Exponential time differencing methods and asymptotic behaviour of solutions of problems in ground water flow

We start this thesis with a numerical study of the convergence of the exponential time differencing (ETD) schemes and the semi-implicit Euler method for the Allen-Cahn equation and a reaction-convection-diffusion equation and also compare the accuracy and efficiency of these methods. Next, we solve the nonlinear convection-diffusion (green roof) model numerically using the ETD method and central difference approximation. This numerical solution is investigated for three different initial values for the saturation. Finally, we study travelling wave solutions and self-similar solutions for the green roof, in particular, for the two limiting cases of being close to a saturated region and a dry region. Travelling waves, in the form of fronts, are found for most realistic limiting values of saturation; travelling waves are also investigated for some limiting versions of the model. Self-similar solutions, valid for high or for low saturations, are additionally investigated

The Effect of Cervical Muscle Fatigue on Postural Stability during Immersion Virtual Reality

The visual system is part of the nervous system that enables an individual to scan their environment and assess distance to and from objects. The information captured form our navigating environment is communicated to the brain, which in turn makes the decision on how we respond to spatial orientation. This is particularly useful in helping with balance and determining direction of movement. Our posture and visual stability rely heavily on an efficient and processing of visual, vestibular, and proprioception afferent input. Erroneous sensory information from defective sensory organs may cause a person to experience feelings of lightheadedness, spinning and whirling sensations, and difficulty in maintaining straight posture. Few studies have examined the synergy between cervical spine proprioception and the vestibular ocular reflex (VOR) and as such, their impact on human VOR is less understood. The purpose of this study therefore was to investigate how motion sensitivity is impacted by neck muscle fatigue in normal healthy participants. The overall aim of the present work was to investigate whether impaired somatosensory information from the cervical spine, caused by neck muscle fatigue, would negatively impact postural stability in healthy young participants. Results indicated that healthy young participants who were fatigued had significantly poorer postural stability than those who were not fatigued (p\u3c 0.001). In Conclusion, our research suggests that when assessing motion sensitivity in patients complaining of dizziness with a history of neck trauma, one may consider that VOR dysfunction could have a cervical origin due to somatosensory disturbance, which may lead to poor postural stability

Numerical Algorithms for Polynomial Optimisation Problems with Applications

In this thesis, we study tensor eigenvalue problems and polynomial optimization problems. In particular, we present a fast algorithm for computing the spectral radii of symmetric nonnegative tensors without requiring the partition of the tensors. We also propose some polynomial time approximation algorithms with new approximation bounds for nonnegative polynomial optimization problems over unit spheres. Furthermore, we develop an efficient and effective algorithm for the maximum clique problem

AN EXPLORATORY STUDY OF E-LEARNING STAKEHOLDERS’ EXPERIENCES OF DEVELOPING, IMPLEMENTING, AND ENHANCING E-COURSES IN ONE SAUDI UNIVERSITY

The use of e-learning technologies is gaining momentum in all educational institutions of the world, including Saudi universities. In the e-learning context, there is a growing need and concern among Saudi universities to improve and enhance quality assurance for e-learning systems. Practicing quality assurance activities and applying quality standards in e-learning in Saudi universities is thought to reduce the negative viewpoints of some stakeholders and ensure stakeholders’ satisfaction and needs. As a contribution to improving the quality of e-learning method in Saudi universities, the main purpose of this study is to explore and investigate strategies for the development of quality assurance in e-learning in King Khalid University (KKU) in Saudi Arabia, which is considered a good reference university using best and ongoing practices in e-learning systems among Saudi universities. In order to ensure the quality of its e-learning methods, KKU has adopted Quality Matters Standards as a controlling guide for the quality of its blended and full e-course electronic courses. Furthermore, quality assurance can be further improved, if a variety of perspectives are taken into consideration from comprehensive viewpoints of faculty members, administrative staff, and students. This qualitative research involved the use of different types of interviews, as well as documents that contain data related to e-learning methods in the KKU environment. This exploratory case study was undertaken, from the perspectives of various participants, to understand the phenomenon of quality assurance using an inductive technique. The purposive sample comprises a total of 30 female and male participants to answer the research questions and provide robust information in terms of how the quality of e-learning development has been met in the KKU environment. The thematic analysis method developed by (Braun & Clarke, 2006) was carried out to analyse the data from the interviews and documents. The results revealed six main supportive factors that assist in ensuring the quality of e-learning in the KKU environment. Essentially, these factors are: institutional support, faculty member support, evaluation of faculty, quality of e-course design, technology support, and student support, which together have a remarkable positive effect on quality, forming intrinsic columns, connected by bricks leading to quality e-learning. In addition, in the course of improving e-learning quality, KKU encountered various challenges, some of which were overcome while others were not. Generally, Quality Matters standards are considered to have a strong impact on improving faculty members' skills and on the development of high-quality blended and full e-courses. It is, therefore, the recommendations and implications of the present study that quality assurance practices in e-learning methods can be enhanced and that future researches might shed more light on these recommendations

Synthetic lethality of flavonoids towards homologous recombination deficient cells through PARP inhibition

2019 Fall.Includes bibliographical references.Flavonoids can be isolated from many different sources such as plants, fruits, and beverages and they have long been associated with various health benefits. Both in vitro and in vivo studies have shown potential anti-inflammatory, anti-allergic, anti-viral, and antioxidant activities associated with these compounds. Previously published research has shown that the anti-cancer effects of flavonoids on BRCA2 deficient cells can be attributed to a PARP inhibitory mechanism. Therefore, thirteen structurally similar flavonoids were screened and identified as PARP inhibitory flavonoids. Seven different cell lines: Chinese hamster lung V79 cells, its BRCA2 deficient derivative V-C8 cells, gene corrected V-C8 cells, Chinese hamster ovary (CHO) wild type cells, rad51D deficient CHO cells (51D1), Human colorectal adenocarcinoma cells (DLD-1), and their BRCA2 knockout cells (DLD1 BRCA2-/- ) were used to assess the degree of synthetic lethality due to PARP inhibition. Colony formation and doubling time assays identified selective toxicity in DNA repair deficient cells for the flavonoids Kaempferol, Myricetin, Quercetin, Theaflavin and Epigallocatechin gallate. A Sister Chromatid Exchange (SCE) assay indicated Kaempferol, Myricetin, Quercetin Theaflavin and Epigallocatechin gallate exhibited a marked increase in SCE rate, which is indicative of PARP inhibition. These results were confirmed via an in vitro PARP inhibition assay. This study identified Kaempferol as a natural PARP inhibitor leading to potential lethality to BRCA2 cancers. All flavonoids identified as effective PARP inhibitors had similar structural components: hydroxyl groups on the 5 and 7 position of the A-ring, another hydroxyl on the B ring in the 4 position, and a C-2,3 double bond (a 4-ketone function)

Fluid Cultures and Identifications: The Intercultural Communication Experiences of Saudi International Students in the UK

This thesis is an investigation into the intercultural communication experiences of Saudi international students in the UK. It focuses on the friendship experiences that Saudi international students form with home and international students in order to engage in intercultural interactions. It further investigates how Saudi international students experience interactions with individuals from the opposite gender with whom they have limited interactions with in Saudi Arabia. Furthermore, the study focuses on the incidents that may motivate or demotivate Saudi international students from engaging in intercultural communication. Finally, this thesis considers the changes that the participants had introduced to their worldviews, identifications and practices as a result of their overall intercultural experiences in the UK. The findings show that 1) the participants’ identifications of in-group and out-group members were inconsistent and the boundaries between both categories were difficult to identify. 2) In contrast to studies, which suggest that Saudi international students are homogeneous Muslims who come from a collectivistic culture, the findings show that the participants had different worldviews and identifications and cannot be categorized in a fixed category. 3) The findings also illustrate that despite the segregation between men and women in Saudi Arabia, Saudi international students do not necessarily find interaction with individuals from the opposite gender challenging, as some literature claims. 4) The experiences that demotivated the participants from engaging in intercultural communication are not necessarily negative ones, since universities religious organisations, such as the Islamic Society, which was perceived positively by the participants, may also contribute to demotivating their attendees from experiencing intercultural communication. 5) The overall intercultural experiences in the UK had influenced the participants’ worldviews, identifications and practices on various levels. Thus, some participants introduced significant changes to their worldviews and identifications, others accepted changes that do not contradict with their understandings of religion, while others resisted any changes. Overall, the study argues for moving beyond essentialist descriptions for Saudi international students that describe them as a homogeneous Muslim group, coming from a collectivistic culture in a country where men are dominant over women. The study gives valuable insights and practical implications for UK universities and Saudi Cultural Bureaux abroad where Saudi international students form a noticeable number amongst other international students

Syllable structure and related processes in optimality theory :an examination of Najdi Arabic

PhD ThesisThis study is an investigation of syllable structure and related processes in one variety of Saudi Arabic. This is the variety spoken by inhabitants of Riyadh and villages near this city in Najd province, henceforth referred to as Najdi Arabic (NA). Although this dialect has been analysed by scholars including Johnstone (1963, 1967), Lehn (1967), Ingham (1971, 1982, 1994), Abboud (1979), Al-Sweel (1987, 1990), Prochazka (1988), Kurpershoek (1999), Alezets (2007), Alessa (2008), and Alghmaiz (2013), syllable structure and related processes in this dialect have not been accounted for within Optimality Theory (OT). Therefore, the main goal of this thesis is to show how OT, as an analytical framework, is utilized to produce a better understanding syllable structure and related processes such as CV metathesis, epenthesis, vowel shortening, and syncope in NA. Accordingly, the fundamental aims of this thesis are to examine phonological processes that have an impact on the syllable structure in this dialect and to show the insights about NA syllable structures and related processes that can be gained through OT analyses. The research draws on previous work on NA as well as other Arabic varieties more generally. Thus, the theoretical literature on syllables, syllable structures and syllable typologies are taken into consideration in the analysis of NA data. The data for this study are drawn from articles, essays, theses, and journals. These sets of data underwent my own judgment as an NA native speaker. In addition, 15 native speakers of NA were interviewed and consulted on the NA set of data in this thesis. There are four findings in this study. The first deals with the comprehensive analysis of syllable structure in NA, focusing on the types of onsets and codas as well as the weight of syllables in this dialect. The second extends to the comprehensive analysis that deals with the main phonological processes in NA, focusing on CV-metathesis, epenthesis, vowel shortening, and syncope. The third sheds light on the unified set of OT constraints that has been established to explain NA syllable structure and related processes within OT. Finally, the capability of OT to account for cross-linguistic variation is demonstrated by showing how language-specific constraint rankings based on one set of constraints accounts for CV metathesis, vowel epenthesis, and syncope in Najdi and Urban Hijazi Arabic (UHA)

Highly sensitive alkane odour sensors based on functionalised gold nanoparticles

We deposit dense, ordered, thin films of Au-dodecanethiol core/shell nanoparticles by the Langmuir-Schafer (LS) printing method, and find that their resistance at ambient temperature responds selectively and sensitively to alkane odours. Response is a rapid resistance increase due to swelling, and is strongest for alkane odours where the alkane chain is similar in length to the dodecane shell. For decane odours, we find a response to concentrations as low as 15 ppm, about 600 times below the lower explosive limit. Response is weaker, but still significant, to aromatic odours (e.g. Toluene, Xylene), while potential interferants such as polar and/or hydrogen-bonding odours (e.g. alcohols, ketones, water vapour) are somewhat rejected. Resistance is weakly dependent on temperature, and recovers rapidly and completely to its original value within the error margin of measurement. (C) 2011 Elsevier B.V. All rights reserved