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Title: SOCIAL MECHANISM OF SOCIAL SUPPORT PROVISION : A BEHAVIORAL STUDY OF ONLINE SUPPORT GROUPS
Creator: Lee, Sanguk
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The popularity of Online Support Groups (OSGs) is ever increasing as OSGs enable people with (dis)similar health conditions to exchange social supports easily. Social support provision is a critical activity for individual well-being and community sustainability, yet the underlying social mechanism that promotes social support provision is underexplored. Employing social capital theory, the current study examines how brokerage and closure structures yield different forms of social capital...
Show moreThe popularity of Online Support Groups (OSGs) is ever increasing as OSGs enable people with (dis)similar health conditions to exchange social supports easily. Social support provision is a critical activity for individual well-being and community sustainability, yet the underlying social mechanism that promotes social support provision is underexplored. Employing social capital theory, the current study examines how brokerage and closure structures yield different forms of social capital such as non-redundant information and trust, which subsequently facilitate the diverse dimensions of informational and emotional support provisions, including quantity, quality, and timing. Methodologically, the study utilizes computational methods to collect online behavioral data from an online cancer community, measure network metrics and support provision behaviors, and capture the dynamic relationships between the network structure, social capital, and support provision behaviors. Results indicate that the brokerage structure and non-redundant information enhance the volume, uniqueness, and speed of information support provision. Although the closure structure and trust have a positive influence on the quality of emotional support, their overall impacts are limited in promoting information and emotional supports in the context of OSGs. The findings also indicate the importance of considering the dynamic development stage of OSGs in understanding the social mechanism of support provisions.
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Title: IS AFRICAN AGRICULTURE EXHIBITING BOSERUPIAN INTENSIFICATION? EVIDENCE FROM RURAL GHANA AND NIGERIA
Creator: Nutsugah, Godwin Kwesi
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The recent increase in the use of capital-using and labor-saving inputs in various parts of Africa has prompted researchers to investigate whether farming systems are innovating consistently with the Boserupian theory of intensification. According to the Boserupian theory, trends in factor price ratios will encourage farmers to substitute more expensive factors with less expensive factors. However, farmer responses to changing factor price trends may be blunted for many reasons, some of which...
Show moreThe recent increase in the use of capital-using and labor-saving inputs in various parts of Africa has prompted researchers to investigate whether farming systems are innovating consistently with the Boserupian theory of intensification. According to the Boserupian theory, trends in factor price ratios will encourage farmers to substitute more expensive factors with less expensive factors. However, farmer responses to changing factor price trends may be blunted for many reasons, some of which could be addressed through public sector action. Using multi-year nationally representative surveys from Ghana and Nigeria, this study therefore broadly investigates the Boserupian hypothesis by analyzing how agricultural households in rural Ghana and Nigeria intensify input use in response to variations in relative input prices. Furthermore, this paper examines whether effects differ by geographic location within a particular nation. The findings from rural Ghana and Nigeria suggest that farmers intensify inputs partly but not entirely consistent with the Boserupian theory. These results indicate that household input use constraints may be systematically different, highlighting the need for regionally appropriate policies or programs that enable households to react more rapidly and entirely to changes in factor price ratios. This study could also provide policymakers, crop scientists, and engineers with insights into the expected trajectory of technical change in the farming systems and guide them in developing appropriate farm technologies and policies.
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Title: LIFE IS NOT JUST BLACK AND WHITE : THE INFLUENCE OF SOCIAL CLASS CUES ON RACE IN AN AFFECT MISATTRIBUTION PROCEDURE
Creator: Carrillo, Alejandro
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Indirect measures of racial bias, such as the Affect Misattribution Procedure, Evaluative Priming Task, and the Implicit Association Task, have been used to provide evidence of stereotypical associations and valenced evaluations towards different racial categories. However, a common limitation shared across these tasks is the tendency to use simplistic racial stimuli that do not capture or account for the multiple categories people may belong to. That is, it is unlikely that people are...
Show moreIndirect measures of racial bias, such as the Affect Misattribution Procedure, Evaluative Priming Task, and the Implicit Association Task, have been used to provide evidence of stereotypical associations and valenced evaluations towards different racial categories. However, a common limitation shared across these tasks is the tendency to use simplistic racial stimuli that do not capture or account for the multiple categories people may belong to. That is, it is unlikely that people are perceived and evaluated along a single feature (i.e., race) but rather at the intersections of multiple categories (i.e., race, age, attractiveness, social class, etc.). Social class, in particular, is a strongly evaluated category and has been shown to share stereotypic associations with race (Moore-Berg & Karpinski, 2019). Thus, this thesis investigated the effects of social class on racial evaluations in an AMP task. Social class was manipulated using occupational clothing in Study 1 and residential areas in Study 2, while race was limited to Black and White men. Across two studies, participants demonstrated a consistent, unexpected pro-Black bias. In addition, an effect of social class was only found in Study 2 such that high-class primes were associated with positive responses. Regarding social class, the results suggest that the manipulations chosen may play an important role in categorization; however, future research is needed to examine just how different class representations impact evaluation.
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Title: AGENTS OF SEE CHANGE : CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968
Creator: Brothers, Heather
Date: 2022
Collection: Electronic Theses & Dissertations
Description: ABSTRACTAGENTS OF SEE CHANGE: CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968ByHeather Brothers This dissertation examines Catholic women's organizations in West Germany from 1945 to 1968. Women in organizations like the Central Association of Catholic Women and Mothers’ Organizations (ZKFM) were important agents of change within both West German society and the Catholic Church. Despite being largely left out of scholarly discussions about the postwar period, West German Catholic...
Show moreABSTRACTAGENTS OF SEE CHANGE: CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968ByHeather Brothers This dissertation examines Catholic women's organizations in West Germany from 1945 to 1968. Women in organizations like the Central Association of Catholic Women and Mothers’ Organizations (ZKFM) were important agents of change within both West German society and the Catholic Church. Despite being largely left out of scholarly discussions about the postwar period, West German Catholic women and the knowledge they created fundamentally shaped the intellectual culture of the Catholic milieu during this era. The ZKFM, and other organizations like it, gave Catholic women a platform within the Church that both limited the scope of their ideas and actions, but also provided these women with networks and connections that empowered them to effectively challenge Catholic dogma and tradition and to intervene in West German debates about women’s role in family, society, and state. By studying the intellectual work of Catholic women and their organizational labor, I argue that we can better understand the relationship between women, the Church, and West German society. This dissertation explores how interactions between conceptions of gender and Catholic faith are integral to understanding both women’s place within the structures of Church and state and also how women worked to shape these structures to their own ends. Women in the ZKFM expressed a wide diversity of opinions, and the organization allowed and encouraged new interpretations on both faith and gender that helped to set the association’s agenda moving forward. While influenced by conservative Catholic tradition and a conservative West German state, the diversity within the ZKFM also emboldened members to explore feminist ideas and other progressive pursuits. When we look closely at ZKFM conferences, publications, benevolent activities, and public interventions, we can see that these women and their intellectual work played a significant role in shaping the landscape of postwar West Germany.
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Title: Computational methods to investigate connectivity in evolvable systems
Creator: Ackles, Acacia Lee
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Evolution sheds light on all of biology, and evolutionary dynamics underlie some of the most pressing issues we face today. If we can deepen our understanding of evolution, we can better respond to these various challenges. However, studying such processes directly can be difficult; biological data is naturally messy, easily confounded, and often limited. Fortunately, we can use computational modeling to help simplify and systematically untangle complex evolutionary processes. The aim of this...
Show moreEvolution sheds light on all of biology, and evolutionary dynamics underlie some of the most pressing issues we face today. If we can deepen our understanding of evolution, we can better respond to these various challenges. However, studying such processes directly can be difficult; biological data is naturally messy, easily confounded, and often limited. Fortunately, we can use computational modeling to help simplify and systematically untangle complex evolutionary processes. The aim of this dissertation is therefore to develop innovative computational frameworks to describe, quantify, and build intuition about evolutionary phenomena, with a focus on connectivity within evolvable systems. Here I introduce three such computational frameworks which address the importance of connectivity in systems across scales.First, I introduce rank epistasis, a model of epistasis that does not rely on baseline assumptions of genetic interactions. Rank epistasis borrows rank-based comparison testing from parametric statistics to quantify mutational landscapes around a target locus and identify how much that landscape is perturbed by mutation at that locus. This model is able to correctly identify lack of epistasis where existing models fail, thereby providing better insight into connectivity at the genome level.Next, I describe the comparative hybrid method, an approach to piecewise study of complex phenotypes. This model creates hybridized structures of well-known cognitive substrates in order to address what facilitates the evolution of learning. The comparative hybrid model allowed us to identify both connectivity and discretization as important components to the evolution of cognition, as well as demonstrate how both these components interact in different cognitive structures. This approach highlights the importance of recognizing connected components at the level of the phenotype.Finally, I provide an engineering point of view for Tessevolve, a virtual reality enabled system for viewing fitness landscapes in multiple dimensions. While traditional methods have only allowed for 2D visualization, Tessevolve allows the user to view fitness landscapes scaled across 2D, 3D, and 4D. Visualizing these landscapes in multiple dimensions in an intuitive VR-based system allowed us to identify how landscape traversal changes as dimensions increase, demonstrating the way that connections between points across fitness landscapes are affected by dimensionality. As a whole, this dissertation looks at connectivity in computational structures across a broad range of biological scales. These methods and metrics therefore expand our computational toolkit for studying evolution in multiple systems of interest: genotypic, phenotypic, and at the whole landscape level.
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Title: A STUDY OF MARGINALIZED NEWS PUBLICATION COMMENTERS AND THEIR MOTIVATIONS AND PERCEPTIONS OF LGBTQIA+ NEWS FORUMS
Creator: Kim, Soojeong
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The majority of news comment studies focus on elite news publications such as The New York Times. These studies typically arrive at one of two conclusions: (a) news comment forums are uncivil spaces and (b) White men dominate the conversation spaces on news websites. Yet we know little about how marginalized news commenters on alternative news publications’ online comment forums perceive news spaces and participate in them. Therefore, 22 commenters active in commenting on marginalized (i.e.,...
Show moreThe majority of news comment studies focus on elite news publications such as The New York Times. These studies typically arrive at one of two conclusions: (a) news comment forums are uncivil spaces and (b) White men dominate the conversation spaces on news websites. Yet we know little about how marginalized news commenters on alternative news publications’ online comment forums perceive news spaces and participate in them. Therefore, 22 commenters active in commenting on marginalized (i.e., LGBTQIA+) publications were interviewed to investigate news commenters’ perceptions and motivations. The Social Identity and Bounded Generalized Reciprocity theoretical frameworks suggest these news comment forums should be perceived as safer and more civil spaces due to their homogenous nature. Social Identity Theory suggests that commenters should behave in a more community-oriented way because of in-group favoritism, while Bounded Generalized suggests individuals’ commenting motivations might be driven by the reciprocal expectation that in-group members will positively reciprocate their comments and support their reputational standing. The interview results rooted in the SIT and BGR theoretical lenses provided support for those commenting motivations: (1) perceived similarity, (2) reciprocity, and (3) reputation acknowledgment, which led them to perceive that interactions are civil and safe on LGBTQIA+ news forums.
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Title: Plasma Based Methods for the Synthesis and Deposition of Nanoparticles
Creator: Ho, Alexander
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Nanoparticles exhibit tunable properties that offer the opportunity to improve existing technologies. Nanoparticles also possess emergent properties that are not shared by their bulk scale counterparts; this difference in properties allows for application of materials in devices and processes that were traditionally unsuitable. For semiconducting nanoparticles, the emergent and tunable properties hold promise for applications in solar cells, light emitting devices, sensors, catalysis, and a...
Show moreNanoparticles exhibit tunable properties that offer the opportunity to improve existing technologies. Nanoparticles also possess emergent properties that are not shared by their bulk scale counterparts; this difference in properties allows for application of materials in devices and processes that were traditionally unsuitable. For semiconducting nanoparticles, the emergent and tunable properties hold promise for applications in solar cells, light emitting devices, sensors, catalysis, and a variety of other spaces.Explored first was the syntheis of InN, GaN, and InGaN at low pressure. These materials possess properties suitable for high-power and high-frequency electronics applications. The materials also possess bandgaps that span from the IR to the UV allowing for the use in a host of optoelectronic applications. A low-pressure RF plasma reactor was used to dissociate precursor gases whose subsequent reactions formed the nanoparticles. Nanoparticles were then collected and characterized with a host of techniques. Experiments were conducted that demonstrated the synthesis of crystalline nanoparticles with narrow size distributions. It was shown that particle size and crystallinity could be controlled through modulation of residence time and RF power respectively. This method demonstrated the synthesis of luminescent InGaN nanoparticles without any subsequent surface modification or post-synthesis treatment. To eliminate the time and capital costs of vacuum equipment and processes an atmospheric pressure microplasma operated with ambient surroundings was investigated. With this method crystalline silicon nanoparticles were synthesized. OES and FTIR were used in conjunction to ascertain if particles were synthesized in an oxygen contaminated environment. Results of the experiments indicatethat particles were not exposed to oxygen in the reaction volume. Lastly an integrated atmospheric pressure synthesis reactor and aerosol jet printing process are described. Such a process would be useful for fabrication or prototyping of devices that require nanoaprticles. Combination of the reactor with a motorized stage and gantry allowed for deposition of nanoparticles with linewidths down to 100 microns. Methods to improve impaction efficiency were implemented and allowed for capture of sub-5 nm particles that exhibited luminescence at 680 nm. Also demonstrated was the control of synthesis parameters at the time of deposition to deposit particles with spatially varied properties.
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Title: EVALUATION OF DYNAMIC SPEED FEEDBACK SIGNS ON FREEWAY INTERCHANGE RAMPS
Creator: Mahmud, Md Shakir
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Dynamic speed feedback signs (DSFS) are promising countermeasure to reduce curve speeds and subsequent lane departures at freeway interchange ramps, although their use in such contexts has been limited. Consequently, the impact of DSFS on driver performance at interchange ramps has remained unproven. To that end, research was performed to determine the effect of DSFS installed at freeway interchange ramps on measures of driver behavior, particularly vehicular speeds approaching and entering...
Show moreDynamic speed feedback signs (DSFS) are promising countermeasure to reduce curve speeds and subsequent lane departures at freeway interchange ramps, although their use in such contexts has been limited. Consequently, the impact of DSFS on driver performance at interchange ramps has remained unproven. To that end, research was performed to determine the effect of DSFS installed at freeway interchange ramps on measures of driver behavior, particularly vehicular speeds approaching and entering the ramp curve. To accomplish this objective, a series of field evaluations were conducted at six freeway interchange ramps possessing significant horizontal curvature. Several factors were tested during these evaluations, including: DSFS messaging strategy, positioning of the DSFS with respect to the start of the curve and side of the ramp, physical characteristics of the DSFS, radar detection range, interchange type, and temporal effects. Speed data were collected using one of these three techniques selected based on the site characteristics and types of data desired: 1) a series of high-definition video cameras, 2) handheld LIDAR, and 3) a speed-trailer. Several measures of effectiveness including speed at different locations, speed of drivers at different speed percentiles, and initial braking location were analyzed using appropriate regression techniques. Considering all phases of the field evaluation, it was concluded that DSFS are an effective countermeasure for reducing the speeds of vehicles approaching and entering horizontal curves on freeway exit ramps. The most critical aspect influencing the effectiveness of the DSFS as a speed reduction countermeasure was the longitudinal positioning of the sign relative to the ramp curve. Overall, the presence of a DSFS positioned near the start of the curve resulted in curve entry speeds that were, on average, 1.5 mph to 5.3 mph lower than without a DSFS present at the site. When the DSFS was present near the start of the curve, the lowest curve entry speeds were observed for cases where the feedback message activated when vehicles were within 250 to 400 ft of the start of the curve. Regarding DSFS lateral position, both the right-side-mounted and forward-mounted (i.e., ramp gore area) installations resulted in similar curve entry speeds. Furthermore, there were no discernable differences in curve entry speeds between 15-inch and 18-inch display panels, nor were speeds impacted by the inclusion of an advisory speed panel. In terms of feedback message, the most effective strategy was to display the measured speed alternating with a SLOW DOWN message. The effects on driver behavior associated with the DSFS were consistent between system interchanges and service interchanges, and across all vehicle types. The DSFS was equally effective irrespective of the mainline speed limit or ramp advisory speed. However, more pronounced speed reduction effects were observed for faster drivers (i.e., those within the highest quantiles) compared to the slower or average drivers. Furthermore, there was no evidence of temporal changes in driver behavior during the initial 14 months of operation of the permanent DSFS installation evaluated here. Finally, message activation did not show any significant effect on the speeds of mainline (i.e., non-exiting) vehicles. These findings were subsequently utilized towards the development of guidelines and recommendations for future use of DSFS at freeway interchange ramps.
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Title: Network Embeddings for Data Clustering, Transition State Identification, and Energy Landscape Analysis
Creator: Mercurio, Paula
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Many chemical and biochemical systems can be intuitively modeled using networks. Dueto the size and complexity of many biochemical networks, we require tools for efficient network analysis. Of particular interest are techniques that embed network vertices into vector spaces while preserving important properties of the original graph. In this article, we investigate several aspects of node embedding, propose a novel method of generating node embeddings, and explore applications to biochemical...
Show moreMany chemical and biochemical systems can be intuitively modeled using networks. Dueto the size and complexity of many biochemical networks, we require tools for efficient network analysis. Of particular interest are techniques that embed network vertices into vector spaces while preserving important properties of the original graph. In this article, we investigate several aspects of node embedding, propose a novel method of generating node embeddings, and explore applications to biochemical systems. We introduce a new method for generating low-dimensional node embeddings for directed graphs using random walk sampling and demonstrate the usefulness of this method for identifying transition states of stochastic chemical reaction systems, detecting relationships between nodes, and studying the structure of the original network. In addition, we propose an efficient scheme for numerical implementation of network embedding based on deterministic computations of commute times rather than random walk trials. We develop a novel implementation of stochastic gradient descent (SGD) based on a low-dimensional sparse approximation of the original random walk on the graph, and show that this approach can improve the performance of node embeddings. This method can be further extended for entropy-sensitive adaptive network embedding by incorporating principles from metadynamics and hierarchical network embedding, allowing for applications to the analysis of molecular structures. By adjusting the edge weights of the network by a Gaussian term, similarly to the metadynamics approach, we ensure that areas that have already been explored extensively by the random walk (i.e., the edges with the largest weights) will be de-emphasized over time, allowing additional iterations of the embedding process to reveal details about other areas of the graph. We show that this approach lends itself well to systems that are influenced by entropy or temperature effects and biochemical systems where the potential energy landscape depends on the system’s configuration at a given time, either by itself or in conjunction with transition path theory. We demonstrate the effectiveness and performance of each of our methods on several datasets and biochemical examples.
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Title: INVESTIGATING TEST DELIVERY MODES WITHIN VIDEO-CONFERENCED ENGLISH SPEAKING PROFICIENCY ASSESSMENT
Creator: Choi, Jin Soo
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Nonverbal behavior is essential in human interaction (Gullberg, de Bot, & Volterra, 2008; McNeill, 1992, 2005). For second language speakers, nonverbal features can be helpful for successful and efficient communication (e.g., Dahl & Ludvigsen, 2014). However, due to the complexity of nonverbal features, language testing institutions have conventionally employed an asynchronous format (e.g., audio-only mode), focusing on the test-taker’s verbal features. Recently, the advance in technology,...
Show moreNonverbal behavior is essential in human interaction (Gullberg, de Bot, & Volterra, 2008; McNeill, 1992, 2005). For second language speakers, nonverbal features can be helpful for successful and efficient communication (e.g., Dahl & Ludvigsen, 2014). However, due to the complexity of nonverbal features, language testing institutions have conventionally employed an asynchronous format (e.g., audio-only mode), focusing on the test-taker’s verbal features. Recently, the advance in technology, and most importantly, the coronavirus pandemic (COVID-19) outbreak in late 2019 and early 2020, have accelerated the use of video-conferencing applications in educational contexts, including speaking tests (Nakatsuhara, Inoue, Berry, & Galaczi, 2021). Accordingly, the synchronous test delivery mode (video-conferencing), which presents test-takers’ visual information, is a timely and necessary approach to addressing the impact of nonverbal features on L2 oral communication. In response to these issues, I investigated the comparability of different delivery modes of speaking proficiency assessment. This study aimed to understand the dimensionality of the measured speaking construct and the impact of test-takers’ visual information on rater behavior. Two datasets were used to address the research goals: first dataset (i.e., dataset 1) included scores of 110 test-takers, assessed by eight trained raters; second dataset (i.e., dataset 2) included scores of 284 prospective international teaching assistants (ITAs), assessed by 12 professional and certified raters. I collected dataset 1, and English language learning and testing program at a Midwest University provided dataset 2. I used two quantitative techniques to analyze both datasets: confirmatory factor analysis (CFA) and Multifaceted Rasch model (MFRM) analysis. For dataset 1, I qualitatively analyzed the raters’ verbal reports. Dataset 1 had an asynchronous format; all test-takers’ performances were recorded for rating. Eight trained raters gave scores to the audio-recorded and video 1 mode (test-taker and test giver were displayed). Three weeks later, the raters assessed video 2 mode (only test-taker’s visual information was displayed). Within one month, raters participated in a one-on-one semi-structured interview. Dataset 2 stems from an operational testing context. This dataset has only scores, as I borrowed the data from the operational English testing program at the university. The scores were first given by examiners in a synchronous format (Live mode) and later by raters in an asynchronous format (Recorded mode). CFA findings indicated the multi-dimensional aspect of the underlying construct of speaking for both datasets, but the high inter-correlations showed that these are associated. Findings of MFRM revealed that raters showed leniency when rating (a) video mode over audio-only mode (dataset 1) and (b) synchronous mode over asynchronous mode (dataset 2). Findings suggest that using the video-conferenced delivery mode may be beneficial. However, the degree of usefulness across video modes differed, and how the raters utilized test-takers’ nonverbal behaviors (e.g., gaze) varied. Thus, I decided that further investigation is needed to sufficiently support the use of video-conferencing applications to complement the physical face-to-face delivery mode. Overall, future research is highly recommended regarding the standardization of scoring of nonverbal features about the types of video mode, which would assist with the practical and valid application of virtual speaking tests.
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Title: EXPLORING THE TRANSITION FROM INITIATION TO DEPENDENCE ON ALCOHOL
Creator: Walsh, Madison
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Objective:This study aims to expand on published literature regarding the transition from alcohol initiation to alcohol dependence among newly initiated alcohol users. The main aim is to broaden the estimates to include a larger age group, comparing male and female differences, and exploring potential associations that link days of drinking with the occurrence of alcohol dependence among newly initiated drinkers (NID) and individuals who are alcohol dependent. An additional goal is to assess...
Show moreObjective:This study aims to expand on published literature regarding the transition from alcohol initiation to alcohol dependence among newly initiated alcohol users. The main aim is to broaden the estimates to include a larger age group, comparing male and female differences, and exploring potential associations that link days of drinking with the occurrence of alcohol dependence among newly initiated drinkers (NID) and individuals who are alcohol dependent. An additional goal is to assess the criteria in DSM-IV and DSM-5 regarding alcohol use disorders (AUD), thus exploring the change in the questions that the United States National Surveys on Drug Use and Health has been using to measure AUD for the survey each year. In conclusion, I propose a protocol for clinicians to use to gauge their disagreement with the DSM-5 unit-weighting of individual diagnostic criteria versus alternatives that allow clinicians to weight some criteria more heavily than others. I have included this proposed protocol in my thesis as a direction for future research. Due to the SARS-COV-2 pandemic and other circumstances, I offer the protocol, but I do not provide empirical estimates. The empirical estimates remain on the agenda for future research.Study Design: The United States National Surveys on Drug Use and Health (US, NSDUH, 2002-2019) draw samples of the nation’s population, take standardized measurements, and provide the primary data for this research. The sample population included non-institutionalized U.S. civilian residents aged 12 years and older, and NSDUH seeks to produce a nationally representative sample of this segment of the U.S. population. For my thesis research project, I tapped the ‘Restricted-use Data Analysis System (RDAS) online analysis tool, which organizes the datasets in year-pairs, from which analysis-weighted study estimates and variances can be derived. After deriving these estimates, I produced meta-analytic summaries with 95% confidence intervals (CI). Frequency distributions are used for the analysis-weighted estimates of the association involving days of drinking.Results:Looking across 2002-2019, the meta-analytic summary for newly initiated alcohol users who became alcohol-dependent within the first year of use is 1.67% [95% CI: (1.46, 1.95)]. For every 100 NIDU, roughly 1.5-2.0 had become dependent when assessed within the first year after the first full drink. Focusing on male and female differences, females had a modestly different meta-analytic estimate for the transition from initiation to the dependence on alcohol (1.86% [95% CI: (1.6, 2.2)] versus the corresponding male estimate of 1.47% [95% CI: (1.2, 1.8], but this female-male variation is unremarkable when the overlap of 95% CI is taken into account. The most common drinking days for all newly initiated alcohol users irrespective of alcohol dependence from 2002 to 2019 were 1-11 days (78.1%), compared to 100-299 days for all alcohol-dependent users from 2002 to 2019 (53.9%). Looking at the 2002-2020 data for the same estimates, there was not an appreciable difference in the meta-analytic summary for newly initiate alcohol users who became alcohol-dependent within the first year of use [1.69% (95% CI: (1.45, 1.91]). Adding the 2020 data to the male estimate decreased the overall meta-analytic summary to 1.34% [95% CI (1.1, 1.7). The female estimate did not change appreciably, increasing to 1.90 from 1.86% [95% CI (1.63, 2.21)]. Finally, the number of individuals with alcohol disorders increased greatly in 2020 when using DSM-5 criteria (9.9%, 95% CI (9.4, 10.6)) versus DSM-IV criteria (3.2, 95% CI (2.9, 3.5). Conclusion: The estimate of newly incident alcohol users and their subsequent transition to dependence has varied from 2002 to 2019; the aggregated meta-analytic estimate is 1.7%. Females had a higher transition rate from initiation to dependence on alcohol within the first year than males. Individuals who are alcohol dependent drank more on average than newly initiated alcohol users. Once the confidence interval overlap is taken into account, there is no basis for claiming a female or a male excess in the occurrence of alcohol dependence soon after the onset of drinking when all ages are considered. The difference between the observed estimates of 1.5% and 1.9% is negligible once variances are considered. Finally, the changes made from DSM-IV to DSM-5 resulted in an increased estimate for individuals captured using the modified criteria for diagnosis. Directions for future research include different analyses on the transition estimates and using the estimates in the changes from DSM-IV to DSM-5 in a clinical setting to intervene in more alcohol disorder cases sooner, preventing serious complications and death.
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Title: ENGINEERING B. SUBTILIS TRANSCRIPTIONAL CONTROL AND PHYSIOLOGY FOR THE ADVANCEMENT OF BACTERIOTHERAPIES
Creator: Greeson, Emily Marilynn
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation explores to avenues of improvement for current bacteriotherapy approaches. Cody Madsen and I worked closely to advance engineered B. subtilis as a modular platform technology and Dr. Ashley Makela was instrumental in the in vivo studies (Chapter 2). In Chapter 2, transcriptional control of B. subtilis will demonstrate the ability to use magnetothermal energy generated by superparamagnetic iron oxide nanoparticles (SPIONs) and alternating magnetic fields (AMF) to induce...
Show moreThis dissertation explores to avenues of improvement for current bacteriotherapy approaches. Cody Madsen and I worked closely to advance engineered B. subtilis as a modular platform technology and Dr. Ashley Makela was instrumental in the in vivo studies (Chapter 2). In Chapter 2, transcriptional control of B. subtilis will demonstrate the ability to use magnetothermal energy generated by superparamagnetic iron oxide nanoparticles (SPIONs) and alternating magnetic fields (AMF) to induce temperature-sensitive repressors. Chapter 3 demonstrates how synthetic biology techniques can allow engineered B. subtilis to invade epithelial cells with the “zipper” mechanism. This was a collaborative effort as it was a multidisciplinary study and the contributions of Cody Madsen, Evran Ural, Dr. Ashley Makela, Dr. Bige Unluturk, and Victoria Toomajian were important and have been specifically noted in author contributions at the end of Chapter 3.Most patients on organ transplant waitlists will need alternative therapeutics due to a deficit of organ donations. Regenerative medicine approaches, including cellular reprogramming are being used to help address the deficit, but there are limitations. Bacteriotherapies aim to better deliver the therapeutics to a variety of targets, however, most approaches do so externally to the target cells. B. subtilis, a generally recognized as safe organism, engineered to express listeriolysin O (LLO) has been shown to replicate in the cytoplasm of macrophages and deliver transcription factors and modulate cell surface markers, cytokines, and chemokines. This mechanism of uptake only works with phagocytic cells creating an opportunity for the engineering of B. subtilis that targets internalization into non-phagocytic cells. When introducing known virulence factors into non-native organisms it is important to consider controlling the gene expression while trying to remain as minimally invasive as possible. Alternating magnetic fields (AMF) cause local temperature increases in regions with Superparamagnetic iron oxide nanoparticles (SPIONs), and we investigated the ability of this magnetic hyperthermia approach to regulate temperature-sensitive repressors (TSRs) in bacteria. Magnetic hyperthermia-based control of bacterial gene expression would advance development of bacteriotherapies and expand options of regulated bacterial transcription. TSRs block transcription in a temperature-dependent manner. B. subtilis was coated with three SPION variations, plain-dextran, amine- or carboxyl-coated and the interactions and AMF responses were characterized and induction of the TSRs was demonstrated using AMF. Murine intramuscular injections revealed continual association of SPIONs with B. subtilis. While there was no induction via AMF in vivo, pairing TSRs with magnetothermal energy using SPIONs for localized heating with AMF can lead to regional bacterial transcriptional control, a minimally invasive method that could be used with virulence factors and therapeutics. To delivery therapeutics to epithelial cells, B. subtilis llo was engineered to express internalin A (InlA), a protein native to Listeria monocytogenes. Internalin A is an adhesin that binds to the E-cadherin host cell receptor found in epithelial cells and mediates a “zipper” mechanism of invasion. B. subtilis llo inlA demonstrated cytosolic persistence and B. subtilis llo remained extracellular. Ultimately, the engineering of B. subtilis transcriptional control and physiology creates a new modular approach to regenerative medicine, cellular reprogramming, and cancer therapy that can be used in human health applications.
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Title: Accountability Through Programmatic Goods Distribution : The Ghanaian National Health Insurance Scheme
Creator: Anderson, Stephen Edward
Date: 2022
Collection: Electronic Theses & Dissertations
Description: One way in which political leaders gain support in democratic systems is by distributing goods to citizens. Theories of accountability suggest that when political authorities provide these goods to citizens, they will be rewarded. Yet, incumbents have at their disposal multiple mechanisms through which they can distribute goods to citizens. Generally, goods are either distributed through programmatic or non-programmatic means. This dissertation evaluates how the mechanism through which goods...
Show moreOne way in which political leaders gain support in democratic systems is by distributing goods to citizens. Theories of accountability suggest that when political authorities provide these goods to citizens, they will be rewarded. Yet, incumbents have at their disposal multiple mechanisms through which they can distribute goods to citizens. Generally, goods are either distributed through programmatic or non-programmatic means. This dissertation evaluates how the mechanism through which goods are distributed influences the ways in which citizens evaluate goods performance and political leaders. I address this question by focusing on the distribution of healthcare in the West African country of Ghana. I propose a theory to explain the process by which individuals reward or punish incumbent leaders for healthcare provision distributed via a national health insurance scheme (programmatic distribution) and targeted monetary transfers (non-programmatic distribution). The central insight proposed by the theory is that the characteristics of healthcare distribution via a national insurance scheme lead individuals to evaluate incumbent leaders based on the quality of goods they receive, while the nature of healthcare distribution through targeted transfers leads individuals to evaluate incumbents based not on the quality of goods they acquire, but on their receipt of a transfer. Interview and survey research accord with these propositions. I find that individuals are more likely to sanction incumbents for poor performance when low-quality healthcare goods are distributed through a national insurance scheme. When these same low-quality goods are acquired via monetary handouts, individuals are less likely to sanction incumbents for the quality of said goods. In the latter case, poor performance is not associated with the quality of healthcare goods acquired by citizens, but whether or not the necessary resources for the acquisition of these goods were dispensed by incumbents. I contribute to the literature on goods distribution and accountability and provide novel theory and evidence on the impact of programmatic distribution and incumbent support.
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Title: Investigating Cognition in Howard Engel's Memory Book : Literary Interventions and Intercessions in Scientific Models of Memory
Creator: Cave, Kylene N.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Crime fiction orbits around the concept of memory. At its core, crime narratives are concerned with reconstructing the past, bringing to light the events surrounding the criminal mystery. Memory also manifests in the genre’s detective figures, its modes of detection, and in the eyewitness testimonies used to solve the criminal mystery. In most crime narratives memory operates as a simplistic plot device used to temporarily complicate the mystery and, as such, it is rarely read beyond the...
Show moreCrime fiction orbits around the concept of memory. At its core, crime narratives are concerned with reconstructing the past, bringing to light the events surrounding the criminal mystery. Memory also manifests in the genre’s detective figures, its modes of detection, and in the eyewitness testimonies used to solve the criminal mystery. In most crime narratives memory operates as a simplistic plot device used to temporarily complicate the mystery and, as such, it is rarely read beyond the cursory scope of trauma. This dissertation, however, argues that crime narratives depicting extreme and rare cases of memory—like amnesia—help trace the boundaries around average functioning memory and reveal useful ways for conceptualizing how memory functions, and what disciplines have the impetus to do so. In this dissertation I argue that Howard Engel’s novel, Memory Book (2005), examines the complexities of memory by accomplishing three narratological tasks, distinguishing it from other crime fiction narratives and their more traditional handling of issues of memory and recall. The first task involves placing memory at the center of the narrative and elevating the mystery of the mind to the forefront of the plot. In placing memory at its center, the novel pushes back against traditional and widely popular scientific models of memory as merely the process of remembering and forgetting, advocating for a theory that is more complex and heterogenous. The second narratological task involves the novel’s ability to act as a literary intercessor on behalf of the sciences to translate and disseminate theories of memory to the layperson. Within this task, however, I assert that the novel not only passively intercedes, but actively intervenes in the study of memory by highlighting the inherent limitations of purely scientific or medical models of memory. In exposing these constraints, the novel also suggests a blended, transdisciplinary approach to conceptualizing human memory function and the mind. Lastly, the final task asserts that Memory Book is distinct because its narrative is infused with elements of lived experience, elements the scientific method is incapable of capturing in its probing of memory and cognition. Pointing specifically to Engel’s authorship and the circumstances surrounding the narrative’s composition following a stroke, I argue that the text intentionally blurs the boundaries between reality and fiction as a way of investigating the real-world implications of wrestling with memory loss and brain-injury based amnesia. Each of these narratological tasks is systematically analyzed by engaging with the Howard Engel’s memoir—The Man Who Forgot How to Read—deeply engaging with the novel’s paratextual elements, and through a detailed close reading of the novel.
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Title: USING NOVEL EXPERIMENTAL PROCEDURES TO ELICIT CONSUMER FOOD PREFERENCES AND DEMAND UNDER DIFFERENT CHOICE ENVIRONMENTS
Creator: Kilders, Valerie
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The food system is in a constant state of change driven by the social and bio-physical environment. Acknowledging the role that innovations and preference adaptations on the consumer side play in this process, in this dissertation I use cutting-edge experimental procedures to assess consumer demand in three areas: food-away-from-home (FAFH), sustainable food products, and new food technologies. In the first chapter I determine the impact dining settings have on consumer demand for FAFH, while...
Show moreThe food system is in a constant state of change driven by the social and bio-physical environment. Acknowledging the role that innovations and preference adaptations on the consumer side play in this process, in this dissertation I use cutting-edge experimental procedures to assess consumer demand in three areas: food-away-from-home (FAFH), sustainable food products, and new food technologies. In the first chapter I determine the impact dining settings have on consumer demand for FAFH, while also evaluating how a tax levied on red meat dishes would impact low- and high-income consumers. Capturing both substitution and complementarity patterns, I employ a food menu basket-based choice experiment approach, which permits respondents to freely pick and combine a range of food items at different price levels. I find that respondent’s orders in the delivery setting are typically higher in calories and most items act as complements for one another, while menu items are substitutes in the dine-in setting. The red meat tax that I simulate is regressive towards low-income individuals in the delivery setting but not in the dine-in setting. Thematically corresponding with the red meat tax, in the second chapter I study the market potential of “low carbon” ribeye steaks. In conjunction with this empirical component, I also propose the use of a reference price informed design that mirrors respondent’s price expectations for actual food shopping situations. I find the market potential of meat with a lower carbon footprint is relatively small, with conventional meat taking up most of the market share. Our results also show that a reference price informed design best describes choices and leads to more conservative market share estimates than traditional designs. One way to achieve a lower carbon footprint could be the use of gene-editing. In my third chapter, I therefore assess consumer preferences and willingness to pay (WTP) for milk from cows gene-edited to produce less methane. In doing so, I also analyze whether and how preferences for new food technologies are affected by information on the climate impact of dairy production. I supplement this analysis with an exploration of what medium of information (video vs. text) has the strongest impact on consumer acceptance and how responses change depending on whether respondents get to opt-in to seeing information or are forced to see the respective information. I find that gene-edited milk is discounted relative to other available alternatives. Results also show that choice outcomes differ between respondents seeking additional information and those remaining willfully ignorant. Giving respondents autonomy over their knowledge gathering is a significant factor in determining choice behavior. In sum, findings from these three chapters can be used to inform producers, policymakers, and the food industry, as well as improve the way food experiments are designed within the realm of food choices and beyond.
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Title: Lovecraft's Wake : Pessimism and Contemporary Weird Fiction
Creator: Conley, Richard Lance
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation examines select writings from H.P. Lovecraft and a group of contemporary authors of weird fiction in the context of a wake, a term defined in two precise ways. The first meaning of “wake” refers to an influential disturbance in the history of weird fiction left by Lovecraft’s writings, a seismic shift at the level of what the genre represents and the kinds of questions it asks. The second definition of “wake” refers to the fact that someone (or something) has passed, and we,...
Show moreThis dissertation examines select writings from H.P. Lovecraft and a group of contemporary authors of weird fiction in the context of a wake, a term defined in two precise ways. The first meaning of “wake” refers to an influential disturbance in the history of weird fiction left by Lovecraft’s writings, a seismic shift at the level of what the genre represents and the kinds of questions it asks. The second definition of “wake” refers to the fact that someone (or something) has passed, and we, the living, attend a wake to acknowledge this passing. With these two definitions in hand, the project argues that a group of contemporary weird fiction authors are writing in and at Lovecraft’s wake. Put differently, certain aspects of his fictional corpus have been revised by a group of contemporary weird fiction authors such that we can, on the one hand, acknowledge Lovecraft’s undeniable influence and the notion that to compose weird fiction in the present is to find one’s self always already writing in Lovecraft’s wake, and, on the other, to move beyond both some of the more dated questions his writing raises as well as the blatantly racist elements of some of his writing(s). Additionally, the contemporary weird authors examined in this project frame different manifestations of pessimism as a worldview that remains contingent, not on an indifferent cosmos, but on human communities in doomed worlds and the horrors that they inflict on each other in that context. In sum, the authors writing in and at Lovecraft’s wake want us not to combat the persistence of pessimism but rather to learn to accept it such that we can live with others in the fundamentally finite time allotted to each of us in a more peaceful way.
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Title: PERSUADING THROUGH FICTIONAL TELEVISION : A MIXED METHODS INVESTIGATION OF GENRE EXPECTATIONS
Creator: McClaran, Sharon-Nicole
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Genres provide an effective way for viewers to categorize, select, and evaluate entertainment television (TV) programs (Bilandzic & Rössler, 2004; Hawkins et al., 2001). People tend to know, for example, whether they will enjoy a medical drama or animated comedy based on their prior experience watching shows of that genre. Despite growing interest in entertainment media as a vehicle for persuasion, minimal research has considered how genre may influence receptivity to and acceptance of...
Show moreGenres provide an effective way for viewers to categorize, select, and evaluate entertainment television (TV) programs (Bilandzic & Rössler, 2004; Hawkins et al., 2001). People tend to know, for example, whether they will enjoy a medical drama or animated comedy based on their prior experience watching shows of that genre. Despite growing interest in entertainment media as a vehicle for persuasion, minimal research has considered how genre may influence receptivity to and acceptance of persuasive appeals in fictional TV programming (J. Cohen & Weimann, 2000; Grabe & Drew, 2007). Even less work has offered theoretical explanations for why genre may impact the persuasion process. Across three studies, this dissertation, guided by expectancy-violations theory (Burgoon, 1993, 2015), offers a thorough investigation into how audiences consider fictional TV genres and whether those expectations influence the success of subsequent persuasive attempts.In Study 1, qualitative interviews were conducted to gauge how viewers feel about using fictional TV shows for persuasion and whether genre is an influential factor in their assessments. The results provided preliminary evidence that viewers hold strong expectations for the likelihood and appropriateness of persuasive appeals in certain genres. In Study 2, persuasion-relevant expectations, including content credibility, learning potential, and likelihood of distributing an educational message, were tested for ten fictional TV genres (animated comedy, animated drama, comedy, crime comedy, crime drama, general drama, historical drama, medical comedy, medical drama, science-fiction/fantasy). Results of the online survey provided strong statistical support that viewers consider the content of TV genres differently and that these expectations influence hypothetical acceptance of an educational appeal. Lastly, Study 3 offered an experimental manipulation of genre (historical fiction vs. science- fiction/fantasy) to test whether genre expectation violations and message resistance explain the success of entertainment media in facilitating persuasion. Although the hypotheses were not supported in Study 3, post-hoc analyses found genre to influence participants’ perceived persuasive intent, which in turn, influenced attitudes, descriptive norms, and behavioral intention toward daily stretching. The cumulative results of this dissertation stress the importance of genre study in the entertainment media persuasion scholarship and offer several avenues for future research.
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Title: Development and Assessment of Predictive Models for Improved Swine Farming
Creator: Han, Junjie
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Prediction of outcomes is critical in both swine breeding and management. This necessitates the development of predictive models that address challenges in swine farming. For predictive modeling, there have been significant advances in deep learning. Nevertheless, there are needs to adapt deep learning-based models for specific swine farming problems including genomic prediction and behavior analysis. Furthermore, there is not yet a clear guideline on how to validate a model in this field....
Show morePrediction of outcomes is critical in both swine breeding and management. This necessitates the development of predictive models that address challenges in swine farming. For predictive modeling, there have been significant advances in deep learning. Nevertheless, there are needs to adapt deep learning-based models for specific swine farming problems including genomic prediction and behavior analysis. Furthermore, there is not yet a clear guideline on how to validate a model in this field. The overarching goal of this dissertation was to validate a collection of predictive models for improved swine farming with applications to precision management, phenotyping, and breeding. The first study addressed the pig genomic prediction problem. Differential evolution was utilized to optimize deep learning (DL) hyperparameters that affected the predictive performance of DL models. Performance of optimized DL was compared with “best practice” DL architectures selected from literature and baseline DL models with randomly specified hyperparameters. Optimized models showed clear improvement. Further, differential evolution saved considerable time compared to traditional optimization approaches e.g., grid search. Despite the success of genomic prediction, phenotyping has become a bottleneck in breeding programs as it is still time-consuming and labor-intensive. Computer vision (CV) can be used to automate the phenotyping process. Nonetheless, there are limited amount of public data for CV development in livestock farming. Most published CV applications to livestock farming were developed using rather small datasets, and their broader validity remained unknown. Therefore, the second study aimed at reviewing publicly available image datasets that were used for CV algorithms in livestock farming and the validation methods in the related work. Through the review, we could not find public datasets that addressed pigs’ agonistic behaviors (negative social behaviors), which is an important topic in swine farming. Given this, the third study aimed at collecting a video dataset to study pig’s agonistic behavior and adapting a state-of-the-art DL pipeline to classify pigs’ agonistic behaviors through video analysis. The pipeline was validated through various training-validation data partitions, where the training data were used for model development and the validation data were used for model evaluation. Results showed that splitting the training and validation sets at random led to over-optimistic estimates of model performance. The last study focused on developing and validating a statistical model for the analysis of pigs’ social interactions. Generalized linear mixed models were fitted, and a Bayesian framework was used for parameter estimation and posterior predictive model checking. The predictive performance of the models varied depending on the validation strategy, where three strategies were defined: random cross-validation, block-by-social-group cross-validation, and block-by-focal-animals validation. In conclusion, this dissertation provides information about how state-of-the-art models can be adapted for and validated in swine farming applications. Future directions of this research could aim at creating reference imagery datasets in swine farming that provides a platform for CV applications and developing integrated computer vision systems, which eventually assists in prediction tasks for improved pig management and breeding.
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Title: Assuming Ambiguity
Creator: Conklin, Rebecca C.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation considers ambiguity throughout the history of Rhetoric and Composition, a discipline generally concerned with clarity, concision, and correctness as key attributes of “good” writing. In the first part of this dissertation, I draw from the theoretical contributions made by Simone de Beauvoir in The Ethics of Ambiguity (1947) and show how the central tensions she wrestled with in that text mirror the tensions experienced at the dawn of this discipline, tensions that have (re...
Show moreThis dissertation considers ambiguity throughout the history of Rhetoric and Composition, a discipline generally concerned with clarity, concision, and correctness as key attributes of “good” writing. In the first part of this dissertation, I draw from the theoretical contributions made by Simone de Beauvoir in The Ethics of Ambiguity (1947) and show how the central tensions she wrestled with in that text mirror the tensions experienced at the dawn of this discipline, tensions that have (re)emerged throughout subsequent decades. I trace the disciplinary conversations in the decades following World War II, as Rhetoric and Composition sought to define itself and its space in increasingly neoliberal, corporate college and university structures. Summarizing field conversations around the problems of relevance, content/standards, teachers and students, and assessment, I show how the gap between disciplinary knowledge/best practices bumps up against the demands of a profit-driven university. This project offers another way of thinking and doing through a praxis of ambiguity, explored and articulated through five guiding verbs: imagine, emerge, expand, intuit, and situate. Through these guiding verbs, I explore how these verbs and the scholarship that supports them may offer ways to intentionally disrupt the presence of white supremacy culture in teaching, research, and administration in the discipline by making visible the characteristics of this culture and sketching the outlines of an interventional framework based on a praxis of ambiguity, offering avenues for future research.
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Title: Adaptation to agriculture in a serious crop weed, weedy radish (raphanus raphanistrum)
Creator: Garrison, Ava
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The colonization of novel environments requires organisms to shift their trait means in response to differing abiotic and biotic conditions in order to survive and persist. This response can be done via phenotypic plasticity (a trait shift in response to the environment), adaptation (a trait shift due to genetic change), or both strategies can be used together, with plasticity “buying time” for adaptation to occur. The colonization of novel environments is especially important to the...
Show moreThe colonization of novel environments requires organisms to shift their trait means in response to differing abiotic and biotic conditions in order to survive and persist. This response can be done via phenotypic plasticity (a trait shift in response to the environment), adaptation (a trait shift due to genetic change), or both strategies can be used together, with plasticity “buying time” for adaptation to occur. The colonization of novel environments is especially important to the establishment of agricultural weeds worldwide, which thrive in these extreme environments of intense competition and frequent disturbance. In this dissertation, I address the establishment and evolution of a harmful agricultural weed, weedy radish (Raphanus raphanistrum), as well as its divergence from a wild relative of the same species, the native radish ecotype. I first investigated the hypothesis of phenotypic plasticity “buying time” for adaptation to agricultural fields in weedy radish. Using growth chambers to simulate the ancestral (native) and derived (weedy) environments of weedy radish, I performed a reciprocal transplant with the weedy and native radish ecotypes. I found phenotypic plasticity between environments and genetic divergence between ecotypes to be equally common among traits, suggesting similar importance of plasticity and adaptation in weedy radish establishment. Further, in the majority of traits that were both plastic and differentiated between ecotypes, the direction of change matched, with the weedy environment producing phenotypic shifts in the direction of the weedy ecotype mean. This suggests plasticity in these traits may have enabled the subsequent adaptation and ecotype differentiation, supporting the buying-time hypothesis. Next, I explored the role of the plant hormone Gibberellic Acid (GA) in the evolution of weedy radish. Using exogenous application of GA both in the greenhouse and in weedy and native growth chamber environments, I found evidence that there has been an evolutionary change in the role of GA in trait expression between the two ecotypes. Namely, weedy radish is less responsive to GA application than native radish, suggesting either upregulation in GA production in weeds, or a lower level of GA required to enable gene expression in the weedy ecotype. This change in gene regulation by GA may have been important in the evolution of weedy radish in the agricultural field. Finally, I assessed the likelihood of weedy radish diverging from a native ancestor via adaptive evolution. I found that adaptive evolution was likely in the establishment of weedy radish due to increased fitness of the weedy ecotype compared to the native ecotype in the agricultural field. I also found traits under directional selection in the native ecotype, with the key takeaway that faster flowering is adaptive in the agricultural fields. I finally looked at the ability of weedy radish to evolve advanced flowering in the agricultural field via standing genetic variance by artificially selecting for early flowering in native radish. I found that in only two generations of selection, native populations significantly advanced their flowering time, supporting the notion of weedy radish rapidly adapting to agricultural conditions via standing genetic variation alone. Taken together, these findings work to piece together the evolutionary history of weedy radish, providing insight into its mechanisms of establishment. This work also contributes to our overall understanding of rapid evolution and phenotypic plasticity in the colonization of novel environments, in agricultural weeds and beyond.
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