BCIT Citations Collection | BCIT Institutional Repository

BCIT Citations Collection

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Collection of published works from BCIT researchers, faculty, and instructors.

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Measurement of the sound absorption characteristics of vegetative roofs
Vegetative roofs have the potential to provide excellent external/internal sound isolation due to their high mass, low stiffness and their damping effect, and to provide a high level of sound absorption due to the low impedance of the vegetative substrate layer. The acoustical characteristics of vegetative roofs provide ecological contributions to the urban environment through a reduction of noise pollution from aircraft, elevated transit systems, and industrial noise. Vegetative roofs can reduce sound transmission into the interior of buildings, contributing to improved room acoustics through a reduction in noise and hence a reduction in distraction and stress (Connelly & Hodgson 2008). Through surface absorption, vegetative roofs will affect the propagation and build-up of positive and negative sounds and reduce reverberation in enclosed rooftop areas, altering the quality of the soundscape and the habitability of rooftops. Vegetative roofs can be comprised of various material layers: root barrier, water reservoir/drainage layer, filter fabric, substrates and plants. The layer thought to have the most significant effect on the vegetative roof’s acoustical characteristics is the layer of the vegetation and substrate. The vegetative substrate is complex to characterize; it varies in terms of the depth of substrate, the substrate constituents and physical properties, the plant’s aerial biomass and root structure, as well as the dynamic in-situ microclimatic and conditions which vary over season and time., Article, Published.
Measuring gene expression noise in early drosophila embryos
Proceedings of the International Conference on Computational Science, ICCS 2012. In recent years the analysis of noise in gene expression has widely attracted the attention of experimentalists and theoreticians. Experimentally, the approaches based on in vivo fluorescent reporters in single cells appear to be straightforward and effective tools for bacteria and yeast. However, transferring these approaches to multicellular organisms presents many methodological problems. Here we describe our approach to measure between-nucleus variability (noise) in the primary morphogenetic gradient of Bicoid (Bcd) in the precellular blastoderm stage of fruit fly (Drosophila) embryos. The approach is based on the comparison of results for fixed immunostained embryos with observations of live embryos carrying fluorescent Bcd (Bcd-GFP). We measure the noise using two-dimensional Singular Spectrum Analysis (2D SSA). We have found that the nucleus-to-nucleus noise in Bcd intensity, both for live (Bcd-GFP) and for fixed immunstained embryos, tends to be signal-independent. In addition, the character of the noise is sensitive to the nuclear masking technique used to extract quantitative intensities. Further, the method of decomposing the raw quantitative expression data into a signal (expression surface) and residual noise affects the character of the residual noise. We find that careful masking of confocal images and use of appropriate computational tools to decompose raw expression data into trend and noise makes it possible to extract and study the biological noise of gene expression., Conference paper, Published.
Mechanical properties of low-strength concrete blocks simulating construction in developing countries
Proceedings of the 12th North American Masonry Conference in Boulder, Colorado, May 17-20th, 2015. It is believed that one of the causes for unacceptably high death toll in the 2010 Haiti earthquake was due to use of low-strength hollow concrete blocks for masonry construction. After the earthquake, a team of BCIT faculty and students started to work on developing a low-cost nondestructive testing device for strength evaluation of concrete blocks which could be used in Haiti and other countries. The concept is based on the relationship between the compressive strength and the corresponding resonant frequency determined when a block is subjected to a mild impact. A simple block mould procured from Haiti was used to manufacture units with varying mix proportions typical of low-to medium-strength concrete blocks. In total, more than 70 concrete blocks and companion cylinders were made using13 different mix proportions to determine the compressive strength and other mechanical properties., Conference paper, Published.
Mid-embryo patterning and precision in Drosophila segmentation
In early development, genes are expressed in spatial patterns which later define cellular identities and tissue locations. The mechanisms of such pattern formation have been studied extensively in early Drosophila (fruit fly) embryos. The gap gene hunchback (hb) is one of the earliest genes to be expressed in anterior-posterior (AP) body segmentation. As a transcriptional regulator for a number of downstream genes, the spatial precision of hb expression can have significant effects in the development of the body plan. To investigate the factors contributing to hb precision, we used fine spatial and temporal resolution data to develop a quantitative model for the regulation of hb expression in the mid-embryo. In particular, modelling hb pattern refinement in mid nuclear cleavage cycle 14 (NC14) reveals some of the regulatory contributions of simultaneously-expressed gap genes. Matching the model to recent data from wild-type (WT) embryos and mutants of the gap gene Krüppel (Kr) indicates that a mid-embryo Hb concentration peak important in thoracic development (at parasegment 4, PS4) is regulated in a dual manner by Kr, with low Kr concentration activating hb and high Kr concentration repressing hb. The processes of gene expression (transcription, translation, transport) are intrinsically random. We used stochastic simulations to characterize the noise generated in hb expression. We find that Kr regulation can limit the positional variability of the Hb mid-embryo border. This has been recently corroborated in experimental comparisons of WT and Kr- mutant embryos. Further, Kr regulation can decrease uncertainty in mid-embryo hb expression (i.e. contribute to a smooth Hb boundary) and decrease between-copy transcriptional variability within nuclei. Since many tissue boundaries are first established by interactions between neighbouring gene expression domains, these properties of Hb-Kr dynamics to diminish the effects of intrinsic expression noise may represent a general mechanism contributing to robustness in early development., Peer-reviewed article, Published. Received: December 5, 2014; Accepted: December 15, 2014; Published: March 20, 2015.
Mitigating agricultural greenhouse gas emissions
Agriculture contributes significantly to anthropogenic greenhouse gases (GHGs), with estimates of agriculture's contribution ranging from 10% to 25% of total global GHG emissions per year. The science regarding mitigating (reducing and removing) GHGs through agriculture is conflicting and inconclusive. However, the severity and urgency of climate change and its potential effects on food security demonstrate that we must include mitigation within food system planning frameworks. In British Columbia, Canada, the provincial government has established significant GHG reduction targets for its agencies, and has called on local governments to reduce their carbon footprints through a charter and incentive, as well as through growth management legislation. At the same time, local governments, are giving increased attention to development of local/regional agri-food systems. However, GHG mitigation efforts do not yet seem to factor into local agri-food system discussions. Although frameworks for reporting agriculture GHGs exist, local government measurement of agriculture mitigation is hampered by a lack of agriculture GHG inventories, limited data availability, and the inherent variability in agriculture emissions and removals due to the dynamic nature of farm ecosystems. With the goal of informing local governments and food system planners on the importance of agriculture GHG mitigation, this paper (1) reviews the science of GHGs, (2) describes sources of agriculture GHG emissions and illustrates potential mitigation practices, (3) discusses the variability of agriculture mitigation science, (4) highlights the importance of agriculture GHG inventories, and (5) emphasizes the necessity for local agriculture mitigation strategies., Peer-reviewed article, Published. Submitted 18 April 2011 ; Revised 4 July 2011 and 1 August 2011 ; Accepted 2 September 2011 ; Published online 20 March 2012.
Mobile forensics for cloud data
Proceedings of 2016 14th Annual Conference on Privacy, Security and Trust (PST) in Auckland, New Zealand, 12-14 Dec. 2016. Forensic examinations of a mobile phone that consider only the internal memory can miss potentially vital data that is accessible from the device, but not stored locally. In this paper, we look at a forensic tool that is able to download data stored on the cloud, using credentials gleaned from device extractions. Through experimention with a variety of devices and configurations, we examine the effectiveness of the software for its stated purpose. The results suggest that we are able to obtain information from the cloud in this manner, but only under some relatively strong assumptions. Practical issues and legal considerations are discussed., Conference paper, Published.
MobiSense
Proceedings of Rehabilitation Engineering and Assistive Technology Society of North America Annual Conference 2014. Mobile devices such as phones and tablets are now ubiquitous and have become important tools in our daily lives. Our activities and behaviours are becoming increasingly coupled to these new devices with their ever improving sensor technologies. With current devices, mobility patterns and physical activity levels are particularly amenable to inference and analysis by leveraging the integration of GPS, accelerometers, and other sensors. Coupled with feedback through display screens, speakers, and vibration, mobile technology has reached a level of sophistication that it now presents as an attractive platform for assistive technology research and health-related applications. [...] The general goals of the MobiSense project are: 1) to collect mobility data in a simple to use manner; 2) to provide easily accessible summaries and analysis of daily behaviours; and 3) to enable further research and development by providing a sandbox environment for rapid prototyping and experimentation. The specific objectives of the research reported here are to leverage mobile data collection technology and centralized analysis to detail a wheelchair user's daily activity; thus, we developed a system based on Android phones, cloud computing and storage services, and custom web services., Conference paper, Published.
Modeling the evolution of gene regulatory networks for spatial patterning in embryo development
A central question in evolutionary biology concerns the transition between discrete numbers of units (e.g. vertebrate digits, arthropod segments). How do particular numbers of units, robust and characteristic for one species, evolve into another number for another species? Intermediate phases with a diversity of forms have long been theorized, but these leave little fossil or genomic data. We use evolutionary computations (EC) of a gene regulatory network (GRN) model to investigate how embryonic development is altered to create new forms. The trajectories are epochal and non-smooth, in accord with both the observed stability of species and the evolvability between forms., Peer-reviewed article, Published.
Modelling cryptographic protocols in a theory of action
Proceedings of the Ninth International Symposium on Logical Formalizations of Commonsense Reasoning, Toronto, ON, June 1-3, 2009. This paper proposes a framework for analysing cryptographic protocols by expressing message passing and possible attacks as a situation calculus theory. While cryptographic protocols are usually quite short, they are nonetheless notoriously difficult to analyse, and are subject to subtle and nonintuitive attacks. Our thesis is that in previous approaches for expressing protocols, underlying domain assumptions and capabilities of agents are left implicit. We propose a declarative specification of such assumptions and capabilities in the situation calculus. A protocol is then compiled into a sequence of actions to be executed by the principals. A successful attack is an executable plan by an intruder that compromises the stated goal of the plan. We argue that not only is a full declarative specification necessary, it is also much more flexible than previous approaches, permitting among other things interleaved runs of different protocols and participants with varying abilities., Conference paper, Published.
Modelling the effects of structural cracking on carbonation front advance into concrete
Concrete structures are almost certain to contain cracks due to different physiochemical mechanisms. The formation of cracks is sure to affect its durability by altering ion and fluid transport properties. This includes the incursion of CO2 into the structure. There presently exists no consensus on how to model the effects of structural cracking on carbonation progress within concrete structures. This paper first examines the concept of effective diffusion based on simultaneous diffusion of CO2 through sound and cracked concrete and then considers a series diffusion concept where CO2 diffuses first into the crack, and then outwards into the sound concrete. It is concluded that the effective diffusion concept is not valid for structurally cracked concrete. Instead, research efforts should be concentrated on developing a two–phase series diffusion model., Peer-reviewed article, Published.
Moisture response of sheathing board in conventional and rain-screen wall systems with shiplap cladding
Building enclosures are subjected to a random climatic loading on the exterior surface and a relatively stable indoor condition on the interior. These loadings result in a transport of heat, air, and moisture across the building enclosure. In this paper, the drying and wetting of sheathing board in two exterior walls, more specifically 2×6 in.2 wood-frame conventional (no strapping between sheathing membrane and cladding) and a rain-screen wall system (with vertical strapping), are investigated through an experimental field study. The experiment is carried out at British Columbia Institute of Technology field exposure test facility, where the test walls are exposed to the coastal climate (Vancouver weather) on the exterior and controlled indoor temperature and relative humidity conditions in the interior. The field experimental results indicate significant moisture accumulation on the exterior sheathing boards (plywood) during the Winter period. During the 9-month monitoring period from March 13 to Dec. 6, 2009, the plywood underwent a process of drying and wetting. In both the conventional and rain-screen wall systems, the plywood dried to a comparable moisture level during the Summer before the wetting process started. For the wall systems considered in this study, the plywood in the rain-screen wall has a tendency of faster drying and wetting in the Spring and Fall seasons, respectively, in comparison to the plywood in the conventional wall, which is attributed to the presence of an air gap in the rain-screen wall between the sheathing membrane and the cladding. A similar trend is observed during the monitoring period from December 7 to June 15, 2010., Peer-reviewed article, Published. Manuscript received January 14, 2010; accepted for publication August 14, 2010; published online October 2010.
Molecular targets for therapeutic intervention after spinal cord injury
In an effort to develop therapies for promoting neurological recovery after spinal cord injury, much work has been done to identify the cellular and molecular factors that control axonal regeneration within the injured central nervous system. This review summarizes the current understanding of a number of the elements within the spinal cord environment that inhibit axonal growth and outlines the factors that influence the neuron’s ability to regenerate its axon after injury. Recent insights in these areas have identified important molecular pathways that are potential targets for therapeutic intervention, raising hope for victims of spinal cord injury., Peer-reviewed article, Published.
Motivating high school girls to study computer science
This research study aims to identify design strategies, instructional models and technological tools (e.g., educational games) that can be used to motivate high school girls to pursue computer science (CS) education. Part of this study, an educational game CodeBlock intended to teach basic programming, was designed and implemented for HoloLens devices. This study evaluates to what extent participating in a coding workshop consisting of a set of coding exercises and the CodeBlock game play could increase the interest of high school girls in CS. The workshop is conducted by undergraduate students who were involved in the design and implementation of the game, which has an additional benefit of exposing young girls to technologies implemented by post-secondary students, thus increasing the chances they will pursue post-secondary education in CS related fields., Not peer reviewed, Conference proceedings
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.
New approaches to designing genes by evolution in the computer
The field of Evolutionary Computation (EC) has been inspired by ideas from the classical theory of biological evolution, with, in particular, the components of a population from which reproductive parents are chosen, a reproductive protocol, a method for altering the genetic information of offspring, and a means for testing the fitness of offspring in order to include them in the population. In turn, impressive progress in EC - understanding the reasons for efficiencies in evolutionary searches - has begun to influence scientific work in the field of molecular evolution and in the modeling of biological evolution (Stemmer, 1994a,b; van Nimwegen et al. 1997; 1999; Crutchfield & van Nimwegen, 2001). In this chapter, we will discuss how developments in EC, particularly in the area of crossover operators for Genetic Algorithms (GA), provide new understanding of evolutionary search efficiencies, and the impacts this can have for biological molecular evolution, including directed evolution in the test tube. GA approaches have five particular elements: encoding (the ‘chromosome’); a population; a method for selecting parents and making a child chromosome from the parents' chromosomes; a method for altering the child’s chromosomes (mutation and crossover/recombination); criteria for fitness; and rules, based on fitness, by which offspring are included into the population (and parents retained). We will discuss our work and others’ on each of these aspects, but our focus is on the substantial efficiencies that can be found in the alteration of the child chromosome step. For this, we take inspiration from real biological reproduction mechanisms., Book chapter, Published.
Noise in the segmentation gene network of Drosophila, with implications for mechanisms of body axis specification
Specification of the anteroposterior (head-to-tail) axis in the fruit fly Drosophila melanogaster is one of the best understood examples of embryonic pattern formation, at the genetic level. A network of some 14 segmentation genes controls protein expression in narrow domains which are the first manifestation of the segments of the insect body. Work in the New York lab has led to a databank of more than 3300 confocal microscope images, quantifying protein expression for the segmentation genes, over a series of times during which protein pattern is developing (http://flyex.ams.sunysb.edu/FlyEx/). Quantification of the variability in expression evident in this data (both between embryos and within single embryos) allows us to determine error propagation in segmentation signalling. The maternal signal to the egg is highly variable, with noise levels more than several times those seen for expression of downstream genes. This implies that error suppression is active in the embryonic patterning mechanism. Error suppression is not possible with the favoured mechanism of local concentration gradient reading for positional specification. We discuss possible patterning mechanisms which do reliably filter input noise., Peer-reviewed article, Published.

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