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Title: The completion agenda and professional academic advisors at regional public universities
Creator: Smith-Tyge, Nathaniel
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "This qualitative study explored the experiences of professional academic advisors at three broad access regional public universities as they worked in the policy environment of the completion agenda. Employing a narrative inquiry approach through single-session semi-structured interviews, I gathered the stories of the nine participants about their professional experiences. This dissertation includes an in-depth discussion of the state of the completion agenda when the study was conducted....
Show more"This qualitative study explored the experiences of professional academic advisors at three broad access regional public universities as they worked in the policy environment of the completion agenda. Employing a narrative inquiry approach through single-session semi-structured interviews, I gathered the stories of the nine participants about their professional experiences. This dissertation includes an in-depth discussion of the state of the completion agenda when the study was conducted. The existing literature related to policy issues in higher education and academic advising is also presented. The study employs three theoretical frameworks to guide the analysis of the collected data. The first framework is the agency and structure theory as presented by Coburn et al. (2016). The second framework is based on the work of Cohen (1990) and is rooted in his foundational work on policy implementation from Mrs. Oublier's classroom. The final framework is the community of practice theory as presented by Coburn & Stein (2006). The key findings of this study are that the advisors lack agency in their professional roles and often times find themselves constrained by the structure and systems in their offices and universities. This manifests into three overarching themes that were found in the data. The first is that the participants are disconnected from the policy process at all levels. The frustration with this lack of agency leads to the second theme which is the advisors view themselves as student focused and not policy focused, which allows them to reclaim a level of professional agency. The third theme finds that often times the participants find themselves at odds with professional staff members in other departments on their campus that have different missions and purposes. Through the stories of the participants this study provides a context rich and empirical view of the experiences of academic advisors as they contend with the policy environment created by the completion agenda. The dissertation also provides implications for practice, research, theory, and policy. The key implication is the need for the involvement of advisors (and all student-facing professional staff) in the policy creation process at all levels. The advisors understand their work the best and should have a role in shaping the systems and structures that effect their ability to successfully work with students."--Pages ii-iii.
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Title: GOVERNANCE OF PEOPLE-CENTERED FOREST-AGRISCAPES RESTORATION IN MALAWI : INSTITUTIONAL AND MODELING APPROACHES
Creator: Djenontin, Ida Nadia Sedjro
Date: 2021
Collection: Electronic Theses & Dissertations
Description: This doctoral dissertation embodies an interdisciplinary inquiry of human-environment interactions approached from a geospatial perspective. It investigates some socio-institutional dimensions of ecosystem restoration, focusing on the Forest Landscape Restoration (FLR) paradigm. FLR is a people-centered ecosystem restoration approach that advances a holistic landscape approach to restoring degraded natural resources. FLR’s implicit landscape approach to environmental management requires...
Show moreThis doctoral dissertation embodies an interdisciplinary inquiry of human-environment interactions approached from a geospatial perspective. It investigates some socio-institutional dimensions of ecosystem restoration, focusing on the Forest Landscape Restoration (FLR) paradigm. FLR is a people-centered ecosystem restoration approach that advances a holistic landscape approach to restoring degraded natural resources. FLR’s implicit landscape approach to environmental management requires sectoral interactions and policy integration in implementing restoration interventions in interlocking agricultural and forested landscapes – forest-agriscapes. As such, FLR seeks to address, holistically, the interlinked challenges of land degradation, deforestation, biodiversity loss, climate change, livelihood insecurity, and unsustainable supply of multiple socio-ecological benefits. The research analyses specifically how to achieve integrated and sustainable governance of landscape-scale restoration of lands, trees, and forests by deepening understanding of the related institutional, socio-economic, cultural, and behavioral dimensions. It employs an analytical approach that blends qualitative analysis, econometric modeling, and spatial agent-based modeling (ABM) to explore forest-agriscapes restoration as a complex socio-ecological system (SES). Using Malawi as a country case study in sub-Saharan Africa (SSA), the research first investigates what potential context-appropriate governance system—including governance model, institutional arrangements, and regulatory framework—would adequately promote effective integrated implementation of landscape restoration. The research adopts a polycentric governance perspective based on the Ecology of Games Theory (EGT). Using the EGT, it explores the structural and functional dimensions of an appropriate integrated governance system by examining four specific governance parameters: collaboration arrangements, social learning mechanisms, coordination processes, and institutional externalities. Second, the research draws on an econometric perspective and an environmental behavior perspective rooted in social psychology to examine the local patterns and socio-cultural determinants and the decision-making processes of local individual and collective resources restoration efforts. Through a mixed qualitative and quantitative methods approach, it addresses why and how local smallholder farmers and resource users engage in restoration activities, including the driving and constraining factors for their restoration efforts. Finally, the research uses ABM, a bottom-up computational modeling approach to SES, to explore the aggregate landscape-level dynamic patterns and environmental impacts of local restoration decisions and consequent activities, with different simulations of management and policy scenarios. The research offers diverse knowledge contributions and practical insights for effective forest-agriscape restoration. It advances knowledge on framing ingredients of a contextualized polycentric governance system to successfully operationalize an integrated landscape approach to resources management and restoration in Malawi and contributes to testing the EGT as a novel theory of polycentric governance. Moreover, the research illuminates the nature, level, diversification features, and areal extent of local restoration, and uncovers associated main drivers and challenges. It also offers more social understanding of individual and collective restoration behaviors, notably insights on local farmers’ and resources users’ decision-making processes for land, tree, and forest restoration. This improves knowledge on empirically capturing such behavioral components and integrating them into computational modeling. Further, the research uncovers a forward-looking 10-year trend and spatially explicit patterns of potential restoration extent, intensification, participation level, and resulting landscape regreening. The dynamics of the potential aggregate environmental impacts of local, bottom-up restoration efforts suggest empowering them, shedding light on likely propitious management and policy options to operationalize. This contributes insights for spatially targeted and evidence-based restoration implementation in Malawi, exemplifying how to enhance the use of ABMs to support restoration management and policy. Overall, the research shows the promise of using mixed integrative research approaches to better inform effective FLR interventions and the practical insights for Malawi are also relevant for other similar SSA contexts. Broadly, the dissertation illustrates effective socio-ecological governance as one way to approach the persistent challenge centered on a complex co-existence issue: how to balance competing goals of attaining sustainable natural resource-based livelihoods, food security, and poverty reduction while protecting biodiversity and ecological integrity within a changing climate context.
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Title: HERITAGE AS A SOCIAL CONSTRUCT : AN EXPLORATORY STUDY OF HERITAGE DEFINITIONS, BENEFITS, AND PRACTICES AS PERCEIVED BY INDONESIAN KEY HERITAGE ACTORS
Creator: Patria, Teguh Amor
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Since 1987, conscious heritage conservation and heritage interpretation community groups have been proliferating in Indonesia. The emergence of these heritage groups has raised public awareness of heritage and heritage conservation in Indonesia. However, because conscious heritage work by Indonesians is a relatively recent phenomenon, limited scholarly attention had been paid to this field of study. Thus, there has been a need to explore heritage-related concepts and processes in the...
Show moreSince 1987, conscious heritage conservation and heritage interpretation community groups have been proliferating in Indonesia. The emergence of these heritage groups has raised public awareness of heritage and heritage conservation in Indonesia. However, because conscious heritage work by Indonesians is a relatively recent phenomenon, limited scholarly attention had been paid to this field of study. Thus, there has been a need to explore heritage-related concepts and processes in the Indonesian context. The purpose of this exploratory study is to begin to understand how Indonesian key actors working in conscious heritage conservation and interpretation define heritage, why conscious heritage conservation and interpretation are important, what motivates key actors, particularly as related to heritage benefits to individuals and society, how key actors practice their heritage work, and their recommendations for principles for how such work should be practiced. The study uses in-depth interviews of key actors, identified through purposive sampling. The study involved 11 respondents from two Indonesian cities, namely Bandung, representing Dutch colonial-built heritage, and Yogyakarta, a city with a strong Javanese culture, and representing two types of heritage work, heritage conservation and interpretation. Study findings suggest that key actors’ definitions of heritage have evolved over their lifespans and experiences. Current collective definitions of heritage consider it to 1) represent outstanding values of the past that are passed on and beneficial to the next generation; 2) be a complex, integrated system comprising diverse elements – including tangible and intangible, and cultural, natural, and spiritual elements that all interact; and 3) give a community identity and strength. Motivations of heritage workers are related to the perceived benefits of heritage that accrue to both individuals and society, and that include: financial benefits (personal and community); raised societal awareness of heritage and values; knowledge about local history and local wisdom; development of social skills, creation of local ambiance, place identity, and community pride; maintenance of living traditions and cultural aspects of social life; and improved societal wellbeing. Actual heritage practices include raising public awareness of heritage through varied activities such as disseminating heritage information to the public and organizing outreach programs for the public; conducting inventories of heritage resources; helping governments prepare policies vis-à-vis heritage conservation; using heritage as a modality to assist with redevelopment of communities after natural disasters; and developing local heritage-themed, community-based tour opportunities. Interviewees conveyed that heritage work could have been done more effectively in the past if the approach had been comprehensive and culturally appropriate, had involved diverse stakeholders within a community or society, conserved all integrated elements of heritage, and been based on local wisdom and histories. These principles are recommended for future heritage work.Study findings contribute to understanding perceptions of and work related to heritage, particularly from the Indonesian perspective; factors that influence these perceptions, including the strong role of spiritual values; the role of community-based heritage groups in conducting community-level heritage work; and the societal and individual benefits of heritage conservation and interpretation that motivate the work. Scholarly contributions include the role of specific concepts and theories as they influence perceptions of heritage and associated work, including broadly heritage as a social construct and, more specifically, interactions among people and place, place attachment, social exchange theory, collective memory, and roles of memory sites. Practical implications include providing a foundation for heritage-related government policies and regulations, insights into criteria for heritage conservation and interpretation priorities based on relevance and benefits to society and individuals, and contributions to effective heritage conservation and interpretation practices in Indonesia.
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Title: Data Integration in Population and Community Ecology using Hierarchical Modeling
Creator: Farr, Matthew T.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: In this dissertation, I develop and apply methods for data integration using hierarchical modeling to estimate the status, trends, and demography of wildlife populations and communities. I use multi-level statistical and mathematical models to explicitly link observed data to latent ecological processes. By separately modeling observational and ecological processes, I can integrate multiple disparate data sources into a unified framework to estimate ecologically relevant population and...
Show moreIn this dissertation, I develop and apply methods for data integration using hierarchical modeling to estimate the status, trends, and demography of wildlife populations and communities. I use multi-level statistical and mathematical models to explicitly link observed data to latent ecological processes. By separately modeling observational and ecological processes, I can integrate multiple disparate data sources into a unified framework to estimate ecologically relevant population and community parameters, often in the context of wildlife conservation. In Chapter One, I apply a multispecies hierarchical distance sampling model to assess the effect of management actions on a carnivore community in the Masai Mara National Reserve, Kenya. I assess variation in species-level responses to passive management, resulting in human disturbance and apex predator declines. In Chapter Two, I develop an integrated distribution model that uses distance sampling and presence-only data to jointly estimate species abundance. I apply this model to a case study on black-backed jackals (Canis mesomelas) to evaluate the effects of anthropogenic disturbance on the distribution of jackals across the Masai Mara National Reserve. In Chapter Three, I evaluate status and trends of species in a forest dwelling duiker community using detection-nondetection data. I develop a multispecies dynamic N-occupancy model to estimate species-level abundance, demographic parameters, and quasi-extinction probabilities. In Chapter Four, I create a spatiotemporal integrated model to estimate the effects of weather conditions on monarch butterflies (Danaus plexippus) during spring migration. Each chapter illustrates a unique application of data integration in wildlife ecology, either by combining data on multiple species to estimate population and community-level parameters or by combining disparate data sources on a single species to estimate demography and other population-level parameters. Data integration is a powerful framework that leverages all available information to address pressing conservation challenges.
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Title: IMPACTS OF DISTANT DRIVERS ON LANDSCAPES AND BIODIVERSITY
Creator: Hovis, Ciara Layne
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Global biodiversity is increasingly impacted by distant drivers. With societies more connected than ever before, natural resource consumption has expanded beyond administrative and political boundaries. International food trade in particular has profound impacts on land-use and socioeconomic and environmental outcomes. At the same time, global biodiversity is threatened at an unprecedented scale, with many of the causes obfuscated by complexities of distant, interacting socioecological...
Show moreGlobal biodiversity is increasingly impacted by distant drivers. With societies more connected than ever before, natural resource consumption has expanded beyond administrative and political boundaries. International food trade in particular has profound impacts on land-use and socioeconomic and environmental outcomes. At the same time, global biodiversity is threatened at an unprecedented scale, with many of the causes obfuscated by complexities of distant, interacting socioecological systems. Understanding the ultimate drivers of biodiversity change and translating them to local biodiversity outcomes is integral to addressing conservation challenges in the age of globalization. This dissertation analyzes the impacts of international trade on biodiversity in an agroecosystem undergoing land-use change driven by global markets. Chapter 1 provides background on the study region, Heilongjiang Province, and describes disruption of soybean production in the area due to changes in global trade. Chapter 2 is a systematic review of studies on distant drivers of biodiversity change. Across all taxa, harmful impacts on biodiversity were the most frequent outcome reported, with distant impacts of trade and tourism most frequently studied. In Chapter 3, satellite imagery was classified into landcover classes to create high-fidelity maps of the agriculture-dominated study landscape. By utilizing phenological, synthetic aperture radar, and vegetation/soil index data, accuracies of 91%- 80% were achieved. In Chapter 4 these landcover maps were used to calculate landscape metrics. These metrics were then used to analyze relationships between landscape structure (i.e., composition and configuration) and bird communities. Functional biodiversity indices derived from life history and morphological traits were examined in addition to taxonomic measures. Though no discernable differences between taxonomic and functional community metrics were observed, several significant relationships between landscape structure and biodiversity metrics were found. Crop diversity, natural landcover, and edge metrics, were positively correlated with bird richness. Aggregation of patches, corn area, and soybean area were negatively correlated. We also compared landscape structure and biodiversity between two regions impacted by global soybean trade. Despite the more impacted region having lower crop diversity and natural area, there was no difference in biodiversity between the two regions. The more impacted region also had more rice area, demonstrating that negative biodiversity impacts may be mitigated by rice cultivation. Chapter 5 built on the previous chapter by modeling bird occupancy to assess species-specific relationships with landscape structure. Results indicated that increased crop diversity significantly increased occupancy of birds at both the taxonomic and functional level, particularly for birds belonging to less common functional groups. Percentage of natural area was not as important as expected, while metrics related to landscape configuration had very few significant impacts on occupancy. Increases in rice area were not as detrimental to bird occupancy as increases in corn and soybean. In fact, soybean area exhibited more significant negative relationships with bird occurrence than corn, suggesting that decreases in soybean area due to global trade may have benefitted bird biodiversity in the case of a monocultural landscape. However, due to the prevalence of small-scale farming practices, the more likely outcome would be a decrease in crop diversity due to soybean fields being converted to more profitable crops (e.g., corn, rice). By linking global trade, changes in landcover/use, landscape structure, and local bird communities in the same context, the results of this dissertation highlight the need for integrated biodiversity studies that place ecosystems in the broader context of globalization.
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Title: A CASE STUDY EXPLORING HOW K-12 STUDENTS LEARN TO USE SOCIAL MEDIA FOR CIVIC GOOD
Creator: Askari, Emilia Shirin
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This case study explores what K-12 students learn from a 13-week class activity about attracting attention to civic issues on social media. This research responds to calls by scholars of civic education to expand notions of civic engagement and digital citizenship, which often have focused on urging students to protect their reputations in digital spaces. In contrast, the learning activity examined here encourages community-oriented digital citizenship, preparing students to inform and...
Show moreThis case study explores what K-12 students learn from a 13-week class activity about attracting attention to civic issues on social media. This research responds to calls by scholars of civic education to expand notions of civic engagement and digital citizenship, which often have focused on urging students to protect their reputations in digital spaces. In contrast, the learning activity examined here encourages community-oriented digital citizenship, preparing students to inform and possibly empower social change. This study is grounded in Cognitive Flexibility Theory, which focuses on learning in ill-structured domains such as public social media. Further, the study builds on the increasingly popular idea of the Fifth Estate, which posits that people acting in civic ways in public spaces can be a powerful check on government, playing a role similar to that of journalism institutions, sometimes referred to as the Fourth Estate. Data collected in this study included a pre-survey, a written reflection and post interviews with 4 students as well as artifacts such as social media posts. Students employed two main strategies to draw attention to civic issues on social media: audience-signaling and networking. Further, students learned to seek credible and diverse information using class accounts on TikTok, Instagram, and Twitter. Finally, students offered definitions of digital citizenship and shared thoughts about how schools should teach it via social media. This study fills a gap in the research literature about K-12 teaching with social media; few prior studies take advantage of social media’s affordance as a bridge between the classroom and communities outside the school. This study also illuminates learning as schools globally moved online in response to the pandemic.
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Title: Examining an Important Assumption in the Faultline Literature
Creator: Guo, Zhiya
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Group faultlines are defined as hypothetical dividing lines that split a team into subgroups based on the alignment of team members’ attributes. Prior faultline research has almost exclusively focused on the implications of between-subgroup relationships assuming that “team members form homophilous ties on either side of a faultline by associating with others in the team who have similar demographic attributes” (Ren et al., 2015, p. 390). However, this important assumption has not been tested...
Show moreGroup faultlines are defined as hypothetical dividing lines that split a team into subgroups based on the alignment of team members’ attributes. Prior faultline research has almost exclusively focused on the implications of between-subgroup relationships assuming that “team members form homophilous ties on either side of a faultline by associating with others in the team who have similar demographic attributes” (Ren et al., 2015, p. 390). However, this important assumption has not been tested. Drawing from social comparison theory and its “similarity hypothesis,” I argue that homogeneous, faultline-based subgroups may serve as a hotbed for social comparisons, and comparisons on social power can engender conflict under certain circumstances, triggering within-subgroup conflict. More specifically, consistent with the emerging research that recognizes different types of group faultlines, I outlined a) different dimensions that different faultline-based subgroups are more likely to compare and b) the downstream effects of these comparisons. Hypotheses were tested using multi-wave, round-robin data from multiple intact work teams of full-time employees. Results largely supported my predictions regarding knowledge-based subgroups but not so much for identity-based subgroups or resource-based subgroups. Implications and future directions are discussed.
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Title: PALETTEVIZ : A METHOD FOR VISUALIZATION OF HIGH-DIMENSIONAL PARETO-OPTIMAL FRONT AND ITS APPLICATIONS TO MULTI-CRITERIA DECISION MAKING AND ANALYSIS
Creator: Talukder, AKM Khaled Ahsan
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Visual representation of a many-objective Pareto-optimal front in four or more dimensional objective space requires a large number of data points. Moreover, choosing a single point from a large set even with certain preference information is problematic, as it imposes a large cognitive burden on the decision-makers. Therefore, many-objective optimization and decision-making practitioners have been interested in effective visualization methods to en- able them to filter down a large set to a...
Show moreVisual representation of a many-objective Pareto-optimal front in four or more dimensional objective space requires a large number of data points. Moreover, choosing a single point from a large set even with certain preference information is problematic, as it imposes a large cognitive burden on the decision-makers. Therefore, many-objective optimization and decision-making practitioners have been interested in effective visualization methods to en- able them to filter down a large set to a few critical points for further analysis. Most existing visualization methods are borrowed from other data analytics domains and they are too generic to be effective for many-criterion decision making. In this dissertation, we propose a visualization method, using star-coordinate and radial visualization plots, for effectively visualizing many-objective trade-off solutions. The proposed method respects some basic topological, geometric and functional decision-making properties of high-dimensional trade- off points mapped to a three-dimensional space. We call this method Palette Visualization (PaletteViz). We demonstrate the use of PaletteViz on a number of large-dimensional multi- objective optimization test problems and three real-world multi-objective problems, where one of them has 10 objective and 16 constraint functions. We also show the uses of NIMBUS and Pareto-Race concepts from canonical multi-criterion decision making and analysis literature and introduce them into PaletteViz to demonstrate the ease and advantage of the proposed method.
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Title: Dynamical Systems Analysis Using Topological Signal Processing
Creator: Myers, Audun
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Topological Signal Processing (TSP) is the study of time series data through the lens of Topological Data Analysis (TDA)—a process of analyzing data through its shape. This work focuses on developing novel TSP tools for the analysis of dynamical systems. A dynamical system is a term used to broadly refer to a system whose state changes in time. These systems are formally assumed to be a continuum of states whose values are real numbers. However, real-life measurements of these systems only...
Show moreTopological Signal Processing (TSP) is the study of time series data through the lens of Topological Data Analysis (TDA)—a process of analyzing data through its shape. This work focuses on developing novel TSP tools for the analysis of dynamical systems. A dynamical system is a term used to broadly refer to a system whose state changes in time. These systems are formally assumed to be a continuum of states whose values are real numbers. However, real-life measurements of these systems only provide finite information from which the underlying dynamics must be gleaned. This necessitates making conclusions on the continuous structure of a dynamical system using noisy finite samples or time series. The interest often lies in capturing qualitative changes in the system’s behavior known as a bifurcation through changes in the shape of the state space as one or more of the system parameters vary. Current literature on time series analysis aims to study this structure by searching for a lower-dimensional representation; however, the need for user-defined inputs, the sensitivity of these inputs to noise, and the expensive computational effort limit the usability of available knowledge especially for in-situ signal processing.This research aims to use and develop TSP tools to extract useful information about the underlying dynamical system's structure. The first research direction investigates the use of sublevel set persistence—a form of persistent homology from TDA—for signal processing with applications including parameter estimation of a damped oscillator and signal complexity measures to detect bifurcations. The second research direction applies TDA to complex networks to investigate how the topology of such complex networks corresponds to the state space structure. We show how TSP applied to complex networks can be used to detect changes in signal complexity including chaotic compared to periodic dynamics in a noise-contaminated signal. The last research direction focuses on the topological analysis of dynamical networks. A dynamical network is a graph whose vertices and edges have state values driven by a highly interconnected dynamical system. We show how zigzag persistence—a modification of persistent homology—can be used to understand the changing structure of such dynamical networks.
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Title: ASSESSING DISASTER MANAGEMENT EFFECTS ON RECOVERY OUTCOMES IN RURAL POST-DISASTER JAPAN
Creator: Ward, Kayleigh
Date: 2022
Collection: Electronic Theses & Dissertations
Description: As a country frequented by natural disasters, Japan has robust disaster management systems that can be employed quickly to mitigate human, environmental, and economic harm and losses. However, these systems tend to be most effective when handling small-scale localized disasters. In the face of the 2011 Great East Japan Earthquake which decimated the northeastern communities of the Tohoku region, Japan’s disaster management system collapsed, unable to handle such large scale and widespread...
Show moreAs a country frequented by natural disasters, Japan has robust disaster management systems that can be employed quickly to mitigate human, environmental, and economic harm and losses. However, these systems tend to be most effective when handling small-scale localized disasters. In the face of the 2011 Great East Japan Earthquake which decimated the northeastern communities of the Tohoku region, Japan’s disaster management system collapsed, unable to handle such large scale and widespread damage. In the ten years since the disaster many rural communities have contended with a variety of social and economic problems, often left unremedied despite on-going government intervention. In this context, this dissertation will explore the complex problems in Minamisanriku, Miyagi—a rural coastal community decimated by the 2011 Great East Japan Earthquake. By engaging and collaborating with organizations in this community, I assess the connections between disaster management and post-disaster recovery outcomes through various applications of social capital and power. I first investigate how historical legacies of national government policies influenced recovery outcomes in the Tohoku region and how have these processes influenced economic restructuring and social development in Minamisanriku during reconstruction. Next, I consider how governance structures within Miyagi prefecture influenced the social and economic development of Minamisanriku during reconstruction. Lastly, I look to how disaster management affects the ability of residents to handle locally-identified and in turn, how residents utilize their social capital to driver social and economic recovery. I assess several key ideas on the connections between forms and theories of social capital and how they affect long-term disaster recovery outcomes through the disaster management process. The dissertation is situated to improve our understanding of how social capital affects rural communities’ ability to respond to these troubles and to craft context specific solutions to them. It also offers a variety of policy recommendations about how to improve community-centered recovery within disaster management frameworks.
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Title: Supervised Dimension Reduction Techniques for High-Dimensional Data
Creator: Molho, Dylan
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The data sets arising in modern science and engineering are often extremely large, befitting the era of big data. But these data sets are not only large in the number of samples they have, they may also have a large number of features, placing each data point in a high-dimensional space.However, unique problems arise when the dimension of the data has the same or even greater order than the sample size. This scenario in statistics is known as the High Dimension, Low Sample Size problem (HDLSS...
Show moreThe data sets arising in modern science and engineering are often extremely large, befitting the era of big data. But these data sets are not only large in the number of samples they have, they may also have a large number of features, placing each data point in a high-dimensional space.However, unique problems arise when the dimension of the data has the same or even greater order than the sample size. This scenario in statistics is known as the High Dimension, Low Sample Size problem (HDLSS). In this paradigm, many standard statistical estimators are shown to perform sub-optimally and in some cases can not be computed at all. To overcome the barriers found in HDLSS scenarios, one must make additional assumptions on the data, either with explicit formulations or with implicit beliefs about the behavior of the data. The first type of research leads to structural assumptions placed on the probability model that generates the data, which allow for alterations to classical methods to yield theoretically optimal estimators for the chosen well-defined tasks. The second type of research, in contrast, makes general assumptions usually based on the the causal nature of chosen real-world data application, where the data is assumed to have dependencies between the parameters.This dissertation develops two novel algorithms that successfully operate in the paradigm of HDLSS. We first propose the Generalized Eigenvalue (GEV) estimator, a unified sparse projection regression framework for estimating generalized eigenvector problems.Unlike existing work, we reformulate a sequence of computationally intractable non-convex generalized Rayleigh quotient optimization problems into a computationally efficient simultaneous linear regression problem, padded with a sparse penalty to deal with high-dimensional predictors. We showcase the applications of our method by considering three iconic problems in statistics: the sliced inverse regression (SIR), linear discriminant analysis (LDA), and canonical correlation analysis (CCA). We show the reformulated linear regression problem is able to recover the same projection space obtained by the original generalized eigenvalue problem. Statistically, we establish the nonasymptotic error bounds for the proposed estimator in the applications of SIR and LDA, and prove these rates are minimax optimal. We present how the GEV is applied to the CCA problem, and adapt the method for a robust Huber-loss based formulation for noisy data. We test our framework on both synthetic and real datasets and demonstrate its superior performance compared with other state-of-the-art methods in high dimensional statistics. The second algorithm is the scJEGNN, a graphical neural network (GNN) tailored to the task of data integration for HDLSS single-cell sequencing data.We show that with its unique model, the GNN is able to leverage structural information of the biological data relations in order to perform a joint embedding of multiple modalities of single-cell gene expression data. The model is applied to data from the NeurIPS 2021 competition for Open Problems in Single-Cell Analysis, and we demonstrate that our model is able to outperform top teams from the joint embedding task.
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Title: PRENATAL CANNABIS EXPOSURE AMONG PREGNANT PEOPLE IN TWO MICHIGAN SAMPLES
Creator: Vanderziel, Alyssa
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation will address three study aims: Aim 1 will estimate the size of a suspected causal influence of prenatal cannabis exposure on a set of inter-related birth outcomes: birth size, gestational age, 5-minute Apgar score, and neonatal intensive care unit admission. Aim 2 will investigate the degree to which morning sickness might be associated with higher odds of cannabis use. Aim 3 is to conduct a feasibility study to assess the recruitment and retention of pregnant people who...
Show moreThis dissertation will address three study aims: Aim 1 will estimate the size of a suspected causal influence of prenatal cannabis exposure on a set of inter-related birth outcomes: birth size, gestational age, 5-minute Apgar score, and neonatal intensive care unit admission. Aim 2 will investigate the degree to which morning sickness might be associated with higher odds of cannabis use. Aim 3 is to conduct a feasibility study to assess the recruitment and retention of pregnant people who regularly use cannabis, measured by willingness to participate and complete the study survey; willingness to provide urine samples; the percentage of participants who are cannabis-only users; and the percentage of pregnant people retained for the three follow-up assessments. Aims 1 and 2 use data for the Michigan Archive for Research on Child Health, a prospective cohort of pregnant people recruited from 11 sites across Michigan between 2017 and 2021. Aim 1 and Aim 2 analytic sample sizes are n= 584 and n= 826, respectively. Results of Aim 1 suggest a modest but statistically significant association between prenatal cannabis exposure and birth size z-score after model adjustment for potential confounding variables (betamodel4= -0.3; 95% CI: -0.5, -0.003). Results of Aim 2 suggest higher odds of prenatal cannabis use with increasing morning sickness severity (ORmodel4= 1.2; 95% CI: 1.1, 1.2). Sensitivity analyses indicate higher odds of using cannabis during the first trimester with increasing morning sickness severity (ORmodel4= 1.1; 95% CI: 1.01, 1.2). Similarly, findings indicate higher odds of cannabis use in the second or third trimester of pregnancy with increasing morning sickness severity (ORmodel4= 1.2; 95% CI: 1.1, 1.4). Sensitivity analyses also suggest an association between pre-pregnancy and prenatal cannabis use and morning sickness severity (betamodel4= 0.1; 95% CI: 0.003, 0.2 and betamodel4= 0.2; 95% CI: 0.1, 0.2, respectively). For Aim 3, Cannabis Legalization in Michigan-Maternal & Infant Health, a prospective feasibility study, was designed to better understand the recruitment and retention of pregnant people who regularly use cannabis. The study recruited n= 77 baseline participants of which n= 15 were prospectively followed and assessed during each trimester of pregnancy and once post-delivery. Of the participants recruited at baseline, 42% reported using cannabis during pregnancy, of which 87% were cannabis-only users (i.e., no reported polysubstance use). All prospective participants were willing to provide urine samples; the concordance between self-reported cannabis use and urinalysis was 100% in the first and second trimesters and 92% in the third trimester of pregnancy. Study retention of the prospective sample was 80%; of n= 15 first trimester participants, n= 3 were loss-to-follow-up. Of the remaining 12 participants, 83% had complete data across all four timepoints.Findings from this dissertation reveal that pregnant people are willing to participate in a study that explores the health effects of prenatal cannabis use on birth outcomes and maternal health. Larger studies are warranted to assess the association between prenatal cannabis exposure and fetal growth and development, as well as the relationship between morning sickness and cannabis use. This dissertation also detected an association between prenatal cannabis exposure and lower birth size, suggesting that pregnant people, or people contemplating pregnancy, should be cautioned against using cannabis until more studies are conducted to establish causality between prenatal cannabis use and neonatal health.
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Title: SCATTERING AMPLITUDES FOR ZZ PRODUCTION AT THE LHC AND TOP-QUARK MASS EFFECTS
Creator: Agarwal, Bakul
Date: 2022
Collection: Electronic Theses & Dissertations
Description: With the Large Hadron Collider providing experimental data with unprecedented precision, theoretical predictions must improve similarly to keep up.Among a plethora of processes being studied at the LHC, the production of a pair of vector bosons is of particular importance. Consequently, precise theoretical predictions for these processes are necessary. This thesis discusses primarily the calculation of ZZ production through gluon fusion at 2-loops with full top-quark mass dependence as well...
Show moreWith the Large Hadron Collider providing experimental data with unprecedented precision, theoretical predictions must improve similarly to keep up.Among a plethora of processes being studied at the LHC, the production of a pair of vector bosons is of particular importance. Consequently, precise theoretical predictions for these processes are necessary. This thesis discusses primarily the calculation of ZZ production through gluon fusion at 2-loops with full top-quark mass dependence as well as the technological improvements required to successfully perform the calculation. Also discussed briefly is the quark initiated production of $\gamma\gamma + \text{jet}$ at 2-loops where some of these technologies allowed to overcome prior bottlenecks in the calculation of the helicity amplitudes.The 2-loop corrections for ZZ production through massless quarks had been known; in this work, the 2-loop corrections through the massive top quark are calculated .To achieve this, a new algorithm to systematically construct linear combinations of integrals with a convergent parametric integral representation is developed. This algorithm finds linear combinations of general integrals with numerators, dots, and dimension shifts as well as integrals from subsectors.To express the amplitudes in terms of these integrals, Integration-By-Parts (IBP) reduction is performed making use of syzygies and finite field based methods.A new algorithm is employed to construct these syzygies using linear algebra. The IBP reductions for $gg\rightarrow ZZ$ are successfully performed using these techniques. Further improvements, including predetermining the structure of the coefficients in IBP reductions, are used to successfully perform the reductions for $\gamma\gamma + jet$. Multivariate partial fractioning is used to simplify the final expressions to more manageable forms and render them suitable for fast numerical evaluation.%\thispagestyle{empty}In the case of $gg\rightarrow ZZ$, due to the presence of structures beyond polylogarithms, sector decomposition is employed to numerically evaluate the finite master integrals.Evaluating the amplitudes, agreement is found with previously calculated expansions specifically in the limit of large and small top mass. Improved results are presented for scattering at intermediate energies and/or for non-central scattering angles. With this calculation, the last building block required for the calculation of the full NLO cross-section for $gg\rightarrow ZZ$ is known.
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Title: Cultural adaptation of the transitioning together® program for caregivers of adolescents with autism in Accra, Ghana
Creator: Ami-Narh, Danielle Dede
Date: 2019
Collection: Electronic Theses & Dissertations
Description: For adolescents with autism and their families, transitioning to adulthood often means overcoming several social, systemic and environmental barriers (Lehman et al., 2002). In Ghana, misconceptions, limited knowledge and non-categorization of autism have contributed to delays in early detection, diagnosis, treatment and unavailability of supports for individuals and their families, which are three essential components for optimal outcomes (Danquah-Brobbey, 2018). These barriers put strenuous...
Show moreFor adolescents with autism and their families, transitioning to adulthood often means overcoming several social, systemic and environmental barriers (Lehman et al., 2002). In Ghana, misconceptions, limited knowledge and non-categorization of autism have contributed to delays in early detection, diagnosis, treatment and unavailability of supports for individuals and their families, which are three essential components for optimal outcomes (Danquah-Brobbey, 2018). These barriers put strenuous pressure on the caregivers who have found themselves at the center of their child's transition planning process.The purpose of this study is to address a service gap for Ghanaian families and their adolescent children with autism by culturally adapting an existing evidence-based program, Transitioning Together® (Smith, Greenberg, & Mailick, 2012). Specifically, the researcher sought to develop a set of culturally appropriate program curriculum modules, that address the suitable demographics and unique caregiving needs of families of adolescents with autism in Ghana. This study was designed to explore the central research question: What changes need to be made to the Transitioning Together® program for Ghanaian caregivers, to increase its cultural relevance, content applicability, and user-friendliness?The researcher developed a methodological framework using the Cultural Adaptation Process Model (CAPM) (Domenech- Rodriguez & Weiling, 2004) and the Ecological Validity Framework (EVF) (Bernal, Bonilla, & Bellido, 1995) in a Participatory Action Research. This methodology included focus group discussions with practitioners and individual interviews with eight caregivers to provide input on what and how they want the program to be presented. In adapting the Transitioning Together® program, content changes were integrated throughout the program instead of simply adding cultural factors to individual sessions. Changes were made to the program manual to reflect the length of the program, questions for discussion, appropriate goals for caregivers and medium of communication for facilitators and caregivers. A methodical review with nine experts to review and provide feedback on the developed program was solicited after changes were made.The results of this study show that caregivers and practitioners in Ghana will benefit from the program if implemented seamlessly. Additionally, Transitioning with Autism, Growing Up, Autism and Family and, Behavior Management are the specific topics caregivers deemed important and beneficial to discuss during group sessions. Implications for practice, policy, and future research are discussed.
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Title: THE EFFECT OF CLAW REMOVAL METHODS AND TEMPERATURE ON THE POST-RELEASE SURVIVAL AND CRITICAL THERMAL MAXIMUM OF STONE CRAB (MENIPPE MERCENARIA)
Creator: Walus, Alexandria Marie
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Florida stone crab (Menippe mercenaria) is an emerging commercial fishery in the Bahamas with its main export to the United States of America. This fishery capitalizes on the oversized claws of the crab, which are harvested, before the crab is returned to the sea where it can potentially regrow its claws. While it is often assumed that the crab will regrow its claws and re-enter the fishery, only 13% of harvested crabs in the fishery have regrown claws, and an estimated 2-81% of crabs survive...
Show moreFlorida stone crab (Menippe mercenaria) is an emerging commercial fishery in the Bahamas with its main export to the United States of America. This fishery capitalizes on the oversized claws of the crab, which are harvested, before the crab is returned to the sea where it can potentially regrow its claws. While it is often assumed that the crab will regrow its claws and re-enter the fishery, only 13% of harvested crabs in the fishery have regrown claws, and an estimated 2-81% of crabs survive post-claw removal and release. In addition, the Caribbean region is considered one of the most vulnerable areas with respect to climate change. Therefore, because most aquatic organisms cannot regulate their body temperature, they are directly influenced by environmental temperature stress, and when combined with the stress of claw removal may further decrease the capacity of the crab to survive warming temperatures. The purpose of my thesis was to: 1) determine a method of claw removal that maximizes survival for stone crab, 2) determine the effect of rapidly warming water temperatures on the reflex behavior of crabs post-release, and 3) determine the effect of claw removal on the critical thermal maximum (CTMax) of stone crab. In chapter 1, I used a controlled laboratory experiment to compare a new autotomy-inducing technique to the typical method of claw removal. For the two different claw removal methods, I compared the survival and start time for claw regeneration as a function of harvester experience and whether one claw or both claws were removed. Finally, the claws that were removed were inspected by independent observers to determine whether any differences using the two methods could be identified. Overall, I found that crabs with claws removed using the proposed induced autotomy method had significantly higher survival than crabs with claws removed using the typical method, while crabs with claws removed by inexperienced harvesters had the lowest. In Chapter 2, I conducted a series of laboratory experiments to measure nine reflex action mortality predictor reflexes of crabs and determine the critical thermal maximum (CTMax) for stone crab that had one or two claws removed using induced-autotomy. Of the nine reflexes used to develop an endpoint necessary for calculating CTMax, three were determined to be suitable (equilibrium, mouth closure and appendage turgor) and CTMax was 37.6 °C, and independent of the number of claws removed using the proposed induced-autotomy method. Overall, the tool required to conduct the induced-autotomy method of claw removal is simple and easily purchased or constructed and can easily be taught to recreational and commercial harvesters as a way to improve survival and thus sustainability of this important fishery.
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Title: PRETERM DELIVERY AND ITS ASSOCIATION WITH FALSE POSITIVE, AUDITORY BRAINSTEM RESPONSE (ABR)-BASED NEWBORN HEARING SCREENING FINDINGS
Creator: Rathore, Mandavni
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Newborn hearing screening failure can occur in infants without hearing loss; these false-positive (FP) results have been speculated to reflect neurodevelopmental disorder risk. Preterm birth (PTB), a known neurodevelopmental risk factor, has been associated with FP at initial screening. We aim to further characterize this association by stratifying PTB by gestational age and delivery circumstance. To do this, we analyzed birth certificate and Early Hearing Detection & Intervention data from...
Show moreNewborn hearing screening failure can occur in infants without hearing loss; these false-positive (FP) results have been speculated to reflect neurodevelopmental disorder risk. Preterm birth (PTB), a known neurodevelopmental risk factor, has been associated with FP at initial screening. We aim to further characterize this association by stratifying PTB by gestational age and delivery circumstance. To do this, we analyzed birth certificate and Early Hearing Detection & Intervention data from the Michigan Dept. of Health & Human Services (2007–2015; n = 919,363). We restricted our analysis to singleton live births with available ABR-based hearing screening data and obstetric estimates of gestational age (n = 655,079). We then used logistic regression to evaluate the association of PTB defined by gestational age (extreme: < 28 weeks; moderate: 28–34 weeks; late: 34–36 weeks) and delivery circumstance (spontaneous, medically indicated) with FP, using full-term birth (≥ 37 weeks) as the referent group. Approximately 4% of infants had FP findings. All gestational age categories were associated with this phenomenon (extreme: OR = 4.2, 95% CI 3.7, 4.7; moderate: OR = 1.2, 95% CI 1.1, 1.3; late: 1.6, 95% CI 1.5, 1.7). Spontaneous and medically indicated PTB were also associated with FP (OR = 1.7, 95% CI 1.6, 1.8; OR = 1.4, 95% CI 1.3, 1.5, respectively). All results persisted following adjustment for socio-demographic and antepartum factors except for moderate PTB (OR = 1.0, 95% CI 0.9, 1.1), though sensitivity analyses suggested marked heterogeneity within this group. Further research is needed to investigate factors underlying these differences and whether they correlate with neurodevelopmental disorder diagnoses.
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Title: DESIGN AND ENGINEERING OF STARCH-BASED POLYMER MATERIALS AS SUBSTITUTES FOR PERSISTENT NON-BIODEGRADABLE PLASTICS
Creator: Kulkarni, Apoorva Chandrakant
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Replacing carbon-carbon backbone persistent hydrocarbon plastics with biobased and biodegradable plastics offers value proposition of reduced carbon footprint and an environmentally responsible end-of-life. This work focuses on design and engineering of starch based polymeric materials as substitutes for non-biodegradable plastics. The biodegradability of these bioplastics in aqueous environment was evaluated.Starch foams are being used as replacement for petroleum-based foams in insulation...
Show moreReplacing carbon-carbon backbone persistent hydrocarbon plastics with biobased and biodegradable plastics offers value proposition of reduced carbon footprint and an environmentally responsible end-of-life. This work focuses on design and engineering of starch based polymeric materials as substitutes for non-biodegradable plastics. The biodegradability of these bioplastics in aqueous environment was evaluated.Starch foams are being used as replacement for petroleum-based foams in insulation and cushion protection applications. However, moisture sensitivity remains a problem resulting in collapse of cell structure and loss of mechanical integrity. First section of the thesis focuses on engineering high-performance starch foams with enhanced moisture resistance using reactive extrusion processing technology. Chitosan, polyvinyl butyral (PVB) and sodium trimetaphosphate (STMP) were used with water as a plasticizer and a blowing agent to make foams with desired physico-mechanical properties. The resulting foams were hydrophobic, insoluble in water, and showed improved moisture resistance. The biodegradability of the foams was not impacted – they were completely biodegradable as established by ASTM/ISO standards. Crosslinking of starch with STMP increased the compressive strength of the foams by three times compared to control foams. Optimization of process parameters ensured an efficient, cost-effective route towards commercialization. In the second section, our group’s chemically modified thermoplastic starch (MTPS) prepared by reactive extrusion technology was explored in three different applications. First, MTPS, was melt blended with glycol modified polyethylene terephthalate (PETG) using transesterification chemistry to synthesize MTPS-g-PETG in situ graft copolymer with 33% grafting. Mechanical and thermal properties of the blend were evaluated and compared with neat PETG. The addition of starch into PETG molecular backbone did not result in PETG biodegradability. This finding refutes many claims of biodegradability of non-biodegradable polymers by the addition of starch and similar additives. in the marketplace. Second, the use of MTPS as a biobased and biodegradable nucleating agent and barrier property enhancer in polylactide (PLA) was explored. Our findings establish that MTPS accelerates the rate of crystallization of PLA (polylactide polymers) by up to 98 times at 100°C, reducing the half time for crystallization from 20 mins to less than 1 minute. Oxygen barrier properties of PLA was improved 127% without causing detrimental impact on mechanical properties or biodegradability. Third application focuses on using MTPS as a carrier for iodine, which is a very effective and strong antimicrobial agent. The antimicrobial starch-iodine complex in pellet form was manufactured by extrusion processing. The new MTPS-iodine complex was incorporated in various proportions to commercial fully biodegradable-compostable polyester films. The morphological, mechanical, and antibacterial properties of these films were evaluated and compared with current commercial additives used to obtain antibacterial properties. The last section focuses on the end-of-life evaluations for biobased and biodegradable plastics using kinetics approach. The effect of temperature on biodegradation of cellulose and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in an aqueous environment seeded with a biologically aggressive microbial inoculum was studied. A global equation was derived from the reparametrized Arrhenius equation and the kinetic rate law to estimate the time required for 90% removal of polymer from the low temperature ocean environment. The t90 (time required to remove 90% of the polymer carbon from the environment) for PHBV at 10°C ranged from 6.2-6.9 years. The t90 of cellulose at 10 C was found to be 1.1-1.2 years. ASTM/ISO standards for measuring and reporting ocean biodegradability is static and conducted at one temperature (30°C), whereas ocean temperatures can vary from −1.8 °C to 33.4 °C. The kinetic analysis and model developed can provide a method to estimate time for complete removal of the biodegradable polymer carbon in ocean environments.
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Title: Improving the Efficiency of Residential Buildings in Rural Alaska : An Analysis of Existing Infrastructure and Its Importance in Creating Energy-Efficient Homes
Creator: Milan, Maria
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Rural communities in Alaska, many of which have a high Alaska Native population, currently face significant housing challenges. In a climate that can become extremely cold, houses are generally lacking in energy efficiency. Residents pay high rates for both oil and electricity to heat and operate their homes. Their homes are much smaller and with higher occupancy in comparison to typical U.S. homes. In addition, as the winter season brings sub-zero temperatures, windows remain shut with...
Show moreRural communities in Alaska, many of which have a high Alaska Native population, currently face significant housing challenges. In a climate that can become extremely cold, houses are generally lacking in energy efficiency. Residents pay high rates for both oil and electricity to heat and operate their homes. Their homes are much smaller and with higher occupancy in comparison to typical U.S. homes. In addition, as the winter season brings sub-zero temperatures, windows remain shut with limited mechanical or natural ventilation, also creating indoor air quality concerns. To date there has been limited studies of rural Alaskan communities’ housing, to better understand and quantify such housing challenges. This research focuses on a detailed study of the rural Alaskan community of Unalakleet. Located on the western shore of Alaska, this coastal community of approximately 765 people faces many housing challenges, similar to other rural Alaskan communities. Through collaboration with the housing authority in Unalakleet, this research conducted home energy assessments and resident interviews in the summer of 2021, including 27 energy assessments and 22 interviews. The purpose of the energy assessments was to collect information on typical building features and data, as well as to identify housing challenges. The interviews were generally completed for homes that also had an energy assessment and were used to better understand residents’ perspectives on energy and housing challenges beyond what was observed in the assessments. Blower door tests suggest that homes are usually small and tight, with leakiness around areas like the windows, where mold frequently was observed. Short-term indoor air quality monitoring suggests that some homes, especially those less than 46 m2 , had high CO2 concentrations, relative to others. Some homes had significant mold growth, and others had many areas of damage. Still, interviews with community members suggest that they were grateful for their housing and the ability to live in Unalakleet. The overall purpose of this research is to provide evidence to quantify the typical housing characteristics presence in rural Alaskan communities, as well as to provide results that motivate and support opportunities for new, more efficient housing. The introduction discusses major housing challenges, from high energy bills to the history of inefficient infrastructure in rural Alaska. Physical characteristics of assessed homes, followed by indoor air quality and air flow, are discussed in Chapters 2 and 3, respectively. Finally, Chapter 4 uses data collected from the 27 housing assessments to create a building energy model, where energy usage in existing housing is modeled to represent a ‘typical’ rural Alaskan home. The results of this model show where the largest improvements in efficiency can be made, especially in adding higher R-value insulation. The conclusion provides a brief overview of research contribution, limitations, and future work.
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Title: Optimizing and Improving the Fidelity of Reactive, Polarizable Molecular Dynamics Simulations on Modern High Performance Computing Architectures
Creator: O'Hearn, Kurt A.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Reactive, polarizable molecular dynamics simulations are a crucial tool for the high-fidelity study of large systems with chemical reactions. In support of this, several approaches have been employed with varying degrees of computational cost and physical accuracy. One of the more successful approaches in recent years, the reactive force field (ReaxFF) model, wasdesigned to fill the gap between traditional classical models and quantum mechanical models by incorporating a dynamic bond order...
Show moreReactive, polarizable molecular dynamics simulations are a crucial tool for the high-fidelity study of large systems with chemical reactions. In support of this, several approaches have been employed with varying degrees of computational cost and physical accuracy. One of the more successful approaches in recent years, the reactive force field (ReaxFF) model, wasdesigned to fill the gap between traditional classical models and quantum mechanical models by incorporating a dynamic bond order potential term. When coupling ReaxFF with dynamic global charges models for electrostatics, special considerations are necessary for obtaining highly performant implementations, especially on modern high-performance computing architectures.In this work, we detail the performance optimization of the PuReMD (PuReMD Reactive Molecular Dynamics) software package, an open-source, GPLv3-licensed implementation of ReaxFF coupled with dynamic charge models. We begin byexploring the tuning of the iterative Krylov linear solvers underpinning the global charge models in a shared-memory parallel context using OpenMP, with the explicit goal of minimizing the mean combined preconditioner and solver time. We found that with appropriate solver tuning, significant speedups and scalability improvements were observed. Following these successes, we extend these approaches to the solvers in the distributed-memory MPI implementation of PuReMD, as well as broaden the scope of optimization to other portions of the ReaxFF potential such as the bond order computations. Here again we find that sizable performance gains were achieved for large simulations numbering in the hundreds of thousands of atoms.With these performance improvements in hand, we next change focus to another important use of PuReMD -- the development of ReaxFF force fields for new materials. The high fidelity inherent in ReaxFF simulations for different chemistries oftentimes comes at the expense of a steep learning curve for parameter optimization, due in part to complexities in the high dimensional parameter space and due in part to the necessity of deep domain knowledge of how to adequately control the ReaxFF functional forms. To diagnose and combat these issues, a study was undertaken to optimize parameters for Li-O systems using the OGOLEM genetic algorithms framework coupled with a modified shared-memory version of PuReMD. We found that with careful training set design, sufficient optimization control with tuned genetic algorithms, and improved polarizability through enhanced charge model use, higher accuracy was achieved in simulations involving ductile fracture behavior, a difficult phenomena to hereto model correctly.Finally, we return to performance optimization for the GPU-accelerated distributed-memory PuReMD codebase. Modern supercomputers have recently achieved exascale levels of peak arithmetic rates due in large part to the design decision to incorporate massive numbers of GPUs. In order to take advantage of such computing systems, the MPI+CUDA version of PuReMD was re-designed and benchmarked on modern NVIDIA Tesla GPUs. Performance on-par with or exceeding the LAMMPS Kokkos, a ReaxFF implementation developed at Scandia National Laboratories, with PuReMD typically out-performing LAMMPS Kokkos at larger scales.
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Title: VISIONING THE AGRICULTURE BLOCKCHAIN : THE ROLE AND RISE OF BLOCKCHAIN IN THE COMMERCIAL POULTRY INDUSTRY
Creator: Fennell, Chris
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Blockchain is an emerging technology that is being explored by technologists and industry leaders as a way to revolutionize the agriculture supply chain. The problem is that human and ecological insights are needed to understand the complexities of how blockchain could fulfill these visions. In this work, I assert how the blockchain's promising vision of traceability, immutability and distributed properties presents advancements and challenges to rural farming. This work wrestles with the...
Show moreBlockchain is an emerging technology that is being explored by technologists and industry leaders as a way to revolutionize the agriculture supply chain. The problem is that human and ecological insights are needed to understand the complexities of how blockchain could fulfill these visions. In this work, I assert how the blockchain's promising vision of traceability, immutability and distributed properties presents advancements and challenges to rural farming. This work wrestles with the more subtle ways the blockchain technology would be integrated into the existing infrastructure. Through interviews and participatory design workshops, I talked with an expansive set of stakeholders including Amish farmers, contract growers, senior leadership and field supervisors. This research illuminates that commercial poultry farming is such a complex and diffuse system that any overhaul of its core infrastructure will be difficult to ``roll back'' once blockchain is ``rolled out.'' Through an HCI and sociotechnical system perspective, drawing particular insights from Science and Technology Studies theories of infrastructure and breakdown, this dissertation asserts three main concerns. First, this dissertation uncovers the dominant narratives on the farm around revision and ``roll back'' of blockchain, connecting to theories of version control from computer science. Second, this work uncovers that a core concern of the poultry supply chain is death and I reveal the sociotechnical and material implications for the integration of blockchain. Finally, this dissertation discusses the meaning of ``security’’ for the poultry supply chain in which biosecurity is prioritized over cybersecurity and how blockchain impacts these concerns. Together these findings point to significant implications for designers of blockchain infrastructure and how rural workers will integrate the technology into the supply chain.
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