BCIT Citations Collection
Collection of published works from BCIT researchers, faculty, and instructors.
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- The effect of fiber characteristics on hydrolysis and cellulase accessibility to softwood substrates
- The effect of gross fiber characteristics on enzyme accessibility and hydrolysis of Douglas fir kraft pulp substrates was investigated. The average fiber size and coarseness of the substrate had a significant effect on the enzyme adsorption capacity. This was primarily due to the increased specific surface area of small fibers and fines. The observed adsorption capacities were in agreement with the hydrolysis rates and yields because the substrates with the lower average fiber size were hydrolyzed both at a faster rate and more completely. The observed changes in fiber-length distribution and fiber coarseness suggested that the effect of fiber size was most influential during the initial stages of hydrolysis. The small fibers and fines present in heterogeneous, lignocellulosic substrates were hydrolyzed rapidly, yielding a high initial rate of hydrolysis., Peer-reviewed article, Published. Received 27 January 1999; Revised 10 June 1999; Accepted 15 June 1999; Available online 1 November 1999.
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- The effects of gene recruitment on the evolvability and robustness of pattern-forming gene networks
- Gene recruitment or co-option is defined as the placement of a new gene under a foreign regulatory system. Such re-arrangement of pre-existing regulatory networks can lead to an increase in genomic complexity. This reorganization is recognized as a major driving force in evolution. We simulated the evolution of gene networks by means of the Genetic Algorithms (GA) technique. We used standard GA methods of point mutation and multi-point crossover, as well as our own operators for introducing or withdrawing new genes on the network. The starting point for our computer evolutionary experiments was a 4-gene dynamic model representing the real genetic network controlling segmentation in the fruit fly Drosophila. Model output was fit to experimentally observed gene expression patterns in the early fly embryo. We compared this to output for networks with more and less genes, and with variation in maternal regulatory input. We found that the mutation operator, together with the gene introduction procedure, was sufficient for recruiting new genes into pre-existing networks. Reinforcement of the evolutionary search by crossover operators facilitates this recruitment, but is not necessary. Gene recruitment causes outgrowth of an evolving network, resulting in redundancy, in the sense that the number of genes goes up, as well as the regulatory interactions on the original genes. The recruited genes can have uniform or patterned expressions, many of which recapitulate gene patterns seen in flies, including genes which are not explicitly put in our model. Recruitment of new genes can affect the evolvability of networks (in general, their ability to produce the variation to facilitate adaptive evolution). We see this in particular with a 2-gene subnetwork. To study robustness, we have subjected the networks to experimental levels of variability in maternal regulatory patterns. The majority of networks are not robust to these perturbations. However, a significant subset of the networks do display very high robustness. Within these networks, we find a variety of outcomes, with independent control of different gene expression boundaries. Increase in the number and connectivity of genes (redundancy) does not appear to correlate with robustness. Indeed, removal of recruited genes tends to give a worse fit to data than the original network; new genes are not freely disposable once they acquire functions in the network., Book chapter, Published.
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- 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.
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- The effects of structural cracking on carbonation progress in reinforced concrete
- Proceedings of 3rd International Conference on the Durability of Concrete Structures, 17-19 September 2012, Queen’s University Belfast. There is nearly unanimous consensus among scientists that increasing greenhouse gas emissions, including CO2 generated by human activity, are affecting the Earth’s climate. One essential area which will be affected is the durability of concrete infrastructure. Past research indicates that climate change will exacerbate the rate of carbonation of reinforced concrete structures, potentially leading to premature corrosion of embedded rebar. Cracking of the covering concrete could further increase carbonation rates, but the extent of the increase is unknown. The purpose of this study is to investigate the carbonation of cracked concrete under accelerated test conditions, and to numerically model the movement of the carbonation front in cracked concrete using the concept of effective diffusivity. It was found that the presence of a deep structural crack in a concrete specimen greatly increases the rate of carbonation, possibly leading to premature, localized corrosion within the specimen. The effect of cracks is likely to be much greater than the effect of increased temperatures and increased atmospheric CO2 concentrations. As a result, emphasis must be placed on designing durable infrastructure and following proper maintenance practices so that cracks are less likely to form, thereby extending the longevity of the structure in question., Conference paper, Published.
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- The impact of spinal cord injury on sexual function
- Study Design: Secure, web-based survey. Objectives: Obtain information from the spinal cord injured (SCI) population regarding sexual dysfunctions, with the aim of developing new basic science and clinical research and eventual therapies targeting these issues. Setting: Worldwide web. Methods: Individuals 18 years or older living with SCI. Participants obtained a pass-code to enter a secure website and answered survey questions. A total of 286 subjects completed the survey. Results: The majority of participants stated that their SCI altered their sexual sense of self and that improving their sexual function would improve their quality of life (QoL). The primary reason for pursuing sexual activity was for intimacy need, not fertility. Bladder and bowel concerns during sexual activity were not strong enough to deter the majority of the population from engaging in sexual activity. However, in the subset of individuals concerned about bladder and/or bowel incontinence during sexual activity, this was a highly significant issue. In addition, the occurrence of autonomic dysreflexia (AD) during typical bladder or bowel care was a significant variable predicting the occurrence and distress of AD during sexual activity. Conclusion: Sexual function and its resultant impact on QoL is a major issue to an overwhelming majority of people living with SCI. This certainly constitutes the need for expanding research in multiple aspects to develop future therapeutic interventions for sexual health and SCI., Peer-reviewed article, Published.
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- The impact of step targeting during normal gait for persons wearing either a SACH or a dynamic-response foot
- This study compared dynamic-response feet to SACH feet with respect to factors influencing unilateral transtibial amputee balance and ability to adapt to variable terrains. This was done by measuring ground reaction forces for 30% perturbations of step length during level walking. These perturbations resulted in either a lengthening or a shortening of one step length by 30% of the normal step length. Subjects walked along a 12 metre walkway and across two flush mounter force platforms while forces were recorded for both feet. Three experimental conditions were completed with each foot type: normal step length, short step length (reduced by 30% from normal), and long step length (increased by 30% from normal)., Research report, Published.
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- The importance of method selection in determining product integrity for nutrition research
- The American Herbal Products Association estimates that there as many as 3000 plant species in commerce. The FDA estimates that there are about 85,000 dietary supplement products in the marketplace. The pace of product innovation far exceeds that of analytical methods development and validation, with new ingredients, matrixes, and combinations resulting in an analytical community that has been unable to keep up. This has led to a lack of validated analytical methods for dietary supplements and to inappropriate method selection where methods do exist. Only after rigorous validation procedures to ensure that methods are fit for purpose should they be used in a routine setting to verify product authenticity and quality. By following systematic procedures and establishing performance requirements for analytical methods before method development and validation, methods can be developed that are both valid and fit for purpose. This review summarizes advances in method selection, development, and validation regarding herbal supplement analysis and provides several documented examples of inappropriate method selection and application., Peer-reviewed article, Published.
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- 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.
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- The marihuana indoor production calculator
- The clandestine nature of illicit indoor marihuana production makes is difficult to measure the true extent of marihuana cultivation in a given policing jurisdiction. As a result, law enforcement must rely on estimations in order to understand the scale of the problem in terms of the number of growing operations, the number of growers, or the monetary value of the industry. This article describes an online estimation tool that was developed to aid law enforcement in the estimation of the annual production, domestic sale, exportation, and total value of marihuana produced in commercial growing operations within a given jurisdiction., Research article, Published.
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- The need for an accurate indoor humidity model for building envelope performance analysis
- Proceedings of the Fourth International Building Physics Conference: Energy Efficiency and New Approaches: 15 June 2009, Istanbul, Turkey. The performance of a building envelope component is usually assessed based on the moisture analysis of individual components (such as cladding, sheathing board and/or drywall) for their drying potentials and likelihood of occurrence of problems associated with high moisture accumulation. In the current building envelope simulation practice, the indoor and outdoor boundary conditions are predefined in the context of the local weather data. The indoor boundary conditions are usually assumed to be constant throughout the simulation period, or two sets of values for the summer and winter periods are assumed. Although the outdoor boundary condition (weather data) is independent of the hygrothermal condition of the envelope, the indoor condition is highly influenced by the building enclosure and occupants? activities. Consequently, simplistic assumptions of indoor humidity profiles, which ignore the dynamic coupling of the indoor environment and building enclosure and represented with a set of empirical values, may lead to inaccurate conclusion about the moisture performance of the building enclosure. In this paper, the effects of indoor humidity profiles that are assumed during moisture performance evaluation of exterior building envelope component are analyzed. The indoor humidity profiles, which are considered in the study, are based on measured and simulated data of a real house. Indoor humidity models including a whole building hygrothermal model are used to generate four indoor humidity profiles. The hygrothermal dynamic responses of the building envelope component with respect to the various cases of indoor humidity assumptions are simulated and analyzed. The simulation results suggest that it is important to have more accurate indoor boundary conditions data, which are based on measurement or whole building hygrothermal modelling, to satisfactorily asses the moisture performance of a building enclosure and potential occupants health problems related to mould growth., Peer reviewed article, Published.
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- The path of the smart grid
- Exciting yet challenging times lie ahead. The electrical power industry is undergoing rapid change. The rising cost of energy, the mass electrification of everyday life, and climate change are the major drivers that will determine the speed at which such transformations will occur. Regardless of how quickly various utilities embrace smart grid concepts, technologies, and systems, they all agree onthe inevitability of this massive transformation. It is a move that will not only affect their business processes but also their organization and technologies., Final article published
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- The rise of living architecture
- "Gives voice to more than fifty extraordinary people who are currently engaged with this transformation. These individuals form a diverse community that cuts across professional disciplines, cultural, linguistic and gergraphical boundaries. They share a belief that they can make a difference through their varied efforts to expand living architectural approaches that result in biophilic, restorative buildings and healthier and more resilient communities." Profiles more than 50 of the hundreds of leaders that have created the base and molded the foundation of living architecture., Book, Published.