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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.

Acquisition systems for in situ monitoring of athletes and equipment in curling and snowboarding

Buckingham, Mark-Paul January 2006 (has links)
This thesis covers work conducted to develop robust sensing systems which quantify the behaviour of sporting equipment in its real environment. The data collected provides understanding of how the athlete and the equipment are performing. It has allowed further analysis into specific competitive sports, improving training methods, providing equipment performance analysis and advanced equipment selection techniques. The work has focused on snowboarding and curling, both sports are conducted in a cold, harsh environment. Literature and research into previous work on these sports is presented. This thesis presents a study of the mechanical behaviour of snowboards and show how this can be used to enhance training techniques.  Procedures for quantifying physical characteristics of a snowboard are examined. A custom built laboratory rig is used to test snowboards under controlled, repeatable conditions. Results from static and dynamic on-slope tests are presented, with reference to technical literature. The design and iteration of sensing arrangements for on-slope analysis capable are shown. Dynamic testing was performed using custom wireless and hard-wired acquisition systems. The data from static and dynamic testing are correlated with snowboarder performance and its application to current training techniques is discussed. Systems developed for snowboards were transferred to curling to develop an instrumental curling brush (<i>sweep ergometer</i>). The ergometer measured the forces and accelerations involved in sweeping. The results gathered are analysed to present statistical analysis, velocities and distances swept providing users with an individual sweeper profile. The data is the first of its kind in the world of curling, allowing repeatable accurate data for sweeping at Olympic standard. These results have led to improved training and selection techniques adopted by the British Curling team.

Investigation of a device for measurement of fracture healing in the distal radius

Cardone, Lucia January 2006 (has links)
The development of a measuring device and technique is presented to measure objectively the healing process in distal radial fractures treated with an external fixator. External fixation is advocated in stabilization of unstable fractures of the distal radius to allow a rapid and better patient recovery. Removal of the external fixator too early can result in risk of refracture or late collapse of the fracture. The measuring device developed here is used to calculate the rigidity of the new callus; this quantitative parameter can contribute to the surgeon’s decision to remove the frame. Bone structure and bone fractures are examined from a mechanical and biological perspective. Fracture treatments and healing patterns are presented with particular attention to external fixators and the environmental fracture conditions imposed by these frames. Previous studies on fracture healing (for tibial and femoral fractures) have been considered during the development of the measuring device. A fracture model has been created and used to verify the reliability of the device in laboratory testing. In-vivo testing has been performed to improve the performance of the device and protocol for using it; specifically, to produce an instrument that can be adapted to suit any external fixator geometry met on patients. A pilot study was subsequently organised and conducted to verify the usefulness and reliability of the device under clinical conditions. In order to compare directly the results from different patients, the influence of various external fixator geometries has been investigated, by a finite element (FE) analysis. The FE analysis has been validated against laboratory testing with the fracture model. Combining measurements from the device and data from the computational model (from the FE analysis), the callus rigidity is determined for patients involved in the pilot study. The trend of the calculated callus rigidity is discussed and the results are compared with the conventional clinical methods to assess fracture healing.

Investigation of a technique for assessing the flow-induced clotting of prosthetic heart valves

Martin, Aimee Jeannine January 2004 (has links)
An <i>in vitro</i> technique has been developed at Edinburgh University that uses renneted milk as a blood analogue fluid for assessing the flow-induced clotting of heart valves. There were two main objectives with the current research. The first aim was to further confirm the milk technique’s ability to simulate thrombus formation, and the second aim was to assess the impact of test conditions on <i>in vitro </i>clotting. In support of the first aim, confocal laser scanning microscopy (CLSM) was utilised to observe milk coagulation in a stagnation point flow chamber at different shear rates, for comparison with platelet deposition. Comparison of the coagulation of milk with that of whole blood was achieved by testing twelve different heart valves, representing all available valve types, in the existing heart chamber and comparing localised milk clotting with sites of reported thrombus formation. Valves were then retested in a new heart chamber, which consisted of a flexible model of the left ventricle and a straight walled aortic section, or one incorporating the sinuses of Valsalva, mounted on top. Deposition of milk in the stagnation point flow chamber was dependent on shear stress; there was a minimum shear stress for protein alignment, and a maximum shear stress above which proteins did not deposit. This compared favourably with reports of limiting shear stresses for the growth of platelet aggregates, which have also been shown to align with flow in the presence of sufficient shear forces. The milk test successfully generated clots in specific, reproducible locations on all of the rigid valves tested, and this clotting compared favourably with reported sites of thrombus formation <i>in vivo</i>. However, localised milk clot did not form on a flexible trileaflet valve prototype; it was suspected that this may have been due to the valve not functioning properly under the current test conditions. Clot development was affected by both chamber design and exposure time to rennet, the latter being significant for all valve types. Localised clotting was not observed if the valve was exposed to renneted milk in the primary stage of coagulation. Clot formation on the caged-ball valves and the monoleaflet valves appeared to be independent of the test chamber shape, but clot formation on the bileaflet valves was not; interaction of the downstream flow with the chamber wall appeared to govern clot development.

Numerical simulation of blood flow and vessel wall stresses in stenosed arteries

Li, Mingxiu January 2006 (has links)
A flow-wall coupled model is developed by externally coupling of the CFD (Computational Fluid Dynamics) package FLUENT and the FEM (Finite Element Method) package ABAQUS using a MATLAB script. This model is used to study the flow and stress field for idealised stenosed arteries. The impedance of the stenosis is estimated by an LCR model and the boundary conditions are derived from a 1D transmission line model. Studies on localized stiffness for straight and mild stenosed arteries showed that the localized stiffness has a negligible effect on the pressure, local velocity magnitude and was wall shear stress (WSS) field, but it has a significant effect on the wall motion around the diseased part. Simulations of the blood flow and wall motion (WM) for different degrees of stenosis under physiologically realistic conditions was carried out. The results showed that maximum WSS increases substantially with the increase of stenosis severity. The maximum WSS is about 10Pa for healthy arteries, it reaches 45pa for a 30% stenosis (by diameter), at which endothelial stripping may occur, and for >=50% stenoses, the maximum WSS values were greater than 100Pa. Wall motion was increasingly constrained as the degree of stenosis increased. It was constrained at the throat by 55% for the 30% stenosis, 86% for the 50% stenosis; while for the 70% stenosis, WM at the throat is negligible through the whole cycle. With the increase of the degrees of stenosis, the maximum circumferential stress varies within 20%, which is a small variation compare with the changes in WSS as the degree of stenosis increases. However, the localized stiffness and physiological axial stretch has substantial influence on the circumferential stress distributions. Maximum circumferential stress was found at the shoulders of plaques with the presence of localized stiffness and physiological axial stretch.

Brittle fracture criterion for failure prediction of notches and brazed metal-to-ceramic joints

Gerguri, Shpend January 2010 (has links)
No description available.

Studies on the response to dietary cholesterol in man

Mistry, Pramod January 1979 (has links)
No description available.

Synaptic vesicle cycling and inflammatory stimulation in central and peripheral oscillators

Smith, Jennifer January 2015 (has links)
The 24-hour or circadian rhythm regulates many aspects of behaviour, metabolism and physiology. These rhythms are orchestrated by the suprachiasmatic nucleus (SCN), however many peripheral tissues have been shown to maintain their own rhythms in vitro without SCN input. Skeletal muscle rhythmically expresses many genes, including clock genes, and this study aimed to establish whether the muscle clock is dependent on the circadian transcription-translation feedback loop, and to determine the circadian behaviour of the Flexor Digitorum Brevis (FDB) and diaphragm. By monitoring PER2 production from these tissues using the mPER2::luc mouse, it was observed that both the FDB and the diaphragm maintained their PER2 rhythms in vitro. These rhythms were similar to those observed in the SCN and other peripheral tissues; however the phase of PER2 production was altered by the time of cull. These tissues also showed similar PER2 production profiles to the SCN in Afh/Afh and Cry1-/-Cry2-/- mutant mice, indicating the diaphragm and FDB act as true peripheral oscillators and may be useful as model tissues for circadian research in muscles. Vesicle cycling plays a vital role in cell-cell communication, and the disruption of this cycle is utilised by drugs such as Dysport to abolish unwanted muscle contractions by blocking exocytosis. Dysport, Dynasore (an endocytosis blocker) and TTX (a Na+ channel blocker) were used to treat SCN and muscle cultures in vitro to assess the effect of blocking the vesicle cycle on PER2 production and determine whether vesicle cycling contributes to the circadian phenotype in muscle and neuronal tissues. Whilst Dysport had no effect on PER2 production, Dynasore abolished PER2 rhythms in the SCN, yet increased PER2 production in the diaphragm. These findings suggest that there is some interplay between vesicle cycling and the circadian rhythm, however Dysport poses no threat to the circadian system when used at clinical doses. The immune system is also under circadian control, as studies have shown that clock genes regulate cytokine production and microglia rhythmically express clock proteins. Little is known about the behaviour of microglia within the SCN throughout the day, or the effect of injury and infection on the clock itself. This study aimed to assess if there is an inflammatory input to clock function, and to determine whether microglial recruitment is under temporal control. Pathogen-associated and damage-associated molecular patterns (PAMPs and DAMPs; molecules associated with infection or injury) were used in vitro to mimic an immune challenge. And although no effect of PAMPs on PER2 expression in the SCN was observed, significant reduction of PER2 rhythms and culture survival was observed in the presence of DAMPs. SCN sections were also stained for Iba1 to determine their number within the SCN and surrounding areas. It was observed that microglial recruitment altered throughout the day, with a significant peak during the active phase. The findings within this thesis show that there is complex interaction between the circadian system and both the immune system and skeletal muscles, shedding new light on their behaviours. Dysport has also been shown to have no effect on the circadian rhythm, suggesting no detrimental effects of circadian disruption will be seen whilst using this drug. However, further study is required to establish the role of vesicle cycling within the circadian system and to fully characterise the circadian behaviour of the immune system and skeletal muscles.

The coordinated regulation of phospholipase D by ADP-ribosylation factors and their exchange factors

Ha, V. L. January 2004 (has links)
Phospholipase D (PLD) is a phospholipid hydrolyzing enzyme, the activation of which has effects on cellular events including cell growth and membrane trafficking in mammalian cells. In a reconstitution assay consisting of permeabilised HL-60 cells (human myeloid leukemic cells), experiments confirmed that members of the ADP- ribosylation factor (ARF) family proteins including ARFl and ARF6 were efficient PLD activators. However, ARFl was a stronger activator of PLD than ARF6, a result that was also found in in vitro PLD assays. Moreover, the myristoylated amino terminal ?-helix of ARF was essential for the activation of PLD. The activation of ARF is in turn regulated by a specific family of small guanine nucleotide exchange factors (GEFs) comprising ARNO, GRP-1 and cytohesin-1. The GEFs catalyze the release of bound GDP and its replacement by GTP, leading to ARF activation. Using the reconstitution assay, the PLD activation mediated by ARF was enhanced by the GEFs. However, the GEFs did not improve the stimulation of PLD by ARF in vitro. Interestingly, these GEFs activated PLD with high potency but none of the three GEFs was more potent than the others in their regulation of PLD in cell- based assays. It seems that this pattern of PLD activation does not reflect differential interactions with major phosphoinositides (PIP2 and PIP3) since these molecules bind equally well to the GEFs. Importantly, PIP2 and PIP3 increased the potency of PLD activation mediated by the coordinated actions of ARF and its exchange factors indicating the involvement of other pathways in the regulation of PLD in vivo. In particular, it emerged that PIP3 is a more potent activator of PLD than PIP2 in the presence and absence of ARF-GEFs.

Investigation into the structure of collagen in mineralizing tissues

Benton, Joanne January 1999 (has links)
The aim of the present study was to further investigate the structure of collagen in mineralized tissues. Crosslink data collected for different ages of turkey leg tendon at the edge of mineralization showed no changes in the mature crosslink levels except those associated with mineralization. The reducible crosslink levels in the small sections of tissue analysed were below detection limits. X-ray diffraction analysis of different ages of turkey leg tendon also showed no changes in the axial and lateral structure except those associated with mineralization. Studies of the mineral crystal size with age showed that the crystal size increases from 12-week-old turkey leg tendon to 44-week-old turkey leg tendon and decreases in size from 44 weeks of age to 60 weeks of age, possibly due to a resorption of the mineral with age. This data together with the crosslink analysis data on different ages of tendon indicates that there is no change in the crosslink profile accompanying the increase in size of the mineral crystal which would be expected if the growing mineral crystal distorted the collagen structure. Telopeptide organisation studies in turkey leg tendon also showed that there are no differences in the nonmineralized and mineralized portions. Again this suggests that no crosslinks are being formed with lysine residues that are not normally involved in crosslinking as a result of collagen distortion. Other studies investigating the collagen production in mineralizing and nonmineralizing portions of turkey leg tendon <I>in vivo</I> suggest that collagen is being produced at a greater rate in the mineralizing portions than in the nonmineralizing portions. An <I>in vitro</I> study of lysine hydroxylation in bone cell culture showed no changes in the crosslinking profile in cells kept in growth media.

Regulation of the cell division cycle by ubiquitin and ubiquitin-like modifications in yeast

Rumsby, Ellen Louise January 2015 (has links)
The ability of a cell to regulate its cell cycle in response to external stimuli, such as oxidative stress, is important to maintain viability by preventing damage and allowing time for repair. However, the underlying sensing and signalling mechanisms behind cell cycle regulation in response to oxidative stress remain largely unclear. Ubiquitin and ubiquitin-like (Ubl) proteins are a family of highly conserved protein modifiers with a role in many cellular processes including cell cycle regulation. The use of catalytic cysteine residues in the conjugation pathways of ubiquitin and Ubls suggest a mechanism by which these modifiers can be redox-regulated. Thus the aim of this project was to investigate the regulation of the cell division cycle by ubiquitin and Ubls in response to two conditions previously observed to lead to G1 phase cell cycle arrest in S. cerevisiae, treatment with the oxidising agent diamide and glutathione depletion. We find that in response to diamide the ubiquitin E2, Cdc34 is particularly sensitive to oxidation compared to the other E2s examined. Oxidation of Cdc34 was shown to lead to an increase in the stability of the Cdc34 substrate Sic1, coincident with G1 phase arrest. We also find that the Rub1 Ubl modifier is essential for regulation of the cell cycle in response to diamide. Interestingly, we find that Rub1 is also required to prevent budding in response to glutathione depletion. Importantly, here we reveal that SIC1 is essential to maintain viability by preventing replication-induced DNA damage following glutathione depletion. Our studies demonstrate that G1 phase cell cycle arrest in response to diamide and glutathione depletion is multifaceted, involving many of the same proteins but that these proteins are regulated differently in response to the two conditions.

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