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Understanding the Role of Vehicle Emissions as Part of Urban Air Pollution Source Complexity
Get PDFAir pollution is a major global challenge, with urban areas disproportionately affected due to high population densities and elevated pollutant concentrations. Despite advances in vehicle technology and stringent emissions legislation, road transport remains a significant source of urban air pollution. This thesis explores road transport emissions using individual vehicle measurements made with fast-response techniques to improve understanding of the complex relationship between these emissions and urban air quality. Analysis of over 600,000 remote sensing measurements from across the United Kingdom (UK) revealed decade-long trends in vehicular emissions of carbon monoxide, hydrocarbons, ammonia (NH3), and nitrogen oxides (NOx = NO + NO2). The impact of national policies promoting diesel fuel use on air quality was evaluated, revealing that these policies led to an excess of 721 kt of NOx emissions in the UK. Rising NH3 emissions from an increasing number of gasoline and hybrid vehicles were also highlighted as a growing concern. Point sampling measurements demonstrated that vehicle exhaust location and aerodynamic properties influence near-road pollutant dispersion and concentrations, which suggests that targeting factors beyond direct emissions reduction could improve urban air quality. For example, relocating passenger car exhausts could reduce roadside pollutant concentrations by up to a third. Electric vehicles were found to disperse pollutants from fossil-fuelled vehicles, reducing near-road pollutant concentrations. Mobile monitoring in London, UK, showed that diesel and gasoline particulate filters effectively reduce particulate matter (PM) emissions, even under highly congested conditions. However, high-emitting vehicles and construction sites were identified as key sources of urban PM, indicating that non-vehicular sources are becoming increasingly important contributors to urban air pollution amidst a broader reduction in vehicle emissions
Optical and Radar Satellite Measurement of Volcanic Eruption Impacts on Vegetation
Get PDFVegetation disturbance caused by volcanic eruptions can span large areas and persist for years, yet remains poorly constrained and underutilised as a tool for understanding eruptive processes. Many volcanoes are located in forested and remote regions, where access is limited and field observations are difficult. In this thesis, I explore how optical and radar satellite remote sensing can be used to detect, quantify, and analyse vegetation disturbance and recovery caused by volcanic eruptions and emissions at volcanoes worldwide, encompassing a range of eruptive styles and environmental settings, to assess the global applicability of these methods.
This thesis is structured around three core investigations. First, in Chapter 2, I analyse vegetation disturbance and regrowth following the 2015 eruption of Calbuco, Chile, using Sentinel-2 NDVI time series and Sentinel-1 radar backscatter and coherence. I use this case study to test different methods and assess the most effective earth observation tools for studying vegetation disturbance at volcanoes. I demonstrate how declines in vegetation health and coverage correlate with deposit type, thickness and distribution, and show that forest recovery times vary with impact type and possibly local topography. These results are used to refine isopach maps and estimate eruption volume based on vegetation damage.
In Chapter 3, I assess the effects of volcanic gas emissions, particularly SO2, on forest health, using multi-year optical and radar observations at Krakatau, Semeru, Reykjanes Peninsula, Turrialba and Masaya. I show that both short-term eruptive plumes and long-term passive degassing cause measurable impacts to vegetation from satellite data, with spatial patterns and recovery trajectories linked to gas flux, exposure time, and vegetation type.
Finally, in Chapter 4, I present a global comparison of forest disturbance and recovery across 18 volcanoes, quantifying recovery times by disturbance type and forest biome. Tephra-affected areas recover most rapidly, while PDC and blast zones show much longer recovery times on the order of decades. Tropical forests recover faster than temperate ones, suggesting ecological resilience plays a major role. In general, the majority of impacted areas recover in as little as 30 years but flow deposits can significantly alter the vegetated landscape for hundreds to thousands of years.
Across all chapters, I highlight the value of optical and radar satellite data to monitor ecological impacts of eruptions, particularly when combined or used in conjunction with field campaigns. These methods offer new ways to assess eruption magnitude, map deposit extents, and evaluate ecosystem recovery, particularly in inaccessible regions. The findings also point toward broader applicability to other disturbance types, and show how vegetation change can be a useful proxy for understanding volcanic activity
Effects of urban vegetation on ambient PM2.5 concentrations in real urban environment
No full textAir pollution is a significant threat to public health, with over 90% of the global population exposed to fine particulate matter (PM2.5) exceeding WHO guidelines. The health and economic burdens of air pollution have drawn increasing attention from researchers, policymakers, and the public. Urban vegetation is often considered a potential strategy for mitigating air pollution. However, air quality is influenced by multiple factors in complex urban environments, including urban form, vegetation, and meteorological conditions, making it challenging to quantify the role of vegetation in real-world settings.
This research investigates the impact of vegetation on PM2.5 concentrations in urban areas, providing insights for urban planning and green infrastructure design. Using Harbin, Changchun, and Shenyang as case studies, this study develops a triple-stage research framework: (1) an ultra-high-resolution downscaling and calibration model for PM2.5 estimation, (2) an urban form cluster analysis categorizing urban areas into 13 types, and (3) an examination of vegetation’s influence on PM2.5 within these clusters. The study employs machine learning regression, clustering, deep learning-based image segmentation, and high-performance computing (HPC).
A novel multi-view urban vegetation index (MvUVI) is introduced to quantify spatial vegetation coverage. Results confirm that vegetation contributes to PM2.5 mitigation but with varying effectiveness across urban form clusters. We propose the Mitigation-Effectiveness Threshold hypothesis, suggesting that vegetation reduces PM2.5 only within certain external emission thresholds. When emissions from traffic or industry exceed these thresholds, the mitigation effect weakens or becomes ineffective.
The findings provide policy guidance not only for China but also for other rapidly urbanising regions worldwide, supporting the adoption of context-specific and evidence-based measures to improve air quality, particularly by highlighting the need to consider emission thresholds alongside urban greening strategies
Intra-crystalline amino acids in deep-sea corals: a first look at organic skeletal controls
Get PDFDeep-sea corals are found in oceans around the world. However, there are
emerging environmental challenges, like ocean acidification and climate change,
that could threaten deep-sea corals. Previous research into deep-sea corals and
how they respond to environmental change has been focused on biogeographic
habitat mapping and paleoclimate work, exploring their environmental history
using their skeletal remains. Most of this research has focused on inorganic
geochemistry – including dating and trace metal and isotopic compositions.
Despite the potential importance of biomineralisation in calcifying corals, there is
no existing information on the amino acid composition of deep-sea corals.
This study is the first analysis of amino acids in deep-sea corals, helping to fill
this knowledge gap. Using ultra-high-performance liquid chromatography
(UHPLC), intra-crystalline amino acids were extracted from two groups of deep-
sea corals - stylasterids and Scleractinia. One hundred and thirty-six deep-sea
corals were analysed from eight locations. First, the analytical and preparative
reproducibility were assessed. Then the internal heterogeneity was established,
showing that some coral tips have lower total hydrolysable amino acid
concentration (THAA) than branch sections. Overall, high levels of acidic amino
acids (such as aspartic acid and glutamic acid) support previous findings of coral
acid-rich proteins found within shallow water corals. Amino acid differences
were observed between stylasterid and scleractinian corals, with further
differences between aragonitic and calcitic stylasterid corals.
The new amino acid data was also compared to co-located hydrographic data,
(aragonite saturation, pH, dissolved inorganic carbon, temperature and salinity).
This comparison indicated that coral amino acids may be influenced by some
environmental conditions. Two clear correlations were found: (i) THAA increased
with decreasing pH within the scleractinian coral (Caryophyllia), and (ii), the
percentage of aspartic acid was higher in stylasterid corals living in water that
was undersaturated in aragonite compared to saturated conditions.
Together, these are the first THAA data from deep-sea corals and show variations
of amino acids between genera, mineralogies and correlations with
environmental parameters
Effect of porosity on the Tensile and Fatigue Behaviour of Inconel 738 Manufactured Through Laser Powder Bed Fusion
No full textThis work provides a comprehensive investigation of LPBF Inconel 738, a material fabricated using laser powder bed fusion technique and enhanced through a novel crack-healing post-processing technique. The research explores the microstructural characteristics and mechanical performance of this advanced material, comparing it systematically with conventionally cast Inconel 738. Employing advanced characterisation methods, multi-scale mechanical testing, and finite element modelling, the study examines tensile performance and fatigue behaviour under varying stress levels. Techniques such as Digital Image Correlation, Scanning Electron Microscopy, and X-ray Computed Tomography were utilised to analyse material behaviour and microstructural evolution.
The findings reveal that LPBF Inconel 738, enhanced through the Liquid-Induced Healing post- process, exhibits superior mechanical properties compared to cast alloys, including higher ultimate tensile strength and elongation to failure. Microstructural analysis highlights the refined, equiaxed grain structure of LPBF materials, contrasting with the larger, columnar grains of cast specimens. Lower porosity levels in LPBF materials (below 0.04%) contribute to their enhanced performance, as observed in slower crack propagation and greater fatigue resistance under cyclic loading. Primary cracking mechanisms for both materials have been proved to be intergranular fracture, where propagation occurs along the grain boundaries. LPBF specimens displayed superior fatigue life, though variability in performance was noted due to process-induced defects. Finite element modelling demonstrated the impact of porosity on fatigue behaviour, with larger and more irregularly shaped pores significantly increasing stress concentrations. The results emphasise that achieving low porosity levels and promoting refined, equiaxed grain structures are crucial for enhancing the fatigue resistance and overall mechanical performance of LPBF Inconel 738 material.
This study represents the first detailed exploration of the tensile and fatigue properties of LPBF Inconel 738, addressing critical gaps in the literature. The research establishes a foundation for adopting LPBF Inconel 738 in high-performance applications and identifies pathways for optimising additive manufacturing processes to enhance material durability and reliability
The good life? Focusing a capability lens on Zambia's social cash transfer programme
No full textThe social cash transfer programme is Zambia’s largest social protection programme designed to reduce poverty and curtail intergenerational poverty transfer through the provision of a bi-monthly cash transfer. To do this, the unconditional cash transfer programme has five key objectives: supplement household income, contribute towards an increase in the number of children enrolled and attending primary school education, reduce mortality and morbidity among children under five years, increase households having a second meal daily and promote household food security and increase in the number of households owning assets such as livestock.
Using a capability lens, this thesis examines the bridge, or lack of, between the programme’s expectations and the lived realities of the recipients. It does this by investigating the values and rationalities of policymakers and recipients as manifest in their conceptions of well-being or poverty and its reduction. These conceptions are viewed in the capabilities highlighted in the objectives of the program on one end and the recipients’ capabilities viewed in the various things they manage to do with social cash transfers on the other end. In so doing, this research identifies how different policy actors perceive well-being and poverty reduction, viewed and understood through what they value and have reason to value: their ideas of the good life. Through the implementation process, the research then examines the interaction of some design and implementation features and their influence on the conversion of social cash transfers into capabilities (opportunities) and the choice of functionings (achievements).
This ethnographically inspired qualitative study uses interviews with social cash transfer policymakers at the Ministry of Community Development and Social Services Headquarters, including the Programme Implementation Unit (PIU), implementers at the district and community levels, as well as recipients of social cash transfers in two districts of Zambia. It also uses secondary data from policy guidelines, briefs and reports from the implementing organisation.
The study finds that the conception of poverty and its reduction and well-being by policymakers and social cash transfer programme recipients differ because of their diverse values and rationalities. Policymakers define poverty as incapacitation and vulnerability and operationalise its reduction and well-being into the five objectives, which focus on material well-being. The objectives are not consistent with the principles of the capability approach relating to being holistic or multi-dimensional. For social cash transfer recipients, poverty is defined in material, relational and subjective terms as portrayed in the diverse dimensions viewed in their use of cash transfers, therein their ideas of the good life. Therefore, there is a disconnect between the expectations of the programme and the lived realities of the recipients, which the implementation process attempts to balance.
The thesis finds that some features in the design and implementation of the program are not consistent with the capability approach because they exhibit forms of conditioning that do not recognise aspects of the capability approach. The design’s non-consideration of agency and freedom, including conversion factors, renders it paternalistic. Owing to the disconnect, the thesis proposes a capability-based social cash transfer programme that is holistic, human-centred, multi-dimensional and recognises factors in the social structure that affect the expansion of capabilities and the achievement of functionings.
This thesis has theoretical and practical relevance. It offers avenues for improvement in the design and implementation of social cash transfer programmes by increasing the information base in determining how well people are doing. It also contributes to the literature on the capability approach by considering how resources are converted into capabilities and functionings, and the freedom people have to determine their course of action. Therefore, it highlights the influence of some design features on the utilisation of social cash transfers. The research further contributes to scholarship on cash transfers and the capability approach by highlighting what different people value and have reason to value (ideas of the good life)
Modelling plasma cell differentiation to risk stratify secondary antibody deficiencies for immunoglobulin replacement therapy
Get PDFB-cells of patients with secondary and primary antibody deficiency often exhibit
defects in maturation, activation, or survival, which may lead to impaired immune
responses after SARS-CoV-2 vaccination. These defects contribute to vaccine non-
responsiveness in some patients. The underlying mechanisms and the feasibility of
pre-vaccination risk stratification remain unclear. To investigate B-cell intrinsic
differentiation capacities in a heterogeneous cohort of vaccine-responding and non-
responding antibody-deficient patients, an in vitro plasma cell differentiation model
has been utilised. Such an approach may also be useful in assessing their suitability
for immunoglobulin replacement therapy (IgRT).
B-cells from participants enrolled in the COV-AD study, taken after their fourth
SARS-CoV-2 vaccine dose, were isolated and induced to differentiate into plasma
cells. B-cell functionality at critical differentiation stages was assessed using flow
cytometry, ELISA, BCR analysis, and RNA sequencing. The study revealed distinct
differences in B-cell differentiation between vaccine responders and non-responders.
Non-responders (n=15) and a subset of responders (n=10/35) exhibited significantly
reduced or absent expression of the BAFF-R survival receptor. Immunoglobulin
heavy chain sequencing showed no significant differences in BCR profiles between
responders and non-responders. Both patient groups displayed reduced intracellular
and secreted IgG and IgA expression compared to healthy controls.
Atypical B-cell differentiation profiles in antibody deficient patients, particularly
reduced BAFF-R expression, may underpin impaired SARS-CoV-2 vaccine
responses. The identification of BAFF-R as a critical survival receptor emphasises its
potential as a biomarker for risk stratification. Integrating BAFF-R profiling into
clinical workflows could help identify patients at risk of poor immune outcomes,
enabling tailored therapeutic interventions. Refining this in vitro plasma cell
differentiation model to allow for faster assessments, focusing on BAFF-R levels and
other key markers, will enhance its feasibility as a practical tool for pre-IgRT risk
stratification in clinical settings
Investigating the Multimodal Meaning-Making of Wordplay in Arabic-Subtitled TV Series: An Audience Reception Study
No full textThis thesis investigates how Arabic subtitled humorous wordplay in the sitcom One Day at a Time is received and perceived by Saudi viewers. It investigates the effect of different translation strategies, language proficiency and the presence or absence of canned laughter and wordplay explicating gestures. In addition, it explores the interplay of these variables and how they influence reception and perception. While a large body of research has examined wordplay in both descriptive and theoretical approaches, research on the reception and perception of Arabic subtitled wordplay remains limited. Therefore, this thesis aims to fill this gap by providing findings from its reception and perception study to enhance the understanding of wordplay in audiovisual translation (AVT) practices in general, and more specifically in the context of Arabic subtitled audiovisual material. The reception study investigates the impact of different strategies (neutralisation and compensation) on viewers’ comprehension of wordplay, while the perception study explores their perceived levels of understanding and enjoyment. This thesis also seeks to contribute to the growing AVT practices in Saudi Arabia in light of Vision 2030, which gives particular attention to the entertainment and media industry
How practitioners make sense of expressive story writing and how that can be experienced as therapeutic
Get PDFThis research explores expressive story writing and how that can be experienced as therapeutic. Therapeutic Story Writing Groups (TSWGs) are an expressive story writing intervention that can be used in Educational Psychology (EP) practice and were being delivered in the local authority (LA) I worked in. Previous research into TSWG has used quantitative methodologies and their associated paradigm(s) and none explored the experiences of either facilitators or CYP in qualitative depth. I was interested in how practitioners view the ways TSWGs could support creativity and self-expression in Key Stage 2 students. From a contextualist epistemology and critical realist ontology, reflexive thematic analysis was used to analyse participant interview transcripts, allowing their truths to be validated whilst acknowledging existing structures and instances of power within schools and LA services. Key messages from analysis were: that TSWGs provide something different for children to their usual school experience; that facilitators are not exempt from systemic pressures; that practitioners adapted the intervention’s structure and delivery; that children are given opportunities to make social connections and voice worries; that most children could express themselves comfortably through a process of exploration and externalisation; that the group felt like a relational space, which promoted equalizing and connectedness; that practitioners valued the intervention for building children’s emotional literacy; that practitioners felt children’s confidence generally increased during the sessions; and that there was a sense of transformation taking place in children. Building children’s emotional literacy and providing a sense of transformation in a six-week period demonstrates the potential impact of this relatively low-cost therapeutic and expressive story writing intervention. The benefits of TSWGs reported here indicate that TSWGs could be usefully adopted within LAs to support children, particularly those in Key Stage 2. EPs in most LAs are well placed to train and supervise practitioners in delivering such groups
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