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BCIT Citations Collection

Development and evaluation of an interface pressure transducer for biomedical applications
The measurement of the interface pressure between a biomedical device and part of the human body is useful to aid in the design or improve the performance and safety of such devices. Therefore, a need exists for a transducer to measure interface pressure in these applications. The development and evaluation of an interface pressure transducer was the main goal of this research. Surgical retraction, surgical tourniquets and mammography were selected as demonstration applications for the developed transducer. These target applications were selected because they represented a wide spectrum of device and tissue characteristics and properties, and were in common use. A review of the available clinical, commercial and engineering literature identified a wide range of transducers and transducer technologies used for interface pressure measurement. The transducers included pneumatic/hydraulic, fibre-optic, strain based, capacitive and micromachined technologies. No standard method of measuring interface pressure was described and, in many cases, investigators cautioned against comparing-interface pressure measurements obtained using different measurement systems. From this review and an examination of the biomedical applications mentioned, the design criteria and optimal design specifications for an interface pressure transducer were defined. To gain a better understanding of the mechanical response of the interface between a device, transducer, and tissue to an applied loading, a preliminary finite element model was developed and studied. The model demonstrated the potential for shear stresses to develop between the transducer and interface materials. Furthermore a calibration system which simulated interface conditions was developed to evaluate both existing and developed transducers for use as interface pressure transducers. This evaluation demonstrated the lack of a transducer whose output was independent of the compliance of the interface materials. As well, an essential characteristic was identified for an effective interface pressure transducer that could be used in several applications where the interface material compliance was different. Based on the knowledge gained from the finite element analysis and existing transducer evaluation results, a novel interface pressure transducer was developed and evaluated both in the calibration system and via demonstration applications of surgical retraction and tourniquets. Under laboratory conditions in the calibration system, the transducer met many of the desired design specifications. The transducer was tested in the lab under both pneumatic and nonpneumatic tourniquet cuffs. The transducer worked well under the pneumatic cuff but required ] further development for use under the non-pneumatic cuff. The transducer was also integrated into a surgical retractor and evaluated in five clinical trials. It met many of the desired specifications for this application., Thesis, Published.
The effects of global climate change on carbonation induced corrosion of reinforced concrete structures
There is nearly unanimous consensus amongst scientists that increasing greenhouse gas emissions, including CO2 generated by human activity, are affecting the Earth‘s climate. Climate change has the potential to overwhelm existing capacities, as well as durability of concrete infrastructure. Carbonation of concrete occurs due to a reaction between atmospheric CO2 and the hydrated phases of concrete, leading to a drop in its pH and the depassivation of embedded rebar. Therefore, increases in carbonation rates of reinforced concrete structures are expected as a result of increased temperatures and CO2 concentrations, with the enhanced risk of carbonation induced corrosion likely affecting the longevity of our concrete infrastructure. This thesis considered the potential consequences of global climate change on our concrete infrastructure, with the objective being to determine if there is an increased risk of deterioration due to carbonation induced corrosion. A unique numerical model was developed to determine carbonation rates in structures, and verified through experimental tests. The model was applied to a numbers of cities in locations throughout the world to determine where structures were most vulnerable. Additionally, a number of other laboratory experiments were carried out to supplement the numerical model and provide insights as to how carbonation progress can be monitored within a structure. Using the model developed, and inputting forecasts for increases in future atmospheric CO2 concentrations and weather conditions, it was shown that for medium quality, non-pozzolonic concrete in geographic areas where carbonation induced corrosion is a concern, global climate change will affect its progress in our concrete infrastructure. We will see much higher ultimate carbonation depths in the long term. The use of non-destructive testing (NDT) methods, and structural health monitoring (SHM) techniques could be invaluable in monitoring the progress of carbonation in a structure, but the data generated by the methods and techniques used must be analyzed carefully before making any conclusions. For the NDT methods and carbonation pH sensors which were evaluated in this study, it was found that ambient test conditions had a major impact on results., Thesis, Published.
Getting serious about sustainability
One-planet living represents the per capita share of global ecosystem services that each person on Earth could use were humanity to live equitably within ecological carrying capacity. My research uses ecological footprint analysis to explore the potential for the City of Vancouver to achieve one-planet living. Specifically, I examine what reductions in per capita ecological footprint would be necessary, what policies or changes to management practices are available to the City to facilitate those reductions, and what one-planet living might “look like” if those policies and changes to urban management practices were implemented. I use 2006 data to conduct an integrated urban metabolism and ecological footprint assessment for the City in order to establish a baseline from which to estimate the necessary reductions in material and energy consumption. I develop lifestyle archetypes of societies living at a one-planet ecological footprint (both real and hypothetical) to inform estimates on how changes in diet, buildings, consumables and waste, transportation and water could achieve one-planet living in Vancouver. I also draw on examples from the international sustainable cities literature and interviews with City of Vancouver and Metro Vancouver staff and elected representatives to develop policy proposals for reducing Vancouver’s ecological footprint. Getting to one-planet living in Vancouver requires at least a 58% reduction in the per capita ecological footprint with the greatest contributions coming from reducing food waste, red meat consumption, and virtually eliminating personal motor vehicle use (shifting instead to an 86% walk, cycle and transit mode share which the City already achieves in its Downtown). The City has and can continue to influence individual and corporate choices through zoning and permitting. However, citizens would have to accept lifestyle changes pertaining to food and personal consumption to achieve the one-planet living goal. Involvement by senior governments in reducing the ecological footprint is also required. It remains to be seen whether Vancouverites, or any population accustomed to modern consumer lifestyles, will voluntarily accept and implement the changes necessary to achieve equitable sustainability as articulated by one-planet living., Thesis, Published.
The influence of AFO design on walking speed, gait symmetry, comfort and stability of hemiplegic subjects
"This thesis is submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Prosthetics and Orthotics"., Thesis, Published.
Purification and characterization of a selective growth regulator for human myelopoietic progenitor cells
A monoclonal antibody, named CAMAL-1, was raised previously in our laboratory to a common antigen of acute myeloid leukemia (CAMAL), and was shown to be highly specific in its recognition of cells from patients with acute (AML) or chronic (CML) myelogenous leukemia. CAMAL was also reported to be prognostic of disease, in that patients whose numbers of CAMAL-1 reactive cells were high, or rose over time, had poorer prognoses and shorter survival times than patients whose CAMAL values were low or decreased. This correlation between CAMAL and disease prognosis led to the discovery that CAMAL-1immunoaffinity-purified leukemic cellular lysates contained a selective growth inhibitory activity for normal myeloid progenitor cells, since the growth of CML progenitors was not inhibited. The work described in this thesis focused primarily on the purification and characterization of the myelopoietic activity present in the CAMAL preparations, and its relationship to the leukemic marker (CAMAL). Initial purifications involved CAMAL-1immunoaffinity chromatography of leukemic cellular lysates, followed by FPLC molecular size fractionation and/or preparative SDS-PAGE. The myelopoietic activity was located within a30-35 kDa molecular weight fraction (P30), and the P30 fraction was consistently found to be selective in its inhibition of normal myeloid progenitors, since the growth of CML progenitors was not inhibited but was, in fact, stimulated. Antibodies were raised to P30 and used in the subsequent purification and characterization of the myelopoietic activity. Amino acid sequence analysis of the N-terminus and P30 tryptic peptides strongly suggested that P30 belonged to the serine protease family of enzymes, and the results obtained from protease assays indicated thatP30 preparations did possess enzyme activity. Prior to the completion of P30 molecular cloning experiments, however, the cDNA sequence for azurocidin/CAP37 was reported, and its predicted amino acid sequence was found to be identical to those obtained from the P30 protein samples. Azurocidin is a proteolytically inactive serine protease homologue, normally present in neutrophilic granules. Purifiedazurocidin did not possess inhibitory activity in normal progenitor cell assays; therefore, in order to isolate the biologic activity from azurocidin and other potentially contaminating proteins, P30 preparations were fractionated by reverse phase HPLC. The rpHPLC profiles were found to be similar to those reported for neutrophilic granules; however, the myelopoietica ctivity was obtained in a single rpHPLC fraction that aligned with the front portion of the azurocidin protein peak. Two dimensional isoelectric focusing/SDS-PAGE analysis of the biologically active rpHPLC fraction confirmed that it contained azurocidin, and no additional protein species were detected. Only the earlier eluting azurocidin rpHPLC fraction mediated the myelopoietic activity, and this fraction was also enriched in the higher molecular weight isoforms of azurocidin. Therefore, it appeared that a variably glycosylated isoform of azurocidin was mediating the biologic effects on myeloid progenitor cells, and because azurocidin obtained from normal neutrophils did not possess the myelopoietic activity, we speculate that the bioactive isoform of azurocidin is present in relatively higher amounts and/or is uniquely synthesized by leukemic cells., Thesis, Published.
Strengthening of timber beams using externally-bonded sprayed fibre reinforced polymers
The use of Fibre Reinforced Polymers (FRP) has grown in popularity in the construction industry. FRP has proven useful in the retrofit of various types of structural elements. It may be used for the strengthening of beams, the seismic upgrade of walls panels, as well as the jacketing of columns to provide confinement. There exist several methods of FRP application for the case of structural retrofits. These include the application of pre-prepared FRP mats, or application of FRP via the wet lay-up process. However, a new technique developed at the University of British Columbia allows for the application of FRP in the form of a spray. Externally bonded Sprayed FRP (SFRP) is known to increase strength and energy absorption capacity of a retrofitted member as well as, or better than, FRP sheets. However, tests have primarily been carried out on concrete members only. An area of interest, into which not much research has been conducted, is the application of SFRP to timber. Timber bridges are extensively used in many parts of the world. Often due to remoteness and practical constraints, it is impossible to apply FRP sheets to retrofit these bridges. SFRP would be a much easier method of FRP application. This study looked at the application of SFRP to Douglas Fir (D.Fir) Beam specimens subjected to 3-Point Flexural Loading only. The specimens were treated with either a water based (Borocol) or oil borne (Creosote) antifungal preservative prior to being sprayed with FRP. Different combinations of adhesives/bonding agents including Hydroxymethylated Resorcinol and Polymeric Isocyanates were used to try to develop a strong bond. When considering using only chemical adhesives to obtain a proper bond between the two constituents of the composite, use of HMR is recommended for timber which is untreated or has been treated with a water borne preservative such as Borocol, while a pMDI adhesive such as AtPrime 2 is recommended for timber treated with an oil borne preservative such as Creosote. For Non Creosoted beams, adhesives did not generate as significant of a strength gain. For Creosoted beams, adhesives may be sufficient to generate significant strength gain when SFRP is applied to a beam. Considering that most structures in use would probably have been treated with a preservative similar to Creosote, in practice, AtPrime 2 or some other some sort of pMDI would probably be the adhesive of choice. Based on the results of the study, it is possible to say that the application of SFRP to retrofit/rehabilitate timber structures shows considerable promise. If a decent bond is achieved between the composite constituents, it is possible to substantially increase the ultimate flexural strength of the member, as well as drastically increase its ductility and energy absorption capacity. It is recommended that further tests be carried out using different types of loading schemes, geometrical configurations of SFRP, other types of anchorage, and development of a proper analytical model before the method is adopted for widespread use., Thesis, Published.
The tyranny of chronological age
This paper presents an analysis of a phenomenon known as "The Relative Age" effect. When assessing the innate ability (or talent) of individual children who are grouped into age cohorts, systematic errors occur due to differences in biological maturity. A structural model of a multi-period progression through levels (or grades) that employs screening and selection is developed. Through a series of simulations, impact of the relative age on the of selection process is analyzed., Thesis, Draft published.
What's stopping sustainability?
Despite understanding the need to become sustainable, and knowing some of the actions required to reach this end, barriers exist that prevent individuals, and society, from adopting actions that support sustainability. To understand what some of these barriers are, the case of Vancouver's attempt to implement the 1990 Clouds of Change recommendations has been analysed. Councillors, civic staff, Task Force on Atmospheric Change members and citizens who participated in the Task Force's public participation process were asked to identify what they perceived as the barriers to action-taking by the City to implement the recommendations. Fifty-eight people were interviewed. The barriers identified fell within three categories: Perceptual/Behavioural, Institutional/Structural and Economic/Financial. Analysis reveals how the barriers functioned, which ones were perceived as causing the greatest impediment to implementation of the recommendations, what conditions facilitated implementation of some recommendations, and suggestions regarding how some barriers may be overcome in the future. The six most commonly cited barriers were: lack of understanding about the issues, perceived lack of empowerment, competing issues, inadequate funds, fear of losing constituent support and limitation of jurisdiction. Other important barriers were: differences in perception, inappropriate structure of government (vertical), weak linkages among the policies of civic and senior levels of government and weak communication linkages between government and its constituents. Many of the barriers identified contributed to a low degree of civic participation in the City. Suggestions for improving government effectiveness, in terms of its ability to implement the Clouds of Change recommendations focussed on ways of improving civic participation among citizens. Suggestions regarding the amendment of government structures and decision-making processes are also presented., Thesis, Published.