SACM - United Kingdom
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Item Restricted Does Learning to Perceive English Vowels Help in Perceiving English Lexical Stress? The Case of Arab Learners of English: A Longitudinal Study(Saudi Digital Library, 2025) Allehyani, Manal Abdullah; Smith, RachelThis thesis investigates whether there is a relationship between improvement in the perception of English vowels by Arabic speakers and their improvement in the perception of English lexical stress. Previous research showed that L1 vowel inventory affects the cues exploited to contrast L1 vowels. Arabic and English have different vowel inventories. English was found to rely on spectral, temporal, and intrinsic f0 (IF0) cues whereas Arabic is theoretically assumed to rely on its limited spectral cues due to its small number of vowels, in addition to duration and intensity. Of special importance in the perception of English vowels is their intrinsic f0, which along with F1, help in discriminating the different contrasts. Lexical stress locations in Arabic are phonologically determined by syllable weight and position, which makes Arabic a predictable stress language. Concerning the acoustic cues of Arabic stress, production studies have shown that duration and intensity are the two correlates of stress. On the other hand, lexical stress in English is acoustically signalled primarily by f0 in accented stressed syllables. I categorised three main hypotheses in the literature of L2 segmental, prosodic, and phonetic development. These trends either show that L2 learners improve by either reusing their native acoustic cues or features, reweighting their secondary and primary cues, or learning new cues through accessing Universal Grammar (henceforth, UG). In this study, I tested the learning hypothesis. I hypothesised that Arabic learners of English would initially rely on their L1’s limited spectral, durational, and intensity cues to categorise English vowels. With greater exposure to English, they were expected to expand their vowel space, resulting in learning to attune to IF0 as a perceptual cue to English vowels. This newly-learnt cue (i.e., IF0), I hypothesised, would help Arab learners of English to improve their perception of English stress, which is cued by reliance on f0. To test these hypotheses, three perceptual experiments were administered. One experiment tested the perception of the acoustic cues of duration, intensity, and pitch. The other two experiments tested the participants’ identification of stress locations in disyllabic nonsense words, and their discrimination of English vowels. Participants from Libyan, Jordanian, and Sudanese dialects were recruited for this study. The participants were tested twice with an interval of six months between the two phases to monitor their progress. Signal Detection Theory (henceforth, SDT) was used as an analytical tool to gauge the participants’ sensitivities in the different tasks in the two phases of the study. 1 The thesis addressed three questions, all focusing on change over time as represented by the effect of the participants’ sensitivity to individual acoustic cues (i.e., duration, pitch and intensity) on their perception of vowels and stress locations. First, whether the acoustic cues that affected the participants’ perception of vowels in the first phase would differ after six months of exposure to English. Second, whether the effect of the acoustic cues and vowels on the perception of English stress locations would change from their baseline patterns after six months of exposure to native English. Third, and most importantly, whether a relationship existed between improvement over time in the perception of English vowels and improvement in the perception of English stress. Generally, the results of this thesis did not support the learning hypothesis, but gave support to the reweighting hypothesis, which emphasises enhancement and redeployment of existing cues. The results of the first question showed that the learners of all dialects attended to their native perceptual cues of vowels through showing an effect of intensity and duration on vowel perception in Phase One. After six months of exposure to English, they reweighted their cues, exhibiting an effect of only duration when perceiving the same vowels. For the second question, the results broadly showed that the native cue of intensity in addition to vowels affected the perception of stress locations in Phase One, and the same cues affected their perception of stress locations in Phase Two. The main research question was whether there is a relationship between improving the perception of English vowels and improving the perception of English stress. Again, the results showed that the learners’ improvement in the perception of stress was affected by their improvement in the perception of intensity and vowels. This suggests that the learners improved by enhancing their L1 native cues in addition to vowels instead of learning to attend to a new cue, f0.13 0Item Embargo On-body Passive Patch Antenna to Enhance Wireless Power Transfer to an Implanted Antenna(Saudi Digital Library, 2025) Aldosari, Mohammed; Khamas, SalamRestricted content8 0Item Restricted Temperature and structural effects on singlet fission and intersystem crossing in organic semiconductor systems(Saudi Digital Library, 2025) Bu Ali, Eman; Clark, JennyIn this thesis, we investigate the fundamental mechanisms that contribute to triplet exciton generation in organic molecular systems, such as singlet fission, triplet-triplet annihilation, and intersystem crossing. We examine the effects of external conditions such as magnetic fields and temperature, as well as internal factors such as molecular structure, on exciton behaviours and triplet generation process. We initially studied the temperature and magnetic field dependence on photoluminescence of a diF-TES-ADT singlet fission system. We showed, through magnetic field-dependent photoluminescence spectroscopy and a range of different optical and magnetic resonance spectroscopic techniques, that singlet fission to form a weakly bound triplet pair state is highly temperature-dependent in this material. Then, we investigated the photophysical properties of different tetracene derivatives in solution, as well as illustrated the mechanism of triplet formation using excitation wavelength-dependent transient absorption spectroscopy. By providing a comprehensive analysis of the excited state dynamics, we showed excitation-dependent behaviour in a newly synthesized tetracene dimer and some monomers, displaying unique characteristics, along with the detection of ultrafast intersystem crossing triplet formation. Finally, we investigated the photophysical properties of a new synthesis macrocyclic parallel pentacene dimer. This dimer demonstrated an ultrafast intramolecular singlet fission process and selective generation of the quintet states. It also exhibits the longest room-temperature coherence time of a quintet state, to our knowledge at the time of publication, of 648ns.4 0Item Restricted Effects of Dietary Nitrate and Vitamin C supplementation on Blood pressure and Vascular Health in Humans.(Saudi Digital Library, 2025) Lbban, Eazaz Ali; Idris, Iskandar; Tsintzas, Kostas; Siervo, MarioEndothelial dysfunction (ED) and elevated blood pressure are key risk factors for cardiovascular disease, characterized by reduced nitric oxide (NO) bioavailability. Co-administration of vitamin C and inorganic nitrate (NO3¯) may reduce oxidative stress, boost the conversion of nitrite (NO₂⁻) into NO and elicit positive vascular effects. Systematic review and meta-analysis of 20 randomized controlled trials (890 participants) demonstrated that vitamin C supplementation significantly reduced systolic blood pressure, with greater effects in populations with type 2 diabetes (-4.6 mmHg) and essential hypertension (-3.2 mmHg). Cross-sectional analysis of the InChianti cohort (920 older participants) showed initial inverse correlations between dietary NO3¯ and blood pressure, and vitamin C with systolic blood pressure only, all becoming non-significant after adjustment for confounding factors. No significant interaction was observed between NO3¯ and vitamin C on blood pressure. Analysis of vascular biomarkers revealed that dietary NO3¯ intake maintained significant negative associations with reduced C-reactive protein (CRP) and symmetric dimethylarginine (SDMA) levels even after adjustment for confounders. Vitamin C intake was positively associated with increased homoarginine levels. The only significant interaction effect between dietary NO−3 and vitamin C was observed for L-arginine concentrations. In the experimental study on young healthy participants, combined supplementation of dietary NO3¯ (6 mmol) and vitamin C (1000 mg) for three days significantly reduced home systolic blood pressure, while no significant changes were observed with NO3¯ alone. The subsequent randomized crossover trial in overweight/obese middle-aged adults showed no significant changes in blood pressure across interventions but demonstrated that co-supplementation significantly improved flow-mediated dilation (FMD) and increased NO₂⁻ bioavailability compared to NO3¯ supplementation alone. In conclusion, age, adiposity and metabolic status appear to influence the blood pressure and vascular responses to dietary NO3¯ and vitamin C co-supplementation. While blood pressure responses varied across studies, consistent enhancement of NO₂⁻ bioavailability and improved endothelial function with combined supplementation suggests potential therapeutic applications. These findings highlight the importance of considering individual anthropometric and physiological factors in designing nutritional interventions for cardiovascular health.7 0Item Restricted Britain’s Stance on Saudi–Kuwaiti Relations (1897-1932)(Saudi Digital Library, 2025) Otayf, Wael Yahya; Tal, DavidThis thesis examines the politics and shifts in power between external and internal actors in the Arabian Peninsula, specifically the interactions between the leaders of Saudi Arabia (ʿAbdul ʿAziz bin ʿAbdul Rahman Al-Saʿud, the founder of the modern state of Saudi Arabia) and Kuwait (under Mubarak Al-Sabah, who ruled from 1896 to 1915, and his successors through to 1932), both in relation to each other and with the British, who were then the dominant foreign presence in the region. Previous scholarship tended to emphasise external considerations as the sole factor determining policy in the Arabian Peninsula during the early twentieth century, with the turning point in Saudi-British relations typically placed after World War I. This study addresses a gap in the literature by examining the significance of interpersonal relationships and informal diplomacy that emerged in the Gulf region in the late nineteenth and early twentieth centuries and examines how these shaped policy for decades to come. It finds the 1897–1915 period particularly critical to understanding Saudi-Kuwaiti-British relations, as illustrated by Mubarak's initial request for British protection in 1897 and the rise of Ibn Saʿud in 1902. Furthermore, the research focuses on Britain's stance on Saudi-Kuwaiti relations between 1897 and 1932 — that is, the role their relationship (Saudi-Kuwaiti) played in shaping and influencing British policy in the region. Thus, the research focuses more broadly on the role of Saudi-Kuwaiti relations in influencing British policy and vice versa, as well as the rise of Ibn Saʿud, whose ascent had the greatest impact on shaping these dynamics before, during, and after World War I. This research challenges prevailing assumptions about policy development and the role of local actors. By analysing primary source material in both English and Arabic, it provides a more nuanced understanding of early twentieth-century policy formation. It finds that private relationships, personal ambitions and negotiations between individuals were just as important as great power realpolitik in shaping the history of the region. It was also observed that economic considerations and border fluidity played key roles in shaping the region.17 0Item Restricted Faith-Based Humanitarianism: The Role of Islamic Values in Shaping Saudi Arabia's Regional Aid Strategy(Saudi Digital Library, 2025) Alsubaie, Faisal; Nthakomwa, MartinThis project investigates how Islamic values shape Saudi Arabia’s humanitarian aid strategy by analysing the historical evolution, strategic deployment, and operational dynamics of its flagship agency, King Salman Humanitarian Aid and Relief Centre (KSRelief). Drawing on a wide range of secondary sources, the research explores the intersection of faith, statecraft, and governance in the Kingdom’s aid practices. It finds that while KSRelief is framed in the language of Islamic ethics, zakat, sadaqah, and ummah, its institutional design is largely driven by geopolitical interests, global diplomacy, and soft power aims. The study critically examines the tension between ethical rhetoric and strategic execution, revealing that Islamic references are often instrumentalised rather than embedded in practice. In conflict settings such as Yemen, this dissonance becomes especially pronounced, raising concerns about ethical coherence and legitimacy. Moreover, the research highlights a lack of robust governance mechanisms, including limited community participation and independent oversight. Through thematic and conceptual analysis, supported by visual frameworks, the project challenges the assumption that state-led Islamic humanitarianism automatically translates into faith-consistent outcomes. I. Recommendations urge institutional reforms: integrating third-party audits, establishing participatory frameworks such as local zakat boards, disentangling aid from strategic interests, and ensuring Arabic-language transparency. These steps aim to realign Saudi humanitarian practice with the ethical foundations it invokes, fostering greater accountability and effectiveness in serving vulnerable populations.32 0Item Restricted The association of Community Health Workers visits on healthcare utilization in Brazil: An analysis of the National Health Survey 2013-2019 PNS(Saudi Digital Library, 2025) Albattat, Saud; Harris, Matthew; Hone, ThomasIntroduction Aims/Objectives Community Health Workers (CHWs) are cornerstones of primary healthcare systems worldwide, improving access, equity, and outcomes while reducing avoidable costs. In Brazil's Family Health Strategy, CHWs conduct regular home visits as a key intervention. However, whether these home visits actually increase healthcare service utilization remains unclear. The aim of this study is to examine the association between CHW home visit frequency over the previous 12 months and recent healthcare-seeking behavior, analyzing multiple access indicators. Methodology A cross-sectional analysis incorporated pooled datasets from 2013 and 2019 Brazilian National Health Survey data for residents 15 years of age and older. The exposure was CHW home visit frequency (any visit vs. never) in the previous 12 months. The outcomes examined were care-seeking (in the last two weeks), and healthcare utilization outcomes in the previous 12 months (doctor visits, hospitalizations, emergency visits, follow-up for chronic disease, preventive care whether from a physician or CHW, smoking cessation services, etc.). Prevalence ratios from survey-weighted Poisson regression with robust variance were estimated. All models were adjusted for sociodemographic and health-related factors. A complete-case analysis was conducted, with 95% confidence intervals. Results The majority of utilization indicators increased from 2013 to 2019 (e.g., any consultation 71.2% - 76.2%). After adjustment, any CHW home visit over the past 12 months was not associated with any two-week care-seeking (aPR 0.97, 95% CI 0.92–1.03) or secondary outcomes (emergency care, hospitalizations, chronic-disease follow-up, screening). Conclusion In this nationally representative Brazilian study, CHW home visits were not associated with healthcare utilization after controlling for sociodemographic and regional variables. Utilization was more strongly associated with the socioeconomic determinants than CHW visits would indicate in Brazil's universal system. Collectively, the evidence base suggests that CHWs have their impact mainly in health literacy and prevention, areas that are poorly captured by any utilization metric with a short recall period.31 0Item Restricted the impact of social inequalities on oral health and quilty of life in children and adolescents(Saudi Digital Library, 2025) Alosaimi, Budur; Bhujel, Nabina; Hosey, Marie Therese; Rajan, SadnaObjective: To conduct a scoping review of the literature on the impact of social inequalities on oral health and quality of life among children and adolescents. Methods: Relevant articles were searched for in the electronic databases MEDLINE, EMBASE, and the Cochrane Library, focusing on studies indexed with relevant MESH terms and following PECO criteria for selection. The process involved conducting searches in databases, reviewing titles and abstracts, assessing full texts, and manually searching reference lists. The risk of bias was assessed using a validated quality assessment tool. Results: In total, 397 studies were identified, and 21 studies were included in this scoping review, the full text of which was assessed for potential bias. All articles highlighted the prevalence of dental caries as a persistent health issue among young people, with Indigenous peoples and those from low-income families having higher risks and less favourable outcomes. The findings also revealed disparities in oral health and access to dental care, which are attributed to a complex interplay of individual, community, and environmental factors. Conclusion: Social inequalities largely drive oral health disparities, so interventions must address various socioeconomic determinants to improve oral health among disadvantaged children and adolescents. Further research should aim to clarify the causative factors and effective strategies to combat these inequalities for better oral health outcomes.5 0Item Restricted Detection of intracerebral haemorrhage in the prehospital setting(Saudi Digital Library, 2025) Almubayyidh, Mohammed; Parry-Jones, AdrianAim: This thesis aimed to improve the prehospital identification of intracerebral haemorrhage (ICH) in patients with suspected stroke. Methods: A scoping review was conducted to identify early clinical features and portable diagnostic devices capable of distinguishing ICH from other causes of stroke symptoms in prehospital settings. This was followed by a systematic review of existing prehospital prediction models for ICH, assessing their development, predictive variables and performance. Subsequently, prehospital data were used to develop and validate new prediction models for ICH detection. The identified predictors were then evaluated in combination with glial fibrillary acidic protein (GFAP) using clinical data. Results: The scoping review highlighted several clinical features that may help distinguish ICH from other suspected stroke cases. Promising portable devices, including microwave and ultrasound imaging, were identified; however, their capabilities and application in prehospital settings remain limited. The systematic review revealed substantial methodological limitations in existing prehospital prediction models, rendering them unreliable for practical use. Consequently, new prehospital prediction models were developed using logistic regression and a machine learning approach. These models incorporated nine predictors and demonstrated good internal validity, with optimism-corrected area under the curve (AUC) values of approximately 0.80. Calibration measures showed good agreement between predicted and observed outcomes. The combination of the identified predictors with GFAP achieved better performance, with an optimism-corrected AUC of 0.90. Conclusions: Prehospital care plays a pivotal role in determining outcomes for patients with ICH, as timely identification, treatment and transfer to an appropriate facility are critical. This thesis demonstrates the potential to distinguish ICH from other suspected stroke cases in the prehospital setting. The findings may ultimately enhance prehospital triage, reduce transport delays and minimise onset-to-treatment times for patients with ICH. Moreover, this work addresses important gaps in prehospital stroke care and provides a foundation for future research to refine and implement these strategies in practice, potentially leading to better outcomes for this high-risk stroke subtype.38 0Item Restricted Nonparametric Predictive Inference for Selection and Ranking(Saudi Digital Library, 2025) Alshihry, Fatimah Ibrahim; Coolen, FrankThis thesis introduces Nonparametric Predictive Inference (NPI) for selection and ranking, based on a single future observation from each group, and focuses on two main contributions. First, the development of NPI procedures for various selection and ranking events. Secondly, the application of different loss functions to quantify the loss incurred from non-optimal selection and ranking decisions. Initially, NPI is applied to rank the best groups within subsets. A selected subset refers to one or more independent groups that are better than the rest, where better means that all future observations from the groups in the selected subset exceed all the future observations from the non-selected groups. The ’independent group’ means that information about the random quantities for one group does not provide any information about the random quantities for another group. Two special cases are considered: selecting a ranked subset of the two best groups and the three best groups. For the subset consisting of two groups, the exact NPI lower and upper probabilities are derived for the event that these are the two best groups, while for the subset consisting of three groups, approximate NPI lower and upper probabilities are derived for the event that these are the three best groups. The thesis further explores a more general case of selection and ranking, addressing how to rank buckets containing one or more independent groups. Here, ’bucket’ refers to a cluster or grouping of independent groups. This approach tackles two key questions: how to allocate groups to buckets, and how to determine the optimal number of buckets—defined as the allocation that maximises or minimises the NPI lower and upper probabilities for a given event. Various allocation methods are evaluated, including those based on measures such as the median. Additionally, the NPI-Bootstrap method is used to estimate probabilities, to approximate the probability of the event of interest itself, rather than its lower and upper probabilities. Throughout the thesis, data from the literature illustrate and support the methods. In this thesis, the NPI method is applied across various selection and ranking events, using different loss functions to quantify the loss incurred from non-optimal selection and ranking decisions. Uncertainty is quantified by calculating the NPI lower and upper expected losses for the events corresponding to these scenarios. In the selection scenario, zero-one, linear, and quadratic loss functions are used in both pairwise and multiple comparisons. Several selection events are considered, including selecting the best group, selecting the subset of best groups, and selecting the subset that includes the best group. In ranking scenarios, zero-one and general multi-level loss functions are applied to ranked subsets of best groups. The zero-one loss function provides a binary measure of whether the ranking is correct, while the general multi-level loss function allows for a more nuanced evaluation by assigning penalties based on the specific ranking of groups according to the next future observation per group. For the general event of selection and ranking, linear and quadratic loss functions are used to evaluate the ranking of groups assigned to different buckets. The effect of the use of different loss functions on the selection and ranking decisions is illustrated by examples.7 0