VictorJuiz/thesis huggingface dataset:
Synthesis and characterization of molecular wires with small bond-length alternation
Keywords: organic synthesis
cumulene
molecular electronics
cyanine dye

This thesis presents the synthesis, characterization, and single-molecule charge transport studies of two families of molecular wires, cumulenes and cyanines, both of which have small bond-length alternation (BLA) in their linear conjugated systems. Normally, the single molecule conductance of a family of molecular wires will decrease as the molecules become longer, which would hinder the molecular wires from mediating long distance charge transport. Our experimental and computational studies showed that a small BLA contributes to more efficient charge transport through molecular wires.
Chapter 1 introduces the research field of molecular electronics, including the main techniques for studying single-molecule charge transport, scanning tunnelling microscope break-junction (STM-BJ) and mechanical controlled break-junction (MCBJ), and the mechanism of charge transport through single molecules. We also discuss how BLA influences the conductance of the molecules.
Chapter 2 introduces our research into cumulene molecular wires. Cumulenes are molecules with consecutive double bonds. We synthesized a family of cumulene molecular wires, with 1, 2, 3 and 5 consecutive double bonds, then studied their charge transport properties by the STM-BJ technique and DFT calculations. Our results showed that the [3]cumulene and [5]cumulene have essentially the same conductance, suggesting that the structure of consecutive double bonds contributes to higher conductance of the molecular wires. We attribute this to the small BLA, which leads to a smaller HOMO-LUMO gap in cumulenes.
Chapter 3 introduces our research into cyanine dye molecular wires. Cyanines are molecules bearing a positive charge, which have ending groups connected by an odd-numbered polymethine bridge. For the short cyanine dyes, their positive charge fully delocalises through the molecule, leading to a ground state structure without BLA. When the molecules become sufficiently long, their positive charge starts localizing at one of the end groups, thus the ground state structure shows BLA in their polymethine chains. We synthesized a family of cyanine dye molecular wires, with 3, 5, 7, 9 and 11 carbon atoms in their polymethine chains, with PF6- and B(C6F5)4- as counter ions, then studied their charge transport properties by the STM-BJ technique and DFT calculations. All cyanine dyes showed similar conductance, except the Cy11·PF6, which has a lower conductance. Combined with the UV-vis-NIR spectroscopy and crystallographic studies, we conclude that a Peierls transition happens in the Cy11·PF6 molecular wire, leading to charge localization and a lower conductance of the molecule.
PMT studies and loop antenna development for the LZ dark matter experiment
Keywords: LZ
Dark Matter

The nature of dark matter remains one of the biggest mysteries of the universe. Extensions to the Standard Model of particle physics provide potential candidates for dark matter. Such dark matter particles can be searched for using direct detection experiments. LUX-ZEPLIN (LZ) is a next-generation search for dark matter currently under construction at SURF, South Dakota. LZ employs a two-phase, liquid xenon time projection chamber (LXe TPC). A dark matter particle would scatter of a xenon nucleus, which causes scintillation and electroluminescence light signals. The light is detected by Photomultiplier Tubes (PMTs) on the top and bottom of the detector. The sensitivity projection for a 1000 live day run with 5.6 tonne fiducial mass is 1.6 x  10-48 cm2for a 40 GeV/c2 mass WIMP at 90% confidence level.
The first part of this thesis is concerned with the precise modelling of PMT properties and their impact on detector performance. To optimise sensitivity to WIMP masses of less than 10 GeV, it is essential to understand the single photon PMT response in detail. A simulation model, including undersized PMT pulses, is developed based on data taken with spare LZ PMTs. Variation in the PMT single photon response impacts detection efficiencies, energy resolution and position reconstruction. The improved PMT simulation is used to assess the impact of PMT failures on LZ signal detection efficiency, signal to background discrimination and ultimately LZ sensitivity.
High voltage discharges, accompanied by sparks, are a potential danger to the PMTs and a known problem in liquid noble gas detectors. The second part of this thesis discusses the development of the first dedicated high voltage discharge monitoring sensor in a LXe TPC. The loop antenna provides useful information about the electromagnetic environment of the detector and monitors for such discharges.
Inkjet printing of liquid crystals and polymer composites for novel thin-film optical elements
Keywords: printed displays
microlenses
Inkjet printing
fabrication of optical thin film elements
3D printing
smart windows
additive manufacturing
liquid crystals

This thesis investigates the drop-on-demand inkjet printing of liquid crystal (LC) inks, from drop formation and deposition, through to substrate selection. Inkjet printing is a particularly attractive fabrication method as it is a precise, scalable and highly cost-effective additive manufacturing process. These benefits, along with the ability to deposit pico-liter volumes of particulate suspensions, viscous and complex fluids, have led to inkjet printing being considered as an attractive alternative fabrication technique in a range of established fields such as the display, pharmaceutical and bioengineering industries. However, the unique considerations of using liquid crystalline inks, such as their anisotropic properties and alignment criteria is barely touched in the literature. This thesis describes the design and build of an inkjet printing system capable of depositing a range of different functional inks such as LCs and polymer solutions. Drop generation of a nematic LC in a piezoelectric printhead and the role of different printing substrates on the final droplet configuration is considered in detail. This knowledge is used to fabricate novel, variable-focus microlens arrays that can be deposited as pre-programmable arrays on to a variety of different substrates. The unique properties of inkjet printing are then leveraged to describe two new methods of producing patterned, single layer polymer dispersed LC films. A prototype switchable, patterned polymer-dispersed LC film, produced by inkjet printing, is demonstrated. This work shows the feasibility of inkjet printing LC and polymer formulations and has important technological implications in the manufacturing of small and large area, polymer dispersed LC films for a variety of applications.
Deterritorialising climate: ocean-based approaches to adaptation governance

Keywords: climate change
Timor-Leste
Pacific adaptation governance
ENSO
ocean ontologies

This research asks how the Pacific climate system of El Niño Southern Oscillation (ENSO) is conceived and represented in the boundary-making practices of three knowledge communities: a) ocean science (i.e. Pacific marine biogeographies), b) environmental governance (i.e. Pacific adaptation frameworks), and c) local and traditional environmental knowledge (i.e. coastal subsistence communities in Timor-Leste). Ultimately, the project asks whether these disciplinary delineations of ENSO-related climate events promote effective adaptation governance.
There are four main findings: the ontological foundations of environmental law and governance frameworks work against fundamental aims in climate adaptation governance; there is an imperative to decolonise environmental law and governance frameworks in postcolonial contexts; local and traditional practices offer alternative ways of delineating adaptive geographies; and, lastly, principles from marine scientific boundary-making practices could inform governance frameworks in conceptualising assemblages of environmental change that move over space and time.
The Wikipedia news network: understanding collective response to current events through the internet’s encyclopaedia
Keywords: News Media
Collective Attention
Social Networks
Encyclopaedia
Wikipedia

Wikipedia is the primary authoritative information resource on the web for billions of people, and perhaps the most important reference work in human history. Its modernised notion of the encyclopaedia is a widely accessible and rapidly updatable record for both historical knowledge and current events. The trove of available trace data from its users' browsing patterns also means that the site acts as an appealing, representative barometer for wider patterns of collective attention.
Studies of news media are often concerned with news values—properties of events—that together define newsworthiness—how likely an event is to be chosen for news coverage. In essence; what makes an event news? Traditional study, however, has frequently focussed on data directly from news media, journalists, or even news sharing on social media rather than independent "extra-media" data. This raises concerns of selection biases, platform-specific network effects, and endogeneity. To counter these issues I turn to Wikipedia and the way its users access its information for an audience-centric perspective on current events, news values, and newsworthiness.
In this thesis I conduct three studies designed around understanding collective response to current events. In the first study, I explore how events are represented on Wikipedia and accessed by is audience. To do this I develop a temporal community detection approach towards identifying the topics primarily browsed by users. Secondly, by combining the extra-media data of Wikipedia with a matched news article database I address and reformulate foundational hypotheses of news values and newsworthiness theory. In the third study, I more directly analyse the peaks of collective attention that emerge when a subject is in the news. I develop a time series clustering algorithm to identify the characteristic shapes of these peaks and propose a forecasting model for their growth and decay.
This thesis makes significant contributions to research on online representations of current events, modern understandings of news value theory, and models of collective attention dynamics. By not directly studying news media itself, this 'altmetric' style approach to studying the impact of news events is an important practical and theoretical advancement. It also has deep implications for newsrooms employing editorial analytics and for how platforms, including Wikipedia, serve content on current events to users. More widely, since newsworthiness and attention influence what information is popular—even acceptable—online, studies from novel, independent settings such as this are crucial to informing future journalistic and online speech policies and regulations.
Improving the surgical patient care pathway through use of activity monitoring                                 
Keywords: preoperative assessment
surgical pathway
activity monitoring
accelerometer
cardiopulmonary exercise testing
prehabilitation

We can now monitor the physical activity levels of patients in the perioperative period. This has several potential applications including preoperative monitoring to assess patient fitness, postoperative monitoring to assess patient recovery, and to measure the impact of interventions aiming to improve cardiorespiratory fitness.
The research presented in this thesis set out to explore the relationship between daily physical activity levels and a patient’s cardiorespiratory fitness, and how measurement of daily physical activity levels can be used to improve patient fitness. To this aim, I developed two clinical study protocols to explore the use of activity monitoring as part of the surgical patient care pathway. A secondary aim was to improve the usability of activity monitoring for measuring physical activity levels in this population of patients. For this, a physical activity classification method and a system of remote activity monitoring was developed.
I found that there was a relationship between summary measures of daily physical activity levels as measured using a wearable accelerometer and patient fitness levels as measured using cardiopulmonary exercise testing. A feasibility study was commenced and successfully recruited six patients into a randomised controlled study involving daily physical activity monitoring and remotely supervised exercise intervention. Analysis of accelerometer data was shown to be a useful measure of the change in patient physical activity levels over a period of four weeks. Qualitative analysis of patient interview data revealed themes relevant to development of behavioural change techniques to improve adherence to preoperative exercise intervention.
The results from the novel study presented in this thesis showed how activity monitoring could be used in the surgical care pathway. From my studies, I have also identified the benefits and limitations of accelerometer measured daily activity in both the assessment of cardiorespiratory fitness and as a remote supervision and patient behavioural change tool during prehabilitation.
Identification and characterisation of the type VI secretion system in rhodobacter sphaeroides
Keywords: T6SS
type VI secretion system
Rhodobacter sphaeroides

The type VI secretion system (T6SS) is a versatile multi-component nanomachine found in 25% of Gram-negative bacteria. It translocates effector proteins into neighbouring eukaryotic or prokaryotic cells, and therefore it is important for bacterial virulence, as well as interbacterial competition. Although initially T6SSs were considered to be primarily contact-dependent weapons de- ployed during bacterial warfare, recently T6SSs that secrete effector proteins to sequester common goods from the environment have also been identified. Characterised examples of such systems play a role in the uptake of zinc, manganese, iron, copper and molybdate ions. The mechanism behind T6SS- dependent metal ion acquisition involves secretion of a metal-binding protein which sequesters metal ions from the extracellular milieu. The subsequent steps by which cells uptake the sequestered metal ions remain largely elusive, nonetheless it it is known that, in some cases, interaction of the secreted protein with a TonB-dependent outer membrane transporter is required.
Here we report the previously uncharacterised T6SS of Rhodobacter sphaeroides WS8N. By performing bioinformatic analyses on the putative T6SS cluster we find that it encodes all 13 core T6SS proteins along with four proteins known to be involved in T6SS regulation (TagE-H), the T6SS tip sharpening protein PAAR, the peptidoglycan-binding protein TagL and an additional seven hypothetical proteins. We also find the presence of a T6SS to be strain, and not species, specific in the Rhodobacteraceae family of proteobacteria.
Further, we investigated the conditions under which the the T6SS of R. sphaeroides WS8N is active and demonstrate that, its function is required for photoheterotrophic growth under iron-limited conditions. In particular, presence of this T6SS allows growth of R. sphaeroides WS8N in limited amounts of both Fe2+ and Fe3+, but does not support growth in iron-depleted media supplemented with heme. Finally, we performed preliminary biochemical studies of the C-terminal extension of VgrG, which showed the potential to bind iron. This suggests that VgrG might be the secreted protein facilitating the T6SS-dependent uptake of iron.
The data presented in this study represents the first characterisation of a T6SS from the Rhodobacteraceae family of proteobacteria, informing us on the role of this system in a class of organisms that heavily depend on the use of iron for their growth.
Opposition strategy-formation in autocracies: a theory of coordination with evidence from Latin America

Keywords: Opposition Strategies
Latin America
Venezuela
Autocracy
Political Parties
Democratization
Mexico
Coordination
Oppositions

When and why do oppositions coordinate their actions against authoritarian regimes? This dissertation studies uneven patterns of opposition coordination in autocracies. By paying attention to the individual and collective dilemmas of opposition elites, this research challenges existing knowledge and the assumptions that scholars bring to the study of non-democratic regimes. In contrast to existing accounts that mostly focus on the behaviour and choices of the autocrat, my project provides insights into the micro-foundations of the decision-making and strategy-formation processes of opposition parties. This work also makes a conceptual contribution to the existing theories of non-democratic regimes explaining when and why coordination is more likely to happen.
Based on 239 semi-structured interviews with opposition elites, academics, journalists, regime defectors, civil society members, amongst others, collected during iterative field research trips between 2014 and 2019 to the US, Mexico and Venezuela, this study hones in on repression as an explanatory variable for opposition strategic choices in autocracies. I have found that what shapes opponents’ decision-making and strategy-formation is the amount of repression they are facing and how repression is applied (targeted or indiscriminate). This dissertation disaggregates the concept of repression into violent and non-violent and singles out that the rulers deliberately choose who to repress and how much to repress to divide their opponents into irreconcilable camps. In a nutshell, this research argues that opposition coordination is only possible under two conditions: When repression is both moderate and indiscriminate. When repression is either low/high and/or targeted towards specific parties, coordination is less likely to occur.
A history of gold mining in the Asante region of Ghana (1950-1972)
Keywords: decolonisation
Mining communities
gold mining
gender
contested wealth
colonial capitalism
Asante

This doctoral research project addresses the significant lacunae in the inadequate inclusive understanding of Ghana’s gold mining history over the late colonial and early post-colonial period that encompass multiple socio-political actors in the industry’s encounters with state and society. The thesis examines the overarching contestations among multiple social and political actors over access to the potential benefits to be derived from mineral extraction within this changing socio-political landscape. It utilises a wide range of archival materials encompassing colonial and post-colonial state and mining companies’ records, combined with in-depth oral histories with diverse mining communities’ actors with lived experiences of these settings, dating to the mid-to-late twentieth century.
While the study period saw the dominance of industrialised gold mining with accompanied political-economic policies and socio-cultural norms that prevented artisanal mining operations in the study communities, access to the resultant industrially generated mineral wealth took multiple and diverse forms. It transcended the often-explored state-company-worker relations within the formal masculinised industrial extractive sector, and is here analysed in relation to a pluralist understanding of these mining communities. The thesis demonstrates the need to understand Ghana’s gold mining history during this period in an inclusive and nuanced way, emphasising the agency of diverse social and political actors ranging from elite political and economic actors from the colonial metropole to the national, and then to local subaltern members of mining communities, within a single analytical framework. Against the background that historical reality often defies the logic of rigid periodisation, the thesis provides an inclusive understanding of how these diverse actors navigated change and contested—albeit commonly in unequal ways—access to the benefits generated by mineral resources based on ideas that were both historically continuous and radically transforming during the period under analysis.
Adaptive robust model predictive control
Keywords: uncertain linear systems
Adaptive control
System identification
Model Predictive Control
control of constrained systems
Robust control

Model Predictive Control (MPC) repeatedly solves a finite horizon optimal control problem subject to input and state constraints. The performance of MPC algorithms depends crucially on the quality of the model that is used to optimize the predicted future performance. To reduce system model uncertainties, adaptive controllers have been proposed for MPC enabling model parameters to be identified online. Adaptive robust MPC, combining adaptive control and robust MPC, therefore has the potential to estimate system parameters while satisfying operating constraints and providing stability guarantees. However, although adaptive robust MPC algorithms have been considered for several decades, robust, computationally tractable adaptive MPC remains a topic under research.
This thesis proposes several adaptive robust Model Predictive Control strategies for linear and nonlinear systems with constant unknown model uncertainties and bounded additive disturbances. By combining set membership parameter identification with robust tube MPC, the proposed algorithms guarantee robust constraint satisfaction and recursive feasibility. Computational tractability is ensured by using polytopic sets of fixed complexity to bound parameter sets and predicted states. The closed-loop system is proven to be input-to-state stable under a nominal cost.
For parameter identification, the thesis proposes various approaches that incorporate persistence of excitation conditions as computationally tractable constraints with feasibility guarantees within adaptive MPC. Methods of ensuring persistence of excitation include augmenting the cost function, exploiting the random nature of disturbance inputs inherent in the model, introducing additional excitation into the control inputs, and including both disturbance and additional input excitation in the algorithm. The performance of various approaches is compared in terms of parameter convergence and tracking or regulation performance. In addition, the thesis relates the probabilistic rates of parameter set convergence to persistence of excitation conditions and proves convergence of the estimated parameter sets to the true parameter values using the proposed algorithms.