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Title: ACHIEVING A LONG-LIVED CHARGE-SEPARATED FE(II) CHROMOPHORE : INSIGHTS INTO THE ROLE OF REORGANIZATION ENERGY ON THE ULTRAFAST PHOTOPHYSICAL PROCESSES OF D6 POLYPYRIDYL COMPLEXES
Creator: Carey, Monica Catherine
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Photoredox catalysis reactions are ubiquitous in nature. These processes require a long-lived charge-separated state that is ideally suited for redox-based chemistry and photovoltaic applications. Many common chromophores used in these systems are ruthenium(II)-based, but the low earth abundance of this metal makes it non-viable for large-scale applications in the long-term. The first row congener of Ru(II) is iron(II), but its decreased ligand field strength relative to the second row...
Show morePhotoredox catalysis reactions are ubiquitous in nature. These processes require a long-lived charge-separated state that is ideally suited for redox-based chemistry and photovoltaic applications. Many common chromophores used in these systems are ruthenium(II)-based, but the low earth abundance of this metal makes it non-viable for large-scale applications in the long-term. The first row congener of Ru(II) is iron(II), but its decreased ligand field strength relative to the second row transition metal causes the metal-to-ligand charge transfer (MLCT) excited state to be depopulated on an ultrafast timescale, deactivating into metal-centered ligand field (LF) excited states that are inefficient for photovoltaic applications. The aim of this work is to understand the fundamental differences in the photophysical processes of Ru(II) and Fe(II) analogues. Three strategies can be envisioned for prolonging the MLCT lifetime in Fe(II) complexes: (1) prohibiting the vibrational modes associated with the MLCT→LF transition with synthetic modifications to the ligand, (2) increasing the ligand field strength to tune the LF and MLCT states such that the potential energy surface diagram for Fe(II) resembles that of Ru(II), or (3) extending conjugation within the ligand away from the metal center, thereby decoupling the MLCT and LF excited states. Any one of these approaches will inherently affect the reorganization energy, or the amount of energy required for the reactants to undergo vibrational and nuclear motions in order to achieve the geometry of the products without any electron transfer or electronic state crossing occurring. Variable-temperature transient absorption (VT-TA) spectroscopy is a methodology that has been developed to initially study the ground state recovery (GSR) processes of some low-spin Fe(II) polypyridyl complexes. Arrhenius parameters for this class of compounds are found experimentally for the first time and from these data, semi-classical Marcus theory analysis is performed, allowing for inner-sphere (i.e., complex-only) reorganization energies to be found for each. The Hab4/λ ratio is determined to be different between bis-tridentate and tris-bidentate species, which is postulated to imply a difference in nuclear coordinate for the relaxation process. The VT-TA methodology is also applied to a bis-tridentate compound for which GSR is both nearly barrierless and nearly at the crossing-point of the 5T2/3T1 as the lowest-energy excited state. The outer-sphere reorganization energy is adjusted through the use of counteranions and solvents in an attempt to tune the barrierless nature of the complex. The identity of the solvent did appear to affect the reorganization energy and the inverted region may have been accessed. The solvation dynamics of the vibrational cooling process in a Ru(II) chromophore were studied as a function of excitation wavelength in a series of alcohol and nitrile solvents. A dual solvation mechanism was observed depending on the amount of excess energy given to the system. Through the use of a sterically-encumbered analogue, the large aryl rotation in the MLCT excited state was determined to be the relevant nuclear coordinate in the vibrational cooling process as it related to the solvation. The Fe(II) analogue of this complex has also been prepared and studied in order to draw direct comparisons of the photophysical processes of these two related systems. These analogues are based on ligands with extended conjugation. In order to study the effects of delocalization on the excited state lifetime, other compounds of this type have been prepared and preliminary measurements of the MLCT lifetimes indicate that increasing delocalization away from the Fe(II) center lengthens the charge-separated lifetime, which is an important first step in achieving long-lived charge transfer states for this class of compounds
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Title: ADDITIVE MANUFACTURING FOR RAPID PROTOTYPING OF MM-WAVE CIRCUITS
Creator: Crump, Cameron Austin
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Additive manufacturing (AM) has recently attracted significant interest to meet the need of nextgeneration of wireless systems, and the growing demand for customization and rapid prototyping of electronic systems. In addition, AM is being investigated to supplement and in some cases replace traditional microelectronic fabrication techniques. This is to lessen the ecological impact of electronics manufacturing as well as to reduce cleanroom facility costs. This research work focuses on the use...
Show moreAdditive manufacturing (AM) has recently attracted significant interest to meet the need of nextgeneration of wireless systems, and the growing demand for customization and rapid prototyping of electronic systems. In addition, AM is being investigated to supplement and in some cases replace traditional microelectronic fabrication techniques. This is to lessen the ecological impact of electronics manufacturing as well as to reduce cleanroom facility costs. This research work focuses on the use of AM for the design and fabrication of microwave and millimeter wave components and systems, leading to heterogeneous integration. For systems integration, two major challenges to tackle are: (1) rapid printing of conductive regions with high precision and high conductivity; (2) selective deposition of dielectrics with varying geometries surrounding active and passive components. In this work, printing of both conductors and dielectrics was carried out using aerosol jet printing (AJP). AJP allows for high resolution printing (~10 μm) at a large standoff distance (~10 mm). Silver (Ag) based inks were investigated to achieve high conductivity and polymers (benzocyclobutene, BCB and Polyimide, PI) as low-loss dielectric materials.
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Title: AGGREGATE PLANNING IN MANUFACTURING OF REUSABLE CONTAINERS
Creator: Tao, Jinli
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Aggregate production planning (APP) is a method to make several decisions simultaneously on production, inventory, and workforce levels over a finite time horizon, aiming to maximize the profit or minimize the cost while meeting fluctuating demands. Building mathematical models that reflect real-world problems is often difficult, as the constraints are usually intricate and may interact with each other. Decomposing the interconnected system into a number of independent phases could simplify...
Show moreAggregate production planning (APP) is a method to make several decisions simultaneously on production, inventory, and workforce levels over a finite time horizon, aiming to maximize the profit or minimize the cost while meeting fluctuating demands. Building mathematical models that reflect real-world problems is often difficult, as the constraints are usually intricate and may interact with each other. Decomposing the interconnected system into a number of independent phases could simplify the problem; however, it may not guarantee the optimality of the best solutions due to the missed constraints between stages. In this study, two mixed integer programming models for the manufacturing of reusable plastic containers are presented. One is based on the flow of the material and the other is based on the level of the workforce at each period. The proposed models are able to (i) deal with varying demand, (ii) reflect various regulations and restrictions of public and private warehouses for storing materials, and (iii) identify the importance of subcontracting when demand increases dramatically. Both mathematical models are implemented in the case of packaging manufacturing. A comprehensive sensitivity analysis has been conducted on different parameters of the problem to test the effect of parameter changes. To sum up, the general framework of the mathematical models not only can be used for reusable container manufacturing but also the manufacturing of any type of product with a similar supply chain network.
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Title: AI ACCELERATED COLLISIONAL CROSS SECTION PREDICTION FOR HIGH THROUGHPUT METABOLITE IDENTIFICATION
Creator: Tanemura, Kiyoto Aramis
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Metabolomics refers to the collective characterization of small organic molecules in a biological sample. While instrumentation and software continues to improve for metabolomics studies, the fraction of annotated signals in untargeted metabolomics experiments remain small. Translating features to metabolite identities present a major bottleneck, confounded by the lack of authentic standards to build comprehensive experimental databases. I illustrate the development of collisional cross...
Show moreMetabolomics refers to the collective characterization of small organic molecules in a biological sample. While instrumentation and software continues to improve for metabolomics studies, the fraction of annotated signals in untargeted metabolomics experiments remain small. Translating features to metabolite identities present a major bottleneck, confounded by the lack of authentic standards to build comprehensive experimental databases. I illustrate the development of collisional cross section (CCS) prediction methods through deduction from theory and induction from available data. The theoretical CCS prediction involves multistep modeling of conformational ensemble followed by simulation of ion mobility. The advanced computational chemistry operations were automated using the AutoGraph conformational clustering protocol and implementation of the workflow in Snakemake. In a complementary approach, I applied a graph convolutional deep Bayesian neural net to predict CCS values and their uncertainty values. The quantified uncertainty was used to guide ab initio prediction of CCS values in an active learning strategy. The developed methodologies lay the foundation to a continuously refining in silico CCS library to aid in metabolite annotation.
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Title: AN EVOLUTIONARY MULTI-OBJECTIVE APPROACH TO SUSTAINABLE AGRICULTURAL WATER AND NUTRIENT OPTIMIZATION
Creator: Kropp, Ian Meyer
Date: 2018
Collection: Electronic Theses & Dissertations
Description: One of the main problems that society is facing in the 21st century is that agricultural production must keep pace with a rapidly increasing global population in an environmentally sustainable manner. One of the solutions to this global problem is a system approach through the application of optimization techniques to manage farm operations. However, unlike existing agricultural optimization research, this work seeks to optimize multiple agricultural objectives at once via multi-objective...
Show moreOne of the main problems that society is facing in the 21st century is that agricultural production must keep pace with a rapidly increasing global population in an environmentally sustainable manner. One of the solutions to this global problem is a system approach through the application of optimization techniques to manage farm operations. However, unlike existing agricultural optimization research, this work seeks to optimize multiple agricultural objectives at once via multi-objective optimization techniques. Specifically, the algorithm Unified Non-dominated Sorting Genetic Algorithm-III (U-NSGA-III) searched for irrigation and nutrient management practices that minimized combinations of environmental objectives (e.g., total irrigation applied, total nitrogen leached) while maximizing crop yield for maize. During optimization, the crop model named the Decision Support System for Agrotechnology Transfer (DSSAT) calculated the yield and nitrogen leaching for each given management practices. This study also developed a novel bi-level optimization framework to improve the performance of the optimization algorithm, employing U-NSGA-III on the upper level and Monte Carlo optimization on the lower level. The multi-objective optimization framework resulted in groups of equally optimal solutions that each offered a unique trade-off among the objectives. As a result, producers can choose the one that best addresses their needs among these groups of solutions, known as Pareto fronts. In addition, the bi-level optimization framework further improved the number, performance, and diversity of solutions within the Pareto fronts.
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Title: AN EXPLORATORY TEST OF FAR-RIGHT EXTREMISTS PROTECTIVE AND PUTATIVE (RISK) FACTORS; IN BOTH VIOLENT AND NON-VIOLENT OFFENDERS USING THE EXTREMIST CRIME DATABASE
Creator: Lindsay, Lance Jhordan Asquith
Date: 2021
Collection: Electronic Theses & Dissertations
Description: ABSTRACTAN EXPLORATORY TEST OF FAR-RIGHT EXTREMISTS PROTECTIVE AND PUTATIVE (RISK) FACTORS; IN BOTH VIOLENT AND NON-VIOLENT OFFENDERS USING THE EXTREMIST CRIME DATABASEByLance Jhordan Asquith. LindsayResearch in the field of extremism studies have steadily progressed as it emerged from the main field of terrorism studies. This progression has gone from defining terrorism and its root causes; to measuring cognitive and behavioral indicators which may predict the likelihood of radicalization...
Show moreABSTRACTAN EXPLORATORY TEST OF FAR-RIGHT EXTREMISTS PROTECTIVE AND PUTATIVE (RISK) FACTORS; IN BOTH VIOLENT AND NON-VIOLENT OFFENDERS USING THE EXTREMIST CRIME DATABASEByLance Jhordan Asquith. LindsayResearch in the field of extremism studies have steadily progressed as it emerged from the main field of terrorism studies. This progression has gone from defining terrorism and its root causes; to measuring cognitive and behavioral indicators which may predict the likelihood of radicalization toward extremism. This comes after tedious debates about typology and causes of terrorism in the field, there are still challenges to overcome as most research relies on open-source data. Through efforts to make this field more established the Extremist Crime Database (ECDB) stands out as a standard for this pursuit having some of the best open-source data and widespread usage. The database captures extremist violence from 1990 to 2014 and is a relational database that links event level data to individual offender level data. This database created by Freilich and colleagues (2014) has resulted in the ability to conduct quantitative analysis beyond descriptive statistics. The main question: are there differences in these risk and protective factors that lead to non-violent or violent outcomes of offenders in this sample? These nuances in the frequency of factors may explain why an individual followed the offending trajectory and if these differences explain offending.
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Title: AN INVESTIGATION OF MOTIVATIONAL STRATEGY USE BY FL SWAHILI AND ZULU INSTRUCTORS IN THE UNITED STATES
Creator: AKIDING, MAGDALYNE OGUTI
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Second language (L2) teachers’ practices in the classroom can influence their students’ motivation for learning the L2. However, most of the research in this area has been conducted with students learning English as L2. Guilloteaux and Dörnyei (2008) recommended that more research be conducted on the use of motivational teaching practices in different languages, cultures, and instructional contexts to enrich the literature on this topic. In line with that recommendation, I had three goals...
Show moreSecond language (L2) teachers’ practices in the classroom can influence their students’ motivation for learning the L2. However, most of the research in this area has been conducted with students learning English as L2. Guilloteaux and Dörnyei (2008) recommended that more research be conducted on the use of motivational teaching practices in different languages, cultures, and instructional contexts to enrich the literature on this topic. In line with that recommendation, I had three goals with the current study: first, to investigate which motivational teaching practices are used by four teachers of two African languages in the United States; secondly, to investigate learners’ perceptions of the impacts of those motivational teaching practices on their motivated behaviour; and thirdly, to find out the impact of select factors on teachers’ implementation of those teaching practices. I employed a case study methodology (Duff, 2014) and collected classroom-based data from the four teachers of Swahili and Zulu and their students. Data were collected by means of classroom observations, stimulated recall sessions, and semi-structured interviews. The descriptive qualitative data allowed for the teaching and learning contexts of the participants to be captured in an in-depth manner. Findings revealed that the implementation of motivational teaching practices by the four teachers varied, with some using more motivational strategies than others. While learners’ perceptions about those strategies were mostly positive, results also revealed instances where students did not perceive some practices as motivational despite their teachers thinking that they were. Factors such as the teachers’ cultural backgrounds and training were found to influence the teachers’ motivational strategy use. Additionally, teachers’ preparedness to teach remotely, the challenges of remote teaching, and institutional support were found to affect their implementation of motivational teaching practices. I discuss these results in particular in light of the time of data collection, which was during the COVID-19 pandemic. Overall, the findings revealed that the four teachers implemented motivational teaching practices from all four stages of Dörnyei’s (2001) process-oriented model of L2 motivation, and that the teachers with more communicative orientations to teaching tended to use materials and teaching strategies in the classroom that also further promoted motivation within their students. These findings contribute to the literature on motivational teaching practices and highlight how teachers of African languages may have unique challenges in implementing motivational teaching practices, but that they as a collective work hard to foster motivation in ways that they believe will be most impactful to learners, especially in the virtual teaching environment of the times.
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Title: ANALYSIS OF ERWINIA AMYLOVORA POPULATION DYNAMICS AT FLOWER BLOOM AND FURTHER SYSTEMIC MOVEMENT OF THE PATHOGEN THROUGH HOST TISSUE
Creator: Slack, Suzanne M.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Population dynamics of Erwinia amylovora have been utilized for many applications over the past 50 years. In this work, populations were tracked over the course of apple bloom under naturally occurring environmental conditions. Flower stigmas inoculated on the 1st day of being open can harbor large (107) populations after 3 or 5 days post inoculation, with 100-fold increases in E. amylovora stigma populations observed in atmospheric conditions with daily average temperatures near 14oC. These...
Show morePopulation dynamics of Erwinia amylovora have been utilized for many applications over the past 50 years. In this work, populations were tracked over the course of apple bloom under naturally occurring environmental conditions. Flower stigmas inoculated on the 1st day of being open can harbor large (107) populations after 3 or 5 days post inoculation, with 100-fold increases in E. amylovora stigma populations observed in atmospheric conditions with daily average temperatures near 14oC. These large 100-fold increases seem to occur at night, indicating that Erwinia amylovora is able to infect flowers in colder field temperatures than previously reported. In tandem, timing of antibiotic application relative to E. amylovora presence on flower stigmas had little impact on population dynamics, with streptomycin and kasugamycin consistently reducing populations while oxytetracycline was more variable. This study also led to the identification that Kasumin is prone to photodegradation. Culturable bacteria, yeast, and fungal populations were assessed over the course of bloom in relation to application of a biological control agent yeast (Aureobasidium pullulans) and a contact sterilant. Though populations fell rapidly directly after application, by 24 hours all populations returned to pre-spray levels. In regards to further systemic spread, a type three secretion system effector was indicted in blocking the abscission of infected flowers. The use of prohexadione calcium (Pro-ca) and acibenzolar-S-methyl (ASM) reduced internal E. amylovora spread in a seemingly synergistic manner on young trees, with rates of 28.3 g Pro-Ca + 28.3 g ASM or 56.6 g Pro-Ca + 28.3 g ASM. The sum of this work gives us a better understanding of E. amylovora population dynamics in field conditions as well as the population response to current treatment options.
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Title: ARID1A MUTANT PATHOGENESIS OF THE ENDOMETRIAL EPITHELIUM
Creator: Reske, Jake Jordan
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Women’s health diseases represent an understudied, widespread medical concern with historically limited treatment options. Diseases of the endometrium, the innermost lining of the uterus, are a highly prevalent public burden. Endometriosis occurs in 1 in 10 women, and endometrial cancer is the most common gynecologic malignancy in the United States. Recent advances have revealed recurrent genetic causes of endometrial diseases, including gene mutations known to play a role in cancer...
Show moreWomen’s health diseases represent an understudied, widespread medical concern with historically limited treatment options. Diseases of the endometrium, the innermost lining of the uterus, are a highly prevalent public burden. Endometriosis occurs in 1 in 10 women, and endometrial cancer is the most common gynecologic malignancy in the United States. Recent advances have revealed recurrent genetic causes of endometrial diseases, including gene mutations known to play a role in cancer development. ARID1A is one such gene that is commonly mutated in endometrial diseases, and it encodes a protein involved in regulating DNA packaging and activity in the cell nucleus within a large complex known as SWI/SNF. The focus of this dissertation is to improve our understanding of how ARID1A mutations promote endometrial diseases at multiple biological levels, with a particular focus on how disrupted chromatin regulation affects physiologically relevant gene expression. In these works, genetic engineering techniques are leveraged in mice and human cell-based models supported by public and clinical data to establish the consequences of ARID1A mutations in the endometrium and how they relate to other common genetic alterations in these diseases. These studies have revealed that ARID1A is a tumor suppressor in the endometrial epithelium, such that ARID1A loss drives cellular invasion into nearby tissue. ARID1A mutations also promote invasive metastasis and squamous metaplasia in the context of aggressive TP53 mutations. At the level of chromatin, ARID1A and SWI/SNF directly regulate endometrial epithelial identity genes through both promoter and distal enhancer chromatin interactions. Mechanistically, ARID1A mutant invasion is driven by cell identity control regions known as super-enhancers that become hyperactivated, which can be reversed pharmacologically. Moreover, ARID1A physically and genomically interacts with other nuclear chromatin regulators to govern gene activation states through variant histone regulation. These works have contributed in multiple aspects toward deciphering how ARID1A mutations promote disease in the endometrium, including pre-clinical support for using epigenetic therapies to treat invasive ARID1A mutant endometrial conditions. Future efforts will aim to further identify and understand molecular and biochemical mechanisms linking ARID1A and SWI/SNF chromatin remodeling activity to regulation of gene expression. Ongoing work seeks to explain roles of ARID1A and SWI/SNF epigenetic regulation in normal physiological processes of the endometrium, such as hormone signaling across the menstrual cycle.
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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: ASSESSING REPRODUCTIVE SUCCESS OF LAKE STURGEON (ACIPENSER FULVESCENS) ASSOCIATED WITH NATURAL AND CONSTRUCTED SPAWNING REEFS IN A LARGE RIVER SYSTEM USING PEDIGREE ANALYSIS
Creator: Hunter III, Robert D.
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Habitat modification including barriers to migration, poor water quality, and modification of benthic habitat has contributed to the decline of lake sturgeon (Acipenser fulvescens) abundances in the Great Lakes. Lack of habitat was identified as a limiting factor for lake sturgeon recovery in the St. Clair-Detroit River System (SCDRS). To increase habitat availability in the SCDRS with the intent of increasing lake sturgeon populations, seven spawning reefs were constructed. Using 741 eggs...
Show moreHabitat modification including barriers to migration, poor water quality, and modification of benthic habitat has contributed to the decline of lake sturgeon (Acipenser fulvescens) abundances in the Great Lakes. Lack of habitat was identified as a limiting factor for lake sturgeon recovery in the St. Clair-Detroit River System (SCDRS). To increase habitat availability in the SCDRS with the intent of increasing lake sturgeon populations, seven spawning reefs were constructed. Using 741 eggs and larvae collected during traditional assessments, genetic pedigree analysis was used to further quantify spawning habitat use. In 2015 and 2016, 339-349 spawners were estimated to have contributed offspring across all sites. The effective number of breeders was estimated at 295-314 spawners, with mean (4.26-4.37 larvae) and variance (6.26-7.20) in individual reproductive success across all reefs and in 2015 and 2016. Evidence of adults spawning at multiple reefs within and between rivers was revealed by shared sib-ship of offspring collected at multiple locations. Comparison between gear types revealed that differences in the way individuals are collected can affect estimates generated from genetic pedigree analysis. Finally, species richness estimators were combined with genetic pedigree analysis to estimate the total number of spawners contributing offspring at constructed reefs (11-92 spawners per reef per year). Detailed information regarding lake sturgeon spawning behavior associated with spawning habitat construction in the SCDRS informs future assessment and management action for conservation of lake sturgeon throughout their range.
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Title: ASSESSING THE ECOLOGICAL AND ANTHROPOGENIC FACTORS AFFECTING GIRAFFE SURVIVAL IN EAST AFRICA
Creator: Muneza, Arthur Bienvenu
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Giraffe (Giraffa spp.) populations have declined by approximately 35% in the last 30 years, with extinctions documented in seven African countries. This decline has been attributed primarily to ecological and anthropogenic factors. In this dissertation, I assessed the impact that disease and human-interactions with wildlife have had on giraffe populations. In Chapter One, I quantified the severity of a skin disease that manifests as crusty, greyish-brown lesions, and has been recorded in at...
Show moreGiraffe (Giraffa spp.) populations have declined by approximately 35% in the last 30 years, with extinctions documented in seven African countries. This decline has been attributed primarily to ecological and anthropogenic factors. In this dissertation, I assessed the impact that disease and human-interactions with wildlife have had on giraffe populations. In Chapter One, I quantified the severity of a skin disease that manifests as crusty, greyish-brown lesions, and has been recorded in at least seven countries. I positioned my study in Tanzania, which has some of the highest rates of giraffe skin disease (GSD) recorded in Africa. Using photogrammetric analysis of camera trap images and digital photos of known individual giraffes, I classified GSD lesions into categories of none, mild, moderate, and severe. My study demonstrated that camera trap images presented an informative platform for skin disease ecology studies. In Chapter Two, I evaluated giraffe-lion interactions in Ruaha National Park, where more than 85% of the giraffe population has GSD. The aim of my study was to assess whether GSD may negatively influence the likelihood of giraffes surviving lion predation attempts. Occurrence of lion marks of was higher for adults and males in the giraffe population suggesting that these individuals were more likely to survive lion attacks. I also found that giraffes are an important prey species for lions in Ruaha National Park but GSD severity plays a minor role in influencing likelihood of surviving a lion predation attempt. I further explored the ecological implications of disease ecology on predator-prey interactions. In Chapter Three, I documented how giraffe body parts are acquired and their intended use (consumptive, trophy, or medicative), in Tsavo Conservation Area, southern Kenya. I conducted semi-structured surveys among 331 households to assess correlations between nine socioeconomic factors and use of giraffe parts. I found that giraffe parts mostly had consumptive and trophy uses. Giraffe parts were predominantly acquired through one-time suppliers, opportunistic access, and widely-known markets. Three variables, namely gender, occupation, and land ownership were significantly and positively correlated with use of giraffe parts. This study detailed the complex nature of poaching and trade of species of conservation concern in coupled human and natural systems. In Chapter Four, I explored the complex ways in which background conditions in the environment, coupled with previous experience with wildlife risks influences people’s attitudes toward wildlife in Tsavo Conservation Area, southern Kenya. Respondents stated that baboons (Papio cynocephalus), elephants (Loxodonta africana), and lions (Panthera leo) posed the greatest risks to human security and private property. Respondents that experienced previous risks from wildlife in their villages desired those populations to decrease whereas respondents without access to grazing lands for livestock were inclined to see those wildlife populations increase. My study showed that human attitudes toward wildlife in coupled human and natural systems are more complex than previously considered. I conclude my dissertation by providing considerations for future studies and highlighting the importance of tailoring conservation interventions to the critically important local contexts and traditional knowledge.
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Title: ASSURING THE ROBUSTNESS AND RESILIENCY OF LEARNING-ENABLED AUTONOMOUS SYSTEMS
Creator: Langford, Michael Austin
Date: 2022
Collection: Electronic Theses & Dissertations
Description: As Learning-Enabled Systems (LESs) have become more prevalent in safety-critical applications, addressing the assurance of LESs has become increasingly important. Because machine learning models in LESs are not explicitly programmed like traditional software, developers typically have less direct control over the inferences learned by LESs, relying instead on semantically valid and complete patterns to be extracted from the system’s exposure to the environment. As such, the behavior of an LES...
Show moreAs Learning-Enabled Systems (LESs) have become more prevalent in safety-critical applications, addressing the assurance of LESs has become increasingly important. Because machine learning models in LESs are not explicitly programmed like traditional software, developers typically have less direct control over the inferences learned by LESs, relying instead on semantically valid and complete patterns to be extracted from the system’s exposure to the environment. As such, the behavior of an LES is strongly dependent on the quality of its training experience. However, run-time environments are often noisy or not well-defined. Uncertainty in the behavior of an LES can arise when there is inadequate coverage of relevant training/test cases (e.g., corner cases). It is challenging to assure safety-critical LESs will perform as expected when exposed to run-time conditions that have never been experienced during training or validation. This doctoral research contributes automated methods to improve the robustness and resilience of an LES. For this work, a robust LES is less sensitive to noise in the environment, and a resilient LES is able to self-adapt to adverse run-time contexts in order to mitigate system failure. The proposed methods harness diversity-driven evolution-based methods, machine learning, and software assurance cases to train robust LESs, uncover robust system configurations, and foster resiliency through self-adaptation and predictive behavior modeling. This doctoral work demonstrates these capabilities by applying the proposed framework to deep learning and autonomous cyber-physical systems.
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Title: Abstract homomorphisms of algebraic groups : rigidity and group actions
Creator: Ruiter, Joshua
Date: 2022
Collection: Electronic Theses & Dissertations
Description: We investigate two related problems involving abstract homomorphisms between the groups of rational points of algebraic groups. First, we show that under appropriate assumptions, abstract representations of quasi-split special unitary groups associated with quadratic extensions of the field of definition have standard descriptions, i.e. can be factored as a group homomorphism induced by a morphism of algebras, followed by a homomorphism arising from a morphism of algebraic groups. This...
Show moreWe investigate two related problems involving abstract homomorphisms between the groups of rational points of algebraic groups. First, we show that under appropriate assumptions, abstract representations of quasi-split special unitary groups associated with quadratic extensions of the field of definition have standard descriptions, i.e. can be factored as a group homomorphism induced by a morphism of algebras, followed by a homomorphism arising from a morphism of algebraic groups. This establishes a new case of a longstanding conjecture of Borel and Tits. In the second part, we apply existing results on standard descriptions for abstract representations of Chevalley groups to study some rigidity properties of actions of elementary subgroups on algebraic varieties.The thesis is organized as follows. To provide context for the study of abstract homomorphisms, in section 1 we give a historical overview of key developments going back to Cartan's work on homomorphisms of Lie groups. In section 2, we prove our rigidity result for special unitary groups, using a strategy inspired by work of Igor Rapinchuk which depends crucially on the construction of certain algebraic rings associated to abstract representations. In section 3, we apply existing rigidity statements for representations of elementary subgroups of Chevalley groups to study rigidity properties of these groups acting on affine algebraic varieties and projective surfaces. We discuss some open questions and plans for future work in section 4. In the appendices, we collect some relevant background material on algebraic rings, and also provide details on the computations of commutator relations needed for the constructions in section 2.
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Title: Accusing Muslims of terrorism : Islam, secularism, and religious violence in the United States
Creator: Sadequee, Sharmin
Date: 2017
Collection: Electronic Theses & Dissertations
Description: This dissertation describes the ways in which the securitized secular laws of the state act to regulate and control Muslims and the practices of Islam through "terrorism" prosecutions in the United States. In order to eliminate terrorism violence, the security state has created an exception to regular legal norms by establishing a court within a court and a prison within a prison, where normal legal procedures are not followed for those Muslim immigrants and American Muslim citizens accused...
Show moreThis dissertation describes the ways in which the securitized secular laws of the state act to regulate and control Muslims and the practices of Islam through "terrorism" prosecutions in the United States. In order to eliminate terrorism violence, the security state has created an exception to regular legal norms by establishing a court within a court and a prison within a prison, where normal legal procedures are not followed for those Muslim immigrants and American Muslim citizens accused of "terrorism" related offenses. I address the ways in which Muslims have been conditioned and affected by the securitized secular laws that are applied in "terrorism" cases, and I also discuss how human-rights advocacy around the accused challenge and resist these discriminatory practices. Based on 24 months of ethnographic fieldwork; observations of federal terrorism trials; a review of prison writings; and interviews with families of the accused, activists, lawyers, and human-rights advocates, I address the legal practices of securitized laws concerned with preventing "terrorism," their impact both inside and outside of judicial institutions, and the power of these practices on the lived experiences of Muslim Americans. While some authorities claim that preventive "terrorism" prosecutions are necessary to eradicate violence, I suggest that the main concerns of the security state are really about eradicating religious thought and practices that contradict the secular definition of acceptable religion. -- Abstract.
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Title: Achieving reliable distributed systems : through efficient run-time monitoring and predicate detection
Creator: Tekken Valapil, Vidhya
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Runtime monitoring of distributed systems to perform predicate detection is critical as well as a challenging task. It is critical because it ensures the reliability of the system by detecting all possible violations of system requirements. It is challenging because to guarantee lack of violations one has to analyze every possible ordering of system events and this is an expensive task. In this report, wefocus on ordering events in a system run using HLC (Hybrid Logical Clocks) timestamps,...
Show moreRuntime monitoring of distributed systems to perform predicate detection is critical as well as a challenging task. It is critical because it ensures the reliability of the system by detecting all possible violations of system requirements. It is challenging because to guarantee lack of violations one has to analyze every possible ordering of system events and this is an expensive task. In this report, wefocus on ordering events in a system run using HLC (Hybrid Logical Clocks) timestamps, which are O(1) sized timestamps, and present some efficient algorithms to perform predicate detection using HLC. Since, with HLC, the runtime monitor cannot find all possible orderings of systems events, we present a new type of clock called Biased Hybrid Logical Clocks (BHLC), that are capable of finding more possible orderings than HLC. Thus we show that BHLC based predicate detection can find more violations than HLC based predicate detection. Since predicate detection based on both HLC and BHLC do not guarantee detection of all possible violations in a system run, we present an SMT (Satisfiability Modulo Theories) solver based predicate detection approach, that guarantees the detection of all possible violations in a system run. While a runtime monitor that performs predicate detection using SMT solvers is accurate, the time taken by the solver to detect the presence or absence of a violation can be high. To reduce the time taken by the runtime monitor, we propose the use of an efficient two-layered monitoring approach, where the first layer of the monitor is efficient but less accurate and the second layer is accurate but less efficient. Together they reduce the overall time taken to perform predicate detection drastically and also guarantee detection of all possible violations.
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Title: Action-Oriented Studies in Green Criminology and a Harmful Trade in Pet Wildlife in Trinidad and Tobago
Creator: Gibson, Mark Charles
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation presents five chapters, inclusive of three manuscripts styled as draft publications, to advance the contested paradigm of green criminology—or the study of crimes and harms that involve the natural world, non-human species, and the human communities that depend on them—and to support the emerging professional practice of non-governmental wildlife trade reduction. Two of the presented manuscripts meet the requirements for submission to scientific journals in criminology,...
Show moreThis dissertation presents five chapters, inclusive of three manuscripts styled as draft publications, to advance the contested paradigm of green criminology—or the study of crimes and harms that involve the natural world, non-human species, and the human communities that depend on them—and to support the emerging professional practice of non-governmental wildlife trade reduction. Two of the presented manuscripts meet the requirements for submission to scientific journals in criminology, while another is a long-form text modeled on contemporary non-governmental ‘wildlife trade assessment’ reports. The specific wildlife trade under study is a harmful trade in pet wildlife occurring in Trinidad and Tobago and the wider world. This trade was particularly under-studied prior to this dissertation research project and broader initiative. The dissertation is action-oriented in that it seeks to support the green criminology paradigm's empirical, theoretical, and technical development. The resulting manuscript-style chapters have been designed using a best-practice ‘Open Standards’ planning approach now popular in wildlife trade reduction projects. The underlying research activities were also action-oriented in that they were and continue to be conducted in partnership with local activists and scientists as part of a non-governmental project to reduce the harmful trade in pet wildlife trade in Trinidad and Tobago (see www.nurturenaturett.org). The underlying research included focus group discussions with wild animal keepers (n=75), key informant interviews (n=172) with seven stakeholder groups, more than two years of participant observation of physical sites and social media, a national household survey on animal keeping (n=2004), and a taxonomic legal inventory of wildlife laws in Trinidad and Tobago and its trade partners. The first chapter, “Introduction,” provides essential background information on the dissertation research, encompassing project, and implementing researcher. In this way, the chapter describes the developmental context of this dissertation thesis and the strategies employed to produce the dissertation chapters. The second chapter, “The illegal keeping of pet wildlife in Trinidad and Tobago: Diversity, prevalence, populations, and harms,” is designed for submission to a criminological journal on global crime issues and provides insights into the nature of an illegal wildlife trade in a Caribbean country. The third chapter, “‘We all know it’s inhumane’: The awareness and justification of green crimes and harms among Trinidadian songbird keepers,” is designed for submission to a criminological journal on social deviance and provides insights for the development of Neutralization Theory to reduce green crimes and harms. The fourth chapter, “An assessment of the harmful trade in songbirds in Trinidad and Tobago and the wider world,” is designed as a gray-literature ‘wildlife trade assessment’ to educate and empower activists, donors, and policymakers in Trinidad and Tobago and the wider world. A final chapter, “Conclusion and Reflections,” considers the researcher’s experience in relation to action, green criminology, project-based intervention, and science-based activism. The researcher’s concluding reflections include the identification of several next steps to advance green criminology for the continuing and future reduction of harmful wildlife trades and other green crimes and harms.
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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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Title: Adaptive and Automated Deep Recommender Systems
Creator: Zhao, Xiangyu
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Recommender systems are intelligent information retrieval applications, and have been leveraged in numerous domains such as e-commerce, movies, music, books, and point-of-interests. They play a crucial role in the users' information-seeking process, and overcome the information overload issue by recommending personalized items (products, services, or information) that best match users' needs and preferences. Driven by the recent advances in machine learning theories and the prevalence of deep...
Show moreRecommender systems are intelligent information retrieval applications, and have been leveraged in numerous domains such as e-commerce, movies, music, books, and point-of-interests. They play a crucial role in the users' information-seeking process, and overcome the information overload issue by recommending personalized items (products, services, or information) that best match users' needs and preferences. Driven by the recent advances in machine learning theories and the prevalence of deep learning techniques, there have been tremendous interests in developing deep learning based recommender systems. They have unprecedentedly advanced effectiveness of mining the non-linear user-item relationships and learning the feature representations from massive datasets, which produce great vitality and improvements in recommendations from both academic and industry communities.Despite above prominence of existing deep recommender systems, their adaptiveness and automation still remain under-explored. Thus, in this dissertation, we study the problem of adaptive and automated deep recommender systems. Specifically, we present our efforts devoted to building adaptive deep recommender systems to continuously update recommendation strategies according to the dynamic nature of user preference, which maximizes the cumulative reward from users in the practical streaming recommendation scenarios. In addition, we propose a group of automated and systematic approaches that design deep recommender system frameworks effectively and efficiently from a data-driven manner. More importantly, we apply our proposed models into a variety of real-world recommendation platforms and have achieved promising enhancements of social and economic benefits.
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Title: Adaptive behavior in sandbox games : how motivation shapes use of affordances in virtual worlds
Creator: Lee, Joomi
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Users of video games actively interact with the game environment, impacting the contents of the environment and altering their subsequent behaviors in meaningful ways. Although motivation is essential to guide behavior, not much work has investigated how motivational processes shape in-game behavior. Therefore, this study incorporates understandings of player motivation with a concept of affordances to build a model of adaptive player behavior in games and virtual environments. The primary...
Show moreUsers of video games actively interact with the game environment, impacting the contents of the environment and altering their subsequent behaviors in meaningful ways. Although motivation is essential to guide behavior, not much work has investigated how motivational processes shape in-game behavior. Therefore, this study incorporates understandings of player motivation with a concept of affordances to build a model of adaptive player behavior in games and virtual environments. The primary prediction was that threats and resources in games will shape initial motivated behaviors to explore and use affordances of the virtual world at variable rates. Using a custom-designed game with varying threats and resources available to players, the approach and avoidance behavior players exhibit in response to motivationally relevant in-game encounters was examined in a laboratory experiment. The moderating role of trait-level motivational reactivity in facilitating and inhibiting motivational responses to the game environment was also examined. A series of repeated measures ANOVAs demonstrated that players' adaptively respond to virtual environment affordances to gain benefits and avoid threats, evidenced by facilitated approach behaviors in the absence of threat as well as facilitated avoidance behaviors under threatening circumstances. Furthermore, individual differences in appetitive and defensive trait motivational reactivity moderated these effects in significant fashion. Overall, these findings clarify the role of game mechanics and affordances of the virtual environment as key shapers of user behavior, and demonstrate that gameplay is made up of discrete adaptive behaviors guided by motivated responses to the game environment.
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