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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Behavioural causes and consequences of sexual size dimorphism in an apex predator species

Nyqvist, Marina J. January 2012 (has links)
Individual differences within populations in a range of phenotypic traits are hypothesised to have important ecological and evolutionary implications. Variation in individual growth rates that result in corresponding variations in body sizes, including size dimorphism, is a particularly widespread feature of many animal populations. The increasing characterisation of consistent individual behavioural variations, unrelated to age or sex, is equally considered to have important fitness consequences. Our understanding of behavioural causes of size dimorphism remains weak, and few studies have investigated the relationship between individual behavioural consistency and growth variations in size dimorphic populations. The overall aim of this thesis is to identify the behavioural drivers that underpin observed growth variations and result in size dimorphism by using pike (Esox lucius) as a model species. The results show that early life growth is an important driver of sexual size dimorphism in this species. A subsequent focus on the juvenile life stages revealed that individual differences in movement and dispersal tendencies were related to growth and body size in wild pike. The findings indicate that intraspecific interactions such as size-dependent interference competition during the first year of life plays a key role in maintaining intraspecific size variation and size dimorphism in the wild population. Experimental work revealed the occurrence of a behavioural syndrome, where the rank order differences in the foraging behaviour between individuals were maintained across time and risk situation. This suggests that individual competitive ability is underpinned by a variation in boldness to forage under risk. The importance of a heterogeneous environment and presence of intraspecific competition pressure for driving habitat and resource segregation, and subsequently sexual size dimorphism, is discussed.
22

Natural processes in the degradation of open-air rock-art sites : an urgency intervention scale to inform conservation

Fernandes, Antonio Pedro Martins do Mota Batarda January 2012 (has links)
Open-air rock-art forms one of the most widely distributed categories of prehistoric material culture with examples recognized across the Old and New Worlds. It is also one of the most threatened features of human heritage and is susceptible to accelerated decay as a result of anthropogenic and natural processes. Much attention has previously been given to the impact of identifiably human activities and their mitigation, but the aim of this research is to redress the balance and focus on understanding the short-, medium-, and long-term impacts of natural processes. The main objectives of research are to identify open-air rock-art natural degradation causes, create a suitable method to assess the state of conservation of any given engraved outcrop of the Côa Valley rock-art complex and develop a urgency scale for conservation interventions. The urgency scale will be established by thoroughly examining a sample of the most – in terms of conservation – representative engraved outcrops. Since more than one thousand outcrops with rock-art still subsist today, it would be impossible to examine them all. Therefore, a sample comprising outcrops that possess most, if not all, of the variables that might affect stability and conservation state will be chosen. Some of the issues to consider are weathering and erosion of outcrops, or slope gradient and aspect of the hills where these are located. Such phenomena as biological colonization, rainwater percolation or chemical exchanges at surface level will also be analyzed. The expected end result of research is the creation of a method to determine the condition of outcrops and to identify methodically those in most urgent need of conservation. As a result, informed conservation action plans can be systematically tailored to suit specific natural conditions. Moreover, conservation interventions can be prioritized within a total universe of 1000 outcrops with rock-art.
23

Development of an in vitro model to investigate the effect of chemotherapeutic treatment on mesenchymal stromal cells

May, J. E. January 2010 (has links)
No description available.
24

Proteomic responses of uninfected tissues of pea plants infected by root-knot nematode, Fusarium and downy mildew pathogens

Ghazala, Al-Sadek Mohammed Salem January 2012 (has links)
Peas suffer from several diseases, and there is a need for accurate, rapid in-field diagnosis. This study used proteomics to investigate the response of pea plants to infection by the root knot nematode Meloidogyne hapla, the root rot fungus Fusarium solani and the downy mildew oomycete Peronospora viciae, and to identify potential biomarkers for diagnostic kits. A key step was to develop suitable protein extraction methods. For roots, the Amey method (Chuisseu Wandji et al., 2007), was chosen as the best method. The protein content of roots from plants with shoot infections by P. viciae was less than from non-infected plants. Specific proteins that had decreased in abundance were (1->3)-beta-glucanase, alcohol dehydrogenase 1, isoflavone reductase, malate dehydrogenase, mitochondrial ATP synthase subunit alpha, eukaryotic translation inhibition factor, and superoxide dismutase. No proteins increased in abundance in the roots of infected plants. For extraction of proteins from leaves, the Giavalisco method (Giavalisco et al., 2003) was best. The amount of protein in pea leaves decreased by age, and also following root infection by F. solani and M. hapla at six weeks post-inoculation. F. solani caused a decrease in abundance of isocitrate dehydrogenase, glycerate dehydrogenase, carbonic anhydrase, oxygen evolving enhancer protein 2 (OEE2), phosphoglycerate kinase, chloroplastic and one unknown protein. Some leaf proteins increased in abundance, and included heat shock-related proteins (HSP70) and two unknown proteins. Proteins that decreased in leaves following root infection by M. hapla six week post-inoculation were RuBisCo large subunit, fructose bisphosphate aldolase 2, carbonic anhydrase, OEE1, OEE2, OEE3, RuBisCo small subunit and a 28KDa ribonucleoprotein. Some proteins increased in abundance, such as HSP70, fructose bisphosphate aldolase 1 and trypsin. In contrast to the decrease in protein observed at six weeks post-inoculation, the amount of protein increased in leaves three weeks after inoculation of roots with M. hapla. Root infection by both M. hapla and F. solani caused a reduction in leaf area, and also a reduction in fresh and dry weight of the shoot and root systems. The use of digital imaging and visible and infra-red light to study the changes in leaves was explored in this study. A clear difference was visible between leaves from healthy plants and between those from M. hapla and F. solani infected plants when imaged using a normal digital camera. In contrast, no clear differences were noticed between leaves of healthy, M. hapla and F. solani infected plants when using an infra-red camera with 850 nm wavelength light. This study indicates that specific proteins are altered in abundance in leaves following root infection, and provides the basis for future studies to develop rapid diagnostic tests.
25

Cooperative diversity techniques for high-throughput wireless relay networks

Vien, Quoc-Tuan January 2013 (has links)
Relay communications has attracted a growing interest in wireless communications with application to various enhanced technologies. This thesis considers a number of issues related to data throughput in various wireless relay network models. Particularly, new implementations of network coding (NC) and space-time coding (STC) techniques are investigated to offer various means of achieving high-throughput relay communications. Firstly, this thesis investigates different practical automatic repeat request (ARQ) retransmission protocols based on NC for two-way wireless relay networks to improve throughput efficiency. Two improved NC-based ARQ schemes are designed based on go-back-N and selective-repeat (SR) protocols. Addressing ARQ issues in multisource multidestination relay networks, a new NC-based ARQ protocol is proposed and two packet-combination algorithms are developed for retransmissions at relay and sources to significantly improve the throughput. In relation to the concept of channel quality indicator (CQI) reporting in two-way relay networks, two new efficient CQI reporting schemes are designed based on NC to improve the system throughput by allowing two terminals to simultaneously estimate the CQI of the distant terminal-relay link without incurring additional overhead. The transmission time for CQI feedback at the relays is reduced by half while the increase in complexity and the loss of performance are shown to be negligible. Furthermore, a low-complexity relay selection scheme is suggested to reduce the relay searching complexity. For the acknowledgment (ACK) process, this thesis proposes a new block ACK scheme based on NC to significantly reduce the ACK overheads and therefore produce an enhanced throughput. The proposed scheme is also shown to improve the reliability of block ACK transmission and reduce the number of data retransmissions for a higher system throughput. Additionally, this thesis presents a new cooperative retransmission scheme based on relay cooperation and NC to considerably reduce the number of retransmission packets and im- prove the reliability of retransmissions for a more power efficient and higher throughput system with non-overlapped retransmissions. Moreover, two relay selection schemes are recommended to determine the optimised number of relays for the retransmission. Finally, with respect to cognitive wireless relay networks (CWRNs), this thesis proposes a new cooperative spectrum sensing (CSS) scheme to improve the spectrum sensing performance and design a new CSS scheme based on NC for three-hop CWRNs to improve system throughput. Furthermore, a new distributed space-time-frequency block code (DSTFBC) is designed for a two- hop nonregenerative CWRN over frequency-selective fading channels. The proposed DSTFBC design achieves higher data rate, spatial diversity gain, and decoupling detection of data blocks at all destination nodes with a low-complexity receiver structure.
26

Quantification of performance analysis factors in front crawl using micro electronics : a data rich system for swimming

Callaway, Andrew January 2014 (has links)
The aim of this study is to increase the depth of data available to swimming coaches in order to allow them to make more informed coaching decisions for their athletes in front crawl swimming. A coach’s job is to assist with various factors of an individual athlete to allow them to perform at an optimum level. The demands of the swimming coach require objective data on the swim performance in order to offer efficient solutions (Burkett and Mellifont, 2008). The main tools available to a coach are their observation and perceptions, however it is known that these used alone can often result in poor judgment. Technological progress has allowed video cameras to become an established technology for swim coaching and more recently when combined with software, for quantitative measurement of changes in technique. This has allowed assessment of swimming technique to be included in the more general discipline of sports performance analysis. Within swimming, coaches tend to observe from the pool edge, limiting vision of technique, but some employ underwater cameras to combat this limitation. Video cameras are a reliable and established technology for the measurement of kinematic parameters in sport, however, accelerometers are increasingly being employed due to their ease of use, performance, and comparatively low cost. Previous accelerometer based studies in swimming have tended to focus on easily observable factors such as stroke count, stroke rate and lap times. To create a coaching focused system, a solution to the problem of synchronising multiple accelerometers was developed using a maxima detection method. Results demonstrated the effectiveness of the method with 52 of 54 recorded data sets showing no time lag error and two tests showing an error of 0.04s. Inter-instrument and instrument-video correlations are all greater than r = .90 (p < .01), with inter-instrument precision (Root Mean Square Error; RMSE) ≈ .1ms−2, demonstrating the efficacy of the technique. To ensure the design was in line with coaches' expectations and with the ASA coaching guidelines, interviews were conducted with four ASA swim coaches. Results from this process identified the factors deemed important: lap time, velocity, stroke count, stroke rate, distance per stroke, body roll angle and the temporal aspects of the phases of the stroke. These factors generally agreed with the swimming literature but extended upon the general accelerometer system literature. Methods to measure these factors were then designed and recorded from swimmers. The data recorded from the multi-channel system was processed using software to extract and calculate temporal maxima and minima from the signal to calculate the factors deemed important to the coach. These factors were compared to video derived data to determine the validity and reliability of the system, all results were valid and reliable. From these validated factors additional factors were calculated, including, distance per stroke and index of coordination and the symmetry of these factors. The system was used to generate individual profiles for 12 front crawl swimmers. The system produced eight full profiles with no issues. Four profiles required individualisation in the processing algorithm for the phases of the stroke. This was found to be due to the way in which these particular swimmers varied in the way they fatigued. The outputs from previous systems have tended to be either too complicated for a coach to understand and interpret e.g. raw data (Ohgi et al. 2000), or quite basic in terms of output e.g. stroke rate and counts (Le Sage et al. 2011). This study has added to the current literature by developing a system capable of calculating and displaying a breadth of factors to a coach. The creation of this system has also created a biomechanical research tool for swimming, but the process and principles can be applied to other sports. The use of accelerometers was also shown to be particularly useful at recording temporal activities within sports activities. Using PC based processing allows for quick turnaround times in the processing of detailed results of performance. There has been substantial development of scientific knowledge in swimming, however, the exchange of knowledge between sport science and coaches still requires development (Reade et al. 2008; Williams and Kendall 2007). This system has started to help bridge the gap between science and coaching, however there is still substantial work needed. This includes a better understanding of the types of data needed, how these can be displayed and level of detail required by the coach to allow them to enact meaningful coaching programmes for their athletes.
27

Investigation of a novel MPCM-S based PV/T system

Ali, Samira Abdulla January 2017 (has links)
In order to meet energy conservation targets and minimize global warming effects, this research is aimed to rise the efficiency of the PV/T system. This research investigates the usage of microencapsulated phase change slurry (MPCM-S) to replace conventional cooling fluids such as water. The phase change materials (PCMs) are encapsulated in a polymer shell forming microencapsulated phase change materials (MPCM) to prevent leakage of the PCMs as well as increasing the thermal conductivity. Mixtures of (5%, 10% and 15%) of microencapsulated phase change materials in water (slurries) were investigated. The use of phase change materials (PCM) improves heat absorption from the PV module due to their high latent heat, consequently increasing thermal output of the system, and electrical output because the PV panel temperature is reduced. The research started with an intensive literature review covering all elements involved, and then the conceptual design of the experimental rig was developed. Theoretical investigations including a steady-state computerized simulation module were developed, this simulation validated depending on a previous research and showed good agreement with results from that published experimental study. This suggested that the computer module could successfully predict the operational performance of the module with satisfactory accuracy. A series of laboratory-based tests were conducted for a wide range of conditions and slurry concentrations. The results were compared to the computer simulation with the same parameters. It was found that the root mean square percentage deviations (RMSPE) between experimental and simulated results were generally under 4%, so considered acceptable for engineering application of PV/T system. A slurry concentration of 10% was found to give the best results. Under operational conditions of 10% MPCM concentration, 3000 Reynolds number and 600W/m2 solar radiation, an experimental test was conducted. The electricity and heat outputs of the system were 108 and 520 W respectively, the associated electrical and thermal efficiency were 14.1% and 68.8%, giving an overall efficiency of 82.9%. The economic analysis was carried out to investigate the feasibility of the MPCM-S based PV/T system in two different climates of Europe. It showed that the system generates higher annual electrical and heat of 488.29 and 2184.93 kWh in a hot climate (using Madrid as an example) than the annual electrical and heat of 323.12 and 1262.1 kWh for colder climate (Stockholm as an example). Consequently, the life cycle cost of MPCM-S based system per kWh were -0.068 and 0.019 GBP for Madrid and Stockholm respectively, and for water-based PV/T system were -0.038 and 0.028 GBP for Madrid and Stockholm respectively. Finally, the environmental effect of the system was investigated by calculating the life cycle CO2 emission reduction of MPCM-S based PV/T system in both climates, they were 11.75 and 6.9 tonnes for Madrid and Stockholm respectively, and for water-based PV/T system were 7 and 3.5 tonnes for Madrid and Stockholm respectively. Generally, the MPCM-S based PV/T system is more efficient than the conventional water-based PV/T systems as predicted, especially if it runs with 10% MPCM-S. It delivers higher electrical and heat outputs in hot climates in comparison with colder climates of Europe, consequently better economically and environmentally.
28

Identifying the critical factors that impact on the development of electronic government using TOE framework in Saudi e-government context : a thematic analysis

Alqahtani, Fahad Naser January 2016 (has links)
Background: Electronic government (e-government) systems are important across several dimensions, such as the public sector, business sector and the government itself, via the various organs of government. Hence, e-government systems consist of numerous factors, which play various roles in the success of e-government development and adoption. The most important factors from derived from dimensions that impact on the development, implementation and adoption of e-government which are technological, organisational, environmental, and social, also it is intended for and the government decision-makers involved. Therefore, the government of Saudi Arabia is seeking to improve its electronic services (e-services) and so this topic was attractive for the researcher, who in turn, has attempted to make a research contribution to the integration of an e-government system in the context of Saudi Arabia (SA). Aims and Objectives: The aim of this research was to identify insights into the critical factors revealed in a review of the relevant literature. The Literature Review shows that there have been few studies that have considered the critical factors in the development of e-government systems. This thesis is taking into account the experiences of senior government IT staff and the citizens such a system is intended to serve. To present a theoretical understanding of e-government development that based on Technology-Organisation-Environment TOE framework. Consequently, a conceptual framework for the successful development and adoption of e-government was subsequently proposed to improve government services in general and make savings in terms of time, cost and promote the e-services. Methods: Qualitative research data were gathered via 26, in-depth semi-structured interviews from two perspectives: first, from the point of senior IT managers view at four Saudi Ministries and second, from the standpoint of 10 Saudi citizens (five men and five women). Thematic analysis was carried out to identify the critical factors that derived technological, organisational, environmental and social dimensions which influencing e-government development in the Saudi context. Moreover, to highlight the issues to be taken into account when endeavouring to support e-government development in Saudi Arabia’s Ministries. Results: This research makes a significant contribution to understanding e-government development, as it essentially identifies the critical factors that should be targeted by the Saudi government in its efforts to develop e-government. This study therefore brings together these various factors into a single comprehensive conceptual framework, comprising the main elements to be considered when attempting to identify, improve and motivate e-government system development. This is based on the perspectives of senior government IT managers in Saudi Ministries and the intended system users, namely the Saudi public. As a theoretical basis (TOE) Framework was applied and extended to the topic of e-government system development. Conclusion: This research explains how the critical factors identified through the application of the TOE Framework plus the examined social dimension can be worked into the Saudi government’s decision-making, as it provides valuable information for decision-makers in Saudi Arabia’s Ministries about what needs to be consider, thus enhancing the development of e-government nationwide.
29

Investigating information trust, professional ethics and risk when embracing e-government : an empirical study of Kingdom of Saudi Arabia (KSA)

Alammar, Saad January 2016 (has links)
In an attempt to establish more efficient and transparent governmental services, manual systems of government across the globe are being transferred to e-government systems, including the Kingdom of Saudi Arabia (KSA). However, this transformation, and especially ensuring user acceptance of e-government, poses a number of challenges. Against this backdrop, the current work examines issues that are related to information trust, professional ethics, and the risks incurred in embracing an e-government. This was carried out based on three Saudi Arabian organisations namely the Ministry of Interior; the Ministry of Communication and Information Technology; and King Abdul-Aziz City for Science and Technology. Qualitative methods was adopted for both data collection and analysis based on semi-structured interviews and questionnaires. The data were analysed using thematic analysis to establish perceptions and behavioural patterns of e-government systems among both government officials and general users. A technological gap was identified as the core impediment to widespread implementation and user acceptance of e-government in KSA. It was established that governmental success in ensuring the system is resilient against data loss and hacking, and habitual adoption of checking mechanisms, can lead towards improved implementation of e-government, along with its utilisation throughout KSA. This research contributes a research model, informed by institutional theory, of factors affecting the adoption of e-government from both employees and citizens’ perspectives (as evident within KSA). It responds to calls from other Information Systems researchers to study e-government by conducting an in-depth field investigation using qualitative research. In doing so, it addresses issues related to information trust, professional ethics and risk in e-government implementation.
30

Can environmental citizenship be enhanced through social media? : a case study of engagement in a UK university

Pianosi, Monica January 2017 (has links)
The research presented in this thesis focuses around the question: “can social media tools be used effectively to foster a participatory process that increases environmental citizenship and promote pro-environmental behaviour-change?”. The research aims to understand the role of staff and students in the socio-technical system that influences an institution’s environmental impact. Users need not to be educated, but empowered in order to be able to take decisions that would reduce the environmental impact of their institutions. Therefore a participatory process is suggested as the right tool to nurture environmental citizens, who will be able to take ‘right’ and ‘good’ decisions about their pro-environmental actions. In the last years, social media have emerged as a worldwide phenomenon. But alongside the grand claims of a social media inspired ‘revolution’ lie more nuanced questions around the role of digital tools in ‘every day’ contexts, and whether or not they are facilitating a cultural change or merely adding to the noise of modern life. The thesis contributes to the debate through presenting findings from an action research study at an East Midlands University in which a case study approach was implemented to explore the potentialities offered by participating in decision-making regarding pro-environmental issues in the institutional context, as they are mediated by social media. To generate behaviour-change the two correlated theories of public engagement and environmental citizenship were tested. Findings indicate that behaviour change and enhanced environmental citizenship are achievable through participation using social media, as several interviewees reported a change or a reinforcement of already existing pro-environmental behaviours as a consequence of the campaign. However, the reported changes were minor and it is difficult to advocate that they could noticeably contribute to the requested reduction targets on carbon emission from behaviour-change of the HE sector.

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