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Decarbonisation cost optimisation for Diesel Railway traction system conversion
Get PDFIn the field of transportation, especially with trains, lowering carbon emissions is a very important problem. This thesis introduces a novel approach centred on cost optimisation for converting from diesel-powered trains to more environmentally sustainable alternatives. It combines different new green power technologies like electrification, hydrogen fuel cells, and batteries, with the goal to reduce carbon emissions and also keeping in mind the cost. A significant aspect of this research involves the development of a multi-mode train simulator. This innovation in railway technology enables accurate calculations of energy consumption and efficient management of various power systems in different operational scenarios. Its capability to handle train operation strategies is important, enabling more accurate assessments of the cost-effectiveness in decarbonisation strategies.
The study includes a detailed economic analysis over a period of 40 years. This analysis focuses mainly on the costs involved, including replacing diesel parts, installing new power systems, and their maintenance over a long time. This deep cost analysis gives important understanding about the money aspects of changing to green power in trains. Also, the research uses advanced methods like the Genetic Algorithm and Particle Swarm Optimisation to accurately change important things such as how long the electrification should be and how powerful the energy systems need to be. These methods are used to find the best ways to save costs, showing a new way of looking at costs in making railways more eco-friendly.
The results of the study about saving money are obvious. The research shows that using trains with different modes could make the costs go down by 40.4% compared to normal diesel trains, as seen in the example of the train route from London St. Pancras to Leicester. This shows the financial good points of using different kinds of green power in trains. The study also looks at how trains powered by hydrogen might be used in the future. Right now, they are not as cost-saving as other choices, but the study says they might become better as the price of hydrogen goes down. This part of the research shows how new green power can change the way we think about making trains more eco-friendly in the future, especially about the costs.
In summary, this study is very important for making trains more eco-friendly, focusing a lot on saving costs. By bringing together new technologies and ways of doing things, it deals with environmental problems while also thinking a lot about how much things cost. The ideas and ways used in this study are very useful for making future plans and policies in trains, leading to a future that is both more sustainable and saves money
A functional screen of novel haematopoietic players in haematopoietic ontogeny
Get PDFAll blood cells in the adult differentiate from a common precursor, the haematopoietic stem and progenitor cell (HSPC), which arise from the haemogenic endothelium (HE) in the dorsal aorta, migrate to an intermediary haematopoietic organ (CHT in zebrafish) to proliferate late seed the definitive haematopoietic organs. Many genetic and epigenetic mechanisms regulate these processes; however many questions remain unanswered regarding the exact mechanisms of this regulation. By analysing recently published data from haematopoietic tissues including the HE and emerging HSPCs, this thesis aimed to identify novel players in HSPC ontogeny, and functionally analyse them. Seven candidate genes were selected, and functionally analysed using CRISPR-cas9. Loss of sart3, wasla, ptpn13, tead1a, esrp1, etv5b, and spi2 all resulted in impaired haematopoietic development. Performing differential gene expression analysis, genes upregulated in the HE were identified, and their functional co-expression network constructed. This revealed a further two genes which are co-expressed together with spi2 – thy1 and ncf1. Upon knockout both genes showed haematopoietic phenotypes in terms of HSPC and lineage marker expression. Further analysis is needed to characterise the function of these candidate genes, however we conclude that our approach is effective at identifying novel players in haematopoiesis
Rising when we fall: understanding resilience in orangutans and other great apes
Get PDFGreat apes in rehabilitation centres and other captive environments must have the capacity to overcome adversity. Research in humans and other animals has shown that psychological resilience can help individuals ‘bounce back’ from stress. However, there is limited existing knowledge about how resilience might underpin the survival of great apes released back into the wild, or their wellbeing in long-term captivity. The first step towards understanding the importance of resilience in these contexts is identifying techniques to measure and increase resilience in great apes. This thesis lays the groundwork for a new field of research by evaluating appropriate and effective resilience interventions for captive great apes, exploring how species and individual differences may affect stress and resilience. This research involved conducting a scoping review of resilience interventions in humans and other animals, identifying several interventions with potential applicability to great apes (Chapter 2). Building on these results, a novel resilience intervention was trialled in captive orangutans and gorillas, showing promising results in terms of the potential of this intervention to increase persistence and skill in tool-using (Chapter 3). An investigation was also conducted into the effects of a potential major stressor, i.e. the effects of a period of zoo closures in England, due to the Covid19 pandemic (2021), on orangutans and gorillas, identifying several species-specific effects and complex visitor effects (Chapter 4). Lastly, the implications of individual variation on welfare and resilience were explored in a case study of a neurologically and physically divergent orangutan, which highlighted several welfare implications as well as challenges in individually tailoring resilience interventions (Chapter 5). This thesis lays the foundation for future research
into great ape resilience, contributing to wider efforts to return great apes to the wild and, where this is not possible, to maximise the wellbeing of great apes in long-term captivity
A qualitative inquiry into primary student teachers’ construction of knowledge regarding teaching children learning English as an additional language
Get PDFIn England, government policy for the education of children learning English as an Additional Language (EAL) is under-specified in the policy contexts of primary education and Initial Teacher Education (ITE). The system of teacher education is highly regulated by the Department of Education and Ofsted where student teachers are taught ideologically informed content during ITE. Student teachers spend the majority of their teacher education time in schools, privileging learning from practice defined by the local contexts of the practicum experience. The under-specification of EAL contributes to variability in EAL expertise and practice in schools and hence, student teachers’ experiences of practice-based learning.
This small-scale study explores postgraduate student teachers’ construction of knowledge for teaching children learning EAL for teaching in mainstream primary classrooms in England. In order to examine student teachers’ navigation of their experiences, a bespoke theoretical framework was created to ensure a balance between trustworthiness and credibility while investigating the experiences contributing to student teachers’ construction of knowledge. The theoretical framework sets out a rationale for the qualitative exploration of student teachers’ cognition and, the influence of the relevant macro and micro contexts of their experience on their construction of knowledge of EAL pedagogy before and during ITE. The research design sits within an interpretivist paradigm and is structured using a Life History Research design frame. Purposive sampling was employed in the recruitment of six participants based on their interest in EAL pedagogy as part of ITE.
Data gathering was conducted at the beginning of the participants’ PGCE programme (Phase 1) and towards the end of the programme (Phase 2) using questionnaires, reflective journals and semi-structured life history interviews. Data were analysed using thematic coding analysis and narrative analysis. Findings are presented in the form of life histories for three of the participating student teachers. Cross analysis of participants’ data presents a holistic view of the data providing intersubjective themes that recover pedagogic discourses operating at macro levels of context from the participants’ micro level experiences before and during ITE.
Analysis of the data employs an ecological view of student teachers’ agency in the construction of knowledge of EAL pedagogy. Discussion refers to the presence and influence of powerful, ideologically informed, tightly regulated pedagogic discourses in shaping student teachers’ teacher education experiences and hence, construction of knowledge of EAL pedagogy. The possibilities for constructing knowledge of EAL pedagogy, aligned to the professional knowledge base, in the middle ground of ITE are analysed citing the challenges and obstacles face by teacher educators and student teachers in the macro and micro contexts of ITE.
The study concludes with recommendations for teacher educators’ practice including developing their own and their student teachers’ capacity to engage in reflection on EAL pedagogy while attending to linguistically responsive teaching practices
Complex spatial structures in biomedical images: investigating the interaction of cells with their microenvironment
Get PDFImaging modalities can resolve biological systems with a precision that can spatially locate individual cells of multiple cell phenotypes. Identifying meaningful patterns in heterogeneous, multi-agent and high-dimensional images grows in importance as high-throughput versions of this technology develop. Mathematical constructs offer simplifications which are then able to interpret a myriad of complex spatial structures, including point patterns, spatial complex networks and homological features. These constructs provide quantification which enables predictive power for patient disease progression and to infer optimal biological function.
Before the characterisation of images into mathematical representations, ascertaining a reliable signal amidst noise is a foundational step in describing the features of images accurately. Recent developments in machine learning have provided a powerful set of techniques for the automated analysis of complex structures in images. Leveraging these, we integrate the use of advanced image processing techniques, combining tools to construct effective processing workflows. For instance, in the identification of cell boundaries and their respective phenotypes from 2-dimensional multiplex immunofluorescence images or blood vessel structures from 3-dimensional confocal fluorescence microscopy.
Spatial analyses then encapsulate pairwise interactions, multi-phenotypic neighbourhoods and structured cellular neighbourhoods, a novel concept introduced in this research. In this thesis, we apply our techniques to 2-dimensional and 3-dimensional imaging modalities investigating features in three biological systems: Colorectal carcinoma, Sjogren's syndrome and self-organised microvascular models.
In colorectal carcinoma, we identify several immune cell phenotypes of interest for patient prognosis, such as M2 macrophages with cancerous epithelial cells. In Sjogren's syndrome we automatically identify tertiary lymphoid structures, otherwise known as ectopic lymphoid organs, a prognostic predictor of patient progression in this disease as well as in many cancers. Finally, the characterisation of self-organised microvascular models as complex spatial networks improved the classification of samples according to the medium environment and related subsequent morphology to analytical simulations of oxygen and nutrient flow
Accuracy of statistical models for crime linkage and the exploration of sexual offence classes
Get PDFChapter one of this thesis is a meta-analysis of the accuracy of statistical models used to link crimes, as measured by the Area Under the Curve statistic. This chapter includes the process used to gather, and extract relevant papers and data, the model selection, and findings of a three factor random effects model. In the empirical research paper (chapter two), subgroups of offence behaviours, offender traits, and demographic characteristics are identified in sexual offences. This research is based on the Swiss ViCLAS database and uses latent class analyses to identify subgroups of different variable sets. Associations between the three sets of subgroups are also evaluated using log-linear analysis. Finally, chapter three and four present press release documents of chapter one and two respectively. These chapters are written for the purpose of public dissemination. They both include brief overviews of the aims, findings, and conclusions from the meta-analysis and empirical research chapters
Dielectric leaky wave antennas for future terahertz systems
Get PDFThis thesis endeavours to enhance the performance of terahertz antennas for communication and sensing applications. In pursuit of this objective, the thesis presents the design of two integrated dielectric leaky wave antennas (LWAs) operating in the sub-terahertz band. It includes the design of a H-band Dirac leaky wave antenna (DLWA) constructed from micromachined silicon, which is suitable for beam scanning applications. Additionally, the research encompasses a H-band direct laser written polymer Fabry-Perot cavity antenna (FPCA), designed for stable beam pointing applications.
In this thesis, the proposed DLWA represents the first instance of a sub-terahertz band all-dielectric DLWA featuring a closed bandgap. The all-dielectric unit cell exploits accidental degeneracy (i.e. frequency-balancing) to achieve suppression of the open stopband at broadside radiation. Through dispersion analysis of the unit cell, the radiation aperture is tapered with a Taylor amplitude distribution to achieve a sidelobe level (SLL) less than -30 dB at the center frequency while keeps the open stopband suppressed. The DLWA proposed in this thesis exhibits a fan-beam radiation pattern, low sidelobe levels (SLLs), and high aperture efficiency across the entire WR-3 frequency band. To mitigate Ohmic losses and enhance total efficiency, the antenna was fabricated using through-hole deep reactive ion etching (DRIE) on a high resistivity silicon wafer. The fabricated prototype of the DLWA has been measured, providing further validation for the proposed design.
Additionally, for the first time, an all-dielectric direct laser written FPCA operating at WR-3 band is proposed. Leaky wave analysis and transvers resonance method is used for the unit cell design. For a wider working bandwidth, the resonance unit cell of the FPCA’s partial reflective dielectric surface is tapered. Additionally, the total quality factor of the FPCA's resonance cavity is carefully adjusted to optimize gain while minimizing dielectric losses attributed to the photoresin. A standard UG-387/U flange shim is fabricated to integrate the FPCA with open-ended waveguide and evaluate the performance of the FPCA. After the measurement of the fabricated prototype of the FPCA, it was confirmed that the innovative design eliminates the need for additional iris and matching metal layers. This achievement leads to good impedance matching and a high 3 dB gain bandwidth product (GBWP), surpassing the performance of similar antennas reported in previous publications.
Finally, this thesis discusses the remaining issues and future work plans for the two antenna designs proposed
Comparative genomic analysis of and diversity: assessing the impacts of travel, animal husbandry practices and lifestyle
Get PDFAntimicrobial resistance is a significant public health problem which is further exacerbated by the increasing prevalence of resistant pathogens, particularly of bacterial origin, which cannot be effectively treated with existing antimicrobials. In East Africa this is a critical problem due to limited resources available to combat it. Currently there is very limited whole-genome sequencing (WGS) data addressing antimicrobial resistance genes (AMR) patterns and the underlying mechanisms of transfer of resistance genes. In the present study we employ WGS to shed light on the complex dynamics of AMR in Gram-negative opportunistic pathogens ( and ) in East Africa. Here, AMR patterns were investigated before and after travel, in the context of animal husbandry, as well as in distinct communities with varying lifestyles. Consequently, this study provides insights into the AMR patterns in these three situations at genomic level while also contributing to the relatively scarce WGS data existing literature in East Africa.
Short-term colonisation of different species were observed pre- and post-travel, which lead us to suggest that travel may have an impact on composition of gut microbiota. Moreover, acquisition of AMR was mostly seen in multidrug-resistant (MDR) strains both pre- and post-travel. Resistance genes in these strains were mainly associated with plasmids, giving weight to the important role of mobile genetic elements in the spread of AMR. Our study did not find evidence for widespread acquisition of ESBL-producing strains but found that colonization by MDR strains was common. Furthermore, the majority of strains were closely related, suggesting a common source and/or transmission between individuals in the study population.
In a second study, significant proportion of strains from livestock exhibiting resistance to antimicrobials were observed, that were commonly employed in animal husbandry. Further analysis of the data revealed a higher prevalence of MDR in poultry compared to pigs. This was attributed to varying antibiotic use between the two animal husbandry systems and context-specific variation in diseases prevalence. Upon further exploration of the data, sharing of strains between animal groups were seen, revealing evidence of different AMR reservoirs being shared between poultry and pigs. These findings emphasise the importance of adopting a One Health approach that considers the well-being of different animal groups, humans, and the environment.
Further to this, MAGs from previously published studies were reconstructed to conduct a comparative study so that we can understand the difference in gut diversity between the Hadza and the general population in Tanzania. Three MAGs were successfully reconstructed following metagenomic analysis of the sequences. No evidence of resistance was found and virulence genes in the identified MAGs. However, this may have been attributed to quality of the data. Further observation of the data revealed variation in genes linked aromatic amino acid metabolism between MAGs derived from the two communities, notably the absence of , and genes in the Hadza.
In summary, our study emphasizes the importance of considering local conditions in AMR research. Additionally, it sheds light on the transmission of resistant bacteria between different animal species, as well as the identification of genetic elements that contribute to the spread of AMR. Our findings underscore the importance of monitoring and targeted interventions that are adapted to environments. Moreover, our study supports the adoption of a One Health approach that integrates local practices, animal care and human behaviour to combat the growing problem of AMR, in Sub Saharan Africa
Predictors of health-related quality of life after lung cancer surgery
Get PDFGlobally, lung cancer is the leading cause of death. Surgical removal of a primary non-small cell lung cancer (NSCLC) tumour offers a significant chance of cure for those suffering. Additionally, it is anticipated that the introduction of screening programs for lung cancer will result in an increase in survival rates. Therefore, health-related quality of life (HRQOL) following surgery has become an important consideration for these patients. However, a considerable number of lung cancer patients who have undergone surgery have not experienced improvement in their breathing afterwards, a condition that can persist for several months following surgery. Computed Tomography (CT) scans of lung cancer patients often demonstrate concurrent emphysema with low attenuation areas (LAAs), the significance of which is unclear. Moreover, sarcopenia is observed in about half of lung cancer patients and is linked to impaired health outcomes and lower survival rates. Identifying the predictors of postoperative HRQOL declin
Assessment of the risk of post-operative pulmonary complications and mortality using analytic morphometry in patients undergoing major non-cardiac surgery
Get PDFSome 20% of patients undergoing major abdominal surgery develop post-operative pulmonary complications (PPC). This is a nebulous group of respiratory pathologies that occur frequently after major abdominal surgery, significantly impacting functional recovery and survival.
Effective preoperative risk stratification and prevention are crucial for optimal clinical outcomes. Thorough pre-operative assessments usually include full-body imaging. However, the valuable information obtained is not fully utilised. This untapped quantitative data provides an opportunity to identify new biomarkers (radiomarkers, morphomarkers) associated with PPC and survival, enhancing preoperative risk assessment understanding and improving patient care.
Two cohorts of patients were retrospectively analysed in this thesis: a cohort of patients with aortic pathology and a cohort of patients with colorectal cancer. The morphometric body composition parameters were analysed prospectively using Terarecon software.
I established the incidence of PPC which were higher than reported in the literature for the vascular cohort (24.2%) and within expected range for the colorectal patients (9.2%). I also established factors associated with PPC and their relation to mid-term survival. The presence of peripheral arterial occlusive disease (PAOD) and aneurysm diameter in vascular patients, as well as pre-existing chronic lung conditions (CLD), lymph node involvement at level N1 and N2, dementia, atrial fibrillation (AF), white cell count (WCC), male gender in colorectal cancer patients, are the most important independent risk factors for the development of PPC. It was established that PPC development was independently associated with survival in colorectal cancer patients.
I investigated the associations between quantitative computed tomography (CT)-derived structural lung morphology with PPC and survival. This resulted in the identification of potential new morphomarkers that could be useful in preoperative stratification of the patient’s risk. Lung tissue volumes measured at certain Hounsfield Units (HU) thresholds (high, normal, and low attenuation areas measured at HAA(VOL) -850 to -500 HU, NAA(VOL) -850 to -750 HU, and LAA(VOL) -950 HU) and airway volume were associated with PPC development and survival following vascular and colorectal cancer surgery, respectively.
Evaluation of indices of body composition including psoas, diaphragm muscles, and abdominal adipose tissue identified diaphragm thickness as an important morphomarker that may be useful in identifying patients at risk of developing PPC. I also analysed these in the context of survival, demonstrating a significant association between diaphragm thickness and total psoas muscle area (TPA) and survival in colorectal cancer patients.
The inclusion of lung morphology and body composition morphomarkers to clinical regression models alongside clinical patient-related factors improved their overall performance and predictive ability for PPC and survival.
Lung morphology and body composition morphomarkers can form a useful, otherwise not used, set of factors that should be used in preoperative assessment. Further work is warranted to build predictive, rather than exploratory models using morphomarkers described in this thesis. Machine learning models could be useful in not only facilitating this, but also helping in developing new lung analysis techniques.
Defined PPC by the European Joint Task-Force for Perioperative Clinical Outcomes (EPCO), are a heterogenous group of complications with different aetiology. It is therefore unsurprising that despite their important association with mortality, the relation with lung structure and composition is not uniform. Further research is required to determine usefulness of assessment of lung morphometry and body composition in stratification of perioperative risk in patients after non-thoracic, non-cardiac procedures
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