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Age Determination and Growth of Rainbow Darter (Etheostoma caeruleum) in the Grand River, Ontario
No full textThe accurate determination and validation of age is an important tool in fisheries management. Age profiles allow insight into population dynamics, mortality rates and growth rates, which are important factors in many biomonitoring programs, including the Canadian Environmental Effects Monitoring (EEM) program. Many monitoring studies in the Grand River, Ontario have focused on the impact of municipal wastewater effluent (MWWE) on fish health. Much of the research has been directed at understanding the effects of MWWE on responses across levels of biological organization. The rainbow darter (Etheostoma caeruleum), a small-bodied, benthic fish found throughout the Grand River watershed has been used as a sentinel species in many of these studies. Although changes in somatic indices (e.g. condition, gonad somatic indices) have been included in previous studies, methods to age rainbow darters would provide additional tools to explore impacts at the population level. The objective of the current study was to develop a method to accurately age rainbow darter, validated by use of marginal increment analysis (MIA) and edge analysis (EA) and to characterize growth of male and female rainbow darter at a relatively unimpacted site on the Grand River. Rainbow darter were collected from the Grand River at West Montrose on a monthly basis (May 2014 - June 2015). Size (length, weight) and gonad/liver weight were recorded, and left and right sagittal otoliths were collected. Length-frequency distributions were constructed for the darter population in July and October 2014 to assess population structures.
Darters spawn in the Grand River in late April-early May and young-of-the-year (YOY) darters reached a catchable size, using backpack electro-shockers, by July. A distinct YOY cohort was apparent in the July length-frequency distribution; YOY ranged in length from 1.2–2.5 cm. By October the length-frequency distribution demonstrated that the YOY had started to merge into the other age classes. Direct age determination (using sagittal otoliths) of a subset of the October collections supports that YOY fish are no longer a distinct cohort on the length-frequency distribution, and have assimilated into the rest of the population by this time of year. Direct age determination of fish at this time of the year is therefore necessary to separate age classes.
Examination of rainbow darter otoliths collected monthly was used to validate the use of this structure for accurate age estimation. MIA showed that one annulus was formed per year on sagittal otoliths, and that summer (opaque) growth zone formation began in early summer. EA was able to identify the timing of both summer growth zone and annulus (translucent zone) formation. Summer growth zone formed as early as April, with all fish exhibiting growth by July. Annulus formation was noted in some fish in September, and in all fish by November.
Size-at-age data resulting from the October length-frequency subsampled fish showed differences between male and female rainbow darter. Young fish, both male and female, grow quickly in the first two years (ages 0+ and 1+) and exhibit similar mean length and weight-at-age. Beginning at age 2+ and in each older age group, male rainbow darter become significantly longer and heavier at age compared to females. Additionally, male fish continued to increase significantly in weight each year, with no apparent decrease in weight gain, whereas females did not gain weight significantly after the age of 2+. Estimated von Bertalanffy growth curves for male and female length-at-age relationships further emphasize the difference in male and female growth beginning at age 2+. Furthermore, this model predicted male maximum length to be greater than that of female fish (male: Linf=7.42; female: Linf=6.48). Liver and gonadosomatic indices collected each month indicate increased energy allocation into liver and gonad development in female fish for reproductive purposes, which may account for the difference in male and female size (length/weight) in older age cohorts.
This study has contributed to our understanding of the aging and growth of a small-bodied fish species that is widespread in North America. An accurate and reliable method to age rainbow darter was validated and the knowledge necessary for the addition of growth into biomonitoring studies was established for using rainbow darter as a sentinel species. The ability to accurately estimate age in rainbow darter provides the opportunity to assess growth as an additional population level endpoint in ongoing studies in the Grand River and in other watersheds that are experiencing environmental change
A Use of the Theory of Planned Behaviour to Determine the Social Barriers to the Implementation of Stormwater Green Infrastructure on Private Properties in Dundas, Hamilton, Ontario
Full text linkClimate change has resulted in more extreme rainfall events and most municipalities’ stormwater infrastructure is not prepared to deal with the increased flooding instances that may be associated with the increased rainfall. Updating inferior stormwater infrastructure would put a strain on municipalities’ budgets and require space that is not readily available. A potential option for municipalities is to implement green infrastructure options such as green space, green roofs and bioretention swales. Municipalities may be able to construct some green infrastructure options on publically owned space, however most of the responsibility for implementation will fall on private residents. Previous research has investigated methods of motivating private residents in the implementation of green infrastructure, however very little research has been done on whether residents respond to motivation and what the social barriers to implementation are. This project study focused on three neighbourhoods in the Town of Dundas (Hamilton, ON, Canada) as a case study. Dundas is in a position of pronounced flooding risk because of its location at the valley bottom of a break in the Niagara Escarpment and its past history of flooding. Through a partnership with the Hamilton Conservation Authority, this study used a questionnaire to attempt to elucidate the social barriers to the implementation of green infrastructure on private properties. The questionnaire was theoretically informed using the Theory of Planned Behaviour and analyzed using partial least squares path modelling. The results indicated that behavioural beliefs, attitude, normative beliefs, subjective norm and perceived behavioural control all contributed to the participant’s intention to install green infrastructure and ultimately their final behaviour. The model was able to predict 57% of the variance in intention, based on the associated constructs. Subjective norm contributed the strongest to intention with a path coefficient of 0.542. Attitude had the weakest contribution to intention with a path coefficient of 0.034. Individual question results indicated that time and finances were not statistically significant barriers to the implementation of green infrastructure on private properties. A comparison between the neighbourhoods showed no significant differences in questionnaire answers between any of the three neighbourhoods, however there were differences in income and response rate between the three neighbourhoods. The results from this study can be used to help conservation authorities and municipalities develop engagement and education programs to promote the use of green infrastructure on private properties in order to mitigate the negative effects of climate change
Making the City : A Document on Tactical Urbanism
Full text linkIn the past decade city of Toronto has seen an unprecedented growth in its population. This surge on growth of the city poses questions about the quality of its future public and private spaces and its patterns of growth.
In the face of these questions the thesis briefly navigates the political and economic landscape of Toronto and its most common practices of city making in search for alternatives. It proposes a new type of urbanism that is driven by ordinary people. This urbanism allows for building a city that is more reflective of the multitude and complex sum of the urban population of Toronto and is more compatible with the rapid cycles of economy, new paradigms in culture and the unforeseen conditions of growth. Tactical Urbanism, as a response to aforementioned conditions, uses tactics to influence the long term planning, rearrange power in the field of action and make use of limited resources. According to Michel De Certeau, tactic is the ruse of players in a field that is dominated by others. In this case the field is the city, the objective is building public and shared spaces and the City and developers are the dominant players.
In this thesis four separate projects, that were developed and undertaken between June 2012 and October 2013 in Toronto by the author and in collaboration, are presented as experiments for examining the effectiveness, techniques and possibilities within Tactical Urbanism. Developed mostly based on the concept of détournement (diversion), borrowed from the Situationist International, two streams of experiment are developed: one that is defined by temporary appropriation of space and the other by narrating the city through dynamic and ludic space of walking. Both of these streams of action are concerned with the personal relationship of people and places and focus on fostering a sense of belonging and ownership over the urban built environment
Unsupervised Aspect Discovery from Online Consumer Reviews
No full textThe success of on-line review websites has led to an overwhelming number of on-line consumer reviews. These reviews have become an important tool for consumers when making a decision to purchase a product. This growth has led to the need for applications that enable this information to be presented in a way that is meaningful. These applications often rely on domain specific semantic lexicons which are both expensive and time consuming to make.
The following thesis proposes an unsupervised approach for product aspect discovery in on-line consumer reviews. We apply a two step hierarchical clustering process in which we first cluster based on the semantic similarity of the contexts of terms and then on the similarity of the hypernyms of the cluster members. The method also includes a process for assigning class labels to each of the clusters. Finally an experiment showing how the proposed methods can be used to measure aspect based sentiment is performed.
The methods proposed in this thesis are evaluated on a set of 157,865 reviews from a major commercial website and found that the two-step clustering process increases cluster F-scores over a single round of clustering. Finally, the proposed methods are compared to a state of the art topic modelling approach by Titov and McDonald (2008)
The Role of Food in Tourists' Experiences
No full textThe preparation, marketing and consumption of food are complex social-economic processes that still require an extensive amount of original research, and this is perhaps especially true in cross-cultural contexts. To gain a clearer understanding of the role of food and cuisine in trans-cultural touristic experience, it is necessary to acknowledge multidimensional criteria rather than concentrating solely on one aspect such as food preferences or motivation. Given the scarcity of relevant research, the main purpose of the present study is to analyze food and dining vis-a-vis the phases of the cross-cultural tourist experience, the influences upon it, and its outcomes, through which a deeper insight into the roles of food in the tourist experience can be obtained. The research takes the form of a case study exploring the experiences of both Western and non-Taiwanese Asian tourists in Taiwan.
An on-site survey was conducted at Taiwan Taoyuan International Airport throughout the month of May 2012. A total of 633 respondents comprising 425 Asian tourists from seven countries and 208 Western tourists from ten countries completed the questionnaire. Results of this study have identified key attributes of how Asian and Western tourists perceived food while travelling in Taiwan, and challenge conventional conceptual approaches to understanding the roles of food in tourism experience, by taking into account the phased nature of touristic experience. Among other findings, Asian tourists in the sample were more likely to view food as a major motivation, and to engage more actively in food experience, than their Western counterparts. The study also upholds the hypothesis that touristic experience is multi-dimensional, insofar as it confirmed the theoretical validity of the phases of the tourist experience (pre-experience, during-experience, and post-experience) for quantitative evaluation of the roles of food and cuisine
Iterative Coupled Shell/Tube Simulation of Waste Heat Boilers using Computational Multiphysics
Full text linkRemoval of sulphur from fossil fuels is important in order to avoid the emission of
sulphur oxides into the atmosphere, exposure to which has negative health and environ-
mental effects. Sulphur is removed from refinery petrochemical products via the Claus
process which contains a waste heat boiler (WHB). These WHBs are exposed to extreme
temperatures and corrosive conditions, yet they are expected to operate continuously for
years at a time.
Typically WHBs have been designed using empirical correlations and heuristics, but
more recently using process and multiphysics simulation. In this work a proof of concept
for the numerical simulation of a WHB and its protective insulation is demonstrated.
Continuum multiphysics models for both shell and tube side of a WHB are developed. An
iterative coupling method for the determination of steady-state numerical solution of these
models is then used to simulate a sub-region of a typical WHB.
Simulation results for the tube-side of the WHB predict both the temperature profile
and nature of the turbulent energy transport in the inlet region, highlighting complex flow
profiles. Simulations of the shell-side of the WHB predict the multiphase convective boiling
behaviour in the bulk (far from wall effects). Finally, preliminary results of the coupled
shell/tube configurations are presented and compared to previous results
Biofiltration in Drinking Water Treatment: Reduction of Membrane Fouling and Biodegradation of Organic Trace Contaminants
Full text linkThe goal of drinking water treatment is to produce and deliver safe water to the consumers. To achieve these objectives water treatment plants are designed based on the concept of the multibarrier approach which combines several drinking water treatment processes in order to increase the reliability of the system. The presence of pharmaceutically active compounds (PhACs), personal care products (PCPs) and endocrine disrupting compounds (EDCs) in drinking water sources is becoming a concern, because of chronic and indirect human exposure to contaminant mixtures at sub-therapeutic levels via drinking water consumption.
Membrane filtration can be an efficient treatment process to remove microorganisms and/or trace organic contaminants from drinking water sources. However, membranes are confronted by a major limitation: membrane fouling. Fouled membranes suffer from a loss in performance either leading to a reduction in flux or a higher pressure requirement. Generally, membrane fouling increases the need for membrane maintenance measures such as backwashing and chemical cleaning which has a negative impact on the operating costs and membrane life time. Severe membrane fouling may even impact permeate quality and/or compromise membrane integrity.
The aim of this study was to establish if biofiltration pretreatment without prior coagulation would be able to control membrane fouling in natural waters. The second objective investigated the removal of trace organic contaminants by individual treatment processes (i.e. biofiltration and membrane filtration). Parallel to this work, the presence and concentration of selected trace organic contaminants in Grand River (Ontario, Canada) were determined. The trace organic contaminants investigated included atrazine, carbamazepine, DEET, ibuprofen, naproxen, and nonylphenol.
Direct biofiltration pretreatment (no coagulation) significantly reduced both reversible and irreversible fouling of ultrafiltration membranes. Results showed that the different degree of reduction of hydraulically reversible fouling was primarily attributed to the absolute concentration of a specific fraction of the dissolved organic matter (i.e. biopolymers) in the biofilter effluent (i.e. membrane feed). The study also suggests that the composition of biopolymers rather than their absolute concentration is important for the control of irreversible fouling.
High pressure membranes such as nanofiltration membranes are also subjected to fouling. Results showed that biofiltration pretreatment was able to achieve fouling control but membrane characteristics (i.e. molecular weight cut off) influence the efficiency of the pretreatment. This study also showed that not only biopolymers but also humic substances and low molecular weight acids are being rejected by nanofiltration membranes.
Selected trace organic contaminants were detected in Grand River water in the low ng/L range with detection frequencies between 48 to 100%. Seasonal occurrence patterns could be explained by compound use and possible degradation mechanisms. These results confirm the impact of human activities on the Grand River.
This study showed that under the right conditions rapid biofiltration is capable of completely removing biodegradable emerging contaminants at ng/L concentrations. DEET, ibuprofen, and naproxen were biodegradable and therefore amenable to removal while carbamazepine and atrazine were recalcitrant. Factors such as empty bed contact time, influent concentration, and temperature influenced the biodegradation kinetics.
Finally, both membrane and contaminant properties influenced the degree of rejection achieved by nanofiltration membranes. Results showed that steric hindrance and electrostatic repulsion were the major rejection mechanisms.
Several benefits are associated with the use of direct biofiltration for drinking water treatment. These benefits include: the removal of easily biodegradable organic matter leading to biologically stable effluents; the removal of biodegradable trace organic contaminants contributing to the multibarrier approach; the absence of chemicals coagulation which is of advantage for operations in isolated areas; the simple operation and maintenance which is an advantage for locations with limited trained operators; and finally if used prior to membrane filtration biofiltration pretreatment can control membrane fouling
Understanding food consumption behaviors; Prospects for shifting towards sustainable diets
Full text linkEvery day, every one of the 8 billion people on the earth must decide about what to eat. By 2050, the world's population will have grown by at least 2 billion people, raising the question of whether we will be able to continue eating the same way. Moreover, Energy and resource use, meat consumption, and food transport have greatly threatened the existing food system. To preserve a healthy and sustainable diet for everybody, a potential solution for this challenge can be shifting dietary choices to mitigate the general need for food supply and related resources. However, it is a challenge to achieve realistic dietary adjustments because of the complicated nature of the variables that influence food choices. While making purchasing and eating decisions, people might be influenced by personal factors such as health, price and, sensory appeal or by environmental factors such as food choice influencers, food culture and, sociability. Demographic status and previous diet changes also play important roles in shaping one’s food behaviors. This thesis creates a model based on the Social Cognitive Theory to categorize these variables, and then conducts an exploratory analysis of the model using an online survey. The goal of this study is to understand the primary variables that influence Canadians' food choices, as well as how these factors differ depending on socio-demographic characteristics including gender, age, and education levels as well as how previous diet changes can affect the significance of factors.
The preliminary model identifies eight major personal determinants and three major environmental determinants that influence Canadians' food choices. Having these factors identified helps break down the decision-making process one goes through when making food choices. To conduct an exploratory analysis of this model, a quantitative approach was used, and an online survey was sent to 3623 Canadians across the country. The result of this study revealed that Price and Sociability are the dominant constructs for Canadians in their food choices. These two constructs remain almost consistently important over the three socio-demographic characteristics examined as well. Socio-demographics reported significantly different attitudes on five out of eleven constructs.
Understanding consumer attitudes and behaviors around dietary patterns are critical in identifying significant leverage points for positively affecting future food requirements and targeting different segments of consumers for diet shifts that are achievable. The results of this study highlight the key connections between each factor and consumer groups for policymakers and marketers to act accordingly. Taking a step further, we can apply the results of this study to other locations around the world and guide public food purchasing decisions to be more sustainable
Generalized GCDs as Applications of Vojta’s Conjecture
Full text linkStarting with an analysis of the result that for any coprime integers a and b, and some ϵ > 0, we have eventually that gcd(a^n − 1,b^n − 1) < a^ϵn holds for all n, we are motivated to look for geometric reasons why this should hold. After some discussion on the general geometry and arithmetic needed to examine these questions, we take a quick look into how Vojta’s conjectures provide a generalization of our first result. In particular, we also note a case where this implies a similar equality on particular elliptic curves
Studying Transformer Behavior Under Markovian Input
No full textTransformers have achieved remarkable success in modeling sequential data, yet a principled theoretical understanding of their behavior remains limited. A recent framework has analyzed transformers through the lens of first-order Markov chains, providing four theorems that characterize the loss landscape and the conditions under which global minima and bad local minima arise. However, the theoretical analysis in that work was restricted to first-order processes, leaving open questions about the behavior of transformers on higher-order Markovian data.
This thesis extends the theoretical framework to the case of second-order Markov chains. Specifically, all four theorems originally established for first-order chains are formally proven for second-order chains, thereby broadening the mathematical foundation for analyzing transformers on sequential data. Also, we show that these theorems are also true on another type of transformer architecture (attention-only transformers), given first- and second-order Markovian input data. Furthermore, experimental evaluations demonstrate that the empirical learning dynamics for second-order chains align closely with the simplified second-order model proposed in prior work, confirming that the theoretical predictions hold in practice.
By closing the gap between first-order theory and second-order behavior, this study contributes to a deeper understanding of transformers’ sequential modeling capabilities. The findings highlight the conditions under which transformers correctly capture second-order dependencies and provide new insights into their limitations and potential extensions for higher-order processes