http://hdl.handle.net/11343/159 Sun, 16 Dec 2018 14:35:52 GMT 2018-12-16T14:35:52Z http://hdl.handle.net/11343/219348 Nano-scale design of cardiovascular biomaterials Karimi, Fatemeh Cardiovascular disease is the leading cause of death worldwide. The development of blood-compatible biomaterials could relieve this burden by improving the performance of cardiovascular devices such assmall-diameter vascular grafts. An attractive strategy for improving blood compatibility of an interface is to generate biomaterials that foster a confluent and functioning endothelial cell layer. Although several strategies have been explored to improve endothelialisation, there are still no commercially available blood-compatible grafts that promotes endothelialization. The lack of a blood-compatible interface is one of the most pressing challenges in the biomaterials field. As such, additional research is required in order to develop new technologies to meet this need. The aim of this work is to design a biomaterial that promotes endothelialization by mimicking cellextracellular matrix interactions. In order to achieve this, we used two biomimetic approaches: (1)nanoclustering of cell adhesive ligands (ligand multivalency) to promote the clustering of cell receptors, especially integrin receptors, and (2) dual functionalization of materials with both integrin- and syndecan-binding ligands to engage both cell receptor types to utilise their synergistic effects. To accomplish this, we synthesized a random copolymer via reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymer was composed of methyl methacrylate and polyethylene glycol methacrylate-containing units. The polymer was functionalized with integrin- and syndecanbinding ligands. A blending technique was used to generate interfaces with ligand multivalency. Specifically, highly peptide-functionalized polymer chains were blended with non-functionalized polymers chains. Upon film casting, these generated surfaces displaying nano-scale islands of high peptide density due to the size and shape of the polymer random coils. Endothelial cells were cultured on these surfaces and their behaviours were investigated under static and flow conditions. Our results show that the biomaterials functionalized with multivalent integrin-binding ligands promote the formation of focal adhesions, improve endothelial cell adhesion, migration, and endothelialization rate compared to surfaces functionalized with random distribution of integrin-binding ligands. Additionally, the biomaterials functionalized with mixed population of multivalent integrin- and syndecan-binding ligands show additional improvement over surfaces with just multivalent integrinbinding or syndecan-binding ligands alone. Specifically, we observed synergistic improvement of endothelial cell adhesion, improved focal adhesion formation and cytoskeletal assembly, an increased rate of endothelialization, and regulation of migration speed. These surfaces also regulate a range of endothelial cell functions when the cells were exposed to laminar flow shear stress including increased spreading, larger and more abundant actin stress fibers, elongation and alignment in the direction of flow, increased capture of endothelial cells from flow, and robust attachment of cells under flow. These results demonstrate that bioengineered materials presenting nanoclusters of both integrin- and syndecan-binding ligands could be used for the development of next-generation biomedical devices, especially small-diameter vascular grafts. © 2018 Dr. Fatemeh Karimi Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/11343/219348 2018-01-01T00:00:00Z http://hdl.handle.net/11343/219347 The essence of performance on the acoustic drum kit: a study of feel Raines, Sam This practice-led research investigates and discusses the terms and applications of ‘feel’ and ‘time’ in acoustic drumming, and through various performance settings I break down and examine how these phenomena exist within my performance. Topics of this research include feel, time, groove, improvisation, pulse, liveness, and motif, all of which are looked at through the various effects they can have on performance. This dissertation includes both written and recorded documentation of my own performances, as well as drawing on sources of information such as music notation (transcriptions), sound waves, various publications, liner notes and experiential descriptions of each performance setting. The creative works presented in this research are made up of various recorded performances, which can be identified in the ‘List of Embedded Audio’. As sections of this dissertation are based on specific recordings, the relevant audio is also listed within the text. This should allow the reader to listen to each recorded performance before or after the relevant section is read. Each recorded work for this research is presented in an mp3 format. © 2018 Sam Raines Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/11343/219347 2018-01-01T00:00:00Z http://hdl.handle.net/11343/219342 An assessment of climatic and anthropogenic impacts on the hydrological system of Himayat Sagar Catchment, India Nune, Rajesh Many regions of the world face water shortages that are likely to become more severe in the future. Multiple drivers are responsible for the hydrological change in catchments and these can be exogenous (change in climate variability and mean), endogenous (anthropogenic changes in catchment characteristics) or both. Water shortages, especially streamflow and groundwater storage, lead to impacts on water users within and outside the catchment, which are typically more severe for downstream users. Both exogenous and endogenous changes can have a large impact on catchment hydrology and they need to be considered together. This research aims to understand such changes in the Himayat Sagar (HS) catchment, India, where significant reductions in streamflow and declining groundwater storage have been observed for a couple of decades. This thesis aims first, to examine different changes that have taken place in HS climate and catchment characteristics, apply statistical, conceptual and hydrological modelling approaches to relate and attribute the observed changes to the trends in both the streamflow and groundwater storage and then examine potential future changes through scenario analysis. To support that analysis a field investigation was undertaken to collect information on various catchment characteristics. An analysis of the available data showed that HS streamflow has declined at a rate of 3.6 mm/y without significant changes in rainfall, over the period 1980 to 2007. Analysis indicated that evapotranspiration from the catchment have increased significantly due to landuse change. Different approaches to estimate evaporation based on the different catchment changes were used. Evapotranspiration estimates based on well inventories suggested an increase of 7.2 mm/y, whereas changes in irrigation area combined with typical irrigation practices suggests applied water increased by 9.0 mm/y. Estimates of evapotranspiration using remote sensing data showed an increasing rate of 4.1 mm/y. Changes in surface water storage capacity and interception of various small watershed development structures have also occurred and these increased by 2 mm over 7 years. These changes have likely increased recharge while reducing the streamflow of the catchment. Overall, the expansion of agricultural irrigation area led to an increase in groundwater extractions and decrease in groundwater levels, which effected the contribution of groundwater discharge (baseflow) to streamflow of the HS catchment. The second major analysis step aimed to detangle the individual and combined impacts of HS climate and catchment changes on hydrology in the past through modelling. A coupled semi-distributed surface and groundwater model, the Modified SWAT was used to model the hydrologic impacts of changes in Himayat Sagar catchment characteristics. The model was able to predict the trends in streamflow and groundwater levels well. Simulations including various subsets of catchment changes were used to separate different impacts; notably changes in hydrological structures that aim to intercept runoff and increase recharge, changes in land use, especially irrigation expansion and changes in meteorological forcing. A reduction in average annual simulated streamflow for the validation period of 2 mm or less was found when hydrological structure changes were added into a simulation. Nearly 50% of the total amount of water harvested by the hydrologic structures ultimate contributed to simulated streamflow as baseflow from the groundwater storage. Land use change and associated water extractions led to an increase of 44 mm in simulated catchment average annual irrigation amount. Which led to a net water withdrawal of 25 mm and to a decrease in streamflow of 19 mm, primarily baseflow (15 mm). Groundwater storage declined at a rate of 5 mm/y due to land use impacts and this was offset by a net addition of 2 mm/y by hydrological structures. Overall the simulations suggest that the land use change impacts on streamflow are an order of magnitude larger than the impact of hydrological structures and about 2.5 time higher in terms of groundwater impacts. The total irrigation requirement, which is met by groundwater extraction, was completely met by recharge during the wet years. During the remainder of the time, (dry and normal years), the irrigation requirement was met from a combination of recharge and existing groundwater storage (50% during dry years and 30% during normal years). Overall this is leading to moderate and unsustainable declines in groundwater over time. Finally, to examine the relative impacts of potential future land and water management changes and climate change on the catchment hydrologic cycle and its sustainability, a scenario analysis was undertaken. Providing REgional Climates for Impacts Studies – a Regional Climate Model (PRECIS RCM) future climate data was used to analyse the impact of future climate changes on streamflow and groundwater storage of HS catchment. The water storage capacity of large village drinking water storage tanks and naturally formed lakes were assumed to increase by 50% by 2020 and then remain the same until the end of the century (2098). This reflects a program referred to as Mission Kakateeya, which started in 2015 in Telangana State to rejuvenate or desilt existing village water tanks to increase the capture of rainwater over the next five years, i.e by 2020. The irrigated area in the catchment was assumed to increase at the rate of 100 km2 for every 30 years by assuming that the government of Telangana would continue to subsidise farmers, whereas past growth rates have been higher (1990-2000: 85 km2; 2000-2010: 95 km2, an average of 90 km2). Irrigation is assumed to be supported by groundwater alone. Given that the HS catchment falls in a drought prone area of India, it was also assumed that the watershed development program would continue in the future, and therefore that the water storage capacity of small watershed structures would continue to increase at a constant rate over the study period. Capacity was assumed to increase 2km2 by 2040, 4km2 by 2070 and 1.7 km2 by 2098. During early-century, streamflow were predicted to reduce by an average of 49%, increases AEt by 20% and groundwater storage decreases by 3 m across the catchment compared to the baseline period. During mid-century, streamflow were predicted to decrease by 64%, AEt increases by 36% and groundwater storage declines by 7 m compared with the baseline period. During end-century, streamflow were predicted to decrease by 65%, AEt would increase by 45%, and groundwater storage could decrease by 10 m and stores will increase from -8 to 3 mm as compared to baseline period. The contribution of base flow to streamflow plays a key role in the future, it is observed that the base flow contribution is around 20-30% during low rainfall events and 60-70% during high rainfall events as compared with baseline period. © 2018 Dr. Rajesh Nune Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/11343/219342 2018-01-01T00:00:00Z http://hdl.handle.net/11343/219340 Investigating the functional influence of perceptual stabilisation mechanisms of small eye movements Park, So Yun Even when we stare intently at an object, our eyes are in constant motion due to small, involuntary eye movements. Despite this, we do not perceive a jittery world as the visual system is able to compensate for the motion that arises and construct a stable visual percept. The thesis explores the need for such compensatory mechanisms by combining phenomenology and psychophysics to determine whether perceptual stabilisation mechanisms can have a measurable influence on visual function.. © 2018 Dr. So Yun Park Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/11343/219340 2018-01-01T00:00:00Z