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Title: Weighting in multilevel models
Creator: Tong, Bing
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Large-scale survey programs usually use complex sampling designs such as unequal probabilities of selection, stratifications, and/or clustering to collect data to save time and money. This leads to the necessity to incorporate sampling weights into multilevel models in order to obtain accurate estimates and valid inferences. However, the weighted multilevel estimators have been lately developed and minimal guidance is left on how to use sampling weights in multilevel models and which...
Show moreLarge-scale survey programs usually use complex sampling designs such as unequal probabilities of selection, stratifications, and/or clustering to collect data to save time and money. This leads to the necessity to incorporate sampling weights into multilevel models in order to obtain accurate estimates and valid inferences. However, the weighted multilevel estimators have been lately developed and minimal guidance is left on how to use sampling weights in multilevel models and which estimator is most appropriate.The goal of this study is to examine the performance of multilevel pseudo maximum likelihood (MPML) estimation methods using different scaling techniques under the informative and non-informative condition in the context of a two-stage sampling design with unequal probabilities of selection. Monte Carlo simulation methods are used to evaluate the impact of three factors, including informativeness of the sampling design, intraclass correlation coefficient (ICC), and estimation methods. Simulation results indicate that including sampling weights in the model still produce biased estimates for the school-level variance. In general, the weighted methods outperform the unweighted method in estimating intercept and student-level variance while the unweighted method outperforms the weighted methods for school-level variance estimation in the informative condition. In general, the cluster scaling estimation method is recommended in the informative sampling design. Under the non-informative condition, the unweighted method can be considered a better choice than the weighted methods for all the parameter estimates. Besides, the ICC has obvious effects on school-level variance estimates in the informative condition, but in the noninformative condition, it also affects intercept estimates. An empirical study is included to illustrate the model.
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Title: I. amhb : (anti)aromaticity-modulated hydrogen bonding. ii. evaluation of implicit solvation models for predicting hydrogen bond free energies
Creator: Kakeshpour, Tayeb
Date: 2019
Collection: Electronic Theses & Dissertations
Description: My doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In...
Show moreMy doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In the second chapter, I used accurately measured hydrogen bond energies for a range of substrates and solvents to evaluate the performance of implicit solvation models in combination with density functional methods for predicting solution phase hydrogen bond energies. This benchmark study provides useful guidelines for a priori modeling of hydrogen bonding-based designs.Coordinates of the optimized geometries and crystal structures are provided as supplementary materials.
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Title: Foundation and growth of the Cuban-based transatlantic slave trade, 1790-1820
Creator: Felipe Gonzalez, Jorge
Date: 2019
Collection: Electronic Theses & Dissertations
Description: This dissertation discusses the creation and expansion of the Cuban-based transatlantic slave trading infrastructure at the turn of the nineteenth century. Since the beginning of the conquest of the Americas, foreigners such as the Portuguese, Dutch, British, and Americans controlled the provision of captives to the Spanish colonies under a Spanish state-controlled system known as Asientos. Such dependency was challenged in the 1790s when a combination of international events, favorable...
Show moreThis dissertation discusses the creation and expansion of the Cuban-based transatlantic slave trading infrastructure at the turn of the nineteenth century. Since the beginning of the conquest of the Americas, foreigners such as the Portuguese, Dutch, British, and Americans controlled the provision of captives to the Spanish colonies under a Spanish state-controlled system known as Asientos. Such dependency was challenged in the 1790s when a combination of international events, favorable colonial legislation, and a restructuring of the colonial economy turned Cuba into an expanding sugar plantation economy based on African forced labor. By the 1820s, in just three decades, Cuban merchants had effectively overcome that external dependency by setting up the conditions for trading slaves on the African coast. This thesis argues that foreign slavers trading in the island since the 1790s were pivotal in training the first generation of Cuban slave ship captains, providing a slave merchant fleet to Cubans, and introducing Cuban merchants to African slave trading networks. In order to illustrate the establishment of Cuban operations in Africa, this dissertation focuses on the creation of a slave-trading corridor between Havana and Rio Pongo, Guinea-Conakry. Cuban merchants, I argue, reached the region known as Rio Pongo as a result of the U.S. slave traders who moved their operations to Cuba after 1808. The expansion of the slave trade in Rio Pongo to supply the expanding Cuban demand had also an impact on that coastal African society.
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Title: Multi-scale approaches to global challenges in a telecoupled world
Creator: Xu, Zhenci
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Global challenges such as water crisis, energy insecurity, biodiversity loss, land use change and climate change pose threats to the world's sustainability. Globalization enhances the connection of distant areas through various environmental and socioeconomic interactions. To solve the increasing challenges of achieving global sustainability in the context of globalization, the new telecoupling framework (socioeconomic and environmental interactions over distances) is proposed (Liu et al....
Show moreGlobal challenges such as water crisis, energy insecurity, biodiversity loss, land use change and climate change pose threats to the world's sustainability. Globalization enhances the connection of distant areas through various environmental and socioeconomic interactions. To solve the increasing challenges of achieving global sustainability in the context of globalization, the new telecoupling framework (socioeconomic and environmental interactions over distances) is proposed (Liu et al. 2013). A growing body of research has been exploring the dynamics, impacts, mechanisms, and structure of distant interactions involving global challenges. However, based on the telecoupling framework, we find no research that studies the evolution of multiple global environmental and socioeconomic interaction networks together. Also, the interactions between two kinds of distant virtual resource transfers simultaneously and the drivers of virtual resource transfers at the national scale are still unknown. Little research explores the evolution of virtual resource transfers at a national scale. The impacts of distant interactions on sending systems' sustainability at the regional scale has rarely been quantified and systematically analyzed. To address these knowledge gaps, I did the following work: First, I assessed the evolution of global telecouplings such as water, energy, land, CO2 emission, nitrogen emission and financial capital transfer networks and discussed how they have impacts on global water scarcity, energy crisis, land use change, global warming and nitrogen pollution. Second, I evaluated the interactions across two kinds of national telecouplings (interregional water and energy networks), and discussed their implications for the trading region's water scarcity and energy security, and explore the drivers of national telecouplings. Third, I studied the evolution of national virtual energy network. Fourth, I explored the water and food sustainability in a sending system of telecoupling (food transfer aimed at ensuring food security in the receiving system) at the regional scale. These four works have been accomplished in four chapters, respectively.Main findings from this dissertation include: At the global scale, the volumes of all these flows, except for land flow, increased over time. Financial capital flows increased most (188.9%), followed by flows of CO2 (59.3%), energy (58.1%), water (50.7%) and nitrogen (10.5%), while land transfer decreased by 8.8%. At the national scale using China as a demonstration, 40% of provinces gained one kind of resource (either water or energy) through trade at the expense of losing the other kind of internal resource (energy or water), and 20% of provinces suffered a double loss of both water and energy. The remaining provinces gained both water and energy. Over time, the total virtual energy transferred from energy-scarce to energy-abundant provinces increased from 43.2% to 47.5% from 2007 to 2012. At a regional scale, irrigated agriculture's annual water footprint in the North China Plain increased from 53 billion m3 in 1986 to 78 billion m3 in 2010. All counties faced unsustainable water use - local water consumption was greater than local renewable freshwater - even as the average crop water productivity increased from 0.90 kg.m-3 to 1.94 kg.m-3. These findings provide useful information for policy making to address environmental and socioeconomic challenges and build distant cooperation across multiple scales.
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Title: Connecting reflection and practice : transforming a mathematics classroom culture of participation
Creator: Martinez Hinestroza, Jose Manuel
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Unlike previous research on participation in mathematics classrooms that focuses on the teacher's role eliciting student talk, the purpose of this dissertation is to study the interactive process through which a teacher connected her reflection and practice, fostering transformations in the culture of participation in a third-grade Spanish immersion mathematics classroom. I draw on hermeneutic listening (Davis, 1996) to understand the teacher's departure from listening for predetermined ways...
Show moreUnlike previous research on participation in mathematics classrooms that focuses on the teacher's role eliciting student talk, the purpose of this dissertation is to study the interactive process through which a teacher connected her reflection and practice, fostering transformations in the culture of participation in a third-grade Spanish immersion mathematics classroom. I draw on hermeneutic listening (Davis, 1996) to understand the teacher's departure from listening for predetermined ways of participating. Methods from participatory design research with children (Bang & Vossoughi, 2016; Groundwater-Smith et al., 2014) and analytical tools from social semiotics (van Leeuwen, 2005) informed the collaborative design and analysis of interventions intended to promote a more inclusive culture of participation. Findings indicate that bringing the students' and the teachers' perspectives on participation into dialogue helped the teacher broaden her ideas on participation. A prolonged, iterative process was necessary to connect these reflections to a practice where the teacher learned to listen hermeneutically for participation. This process started with teacher-researcher co-designed interventions and continued as the teacher recognized participation in unexpected places and moments. The culture of participation evolved toward embracing multiple ways of participating in cooperative mathematical activity in which the students and the teacher addressed unanticipated ideas that emerged in interactions. I describe the semiotic innovations that characterized these transformations and the contextual influences that mediated semiotic innovation. I discuss implications for mathematics educatioSn research and teacher professional development.
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Title: Determinants of eating behaviors of us army ROTC cadets in Midwestern universities
Creator: George, Beatriz G.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Young adults 18-25 years of age, the largest demographic of the military, experience a high burden of obesity and eating disorders (ED) despite an emphasis on physical fitness, body composition, and operational readiness. Etiologic models for obesity and ED suggest body dissatisfaction (BD), dieting, negative affect (NA), and affect regulation represent potentially shared pathways. However, no studies have examined these factors and their shared pathways in military personnel, including ROTC...
Show moreYoung adults 18-25 years of age, the largest demographic of the military, experience a high burden of obesity and eating disorders (ED) despite an emphasis on physical fitness, body composition, and operational readiness. Etiologic models for obesity and ED suggest body dissatisfaction (BD), dieting, negative affect (NA), and affect regulation represent potentially shared pathways. However, no studies have examined these factors and their shared pathways in military personnel, including ROTC cadets. The overarching aim of this dissertation research was to investigate if ED symptoms were associated with body mass index (BMI), an indicator of obesity, and to describe potential correlates of their development. Three specific aims of this research focus on: 1) the prevalence and correlates of ED risk classification and symptoms in ROTC cadets, 2) the association between ED symptoms and BMI, and their potentially shared mechanisms, psychological inflexibility related to BD and dieting, and 3) the gaps in knowledge about eating behaviors and mediators of eating behaviors within the ROTC context and from perspective of ROTC cadets.In 2018, US Army ROTC cadets (n = 205) were recruited from two Midwestern universities and completed questionnaires about demographics, military-specific eating behaviors and mediators of eating behaviors, ED symptoms, and anthropometric measures. Chi-square, multivariable logistic regression, and multiple linear regression were performed in determining the rate of ED risk classification and correlates of ED risk classification and symptoms (Aim 1). Two measures of psychological inflexibility related to BD and dieting, in addition to the data for Aim 1, were used in mediation path analysis to examine the association of ED symptoms to BMI, and the indirect effects as mediated by psychological inflexibility related to BD and dieting (Aim 2). A purposively selected sample of eighteen cadets participated in one-on-one, semi-structured telephone interviews on eating behaviors and their mediators in the context of ROTC (Aim 3). Interviews were analyzed using thematic analysis to identify the most important themes and determinants related to eating behaviors in ROTC cadets.We found that ED symptoms and ED risk classification are prevalent in a sample of US Army ROTC cadets (10.1% of sample). Correlates associated with greater likelihood of ED risk classification and elevated ED symptoms were: sex, dieting, and military contextual factors such as attempting dieting and weight loss to meet body composition standards, and peers' comments on weight. Total ED symptoms scores were positively associated with BMI and partially mediated by psychological inflexibility related to BD and dieting. Cadets discussed perceived determinants of eating behaviors which included traditional determinants (e.g. time, money, nutrition knowledge) and ROTC-context specific determinants (e.g. preparation for body composition assessments and body image perceptions), which contributed to unhealthy weight control behaviors (dieting) and negative body image perceptions (BD) for some cadets. In conclusion, the prevalent correlates for eating disorder symptoms and risk in the sample of US Army ROTC cadets in this study were factors related to the enforcement of body composition standards and body image perceptions in the military context which may contribute to the development of dieting, BD, and NA. Longitudinal and/or intervention studies on this important topic may benefit our understanding of how ED symptoms and obesity develop over time and how targeting dieting, BD, NA, and affect regulation may be leveraged to mitigate ED and obesity to promote physical fitness, operational readiness and health in military personnel.
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Title: Optogenetic analysis of excitatory and inhibitory neurotransmission in the enteric nervous system
Creator: Perez-Medina, Alberto L.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: The enteric nervous system (ENS) is embedded within the gastrointestinal (GI) tract and controls GI function. Impaired ENS function leads to altered patterns of motility and secretion, causing GI disease. For instance, functional gastrointestinal disorders (FGID) are caused by poorly understood alterations in the structure and function of nerves, smooth muscle cells (SMC), and other cell types in the GI tract. It is estimated that these disorders comprise about 41% of the total GI...
Show moreThe enteric nervous system (ENS) is embedded within the gastrointestinal (GI) tract and controls GI function. Impaired ENS function leads to altered patterns of motility and secretion, causing GI disease. For instance, functional gastrointestinal disorders (FGID) are caused by poorly understood alterations in the structure and function of nerves, smooth muscle cells (SMC), and other cell types in the GI tract. It is estimated that these disorders comprise about 41% of the total GI complications in the United States. Also, altered patterns of motility that occur in the GI muscles is a hallmark characteristic of FGIDs. Although the ENS is fairly understood, further elucidation of the enteric circuitry that governs GI motility would help to understand the pathophysiology of FGID. For that reason, identifying the contributions of classes of enteric neurons that control GI motility and secretion could aid in the identification of novel therapeutic targets for the treatment of FGIDs. A widely used method to study neural control of GI motility is sharp-electrode electrophysiological recordings from the smooth muscle or enteric neurons. Conventional, intracellular electrophysiological recordings have relied on electrical stimulation of enteric neurons which will activate all neurons in an ex vivo preparation of the ENS, and does not allow cell-specific activation of individual subpopulations of myenteric neurons. To overcome this problem, we used immunohistochemical methods to identify subpopulations of myenteric neurons and the optogenetically activated protein channelrhodopsin-2 (ChR2) that can be selectively expressed in subsets of enteric neurons. In Chapter 3, immunohistochemical studies of the mouse enteric nervous system are performed using the purinergic neuronal marker, vesicular nucleotide transporter (VNUT) along with markers for specific subsets of myenteric neurons and nerve fibers (e.g., neuronal nitric oxide synthase, choline acetyltransferase, calretinin, calbindin, and tyrosine hydroxylase),. Chapter 4 compares electrical and optogenetic electrophysiology recordings from myenteric neurons of mice that express ChR2 in nNOS neurons. The studies described in Chapter 5 use ChAT-ChR2-YFP-BAC transgenic mice which have eYFP tagged ChR2 expressed in cholinergic neurons. Optogenetics was used to isolate the cholinergic component of the ENS. The findings discussed in this dissertation provides evidence of a more sophisticated enteric circuitry of GI motility. (1) Purinergic neurons are likely a separate subpopulation of enteric neurons. VNUT is only expressed in the form of punctate varicosities at the nerve fibers and is not endogenously expressed in the soma of enteric neurons. VNUT also does not appear to colocalize with other neuronal immunoreactive markers within the myenteric plexus (mp), the tertiary plexus (tp), or circular smooth muscle layer of all tested tissue preps. (2) BLS of ChR2 expressed in nNOS neurons induced a purinergic/nitrergic biphasic IJP, suggesting that nNOS IMNs co-releases a purine as a neurotransmitter. Ectopic expression of ChR2 in non-nNOS neurons, however, could explain the biphasic IJP responses during electrophysiology recordings. Hence, the existence of separate subset populations of IMN populations (e.g., nNOS only and purinergic only IMNs) can't be ruled out. (3) BLS of ChR2 expressed in ChAT positive neurons induced EJPs and IJP responses. Inhibition of the nicotinic ACh receptor (nAChR) with mecamylamine significantly reduced the light-evoked IJP. Bath application of the purinergic P2Y1 antagonist, MRS 2179, was sufficient to abolish the IJP response, while the muscarinic ACh receptor antagonist, Scopolamine, abolished the EJP response. The data suggest that BLS of ChR2 activates cholinergic EMNs and cholinergic interneurons, and that activation of the cholinergic interneurons activates purinergic only IMNs that supply the smooth muscle, resulting in a predominant purinergic only IJP. Taken together, this work provides evidence for a diverse and more complex enteric neural circuit of GI motility. Future experiments should, however, focus on studying these enteric circuits at the level of the neuron, as these studies can provide a more in-depth analysis of the enteric circuitry.
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Title: Solidarity, safety, and online sovereignty : an inquiry into the social media sharing practices of indigenous and chicana women
Creator: Hutchinson, Leslie A.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: This dissertation contains a cultural, digital rhetorics inquiry into the social media sharing practices of Indigenous and Chicana women. Working alongside three women from her local community, I investigated how these women navigate concerns about online safety, intellectual property, and surveillance. To conduct my study, I integrated cultural rhetorics research methods into my research design, which informed how I collected data through hosting a talking circle and conducting follow-up...
Show moreThis dissertation contains a cultural, digital rhetorics inquiry into the social media sharing practices of Indigenous and Chicana women. Working alongside three women from her local community, I investigated how these women navigate concerns about online safety, intellectual property, and surveillance. To conduct my study, I integrated cultural rhetorics research methods into my research design, which informed how I collected data through hosting a talking circle and conducting follow-up interviews. Then, using grounded theory to analyze my data, I found that: 1) though these women experience various social oppressions within social media spaces, they find and create community to collectively act in resistance; and 2) the acts of resistance in which these women engage expand scholarly understandings of how social media platforms are designed to asymmetrically oppress users from marginalized backgrounds. Together, these findings dispel the myth that women-and particularly women of color-have had no stake in the development of online platforms. I argue, rather, that despite how these platforms are designed, women of color critically enact cultural sovereignty in online spaces through asserting their identities, fighting for political rights, and creating community in acts of not only resistance, but survivance.
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Title: Integrated remote sensing and crop system modeling for precision agriculture across spatial and temporal scales
Creator: Peter, Bradley George
Date: 2019
Collection: Electronic Theses & Dissertations
Description: In light of global environmental change, population pressure, and food production demands, there is considerable value in mapping biogeographic crop niche and characterizing crop productivity at multiple scales to enhance the impact of agricultural improvement across Africa. Crop system research has advanced sustainable strategies for intensifying food production; however, questions regarding where to implement innovative technologies are largely unresolved.This dissertation focuses on four...
Show moreIn light of global environmental change, population pressure, and food production demands, there is considerable value in mapping biogeographic crop niche and characterizing crop productivity at multiple scales to enhance the impact of agricultural improvement across Africa. Crop system research has advanced sustainable strategies for intensifying food production; however, questions regarding where to implement innovative technologies are largely unresolved.This dissertation focuses on four geographic questions: (1) Where is the fundamental climate niche of maize, pigeonpea, and sorghum across Africa? (2) Where are marginal lands in Malawi and what are the underlying drivers of marginality? (3) Based on the drivers of marginal maize production, what are geographic scaling options for integration of pigeonpea into maize-based cropping systems? (4) What spatial resolutions are effective for conducting precision agriculture at the farm scale in smallholder systems? Overarching themes within the geographic discipline such as the modifiable areal unit problem and ecological fallacy problem underpin this research. Marginal areas for maize are highlighted at the Africa and Malawi scales and overlain with the optimal climate niche for crops such as sorghum and pigeonpea that offer multiple ecosystem services (e.g., soil rehabilitation through nitrogen fixation). Crop productivity is evaluated at scales relative to policy making delineations in Malawi (i.e., country, district, and extension planning area) to disentangle heterogeneity at local scales that may appear homogeneous at broader scales. At the Malawi farm scale, this research included the use of a small unmanned aerial system (sUAS), national government satellites (e.g., Sentinel-2), and commercial satellites (e.g., SPOT 6). Spectral measurements of crop status were evaluated at multiple spatial resolutions (ranging from 0.07-20-m) to determine what spatial resolutions and what spectral indices are most effective for estimating crop yields and crop chlorophyll.Results of this research include high spatial resolution maps of maize, pigeonpea, and sorghum suitability across Africa, indicating that pigeonpea and sorghum occupy unique agroecological zones throughout the continent (e.g., sorghum in the Sahel region). Similarly, pigeonpea suitability in Malawi occupies a greater land area than the extent to which it is currently cultivated, demonstrating that integration into maize-based cropping systems, particularly where soil is marginal, can have beneficial scaling outcomes. For the smallholder farm scale, problems of clouds and satellite revisit rates have not yet been overcome for precision agriculture. In this regard, sUAS are a promising option for relating spectral signals to on-farm measurements of crop status. Evidence from drone flights conducted at two experimental farms in the central region of Malawi (Nyambi and Ntubwi) suggest that spatial resolutions closer to the plant scale (i.e., 14-27-cm) are most effective for relating spectral imagery to crop status. Moreover, the green normalized difference vegetation index (GNDVI) and green soil adjusted vegetation index (GSAVI) were consistently correlated with crop chlorophyll and yield, illustrating that a broad range of indices should be evaluated for precision agriculture.
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Title: The interaction between feature- and space-based attention
Creator: Ozsarfati, Gozde
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Although the separate effects of feature- and space-based attention are relatively well established, the conjoint effects of attending to both a location and a feature are under-investigated. I analyzed the literature and extracted three approaches that explain such conjoint effects, namely the independence, sensory gating, and boosting approaches. The three approaches have substantial supports and shortcomings, and the current study will investigate which of the three approaches provide the...
Show moreAlthough the separate effects of feature- and space-based attention are relatively well established, the conjoint effects of attending to both a location and a feature are under-investigated. I analyzed the literature and extracted three approaches that explain such conjoint effects, namely the independence, sensory gating, and boosting approaches. The three approaches have substantial supports and shortcomings, and the current study will investigate which of the three approaches provide the best prediction of behavioral performance. I conducted two experiments to investigate whether the interplay between feature- and space-based attention varied as a function of the elapsed time between the cue and the target onset. A space-feature combination cue directed attention to a target on which participants discriminated small changes in color saturation. Both the spatial and feature cues were partially valid, making it possible to assess the cueing effect. The time difference between the cue and the saturation change onsets was manipulated in fine steps. Experiment 1 showed that space- and feature-based attention had an interactive effect on performance, such that feature-based attention did not influence performance outside the focus of space-based attention regardless of the temporal asynchrony between the cue and target onset. Experiment 2 was conducted to determine which of the three approaches provided the best account for the interaction pattern by adding a spatially neutral condition. It showed that feature- and space-based attention influenced performance, yet feature-based attention could not influence the performance outside the focus of spatial attention regardless of the temporal asynchrony between the cue and target onset. Moreover, the effectiveness of feature-based attention was equivalent at the spatially valid and neutral locations. In conclusion, the findings resemble with the predictions of the sensory gating approach. While feature-based attention could operate at the attended location or under diffused spatial attention equally well, its effectiveness diminished outside the focus of spatial attention. Moreover, the spatial filter imposed on feature-based attention is more permeable than originally proposed by the sensory gating approach. Lastly, feature-based attention does not fully spread to an unattended location regardless of the time difference between the cue and target onsets.
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Title: DOWNLINK RESOURCE BLOCKS POSITIONING AND SCHEDULING IN LTE SYSTEMS EMPLOYING ADAPTIVE FRAMEWORKS
Creator: Abusaid, Osama M.
Date: 2018
Collection: Electronic Theses & Dissertations
Description: The present expansions in size and complexity of LTE networks is hindering their performance and their reliability. This hindrance is manifested in deteriorating performance in the User Equipment’s throughput and latency as a consequence to deteriorating the E-node B downlink throughput. This is leading to the need of smart E Node Base with various capabilities adapting to the changing communication environment. The proposed work aims at developing Self Organization (SO) techniques and...
Show moreThe present expansions in size and complexity of LTE networks is hindering their performance and their reliability. This hindrance is manifested in deteriorating performance in the User Equipment’s throughput and latency as a consequence to deteriorating the E-node B downlink throughput. This is leading to the need of smart E Node Base with various capabilities adapting to the changing communication environment. The proposed work aims at developing Self Organization (SO) techniques and frameworks for LTE networks at the Resource Blocks (RB) scheduling management level. After reviewing the existing literature on Self Organization techniques and scheduling strategies that have been recently implemented in other wireless networks, we identify several contrasting needs that can jointly be addressed. The deployment of the introduced algorithms in the communication network is expected to lead to improved and upgraded overall network performance. The main feature of the LTE networks family is the feed-back that the cell receives from the users. The feedback includes the down link channel assessment based on the User Equipment (UE) measure Channel Quality Indicator (CQI) in the last Transmission Time Interval (TTI). This feed-back should be the main decision factor in allocating Resource Blocks (RBs) among users. The challenge is how could one maps the users’ data onto the RBs based on the CQI. The Thesis advances two approaches towards that end:- the allocation among the current users for the next TTI should be mapped, consistent with historical feed-back CQI received from users over prior transmission durations. This approach also aims at offering a solution to the bottle-neck capacity issue in the scheduling of LTE networks. To that end, we present an implementation of a modified Self Organizing Map (SOM) algorithm for mapping incoming data into RBs. Such an implementation can handle the collective cell enabling our cell to become smarter. The criteria in measuring the E-node Base performance include throughput, fairness and the trade-off between these attributes.- Another promising and complementary approach is to tailor Recurrent Neural Networks (RNNs) to implement optimal dynamic mappings of the Resource Blocks (RBs) in response to the history sequence of the Channel Quality Indicator CQI feedback. RNNs can successfully build its own internal state over the entire training CQI sequence and consequently make the prediction more viable. With this dynamic mapping technique, the prediction will be more accurate to changing time-varying channel environments. Overall, the collective cell management would become more intelligent and would be adaptable to changing environments. Consequently, a significant performance improvement can be achieved at lower cost. Moreover, a general tunability of the scheduling system becomes possible which would incorporate a trade-off between system complexity and QoS.
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Title: The distribution and dynamics of resistance genes in soil microbiomes
Creator: Dunivin, Taylor Katherine
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "The soil microbiome harbors immense microbial biodiversity that encodes important functions of interest to public health. These include functional genes that encode resistance to antibiotics and arsenic. In the case of antibiotic resistance, transfer from environmental strains to pathogens is a public health risk, and arsenic resistance and metabolisms are important for bioremediation as they impact the fate of arsenic in the environment. While these resistance genes are well-characterized...
Show more"The soil microbiome harbors immense microbial biodiversity that encodes important functions of interest to public health. These include functional genes that encode resistance to antibiotics and arsenic. In the case of antibiotic resistance, transfer from environmental strains to pathogens is a public health risk, and arsenic resistance and metabolisms are important for bioremediation as they impact the fate of arsenic in the environment. While these resistance genes are well-characterized in vitro, the full scope of their environmental distribution, diversity, and interspecies transfer is unknown. A better understanding of the diversity and distribution of resistance genes would provide insights into the potential for mitigation of public health problems such as arsenic contamination and antibiotic resistance. The work in this dissertation used a combination of cultivation-dependent and -independent techniques to better understand the dynamics and distributions of antibiotic and arsenic resistance genes in the environment. The influence of a disturbance on microbial antibiotic resistance and arsenic related genes was investigated by examining soils overlaying an underground coal mine fire in Centralia, PA. Additionally, soil meta-analyses were used to determine broader distributions patterns of these genes. These data and methods not only provide insights into the distributions and dynamics of antibiotic resistance and arsenic related genes in soil microbiomes but also provide a framework for future studies of other functional genes."--Page ii.
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Title: The cultivation of haitian women's sense of selves : towards a field of action
Creator: Leger, Shewonda
Date: 2019
Collection: Electronic Theses & Dissertations
Description: This multimodal dissertation makes space for diasporic Haitian women's stories and lived experiences which continue to be under-theorized within rhetorical scholarship but are clearly significant within Haitian communities and rhetorical traditions. To bring awareness to Haitian women's lived experiences, in my dissertation, I present the findings of a study that addresses the ways diasporic Haitian women revisit and navigate memories through reflection to make sense of the ways their lived...
Show moreThis multimodal dissertation makes space for diasporic Haitian women's stories and lived experiences which continue to be under-theorized within rhetorical scholarship but are clearly significant within Haitian communities and rhetorical traditions. To bring awareness to Haitian women's lived experiences, in my dissertation, I present the findings of a study that addresses the ways diasporic Haitian women revisit and navigate memories through reflection to make sense of the ways their lived experiences contribute to different aspects of their identities. The two situations I used as catalysts for memory were---inhabiting and reflecting on practices and conversations of the Haitian kitchen space---and, looking at and revisiting photographs to understand how we, claim, (re)claim, and/or discover identities. To make this inquiry, I explored the act of reflection through in-depth interviews with three diasporic Haitian women. I aim to understand what new knowledge(s) do diasporic Haitian women recognize about their identities through the act of reflection and navigating memories? Further, I work towards understanding how do these new knowledges modify identity performances in the "now"? And, how does a sense of identity consciousness contribute to diasporic Haitian womens' experiences and practices moving forward? Overall, using modes, such as documentary and photography in my dissertation, I make space for diasporic Haitian women's voices in rhetoric and composition to disrupt colonial images, visions, myths, stereotypes, and/or fantasies, replacing them with the complexity of our cultural identities from our own lens.
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Title: Allied studies on total sythesis of cyclic tripeptide TMC-95 via an iridium catalyzed borylation/deborylation strategy and teaching organic chemistry in "words"
Creator: Shen, Fangyi
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Arylboronate esters are versatile synthetic building blocks. Iridium catalyzed C-H activation/borylation reactions are a green way of making such building blocks as these reactions often obviate the need for prior functionalization (e.g. halogenation), the use of pyrophoric reagents, cryogenic conditions, etc. Installation of multiple boron substituents about the starting arene and then Ir catalyzed selective deborylation of the individual borons can allow for the formation of an even greater...
Show moreArylboronate esters are versatile synthetic building blocks. Iridium catalyzed C-H activation/borylation reactions are a green way of making such building blocks as these reactions often obviate the need for prior functionalization (e.g. halogenation), the use of pyrophoric reagents, cryogenic conditions, etc. Installation of multiple boron substituents about the starting arene and then Ir catalyzed selective deborylation of the individual borons can allow for the formation of an even greater diversity of borylated building blocks.The regioselectivity of Ir-catalyzed borylation is usually driven by sterics, however heterocycles are known to borylated at positions that exhibit heightened C-H acidity through the influence of the heteroatom. The regioselective borylation attained with a tryptophan derivative has been utilized in the development of a novel convergent route to the TMC-95 core. While pursuing a model synthesis of this natural product, the ability of bismuth salts to catalyze deborylations was discovered. These bismuth salts mediated methods can be highly selective in the in the deborylation of di and triborylated indoles. Furthermore, bismuths compounds are safe and less expensive as compared to the Ir-catalysts that facilitated deborylation. Numerous screening experiments on both substrates and other metal salts afforded a better understanding of how these novel deborylations can be applied in various synthetic settings and provided insight into possible mechanisms.Also, while I was a teaching assistant and a fixed-term instructor during my graduate studies at Michigan State University, I gradually realized that teaching is my passion and I am prepared to start my independent career and be an independent thinking teacher for the organic chemistry area.Owing to the nature of the subject, organic chemistry can be very visually distracting, and the image can be overpowering during student's learning. Like it or not students will try memorization first, our hypothesis is that once they know the "organic transformation formula" in words, via memorization or any other method, then introducing them to the structures of these functional groups will come with added context, and once they make that jump from word to structure they will be in a better position to understand reaction mechanisms. More importantly, understanding those reaction mechanisms will enable the student to progress to more complex topics.By introducing functional group transformations without the "clutter" of structures, we predict that once structures are introduced students will prioritize what's important because they will have trained their minds to ask what is the functional group, not "where did I see that structure in my notes".In short, we aim to train students to focus their attention on the reactive functional group of an organic molecule by emphasizing the use of WORDS to describe functional group transformation and teach the organic chemistry as the second language.
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Title: Labor market outcomes of restatements for corporate accountants
Creator: Shen, Lulu
Date: 2018
Collection: Electronic Theses & Dissertations
Description: This study examines the impact of restatements on the labor market outcomes for corporate accountants. I use LinkedIn to identify a comprehensive sample of corporate accountants who work for firms that restated their financial statements between 2004 and 2014. Using a difference-in-differences research design, I find that corporate accountants experience a higher turnover and a worse promotion prospect after restatements are announced, compared to a control sample of human resources...
Show moreThis study examines the impact of restatements on the labor market outcomes for corporate accountants. I use LinkedIn to identify a comprehensive sample of corporate accountants who work for firms that restated their financial statements between 2004 and 2014. Using a difference-in-differences research design, I find that corporate accountants experience a higher turnover and a worse promotion prospect after restatements are announced, compared to a control sample of human resources professionals within the same firm. The increase in turnover is more pronounced for senior internal auditors, and in firms with more severe restatements. I also find that senior internal auditors experience a higher turnover but not a worse promotion prospect before restatements are announced, compared to senior corporate accountants. Overall, my findings suggest that corporate accountant experience adverse labor market outcomes after restatements are announced. Internal auditors could minimize the adverse labor market outcomes of restatements by proactively departing.
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Title: Social Media Disclosure and Analysts as Information Intermediaries
Creator: Lee, Kwangjin
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Using a sample of S&P 500 firms over the period 2012–2014 and Twitter data, I investigate the effect of social media disclosure on financial analysts as information intermediaries. On one hand, social media is a low-cost mechanism for direct communications from the firm to its investors, so may substitute for information intermediation by analysts. On the other hand, following Mosaic theory (Pozen, 2005), analysts (i.e., the crowd of the experts) have a comparative advantage at placing...
Show moreUsing a sample of S&P 500 firms over the period 2012–2014 and Twitter data, I investigate the effect of social media disclosure on financial analysts as information intermediaries. On one hand, social media is a low-cost mechanism for direct communications from the firm to its investors, so may substitute for information intermediation by analysts. On the other hand, following Mosaic theory (Pozen, 2005), analysts (i.e., the crowd of the experts) have a comparative advantage at placing relevant pieces of information into the broader mosaic, implying that the importance of analysts as information intermediaries may increase with the volume of tweets released by the firm and by the crowd of “the public”. I find firms’ financial tweets are associated with larger analyst following and lower analyst forecast error. This finding is consistent with analysts using social media information as a complement to other information sources, providing richer analyses to investors. I also find that the market reaction to analysts' forecast revisions varies positively with the level of social media activity. Together, these findings suggest that social media disclosure serves as a complement to information processing by analysts, as opposed to a substitute. This paper contributes to the literature on financial analysts by providing evidence that even in the era of social media disclosure, the role of analysts as information intermediaries remains important for the efficient functioning of capital markets. It also contributes to the literature on the impact of social media on capital markets by providing a deeper understanding of the impact of unregulated and unstructured disclosure on the general information environment of financial markets.
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Title: Effects of flexibility and security on the decision to work for ride-sharing services
Creator: Hong, Soo Jeong
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Firms in the sharing economy have developed numerous innovative services. Using the power of advanced information and communication technologies and distributed computing, they have reorganized production of these services in ways that are altering the landscape of employment and working conditions more broadly. Although this transformation has provided participants with more degrees of flexibility in their work schedule and location, there is also evidence that an increasing number of...
Show moreFirms in the sharing economy have developed numerous innovative services. Using the power of advanced information and communication technologies and distributed computing, they have reorganized production of these services in ways that are altering the landscape of employment and working conditions more broadly. Although this transformation has provided participants with more degrees of flexibility in their work schedule and location, there is also evidence that an increasing number of individuals face unreliable income prospects and limited or no benefits. This dissertation investigates the effects of granting providers of ride-sharing services, a menu of contracts with varying flexibility on their willingness to offer their services through a platform. Ride-sharing is one of the largest sectors in the sharing economy and can provide insights that can apply to other services in this emerging sector. Using a choice experiment with 406 participants, the study examines how diversification of contractual attributes (minimum required driving hours, minimum wage guarantee, benefit plans, and the amount of auto insurance deductible) affects drivers’ willingness to work for the online platform. It also investigates whether service providers’ preferences for flexibility and stability in the platform business are influenced by alternative employment options. Results show that the willingness to work for ride-sharing generally increases when the ride-sharing company provides a minimum wage guarantee, a company-sponsored benefit plans, and technological features which protect drivers from unwanted incidents by passengers. Drivers are willing to accept work conditions specifying minimum required driving hours for ride-sharing in return for the ability to participate in a ride-sharing company-sponsored benefits. Additionally, finding suggest a negative association between drivers’ willingness to work for ride-sharing platforms and the perceived job flexibility of their primary job. A similar relation exists between the willingness to work for ride-sharing and perceived security of their primary job. Finally, the results show a positive association between the willingness to work for ride-sharing platforms and contract flexibility of workers’ primary job. Overall, the dissertation contributes to the research literature on the sharing economy, platform governance, and the emergent research on the role of work conditions on labor supply. It offers practical insights on how platform design and governance can contribute to more stable and extensive supply of services on the platform that can contribute to development of more sustainable and valuable business models.
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Title: The design and organisation features of two online courses : a case study of their emergence and evolution
Creator: Richards, Kari
Date: 2017
Collection: Electronic Theses & Dissertations
Description: This study reports the findings of a qualitative case study that examined how elements of design and organization were conceptualized and enacted in two graduate level online courses, and, how these conceptualizations and enactments evolved. Data was collected through interviews and ‘think-alouds’ with the course instructors and through screen captures of the course home pages. The Community of Inquiry Framework (CoI) (Garrison, Anderson, & Archer, 2000) was used as a lens to analyze the data...
Show moreThis study reports the findings of a qualitative case study that examined how elements of design and organization were conceptualized and enacted in two graduate level online courses, and, how these conceptualizations and enactments evolved. Data was collected through interviews and ‘think-alouds’ with the course instructors and through screen captures of the course home pages. The Community of Inquiry Framework (CoI) (Garrison, Anderson, & Archer, 2000) was used as a lens to analyze the data for the Design & Organization element of the framework’s concept of Teaching Presence. The analysis identified patterns in the five features of the Design & Organization element: Setting Curriculum, Designing Methods, Establishing Time Parameters, Utilizing the Medium, and Establishing Netiquette. The data shows variation in the way most of the features are conceptualized and enacted in the online courses, with some exceptions. These variations reflect the different experiences, expectations, and logic of the two instructors, while the exceptions reflect the influence of external norming agents such as the Learning Management System or institutional guidelines. The results indicate a wider range of possibilities in course design and organization than the CoI framework has been conceptualized to account for, which has implications for the various programs and institutions using the framework as an instrument for their evaluation of online courses.
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Title: Filtration of Phytophthora and Pythium zoospores in irrigation water
Creator: Jeon, Sangho
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Phytophthora and Pythium are commonly known as water molds, and can cause enormous damages to many floriculture and vegetable crops worldwide, including seedling damping-off, stunting, and crown, stem and root rot. It is challenging to control these pathogens because plants can be infected and do not show symptoms until the disease is too advanced to respond to treatment. The pathogens can also easily develop resistance to effective fungicides. As the zoospore movement with water flow is a...
Show more"Phytophthora and Pythium are commonly known as water molds, and can cause enormous damages to many floriculture and vegetable crops worldwide, including seedling damping-off, stunting, and crown, stem and root rot. It is challenging to control these pathogens because plants can be infected and do not show symptoms until the disease is too advanced to respond to treatment. The pathogens can also easily develop resistance to effective fungicides. As the zoospore movement with water flow is a major transmission pathway of these pathogens, understanding the transport of zoospores in natural and engineered systems is critical to developing strategies to control the pathogens in both field and greenhouse crops. Thus, the first study investigated the transport and retention of Phytophthora. capsici zoospores in saturated columns packed with iron oxide coated sand (IOCS) or uncoated sand in Na+ or Ca2+ background solution at pH 7.2 or 4.4, in combination with XDLVO interaction energy calculations and microscopic visualizations. Significantly more encysted zoospores were retained in IOCS than in uncoated sand, and at pH 4.4 than at pH 7.2, which likely resulted from increased electrostatic attraction between zoospores and grain surface. At pH 7.2, up to 99% and 96% of the encysted zoospores were removed in IOCS and uncoated sand, respectively, due to a combination of strong surface attachment, pore straining, and adhesive interactions. Motile biflagellate zoospores were more readily transported than encysted zoospores, thus posing a greater dispersal and infection risk. The second and third studies were conducted in a greenhouse to demonstrate a proof-of-concept of using fast-flow filtration to control Phytophthora and Pythium diseases in greenhouse floriculture and vegetable crops. The second study showed that Pythium aphanidermatum could be effectively removed by the fast-flow sand and AC filters at low water pressure. The rapid sand filter had the best performance because no decrease in the poinsettia quality was observed when compared to the non-inoculated control plants. Because the AC filter could also remove the essential nutrients from the irrigation water, and cause the Fe deficiency in the poinsettias, it is less desirable to be used unless the nutrients can be supplied separately instead of through irrigation water. The third study found that the filter with iron oxide coated media [IOCM] could effectively protect the squash plants from Phytophthora capsici, but caused the nutrient deficiency in the squash. The sand filter could not prevent, but only slow the disease development in the squash. Again, it shows that the IOCM filter has the potential to be used in treating irrigation water in the greenhouse vegetable production, but sufficient nutrients also need to be provided. Overall, the results suggested that physical removal of pathogens using fast-flow filtration can overcome many limitations of fungicide application, and may be a promising alternative for disease management in greenhouses."--Pages ii-iii.
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Title: Resistance is not futile : exploring user resistance in technical communication
Creator: Nguy1EBDn,0302 Minh Tâm (Graduate of Michigan State University)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Despite ongoing investments to technology and usability in technical communication—and despite ongoing commitments to humanistic perspectives concerning those two domains—scholars of technical communication have yet to explore the topic of “user resistance” explicitly. User resistance gained prominence in fields like Information Technology (IT), Management Information Systems (MIS), and related fields and has traditionally been conceptualized as oppositional, hostile, or adversarial—a...
Show moreDespite ongoing investments to technology and usability in technical communication—and despite ongoing commitments to humanistic perspectives concerning those two domains—scholars of technical communication have yet to explore the topic of “user resistance” explicitly. User resistance gained prominence in fields like Information Technology (IT), Management Information Systems (MIS), and related fields and has traditionally been conceptualized as oppositional, hostile, or adversarial—a phenomenon meant to be avoided before it occurs. Because of this, traditional definitions of user resistance value the systems with which users engage, with little work theorizing the contexts, behaviors, and agencies of actual users. My dissertation responds to this lack of a user-centered approach by offering a thick literature review that examines how resistance is defined and situated across a range of scholarship. From this literature review, I offer a theory of user resistance that draws on the concept of “everyday resistance” (Vinthagen & Johanssen, 2012) to value users and their contexts. By situating the work done on resistance and providing a theoretical concept of user resistance, I then rhetorically analyze two examples of user resistance on the social networking site, Tumblr to illustrate how and why users resist in dynamic online spaces. The first example demonstrates how users resist within a system to design changes and the second illustrates the how users resist systems of power and oppression created and upheld (implicitly and explicitly) by the site developers and designers. Through an analysis and discussion of these examples, my dissertation seeks to start conversations about user resistance in the domain of technical communication and pivot existing conversations outside the field from a negative phenomenon meant to be avoided before it occurs, to a productive area of inquiry for technology design. Ultimately, I argue that attending to user resistance allows for a more nuanced and engaged approach to user-centered, participatory, and ethical design principles. By examining user resistance, technical communication researchers and practitioners can attend to the local, contextual, and most importantly dissonant needs of users.
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