SACM - Ireland
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Item Restricted Phytochemical studies on Lusitanian heath species and their effects on angiogenesis and melanogenesis(Saudi Digital Library, 2026) Khadijah, Jabal; Walsh, JohnOverview: The genus Erica belongs to the Ericaceae family, which includes approximately 4250 species and 124 genera. In Ireland, there are 14 species and 7 genera. Of these, the Lusitanian heaths, Erica erigena, Erica mackayana, Daboecia cantabrica and Erica × stuartii, represent an underexplored group of plants in terms of their phytochemical composition and biological properties. Aims of the work: The overall aim of the work described in this thesis was to carry out a phytochemical analysis of the triterpenoid constituents in the Lusitanian heaths and secondly to determine their potential in in vitro and ex vivo angiogenesis and anticancer assays. An additional aim was to profile the flavonoid glycoside constituents in the Lusitanian heaths and determine their effects on melanogenesis using a melanoma cells line (FM55) and cells from a donor patient (NHEM). Materials and methods: The plants used in the study were collected from different areas in counties Mayo and Galway. The identity of each plant was confirmed with specimens deposited in the Trinity herbarium. Phytochemical analysis on the triterpenoid constituents in the Lusitanian heaths was conducted using GCMS with N,O-Bis (trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TCMS) used as the derivatizing reagent. HPTLC, HPLC and NMR analysis were carried out on the phenolic-rich fractions. Human umbilical vein endothelial cells (HUVEC) and prostate cancer cells (PC-3) were used to test compounds/quantified extracts in cellular viability, migration and invasion assays. The ex vivo aortic ring assay was used to evaluate the antiangiogenic and vasculature disruption effects of test compounds/extracts. The anti- melanogenic activity of the flavonoid-rich extracts on cellular melanogenesis was conducted using both the melanoma cell line, FM55 and NHEM cells from a donor patient. Results and discussion: In E. erigena, the triterpenoid composition varied by season, geographical location and plant part used, with the leaves collected in January exhibiting the highest overall content (59,204.62 ± 1021.03 μg/g). Lupeol levels in the leaves significantly decreased throughout the year, dropping from 14,590.47 ± 267.64 μg/g in January to 5,048.03 ± 229.32 μg/g in September. Notably, the presence of micromeric acid was confirmed by NMR and GC-MS for the first time in Erica species. The analysis of the coumaroyl triterpenes in E. erigena posed challenges as these compounds rapidly isomerized between their cis and trans forms and co-eluted from the flash column with ursolic aldehyde and other minor constituents. Separation of the coumaroyl triterpenes from the other co-eluting triterpenes was achieved through a methylation reaction, followed by their isolation using flash column chromatography. Their identity as conjugates of lupeol, α-amyrin, and β-amyrin was confirmed by NMR spectroscopy and synthesis of each individual isomer. An important step in their synthesis involved using UV light at 366 nm to convert the trans coumaroyl triterpenes to their cis counterparts. Scanning electron microscopy was used to botanically distinguish E. mackayana, E. tetralix, and E. × stuartii from each other. Phytochemical differences between all three plants were determined by GC-MS with notably lower levels of triterpenoids in E. mackayana. The highest triterpenoid content was found in the leaves of E. tetralix, 38,229.83 ± 367.16 μg/g, while the lowest level was recorded in the flowers of E. mackayana, 24,936.54 ± 565.59 μg/g. Samples of D. cantabrica were collected from nine locations across counties Mayo and Galway. Analysis of D. cantabrica collections and cultivated D. cantabrica alba by GC-MS revealed distinct differences in their triterpenoid profiles depending on their area of collection. A notable difference between D. cantabrica and the other Lusitanian heaths studied was the absence of micromeric acid in D. cantabrica. In the cell-based assays, using HUVEC and PC-3 cells, the quantified fractionated extracts rich in lupeol, uvaol/erythrodiol, and ursolic acid were particularly effective as inhibitors of cellular proliferation, migration, and invasion of these cells as well as in the ex vivo aortic ring assay that determined their effects on angiogenesis and as vasculature-disrupting agents. In melanogenesis assays, the most promising extract identified was the EEF extract, which reduced melanin content in FM55 cells. Among the eight extracts tested, EEF and the compounds EEL-MR, EEL-MG, EEL-QR, and DCF-MR- 5-ME demonstrated significant depigmentation of NHEM cells compared to the control group. Conclusion: The Lusitanian heaths represent an interesting subclass of plants with their secondary metabolite constituents demonstrating potential as angiogenesis and melanogenesis inhibitors. Further studies are required at the phytochemical level to fully characterize the minor constituents present in the Lusitanian heaths. This will necessitate their isolation with follow-on studies required to assess their true potential in angiogenesis and melanogenesis assays. While the pentacyclic triterpenes were evaluated against viability of PC-3 cells, a more extensive panel of cancer cell lines should be used to determine the true potential of these constituents in the Lusitanian heaths against a wider panel of tumour cell lines.15 0Item Restricted Effectiveness of Immersive Virtual Environments in Learning 3D Transformations in Computer Graphics and Impact on Spatial Skills(Saudi Digital Library, 2026) Alobaid, Maha Abdulaziz; Manzke, MichaelWith the rapid advancements in virtual reality technology, new opportunities are emerging for enhancing learning experiences, particularly in disciplines that require strong spatial reasoning. However, it remains unclear to what extent immersive virtual environments can influence students' spatial skills, especially in complex subjects such as 3D transformations in computer graphics. This study explores the role of immersive virtual reality in improving spatial skills by evaluating its effectiveness in teaching 3D transformations through visual and interactive experiences. Over the course of several studies, our research has gradually honed in on the impact of immersive virtual environments on students' understanding of spatial concepts. Initially, the focus was on user engagement and satisfaction with virtual systems. As the research progressed, it became evident that the immersive nature of virtual reality and its interactive capabilities played a crucial role in improving spatial reasoning. Through a combination of pilot studies, one-group pretest-posttest designs, and expert evaluations, this work identifies how immersive virtual systems provide significant affordances for visual learning and interaction with 3D transformations. This thesis presents findings that suggest immersive virtual environments, by allowing students to manipulate and visualize 3D objects from multiple perspectives, enhance their spatial skills more effectively than traditional methods. Furthermore, the study investigates how expert evaluations of virtual effectiveness align with user experiences, ultimately highlighting the value of immersive virtual reality as a tool for teaching spatial reasoning in computer graphics. The results point to the potential of virtual reality not just as an educational tool but as a platform to reshape the way spatial learning is approached, particularly in STEM education.3 0Item Restricted Corruption, Accounting and Investment(Saudi Digital Library, 2025) Alsalem, Shatha; Robert, Gillanders; Michael, Breen; Murya, HabbashCorruption poses a significant threat to economic development by eroding investor confidence, deterring foreign direct investment (FDI) and weakening institutional quality. A growing body of literature suggests that improving governance structures, such as accounting standards and investor protection, can help mitigate corruption. This research explores the relationships between corruption, accounting, protection of minority investors (PMI), and investment through a systematic literature review (SLR) and empirical investigations. Chapter One outlines the research objectives, contributions, and key gaps in the literature. It introduces the concept of corruption, including its definitions, types, and anti-corruption measures. This provides the foundation for subsequent chapters linking governance tools to corruption control and investment outcomes. Chapter Two presents a systematic literature review (SLR) of studies published between 2000 and 2023, sourced from Scopus using keywords related to ‘Accounting’, ‘Auditing’ and ‘Corruption’. It examines how corruption relates to accounting, identifies recurring themes and gaps, and builds a solid foundation for the existing literature. The findings highlight international accounting and auditing standards, accounting education, accounting and audit quality, internal and external auditor roles, professional accounting bodies and New Public Management (NPM) as key mechanisms in combating corruption. However, the literature reveals inconsistencies in their effectiveness across institutional contexts, providing a strong foundation for the following empirical chapters. Chapter Three extends the investigation by empirically examining the relationship between PMI and corruption using data from 185 countries (2006-2018). Although PMI is negatively and significantly associated with perceived corruption, the analysis unexpectedly reveals a positive and significant relationship between PMI and actual experiences of corruption and bribery, suggesting that corporate insiders, i.e. directors, may strategically use informal payments to enhance firm value or signal stronger investor protection. The rule of law moderates this relationship. These findings are interpreted using several theories, such as management hegemony, stewardship, the hidden cost of bribery, and coordination game and bribery theory. Chapter Four examines whether PMI and accounting standards moderate the relationship between corruption and FDI, using panel data from 133 countries (2006-2017) with OLS and two-step GMM estimations. Findings indicate that stronger PMI or accounting standards can mitigate the negative effect of corruption on FDI, supporting agency theory. This research contributes to the literature on corporate governance and corruption by combining conceptual, review-based, and empirical insights. It highlights the importance of accounting and investor protection in addressing corruption, and attracting investment, offering practical guidance for policymakers, regulators, managers, investors, business leaders and researchers in promoting better governance and economic growth.7 0Item Restricted Biochemical changes of the insulin molecule due to functionalized surfaces: An investigation from a therapeutic perspective(Saudi Digital Library, 2025) Fagihi, Megren; Bhattacharjee, SouravInsulin therapeutics is the cornerstone in current diabetes management, especially while treating Type I diabetes. However, being a protein, insulin is known to demonstrate agglomeration when subjected to alterations in its biochemical environment, such as acidity, temperature fluctuation, coming in contact with hydrophobic surfaces, and agitation. This thesis describes a detailed and systematically designed study to investigate the curious case of insulin agglomeration, understand the mechanism(s) that drive such agglomeration, and realize the therapeutic impacts of such insulin agglomeration. To begin with, a detailed literature survey was conducted on insulin agglomeration, with or without fibrillation, and converge the available knowledge into a single discourse, which is presented as the Chapter 1 (introduction) of this thesis. This literature survey was followed by four experimental chapters (Chapters 2–4) where through a range of systematic and consistent experimental approach the phenomena of acidity-, heating-, and hydrophobic surface-induced insulin agglomeration was investigated. To characterize the insulin agglomerates, a broad range of analytic platforms, such as transmission and scanning electron microscopy, circular dichroism, nanoparticle tracking analysis, and zeta potential were used. Additionally, this thesis work also exploited the promise of advanced optical microscopy platforms, such as the confocal laser scanning microscopy and fluorescence lifetime imaging microscopy to probe the agglomerates and identify the varied segments of fluctuating acidity inside them. Taken together, the data was able to provide vital information on insulin agglomeration with a mechanistic understanding of what drives such agglomeration. An in vitro study was also conducted (Chapter 3) to find out if the insulin agglomerates generated due to heating at high temperatures (50°C and 65°C) were bioactive, and the results came positive. The Chapter 5 then explains another in vitro study where fluorophore-labeled insulin uptake in human hepatocellular carcinomaderived HepG2 cells was investigated with confocal microscopy. Finally, Chapter 6 summarized the findings, provide a few additional perspectives on overall realizations made through these studies, and prioritized some lines of research for future explorations.4 0Item Restricted Private Ordering for non-Muslims in the Gulf States (GCC); Administration of Justice and Constitutionalisation(Saudi Digital Library, 2025) Alqahtani, Nawaf Mutib; O'Dowd, JohnIn recent years, the member states of the Gulf Cooperation Council (GCC) have witnessed several socio-legal changes that coincided with their major economic plans to move away from their primary dependence on natural resources. Consequently, GCC governments are aware that part of the implementation of these plans largely depends on attracting foreign investors, entrepreneurs, and highly skilled workers to reside, not temporarily, but permanently. Several laws have been amended, including those governing residency, naturalization, and even property ownership, to create a favourable, attractive, and friendly environment for recent residents and newcomers (Muslims and non-Muslims). Regarding family matters for non- Muslims, the GCC differ in the applicable law (between Islamic, secular, and conflict of laws). This thesis primarily discusses the extent to which, remaining within the framework of Sharia law, the GCC states can ensure, through arbitration laws, that non-Muslims are adjudicated in family matters according to the law of their choice and thereby contribute to the achievement of their economic plans. To answer this question, the thesis first examines the position of Sharia law on the rights of non-Muslims, including the right to litigate according to their own laws. It then analyses the historical practice of Muslim states (from the rise of Islam until the fall of the Ottoman Empire) towards religious minorities regarding this right. It then examines comparatively the constitutions and laws of the Gulf states regarding the status of non-Muslims in family disputes. Finally, an international practice (specifically, New York and England and Wales) is studied as practical examples of how members of religious minorities can litigate (through arbitration) according to their religious laws. The research methodology used to answer the main question and sub-questions is mainly doctrinal, comparative, and historical- legal and partly socio-legal. The thesis concludes by proposing a constitutional amendment and some legal reforms that would be consistent with the framework of Sharia, while still meeting the economic objectives of the GCC states.6 0Item Restricted Critical Analysis of Public Enforcement of Competition Law in Saudi Arabia with Reference to Egypt and the European Union(Saudi Digital Library, 2026) Alhamami, Abdullah Ahmed T; Maher, ImeldaCompetition law is a recent development in Saudi Arabia, with the first law issued in 2004. Initial enforcement was ineffective due to legislative and institutional shortcomings. Significant reforms established an independent competition authority and updated legislation. Combined with nearly two decades of enforcement experience, these developments make it timely to examine how public enforcement of competition law can be optimised in Saudi Arabia. The research employs legal- doctrinal and comparative methodologies, focusing particularly on Egypt and the European Union as key benchmarks. A socio-legal approach, including institutional analysis and elite interviews, complements the study due to the scarcity of published decisions and academic literature on Saudi competition law. The thesis examines four central aspects of public enforcement: the objectives of competition law, the enforcement toolkit, institutional design and judicial review. The analysis begins with the Saudi legal system's foundational influence on competition enforcement. The Competition Law identifies multiple broad objectives. Yet, these broadly defined goals lack hierarchical order or substantive interpretation by agencies or courts, creating uncertainty in enforcement priorities. The law provides various enforcement tools, including fines, leniency programmes, settlements and compliance mechanisms. Fining policies have evolved from fixed amounts to turnover-based calculations, though fixed fines remain prevalent in practice. Leniency and settlements represent positive steps, but their conflation within a single legal provision has led to operational ambiguity. Compliance programmes are promoted but lack financial incentives such as fine reductions, potentially limiting their uptake. Institutional independence has improved with the establishment of the GAC. However, ministerial representation on its board undermines autonomy. A shortage of academic expertise in competition law and economics further constrains capacity. While the GAC holds exclusive enforcement authority, ineffective cooperation with sectoral regulators risks undermining its efficacy. International engagement remains limited, with only one cooperation agreement signed with Egypt. Judicial review by administrative courts is crucial for ensuring enforcement legitimacy, but the absence of published case law hinders analysis. Specialised training for judges along with specialised court divisions, could significantly improve judicial outcomes. This thesis concludes that, despite progress, strategic refinements in enforcement practice, institutional autonomy and judicial expertise are essential for a robust competition regime in Saudi Arabia.18 0Item Restricted Rank distributions of graphs over the field of two elements(Saudi Digital Library, 2025) Safarji, Badriah; Quinlan, O’Brien; Cian ,RachelA square matrix $M$ represents a graph $\Gamma$ if its nonzero off-diagonal entries encode the adjacencies of $\Gamma$ according to a fixed vertex ordering. Over the field of two elements, we study the distribution of ranks within the affine space of all matrices representing a particular graph. The motivating question is which graphs of order $n$ are represented by more matrices of rank $n-1$ than of rank $n$. This reflects the fact that the most frequently occurring rank is not $n$ but $n-1$ in the space of all $\mathfrak{n} \times \mathfrak{n}$ matrices over $\mathbb{F}_2$, a property which is exceptional to $\mathbb{F}_2$. This thesis focuses on connected graphs that have a path or cycle as a subgraph induced on all but one vertex (called the extra vertex). The path graph $\mathrm{P}_{\mathrm{n}}$ serves as the starting point of this study. The path graph is fundamental in the related and widely studied minimum rank problem, and provides a foundation for our later analysis of the set $\mathcal{G}^{\mathrm{P}}$ of graphs containing an induced path on all but one vertex. A main result is a characterisation of all such graphs that are represented by more matrices of rank $n-1$ than rank $n$ over $\mathbb{F}_2$. This is achieved by first examining the vectors in the nullspace of each matrix representing $P_n$. An expression for the difference $\alpha(\Gamma)$ between rank $n-1$ and rank $n$ representations of a given graph $\Gamma \in \mathcal{G}^{\mathrm{P}}$ is determined in terms of these nullspace vectors. A recurrence is then established, expressing $\alpha(\Gamma)$ in terms of $\alpha$ for graphs in $\mathcal{G}^{\mathrm{P}}$ for which the extra vertex has lower degree than in $\Gamma$. We classify all $\Gamma \in \mathcal{G}^{\mathrm{P}}$ satisfying $\alpha(\Gamma)<0$ by first classifying those for which the extra vertex has degree 1, then using that to simplify and classify the degree 2 case, and continuing like this until it is shown that no such graphs exist for degree $\geqslant 6$. We then turn to the analogous problem for the cycle graph. We show that half of all $\mathbb{F}_2$-matrices representing $C_n$ have rank $n-1$, approximately one-third have rank $n$, and approximately one-sixth have rank $n-2$. We then investigate the set of graphs containing an induced cycle on all but one vertex, denoted by $\mathcal{G}^{\mathrm{C}}$. Our analysis reveals essential structural contrasts between the classes $\mathcal{G}^{\mathrm{P}}$ and $\mathcal{G}^{\mathrm{C}}$ : while the degree of the extra vertex is bounded in the path case, it can be arbitrarily large in the cycle case. An infinite family of graphs called alternating wheel graphs demonstrate this contrast, as there exists an alternating wheel graph $\Gamma \in \mathcal{G}^{\mathrm{C}}$ with an extra vertex of any even degree $\mathrm{d} \geqslant 4$ satisfying $\alpha(\Gamma)<0$.5 0Item Restricted Transcriptomic and Functional Analysis of Two-Component Systems AdeRS, BaeRS, GacAS in Acinetobacter baumannii AB5075(Saudi Digital Library, 2025) Sulimani, Maha; Kröger, CarstenAntimicrobial resistance constitutes one of the most significant global health challenges of our era, with Acinetobacter baumannii becoming a key priority pathogen owing to its extraordinary capacity to withstand various classes of antibiotics. A primary factor contributing to this resilience is the function of regulatory proteins, especially Two-Component Systems (TCSs), which allow the bacterium to detect environmental cues and swiftly modify gene expression. Nevertheless, the overarching regulatory networks of these systems are still not well comprehended. The objective of this thesis was to examine the regulatory functions of specific two-component systems (TCSs) AdeRS, BaeRS, and GacSA in A. baumannii AB5075, as well as to investigate their roles in antimicrobial resistance and various adaptive phenotypes. Through transcriptomic analysis (RNA-seq), I detected genome wide expression alterations in mutant strains that lacked these regulators when compared to the wild-type during exponential and stationary growth phases. Phenotypic assays, which included minimum inhibitory concentration (MIC) determination, disk diffusion, phenotypic microarrays and growth assays, were conducted to establish a correlation between transcriptional changes and antibiotic susceptibility and metabolism. In order to delve deeper into gene regulation, transcriptional start sites (TSSs) were delineated through differential RNA-seq, which facilitated the identification of promoter motifs and offered insights into the structure of transcriptional regulation in A. baumannii. Moreover, chromatin immunoprecipitation coupled with sequencing (ChIP-seq) was utilized to comprehensively map the binding sites of essential transcription factors (AdeR, BaeR, and GacA), uncovering their direct regulons and preferences for DNA binding. The results outlined in this thesis enhance our comprehension of TCS mediated regulation in A. baumannii. They reveal that AdeRS, BaeRS, and GacSA are responsible not only for the regulation of antibiotic resistance factors but also for affecting wider physiological mechanisms that aid in bacterial survival and adaptation. A comparative transcriptomic analysis of the adeRS, baeRS, and gacSA two-component systems has unveiled distinct regulatory effects on gene expression in Acinetobacter baumannii AB5075. Both adeR and adeS mutants exhibited numerous transcriptional alterations, particularly a downregulation of the adeABC efflux pump genes, thereby confirming their involvement in the regulation of antibiotic resistance. In the baeRS system, baeS demonstrated a more extensive transcriptomic influence compared to baeR, especially under the Late Stationary Phase LSP condition, where baeR was found to regulate only two genes. The gacA and gacS mutants revealed the highest number of differentially expressed genes across all systems, with gacA notably regulating the small RNAs sRNA100 and sRNA99, as indicated by peaks observed in chip seq data. The phenotypic characterization conducted through Kirby–Bauer disk diffusion assays indicated that all adeRS, baeRS, and gacSA mutants displayed measurable inhibition zones against specific antibiotics, implying partial changes in their susceptibility profiles. Nevertheless, minimum inhibitory concentration (MIC) testing revealed that these mutants continued to exhibit resistance, suggesting that although the regulatory disruptions influenced gene expression, they were not adequate to completely undermine the antibiotic resistance phenotypes.4 0Item Restricted The Role of PP2A in VE-cadherin Modulation in Human Cerebral Microvascular Endothelial Cells(Saudi Digital Library, 2025) Alenazi, Fawza; Spiers, PaulThesis abstract: Introduction: The blood–brain barrier (BBB) is a highly specialised and dynamic interface that protects the central nervous system (CNS) by tightly regulating the passage of molecules between the circulation and neural tissue. This barrier is primarily maintained by brain microvascular endothelial cells interconnected through tight and adherens junctions. Among the components of adherens junctions, vascular endothelial (VE)-cadherin plays a pivotal role in maintaining endothelial cell–cell adhesion, vascular stability, and BBB integrity. Disruption or internalisation of VE-cadherin has been implicated in numerous neurological and systemic disorders, including stroke, inflammation, and Alzheimer’s disease. The function and stability of VE-cadherin at the plasma membrane are critically influenced by its phosphorylation status. Protein phosphatase 2A (PP2A), a major serine/threonine phosphatase, is recognised as a regulator of junctional protein dephosphorylation and endothelial barrier function. Notably, PP2A has been identified as part of the VE-cadherin interactome, and previous studies suggest that it contributes to the formation of epithelial tight junctions and the maintenance of barrier integrity. However, the specific role of PP2A in regulating adherens junction components, particularly VE-cadherin, at the BBB remains unclear. Aims: This thesis aimed to investigate the role of PP2A in regulating VE-cadherin abundance and the functional integrity of the BBB using in vitro models of human brain microvascular endothelial cells. Specifically, the objectives were to (1) determine how PP2A inhibition affects VE-cadherin abundance and BBB integrity, (2) determine the broader proteomic changes associated with PP2A inhibition, and (3) determine whether metformin, a PP2A activator, can counteract these effects. Methods: Human brain endothelial cells (hCMEC/D3) were treated with the PP2A inhibitor okadaic acid (OA). VE-cadherin protein and mRNA abundance, subcellular distribution, and vi junctional localisation were analysed using Western blotting, RT-PCR, subcellular fractionation, and immunofluorescence. Barrier function was assessed by transwell permeability assays. PP2A activity was quantified with a phosphatase assay, and the involvement of proteasomal or lysosomal pathways was tested using MG132 and chloroquine. Proteomic alterations following OA exposure were examined using microarray analysis and bioinformatic pathway/network tools. The roles of Rab11A and Rab5A were assessed using siRNA knockdown. The impact of metformin on PP2A activity and VE-cadherin regulation was evaluated by cytotoxicity testing, PP2A activity measurement, and time-course analysis of VE-cadherin abundance. Results: OA produced a concentration-dependent reduction in VE-cadherin protein (50–70%), accompanied by its loss from endothelial junctions and a marked increase in paracellular permeability. These effects occurred without cytotoxicity and coincided with a ~60% decrease in PP2A activity. VE-cadherin reduction was prevented by proteasomal inhibition and associated with increased ubiquitination, indicating that OA promotes proteasomal degradation of VE-cadherin. Proteomic profiling identified 104 proteins altered by OA, highlighting pathways related to ubiquitination, membrane trafficking, tight junction regulation, and neurodegeneration. Rab11A upregulation was detected; however, Rab11A and Rab5A knockdown did not prevent OA-induced VE-cadherin loss. Metformin did not restore PP2A activity or reverse VE-cadherin reduction at 24 hours, although early time- course data suggested a partial transient attenuation of OA’s effect at 10 hours. Conclusions: PP2A plays a critical role in maintaining VE-cadherin stability and BBB integrity. Inhibition of PP2A disrupts endothelial junctions by promoting proteasomal degradation of VE-cadherin, leading to increased barrier permeability. These findings reveal a mechanism through which PP2A dysfunction contributes to BBB impairment. Although metformin showed limited restorative capacity, early temporal effects suggest that modulating PP2A signalling may offer therapeutic potential for preserving BBB integrity under pathological conditions.7 0Item Restricted THE ROLE OF SAUDI ARABIC DIALECTAL VARIATION IN THE ACQUISITION OF SPECIFIC ENGLISH AFFRICATE AND FRICATIVE SOUNDS BY SAUDI EFL LEARNERS SPEAKING THE HWAITI AND HIJAZI DIALECTS(Saudi Digital Library, 2025) Alomeri, Haya Nassir Saleem; Pérez, Ana de PradaDespite the multifarious studies investigating the acquisition of English as a second language (L2) by Arabic-speaking learners, very few have examined the influence of learners’ dialects on their pronunciation of English consonants. Therefore, this thesis aims to explore the impact of L2 learners’ dialects on their pronunciation of the English affricative and fricative sounds. To achieve this goal, the articulation of the sounds /ʤ /, /θ/, /ð/, and /v/ by 40 female senior undergraduate Saudi learners (20 Hwaiti Bedouins and 20 Hijazi Urbans) at Tabuk University were recorded and then rated by two English native speakers. The main hypotheses were that Hijazi speakers would mispronounce /ʤ/, /θ/, and /ð/ because they are not part of their dialect yet they are part of the Hwaiti dialect and that both groups would devoice the phoneme /v/ by pronouncing it as /f/ because /v/ is not in the Arabic sound system. This thesis uses quantitative methods: a demographic information questionnaire, LexTALE English proficiency test, Arabic and English production tasks, along with statistical analyses of the collected data by using RStudio (2021). The errors are classified based on Flege and Bohn’s speech learning model (SLM) (2021). The theoretical framework is an amalgamation of milestone theories, mainly cross-linguistic influence (Bild & Swain, 1989; Tati et al., 2015; Odlin, 1989, 2012; De Angelis and Selinker, 2001), Eckman’s markedness differential hypothesis (1985), and Flege and Bohn’s SLM (2021). Each contributes to the analysis of cross-language interaction, phonological transfer patterns, and L2 phonetic learning. The main finding is that the two groups were affected by their dialect sound systems when producing the selected phonemes. Interestingly, the two heterogenous groups had similarities in the type (albeit not the frequency) of sound substitutions: they both pronounced /ʤ/ as [g] or [ʒ], /θ/ as [s] or [t], and /ð/ as [z]. Moreover, the most challenging phoneme to pronounce by the Hijazi group was /ʤ/ in the middle position of words, whereas for the Hwaiti group, it was /θ/, also, in the middle position. Future researchers can expand upon this study to include other dialects.10 0