BCIT Citations Collection | BCIT Institutional Repository

BCIT Citations Collection

Pages

Accounting for greenhouse gas emissions of materials at the urban scale-relating existing process life cycle assessment studies to urban material and waste composition
Although many cities are engaged in efforts to calculate and reduce their greenhouse gas (GHG) emissions, most are accounting for "scope one" emissions i.e., GHGs produced within urban boundaries (for example, following the protocol of the International Council for Local Environmental Initiatives). Cities should also account for the emissions associated with goods, services and materials consumed within their boundaries, "scope three" emissions. The emissions related to urban consumption patterns and choices greatly influence overall emissions that can be associated with an urban area. However, data constraints and GHG accounting complexity present challenges. In this paper we propose one approach that cities can take to measure the GHG emissions of their material consumption: the solid waste life cycle assessment (LCA) based approach. We used this approach to identify a set of materials commonly consumed within cities, and reviewed published life cycle assessment data to determine the GHG emissions associated with production of each. Our review reveals that among fourteen commonly consumed materials, textiles and aluminum are associated with the highest GHG emissions per tonne of production. Paper and plastics have relatively lower production emissions, but a potentially higher impact on overall emissions owing to their large proportions, by weight, in the consumption stream., Peer-reviewed article, Published. Received November 9th, 2012; revised December 10th, 2012; accepted January 5th, 2013.
Accounting for the ecological footprint of materials in consumer goods at the urban scale
Ecological footprint analysis (EFA) can be used by cities to account for their on-going demands on global renewable resources. To date, EFA has not been fully implemented as an urban policy and planning tool in part due to limitations of local data availability. In this paper we focus on the material consumption component of the urban ecological footprint and identify the ‘component, solid waste life cycle assessment approach’ as one that overcomes data limitations by using data many cities regularly collect: municipal, solid waste composition data which serves as a proxy for material consumption. The approach requires energy use and/or carbon dioxide emissions data from process LCA studies as well as agricultural and forest land data for calculation of a material’s ecological footprint conversion value. We reviewed the process LCA literature for twelve materials commonly consumed in cities and determined ecological footprint conversion values for each. We found a limited number of original LCA studies but were able to generate a range of values for each material. Our set of values highlights the importance for cities to identify both the quantities consumed and per unit production impacts of a material. Some materials like textiles and aluminum have high ecological footprints but make up relatively smaller proportions of urban waste streams than products like paper and diapers. Local government use of the solid waste LCA approach helps to clearly identify the ecological loads associated with the waste they manage on behalf of their residents. This direct connection can be used to communicate to citizens about stewardship, recycling and ecologically responsible consumption choices that contribute to urban sustainability., Peer-reviewed article, Published. Received: 6 February 2013 ; Revised: 13 April 2013 ; Accepted: 26 April 2013 ; Published: 2 May 2013.
Accuracy, precision, and reliability of chemical measurements in natural products research
Natural products chemistry is the discipline that lies at the heart of modern pharmacognosy. The field encompasses qualitative and quantitative analytical tools that range from spectroscopy and spectrometry to chromatography. Among other things, modern research on crude botanicals is engaged in the discovery of the phytochemical constituents necessary for therapeutic efficacy, including the synergistic effects of components of complex mixtures in the botanical matrix. In the phytomedicine field, these botanicals and their contained mixtures are considered the active pharmaceutical ingredient (API), and pharmacognosists are increasingly called upon to supplement their molecular discovery work by assisting in the development and utilization of analytical tools for assessing the quality and safety of these products. Unlike single-chemical entity APIs, botanical raw materials and their derived products are highly variable because their chemistry and morphology depend on the genotypic and phenotypic variation, geographical origin and weather exposure, harvesting practices, and processing conditions of the source material. Unless controlled, this inherent variability in the raw material stream can result in inconsistent finished products that are under-potent, over-potent, and/or contaminated. Over the decades, natural product chemists have routinely developed quantitative analytical methods for phytochemicals of interest. Quantitative methods for the determination of product quality bear the weight of regulatory scrutiny. These methods must be accurate, precise, and reproducible. Accordingly, this review discusses the principles of accuracy (relationship between experimental and true value), precision (distribution of data values), and reliability in the quantitation of phytochemicals in natural products., Peer-reviewed article, Published. Received 6 July 2010; Revised 14 September 2010; Available online 25 September 2010.
The Additional sex combs gene of Drosophila encodes a chromatin protein that binds to shared and unique Polycomb group sites on polytene chromosomes
The Additional sex combs (Asx) gene of Drosophila is a member of the Polycomb group of genes, which are required for maintenance of stable repression of homeotic and other loci. Asx is unusual among the Polycomb group because: (1) one Asx allele exhibits both anterior and posterior transformations; (2) Asx mutations enhance anterior transformations of trx mutations; (3) Asx mutations exhibit segmentation phenotypes in addition to homeotic phenotypes; (4) Asx is an Enhancer of position-effect variegation and (5) Asx displays tissue-specific derepression of target genes. Asx was cloned by transposon tagging and encodes a protein of 1668 amino acids containing an unusual cysteine cluster at the carboxy terminus. The protein is ubiquitously expressed during development. We show that Asx is required in the central nervous system to regulate Ultrabithorax. ASX binds to multiple sites on polytene chromosomes, 70% of which overlap those of Polycomb, polyhomeotic and Polycomblike, and 30% of which are unique. The differences in target site recognition may account for some of the differences in Asx phenotypes relative to other members of the Polycomb group., Peer-reviewed article, Published.
Algal morphogenesis
Semi-cell morphogenesis in unicellular desmid algae of the genus Micrasterias generates a stellar shape by repeated dichotomous branching of growing tips of the cell surface. The numerous species of the genus display variations of the branching pattern that differ markedly in number of branchings, lobe width and lobe length. We have modelled this morphogenesis, following previous work by D. M. Harrison and M. Kolar (1988), on the assumptions that patterning occurs by chemical reaction-diffusion activity within the plasma membrane, leading to morphological expression by patterned catalysis of the extension of the cell surface. The latter has been simulated in simplified form by two-dimensional computations. Our results indicate that for generation of repeated branchings and for the control of diverse species-specific shapes, the loss of patterning activity and of rapid growth in regions separating the active growing tips is an essential feature. We believe this conclusion to be much more general than the specific details of our model. We discuss the limitations of the model especially in terms of what extra features might be addressed in three-dimensional computation., Peer-reviewed article, Published.
Analysis of pattern precision shows that Drosophila segmentation develops substantial independence from gradients of maternal gene products
We analyze the relation between maternal gradients and segmentation in Drosophila, by quantifying spatial precision in protein patterns. Segmentation is first seen in the striped expression patterns of the pair-rule genes, such as even-skipped (eve). We compare positional precision between Eve and the maternal gradients of Bicoid (Bcd) and Caudal (Cad) proteins, showing that Eve position could be initially specified by the maternal protein concentrations but that these do not have the precision to specify the mature striped pattern of Eve. By using spatial trends, we avoid possible complications in measuring single boundary precision (e.g., gap gene patterns) and can follow how precision changes in time. During nuclear cleavage cycles 13 and 14, we find that Eve becomes increasingly correlated with egg length, whereas Bcd does not. This finding suggests that the change in precision is part of a separation of segmentation from an absolute spatial measure, established by the maternal gradients, to one precise in relative (percent egg length) units., Peer-reviewed article, Published.
AOAC SMPR® 2016.003
AOAC SMPRs describe the minimum recommended performance characteristics to be used during the evaluation of a method. The evaluation may be an on-site verification, a single-laboratory validation, or a multi-site collaborative study. SMPRs are written and adopted by AOAC stakeholder panels composed of representatives from the industry, regulatory organizations, contract laboratories, test kit manufacturers, and academic institutions. AOAC SMPRs are used by AOAC expert review panels in their evaluation of validation study data for method being considered for Performance Tested MethodsSM or AOAC Official Methods of AnalysisSM, and can be used as acceptance criteria for verification at user laboratories., Peer-reviewed article, Published.
Assessment of energy rating of polyurethane spray foam walls
The application of polyurethane spray foam (SPF) insulation in buildings provides a durable and efficient thermal barrier. The industry is also promoting the SPF as an effective air barrier system in addition to its thermal insulation characteristics. In an effort to address these issues, a consortium of SPF manufacturers and contractors, jointly with the National Research Council of Canada’s Institute for Research in Construction conducted an extensive research project to assess the thermal and air leakage characteristics of SPF walls as well as conventional wall assemblies. The objective is to develop analytical and experimental procedures to determine a wall energy rating (WER) that captures both the thermal and airleakage performance of a wall assembly. The experimental part included two streams of testing: (1) To determine the wall air leakage rate at different conditions and (2) their thermal resistance, R-value, at different temperature differences. An analytical procedure was also developed to calculate WER by combining the heat loss due to thermal transmission and that due to air leakage with the aim of arriving at WER. Six conventional full-scale wood frame wall assemblies were built, two with glass fiber batts and of four with medium density SPF. Some walls were constructed without penetrations and others were built with penetrations. The testing regime included: (i) Initial testing of air leakage and thermal resistance; (ii) conditioning in the dynamic wall test facility according to an established routine; and (iii) retesting for air leakage and thermal resistance. This paper presents the results of six walls included in this project. The focus of this paper will be on presenting a brief summary of the project objective, testing protocol, and the theoretical approach to determine the WER number for the six walls., Peer reviewed article, Published. Received 23 July 2008; accepted 30 June 2009; published online 29 October 2009.
Attic baffle size and vent configuration impacts on attic ventilation
The international residential code (IRC) and most building codes in North America provide attic ventilation codes which allow a certain minimum venting area with an unblocked space by the ceiling insulation. Most of these codes have similar minimum venting ratio, minimum space gap between the roof sheathing and ceiling insulation and vent area location for similar climatic conditions. In this paper, the effects of varying the gap between roof sheathing and ceiling insulation (baffle size) and the locations of vent area under both summer and winter conditions are investigated. Three different baffle sizes and three different locations of the attic vent are used to study their effect on the air distribution and temperature profile inside the attic space. A CFD model is developed and validated using existing experimental measurements. Results show that increasing baffle size hugely affects the air distribution when the air flow is majorly driven by wind. The upper side roof vents have been located at three different locations and our findings show when the upper vent is placed the furthest from the ridge the Air Change per Hour (ACH) value in the attic increases but the air circulation is minimal in the top parts of the attic space and structural elements., Peer-reviewed article, Published. Received 29 November 2014, Revised 26 January 2015, Accepted 28 January 2015, Available online 7 February 2015.
Belief change with uncertain action histories
We consider the iterated belief change that occurs following an alternating sequence of actions and observations. At each instant, an agent has beliefs about the actions that have occurred as well as beliefs about the resulting state of the world. We represent such problems by a sequence of ranking functions, so an agent assigns a quantitative plausibility value to every action and every state at each point in time. The resulting formalism is able to represent fallible belief, erroneous perception, exogenous actions, and failed actions. We illustrate that our framework is a generalization of several existing approaches to belief change, and it appropriately captures the non-elementary interaction between belief update and belief revision., Peer-reviewed article, Published.
Belief manipulation and message meaning for protocol analysis
Agents often try to convince others to hold certain beliefs. In fact, many network security attacks can actually be framed in terms of a dishonest that is trying to get an honest agent to believe some particular, untrue claims. While the study of belief change is an established area of research in Artificial Intelligence, there has been comparatively little exploration of the way one agent can explicitly manipulate the beliefs of another. In this paper, we introduce a precise, formal notion of a belief manipulation problem. We also illustrate that the meaning of a message can be parsed into different communicative acts, as defined in discourse analysis theory. Specifically, we suggest that each message can be understood in terms of what it says about the world, what it says about the message history, and what it says about future actions. We demonstrate that this kind of dissection can actually be used to discover the goals of an intruder in a communication session, which is important when determining how an adversary is trying to manipulate the beliefs of an honest agent. This information will then help prevent future attacks. We frame the discussion of belief manipulation primarily in the context of cryptographic protocol analysis., Peer-reviewed article, Published. Received: 17 January 2014; Accepted: 29 September 2014; Published: 10 October 2014.
Biomechanical characteristics, patient preference and activity level with different prosthetic feet
Providing appropriate prosthetic feet to those with limb loss is a complex and subjective process influenced by professional judgment and payer guidelines. This study used a small load cell (Europa™) at the base of the socket to measure the sagittal moments during walking with three objective categories of prosthetic feet in eleven individuals with transtibial limb loss with MFCL K2, K3 and K4 functional levels. Forefoot stiffness and hysteresis characteristics defined the three foot categories: Stiff, Intermediate, and Compliant. Prosthetic feet were randomly assigned and blinded from participants and investigators. After laboratory testing, participants completed one week community wear tests followed by a modified prosthetics evaluation questionnaire to determine if a specific category of prosthetic feet was preferred. The Compliant category of prosthetic feet was preferred by the participants (P=0.025) over the Stiff and Intermediate prosthetic feet, and the Compliant and Intermediate feet had 15% lower maximum sagittal moments during walking in the laboratory (P=0.0011) compared to the Stiff feet. The activity level of the participants did not change significantly with any of the wear tests in the community, suggesting that each foot was evaluated over a similar number of steps, but did not inherently increase activity. This is the first randomized double blind study in which prosthetic users have expressed a preference for a specific biomechanical characteristic of prosthetic feet: those with lower peak sagittal moments were preferred, and specifically preferred on slopes, stairs, uneven terrain, and during turns and maneuvering during real world use., Peer-reviewed article, Published.

Pages