BCIT Citations Collection | BCIT Institutional Repository

BCIT Citations Collection

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Determination of β-N-methylamino-L-alanine, N-(2-aminoethyl)glycine, and 2,4-diaminobutyric acid in food products containing cyanobacteria by ultra-performance liquid chromatography and tandem mass spectrometry
A single-laboratory validation study was completed for the determination of β-N-methylamino-L-alanine (BMAA), N-(2-aminoethyl)glycine (AEG), and 2,4-diaminobutyric acid (DAB) in bulk natural health product supplements purchased from a health food store in Canada. BMAA and its isomers were extracted with acid hydrolysis to free analytes from protein association. Acid was removed with the residue evaporated to dryness and reconstituted with derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ-Fluor). Chromatographic separation and detection were achieved using RP ultra-performance LC coupled to a tandem mass spectrometer operated in multiple reaction monitoring mode. Data from biological samples were evaluated for precision and accuracy across different days to ensure repeatability. Accuracy was assessed by spike recovery of biological samples using varying amino acid concentrations, with an average recovery across all samples of 108.6%. The analytical range was found to be 764-0.746 ng/mL prior to derivatization, thereby providing a linear range compatible with potentially widely varying analyte concentrations in commercial health food products. Both the U. S. Food and Drug Administration (FDA) and U. S. Pharmacopeia definitions were evaluated for determining method limits, with the FDA approach found to be most suitable having an LOD of 0.187 ng/mL and LLOQ of 0.746 ng/mL. BMAA in the collected specimens was detected at concentrations lower than 1 μg/g, while AEG and DAB were found at concentrations as high as 100 μg/g. Finding these analytes, even at low concentrations, has potential public health significance and suggests a need to screen such products prior to distribution. The method described provides a rapid, accurate, and precise method to facilitate that screening process., Peer-reviewed article, Published. Received April 15, 2015; Accepted by SG June 22, 2015.
Developing safe fall strategies for lower limb exoskeletons
Proceedings of the 2017 International Conference on Rehabilitation Robotics (ICORR) QEII Centre, London, UK, July 17-20, 2017. One of the main challenges in the use of a powered lower limb exoskeleton (LLE) is to ensure that balance is maintained throughout the operation of the device. Since no control strategy has yet been implemented that prevents falls in the case of a loss of balance, head or other serious injuries may occur during independent use of LLEs in the event of a fall. These safety concerns limit LLEs in the community to supervised use only. Using the backward fall as a model, we used optimization techniques to develop safe fall control strategies in order to avoid head impact and mitigate the impact velocity of the hips. From available human biomechanics data, we first developed an optimization methodology to study falls of healthy people. The results showed similar kinematic and dynamic characteristics to findings of previous studies on real-life human falls. Second, we extended the optimization methodology to include characteristics of a hypothetical LLE and to generate optimal joint trajectories and optimal torque profiles for the fall duration. The results revealed that by applying the optimal fall strategy, the severity of a simulated fall was minimized compared to when the device fell with locked joints (i.e., how currently used exoskeletons fall): head impact was avoided and hip impact velocity was reduced by more than 50%., Conference paper, Published.
Development and evaluation of a compliance-independent pressure transducer for biomedical applications
Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society, Montreal, Quebec, Canada, on 20-23 Sept. 1995. The measurement of pressure at a device/tissue interface is desirable in many biomedical engineering applications such as tourniquets and mammography in order to optimize the design or performance of the device. Testing of a selection of existing interface transducers has demonstrated that many are dependent on device and tissue compliance. Such a transducer is only useful in an application where it has been calibrated for specific device/tissue compliance combinations. To overcome this limitation the authors have developed an interface pressure transducer whose output signal is not affected by changes in interface compliance. This enables the transducer to quantitatively measure pressure in many applications without the need to calibrate the transducer for varying compliance conditions. The signal from such a transducer could be incorporated into a control system to measure and control the pressure applied by a mammography machine to the breast., Conference paper, Published.
Development and evaluation of an affordable lift device to reduce musculo-skeletal injuries among home support workers
Home support workers (HSWs) work in clients’ homes assisting with rehabilitation and activities of daily living. Like all health-care professionals, HSWs are at an increased risk for developing back injuries. Lift devices have been shown to reduce injuries to the worker. Presently, there are few lifting devices for home use that cost under $4000 CDN. Our study involved designing a safe and affordable lift device (retail cost under $2000 CDN) to be used by HSWs in the home and evaluating it in a typical bathroom. Thirty-eight HSWs and three seniors evaluated the BCIT lift, a commercially available lift (BHM Medical Inc.) and the manual method of transfer and lift. Results indicated that the BCIT lift was an improvement over the manual method of transferring, and approximated the more expensive, automatic lift in terms of perceived exertion, ease of use and safety. Feedback provided to the researchers has been incorporated into a new, ergonomically sound and marketable lift device., Peer-reviewed article, Published. Received 1 February 2003, Revised 27 January 2004, Accepted 23 February 2004, Available online 6 May 2004.
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.
Development and pilot testing of a kneeling ultralight wheelchair design
Proceedings of 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, Italy, Aug 25-29 2015. "Dynamic wheeled mobility" offers "on the fly" seating adjustments for wheelchair users such that various activities performed throughout the day can be matched by an appropriate seat position. While this has benefits for user participation and health, the added weight in existing dynamic wheelchairs may impact the user's ability to transport the frame, e.g. into cars. Other dynamic features to enable more participation avenues are also desirable. This paper outlines the development of a "kneeling" ultralight wheelchair design that offers dynamic wheeled mobility functionality at a weight that is comparable to many existing ultralight wheelchairs. In addition, the wheelchair's kneeling function allows a lowered seat position to facilitate low-to-the-ground tasks such as floor transfers and other activities where sustained low level reaching may be required (e.g. playing with children, changing a tire, etc.). This paper also describes the development and pilot testing of an end user evaluation protocol designed to validate the wheelchair's functionality and performance. Successful realization and commercialization of the technology would offer a novel product choice for people with mobility disabilities, and that may support daily activities, health, improved quality of life, and greater participation in the community., Conference paper, Published.
Development of a lightweight low-carbon footprint concrete containing recycled waste materials
Use of any recycled material helps to maintain a greener environment by keeping waste materials out of the landfills. Recycling practices also can decrease the environmental and economical impact of manufacturing the materials from virgin resources, which reduces the overall carbon footprint of industrial materials and processes. This study examined the use of waste materials such as crushed glass, ground tire rubber, and recycled aggregate in concrete. Compressive strength and elastic modulus were the primary parameters of interest. Results demonstrated that ground tire rubber introduced significant amounts of air into the mix and adversely affected the strength. The introduction of a defoamer was able to successfully remove part of the excess air from the mix, but the proportional strength improvements were not noted implying that air left in the defoamed mixture had undesirable characteristics. Freeze-thaw tests were next performed to understand the nature of air in the defoamed mixtures, and results demonstrated that this air is not helpful in resisting freeze-thaw resistance either. Overall, while lightweight, low-carbon footprint concrete materials seem possible from recycled materials, significant further optimization remains possible., Peer-reviewed article, Published. Received 4 April 2011; Revised 27 July 2011; Accepted 27 July 2011.
Development of a micromachined pressure transducer for biomedical device/tissue interfaces
Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, Calgary, Alberta on 26-29 May 1996. In many medical situations, the need for measuring the pressure applied to a tissue quickly and accurately is crucial. Most conventional devices do not measure the actual pressure applied to the tissue because they do not compensate for the tissue or device compliance characteristics and need to be calibrated for each measurement environment. Neuromuscular damage may occur if too much pressure is applied to a tissue for an extended period of time in applications such as tourniquet systems. Incorrect diagnosis may occur if too little pressure is applied in applications such as mammography units. A compliance-independent pressure transducer has other biomedical applications in surgical retraction devices and prosthetic sockets. To eliminate the compliance problem, a pressure transducer was developed using bulk micromachining technology., Conference paper, Published.
Development of an integrated staircase lift for home access
Purpose: Stairways into buildings present a significant environmental barrier for those with mobility impairments. A number of home access solutions that allow users to safely enter and exit the home exist; however, these all have some limitations. The purpose of this work was to develop a novel, inclusive home access solution that integrates a staircase and a lift into one device. Method: We developed an integrated staircase lift following a structured protocol with stakeholders providing feedback at various stages in the design process, consistent with rehabilitation engineering design methods. Results: A novel home access device was developed. The integrated staircase-lift has the following features: inclusivity, by a design that provides an option for either use of stairs or a lift; constant availability, with a lift platform always ready for use on either level; and potential aesthetic advantages when integrating the device into an existing home. The potential also exists for emergency descent during a power outage, and self-powered versions. Conclusions: By engaging stakeholders in a user-centred design process, we were able to gain insight into the limitations of existing home access solutions and get specific feedback on our lift concept. This information strengthened the development of a novel home access device., Peer-reviewed article, Published. Article first published online: July 16, 2015; Issue published: October 26, 2015.
The development of an ultralight wheelchair with dynamic seating
Proceedings of the Rehabilitation Engineering and Assistive Technology Society of North America Annual Conference 2011. The Elevation™ wheelchair was recently developed and introduced to the market as an alternative to conventional ultralight rigid wheelchairs normally used by paraplegics and others with disabilities necessitating the daily use of a manual wheelchair. The Elevation wheelchair provides independent user-adjustable seat positioning during normal usage. Elevation allows the user to quickly and easily adjust in real-time the seat height, as well as backrest recline angle, all in a manual ultralight rigid wheelchair form factor. This allows for dynamic seat positioning to suit the tasks and comfort of users throughout their daily activities. The rationale for and user-driven development of the Elevation wheelchair is summarized here., Conference paper, Published.
The dogs of war
This paper presents a two stage model of negligence and legal action. In the first stage the defendant decides on the level of due care to take while carrying out an action or activity. In the second stage an accident has occurred and the plaintiff brings suit. Lawyers (agents) invest in actions that are designed to increase the probability of success on behalf of their respective clients. First we present the symmetric casewhere all decisions on investment in legal services occur ex-post (after an accident has occured). We then look as the case where the potential injurer pre-commits to a level of legal services ex-ante (prior to an accident) and analyze the effect that pre-commitment in legal services has on the stage one choice of care. We then present a case study from the field of labour relations where strategic pre-commitment is used to influence the settlement of grievances. The grievance process in labour relations parallel civil litigation and a grievance can be viewed as equivalent to either a tort or a breach of contract; depending on the type of grievance., Essay, Published.
Dual organizational structures in franchising
This paper extends the work of Mathewson and Winter (1985) in the field of franchising. Given the hypothesis that a franchise contract ensures quality compliance at a lower cost relative to alternative organizational structures, the existence of dual organizational structures within the same franchise chain is inadequately explained. This paper extends the basic model of Mathewson and Winter into a spatial framework, demonstrating that nonconvexities in monitoring costs will produce dual organizational structures within the same chain., Essay, Published.
Dynamic plan management in the context of a recognized air picture
This document surveys existing literature on dynamic plan management and describes the development of a prototype Air Force plan management system. The literature survey presents short summaries of a wide range of research papers, as well as a synthesis and analysis of existing approaches. The detailed comparison of existing approaches is used to formulate a specific methodology for the development of software for plan representation, plan forecasting/projection, plan analysis/evaluation and plan monitoring. The proposed methodology involves the development of a precise ontology of plan elements for plan representation. This representation removes ambiguity in the description of plans, facilitates automated analysis of plans, and also permits several different approaches to plan visualization. The implemented prototype software defines an ontology that provides a suitable internal representation of plans, along with basic plan validation capabilities. It also provides a map-based graphical user interface to visualize plans. The use of the software is demonstrated in the context of a combat search and rescue vignette. The findings conclude that the prototype demonstrates the overall utility of the approach, although further development is required to provide more detailed analysis, as well as additional visualization methods., Research report, Published.
Dynamic regulation of growing domains for elongating and branching morphogenesis in plants
With their continuous growth, understanding how plant shapes form is fundamentally linked to understanding how growth rates are controlled across different regions of the plant. Much of a plant's architecture is generated in shoots and roots, where fast growth in tips contrasts with slow growth in supporting stalks. Shapes can be determined by where the boundaries between fast- and slow-growing regions are positioned, determining whether tips elongate, branch, or cease to grow. Across plants, there is a diversity in the cell wall chemistry through which growth operates. However, prototypical morphologies, such as tip growth and branching, suggest there are common dynamic constraints in localizing chemical growth catalysts. We have used Turing-type reaction-diffusion mechanisms to model this spatial localization and the resulting growth trajectories, characterizing the chemistry-growth feedback necessary for maintaining tip growth and for inducing branching. The mechanism defining the boundaries between fast- and slow-growing regions not only affects tip shape, it must be able to form new boundaries when the pattern-forming dynamics break symmetry, for instance in the branching of a tip. In previous work, we used an arbitrary concentration threshold to switch between two dynamic regimes of the growth catalyst in order to define growth boundaries. Here, we present a chemical dynamic basis for this threshold, in which feedback between two pattern-forming mechanisms controls the extent of the regions in which fast growth occurs. This provides a general self-contained mechanism for growth control in plant morphogenesis (not relying on external cues) which can account for both simple tip extension and symmetry-breaking branching phenomena., Peer-reviewed article, Published. Received 7 December 2011, Revised 6 March 2012, Accepted 21 March 2012, Available online 28 March 2012.
Dynamic wheelchair seating positions impact cardiovascular function after spinal cord injury
Innovative wheelchairs allow individuals to change position easily for comfort and social situations. While these wheelchairs are beneficial in multiple ways, the effects of position changes on blood pressure might exacerbate hypotension and cerebral hypoperfusion, particularly in those with spinal cord injury (SCI) who can have injury to autonomic nerves that regulate cardiovascular control. Conversely, cardiovascular benefits may be obtained with lowered seating. Here we investigate the effect of moderate changes in wheelchair position on orthostatic cardiovascular and cerebrovascular reflex control.Nineteen individuals with SCI and ten neurologically-intact controls were tested in supine and seated positions (neutral, lowered, and elevated) in the Elevation™ wheelchair. Participants with SCI were stratified into two groups by the severity of injury to cardiovascular autonomic pathways. Beat-to-beat blood pressure, heart rate and middle cerebral artery blood flow velocity (MCAv) were recorded non-invasively.Supine blood pressure and MCAv were reduced in individuals with lesions to autonomic pathways, and declined further with standard seating compared to those with preserved autonomic control. Movement to the elevated position triggered pronounced blood pressure and MCAv falls in those with autonomic lesions, with minimum values significantly reduced compared to the seated and lowered positions. The cumulative duration spent below supine blood pressure was greatest in this group. Lowered seating bolstered blood pressure in those with lesions to autonomic pathways.Integrity of the autonomic nervous system is an important variable that affects cardiovascular responses to orthostatic stress and should be considered when individuals with SCI or autonomic dysfunction are selecting wheelchairs.This work was supported in part by the Heart and Stroke Foundation of British Columbia and the Yukon (V.E.C)., Peer-reviewed article, Published. Received: December 14, 2016 ; Accepted: June 12, 2017 ; Published: June 30, 2017
Dynamic wheeled mobility
31st International Seating Symposium, Nashville, TN, February 26-28, 2015. The prevalence of upper limb pain in full-time manual wheelchair users living with SCI is estimated to be anywhere from 30-70%. For those who rely on an ultralight wheelchair for their day-to-day function, the consequences can be significant and will impact more than just their mobility. Since they were published in 2005, the Clinical Practice Guidelines for Preservation of Upper Limb Function Following Spinal Cord Injury (CPG’s) have served as a valuable evidence-based resource for clinicians and seating/wheeled mobility professionals who work with the SCI population. The recommendations related to wheelchair use are based on extensive research that has examined the effects of the wheelchair’s configuration and the user’s propulsion technique on upper limb function. The recommendations focus on three general areas: Ergonomics, Equipment Selection, and Training., Conference paper, Published.

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