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Characterising gastrointestinal nematode populations and anthelmintic resistance in Scottish dairy calves
Get PDFGastrointestinal nematode (GIN) infections are ubiquitous in pasture-based grazing systems in the UK and worldwide, and are detrimental to animal health, welfare, and the productivity of livestock systems. These infections comprise coinfections with multiple species within a single host(s). Helminth species vary in epidemiology, pathogenicity, and anthelmintic sensitivity; however, the interactions among these parasites and the influence of management practices remain poorly understood. The most economically and clinically important GIN species infecting cattle in Europe are the abomasal parasite Ostertagia ostertagi and the smallintestinal-dwelling Cooperia oncophora, with the former being the more pathogenic.
To date, the control of GIN infections has primarily been achieved using three anthelmintic classes: benzimidazoles, imidazothiazoles, and macrocyclic lactones (ML), but over-reliance on treatment has inevitably resulted in the development of resistance. Although resistance in GIN of cattle appears to be developing more slowly than in nematodes infecting small ruminants, reports of resistance in the literature are increasing, suggesting an escalating problem.
For this reason, there is a pressing need to conserve anthelmintic efficacy and develop sustainable control measures. However, recommendations for sustainable parasite control in cattle are often extrapolated from sheep-based research, as cattle-specific research is inherently more challenging. The lack of sensitive tests for anthelmintic resistance limits research and surveillance. The purpose of this thesis was to advance understanding of the GIN communities infecting cattle on Scottish dairy farms, with a particular focus on characterising species composition and assessing anthelmintic resistance status. In vivo, in vitro, and molecular diagnostic approaches were used to characterise the GIN populations, and a genome-wide association study was used to identify genomic regions under ML selection within Os. ostertagi field populations. A longitudinal study examining the influence of management practices and anthelmintic treatment demonstrated that many of the established patterns of the most clinically important GIN species of cattle remain consistent when assessed using modern molecular techniques, despite the passage of fifty to sixty years and substantial changes in dairy farming practices since the original empirical studies.
The faecal egg count reduction test and egg hatch test highlighted the complexities involved in interpreting resistance tests, particularly with mixed species communities. These tests underscored the need for clearly defined criteria and thresholds if these methods are to be applied reliably in the field. Finally, the forward genetic approach identified a novel QTL associated with ML resistance on chromosome 5. The detection of this QTL in a major cattle parasite is the first major step toward understanding the genetic basis of ML resistance and will be used to advance our understanding of resistance in the field
Cavitating bubbles in focused fields: the acoustic emission spectrum and broadband noise clearance upon synchronisation
Get PDFThis thesis presents a set of studies that contribute to the understanding of bubble cavitation dynamics. Acoustic detection is the most commonly used method to monitor cavitation in microbubblemediated therapies such as blood brain barrier opening. However, the acoustic emission spectrum has been empirically correlated with safety and efficacy, and does not offer a complete understanding of the underlying bubble dynamics responsible for therapeutic effects. The combination of acoustic detection and high-speed imaging used in this work provides new insights into cavitation dynamics by correlating the acoustic signature with direct observations.
The first study compares the acoustic behaviour of a range of ultrasound contrast agent formulations driven by ultrasound with therapeutically relevant frequency and pressure amplitude. A polycarbonate capillary was used to observe single bubbles and record their acoustic emissions. It was found that the physical properties such as gas core, shell type and size had no distinguishable effect on the acoustic emissions and these are instead determined by the driving parameters. Bubble collapse shock waves dominate the acoustic spectrum, with their periodicity determining the spectral features observed. Precisely timed shock wave pulse trains provide harmonic and subharmonic content based on their period. A rise in broadband noise represents a break in periodicity which occurs as bubbles oscillate more chaotically when transitioning from one periodic regime to another.
The second study transitions to a multi-bubble system and observes the cavitation induced in the bore of a tube transducer driven with increasing pressure amplitude. A spectrogram of the cavitation emission signal collected over the duration of the ramped sonication confirms a subharmonic route to chaos; the progression from harmonic emissions to broadband noise via a period-doubling bifurcation. Stroboscopic mapping demonstrates that the emergence of broadband signal is due to increasingly asynchronous bubble collapse across the population and a region of sudden broadband clearing is explained by phase synchronisation of the bubble oscillations.
The final study demonstrates the importance of hydrophone deconvolution when assessing the spectral content of cavitation emissions. Not knowing the full frequency response of a hydrophone may lead to incorrect assessment of the cavitation spectrum. This work characterises the frequency response of a fibre-optic hydrophone and uncovers a spectral peak at 3.4 MHz using bubble collapse shock waves from laser-induced cavitation. This method found that the spectral peak could be reduced by decreasing the length of the fibre protruding from the holder and the peak was amplified when measuring a pressure wave travelling perpendicular to the hydrophone axis. This evidence points towards a bending mode which should be mitigated or at least accounted for in calibration procedures.
Overall, thiswork demonstrates the complexity of bubble dynamics and argues that the binary classification of stable and inertial cavitation is not an accurate representation. Given that bubble collapse shock waves dominate the cavitation emission spectrum, the detection of non-linear emissions within these spectra is by definition an inertial effect. To fully harness cavitation in clinical and industrial applications, further research is needed to identify and characterise the specific bubble dynamics that drive beneficial outcomes, particularly those that might not be distinguishable in the acoustic spectrum. Therefore future efforts should aim to develop more comprehensive diagnostic tools that integrate acoustic data with mechanistic understanding to improve safety and efficacy for more precise therapy
Mathematical modelling of active fluids in a channel
Get PDFActive fluids, such as active nematics, consist of self-driven units that convert energy into directed motion. Examples include suspensions of cytoskeletal filaments, motor proteins, bacteria, schools of fish, cellular layers, and cell tissues. This thesis presents a theoretical and computational study of active nematics using an adapted Ericksen-Leslie dynamical theory, with a focus on understanding how activity, external fields, and geometry influence flow and director patterns in confined systems. In one dimension, we investigate the effects of an orienting field on extensile and contractile nematics under planar and homeotropic anchoring. Extensile systems with planar anchoring exhibit minimal director distortion, whereas contractile systems display significant distortion when the orienting field exceeds a threshold from the initial homeotropic alignment. A kickback effect is observed in contractile nematics, which diminishes in extensile systems as activity increases. Nonlinear analyses reveal uniform, symmetric, and antisymmetric states, with activity enhancing flow and inducing bistability in contractile systems. In two-dimensional channels, we analyse the influence of activity and non-constant boundary conditions. Under inlet/outlet normal flow conditions, low activities produce localised flows, while higher activities generate spatial fluctuations in contractile systems. Extensile nematics at high activity exhibit transitions from unidirectional to bidirectional flow. For inlet/outlet periodic conditions, the system behaviour is similar to that under normal flow conditions. Variation in the splay-to-bend elastic constant ratio leads to transitions from positive to negative flux, demonstrating that active stresses can dominate elastic forces and produce unidirectional flow with positive flux for extensile systems. We also explore time-dependent boundary conditions as a conceptual demonstration of object sensing, showing that the speed of anchoring transitions affects flow patterns: slower transitions delay system activation, while faster transitions reduce bidirectional flows. These results indicate that small local disturbances can produce large-scale flows. In a biological context, such as wound healing, the tissue edge acts as a dynamic boundary where cells actively migrate and reorganise. Our findings on time-dependent boundary anchoring and activity-driven flows suggest that localised changes at wound margins can trigger large-scale tissue flows, mimicking the collective migration observed during wound closure. Overall, this work provides a theoretical framework for understanding how activity and confinement can be harnessed in systems that respond sensitively to local perturbations, highlighting potential applications for active-nematic-based sensing
Deciphering the origin and evolution of mantle plumes using the geochemistry of basalts from Afar and Iceland
No full textAbstract not currently available
Analog integrated circuit design empowered by artificial intelligence techniques: from building blocks to small systems
Get PDFAnalog integrated circuit (IC) design remains a major bottleneck in modern electronic systems due to its reliance on expertise-driven iteration and the growing complexity of performance, robustness, and variability requirements. This dissertation aims to advance artificial intelligence (AI)-driven analog IC design methodologies across three hierarchical levels: building blocks, subsystems, and systems.
At the block level, a design–insight–aware comparison is conducted across representative circuits including a StrongARM comparator, two Miller-compensated operational amplifiers, and an LC voltage-controlled oscillator (VCO) to benchmark AI-assisted optimization against conventional systematic flows. Post-layout and silicon measurement results demonstrate that AI-assisted frameworks can achieve superior performance and robustness while preserving design intent.
At the subsystem level, the first AI-driven co-design flow for VCO–LDO integration is introduced. By simultaneously optimizing both blocks under supply–noise coupling and frequency–pushing effects, the method improves phase noise, figure of merit (FoM), and runtime efficiency compared to sequential design, demonstrating the value of cross-block optimization.
At the system level, a global–local optimization framework with multi-fidelity simulation is proposed for asynchronous successive-approximation register analog-to-digital converter. This methodology cascades surrogate model-based global exploration with parallel pattern search refinement, achieving competitive FoM across 12 design cases (7–12 bit, up to 250 MHz) with significantly reduced runtime and minimal manual effort.
Together, these contributions establish a practical pathway for AI-driven analog IC design automation. By combining black-box optimization, learning-based acceleration, and designer in-the-loop validation, this work demonstrates measurable gains in design quality, robustness, and time efficiency, offering a foundation for future system-level EDA tools
Say their names: 'state talk' and resistance following deaths in custody in Britain
No full textAbstract not currently available
Synthesis, characterisation, and application of hexagonal triple perovskites as oxygen evolution reaction catalysts
No full textAbstract not currently available
Surveillance and Characterisation of the Humoral Immune Response to SARS-CoV-2 in UK Companion Animals during the COVID-19 Pandemic
Get PDFThe 2019 emergence of SARS-CoV-2, the causative agent of the COVID-19 pandemic, resulted in a global public health crisis. The virus is believed to have emerged from bats, via an intermediate animal species into the human population. This significant spillover has laid bare the significant gaps in the scientific community’s understanding of coronaviruses and the surveillance of viruses in animal species. Although SARS-CoV-2 can be considered primarily as a human pathogen, it has been shown to infect a diverse range of animal species, including white-tailed deer, mink and companion animals such as cats and dogs. These animal infections have resulted in severe pathologies in numerous cases, as well as rare instances of animal-to-human transmission.
In human diagnostics, reverse transcription polymerase chain reaction (RT-PCR) testing has been the gold standard for identifying active SARS-CoV-2 infections throughout the pandemic. RT-qPCR can also be used to identify SARS-CoV-2 animal infections. This thesis outlines a series of SARS-CoV-2 RT-qPCR-confirmed cases in domestic cats, demonstrating a range of clinical manifestations and outcomes. The occurrence of severe and sometimes fatal infections in both cats and dogs not only raises concerns for animal health, but also for public health, given the close contact between pets and humans and previously documented cases of SARS-CoV-2 zoonosis.
RT-qPCR’s utility in animals is limited by challenges in detecting asymptomatic or transient infections. As such, this thesis details the development of an enzyme-linked immunosorbent assay (ELISA) to be used alongside a pseudotype virus neutralisation assay (PVNA), to detect previous exposure to SARS-CoV-2 in companion animal populations. These assays were used in combination to test 5847 residual diagnostic feline samples, finding a neutralising antibody seroprevalence of 4.8%, alongside an ELISA seroprevalence of 13.7%. This large non-neutralising response is likely driven by the production of antibodies against viral epitopes that are not conducive to virus neutralisation, suggesting a complex humoral immune profile in cats following natural infection. Additionally, several demographic risk factors for SARS-CoV-2 seropositivity were identified in cats, including age and breed.
A companion serosurvey in dogs, comprising a smaller sample size, demonstrated a comparable overall seroprevalence (4.3% neutralising and 14.3% seropositive on ELISA) but notably lower antibody titres, indicating a weaker humoral immune response relative to cats. Analysis of immune responses in both species showed variant-dependent patterns of antibody neutralisation, which implied the existence of at least two distinct SARS-CoV-2 serotypes.
A small serosurvey was also conducted on pre-pandemic raccoon dog sera, uncovering evidence of antibodies against an unknown Betacoronavirus that were capable of cross-neutralising multiple SARS-CoV-2 variants. This finding provides insight into the potential role of raccoon dogs as hosts of coronaviruses with zoonotic potential and underscores the importance of expanded viral surveillance in wildlife.
The findings outlined in this thesis emphasise the importance of adopting a One Health approach to pandemic preparedness, integrating human, animal, and ecosystem health research to provide a comprehensive understanding of coronavirus transmission and evolution. The data presented also highlight the requirement for enhanced surveillance of coronavirus infections in companion animals, bats, raccoon dogs, and other wildlife to better characterise the Coronaviridae family and identify potential emerging threats. This knowledge is essential for the understanding of the origins of human coronaviruses like SARS-CoV-2, as well as for informing vaccine strategies, veterinary diagnostics and public health messaging
Cultural commodities in conflict. An analysis of moral panic in the discourse on antiquities trafficking in newspaper articles in Germany, 2003–2020
Get PDFThis thesis is an analysis of the public discourse about antiquities trafficking from Iraq and Syria in Germany between 2003 and 2020. Germany is a market country for illicit antiquities, with a long-standing market for antiquities from Western Asia. During the researched period, widespread archaeological looting in the wake of the then-current conflicts in Iraq and Syria became public knowledge through reports in news media. At the same time several important changes in the German media's treatment of the German antiquities market can be seen, especially with regards to antiquities from Iraq and Syria. Moreover, in this time, changes in the legislation regulating the antiquities market were adopted in Germany, at the time widely seen as a reaction to the discourse. The development of the public discourse on antiquities trafficking in Germany is analysed in this thesis using the sociological concept of moral panic. To this end, German-language newspaper articles are investigated in detail using news framing analysis. The trends and themes emerging from this media analysis are then contextualised with texts from the lawmaking process of legal changes in Germany in 2007 and 2016, and reactions from the antiquities market.
With this methodology, I show that the public discourse on antiquities trafficking rapidly spun into a moral panic between mid-2014 and early 2015, centering the alleged involvement of the terror group Islamic State (IS) in the illicit antiquities trade, and that the following legal change of 2016 was falsely presented to the public as a consequence of the narratives promoted in this moral panic. The thesis concludes with a discussion on the lasting impact of this discourse, the social and intellectual consequences of moral panics and misconceptions about antiquities trafficking, and what this can mean for the future of cultural heritage policies in market countries for antiquities
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