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Environmental and human health risks from micro/nano-plastics
No full textMicro/nano-plastics (MN-Ps) constitute a significant form of plastic waste present widely across marine, freshwater, and terrestrial ecosystems and which has emerged as a global environmental challenge. Given the diverse size range and varied properties of MN-Ps, they efficiently permeate the food chain, potentially instigating environmental and human health risks. Recognising and addressing these environmental and human health risks are current global concerns and represent a research area where scientific understanding is currently limited. The overall thesis goal is to assess the environmental and human health risks associated with MN-Ps in food products in Ireland, utilising an established risk assessment framework. The literature review conducted as part of this study lays the foundation for a food safety risk assessment framework to assess the hazard potential of MN-Ps in the marine ecosystem on human health. This study conducts a review of the current state of the art regarding MN-P definition and characterisation, identification, toxicity, and risk assessment methodologies in marine and food systems. The primary pathway of human exposure to MN-Ps has been identified as food ingestion. MN-Ps may pose acute toxicity, (sub) chronic toxicity, carcinogenicity, genotoxicity, and developmental toxicity. MN-P toxicological properties and general quantitative and qualitative analysis methods used in risk assessment are summarised. As part of this study, a semi-quantitative hazard identification model was built to rank MP polymers of potential human health concerns emerging from marine exposure pathways and categorises three exposure probability factors and two hazard impact factors for inclusion in a screening strategy to calculate the final risk scores. The outcome of this study is to inform for better management of the most hazardous polymers, specifically PUR, PVC, PAN, ABS, and PMMA. Dietary HE assessment models on the potential internalisation probability to MN-Ps through vegetable, fruit, grain, and aquatic fish and fish products in Ireland were developed. Linear regression models for MN-P size-concentration relationships and the bioaccumulation factor were developed for HE assessment modelling. The estimated daily intake (EDI) of MPs for Irish adults was found to be in the order of (through) vegetables > fruit > grain (1.62 × 10^3 number/kg body weight/day) and fish and fish products (40.3 number/kg body weight/day). The EDI of MPs through fish and fish products was compared with the no observed adverse effect level with the margin of exposure approach to assess the risk exposure probability, which suggests nearly 70% population is at low risk and 30% at higher risk. The uncertainties of MN-P gene expression were also addressed in this study through a meta-analysis study. In the systematic approach, study characterisation was developed by quantitative analysis to categorise the selected data into DNA/mRNA - positive/negative sign groups. In the meta-analysis, effect sizes were calculated to enhance the robustness of pooled estimates for individual studies. Through subgroup analysis, practical, functional assessment violin plots were generated to determine the significant effect factors of gene expression (MN-P morphology, exposure duration, pathway, and associated toxicity) induced by MN-Ps, leading to a future investigation into the hazard characterisation. Related potential genotoxic responses were reflected on the specific gene endpoints that were classified based on the gene expression analysis, related reference gene and data form. Overall, this thesis developed a comprehensive risk assessment model to evaluate the potential risk from MN-Ps to the environment and human health. The findings will inform the public, food growers, producers and processors, and policymakers on potential exposure to MN-Ps and risk reduction, thus ensuring food safety and encouraging responsible use and disposal of plastic materials.2025-12-02 JG: Author's signature removed from PD
Design Methodology for Fractional-N Digital Frequency Synthesizers to Minimize System Jitter and Spurs
No full textDigital phase locked loops (DPLL’s) outperform charge-pump analog phase locked loops in design simplicity and power/area consumption, thanks to the full digitization of the time-to-digital converter (TDC) and digital loop filter; hence, they have become an attractive design option to serve as integrated frequency synthesizers for clocking, communication, radar, and instrumentation purposes. The adoption of coarse-resolution TDCs, e.g., 3-bit, 2-bit, and 1-bit (bangbang) TDCs, further reduces the hardware complexity and consumption for advanced DPLL synthesizers. However, their coarse quantization nonlinearity complicates the linearized analysis at both TDC-block and DPLL-system levels, which consequently makes it hard to perform accurate prediction and minimization of the system jitter and phase noise (PN). Furthermore, when using a digital Δ-Σ modulator to facilitate fractional-N frequency synthesis, the power of its quantization error (QE) can easily overwhelm the dynamic range of such TDCs and consequently cause nonlinear distortion that deteriorates the system PN/jitter. A priori cancellation of the QE by using a digital-to-time converter (DTC) before its injection into the loop is necessary in such fractional-N digital synthesizers. In DTC-enhanced fractional-N DPLLs, different genres of nonlinearities associated with the DTC have become the major nonlinearity concern of the whole system. Prior to the work described in this thesis, the detrimental PN and spurious responses caused by the DTC’s nonidealities, let alone their mitigation, were not fully investigated or explained in the literature. In this thesis, accurate analysis of the system jitter, PN, and spurs is performed. A jitter-minimization-oriented DPLL-design strategy and comprehensive DTC-enhancement techniques are provided. Together, these help to achieve the optimized digital synthesizer design with minimized system jitter and spurs. Behavioral simulations confirm the accuracy and effectiveness of the methods
Developing genetically engineered Escherichia coli to biorefine lactic acid from fermented second-generation feedstocks
No full textThe exponential global population growth has led to increased consumption of finite resources like oil, gas, and coal, resulting in heightened CO2 emissions and climate change. This has led a number of dependent sectors urgently seeking and implementing sustainable alternatives. Biorefineries, which convert biomass into marketable products and green energy, are one such technology, being considered. Lactic acid (LA) is a platform chemical that can exist in one of two stereoisomers D- and L-LA. Stereospecific LA is primarily produced by fermentation as opposed to chemical synthesis and has applications in various industries, particularly in the production of bioplastics like poly lactic acid (PLA). As commercial LA production through fermentation uses first-generation feedstocks which compete with food production, second generation feedstocks are being sought as a more sustainable alternative. However, issues such as the requirement of costly pretreatments and the formation of racemic mixtures by wild fermentation, exist. To address these challenges, this thesis proposes a bacterial-based biorefining technology based on engineered Escherichia coli strains which can selectively catabolise either D- or L-LA stereoisomer, thus producing an LA solution containing a single stereoisomer from second-generation feedstocks like organic household waste and grass silage leachates. Efforts were also made to remove impurities from wild fermentation LA broths, such as short-chain fatty acids (SCFAs). Genetically modified E. coli strains were developed to selectively remove SCFAs while preserving LA by adapting a wild-type E. coli which could not use butyric acid as a sole carbon and energy source, to produce a strain which was able to remove butyric, valeric and hexanoic acid while leaving LA in solution. As SCFAs are valuable chemicals in their own right, which have uses as building blocks for an array of green chemicals; in this thesis E. coli strains were developed and assessed for their ability to biorefine specific SCFAs in synthetic leachates. While these advancements show promise, further research is needed to optimise and scale up these processes for commercial applications. Nonetheless, the strains resulting from this thesis represent an advancement in the implementation of a microbial-based lactic acid downstream process in a biorefinery context
Writing Home: Haiti and Vietnam in the Autofiction of Dany Laferrière and Anna Moï
No full textThis thesis examines depictions of home in autofictional return narratives written in French by Dany Laferrière (Haiti) and Anna Moï (Vietnam): Pays sans chapeau and L’Énigme du retour, by Laferrière; Le Pays sans nom, L’Année du Cochon de Feu and Nostalgie de la rizière, by Moï. In these narratives, the narrators return to their homelands after having experienced exile. I investigate the ways in which these narratives illuminate the relationship between diaspora and home, more specifically by looking at former French colonies. I contend that the autofictional form of these return narratives functions as a means of renegotiating, and contesting, the relations in which the diasporic returns find themselves. The thesis departs from geographical understandings of home, which foreground the ways in which ‘home’ is produced materially, as well as socially, ideologically and imaginatively. This interdisciplinary study, drawing on postcolonial and gender theory alongside mobility and tourism studies, emphasizes the role of the diasporic returnee in shaping, reshaping and contesting spaces of home. Firstly, I examine depictions of domestic labour, in which the domestic servant appears as both an exploited tool in projections of domestic space and a disruptive figure in associations between family and home. Then I explore how these texts highlight and complicate tensions between mobility and immobility, which also evoke the associations between spatial and social mobility. Finally, I turn to the returnee narrator’s position as both visitor and guide in their homelands, and the function of these narratives in global consumption of place. Throughout my explorations of these aspects of home, these autofictional narratives call into question the position of the returnee narrator in the complex array of local and global power dynamics, affected by colonialism, gender and economic privilege. In doing so, they contribute to understandings of diasporic writing and the relationship between displacement, mobility and home
Regulation, Resistence, and Resilience: The Visual and Material Culture of Dublin's Female Street Traders (c.1870s-1920s)
No full textThis thesis undertakes an art historical study of street trading in Dublin, investigating both the makeshift economies employed by women in the city, and the range of visual media used to represent them. While a mode of survival for many women, street trading also maps the establishment and movement of enduring labour networks, including organisations and systems in place in contemporary major industrial cities, largely implemented and run by women. While this study primarily considers Dublin within a specific time frame, aligned with the introduction of legislation aimed at informal trading in Ireland from 1871-1926, it does so from a broader historical, geographical, economic, cultural, and social perspective. The visual culture of street trading does not simplistically provide an illustration of historical accounts, but instead suggests an alternative and rich history of the period, one that gives new agency and voice to its subjects. This research combines an analysis of the materiality and economy of images, with an exploration of the social and economic lives of female traders, contextualised within a period of rapid civic change in Dublin. Complexities which surround visual culture as a social, cultural, ethical and historical phenomenon are also considered within this research, contributing to a multi–faceted study which demonstrates the importance of visual documentary sources when researching otherwise-marginalised classes of society during this time frame in Ireland
General Practitioners Experiences and Training in Managing Youth Suicidality
No full textBackground: Youth suicidality is the second leading cause of death amongst 15 – 29-year-olds globally. Ireland is one of the few countries where youths are more likely to die by suicide than adults. GPs are established gatekeepers for the early identification and intervention of youth suicidality. Despite this, there is no standardised approach to GP youth suicide prevention training. Irish GPs were found to have low levels of youth suicide prevention and mental health training, while high numbers experienced a patient death by suicide. Research suggests inadequate levels of suicide prevention support in healthcare systems. Aim: The purpose of this thesis is to investigate General Practitioner (GP) experiences and training in managing youth suicidality. Method: A systematic review and narrative synthesis aggregated empirical evidence on the training received by GPs who work with youth presenting with suicidality. A qualitative study and reflexive thematic analysis explored GPs experiences in working with youth suicidality and training. Results: Limited research is evaluating the efficacy of GP training and education programs in youth suicide prevention. GP training increased levels of GP knowledge and confidence. Irish GPs are placed under significant strain to absorb systemic issues in accessing secondary care, resulting in the ongoing inappropriate management of suicidal youth. Conclusion: Addressing systemic barriers is essential to improve service provision and suicide prevention for at-risk youth. Future researchers may consider applying robust methodology and conducting increased RCT and qualitative research regarding the efficacy of GP training in youth suicide prevention.2025-10-29 JG: Author's signature removed from PD
An Exploration of Irish Primary Teachers’ Knowledge of the Science of Reading and How It Relates to Their Self-Efficacy for Teaching Reading
No full textIn Ireland, teachers have a central role in the identification, allocation of resources, and provision of intervention for children experiencing reading difficulties, yet little is known about Irish teachers’ knowledge and self-efficacy for teaching reading. Underpinned by a conceptual framework which focussed on teacher professional competence, these elements were studied in the present research. This observational, descriptive and cross-sectional study used a quantitative approach. An online survey which explored content knowledge of reading psychology and development, language structure, and self-efficacy to teach reading, was completed by 392 primary school teachers. Teacher characteristics associated with both knowledge and self-efficacy were explored. Findings suggested that teachers lacked certainty and also held a number of misconceptions regarding reading psychology and development, that they lacked knowledge of language constructs needed to explicitly teach reading and that they reported low levels of self-efficacy for teaching reading, particularly in relation to the nature of reading development. The importance of strong teacher knowledge and high self-efficacy when supporting struggling readers was emphasised. Findings showed a correlation between content knowledge and self-efficacy; however, it was noted that teachers often overestimated their knowledge. Implications for teacher training and professional development as well as education and educational psychology practice, were explored
Age-Related Telomere Dynamics in Bats
No full textUnderstanding the mechanisms underpinning ageing and exceptional longevity remains one of the central challenges in biology. Much of what is currently known about the ageing process has been derived from short-lived, model organisms. However, recent years have seen an expansion of studies involving wild, non-model species. Bats make up over 20% of all living mammals and possess extraordinary adaptations including laryngeal echolocation, powered flight, and a unique immune system that enables them to tolerate viral infections typically lethal in other mammals. Bats also exhibit extreme longevity given their body size with most species living far longer than similarly sized mammals. As a result, bats have emerged as a new model organism for ageing research. Telomeres, the nucleotide repeats that protect chromosome ends, are a key hallmark of cellular ageing and have been widely studied in both laboratory and wild species. However, telomere biology in bats remains underexplored. This thesis presents the most extensive comparative analysis of telomere dynamics in bats to date, encompassing >3400 bats across five species. In Chapter 2, I focus on early-life telomere dynamics in Myotis myotis, a long-lived, insectivorous bat. Using qPCR-based telomere length measures from 500 juvenile bats, I identify spring rainfall as the strongest predictor of telomere length in pups, with wetter conditions associated with longer telomeres. Despite this environmental sensitivity, early-life telomere length did not predict survival to the first year or longer-term survival. These findings suggest that while telomere length in M. myotis is environmentally plastic during development, it may not translate to fitness differences in a species capable of strong telomere maintenance. In Chapter 3, I present the first telomere study on Molossus molossus, a fast-flying tropical, insectivorous bat previously considered short-lived. Fieldwork in Panama involving multi-year mark-recapture sampling revealed a new longevity record of at least 13 years. I found no consistent evidence for age-related telomere shortening in this species. These findings parallel those in M. myotis, suggesting that telomere maintenance may be a convergent trait among potentially long-lived bat species despite their ecological differences. In Chapter 4, I conduct the largest comparative telomere study in bats to date, investigating the relationship between telomere length and age in >2900 bats across five species of differing lifespans, ecologies and life histories: M. myotis, Rhinolophus ferrumequinum, Rousettus aegyptiacus, Phyllostomus discolor, and M. molossus. Results here reveal dramatic interspecific variation in telomere dynamics. While M. myotis and M. molossus showed no correlation between telomere attrition and age, R. ferrumequinum and P. discolor exhibited clear age-related telomere shortening. R. aegyptiacus displayed a non-linear trajectory, with telomere length increasing in early life before declining. Additionally I investigate sex differences, finding that patterns varied across species, with no universal male or female bias. Finally, I explore potential molecular mechanisms underlying telomere maintenance through a comparative transcriptomic analysis across species. Expression profiling revealed upregulation of shelterin complex genes and DNA repair pathways (e.g., homologous recombination and ALT-like mechanisms) in species which display telomere maintenance with age. In Chapter 5, I synthesise the findings across all chapters and highlight their implications for ageing research. The data presented in this thesis demonstrate that telomere shortening with age is not a universal feature of mammals, and that bats possess diverse, species-specific strategies to regulate telomere dynamics. The integration of field-based mark-recapture methods with molecular and transcriptomic approaches offers a powerful framework for studying ageing in the wild
The Experience of ADHD in Romantic Relationships
No full textAttention Deficit Hyperactivity Disorder (ADHD) is now recognised to affect individuals beyond childhood and to have impacts that persist across the lifespan. It can affect many domains of psychosocial functioning including education, occupation, emotional wellbeing, and relationships. To date, research has been limited on how ADHD affects intimate relationships. The current thesis describes a research programme consisting of two studies aimed at addressing this research gap. Study One offers a systematic review of the literature on the impacts of ADHD in intimate relationships, examining the experience of both partners. The reviewed studies (n=8) consistently demonstrated the profound impacts of ADHD on both the individual with ADHD and their partner. It identified the shared experience of relational strain in ADHD-involved relationships and the individual ways in which partners navigated these. The systematic review highlighted the lack of research studies completed in this research area, particularly in a European context, as well as the need for future research to explore the experiences of both parties in the dyad. Study Two employed a qualitative design with secondary data that explored the experience of Irish individuals with ADHD within romantic relationships. The reflexive thematic analysis developed four themes and seven subthemes. The first theme, ‘Too Much and Never Enough: The Emotional Rollercoaster of Rejection Sensitivity’ conveyed the emotional intensity that people with ADHD experience in relationships, driven by rejection sensitivity and a deep-seated fear of abandonment. The second, ‘The Struggle for Stability: ADHD’s Battle Between Passion and Distraction’ portrayed the difficulty individuals with ADHD face in sustaining relational consistency and stability due to their inattention, impulsivity, and their heightened propensity for novelty-seeking. The third theme, ‘Between Partner and Caregiver: The Emotional and Practical Strain in ADHD Relationships’ described how executive
functioning challenges and emotional reliance can lead to relational imbalance, codependency, and caregiver-fatigue in romantic relationships. Finally, the fourth theme, ‘From Chaos to Clarity: The Role of Self-Understanding in Love’ illustrated the profound impact of personal insight and reflective sense of self in romantic relationships. Findings highlight the importance of relational recognition of ADHD as well as the importance of ADHD-specific therapeutic interventions that expand to meet their complex relational needs. Implications for clinical practice and future research are discussed and recommendations for practice and policy are outlined.2025-10-29 JG: Author's signature removed from PD
Corruption, Inequality and Trust in Latin America. Exploring citizens perceptions through a socio-legal perspective
No full textThis research investigates the differing perceptions of corruption, inequality and trust in public institutions in Latin America, focusing on Argentina and Uruguay. Despite sharing similar levels of institutional development, the two countries exhibit great contrasts in how citizens perceive corruption. Through a participatory research approach, this study employs focus groups to collect qualitative data from citizens in both countries, providing deeper insights into their views on corruption and trust in institutions. The research uses thematic analysis to identify key factors contributing to these differing perceptions. Cultural particularities, tolerance for wrongdoing, national reputation, compliance with rules and inequality of opportunities emerge as crucial elements shaping how corruption is perceived. Additionally, the presence of strong accountability mechanisms and a robust separation of powers are identified as significant influences on public trust and perceptions of corruption in both Argentina and Uruguay. These findings point to perceptions of corruption and trust having implications regarding democratic backsliding. In addition, they offer a rich, qualitative understanding that complements existing quantitative research, helping to explain disparities seen in survey results. This study sheds light on the complex relationship between corruption, trust, and socio-cultural dynamics, highlighting why corruption perceptions can vary so significantly even in countries with comparable institutional structures. It underscores the importance of cultural and institutional factors in shaping public attitudes toward corruption, beyond what legal frameworks alone can address. This research emphasises the need for anti-corruption strategies that are tailored to the cultural and institutional contexts of each country, in order to effectively build public trust and enhance governance. These findings are crucial for developing more targeted, impactful policies aimed at combating corruption and fostering stronger democratic institutions across Latin America.Check original file - ethics in appendices2025-11-21 JG: Author's signature removed from PD