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Exploring applications of liquid metals in robotic systems
Full text linkCurrent robotic systems are typically made using all rigid materials. This causes them to have precise, fast control. However, all-rigid robots face difficulty handling delicate objects and interacting with people, who may get injured by them. Additionally, if the robot gets unexpectedly caught on an obstruction, it can get stuck and damage its motors. The introduction of controllable soft elements using low melting point alloys can eliminate these problems. For example, the phase change of liquid metal (between liquid and solid) can provide an extreme change in stiffness to help a robot pass by an obstruction. For grasping delicate objects and interacting with people, soft robots can be used instead of rigid. Typically, soft robots utilise a pump to change the pressure in a liquid, or high voltage to compress a fluid enclosed within a shell. However, the use of external pumps and high voltages limits their usefulness. Using liquid metal as the fluid, it is possible to create soft robots actuated using low voltages without using external pumps. This thesis therefore aims to solve problems in robotics using the unique properties of liquid metals.
Firstly, a smart stiffness changing elastomer made using a non-toxic low melting point alloy − Field’s metal (melting point 62 °C) − is created. This elastomer composite exhibits unconventional and tuneable mechanical and electrical properties that change with temperature and strain. Its resistance decreases by orders of magnitude when compressed or stretched. The electrical and mechanical properties are first investigated with variations in applied stress and temperature. Afterwards, its smart ability to change stiffness and resistance upon a combination of mechanical and electrical stimuli is demonstrated. It is then used in two proof of concept demonstrations − to make a variable stiffness compliance module for robotic grippers, and a resettable fuse.
Secondly, a capillary liquid metal muscle is created, which utilises the giant, switchable change in interfacial tension of eutectic gallium indium liquid metal to generate force and movement. The theory behind the working of the muscle is first explored, and the estimated force output for capillary size and overall diameter is calculated. The design is then optimised for maximum force and stroke. Tests were done on force change for various frequencies, movement of the muscle for different mass payloads, and the effect of different electrolytes on the performance of the muscle. The force output of the muscle and its position during movement is able to be controlled using feedback control. Finally, designs with extra small capillary slit widths are fabricated and tested, showing further increased force change.
Overall, this thesis explores two different ways that liquid metals can be used to improve robotic systems
Fifteen-year survival of root canal treated teeth in England and Wales
Full text linkObjective
Investigate the fifteen-year survival curve for root treated teeth in adult patients treated within the National Health Service General Dental Services (NHS GDS) in England and Wales by General Dental Practitioners (GDPs).
Methods
The data source was the age-stratified random sample of NHS GDS patients and the treatments they received over the period from 1990 to 2006 (SN7024 from https://ukdataservice.ac.uk). The survival was measured to reintervention which was categorised as re-root canal treatment, root-end surgery (apicectomy) or extraction after root canal treatment (RCT). Analysis was carried out using modified Kaplan- Meier methodology to establish survival curves extending to fifteen years and investigation of factors that can affect survival.
Results
The 15 years survival of root canal treated teeth by GDPs was 77% based on reintervention for 791,375 RCT teeth from over 2.5 million patients, whilst based on extraction the 15-year survival was 83%. The investigation of factors that affect survival were carried out and indicated that there were some dentist, patient and tooth factors of significance. The dentists in their 30s had the best survival outcome whilst the opposite was evident for dentists aged 60 and above, also dentists working in South Central England had markedly better results than those in Wales. The age of the patient and the full charge paying status of the patient were also significant factors.
The tooth factors investigated revealed better survival among posterior teeth, lower teeth, and those restored after RCT with a crown, bridge abutment and pin/screw. A previous history of RCT, post, crown and bridge abutment decreased the survival of the RCT teeth. Occlusal restorations also decreased the survival both before and after RCT.
Conclusion
The 15 years survival of root canal treated teeth carried out on 791,375 teeth by GDPs in England and Wales was 77% based on reintervention and 83% based on extraction. These findings are encouraging and appear to support the provision of RCT by GDPs working in the NHS GDS to save teeth. Two dentist factors, two patient factors plus tooth factors including the tooth position and nine types of restorations were found to be significant
One researcher’s noise is another’s data: using radio astronomy observations to study small-scale structures in the Earth’s ionosphere
Full text linkThe LOw Frequency ARray (LOFAR) provides a unique opportunity to observe the mid-latitude ionosphere. Although it is intended for astronomical observation, the signals from astronomical radio sources are distorted as they pass through the ionosphere. The nature of these variations in intensity and phase can provide detailed information on structures in the ionosphere at a range of scales, and the distributed network of LOFAR stations provides opportunities to characterise the propagation, spatial extent and temporal evolution of these structures. Because of the frequencies observed, wide bandwidth, spatially distributed network and high sensitivity provided by LOFAR, the observations of ionospheric phenomena made using LOFAR are highly complementary to other established techniques for observing the ionosphere.
Using just intensity measurements, it is shown that LOFAR can detect structures on spatial scales which are inaccessible with many other common techniques. A case study is presented in which LOFAR broadband intensity measurements from a bright cosmic radio source are used to infer the presence of a travelling ionospheric disturbance with a wavelength of 20 km. This is achieved by comparing the observed intensity as a function of frequency and time to the modelled intensity, considering the ionosphere as a 1-dimensional thin screen containing a sinusoidal perturbation. Extensions to the model are also used to identify deviations from a simple sine wave shape. Other data sources such as Global Navigation Satellite System (GNSS) Total Electron Content (TEC) and ionosonde measurements are used to confirm that the model parameters used are physically reasonable.
The calibration process for interferometric observations provides another means of studying the ionosphere with LOFAR, as it produces a direct measure of TEC. This is sensitive to disturbances up to an order of magnitude smaller than those detected using GNSS signals. A method is presented for identifying waves in this data and calculating their wavelengths, amplitudes and propagation directions, including robust characterisation of the uncertainties in these parameters. The range of wave parameters which can be identified in this way is shown to be complementary to previous work using networks of GNSS receivers, extending to lower amplitudes and shorter timescales. Using this analysis method with 2,700 hours of observations, the statistics of ionospheric waves observed using LOFAR are investigated, showing a dominant population with directions tracking the neutral wind, which are associated with atmospheric gravity waves (AGWs). The precise relationship between wave direction and wind direction is found to be period dependent, indicating a previously unreported feature of AGW propagation in the thermosphere. A secondary population of field-aligned plasmaspheric disturbances is also found to be present in the observations.
Within the regular ionospheric scintillation observations made with LOFAR, a class of scintillation features referred to here as `U-shaped scintillation' are identified. These are shown to occur on northward lines of sight at low elevation. They show an increased occurrence rate at night during winter relative to other seasons and times, and an elevated occurrence rate during geomagnetically active conditions. Detailed investigation of one of these events indicates that the structures responsible are strongly field-aligned and likely occur within the auroral oval or the poleward wall of the mid-latitude trough. Possible explanations are proposed for the frequency dependent behaviour of this scintillation
An investigation into the construction of secondary geography teacher identity
Full text linkOver the past thirty years there has been increasing interest in teacher identity. Although there is no clear consensus of a definition of teacher identity, theoretical understanding has remained consistent for the past two decades. It is widely accepted that teacher identity is complex, multifaceted and dynamic, and is influenced by a range of factors, including:
• personal narratives and biographies;
• social and organisational contexts; and
• disciplinary and pedagogical knowledge.
This thesis investigated the construction of secondary geography teacher identity. There has previously been limited research focusing on geography along with other non-core curriculum subjects. This research aimed to contribute to the current knowledge gap by specifically drawing on the experiences of current and previous secondary geography teachers, who had taught in England, to contribute to the understanding of secondary geography teacher identity.
The two phases of data collection took place between October 2020 and March 2022 against a backdrop of educational reform and a global pandemic. During this time, there were national and local lockdowns due to the Covid-19 pandemic. As a result, data collection took place remotely. Two hundred and thirty-seven secondary geography teachers contributed to the online survey, and fourteen of these participants undertook an interview. Participants ranged from those who were Early Career Teachers, to those with over forty years’ experience of teaching.
Through the collection of their narratives, the research provides insights into participants’
experience of:
• their geography education;
• their teacher education;
• their career; and.
• potentially why they have left the profession
The findings provide insight into participants’ geography journey, why they decided to become geography teachers, why some have remained geography teachers and why others may decide to stop teaching geography and/or leave the profession entirely.
It is evident from this research that the development of a teacher’s identity is not linear, as it shifts in time and context. In the literature, these shifts are an acknowledged part of becoming a teacher. The call for more rigorous exploration of identity is to ensure that teachers can address tensions and conflicts when they arise. If teachers are given the skills to address these tensions, it can be extremely valuable in creating greater awareness and offer a real opportunity for creativity and learning. However, if these tensions are not recognised and acknowledged, it can, at best, lead to a lack of fulfilment and disengagement, and at worst, result in a teacher leaving the profession.
Understanding the geography pipeline, and secondary geography teacher identity formation specifically, has the potential to offer practical applications not only for secondary geography teachers, but also for schools, teacher education and policy formation, ensuring both the recruitment of future secondary geography teachers and retaining those already in the profession
"The spawn of Romish frogs": to what extent were allegations of Roman Catholicism against early Quakers valid?
No full textDuring the Interregnum, the early Quakers’ critics repeatedly made allegations that Quaker doctrines and practices resembled those of Roman Catholics, and that Quakers were Jesuits in disguise. The objective of this dissertation is to investigate whether there was any merit in these allegations. This is achieved by, first, comparing Quaker and Roman Catholic doctrines relating to the topics which were the subject of the allegations, namely salvation, the priority to be accorded to the Spirit and Scripture, sin, and the sacraments. Thereafter an examination is made of the specific allegations, in each case asking whether Quaker beliefs aligned more closely to those of Roman Catholicism than to those of the Reformed faith. Finally, a comparison is made between the principal characteristics of Quaker and Jesuit spirituality. It is concluded that on the doctrines of salvation, the primacy of the Spirit over Scripture, the possibility of achieving perfection in this life, and the fact of direct communication by God with human beings, Quaker beliefs resembled those of Roman Catholicism and were opposed to those of the Reformed faith. It is additionally concluded that Quaker practices resembled Roman Catholic practices only in minor respects and that there was no merit in allegations that Quakers derived their beliefs from Roman Catholicism, had been taught by Roman Catholics, had been infiltrated by Jesuits or were Jesuits in disguise. Further it is found that there were significant similarities between Quaker and Jesuit spirituality. It is suggested that these conclusions enhance the credibility of Quakers’ claim that they derived their ideas and beliefs from their own spiritual experience. It is further suggested that Quakers should not properly by placed on the extreme radical wing of the spectrum of groups in mid-seventeenth century England within the Reformed faith
An interdisciplinary approach to understanding the TTP pathway
No full textDysregulated expression of inflammatory mediators as a product of complex immune and nonimmune cell interactions is a hallmark of chronic inflammatory diseases. Understanding and identifying drivers of dysregulated gene expression in the context of the inflammatory response enables researchers to understand pathogenic mechanisms better and to develop novel therapies. Much of this work previously focused on epigenetic and transcriptional regulators. However, changes in the transcriptome are not solely caused by changes in transcription. Posttranscriptional regulation of the stability and translation initiation of pro-inflammatory and immuno-modulatory mRNAs is a critical factor in determining their expression. The stability of mRNAs is controlled primarily by a set of RNA-binding proteins that recognise cisregulatory elements in the 3' untranslated regions. A prominent member of these proteins, TTP, vividly demonstrated, in several animal models, its role in the production of inflammatory mediators. TTP acts downstream of the p38 MAPK pathway as a regulatory switch between the on- and off-phase of the inflammatory response. Its regulation, however, is highly complex, and the dynamic interplay between the components involved is not yet fully understood.
This thesis aims to improve understanding of the dynamic regulation of the p38 MAPK-TTP signalling axis through mathematical modelling. A model based on ordinary differential equations and mass action kinetics was developed, describing TTP regulation by integrating the known properties of the components and interactions involved. To explore different properties of the model, two previously described p38 MAPK pathway models were adapted for integration with the newly built TTP model.
One of the resulting p38 MAPK-TTP models focuses on describing the pathway dynamics quantitatively, using data from bone marrow-derived macrophages and the murine macrophage cell line RAW274.7. The calibrated model was then challenged by computationally simulating pathway mutants and comparing the results with data obtained from such mutant mice. The results underscore the need for further refinements and extensions to our model. They specifically highlighted the importance of considering the role of TTP in inhibiting mRNA translation, which is often overlooked compared to its mRNA degrading properties. The results further emphasised that the phosphatase DUSP1, while important, is insufficient to describe p38 MAPK regulation within our model accurately. Additionally, the results of inhibitor experiments underscore the need for caution in interpreting previous results and designing future experiments regarding the TTP phosphatase PP2A, as it affects TTP regulation on multiple levels.
The second model qualitatively explores potential oscillatory p38 MAPK activation patterns and their impact on TTP. A set of genetic engineering tools was developed for application in live-cell microscopy to investigate the dynamics of TTP activation experimentally. Captured live-cell microscopy data suggested that the stress induced by the imaging conditions affects TTP subcellular localisation. Consequently, the microscopy conditions need to be optimised before going forward. A fixed microscopy time-course experiment utilising activated cells expressing distinct TTP mutants, which resulted in different TTP activity, showed no differences in subcellular localisation over time in contrast to the literature, which suggests localisation to P-bodies or the nucleus.
With this interdisciplinary work, we have designed mathematical and experimental toolkits to improve our knowledge of the p38 MAPK-TTP signalling axis, which is relevant to various inflammatory diseases
The phenomenology of violent loss: trauma, grief, and remembrance in the aftermath of terrorism in France (2015-2016)
No full textWithin a period of less than nine months between November 2015 and July 2016, France has twice been the target of mass terrorist attacks, claimed by ISIS, which caused the death of 130 people in Paris and 86 in Nice, sent shockwaves throughout French society, and plunged the country into successive states of emergency. Through the interpretive phenomenological analysis of the lived experiences of seven bereaved parents who lost a child in the 13 November 2015 Paris attacks and the Bastille Day vehicle-ramming attack in Nice in 2016, this thesis explores the complexity of violent loss to terrorism. Guided by the fundamental lifeworld themes in phenomenology – lived time, space, body, and human relations – the thesis traces the intricate ways trauma, grief, and remembrance intersect in the parents' narratives of loss and the enduring impact of the experience upon their experiential landscape.
While acknowledging the diversity of loss experiences, it considers how the trauma of violent loss permeates all dimensions of the parents' lifeworlds and disrupts their sense of identity and ways of being in the world, leaving them grasping for meaning. In view of the political circumstances of their bereavement, the thesis argues that the experience of violent loss to terrorism should not be viewed solely as a 'loss', thus disregarding the post-traumatic sequelae that eventuate when death involves institutional failures and the victims' anticipation of justice. Along with its insights into the workings of trauma and grief, the thesis also sheds light on the meaning-making commitments and affective practices of remembrance through which the bereaved seek to preserve the relational bonds with the deceased and re-commit to life and the world as to re-learn them.
Drawing on first-person accounts and sensory ethnographic observations at the sites of the attacks and during the judicial trials of the accused, the thesis emphasises the value of exploring the experiential dimension of extreme situations and how individuals attempt to make meaning out of them. It also highlights the importance of accounting for the researcher‘s positionality and self-reflexivity throughout the entire research process, thereby contributing to methodological and ethical debates on the implications of using qualitative methods when researching emotionally-laden topics
Wave intensity analysis in the pulmonary circulation and pulmonary haemodynamics in advanced heart failure
No full textWave intensity analysis (WIA) uses simultaneous changes in pressure and flow velocity to determine wave energy, type and timing of traveling waves in the circulation. It has the unique advantage over other impedance-based methods in that it analyses the pressure and velocity waveforms as successive wavefronts and not sinusoidal wavetrains. The analysis is performed in the time domain, allowing clinicians to intuitively relate the arterial waves to events in the cardiac cycle. In this thesis, I investigated WIA in patients with heart failure and durable LVAD therapy. I found that wave propagation in the pulmonary circulation in the context of heart failure was comparable with the systemic circulation; wave reflection was more likely at higher pulmonary arterial pressures and with lower pulmonary arterial compliance. There were no significant changes in wave propagation nor reflection associated with LVAD pump speed changes at +/- 300 rpm. I also investigated haemodynamic parameters associated with MCS usage following orthotopic heart transplantation and found that a lower pulmonary arterial pulsatility index (PAPI) is independently associated with MCS use for severe early graft dysfunction following heart transplantation. Using the same haemodynamic data, I also explored a stroke volume calculator derived from pulmonary haemodynamics. I found that after calibration, it was possible to track changes in stroke volume based on pulmonary pulse pressure, however, this calculator requires further validation using data from different patient cohorts. At the inception of the project, there was ambition to develop WIA into a clinical tool, however with the current technology, I conclude that this is not yet possible due to the difficulty in acquiring a clean velocity signal and the need for more data
Mass spectrometry profiling of proteins and their ubiquitin modifications in ageing skeletal muscle
No full textSkeletal muscle mass and function progressively decline with age. This decline is exacerbated in later life, contributing to the development of sarcopenia which is prevalent in many chronic diseases and a predictor of mortality. The molecular mechanisms driving this decline are not fully understood, slowing the development of pharmaceutical interventions. This thesis uses mass spectrometry to profile age-related changes in proteins and their ubiquitin modifications in mouse skeletal muscle to elucidate potential driving mechanisms of sarcopenia. We begin by reviewing the application of proteomics to study ubiquitylated proteins – termed ubiquitylomics – highlighting its application in skeletal muscle research. We developed a workflow designed to address challenges associated with skeletal muscle proteome profiling, later modifying the protocol to allow for the detection of ubiquitylated sites. Our workflow was applied on skeletal muscle obtained from young (6 month) and old (21-22 month) C57BL/6 male and female mice. Bioinformatics analysis of the proteomics dataset highlighted profound changes to extracellular matrix, mitochondria, energy metabolism, proteostasis, sarcomere and spliceosome proteins. Of note, we show that the unfolded protein response in the endoplasmic reticulum was a male-specific trait in our aged cohort. The ubiquitylomics dataset revealed age-related changes on sites from mitochondrial proteins, histones, ribosomal subunits and UPS-associated proteins. There was no clear relationship between muscle protein abundance and their ubiquitylation status, indicating a more complex mechanism than ubiquitin-mediated degradation. Ubiquitylation of histone H2B – increased during ageing of simpler organisms – was consistently downregulated in both males and females, occurring on an isoform not previously mentioned in the ageing field. Altogether, this thesis improves our mechanistic understanding of ageing skeletal muscle preceding sarcopenia, offering some potential targets for future research
An enquiry into the use of performative events in the conceiving of community: that being the achievement of group affirmation through the performed personalisation of a localised space-time.
Full text linkThis thesis explores the application of performance in conceiving a personal faith in a community that is no more than a moment of play endowed with fleeting significance. To aid a consideration of the material presented, it employs a triadic chronotope based model to demonstrate an actor's sharing (staging) a performance, the psychological impact (scripting) that defines one’s role, and the personal positioning (seeing) that drives the situating of that role. Each part is introduced with an example drawn from the wider world of performance, to then be supplemented by references to the views of thirty five individuals on the role of performances in their community. The outcome from the three inter related elements of the chronotope is seen to be influenced by the adoption of either an eastern or western ontological position. With positioning in mind, this work progresses towards an appreciation of Deleuze's concept of the Fold, and the possibility it affords for the application of a performance centred ontology that is reliant on the individual alone. Crucial to an appreciation of this thesis is the engagement of the reader as performer, for to interpret this text is as with any, the scripting a personal experience of a transient community
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