness across time and levels of socio-economic development as well as its pathways and consequences in individual life courses, and the role social network influences play in connecting the two. Throughout three standalone but related papers, this thesis first examines the gendered relationship between childlessness types and development components in sub-Saharan African subnational regions using hierarchical modelling and Demographic and Health Surveys data. Second, it proposes a Bayesian hierarchical growth curve modelling approach, using 1970 British Cohort Study data, to assess the accumulation of socio-economic (dis)advantage throughout the life courses of parents and permanently childless men and women. Third, it investigates the role of structural and compositional characteristics of social networks in the interaction between individual-level childbearing behaviour and aggregate childlessness patterns using agent-based simulation models calibrated to Dutch data and emulated by statistical and machine learning models. This thesis contributes to the literature by examining childlessness from the interconnected micro-, meso-, and macro-level perspectives; acknowledging the heterogeneity regarding gender and reasons for childlessness; and applying advanced methodologies to overcome current modelling limitations. The findings suggest that in developing regions, macro-level decreases in involuntary childlessness and increases in voluntary and circumstantial childlessness may be explained by educational, income and health advancements. In developed regions, remaining childless may contribute to the accumulation of socio-economic (dis)advantage throughout individuals’ life courses. Decreasing abidance to social norms through increasingly individualistic meso-level social networks may connect macro-level childlessness norms and patterns which emerge from and sequentially influence micro-level childbearing values and behaviours. Contextual factors on the micro-, meso- and macro-levels, such as marriage and employment, influence the direction and magnitude of the observed associations. The findings have societal and policy implications regarding the viability of populations and welfare states; equality by both parental status and gender; and public perceptions of childlessness.

Advisor: Monden, CWS
Probability models of population structure and gene flow

There is a substantial interest in the relationship between population structure and the patterns of genetic variation. In structured populations, these patterns heavily depend on gene flow, the movement of genetic material from one population to another.
In spatially structured populations, gene flow can be quantified by the spatial motion of ancestral lineages — the description of where the ancestors of modern individuals lived at times in the past. Understanding the stochastic motion of these lineages is key to explaining patterns of genetic variability. In Chapter 1 we describe a new model for a population evolving on Zd in which the demographic parameters of subpopulations depend on the population density in a local neighbourhood. After suitable scaling, tracing numbers of adults in the population we arrive at a system of interacting SDEs. The motion of a lineage ancestral to an individual sampled from such a population follows a random walk in a random environment and we establish this motion in the scaling limit. In contrast to classical models in which ancestral lineages are drawn into regions of high population density, in our setting, a lineage is attracted to regions of high fecundity.
In Chapter 2 we study the movement of ancestral lineages in a model in which local population sizes are determined by the presence of transient, patchy resources. Habitats are either bad or good and population sizes in good habitats are so large that, given the opportunity, lineages will always move from bad to good habitats. Lineages traced back through time can be explicitly described and we highlight the role of the spatial and temporal autocorrelation structure in determining the behaviour of lineage movement. The typical displacement between an individual and their ancestors may differ substantially from that predicted based on typical offspring dispersal.
Population structure need not be spatial; eg in some species, mating is restricted to occurring between individuals from distinct self-incompatible classes, termed mating types. Gene flow between these classes occurs only at the times of rare bouts of sexual reproduction. The evolutionary mechanism that drove the establishment of self-incompatibility is still a debated topic. In a new approach, in Chapter 3 we address this by quantifying the population genetic diversity and the probability of ‘effectual sex’ as a function of the number of self-incompatible classes. Our results permit a novel understanding of the early origins of sex.

Advisor: Etheridge, A