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Title: Design and Analysis of Sculpted Rotor Interior Permanent Magnet Machines
Creator: Hayslett, Steven Lee
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Design of interior permanent magnet electrical machines is complex. Interior permanent magnet machines offer a good balance of cost, efficiency, and torque/power density. Maximum torque and power production of an interior permanent magnet machine is achieved through balancing design choices related to the permanent magnet and salient features. The embedded magnet within the salient structure of the rotor lamination results in an increase in harmonic content. In addition, interaction of the...
Show moreDesign of interior permanent magnet electrical machines is complex. Interior permanent magnet machines offer a good balance of cost, efficiency, and torque/power density. Maximum torque and power production of an interior permanent magnet machine is achieved through balancing design choices related to the permanent magnet and salient features. The embedded magnet within the salient structure of the rotor lamination results in an increase in harmonic content. In addition, interaction of the armature, control angle, and rotor reluctance structure creates additional harmonic content. These harmonics result in increased torque ripple, radial forces, losses, and other unwanted phenomena. Further improvements in torque and power density, and techniques to minimize harmonics, are necessary. Typical interior permanent magnet machine design results at the maximum torque per amp condition are at neither the maximum magnet nor maximum salient torque, but at the best combination of the two. The use of rotor surface features to align the magnet and the reluctance axis allows for improvement of torque and power density. Reduction of flux and torque harmonics is also possible through careful design of rotor sculpt features that are included at or near the surface of the rotor. Finite element models provide high fidelity and accurate results to machine performance but do not give insight into the relationship between design parameters and performance. Winding factor models describe the machine with a set of Fourier series equations, providing access to the harmonic information of both parameters and performance. Direct knowledge of this information provides better insight, a clear understanding of interactions, and the ability to develop a more efficient design process. A new analytical winding function model of the single-V IPM machine is introduced, which considers the sculpted rotor and how this model can be used in the design approach of machines.Rotor feature trends are established and utilized to increase design intuition and reduce dependency upon the lengthy design of experiment optimization processes. The shape and placement of the rotor features, derived from the optimization process, show the improvement in torque average and torque ripple of the IPM machine.
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Title: “BLACK, SET, SPIKE : ” AN ANALYSIS OF THE RACIAL EXPERIENCES OF BLACK FEMALE VOLLEYBALL PLAYERS IN EUROPE
Creator: Fry, Jen
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Sports and geography each profoundly impact the lived and professional experiences of Black female athletes. These experiences also significantly shape their personal and professional identities, as both deal with the occupation of space and the way people move and interact in geographic spaces. Little attention has been paid by the academic and athletic communities to the lived experiences of professional athletes who play abroad. Currently, minimal research has been conducted on the...
Show moreSports and geography each profoundly impact the lived and professional experiences of Black female athletes. These experiences also significantly shape their personal and professional identities, as both deal with the occupation of space and the way people move and interact in geographic spaces. Little attention has been paid by the academic and athletic communities to the lived experiences of professional athletes who play abroad. Currently, minimal research has been conducted on the experiences of Black female volleyball players (BFVPs) who have played in Europe and how race, gender identity, space, and sports affected their lived experiences abroad based on their identities. This dissertation utilized qualitative methods to analyze the racial experiences of Black women who have played professional volleyball in Europe and whose experiences have not been documented within studies of geography—or, more specifically, within perspectives of Black feminist thought, Black geographies, and theory of racial space. The goal of this dissertation was twofold: (a) explore how intersecting racial and gendered identities, place, and space influenced the racism encountered by U.S. BFVPs in Europe; and (b) provide a source of information for future Black female college athletes who want to play professionally but do not know what they do not know. By developing a body of literature within sports geography on the overlooked and unresearched experiences of professional Black female athletes (BFAs), I contributed to the ever-increasing body of literature on BFAs across various disciplines. Some of the discoveries from my research were that BFVPs experienced racism in ways similar to what they experienced within the United States, such as being oversexualized, expected to play up racially stereotypical views of Black women, and having their hair touched without their consent. They also experienced racism in wildly different ways, such as being spit on, teammates withholding English skills, and accusations of prostitution. When conducting my research, a qualitative approach of a brief demographic survey of 15 questions was sent to over 100 current and former BFVPs; I used these data to narrow down participants. There was a response rate of more than 50%, which resulted in 60 women filling out the survey; of that population, 51 checked yes to interest in being interviewed, and nine checked no to denote no interest in being interviewed. Based on criteria of the number of years played, countries played in, and teams played for, I narrowed the sample to 18 participants willing to participate in qualitative interviews. The theoretical frameworks of Black feminist thought, Black geographies, and theory of racial space were used to understand the experiences of the participants and helped me create a new conceptual framework called critical Black feminist sports geographies.
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Title: GOOD AT THIS BUT NOT AT THAT : MULTIDIMENSIONAL SELF-EVALUATIONS AND DIMENSIONAL COMPARISONS AT WORK
Creator: Mitchell, Rebecca
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Social comparison theory (Festinger, 1954) underlies findings and theory in many organizational behavior literatures, such as identity, justice, and compensation. Yet, the field has neglected to incorporate comparison theories introduced in other psychology literatures. Dimensional comparison theory (DCT; (Möller & Marsh, 2013) argues that, in addition to external comparisons to referent other, individuals also make internal comparisons across different dimensions of the self, defined within...
Show moreSocial comparison theory (Festinger, 1954) underlies findings and theory in many organizational behavior literatures, such as identity, justice, and compensation. Yet, the field has neglected to incorporate comparison theories introduced in other psychology literatures. Dimensional comparison theory (DCT; (Möller & Marsh, 2013) argues that, in addition to external comparisons to referent other, individuals also make internal comparisons across different dimensions of the self, defined within a multidimensional self-evaluation. This dissertation argues that DCT is related to, but distinct from, existing concepts within organizational behavior and is thus critical to integrate into our understanding of work. In three studies, a vignette study, one experiment, and one field study, I propose examining the effect that dimensional comparisons along these abilities have on individuals’ psychological investment as well as the resulting achievement and satisfaction in these dimensions. Further, I build upon existing DCT research in educational psychology through explicitly hypothesizing the interactive effect of dimensional and social comparisons, considering the role that the importance of the dimension to the group and the individual plays in these relationships, and examining dimensional comparisons using polynomial regression techniques.
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Title: TENSOR LEARNING WITH STRUCTURE, GEOMETRY AND MULTI-MODALITY
Creator: Sofuoglu, Seyyid Emre
Date: 2022
Collection: Electronic Theses & Dissertations
Description: With the advances in sensing and data acquisition technology, it is now possible to collect datafrom different modalities and sources simultaneously. Most of these data are multi-dimensional in nature and can be represented by multiway arrays known as tensors. For instance, a color image is a third-order tensor defined by two indices for spatial variables and one index for color mode. Some other examples include color video, medical imaging such as EEG and fMRI, spatiotemporal data...
Show moreWith the advances in sensing and data acquisition technology, it is now possible to collect datafrom different modalities and sources simultaneously. Most of these data are multi-dimensional in nature and can be represented by multiway arrays known as tensors. For instance, a color image is a third-order tensor defined by two indices for spatial variables and one index for color mode. Some other examples include color video, medical imaging such as EEG and fMRI, spatiotemporal data encountered in urban traffic monitoring, etc.In the past two decades, tensors have become ubiquitous in signal processing, statistics andcomputer science. Traditional unsupervised and supervised learning methods developed for one- dimensional signals do not translate well to higher order data structures as they get computationally prohibitive with increasing dimensionalities. Vectorizing high dimensional inputs creates problems in nearly all machine learning tasks due to exponentially increasing dimensionality, distortion of data structure and the difficulty of obtaining sufficiently large training sample size.In this thesis, we develop tensor-based approaches to various machine learning tasks. Existingtensor based unsupervised and supervised learning algorithms extend many well-known algorithms, e.g. 2-D component analysis, support vector machines and linear discriminant analysis, with better performance and lower computational and memory costs. Most of these methods rely on Tucker decomposition which has exponential storage complexity requirements; CANDECOMP-PARAFAC (CP) based methods which might not have a solution; or Tensor Train (TT) based solutions which suffer from exponentially increasing ranks. Many tensor based methods have quadratic (w.r.t the size of data), or higher computational complexity, and similarly, high memory complexity. Moreover, existing tensor based methods are not always designed with the particular structure of the data in mind. Many of the existing methods use purely algebraic measures as their objective which might not capture the local relations within data. Thus, there is a necessity to develop new models with better computational and memory efficiency, with the particular structure of the data and problem in mind. Finally, as tensors represent the data with more faithfulness to the original structure compared to the vectorization, they also allow coupling of heterogeneous data sources where the underlying physical relationship is known. Still, most of the current work on coupled tensor decompositions does not explore supervised problems.In order to address the issues around computational and storage complexity of tensor basedmachine learning, in Chapter 2, we propose a new tensor train decomposition structure, which is a hybrid between Tucker and Tensor Train decompositions. The proposed structure is used to imple- ment Tensor Train based supervised and unsupervised learning frameworks: linear discriminant analysis (LDA) and graph regularized subspace learning. The algorithm is designed to solve ex- tremal eigenvalue-eigenvector pair computation problems, which can be generalized to many other methods. The supervised framework, Tensor Train Discriminant Analysis (TTDA), is evaluated in a classification task with varying storage complexities with respect to classification accuracy and training time on four different datasets. The unsupervised approach, Graph Regularized TT, is evaluated on a clustering task with respect to clustering quality and training time on various storage complexities. Both frameworks are compared to discriminant analysis algorithms with similar objectives based on Tucker and TT decompositions.In Chapter 3, we present an unsupervised anomaly detection algorithm for spatiotemporaltensor data. The algorithm models the anomaly detection problem as a low-rank plus sparse tensor decomposition problem, where the normal activity is assumed to be low-rank and the anomalies are assumed to be sparse and temporally continuous. We present an extension of this algorithm, where we utilize a graph regularization term in our objective function to preserve the underlying geometry of the original data. Finally, we propose a computationally efficient implementation of this framework by approximating the nuclear norm using graph total variation minimization. The proposed approach is evaluated for both simulated data with varying levels of anomaly strength, length and number of missing entries in the observed tensor as well as urban traffic data. In Chapter 4, we propose a geometric tensor learning framework using product graph structures for tensor completion problem. Instead of purely algebraic measures such as rank, we use graph smoothness constraints that utilize geometric or topological relations within data. We prove the equivalence of a Cartesian graph structure to TT-based graph structure under some conditions. We show empirically, that introducing such relaxations due to the conditions do not deteriorate the recovery performance. We also outline a fully geometric learning method on product graphs for data completion.In Chapter 5, we introduce a supervised learning method for heterogeneous data sources suchas simultaneous EEG and fMRI. The proposed two-stage method first extracts features taking the coupling across modalities into account and then introduces kernelized support tensor machines for classification. We illustrate the advantages of the proposed method on simulated and real classification tasks with small number of training data with high dimensionality.
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Title: Greatest common divisors near S-units, applications, and conjectures on arithmetic abelian surfaces
Creator: Xiao, Zheng
Date: 2022
Collection: Electronic Theses & Dissertations
Description: We bound the greatest common divisor of two coprime multivariable polynomials evaluated at algebraic numbers, generalizing the work of Levin by thickening the finitely generated group to allow non-finitely generated elements. Going towards conjectured inequalities of Silverman and Vojta, an immediate corollary shows a similar inequality without a normal crossing assumption. The proofs rely on Schmidt's Subspace Theorem.As an application, we prove results on the greatest common divisors of...
Show moreWe bound the greatest common divisor of two coprime multivariable polynomials evaluated at algebraic numbers, generalizing the work of Levin by thickening the finitely generated group to allow non-finitely generated elements. Going towards conjectured inequalities of Silverman and Vojta, an immediate corollary shows a similar inequality without a normal crossing assumption. The proofs rely on Schmidt's Subspace Theorem.As an application, we prove results on the greatest common divisors of terms from two general linear recurrence sequences, extending the results of Levin, who considered the case where the linear recurrences are simple. The exceptional set is not as good as finitely many linear relations as in the simple case, but within the control of a logarithmic region, improving recent results of Grieve and Wang. An example shows that the logarithmic region is necessary.On abelian surfaces which come from the jacobians of hyperelliptic curves, we establish the connection between the GCD conjecture and the conjecture on arithmetic discriminant. It predicts, under particular situations, stronger inequality than Vojta's theorem of the arithmetic discriminant. We give some examples of extreme values of the arithmetic discriminant.
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Title: ESSAYS ON FIRMS, CLIMATE CHANGE AND FOOD SYSTEMS TRANSFORMATION
Creator: Nuhu, Ahmed Salim
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation broadly examines how climate change, and the rapidly transforming agrifood value chains are impacting firms, workers, and farmers in developing countries. Chapter 1 examines the effect of ignoring adaptation when estimating the short-run impacts of temperature shocks on workers and firms in developing regions. To do this, we first obtain naïve estimates of the short-run impacts of extreme temperatures (shocks) on workers’ wages and firm output in Sub-Saharan Africa using the...
Show moreThis dissertation broadly examines how climate change, and the rapidly transforming agrifood value chains are impacting firms, workers, and farmers in developing countries. Chapter 1 examines the effect of ignoring adaptation when estimating the short-run impacts of temperature shocks on workers and firms in developing regions. To do this, we first obtain naïve estimates of the short-run impacts of extreme temperatures (shocks) on workers’ wages and firm output in Sub-Saharan Africa using the standard panel fixed effects approach. We then obtain the pure short-run effects by adjusting the naïve estimates by conditioning the effects of the temperature shocks on the historical local temperature information held by firms and workers prior to the occurrence of the temperature shocks. The difference between the naïve and the pure short-run estimates provide evidence of adaptation. We find evidence of temperature shock effects on wages and output that similar to other studies from our naïve estimates. However, the estimated effects are much higher when we condition on firms’ prior knowledge of the local temperature. This finding indicates the importance of accounting for firms and workers’ knowledge of local temperature patterns (when estimating the impacts of temperature shocks) and provides evidence of incomplete adaptation (of up to 50% of the original effects). Evidence of incomplete adaptation suggests the presence of barriers to adaptation that need to be addressed to prevent a locking-in of vulnerability to climate change impacts. In a further application to the United States in Chapter 2, we find that accounting for the historical local temperature information is less relevant in the presence of more complete adaptation that may be aided by established institutional capacity for dealing with extreme weather. Taken together, these findings reveal (1) the importance of accounting for adaptation in estimating the impacts of short-term temperature shocks in developing regions with more barriers to adaptation and (2) that policies aimed at adaptation should not ignore local institutional and environmental contexts in which adaptation occurs. Chapter 3 examines the effects of the recent rise of numerous midstream agri-food firms and their authorized agents on smallholder soybean farmers in Zambia. Specifically, I examine the implications of non-contractual sale of soybean output to midstream firms and processors for the welfare of smallholder farmers. Using fixed effects and instrumental variables estimation techniques to address the endogeneity of the smallholder decision to sell to large-scale firms, I find significant positive crop income effects of selling to soybean large-scale firms on all smallholders. However, the observed effects only translate into higher total household incomes and poverty reduction for medium-scale smallholders (operating 5 ha- 20 ha) but not for small-scale smallholders operating less than five hectares. The positive crop income effects are mainly driven by the opportunity to sell more although small-scale smallholders also receive a price premium from selling to large buyers. These results suggest that the recent rise in purchasing activity by firms in the soybean industry in Zambia is benefiting smallholder farmers but not necessarily enough to move the smallest of these farmers out of poverty.
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Title: FACULTY BELIEFS OF CURRICULUM AND THE CONTEXTS IN WHICH THEY ENACT THOSE BELIEFS IN PRACTICE
Creator: Lopez , Kari Schueller
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Curriculum, and the teaching and learning that stem from it, is at the heart of each higher education institution. Faculty have the responsibility for developing curriculum in higher education contexts, yet little is known about the beliefs faculty hold of curriculum that underpin how they engage in the curriculum development process. Using qualitative methodology and Grundy’s (1987) theory of curriculum as product, curriculum as practice, and curriculum as praxis as a conceptual framework,...
Show moreCurriculum, and the teaching and learning that stem from it, is at the heart of each higher education institution. Faculty have the responsibility for developing curriculum in higher education contexts, yet little is known about the beliefs faculty hold of curriculum that underpin how they engage in the curriculum development process. Using qualitative methodology and Grundy’s (1987) theory of curriculum as product, curriculum as practice, and curriculum as praxis as a conceptual framework, this study explored the following research question with eleven faculty participants: What are faculty beliefs of curriculum and in what contexts do they act on those beliefs?Findings reveal faculty hold a myriad of deeply held beliefs about curriculum. They associate curriculum with their own courses, as well as with their academic programs or majors. Faculty beliefs center on the process of teaching and learning and the transformative possibility of the curriculum for students. They outlined both philosophical and practical goals for student learning, including preparing students for their lives as critical thinkers and engaged citizens, while also instilling applied skills to use in the workplace. Faculty enacted their beliefs when engaging in individual and/or group curriculum development work, and through pedagogy, teaching, and assessment. Faculty also discussed challenges to enacting curriculum and outlined administrative barriers, access to large-scale curriculum processes, tensions between teaching, research, and service responsibilities, and department culture. The discussion addresses these themes and includes recommendations for future research to examine the relationship between faculty beliefs of curriculum and accreditation bodies, the impact of department culture, faculty appointment type, and the COVID-19 pandemic on how faculty enact their beliefs of curriculum. Suggestions for practice include more training for faculty to engage in curriculum development work, more self-reflection opportunities, and recognition of curriculum-related work in the reappointment, promotion, and tenure process.
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Title: DEORPHANIZATION AND CHARACTERIZATION OF SEA LAMPREY OLFACTORY TRACE AMINE-ASSOCIATED RECEPTORS
Creator: JIA, LIANG
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The sense of smell plays an important role in mediating diverse behaviors in the animal kingdom. Odor detection in the sea lamprey is mediated by a limited number of odorant receptors (ORs) and trace amine-associated receptors (TAARs). Upon binding with odorants, the receptors are activated and subsequently activate the downstream neuronal signaling cascade that transforms the chemical information into electrophysiological signals. Odorous biogenic amines, when enriched in biological...
Show moreThe sense of smell plays an important role in mediating diverse behaviors in the animal kingdom. Odor detection in the sea lamprey is mediated by a limited number of odorant receptors (ORs) and trace amine-associated receptors (TAARs). Upon binding with odorants, the receptors are activated and subsequently activate the downstream neuronal signaling cascade that transforms the chemical information into electrophysiological signals. Odorous biogenic amines, when enriched in biological excretions, stimulate TAARs of the main olfactory epithelium and evoke innate behaviors in animals. I hypothesized that these biogenic amines are potent ligands for lamprey TAARs, and characterized the structural basis for amine recognition in these receptors. Chapter 1 describes discovery that spermine, an odorous polyamine in semen, serves as a sex pheromone in sea lamprey. Spermine potently stimulates the lamprey olfactory system, activates TAAR348 receptor, and attracts ovulated females. A novel antagonist to this receptor inhibits olfactory and female behavioral responses to spermine. This discovery elucidates a mechanism that male animals recruit mates through the release of chemical cues in ejaculates. In chapter 2, I demonstrated that two clades of independently evolved TAARs, represented by sea lamprey TAAR365 (sTAAR365) and mouse TAAR9 (mTAAR9), share a similar response profile. The results suggest a conserved mechanism whereby independently evolved TAAR receptors utilize convergent structural bases to detect various biogenic polyamines. In chapter 3, I found that a cadaverine-responsive sea lamprey TAAR receptor, TAAR346a, exhibits high basal activity when heterologously expressed in HEK293T cells. Triethylamine serves as an inverse agonist for TAAR346a that can specifically attenuate its high basal activity. These data support a model in which the inverse agonist recognizes only one of the two orthosteric sites used by the agonist as it elicits its inhibitory effect on the basal activity of the receptor. Further evidence was provided to highlight the importance of interhelical interactions in modulating ligand-independent activation of TAAR346a. Thus, this thesis contributes to a better understanding of sea lamprey olfaction and the structural basis of TAARs for amine recognition in vertebrate animals.
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Title: PARTNERSHIP AND PREDATION IN PLANT-BIOTIC INTERACTIONS : THEORY, METHODS, AND EVIDENCE
Creator: Rowe, Shawna L.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: As sessile organisms, plants face an endless series of encounters with other living organisms in their environment. Ranging from the beneficial to the harmful, the pressures of these biotic interactions force plants to rapidly adapt to survive and thrive. This dissertation is aimed at addressing questions about the metabolism of plant interactions with herbivores and nutritional symbionts in legumes. Despite spanning different systems and methods, these questions reflect my interest in...
Show moreAs sessile organisms, plants face an endless series of encounters with other living organisms in their environment. Ranging from the beneficial to the harmful, the pressures of these biotic interactions force plants to rapidly adapt to survive and thrive. This dissertation is aimed at addressing questions about the metabolism of plant interactions with herbivores and nutritional symbionts in legumes. Despite spanning different systems and methods, these questions reflect my interest in understanding the biochemistry underlying ecological and evolutionary function and my desire to develop tools that enable the investigation of such questions. To this end, the work in this dissertation is aimed at building conceptual and methodological tools to enable more thorough investigations of plant symbioses and, more broadly, plant-biotic interactions across levels of biological organization.First, I present a framework for making predictions on evolutionary trajectories and origins of plant--microbe communication systems. By highlighting the prevalence of coercive interactions in plant--microbe interactions, I demonstrate the plausibility of such interactions types to be an evolutionary precursor to seemingly stable signaling mechanisms. This work aims to provide useful evolutionary context for investigations concerning the evolutionary stability and exploitation of signaling mechanisms in established biological relationships. Second, I present collaborative work in which we developed and applied a cost-effective, high-throughput protocol for quantifying multiple biochemical defense responses from small quantities of plant tissue using spectrophotometric techniques. This protocol was then applied on two distinct populations of the legume Medicago polymorpha to investigate how changes defensive traits in responses to altered selective pressures have manifested over the course of novel range expansion. Our work demonstrated the feasibility and potential of assessing defense responses across plant populations. Further, the work documents a shift in herbivore preference of plants from familiar and unfamiliar ranges by demonstrating a herbivore preference for plant tissues with pre-induced defenses over uninduced tissues from an unfamiliar geographic range. Finally, I demonstrate the creation, construction, and validity of a novel microcosm system for assessing nutrient exchange in the symbiotic mutualism between plants and arbuscular mycorrhizal fungi (AMF). The novel system is reliable, biologically-relevant, durable, and sufficiently simple and cost-effective to deploy. I demonstrate the validity of the microcosm system and discuss in-progress work which demonstrates its potential to rigorously investigate unknown aspects of the plant-AMF mutualism. Taken together, these developments and suggestions contribute to the growing set of methods and frameworks developed for improving our understanding a various plant-biotic interactions.
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Title: CLICKABLE POLY(PROPARGYL METHACRYLATE) PREPARED BY ATOM TRANSFER RADICAL POLYMERIZATION AND ITS DERIVATIVES AS ENZYME STABILIZERS
Creator: Hsiao, Po-Jen
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Enzymes are nearly perfect catalysts with excellent selectivity and high turnover frequencies. A long-standing goal has been enabling enzymes to operate ex vivo in non-aqueous solvents, but the structures of native enzymes are typically compromised under these conditions. Polymer-enzyme bioconjugates have shown some promise—albeit limited—in this regard. The clickable poly(propargyl methacrylate) (PPMA) was proposed as a platform to enhance different polymer structures versus the residual...
Show moreEnzymes are nearly perfect catalysts with excellent selectivity and high turnover frequencies. A long-standing goal has been enabling enzymes to operate ex vivo in non-aqueous solvents, but the structures of native enzymes are typically compromised under these conditions. Polymer-enzyme bioconjugates have shown some promise—albeit limited—in this regard. The clickable poly(propargyl methacrylate) (PPMA) was proposed as a platform to enhance different polymer structures versus the residual enzymatic activities. The degree of polymerization and polydispersity are two factors that affect the polymer properties and can affect the enzymatic activities of the polymer-enzyme bioconjugates. The literature examples of PPMA with degree of polymerization greater than 200 are limited. In the atom transfer radical polymerization (ATRP) conditions we discovered, the degree of polymerization and the polydispersity of poly(trimethylsilylpropargyl methacrylate) (PTMSPMA) can be precisely adjusted by the initiator and monomer ratio, the copper catalyst loading, and the reducing agent loading (copper wire). After deprotection, PPMA is further reacted with different mole fraction compositions of hydrophilic triethylene glycol monomethyl ether (mDEG) azide and hydrophobic dodecyl azide to prepare amphiphilic polymers as enzyme stabilizers. The activities of the model enzyme, Subtilisin Carlsberg (SC), and polymer-SC bioconjugates were determined by 4-nitrophenolate and 4-thiopyridone assays, and the polymer-enzyme bioconjugate SC@82%mDEG-PPMA was found to be more active than SC alone in toluene. The SC@82%mDEG-PPMA is also more active than SC@100%mDEG-PPMA in 4-nitrophenolate assay, proving that the side chain structure of the polymer micelles can affect the polymer-enzyme bioconjugates. The micelle 80%mDEG-PPMA may isolate the enzyme from the bulk toluene better than 100%mDEG-PPMA. Deprotonated amino acid salts are great alternatives to the synthesized alkylamines as post-combustion CO2 absorbents due to their non-toxic and low volatile nature. For CO2 capture, gas uptake was measured when solutions of monodeprotonated amino acids were sparged with CO2. The speciation between dissolved CO32–, HCO3– , and CO2(aq), and CO2 captured as carbamates of the deprotonated amino acids, was quantified by 13C{1H} and 1H NMR spectroscopy. Less hindered amino acids like glycine tend to have faster CO2 absorption kinetic and higher carbamate concentrations due to the formation of relatively stable carbamates. One equivalent of carbamate forms requires one equivalent of amino acid as sacrificial base. Therefore, the formation of carbamate decreases the total CO2 absorption capacity and is an unfavorable pathway for CO2 capture. While the amino acids containing substituents at the α carbon atom adjacent to the amino group, like alanine and proline, destabilize their carbamates by unfavorable steric interaction and lead to carbamate hydrolysis to CO32–/HCO3– and enhance the CO2 capture capacity. Therefore, mixing different amino acids can have the fast absorption kinetics and higher absorption capacity. Based on the results, the mixture amino acid solutions were observed to have higher CO2 absorption capacity than the single amino acid counterparts.
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Title: RECREATIONAL CANNABIS LEGALIZATION : PREDICTING LOCAL POLICY ADOPTION AND ESTIMATING THE ASSOCIATED EFFECTS ON POPULATION CANNABIS USE
Creator: Montgomery, Barrett Wallace
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Cannabis is undergoing a remarkable transformation from a regulated drug to a recreationally legal one in the United States (U.S.). Yet, in states that have legalized recreational cannabis, there is substantial geographic variability in actual cannabis policies and the effects of cannabis legalization are still being debated. This dissertation addresses these modern scientific issues of the recreational cannabis landscape. The population under study primarily includes non-institutionalized U...
Show moreCannabis is undergoing a remarkable transformation from a regulated drug to a recreationally legal one in the United States (U.S.). Yet, in states that have legalized recreational cannabis, there is substantial geographic variability in actual cannabis policies and the effects of cannabis legalization are still being debated. This dissertation addresses these modern scientific issues of the recreational cannabis landscape. The population under study primarily includes non-institutionalized U.S. civilian residents, sampled and assessed in successive waves of the National Survey on Drug Use and Health (NSDUH) starting in 2008 through 2019. Estimates on drug use and mental illness prevalences are aggregated to the county level for the first aim, and to the state level for the second and third aims. In the first aim, the county-level data are linked to several other publicly available sources of information on all 3,142 U.S. counties including the 2010 Census, 2012 presidential election, and recreational cannabis sales policies. I then used these data to train a machine learning algorithm to predict which counties allowed for the recreational sale of cannabis in 2014. In the second aim, I used state-level estimates of cannabis incidence in an event study model to estimate the effects of legalizing recreational cannabis on cannabis use onsets for persons under and over the legal minimum age of 21. The final aim focuses specifically on 21 year-olds to better understand the implications for setting a legal minimum age drug policy on age-specific patterns of incidence and proposes a theoretical framework that may help understand these findings. For the first aim, the model-averaging predictions classified almost 94% of the U.S. counties correctly. The main factors associated with county-level recreational cannabis laws were the prevalences of past-month cannabis use and past-year cocaine use. In the second aim, I found that for those who were legally able to purchase cannabis (21 and older), cannabis legalization did not appear to affect incidence in the first year following legalization. Even so, between two and four years after legalization, the difference in differences modeling disclosed statistically robust increases of 0.6% for this sub-population of adults. After four years, the estimated increase is 1.3%. The corresponding estimates for underage persons who were ineligible to legally purchase cannabis show no appreciable differences in the occurrence in past-year cannabis use incidence. Finally, the age-specific incidence estimates for 21-year-olds show a rise after the passage of recreational cannabis laws (RCL) and are suggestive of the arrival of a new pattern of age-specific incidence. Taken together, the work and results of this dissertation point toward four potential conclusions. First, cannabis legalization might depend on a predictable process driven in part by prior drug use in each jurisdiction. Second, once implemented, recreational cannabis legalization might not have effects on adolescent onset newly incident cannabis use. Third, for adults permitted to buy cannabis without penalty, the occurrence of newly incident cannabis use might increase. Fourth, a tentative conclusion is that legalization of retail sales to adults removes a barrier for adults who had been interested in trying cannabis, but did not do so, perhaps due to concerns about legal or social consequences faced before legalization.
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Title: The Geography and Recent Activity of Lake Michigan’s Coastal Sand Dunes
Creator: McKeehan, Kevin G.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation attempts to fill a gap in knowledge regarding conditions amongst the dunefields of Lake Michigan’s eastern shore. Much is now known about the evolution and geochronology of these unique freshwater dune systems. The region’s coastal dunes began forming during the Nipissing high stand phase (~5.5ka) of ancestral Lake Michigan. Since then, according to the chronology constructed from several studies, the coastal dunes then underwent several periods of stability and instability...
Show moreThis dissertation attempts to fill a gap in knowledge regarding conditions amongst the dunefields of Lake Michigan’s eastern shore. Much is now known about the evolution and geochronology of these unique freshwater dune systems. The region’s coastal dunes began forming during the Nipissing high stand phase (~5.5ka) of ancestral Lake Michigan. Since then, according to the chronology constructed from several studies, the coastal dunes then underwent several periods of stability and instability along the entire shoreline. However, questions remain regarding dune conditions and variability since ~1900. The goal of this dissertation was to determine if changes have occurred to the region’s coastal dune systems in the last ~120 years and what might be driving those changes. Given that dune systems are sensitive to biotic and abiotic variables, examining the last ~120 years of dune behavior could potentially reveal how Lake Michigan coastal dunes are responding to anthropogenic climate change and human development.Three studies, each comprising a dissertation chapter (Chapters 2-4), were conducted to help close this knowledge gap. Each chapter is broadly linked through an ecogeomorphic lens, particularly through the relationship between dunes and vegetation, which are interconnected in important ways. In Chapter 2, changes in dunefield vegetation and morphology were determined at several locations along the eastern Lake Michigan shoreline through the use of ground-level repeat photography. The second dissertation study – Chapter 3 – concerns the spatiotemporal analysis of historical changes of blowouts, which are important indicators of significant disturbance in the dunes. In this chapter, blowouts were mapped from aerial images at three timestamps – 1938, 1986-8, and 2018 – and the changes quantified. Chapter 4, the final dissertation study, explores the relationship between terrain ruggedness and vegetation in a coastal dunefield along Lake Michigan by calculating two terrain indices – Riley’s Terrain Ruggedness Index (TRI) and Sappington’s Vector Ruggedness Measure (VRM) – and the Soil-Adjusted Vegetation Index (SAVI). Through a land systems framework, the results were compared to determine if any correlation exists between the ruggedness of dunes and vegetation.In the first two dissertation studies, the results show a clear expansion of vegetation at the expense of previously bare sand. In the final study, the values from TRI and VRM and the values from the Soil-Adjusted Vegetation Index (SAVI) were not correlated overall, especially where one type of vegetation was dominant. However, within one land system – the dune barrens -- a moderate-to-strong negative correlation existed between terrain ruggedness and vegetation. Moreover, evidence suggests that vegetation has transformed the dune barrens land system area within the modern period. Overall, the results of these three studies demonstrate that vegetation is expanding over previously bare surfaces in coastal dunes along the eastern shore of Lake Michigan and has a considerable influence on regional dune conditions. While the precise driver(s) of this transformation is unclear, the regional-scale nature of these results suggests a uniform control is affecting these changes. As described in this dissertation, it is possible that an increase in precipitation since the 1930s, elevated atmospheric CO2 and N concentrations, a reduction in wind power, some other change in climate drivers, or a combination of many factors is responsible for the expansion in vegetation. It is also possible the trend in vegetation growth in Lake Michigan’s coastal dunes is a lagged response to an earlier climate event.
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Title: The water-energy-food nexus assessments of carbon neutral efforts
Creator: Xie, Yachen
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Efforts toward carbon neutrality are crucial for humans' well-being and the environment. Currently, two main ongoing carbon mitigation efforts are enhancing carbon sequestration and reducing carbon emissions. However, there are debates regarding the tradeoffs of these two efforts' related policies and action plans. This dissertation investigates and assesses the tradeoffs of carbon neutral efforts from a WEF nexus perspective. Three typical efforts were selected as assessment targets to...
Show moreEfforts toward carbon neutrality are crucial for humans' well-being and the environment. Currently, two main ongoing carbon mitigation efforts are enhancing carbon sequestration and reducing carbon emissions. However, there are debates regarding the tradeoffs of these two efforts' related policies and action plans. This dissertation investigates and assesses the tradeoffs of carbon neutral efforts from a WEF nexus perspective. Three typical efforts were selected as assessment targets to answer the overarching question of how carbon neutral efforts would affect the water-energy-food (WEF) nexus. The Chinese conversion of cropland to forestland program (CCFP) is representative of carbon sequestration. The hydropower development in MRB is an example of the energy transition to reduce emissions. The coal power industry is the coupling effort of energy transition and carbon capture, utilization, and storage (CCUS) applications in reducing carbon emissions. This dissertation consists of three main chapters, each corresponding to a journal article to address the three assessment targets. In Chapter 2, I evaluated the accomplishment of CCFP in China and its WEF nexus tradeoffs by applying remote sensing images from 2001 to 2019. The WEF assessment includes the transition matrix generation and the water yield calculation of the converted cropland and irrigation land. Indices related to WEF systems are also considered. In Chapter 3, a diagnostic approach with ten indicators was developed to assess the unilateral change's impacts on the WEF nexus. Using the diagnostic method, I provided statistical evidence of the benefits and tradeoffs of water, energy, food, economic prosperity, and the environment surrounding hydro dams in the Mekong River Basin. In Chapter 4, a scenario-based, life cycle coal power production assessment tool was proposed. By evaluating three portfolios or scenarios, the tradeoffs between reducing coal power production and CCUS application were revealed. This dissertation has successfully assessed the primary tradeoffs of carbon mitigation efforts from the WEF nexus perspective. The three studies can be wrapped up and come to three major conclusions: 1) The cons of major carbon mitigation efforts on WEF nexus and local sustainability exist, but not as speculated, especially for the CCFP and the hydropower dam construction. 2) The carbon neutral policies in China can accomplish their goals if adequately implemented. 3) The adaptive equilibrium between the CCUS application and coal power production reduction in China is crucial and needs to be better planned. The dissertation can enrich the carbon neutrality debate and fill gaps in the current literature on WEF nexus tradeoff studies on carbon mitigation by providing a remote-sensing approach and detailed coal modeling tools. The assessment tools proposed in Chapters 3 and 4 can be widely used by policymakers to understand better the tradeoffs regarding sustainability and WEF nexus in carbon neutral efforts.
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Title: CRANIAL METRIC AND NONMETRIC VARITION IN SOUTHEAST MEXICO AND GUATEMALA : IMPLICATIONS FOR POPULATION AFFINITY ASSESSMENT IN THE UNITED STATES
Creator: Kamnikar, Kelly Rae
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The scientific identification of unknown human skeletal remains in forensic contexts relies heavily on the estimation of demographic parameters (i.e., sex, age, stature, and population affinity). Population affinity, or the likelihood of group relatedness to a defined population of a decedent, can be estimated using measurements and observations from the cranial and postcranial skeleton. These estimations may be less accurate among populations which have been pooled together based on...
Show moreThe scientific identification of unknown human skeletal remains in forensic contexts relies heavily on the estimation of demographic parameters (i.e., sex, age, stature, and population affinity). Population affinity, or the likelihood of group relatedness to a defined population of a decedent, can be estimated using measurements and observations from the cranial and postcranial skeleton. These estimations may be less accurate among populations which have been pooled together based on convention. Latin American individuals—with geographic origins widely distributed throughout Central and South America—are broadly pooled together under the blanket term Hispanic with little regard for the immense cultural and biological diversity represented by these groups. Consequently, forensic anthropologists may be unintentionally disregarding genetic diversity, population structure, and population history and their impact on the formation and morphology of these groups. The purpose of this dissertation is to investigate variation in craniofacial morphology and develop population affinity models for Latin American groups using cranial metric and nonmetric data. The intent is to move beyond a single classification level (i.e., Hispanic) to more refined levels based on geographic origins (e.g., Guatemala, Southeast Mexico). The broad category of Hispanic was adopted by forensic anthropologists in large part because it is still used in medicolegal death investigations in the U.S. to describe individuals with familial origins in Latin America, Spain, and the Caribbean (U.S. Census Bureau 2021). Since the term Hispanic does not narrow down the region of origin for unidentified human remains, it is uninformative for identification and repatriation purposes, particularly regarding forensic investigations along the southern U.S. border. In this context, population affinity estimation benefits from refinement of a broad category to a more focused, population-level group. Craniometric and cranial macromorphoscopic (MMS) data are collected from samples in Guatemala City, Guatemala and Mérida, Mexico—with strong support from the forensic anthropologists in these countries—to capture aspects of skeletal variation associated with these regions. Biological distance and population affinity models are assessed and comparative data from other Latin American and U.S. populations are used to assess how well these model skeletal variation. Biological distance analysis demonstrates that Latin American populations, including the Meridian and Guatemala sample are distinct. Classification models obtain varying accuracy rates; the combined craniometric and cranial MMS model had the highest classification accuracy (70.7%). This study provides further support for the refinement of this broad category and is important for future investigations involved in identification efforts along the U.S.-Mexico border.
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Title: HOW CAREGIVERS OF CHILDREN IN EARLY INTERVENTION FEEL ABOUT SIMPLIFIED LANGUAGE INPUT : A SURVEY STUDY
Creator: Nylund, Megan
Date: 2022
Collection: Electronic Theses & Dissertations
Description: There is some disagreement regarding how adults should simplify their utterances when speaking to young children with language delays. One type of simplification that has come into question is telegraphic input, a style of speaking that involves removing grammatical aspects of phrases, such as function words and grammatical markers (e.g., All done snack, Cookie yummy). In the current study, we utilized survey data collected by Andary (2020) surveying caregivers of children in early...
Show moreThere is some disagreement regarding how adults should simplify their utterances when speaking to young children with language delays. One type of simplification that has come into question is telegraphic input, a style of speaking that involves removing grammatical aspects of phrases, such as function words and grammatical markers (e.g., All done snack, Cookie yummy). In the current study, we utilized survey data collected by Andary (2020) surveying caregivers of children in early intervention about their views on different types of simplified language. Specifically, we asked: How do caregivers’ beliefs about telegraphic input relate to how comfortable they are producing different types of simplified utterances? Results were also analyzed for correlations between demographics and beliefs of simplification. Additionally, the survey provided space for caregivers to share recommendations they gained through Early On resources. Results show caregivers with a positive view of telegraphic input felt significantly less comfortable producing full, grammatical utterances than caregivers with a negative or neutral view of telegraphic input. Demographic analysis revealed caregivers with higher education levels preferred more grammatical utterances. These findings emphasize the importance of understanding caregiver perspectives in caregiver-mediated intervention approaches.
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Title: Circuit-Specific Inhibition of Dopaminergic Signaling Associated with Phantom Gustatory Sensations in Disrupted-in-Schizophrenia-1 Mice
Creator: Fry, Benjamin R.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Schizophrenia is a severe neuropsychiatric disorder characterized by a suite of symptoms occurring across cognitive (delayed processing, paraphasia, attentional deficits), negative (anhedonia, blunted affect, catatonia), and positive (hallucinations, delusions) domains. Antipsychotics are the most commonly prescribed medication to treat positive symptoms, however their use is complicated by substantial side-effects and inadequate efficacy. This reflects a lack of progress in understanding the...
Show moreSchizophrenia is a severe neuropsychiatric disorder characterized by a suite of symptoms occurring across cognitive (delayed processing, paraphasia, attentional deficits), negative (anhedonia, blunted affect, catatonia), and positive (hallucinations, delusions) domains. Antipsychotics are the most commonly prescribed medication to treat positive symptoms, however their use is complicated by substantial side-effects and inadequate efficacy. This reflects a lack of progress in understanding the precise neurobiological mechanisms underlying these symptoms, due in part to a lack of appropriate preclinical animal models. Here, I used an animal model of genetic vulnerability for neuropsychiatric illness known as Disrupted-in-schizophrenia-1 (DISC-1) to examine impaired reality testing, which reflects an aberrant internal representation of an absent event. In mice, this can be observed by an associatively evoked perception of an absent sweet taste. This effect is dopaminergically-dependent and associated with elevated activity in the insular cortex (IC). By combining sophisticated Pavlovian behavioral procedures with chemogenetic inhibition of dopamine neurons projecting from the ventral tegmental area (VTA) to the IC, I show that inactivation of the VTA --> IC dopaminergic circuitry leads to impaired reality testing in wild-type mice, and that DISC-1 mice have significantly less dopamine neurons which send projections to the IC, specifically. These data yield new insights with regard to the neurobiology underlying reality testing and the functional anatomical outcomes following perturbations of the DISC-1 genetic locus. My studies also suggest potential targets for the development of novel pharmacological treatments in humans with schizophrenia.
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Title: EXPRESSION AND ROLES OF BLASTOCYST LINEAGE-DETERMING GENES DURING SOMATIC CELL REPROGRAMMING
Creator: Moauro, Alexandra
Date: 2022
Collection: Electronic Theses & Dissertations
Description: In order to properly use stem cells, it is important that we first understand how these cells are establish and maintained. One of the most widely used stem cells are induced pluripotent stem cells (iPSCs) which provide great therapeutic promise and a novel source of ethical stem cells for research models. iPSCs are created by overexpression Oct4, Sox2, Klf4 and c-Myc (OSKM) in a somatic cell. As studies have sought to improve reprogramming efficiency and develop the most embryonically...
Show moreIn order to properly use stem cells, it is important that we first understand how these cells are establish and maintained. One of the most widely used stem cells are induced pluripotent stem cells (iPSCs) which provide great therapeutic promise and a novel source of ethical stem cells for research models. iPSCs are created by overexpression Oct4, Sox2, Klf4 and c-Myc (OSKM) in a somatic cell. As studies have sought to improve reprogramming efficiency and develop the most embryonically identical stem cells, our lab has uncovered that OSKM is not a specific cocktail for pluripotency formation. Instead OSKM induces additional cell fates including the formation of a multipotent stem cell termed induced extraembryonic endoderm stem (iXEN) cells. This raises the question as to how two distinct stem cell types arise in parallel. Interestingly, in embryo development we observe the same pluripotent and multipotent extraembryonic endoderm lineages form in parallel. Using our knowledge of normal embryo development, I set out to identify what blastocyst lineage markers can help us identify early iPSC and iXEN colonies as they start to form and mature. Of these markers, we observed that endogenous OCT4 is expressed in both iXEN and iPSC colonies. Based on the expression pattern of the key embryonic transcription factor, OCT4, we further focused on how this transcription factor may have a dual role in establishing iPSC and iXEN fates. Lastly, we altered the reprogramming cocktail using additional embryonic transcription factors to determine how these factors affect the propensity for pluripotency or extraembryonic endoderm fate.
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Title: Deterministic and Semi-Stochastic CC(P;Q) Approaches : New Developments and Applications to Spectroscopy and Photochemistry
Creator: Yuwono, Stephen Haniel
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The development of electronic structure methods that can accurately describe ground and excited states of molecular systems with manageable computational costs and in a systematically improvable manner continues to be the central theme of quantum chemistry. This dissertation focuses on some of the recent developments in the coupled-cluster (CC) theory and its equation-of-motion (EOM) extension to excited electronic states. One of the key challenges in the development of the CC and EOMCC...
Show moreThe development of electronic structure methods that can accurately describe ground and excited states of molecular systems with manageable computational costs and in a systematically improvable manner continues to be the central theme of quantum chemistry. This dissertation focuses on some of the recent developments in the coupled-cluster (CC) theory and its equation-of-motion (EOM) extension to excited electronic states. One of the key challenges in the development of the CC and EOMCC methodologies is the incorporation of many-electron correlation effects due to higher-rank components of the cluster and EOM excitation operators without incurring significant increase in the computational costs, while avoiding failures of perturbative methods of the CCSD(T) type in multireference situations, such as bond breaking and excited states dominated by two-electron transitions, and in certain weakly bound systems. Among the best ways to address these issues is the CC(P;Q) framework, which provides robust and computationally affordable noniterative energy corrections to lower-order CC/EOMCC calculations. In this dissertation, we discuss the different CC(P;Q) variants relying on both the conventional and unconventional truncations in the cluster and EOM excitation operators. The advantages of the CC(P;Q) hierarchy are illustrated using a few examples ranging from small molecule spectroscopy to photochemistry of large organic species in solution. In particular, we discuss the computational investigations of the novel super photobase FR0-SB, which exhibits a drastic increase in basicity upon photoexcitation, including the energetics and properties of its excited states, the steric effects governing the excited-state proton transfer involving FR0-SB and alcohols, and the enhanced photoreactivity of FR0-SB resulting from two-photon excitations, where the δ-CR-EOMCC(2,3) approach that belongs to the CC(P;Q) hierarchy played a key role. Furthermore, we demonstrate that the relatively inexpensive CC(t;3) and CC(q;4) approaches derived from the CC(P;Q) framework are as accurate in describing the challenging weakly bound magnesium dimer, including its ground-state potential and vibrational levels supported by it, as the much more demanding CCSDT and CCSDTQ parent theories. We also show how the highly accurate ground- and excited-state ab initio potentials obtained in the state-of-the-art CCSDT, CR-EOMCCSD(T), and full configuration interaction (CI) computations allowed us to resolve the existing laser-induced fluorescence and photoabsorption spectra of the magnesium dimer and find the missing high-lying vibrational states of Mg2 that have eluded scientists for half a century. Last, but not least, we discuss our recent extension of the semi-stochastic CC(P;Q) framework, which combines the deterministic CC(P;Q) theory with stochastic CI quantum Monte Carlo (QMC), to excited electronic states, providing rapid convergence to the parent high-level EOMCC methods, such as EOMCCSDT, out of the early stages of QMC propagations. The advantages of the semi-stochastic CC(P;Q) approach targeting EOMCCSDT are illustrated by examining vertical excitations in CH+ and adiabatic excitations in the CH and CNC species.
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Title: Three Essays on Panel Data Models with Interactive and Unobserved Effects
Creator: Brown, Nicholas Lynn
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Chapter 1: More Efficient Estimation of Multiplicative Panel Data Models in the Presence of Serial Correlation (with Jeffrey Wooldridge)We provide a systematic approach in obtaining an estimator asymptotically more efficient than the popular fixed effects Poisson (FEP) estimator for panel data models with multiplicative heterogeneity in the conditional mean. In particular, we derive the optimal instrumental variables under appealing `working' second moment assumptions that allow...
Show moreChapter 1: More Efficient Estimation of Multiplicative Panel Data Models in the Presence of Serial Correlation (with Jeffrey Wooldridge)We provide a systematic approach in obtaining an estimator asymptotically more efficient than the popular fixed effects Poisson (FEP) estimator for panel data models with multiplicative heterogeneity in the conditional mean. In particular, we derive the optimal instrumental variables under appealing `working' second moment assumptions that allow underdispersion, overdispersion, and general patterns of serial correlation. Because parameters in the optimal instruments must be estimated, we argue for combining our new moment conditions with those that define the FEP estimator to obtain a generalized method of moments (GMM) estimator no less efficient than the FEP estimator and the estimator using the new instruments. A simulation study shows that the GMM estimator behaves well in terms of bias, and it often delivers nontrivial efficiency gains -- even when the working second-moment assumptions fail.Chapter 2: Information equivalence among transformations of semiparametric nonlinear panel data modelsI consider transformations of nonlinear semiparametric mean functions which yield moment conditions for estimation. Such transformations are said to be information equivalent if they yield the same asymptotic efficiency bound. I first derive a unified theory of algebraic equivalence for moment conditions created by a given linear transformation. The main equivalence result states that under standard regularity conditions, transformations which create conditional moment restrictions in a given empirical setting need only to have an equal rank to reach the same efficiency bound. Example applications are considered, including nonlinear models with multiplicative heterogeneity and linear models with arbitrary unobserved factor structures.Chapter 3: Moment-based Estimation of Linear Panel Data Models with Factor-augmented ErrorsI consider linear panel data models with unobserved factor structures when the number of time periods is small relative to the number of cross-sectional units. I examine two popular methods of estimation: the first eliminates the factors with a parameterized quasi-long-differencing (QLD) transformation. The other, referred to as common correlated effects (CCE), uses the cross-sectional averages of the independent and response variables to project out the space spanned by the factors. I show that the classical CCE assumptions imply unused moment conditions which can be exploited by the QLD transformation to derive new linear estimators which weaken identifying assumptions and have desirable theoretical properties. I prove asymptotic normality of the linear QLD estimators under a heterogeneous slope model which allows for a tradeoff between identifying conditions. These estimators do not require the number of cross-sectional variables to be less than T-1, a strong restriction in fixed-$T$ CCE analysis. Finally, I investigate the effects of per-student expenditure on standardized test performance using data from the state of Michigan.
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Title: Subgenome dominance and genome evolution in allopolyploids
Creator: Bird, Kevin Andrew
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The merger of divergent genomes, via hybridization or allopolyploidization, frequently results in a ‘genomic shock’ that induces a series of rapid genetic and epigenetic modifications as a result of conflicts between parental genomes. This conflict among the subgenomes routinely leads one subgenome to become dominant over the other subgenome(s), resulting in subgenome biases in gene content and expression. Recent advances in methods to analyze hybrid and polyploid genomes with comparisons to...
Show moreThe merger of divergent genomes, via hybridization or allopolyploidization, frequently results in a ‘genomic shock’ that induces a series of rapid genetic and epigenetic modifications as a result of conflicts between parental genomes. This conflict among the subgenomes routinely leads one subgenome to become dominant over the other subgenome(s), resulting in subgenome biases in gene content and expression. Recent advances in methods to analyze hybrid and polyploid genomes with comparisons to extant parental progenitors have allowed for major strides in understanding the mechanistic basis for subgenome dominance. In particular, our understanding of the role that homoeologous exchange might play in subgenome dominance and genome evolution is quickly growing. Here I present novel work in several polyploid species investigating the biological and evolution impact of polyploidy and the evolution of these polyploid species. The first chapter introduces concepts like whole-genome duplication and describes advances in genomic sequencing technology that have accelerated the study of polyploid genomes. The second chapter reviews subgenome dominance and recent breakthroughs in understanding its causes and implications for genome evolution. The third chapter explores the repeatability of subgenome dominance in independently resynthesized Brassica napus. The fourth chapter investigates the extent to which genomic rearrangements from chromosomal duplications and deletions and homoeologous exchange can bias the analysis of subgenome expression dominance from RNAseq data. The fifth chapter explores the prevalence and impact of homoeologous exchange on independently resynthesized Brassica napus, providing novel evidence that gene dosage changes from homoeologous exchange are constrained by the need to maintain dosage balance of gene products. The sixth chapter explores the origins and admixture of wild octoploid strawberries Fragaria virgniana and Fragaria chiloensis with newly generated genomic resources applied to global collections.
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