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Title: A method for determining seed viability by electrical conductivity measurements
Creator: Fick, George L.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: On the inheritance of flower color in alfalfa
Creator: Robinson, Brittain B.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: Proposed drainage of Faye Lake, Jackson co., Michigan
Creator: Moore, Willard O.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: Shrinkage of live stock in transit
Creator: Bovay, Arthur G.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: Investigation of the water supply system of Jackson, Michigan, with recommendations for future improvements
Creator: Johnson, William C.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: The leaf spot disease of muskmelon
Creator: Cole, John R.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: Effect of calcium chloride on plain and reinforced concrete
Creator: Black, Roscoe J.
Date: 1924
Collection: Electronic Theses & Dissertations

Title: UNDERSTANDING THE ROLES OF INTERKINGDOM MICROBIAL INTERACTIONS, MICROBIAL TRAITS, AND HOST FACTORS IN THE ASSEMBLY OF PLANT MICROBIOMES
Creator: Liber, Julian Aaron
Date: 2021
Collection: Electronic Theses & Dissertations
Description: The community of organisms that associate with plants are vital to both the survival of the host plant but also the diseases which may kill it. The processes by which this community, called the microbiome, assemble and function can contribute to the traits of the host, including plants that humans rely on for food, resources, and ecosystems services. This thesis focuses on understanding the assembly of microbiomes at the scale of microbe-microbe interactions and traits of individual microbes,...
Show moreThe community of organisms that associate with plants are vital to both the survival of the host plant but also the diseases which may kill it. The processes by which this community, called the microbiome, assemble and function can contribute to the traits of the host, including plants that humans rely on for food, resources, and ecosystems services. This thesis focuses on understanding the assembly of microbiomes at the scale of microbe-microbe interactions and traits of individual microbes, as well as how characters of the host may change this process. I first address this by examining the in vitro and in planta interactions within small synthetic communities of root-inhabiting bacteria and fungi and with the plant host and viral disease of the host. While intermicrobial interactions in vitro were not predictive of in planta interactions, adding host disease or additional organisms to the system altered the assembly process. I then show the development and applications of the CONSTAX2 classifier, a taxonomic assignment tool for metabarcoding studies, which offers improved accuracy and ease of use for conducting metabarcoding studies exploring the diversity and structure of microbial communities. Last, I present a study testing which factors affected the composition of forest fungal communities to understand the ecology of litter-inhabiting fungi and improve methodologies for sampling leaf-associated fungal communities. The factors affecting the assembly of plant microbiomes are complex and varied but connecting individual interactions to community composition and ultimately function may improve our abilities to predict and manage microbiome processes.
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Title: A PEDAGOGICAL FUSION RECIPE : AN EXPLORATION OF TEACHERS’ AND CHEFS’ CREATIVITY IN PRACTICE THROUGH THE USE OF RESOURCES
Creator: Evalt, Samuel
Date: 2021
Collection: Electronic Theses & Dissertations
Description: In this dissertation, I explored creativity in practice. I ask: 1) How do the participants define creativity?; 2) In what way does creativity reflect the positioning between actor and resource?; 3) What creative practices emerge when individuals choose to use, or not use, resources?; 4) How do resources mediate creativity? To understand creativity in practice, I used a case study featuring eight participants across two fields, four teachers and four chefs. The two fields provided a way to...
Show moreIn this dissertation, I explored creativity in practice. I ask: 1) How do the participants define creativity?; 2) In what way does creativity reflect the positioning between actor and resource?; 3) What creative practices emerge when individuals choose to use, or not use, resources?; 4) How do resources mediate creativity? To understand creativity in practice, I used a case study featuring eight participants across two fields, four teachers and four chefs. The two fields provided a way to understand and build a comparative case study about creativity in practice through the use of resources. I interviewed and collected digital artifacts from the participant teachers and chefs. The interviews were transcribed. Then I used qualitative coding to analyze the interview and artifact data. The findings revealed nuanced elements of creativity in practice and resources, which reflected layered voices. The findings highlighted of recreative and creative practices. And more importantly, resources mediated creativity in practice to illustrate the nexus of creativity in practice. I framed creativity as a sociocultural practice and an epistemological construction rather than cognitive and ontologically based. I argue that creativity in practice is messy. Films and media portray a mythology of creativity as a cognitive and ontological construction of individual genius. The teachers and chefs shared narratives that reflected the reality of creativity as messy through the layers of learning and practices. Resources represent the mediator for learning and practices. It is through resources that creators can strengthen their nexus of creativity in practice in critical or non-critical ways. Ultimately, the significance of the research helps deconstruct creativity in practice to make visible the challenges and messiness for all creators.
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Title: HOW DO MANAGEMENT DECISIONS IMPACT THE SUSTAINABILITY OF UPPER MIDWEST BEEF CATTLE GRAZING?
Creator: Thompson, Logan Riley
Date: 2021
Collection: Electronic Theses & Dissertations
Description: The conversion of grass to beef is less efficient than the process of converting feed to human-edible protein in nonruminants, although ruminal fermentation does allow for the utilization of complex carbohydrates. This has resulted in the cattle industry receiving increased attention due to its perceived high carbon (C) footprint. While ruminants have evolved to fill the niche of converting human inedible carbohydrates into usable end-products for growth, this process results in considerable...
Show moreThe conversion of grass to beef is less efficient than the process of converting feed to human-edible protein in nonruminants, although ruminal fermentation does allow for the utilization of complex carbohydrates. This has resulted in the cattle industry receiving increased attention due to its perceived high carbon (C) footprint. While ruminants have evolved to fill the niche of converting human inedible carbohydrates into usable end-products for growth, this process results in considerable greenhouse gas (GHG) emissions as byproducts of the reticulo-rumen fermentation process. Life Cycle Assessments have shown that the grazing sector of the cattle industry, cow-calf and stocker cattle, may be responsible for 70 to 80% of the industry’s total C footprint. Therefore, research is needed to explore the soil-plant-animal interrelationships and generate data to provide management recommendations to producers to improve the C footprint of their operation. As it relates to agriculture, sustainability has three legs that must be met addressed to improve its sustainability: 1) social- the strategy must maintain social license to operate, 2) environmental- the strategy must reduce negative environmental consequences, and 3) economic- producers must remain economically viable. This dissertation examines how management decisions impact grazing beef cattle through two of the three legs of sustainability: environmental and economic sustainability. The literature review focuses on the role on enteric methane on the C footprint of the beef industry, as this topic “keeps the lights on” in many laboratories due to increased consumer concern about the industry’s C footprint. However, key nutritional abatement strategies that goes beyond enteric methane are management decisions that improve the efficiency of ruminal fermentation. Matching cows to the production environment is a critical management decision, as selecting cows too small or too large would result in an inefficient utilization of the forage base. This idea is explored chapter 2, modeling the biological and economic output of a Michigan beef herd. We conducted a backwards looking enterprise budget analysis and forward-looking net present value analysis on the Lake City AgBioResearch Center Red Angus herd to determine what size cow best fits the present production environment. We found that as cow size increased, within the range of cow body weights of 430.83 to 634.92 kg, calculated net returns per unit of land decreased by $10.27/ha. The last two chapters compare environmental tradeoffs between two different forage mixtures grazed by beef cattle: a biologically diverse, mixed-specie pasture (COMP), and a simple binary mixture of alfalfa:orchardgrass (SIMP). The hypothesis was that the COMP mixture would have reduced enteric methane production, increased forage productivity due to the diversity of the mixture, and greater soil C accumulation. Both treatments performed similarly in animal performance, soil GHG fluxes, and soil organic C and total N stocks. Animals grazing COMP mixtures tended to have lower enteric CH4 emissions compared to SIMP, but there was no difference in emission intensity across three grazing seasons. This project serves to supplement the dearth of literature comparing a simple and diverse forage mixture. More research on the long-term performance of the diverse and simple forage mixtures and the utilization of new technologies such as eddy covariance flux towers will help provide a more robust examination on the environmental tradeoffs between forage mixtures than the methodologies utilized in this experiment.
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Title: Single-Reference Coupled-Cluster Methods for Strongly Correlated Systems
Creator: Magoulas, Ilias
Date: 2021
Collection: Electronic Theses & Dissertations
Description: The development of computationally efficient wavefunction methods that can provide an accurate description of strongly correlated systems and materials is at the heart of electronic structure theory. In general, strong many-electron correlation effects arise from the entanglement of a large number of electrons and are characterized by the unpairing of many electron pairs and their subsequent recoupling to low-spin states, as in the case of Mott metal-insulator transitions where the system...
Show moreThe development of computationally efficient wavefunction methods that can provide an accurate description of strongly correlated systems and materials is at the heart of electronic structure theory. In general, strong many-electron correlation effects arise from the entanglement of a large number of electrons and are characterized by the unpairing of many electron pairs and their subsequent recoupling to low-spin states, as in the case of Mott metal-insulator transitions where the system traverses from a weakly correlated metallic phase to a strongly correlated insulating one. Although strong correlations have an intrinsically multi-reference nature, multi-reference approaches are not applicable due to the enormous dimensionalities of the underlying model spaces. Therefore, in this dissertation, we focus on single-reference coupled-cluster (CC) approaches, which are widely recognized as the de facto standard for high-accuracy electronic structure calculations and whose size extensivity makes them suitable for the study of extended systems and materials. However, it is well established that the traditional CC methodologies that are based on truncating the cluster operator at a given many-body rank, giving rise to the CCSD, CCSDT, CCSDTQ, etc. hierarchy, fail to provide physically meaningful solutions in the presence of strong correlations. Thus, in this dissertation, we consider unconventional single-reference CC approaches capable of providing an accurate description of the entire spectrum of many-electron correlation effects, ranging from the weakly to the strongly correlated regimes.In the first part of this dissertation, we examine the approximate coupled-pair (ACP) theories. The existing ACP methods and their various modifications retain all doubly excited cluster amplitudes, while using subsets of non-linear diagrams of the CCD/CCSD equations. This eliminates failures of conventional CC approaches, including CCSD and even CCSDT or CCSDTQ, in strongly correlated situations created by the Mott metal-insulator transitions, modeled by linear chains, rings, or cubic lattices of the equally spaced hydrogen atoms, and the π-electron networks described by the Hubbard and Pariser-Parr-Pople Hamiltonians that model one-dimensional metallic systems with periodic boundary conditions. However, typical ACP methods neglect connected triply excited T3 clusters, which are required to produce quantitative results in most chemical applications. Previous attempts to incorporate these clusters using many-body perturbation theory arguments within the ACP framework have only been partly successful. In this dissertation, we address this concern by employing the active-space ideas to incorporate the dominant T3 amplitudes in the ACP methods in a robust, yet computationally affordable, manner. Furthermore, taking into consideration that the various diagram modifications defining ACP approaches were derived using minimum-basis-set models, we introduce a novel ACP scheme utilizing basis-set-dependent scaling factors, denoted as ACCSD(1,3 × no/(no + nu) + 4 × nu/(no + nu)), to extend the ACP methodologies to larger basis sets.In the second part of this dissertation, we discuss a novel approach to extrapolating the exact energetics out of the early stages of full configuration interaction quantum Monte Carlo (FCIQMC) propagations, even in the presence of strong correlations, by merging the ACP approaches with the recently proposed cluster-analysis-driven FCIQMC (CAD-FCIQMC) methodology. In the spirit of externally corrected CC approaches, in the CAD-FCIQMC methodology, one solves CCSD-like equations for the one- and two-body clusters in the presence of their three- and four-body counterparts extracted from the FCIQMC stochastic wavefunction sampling. In this dissertation, we extend CAD-FCIQMC to the strong correlation regime by repartitioning the CC equations so that selected coupled-pair contributions are extracted from FCIQMC as well. For each new methodology described in this thesis, we discuss the relevant mathematical and computer implementation details and provide numerical examples illustrating its performance in challenging strongly correlated situations.
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Title: QUANTIFYING, MONITORING, AND MANAGING BIODIVERSITY ACROSS MULTIPLE SPATIAL SCALES
Creator: Wright, Alexander D.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: This dissertation aims to investigate how science can effectively inform management and policy decisions, leading to positive conservation outcomes for vulnerable wildlife communities. Successful conservation requires the incorporation of ecological uncertainty and socio-ecological complexity into the decision-making process. To navigate the uncertainty and complexity pertinent to landscape conservation, I demonstrate a multi-scaled approach to quantify, monitor, and manage amphibians in a...
Show moreThis dissertation aims to investigate how science can effectively inform management and policy decisions, leading to positive conservation outcomes for vulnerable wildlife communities. Successful conservation requires the incorporation of ecological uncertainty and socio-ecological complexity into the decision-making process. To navigate the uncertainty and complexity pertinent to landscape conservation, I demonstrate a multi-scaled approach to quantify, monitor, and manage amphibians in a case study of a regional network of national parks. In Chapter 1, I quantify biodiversity across multiple spatial scales by fitting a multi-region community occupancy model to regional amphibian monitoring data to elucidate the drivers and threats(s) to biodiversity and the relevant scale(s) to target management. In Chapter 2, I explore the efficacy of different monitoring programs and identify strategies to monitor biodiversity across multiple spatial scales to minimize uncertainty in system dynamics. In Chapter 3, I predict the impacts of, and then spatially prioritize, management to increase biodiversity across multiple spatial scales by incorporating governance complexity in the decision-making process. In Chapter 4, I synthesize findings from previously published studies to determine the extent, and conditions under which, decision support frameworks can lead to positive conservation outcomes. The chapters of this dissertation provide critical guidance on how to scale up conservation science to match the scope and scale of the ecological systems and governance structures it is meant to inform. The application of this knowledge can help conservation scientists, managers, and policy makers address the complex and multi-scaled biodiversity crisis.
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Title: Towards a Robust Unconstrained Face Recognition Pipeline with Deep Neural Networks
Creator: Shi, Yichun
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Face recognition is a classic problem in the field of computer vision and pattern recognition due to its wide applications in real-world problems such as access control, identity verification, physical security, surveillance, etc. Recent progress in deep learning techniques and the access to large-scale face databases has lead to a significant improvement of face recognition accuracy under constrained and semi-constrained scenarios. Deep neural networks are shown to surpass human performance...
Show moreFace recognition is a classic problem in the field of computer vision and pattern recognition due to its wide applications in real-world problems such as access control, identity verification, physical security, surveillance, etc. Recent progress in deep learning techniques and the access to large-scale face databases has lead to a significant improvement of face recognition accuracy under constrained and semi-constrained scenarios. Deep neural networks are shown to surpass human performance on Labeled Face in the Wild (LFW), which consists of celebrity photos captured in the wild. However, in many applications, e.g. surveillance videos, where we cannot assume that the presented face is under controlled variations, the performance of current DNN-based methods drop significantly. The main challenges in such an unconstrained face recognition problem include, but are not limited to: lack of labeled data, robust face normalization, discriminative representation learning and the ambiguity of facial features caused by information loss.In this thesis, we propose a set of methods that attempt to address the above challenges in unconstrained face recognition systems. Starting from a classic deep face recognition pipeline, we review how each step in this pipeline could fail on low-quality uncontrolled input faces, what kind of solutions have been studied before, and then introduce our proposed methods. The various methods proposed in this thesis are independent but compatible with each other. Experiment on several challenging benchmarks, e.g. IJB-C and IJB-S show that the proposed methods are able to improve the robustness and reliability of deep unconstrained face recognition systems. Our solution achieves state-of-the-art performance, i.e. 95.0\% TAR@FAR=0.001\% on IJB-C dataset and 61.98\% Rank1 retrieval rate on the surveillance-to-booking protocol of IJB-S dataset.
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Title: Heterogeneous Thalamic Reticular Nucleus Neurons and Their Functional Role in Thalamocortical Processing
Creator: Harding-Jackson, Laura
Date: 2021
Collection: Electronic Theses & Dissertations
Description: The thalamic reticular nucleus (TRN) is an integral regulator of information flow between the thalamus and cortex. The TRN receives synaptic inputs from both cortical and thalamic regions and based upon this information it selectively inhibits thalamic activity. TRN neurons produce action potentials in two distinct modes: a fast, transient burst discharge from a hyperpolarized state, and a prolonged, tonic discharge from a relatively depolarized state. While previous studies have...
Show moreThe thalamic reticular nucleus (TRN) is an integral regulator of information flow between the thalamus and cortex. The TRN receives synaptic inputs from both cortical and thalamic regions and based upon this information it selectively inhibits thalamic activity. TRN neurons produce action potentials in two distinct modes: a fast, transient burst discharge from a hyperpolarized state, and a prolonged, tonic discharge from a relatively depolarized state. While previous studies have characterized burst discharge as a transient high frequency discharge (> 250 Hz), these electrophysiological studies reveal a highly variable range of burst frequencies (4- 342 Hz). In these studies, I aim to discover the mechanisms underlying these highly variable burst frequencies, as well as their functional role in thalamocortical processing.In chapter two, I found that bursts from TRN neurons with relatively higher frequency discharge (>100 Hz) contain more action potentials per burst. These neurons also have higher input resistances, broader action potentials, higher action potential thresholds, and larger somas. The amplitude of the T-type calcium channel-mediated low-threshold spike, which underlies the burst discharge, is positively correlated with both the burst discharge frequency and the number of action potentials per burst. I next investigated whether small conductance calcium-activated potassium channels (SK channels) could mediate the differences in burst firing rate and action potential number. Blocking SK channels increased the frequency and duration of the burst but did not increase the amplitude of the underlying T-type calcium current. Prior studies suggest that T-type calcium channels are distributed along the dendrites in TRN neurons with high frequency burst discharge. In chapter three, I examine the distribution of dendritic calcium activity within the lower frequency bursting neurons. While the calcium signal was lower in these neurons all along the dendrites, the calcium signal was evenly distributed across proximal, intermediate, and distal dendritic regions. Investigation of SK channel activity revealed significant location-specific effects. In lower frequency bursting neurons, SK channels had the greatest influence at proximal and distal locations. In higher frequency bursting neurons, SK channels had the greatest influence at proximal and intermediate dendritic locations. Heterogeneous TRN burst discharge frequencies may represent a diverse cell population with unique dendritic ion channel composition and distribution. These results may improve our understanding of the mechanisms of TRN neuron afferent synaptic integration as well as modulation of thalamocortical inhibition. In chapter four I investigate whether intrinsic properties of TRN neurons are altered in the Fmr1-KO mouse model of Fragile X Syndrome (FXS). Individuals with FXS experience a variety of comorbidities that could involve TRN function, such as altered sensory perceptions, sleep disorders, and epilepsy. Analysis of intrinsic cellular properties revealed no differences in TRN neuron properties. Further investigation of synaptic plasticity, which is an abnormal finding in several other brain regions in FXS, also revealed no pathology. These findings suggest that TRN dysfunction does not contribute to FXS pathology.
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Title: Environments Effect on Mood : A Comparative Analysis of Environments on Mood Enhancement
Creator: Hayes, Jonah
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Mental health is an issue that millions of people are suffering and struggling with, reconnecting with natural environments could be part of the solution to this problem. Although research demonstrated the significance of the healing properties of natural environments, little research compared natural environments to each other. This research explores which aspects of different natural environments have a positive impact on mood. Using survey questionnaires, two environments were tested. The...
Show moreMental health is an issue that millions of people are suffering and struggling with, reconnecting with natural environments could be part of the solution to this problem. Although research demonstrated the significance of the healing properties of natural environments, little research compared natural environments to each other. This research explores which aspects of different natural environments have a positive impact on mood. Using survey questionnaires, two environments were tested. The first being natural environments, where participant exposure to man-made or urban elements is limited and they are surrounded by natural elements. The second environment, urban environments, are spaces such as parks that are not separated from the urban environment. While in the urban environments’ participants were still able to perceive the urban elements that surrounds the space, such as cars, buildings, and roads. Participants were surveyed before and after using the spaces to allow the measuring and analysis of the change the participants experienced. Both the change in mental restoration, but also of the perceived variables of the space. Statistical analysis of the survey responses showed that a greater amount of change to the perceived variables, and mental restoration happened in natural environments, but both environments were restorative. This supports the idea that accessibility to a diverse set of environments and recreational elements will increase mental restoration. Therefore, policy practitioners, and designers should work to increase park space accessibility to a diverse set of environments and recreation amenities.
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Title: EPIDEMIC MODELS UNDER MOBILITY ON MULTI-LAYER NETWORKS
Creator: Abhishek, Vishal
Date: 2021
Collection: Electronic Theses & Dissertations
Description: We study epidemic spreading models namely, SIS and SIR models, under mobility on multilayer networks. In particular, we consider a patchy environment in which each patch comprises individuals belonging the different classes, e.g., individuals in different socio-economic strata. We model the mobility of individuals of each class across different patches through an associated Continuous Time Markov Chain (CTMC). The topology of these multiple CTMCs constitute the multi-layer network of mobility...
Show moreWe study epidemic spreading models namely, SIS and SIR models, under mobility on multilayer networks. In particular, we consider a patchy environment in which each patch comprises individuals belonging the different classes, e.g., individuals in different socio-economic strata. We model the mobility of individuals of each class across different patches through an associated Continuous Time Markov Chain (CTMC). The topology of these multiple CTMCs constitute the multi-layer network of mobility. At each time, individuals in the multi-layer network of spatially-distributed patches move according to their CTMC and subsequently interact with the local individuals in the patch according to SIS or SIR models. We establish the existence of various equilibria under different parameter regimes and establish their (almost) global asymptotic stability using Lyapunov techniques. We also derive simple conditions that highlight the influence of the multi layer network on the stability of these equilibria. We numerically illustrate that the derived model provides a good approximation to the stochastic model with a finite population and also demonstrate the influence of the multi-layer network structure.Next, we extend some of the results to the case of weakly connected networks. Here, we use the notion of strongly connected components and input to state stability to study the stability of equilibria. Finally, we consider a resource allocation problem to maximize the rate of convergence to an equilibrium. We show that under certain assumptions the problem can be formulated as a geometric program. We provide numerical illustrations to corroborate the results.
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Title: ROBUST HYSTERESIS COMPENSATION FOR NANOPOSITIONING CONTROL
Creator: Al-Nadawi, Yasir Khudhair
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Piezoelectric and other smart material-based actuators are widely used in micro- and nano positioning applications. However, the intrinsic hysteretic behavior of these actuators deteriorates their tracking performance. This dissertation, composed of three parts, is focused on nonlinear control methods for compensating the hysteresis and achieving high-precision control in the presence of model uncertainties. An inversion-based adaptive conditional servocompensator (ACS) is first proposed,...
Show morePiezoelectric and other smart material-based actuators are widely used in micro- and nano positioning applications. However, the intrinsic hysteretic behavior of these actuators deteriorates their tracking performance. This dissertation, composed of three parts, is focused on nonlinear control methods for compensating the hysteresis and achieving high-precision control in the presence of model uncertainties. An inversion-based adaptive conditional servocompensator (ACS) is first proposed, where a nanopositioning system represented as a linear system preceded with a hysteresis nonlinearity modeled with a Modified Prandtl-Ishlinskii (MPI) operator. With an approximate inverse MPI operator as a compensator, the resulting system takes a semi-affine form. The proposed controller consists of two parts, a continuously-implemented sliding mode control (SMC) law followed by an ASC. The hysteresis inversion error is treated as a matched disturbance and its analytical bound is used to minimize the conservativeness of the SMC design. Under mild assumptions, the well-posedness and periodic stability of the closed-loop system are established. The second part of the dissertation focuses on designing an inversion-free ACS to achieve precise tracking control of systems with hysteresis, without requiring explicit inversion of the hysteresis. To facilitate the control design, the MPI operator is rearranged into a form comprised of three parts: a linear term, a nominal hysteretic term represented by a classical Prandtl-Ishlinskii (PI) operator, and a hysteretic perturbation. The bound on the hysteretic perturbation is further derived based on the parameter uncertainty of the MPI operator. To properly ``cancel'' the nominal hysteresis effect without inversion, a technique involving a low-pass filter is introduced. It is shown that, with persistent excitation, the closed-loop variables are ultimately bounded and the tracking error approaches a neighborhood of zero, where the neighborhood can be made arbitrarily small via the choice of the SMC boundary layer width parameter and the servocompensator order. In the third part, an output feedback-based hysteresis compensation approach is used using dynamic inversion and extended high-gain observers. With mild assumptions on the properties of the hysteresis nonlinearity, the system can be represented as an uncertain, non-affine, nonlinear system containing a hysteretic perturbation. Dynamic inversion is used to deal with the non-affine input, uncertainties, and the hysteretic perturbation, where the latter two are estimated using an extended high-gain observer. Analysis of the closed-loop system under output feedback shows that the tracking error converges to a small neighborhood near the origin, which can be made arbitrarily small via proper choice of time-scale parameters of dynamic inversion and the observer, respectively. The efficacy of the three proposed controllers is verified experimentally on a commercial nanopositioning device under different types of periodic reference inputs, via comparison with multiple inversion-based and inversion-free approaches.
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Title: Forgotten Families of the Sea and the Sun : An ethnography of autism in Puerto Rico
Creator: Anderson-Chavarria, Melissa
Date: 2021
Collection: Electronic Theses & Dissertations
Description: In biomedical terms, Autism Spectrum Disorder (ASD) is considered a neurodevelopmental disorder impacting several core areas of an individual’s development including the socio-communicative, the behavioral, and the sensory. A broader conceptualization of autism has emerged, spurred in large part by the contemporary Neurodiversity Movement, expanding our considerations of autism beyond the biomedical towards an understanding of autism as a lived, neurodiverse social phenomenon. However,...
Show moreIn biomedical terms, Autism Spectrum Disorder (ASD) is considered a neurodevelopmental disorder impacting several core areas of an individual’s development including the socio-communicative, the behavioral, and the sensory. A broader conceptualization of autism has emerged, spurred in large part by the contemporary Neurodiversity Movement, expanding our considerations of autism beyond the biomedical towards an understanding of autism as a lived, neurodiverse social phenomenon. However, despite this conceptual expansion, the current autism literature continues to be disproportionately dominated by the small subset of autistic lived experiences of majority White North American and European autistic individuals and families living in high-income, resource-rich settings. Therefore, there is a need for a diversification of autism studies to include experiences of minority/marginalized autistic individuals and autism families living in relatively low-income, resource-deficit areas. This dissertation contributes towards addressing this gap in the literature by focusing on the perspectives and experiences of Puerto Rican autism families attempting to navigate the island nation’s challenging medical and educational infrastructure to access scarce, but much-needed resources and services for their autistic children. This dissertation presents findings from ethnographic research conducted from 2017 to 2019 examining the autism community of Puerto Rico. Data collection consisted of over 350 hours of participant-observation conducted at autism-related settings such as health care facilities, educational institutions, non-profit organizations, and autism family homes; and 73 semi-structured interviews (67 primary, 6 follow-up) were conducted between two cohorts: 1) parents of autistic children (n=35) and 2) autism treatment/care providers (n=32). Analysis of this data sheds light on various aspects of the Puerto Rican autism family experience, including conceptualizations of autism, theories of causation and their impact on parental vaccination decision-making, language practices and ideologies, and family resource navigation. By exploring each of these individual aspects, this study elucidates how the holistic experience of the Puerto Rican autism family extends far beyond strictly biomedical delineations of an autism diagnosis. Rather, this dissertation argues that the lived reality of the autism family experience is fundamentally informed by the historical, politico-economic, sociocultural, and structural contexts in which it is lived. Furthermore, this study demonstrates the importance of including a diversity of autism family experiences, especially those in low-income, resource-deficit settings, within the autism literature. It is hoped that this will lead to the development of appropriate autism screening, diagnostic, treatment/interventional, and family support protocols that are applicable and accessible not only to those autism families that have the most access and representation, but also to those who may have the least.
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Title: Diagrammatic and Geometric Invariants of Hyperbolic Weakly Generalized Alternating Knots
Creator: Bavier, Brandon
Date: 2021
Collection: Electronic Theses & Dissertations
Description: We study the relationship between knot and link diagrams on surfaces and their invariants coming from hyperbolic geometry. A \indef{link diagram on a surface}, denoted $\pi(L)\subset F$, is a way of projecting a link $L$ in some manifold $M$ onto some surface $F\subset M$. This generalizes the notion of a link diagram, and has been studied with a variety of conditions. We will work with the weakly generalized alternating knots and links of Howie and Purcell, which gives certain criteria to...
Show moreWe study the relationship between knot and link diagrams on surfaces and their invariants coming from hyperbolic geometry. A \indef{link diagram on a surface}, denoted $\pi(L)\subset F$, is a way of projecting a link $L$ in some manifold $M$ onto some surface $F\subset M$. This generalizes the notion of a link diagram, and has been studied with a variety of conditions. We will work with the weakly generalized alternating knots and links of Howie and Purcell, which gives certain criteria to ensure the diagram is interesting. A cusp of a hyperbolic knot $K$ is a neighborhood of $K$ in $M\setminus K$, and the cusp volume is the Euclidean volume of a maximal cusp. We show that the cusp volume of a weakly generalized alternating knot, with some additional conditions, is bounded both above and below based on the twist number of $\pi(K)$ and $\chi(F)$. This is done by constructing a new essential surface for $K$ that has nice properties, including having Euler characteristic based on the twist number as opposed to the crossing number. Our bound on cusp volume leads to interesting bounds on other geometric properties of $K$, including slope length and volumes of Dehn surgery. The volume}of a hyperbolic link $L$ in a manifold $M$ is the hyperbolic volume of the complement $M\setminus L$. We can show that volume is also bounded below by the twist number of $\pi(L)$ and $\chi(F)$. We do this by generalizing the Jones polynomial to weakly generalized alternating links, and showing that there is a relation between this polynomial and the twist number, and this polynomial and the volume. Through the course of proving this bound, we also get relations between the guts of the checkerboard surfaces of $L$ and this generalized Jones polynomial. In addition, if we are working inside a thickened surface, the twist number becomes an isotopy invariant of $L$.
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Title: Keeping the Tradition Alive : Irish Traditional Music Sessions During COVID-19
Creator: Bobker, Andrew
Date: 2021
Collection: Electronic Theses & Dissertations
Description: In the spring of 2020, performers of traditional Irish music responded to pandemicinducedsocial distancing by creating a new variant of an old tradition: the virtual Irish session. Unlike conventional pub sessions, virtual sessions occur entirely in virtual space, facilitated by conferencing applications like Zoom or YouTube livestreaming. The move to virtual sessions presents numerous challenges to the traditional structure and norms of Irish traditional music. This thesis will explore the...
Show moreIn the spring of 2020, performers of traditional Irish music responded to pandemicinducedsocial distancing by creating a new variant of an old tradition: the virtual Irish session. Unlike conventional pub sessions, virtual sessions occur entirely in virtual space, facilitated by conferencing applications like Zoom or YouTube livestreaming. The move to virtual sessions presents numerous challenges to the traditional structure and norms of Irish traditional music. This thesis will explore the strategies and motivations of Irish musicians as they have adapted to the conditions of COVID-19 and isolation. Maintaining an authentic practice within the auspices of technological innovation involves the negotiation of geography, ethnicity, and selective tradition in a complex social space. This work is based in large part on ethnographic research conducted between March and December of 2020, including both in-person interviews and Internet ethnography. Interviews were conducted with musicians in Austin, Texas; Portland, Maine; Seattle, Washington; and Boston, Massachusetts.
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