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Shape-shifting bubble-driven hydrogel microbots
Get PDFMicrobots are artificial swimmers engineered to perform complex tasks at the microscale including drug delivery, cargo transport, and non-invasive surgery. Historically, the design of microbots has advanced from basic rigid structures to more sophisticated flexible and active particles. This transformation has been driven by the use of soft and flexible materials like hydrogels, which offer low elastic moduli and, consequently, high deformability. These soft active materials hold the potential to enable microbot navigation through shape and volume transformations.
This thesis begins by showing that hydrogel-based bubble-driven rigid microbots with I, U, and S-shapes exhibit distinct swimming characteristics: pumping, translation, and rotation. While the manufacturing and experiments of this study were conducted by our experimental collaborators, we propose a mathematical model to provide physical insight into the bubble growth mechanism at the active tips. The findings of this study inspire us to explore the use of hydrogels to control microbot dynamics through shape transformations.
We proceed by investigating the deformations of active hydrogel-based filaments in Stokes flow. For this investigation, we propose a simple numerical model incorporating a bead and spring system with the method of regularised stokeslets. The bead and spring network captures the elastic deformations, while the method of regularised stokeslets accounts for the non-local hydrodynamic interactions between different segments of the hydrogel body. Simulations of porous filaments, representing hydrogels activated by single or double-tip forces, reveal periodic oscillations and motion patterns such as corkscrew motion and run-and-tumble behaviour, reminiscent of the motility seen in sperm and bacteria.
Finally, the same framework is adapted to model the volume and shape transformations of the responsive hydrogels. By combining responsive and non-responsive sections within the same hydrogel, we are able to control both the function and swimming characteristics of passive and active hydrogel bilayers. Additionally, we propose new smart microbot prototypes, including star-shaped structures, and suggest control mechanisms that integrate responsivity with activity. The findings of this dissertation offer guidance for designing shape-shifting active microbots, and the methodologies developed are broadly applicable to various problems in the study of artificial microswimmers and undulatory motion
Adolescents, social media, physical activity and wellbeing: co-producing a school-based intervention
Get PDFMost adolescents are inadequately physically active in relation to the reccomendations outlined by the World Health Organization. Simultaenously, social media has become an intrinsic part of adolescents’ lives and they are the first generation to have constant access to social media through smartphones. While untethered access to screens and the internet may provide barriers to physical activity, more work is needed to understand the influence of new technologies and how social media can be used as a resource for physical activity engagement.
Study 1 and 2 in this thesis aimed to develop a better understanding of the interaction between adolescent social media use and physical activity by co-producing and developing a school-based social media intervention. Study 1 used co-production activities with adolescents (n = 32) to better understand how schools could use social media to promote physical activity engagement. Study 2 extended this focus to adults and used focus groups and 1:1 interviews to further develop intervention ideas with school staff and parents (n = 24). Following the thematic analysis and thematics comparisons of the data from Study 1 and 2, an intervention was developed using complex intervention design actions. This included a change in focus from physical activity to mental wellbeing, and Study 3 tested the feasibility of a 7-Day Social Media Detox using mixed methods (surveys and interviews) with 146 adolescent participants and nine class mentors (form tutors) across three schools.
This thesis contributes to knowledge by providing new insights into how schools can approach social media use, through a focus on supporting adolescent autonomy and by developing adolescent capabilities in self-regulation. The data provides new evidence about the ways in which adolescents’ uses of social media informs physical activity engagement and mental wellbeing. Taken together, new evidence is provided on: (i) the time, affordances and content on social media that adolescents attend to and use; (ii) the role of schools in supporting adolescents’ uses of social media; and (iii) the key features of a school-based social media intervention that are acceptable and feasible to adolescents and teachers in Sweden
A systematic investigation of the applicability of datamining for the improvement of pedestrian safety
Get PDFExtensive research has shown advanced technology as a promising component towards improving the safety of pedestrians in an urban road environment. In GB, in 2017, evidence from a national database on road data (i.e., STATS 19) summed 1305 road fatalities, with pedestrian fatalities representing c.a. 25.7% of the total road fatalities. Datamining, the technique adopted in this study, is a process used to convert raw data into useful information. Fewer studies, however, have investigated a systematic approach adopting datamining techniques (e.g., ML) to assess its level of quality and consistency. Therefore, the applicability of datamining to reveal undiscovered pedestrian road-crash casualty patterns more efficiently was further explored. This work uses ML to examine casualty statistics during a one-year period in GB. The investigation includes data regarding pedestrian attributes, the road environment and its physical infrastructure. A key advantage of ML over conventional statistics is that with minimal human intervention, advance warnings are given independently when exposed to new data. The adopted technique here, explores discrete classification rules. From a range of classification algorithms and for the road data given, the FCM was applied for its proven degree of objectivity and response sensitivity. To this end, the results anticipate pedestrian road-crash casualties mainly for elderly male pedestrians during the day with fine weather, with permanent speed limits set at 30 mph, particularly when neither general nor pedestrian facilities are made available. New pedestrian safety measures may be recommended as in, appropriate publicity, introducing variable speed limits, and further research focusing on developing non- existing pedestrian safety models on a number of pedestrian physical facilities (e.g., footbridge, pelican)
Forensic healthcare workers working with sex offenders: treatment outcomes and staff well-being
Get PDFThe purpose of the current thesis is to explore how working with individuals convicted of a sexual offence impacts treatment outcomes amongst this client population and the well-being of staff involved in their care. Underlying psychological mechanisms such as attitudes and perceptions, workplace factors and the therapeutic relationship are focal points. Within the first chapter, background literature relevant to theories of sex offending, risk reduction through therapeutic interventions, and the well-being and attitudes of forensic staff is discussed. The second chapter presents a Systematic Literature Review exploring how the therapeutic relationship between therapists and individuals convicted of a sexual offence impacts treatment outcomes. The findings from the review conclude that a positive therapeutic relationship is related to desirable short-term treatment outcomes. Specifically, individuals convicted of a sexual offence in positive alliances demonstrate desirable changes in attitudes and behaviours related to their risk. The review highlighted the need to explore further the psychosocial concomitants of working with sex offenders. Chapter three critiques the Perception of Sex Offenders Scale (PSO). The critique proved that the PSO is a valid and reliable measure for assessing perceptions and judgements of sex offenders and is more efficient than most of its counterparts. It is also proposed that the scale is complementary to measures exploring other psychological processes, such as attitudes towards sex offenders. Chapter four describes a research project exploring psychosocial concomitants of forensic healthcare workers without professional qualifications working with sex offenders. Specifically, the study explores how forensic healthcare workers’ attitudes and perceptions towards sex offenders, as well as workplace arrangements such as environmental safety, quality of supervision, and co-worker support, predict workplace well-being. The results suggest favourable attitudes towards sex offenders and advantageous workplace arrangements increase workplace well-being. Contrastingly, certain negative perceptions of sex offenders are also shown to increase well-being. The complexity of findings emphasises the usefulness of exploring attitudes and perceptions as separate constructs when predicting well-being amongst forensic healthcare workers without professional qualifications. Additionally, the findings highlight the importance of maintaining adequate levels of environmental safety as well as providing good quality supervision. The final chapter provides a synthesis of the findings from each of the preceding sections and an overall conclusion of the thesis
Search for charged-lepton flavour violation in top-quark interactions using eµ final states with the ATLAS detector
Get PDFA search for charged-lepton-flavour violation in top-quark production and decay is presented.
The data analysed corresponds to 139 inverse femtobarns of proton-proton collisions at a centre-of-mass energy of 13 TeV delivered by the LHC and recorded by the ATLAS detector.
Two processes are studied; the first is the production of a semileptonically decaying single top quark in association with a pair of opposite-sign different-flavour leptons, the second is the production of a top-quark pair, where one top quark decays into a pair of opposite-sign different-flavour leptons and a light up-type quark, while the other decays into a leptonically decaying W boson and a b-quark according to the Standard Model.
The signal signature requires the presence of three leptons defined as electrons or muons,
and is thus characterised by the presence of one b-jet, up to one light-quark jet, and either two electrons and one muon, or one electron and two muons.
In the absence of a signal, an observed (expected) upper limit on the branching ratio of
BR(t -> eμq) < 1.6 (1.7) * 10^{-7} is set at the 95 % confidence level. An EFT interpretation is also discussed.
During Run 3 of LHC,
the elevated luminosity and pileup conditions call for advanced electronic systems to efficiently
trigger the physics objects.
Among the new processing units,
of high importance are the Feature Extractor (FEX) modules, responsible for identifying leptons and jets.
For the commissioning of these modules,
the design, testing and commissioning of a separate module, the FEX Test Module was needed.
In this thesis, the process of testing and commissioning this FPGA-based digital system is discussed.
Tests concerning the interpretation of incoming electrical signals as localised energy deposits in the ATLAS detector
by the electron FEX module firmware are also discussed briefly
Multilayered and multiple-text catena manuscripts on the Acts of the Apostles
No full textThis study examines Greek catenae (or ‘chains’) on the Acts of the Apostles, specifically focusing on a group of manuscripts that contain catenae enriched with multiple layers of scholia and reflect various compilations. The primary objective of this thesis is to understand the nature of these works and uncover the connections among different catena types present in Acts. Starting with an overview of the historical research in this field, this investigation develops innovative methodological approaches to identify the core characteristics of these catena types, which are categorised into distinct content units. Furthermore, it seeks to reconstruct the editorial stages involved in their formation, divided into separate phases of production, and explores their role in understanding the origins and development of the principal catena types, specifically the Pseudo-Andreas catena (CPG C150), Pseudo-Oecumenius catena (CPG C151), and Pseudo-Theophylact catena (CPG C152), along with the evolution of particular codices singuli (CPG C155). This research sheds light on previously unnoticed writings, elucidates how they establish connections between separate catena traditions, and provides insights into scribal practices, compilation techniques, and the reception of catenae during the Byzantine Era
The dynamic regulation of PRMTs and their substrates during the DNA damage response
No full textThe dynamic regulation of post-translational modifications (PTMs) during the DNA damage response (DDR) is critical to maintain genomic stability. The importance of arginine methylation in the DDR is becoming increasingly apparent, but how protein arginine methyltransferases (PRMTs) are regulated after DNA damage is still largely unknown. Here, we show that the PRMT5 substrate RUVBL1 is dynamically methylated after IR and olaparib-induced damage. We also characterised a novel PRMT1 substrate USP11, we show that methyl-USP11 regulates DNA end-resectioning by increasing PRMT1-mediated methylation of MRE11
Investigating the role of ATM kinase in synapse development and homeostasis
Get PDFMutations in Ataxia-telangiectasia mutated (ATM), a master regulator of the DNA damage response (DDR), result in early-onset cerebellar ataxia and neurodegeneration. There is increasing evidence of a neuronal-specific role for this ubiquitous kinase, and ATM both localises to synapses and is required for long-term potentiation. The mechanisms underlying its role in synaptic development and function are, however, unclear. Using the Drosophila third instar larval neuromuscular junction (NMJ), this thesis uncovers the requirement for presynaptic Drosophila ATM (dATM) in neurodevelopment, distinct from its function in the DDR. As with mammalian ATM, neuronal GFP-tagged dATM is predominantly cytosolic, forming foci within axons and synapses. Two processes which are held in delicate balance during the fine tuning of synapse development are oxidative stress and autophagy – each can promote synapse expansion, yet in excess are deleterious. Previous work has shown that cytosolic ATM interconnects these processes. Consistent with this, this thesis demonstrates that the function of presynaptic dATM involves its coordination of ROS signalling and autophagy through the conservation of the ATM-AMPK axis. dATM knockdown larvae exhibited sensitivity to excitotoxicity, while augmenting autophagy – both pharmacologically and genetically – alleviated the effects of dATM deficiency. Taken together, the evidence suggests a model in which dATM transduces presynaptic ROS levels, responding to increased ROS by activating the autophagic machinery to induce synaptic growth, while protecting the neuron from excitotoxicity
Novel measurement techniques for monitoring particulate matter: development, application and evaluation of a low-cost IoT sensor network
Get PDFPresented as a collection of articles, this thesis assesses the role of low-cost and Internet-of-Things (IoT) technology in monitoring of ambient particulate matter. Adapting an off-the-shelf low-cost optical particle sensor, an IoT enabled particulate matter sampler was developed, built, and tested in a range of environments. The sampler was designed with field deployment practicality in mind. Completely self-contained, AltasensePM was designed to use battery power and the latest IoT communications technology to enable easy installation onto existing street furniture. Although subject to limitations from covid-19 pandemic, this thesis is able to present exploratory analysis from the use-cases of low-cost sensors for particulate matter monitoring.
Field testing enabled the evaluation of AltasensePM device and the development of a site specific calibration method for tackling the effect of humidity on detected particle concentrations (Cowell et al., 2022). Sensors performed well in co-location with a reference instrument with average correlation coefficients (r2) between raw device data and reference instrumentation are 0.718, 0.703 and 0.543 for PM1, PM2.5 and PM10 respectively, and calibration improving performance. During this testing process, fluctuating performance over time was detected from the sensors. This insight into raw sensors data (which is not always shared when using commercial low-cost sensors), suggest that sensors are best suited to longer term averaging and stable environments. The raw data also suggested that the sensor is not independently monitoring PM10. AltasensePM devices were hosted on the Birmingham Urban Observatory, an open-access online platform for environmental data across the city of Birmingham, UK. The calibration method was automated as an online process, allowing the following work to utilise real-time air quality measurements from the AltasensePM alongside commercial air quality and meteorology sensors.
When deployed in a network, the low-cost PM samplers provided a novel opportunity to study particulate matter concentrations at previously unattainable spatial scales, in both indoor and ambient monitoring settings.
The indoor deployment took place in a typical UK suburban home, during the Covid-19 pandemic, and exposed how activity such as cooking elevated concentrations of PM1 and PM2.5 in rooms beyond the kitchen (Cowell et al., 2023a). The role of ventilation in reducing extreme peaks in concentrations was highlighted and when extrapolating data from this 7-week study to annual exposure levels, both 2021 and 2004 WHO Air Quality Guidelines were exceeded. The limitations of the sensor highlighted in chapter 2 were also reflected in the indoor performance of the sensor. Novel opportunities for automating indoor monitoring using IoT and Smart home devices could create unprecedented future insight into occupant activity and the impacts on PM, although there are security and privacy risks that will need to be resolved first.
For ambient monitoring, AltasensePM was integrated into an opportunistic nested network of sensors, bringing together commercial low-cost sensors deployed by the University and local authority and AltasensePM onto the Urban Observatory open-access platform. The live-stream of open access PM2.5 data from this network gave unprecedented, localised insight into PM concentrations across the city. The network performed very well in longer term regional averaging compared to the regulatory network at estimating city wide annual PM2.5 concentrations- with sensor network average for the period within 0.2µgm-3 of the regulatory average. It is unclear whether sensors are sensitive enough to detect roadside sources, or if other regional sources are more predominant in roadside locations. Sensor performance and local variability highlighted the importance of network design to ensure representative sampling of the city, and the opportunities that collaborations between various low-cost sensing users could provide.
Finally, following from this experience with sensor networks, an evaluation of the future role of IoT, low-cost sensors and live stream data in supporting the management of air quality is presented. Live-stream data from sensors such as the AltasensePM has been shown to have the potential to support digital twin technology, where real time decision making is enhanced by both model and live data streams simultaneously. However, the future of PM in countries such as the UK where there is a modal shift toward electric engine vehicles means that regional sources rather than local traffic sources are likely to become more important in air quality management. Any future digital twins will need to onboard national and international data sets to support such management. Here the best practice in managing data streams for air quality interventions via digital twins is discussed
Investigation of the effects of railway track quality on passenger comfort using onboard inertial systems
Get PDFCondition monitoring activities in railways are crucial for detecting track and vehicle faults early and minimising their disruptive effects. Nowadays, in-service vehicles are increasingly used due to their availability and low disruption. Installing sensors either on the axlebox, bogie or cab of these vehicles provides information that can be used for a wide range of applications.
This thesis describes the use of a set of inertial sensors installed onboard passenger vehicles for track quality and ride quality monitoring. A novel method for speed estimation is presented and complemented with a method to estimate distance using track geometry.
This work investigates the use of passenger comfort as an indicator of track quality, using current standards, and comparing the comfort results to track quality and driver reports.
Finally, the relevance of the location of sensors in the vehicle is discussed. Two case studies are presented to illustrate the impact of the orientation of the vehicle and direction of travel on the signal received
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