Search results

Title: Network Embeddings for Data Clustering, Transition State Identification, and Energy Landscape Analysis
Creator: Mercurio, Paula
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Many chemical and biochemical systems can be intuitively modeled using networks. Dueto the size and complexity of many biochemical networks, we require tools for efficient network analysis. Of particular interest are techniques that embed network vertices into vector spaces while preserving important properties of the original graph. In this article, we investigate several aspects of node embedding, propose a novel method of generating node embeddings, and explore applications to biochemical...
Show moreMany chemical and biochemical systems can be intuitively modeled using networks. Dueto the size and complexity of many biochemical networks, we require tools for efficient network analysis. Of particular interest are techniques that embed network vertices into vector spaces while preserving important properties of the original graph. In this article, we investigate several aspects of node embedding, propose a novel method of generating node embeddings, and explore applications to biochemical systems. We introduce a new method for generating low-dimensional node embeddings for directed graphs using random walk sampling and demonstrate the usefulness of this method for identifying transition states of stochastic chemical reaction systems, detecting relationships between nodes, and studying the structure of the original network. In addition, we propose an efficient scheme for numerical implementation of network embedding based on deterministic computations of commute times rather than random walk trials. We develop a novel implementation of stochastic gradient descent (SGD) based on a low-dimensional sparse approximation of the original random walk on the graph, and show that this approach can improve the performance of node embeddings. This method can be further extended for entropy-sensitive adaptive network embedding by incorporating principles from metadynamics and hierarchical network embedding, allowing for applications to the analysis of molecular structures. By adjusting the edge weights of the network by a Gaussian term, similarly to the metadynamics approach, we ensure that areas that have already been explored extensively by the random walk (i.e., the edges with the largest weights) will be de-emphasized over time, allowing additional iterations of the embedding process to reveal details about other areas of the graph. We show that this approach lends itself well to systems that are influenced by entropy or temperature effects and biochemical systems where the potential energy landscape depends on the system’s configuration at a given time, either by itself or in conjunction with transition path theory. We demonstrate the effectiveness and performance of each of our methods on several datasets and biochemical examples.
Show less

Title: INVESTIGATING TEST DELIVERY MODES WITHIN VIDEO-CONFERENCED ENGLISH SPEAKING PROFICIENCY ASSESSMENT
Creator: Choi, Jin Soo
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Nonverbal behavior is essential in human interaction (Gullberg, de Bot, & Volterra, 2008; McNeill, 1992, 2005). For second language speakers, nonverbal features can be helpful for successful and efficient communication (e.g., Dahl & Ludvigsen, 2014). However, due to the complexity of nonverbal features, language testing institutions have conventionally employed an asynchronous format (e.g., audio-only mode), focusing on the test-taker’s verbal features. Recently, the advance in technology,...
Show moreNonverbal behavior is essential in human interaction (Gullberg, de Bot, & Volterra, 2008; McNeill, 1992, 2005). For second language speakers, nonverbal features can be helpful for successful and efficient communication (e.g., Dahl & Ludvigsen, 2014). However, due to the complexity of nonverbal features, language testing institutions have conventionally employed an asynchronous format (e.g., audio-only mode), focusing on the test-taker’s verbal features. Recently, the advance in technology, and most importantly, the coronavirus pandemic (COVID-19) outbreak in late 2019 and early 2020, have accelerated the use of video-conferencing applications in educational contexts, including speaking tests (Nakatsuhara, Inoue, Berry, & Galaczi, 2021). Accordingly, the synchronous test delivery mode (video-conferencing), which presents test-takers’ visual information, is a timely and necessary approach to addressing the impact of nonverbal features on L2 oral communication. In response to these issues, I investigated the comparability of different delivery modes of speaking proficiency assessment. This study aimed to understand the dimensionality of the measured speaking construct and the impact of test-takers’ visual information on rater behavior. Two datasets were used to address the research goals: first dataset (i.e., dataset 1) included scores of 110 test-takers, assessed by eight trained raters; second dataset (i.e., dataset 2) included scores of 284 prospective international teaching assistants (ITAs), assessed by 12 professional and certified raters. I collected dataset 1, and English language learning and testing program at a Midwest University provided dataset 2. I used two quantitative techniques to analyze both datasets: confirmatory factor analysis (CFA) and Multifaceted Rasch model (MFRM) analysis. For dataset 1, I qualitatively analyzed the raters’ verbal reports. Dataset 1 had an asynchronous format; all test-takers’ performances were recorded for rating. Eight trained raters gave scores to the audio-recorded and video 1 mode (test-taker and test giver were displayed). Three weeks later, the raters assessed video 2 mode (only test-taker’s visual information was displayed). Within one month, raters participated in a one-on-one semi-structured interview. Dataset 2 stems from an operational testing context. This dataset has only scores, as I borrowed the data from the operational English testing program at the university. The scores were first given by examiners in a synchronous format (Live mode) and later by raters in an asynchronous format (Recorded mode). CFA findings indicated the multi-dimensional aspect of the underlying construct of speaking for both datasets, but the high inter-correlations showed that these are associated. Findings of MFRM revealed that raters showed leniency when rating (a) video mode over audio-only mode (dataset 1) and (b) synchronous mode over asynchronous mode (dataset 2). Findings suggest that using the video-conferenced delivery mode may be beneficial. However, the degree of usefulness across video modes differed, and how the raters utilized test-takers’ nonverbal behaviors (e.g., gaze) varied. Thus, I decided that further investigation is needed to sufficiently support the use of video-conferencing applications to complement the physical face-to-face delivery mode. Overall, future research is highly recommended regarding the standardization of scoring of nonverbal features about the types of video mode, which would assist with the practical and valid application of virtual speaking tests.
Show less

Title: Accountability Through Programmatic Goods Distribution : The Ghanaian National Health Insurance Scheme
Creator: Anderson, Stephen Edward
Date: 2022
Collection: Electronic Theses & Dissertations
Description: One way in which political leaders gain support in democratic systems is by distributing goods to citizens. Theories of accountability suggest that when political authorities provide these goods to citizens, they will be rewarded. Yet, incumbents have at their disposal multiple mechanisms through which they can distribute goods to citizens. Generally, goods are either distributed through programmatic or non-programmatic means. This dissertation evaluates how the mechanism through which goods...
Show moreOne way in which political leaders gain support in democratic systems is by distributing goods to citizens. Theories of accountability suggest that when political authorities provide these goods to citizens, they will be rewarded. Yet, incumbents have at their disposal multiple mechanisms through which they can distribute goods to citizens. Generally, goods are either distributed through programmatic or non-programmatic means. This dissertation evaluates how the mechanism through which goods are distributed influences the ways in which citizens evaluate goods performance and political leaders. I address this question by focusing on the distribution of healthcare in the West African country of Ghana. I propose a theory to explain the process by which individuals reward or punish incumbent leaders for healthcare provision distributed via a national health insurance scheme (programmatic distribution) and targeted monetary transfers (non-programmatic distribution). The central insight proposed by the theory is that the characteristics of healthcare distribution via a national insurance scheme lead individuals to evaluate incumbent leaders based on the quality of goods they receive, while the nature of healthcare distribution through targeted transfers leads individuals to evaluate incumbents based not on the quality of goods they acquire, but on their receipt of a transfer. Interview and survey research accord with these propositions. I find that individuals are more likely to sanction incumbents for poor performance when low-quality healthcare goods are distributed through a national insurance scheme. When these same low-quality goods are acquired via monetary handouts, individuals are less likely to sanction incumbents for the quality of said goods. In the latter case, poor performance is not associated with the quality of healthcare goods acquired by citizens, but whether or not the necessary resources for the acquisition of these goods were dispensed by incumbents. I contribute to the literature on goods distribution and accountability and provide novel theory and evidence on the impact of programmatic distribution and incumbent support.
Show less

Title: Investigating Cognition in Howard Engel's Memory Book : Literary Interventions and Intercessions in Scientific Models of Memory
Creator: Cave, Kylene N.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Crime fiction orbits around the concept of memory. At its core, crime narratives are concerned with reconstructing the past, bringing to light the events surrounding the criminal mystery. Memory also manifests in the genre’s detective figures, its modes of detection, and in the eyewitness testimonies used to solve the criminal mystery. In most crime narratives memory operates as a simplistic plot device used to temporarily complicate the mystery and, as such, it is rarely read beyond the...
Show moreCrime fiction orbits around the concept of memory. At its core, crime narratives are concerned with reconstructing the past, bringing to light the events surrounding the criminal mystery. Memory also manifests in the genre’s detective figures, its modes of detection, and in the eyewitness testimonies used to solve the criminal mystery. In most crime narratives memory operates as a simplistic plot device used to temporarily complicate the mystery and, as such, it is rarely read beyond the cursory scope of trauma. This dissertation, however, argues that crime narratives depicting extreme and rare cases of memory—like amnesia—help trace the boundaries around average functioning memory and reveal useful ways for conceptualizing how memory functions, and what disciplines have the impetus to do so. In this dissertation I argue that Howard Engel’s novel, Memory Book (2005), examines the complexities of memory by accomplishing three narratological tasks, distinguishing it from other crime fiction narratives and their more traditional handling of issues of memory and recall. The first task involves placing memory at the center of the narrative and elevating the mystery of the mind to the forefront of the plot. In placing memory at its center, the novel pushes back against traditional and widely popular scientific models of memory as merely the process of remembering and forgetting, advocating for a theory that is more complex and heterogenous. The second narratological task involves the novel’s ability to act as a literary intercessor on behalf of the sciences to translate and disseminate theories of memory to the layperson. Within this task, however, I assert that the novel not only passively intercedes, but actively intervenes in the study of memory by highlighting the inherent limitations of purely scientific or medical models of memory. In exposing these constraints, the novel also suggests a blended, transdisciplinary approach to conceptualizing human memory function and the mind. Lastly, the final task asserts that Memory Book is distinct because its narrative is infused with elements of lived experience, elements the scientific method is incapable of capturing in its probing of memory and cognition. Pointing specifically to Engel’s authorship and the circumstances surrounding the narrative’s composition following a stroke, I argue that the text intentionally blurs the boundaries between reality and fiction as a way of investigating the real-world implications of wrestling with memory loss and brain-injury based amnesia. Each of these narratological tasks is systematically analyzed by engaging with the Howard Engel’s memoir—The Man Who Forgot How to Read—deeply engaging with the novel’s paratextual elements, and through a detailed close reading of the novel.
Show less

Title: USING NOVEL EXPERIMENTAL PROCEDURES TO ELICIT CONSUMER FOOD PREFERENCES AND DEMAND UNDER DIFFERENT CHOICE ENVIRONMENTS
Creator: Kilders, Valerie
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The food system is in a constant state of change driven by the social and bio-physical environment. Acknowledging the role that innovations and preference adaptations on the consumer side play in this process, in this dissertation I use cutting-edge experimental procedures to assess consumer demand in three areas: food-away-from-home (FAFH), sustainable food products, and new food technologies. In the first chapter I determine the impact dining settings have on consumer demand for FAFH, while...
Show moreThe food system is in a constant state of change driven by the social and bio-physical environment. Acknowledging the role that innovations and preference adaptations on the consumer side play in this process, in this dissertation I use cutting-edge experimental procedures to assess consumer demand in three areas: food-away-from-home (FAFH), sustainable food products, and new food technologies. In the first chapter I determine the impact dining settings have on consumer demand for FAFH, while also evaluating how a tax levied on red meat dishes would impact low- and high-income consumers. Capturing both substitution and complementarity patterns, I employ a food menu basket-based choice experiment approach, which permits respondents to freely pick and combine a range of food items at different price levels. I find that respondent’s orders in the delivery setting are typically higher in calories and most items act as complements for one another, while menu items are substitutes in the dine-in setting. The red meat tax that I simulate is regressive towards low-income individuals in the delivery setting but not in the dine-in setting. Thematically corresponding with the red meat tax, in the second chapter I study the market potential of “low carbon” ribeye steaks. In conjunction with this empirical component, I also propose the use of a reference price informed design that mirrors respondent’s price expectations for actual food shopping situations. I find the market potential of meat with a lower carbon footprint is relatively small, with conventional meat taking up most of the market share. Our results also show that a reference price informed design best describes choices and leads to more conservative market share estimates than traditional designs. One way to achieve a lower carbon footprint could be the use of gene-editing. In my third chapter, I therefore assess consumer preferences and willingness to pay (WTP) for milk from cows gene-edited to produce less methane. In doing so, I also analyze whether and how preferences for new food technologies are affected by information on the climate impact of dairy production. I supplement this analysis with an exploration of what medium of information (video vs. text) has the strongest impact on consumer acceptance and how responses change depending on whether respondents get to opt-in to seeing information or are forced to see the respective information. I find that gene-edited milk is discounted relative to other available alternatives. Results also show that choice outcomes differ between respondents seeking additional information and those remaining willfully ignorant. Giving respondents autonomy over their knowledge gathering is a significant factor in determining choice behavior. In sum, findings from these three chapters can be used to inform producers, policymakers, and the food industry, as well as improve the way food experiments are designed within the realm of food choices and beyond.
Show less

Title: ELUCIDATION AND REPURPOSING OF PLANT DITERPENOID BIOSYNTHETIC PATHWAYS
Creator: Miller, Garret P.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Terpenoids are the largest class of specialized metabolites in plants, with widespread uses ranging from fragrances and cosmetics to biofuels, antifeedants, and pharmaceuticals. Terpenoids are derived from a small set of prenyl diphosphate substrates which are cyclized into different terpene scaffolds by terpene synthases. These scaffolds are then modified by various tailoring enzymes—typically starting with cytochrome P450s—into functionalized terpenoids. Given the structural complexity of...
Show moreTerpenoids are the largest class of specialized metabolites in plants, with widespread uses ranging from fragrances and cosmetics to biofuels, antifeedants, and pharmaceuticals. Terpenoids are derived from a small set of prenyl diphosphate substrates which are cyclized into different terpene scaffolds by terpene synthases. These scaffolds are then modified by various tailoring enzymes—typically starting with cytochrome P450s—into functionalized terpenoids. Given the structural complexity of many of these metabolites, total chemical synthesis is often challenging to achieve at a relevant scale and cost, and as such, biosynthetic methods are increasingly being employed as an alternative for their production. The work presented in this dissertation describes the elucidation of two terpenoid biosynthetic pathways and the repurposing of known pathways to convert synthetic substrates not found in nature. First, three steps constituting the full biosynthetic pathway to leubethanol, an antimicrobial diterpenoid active against multidrug-resistant TB, was elucidated in the Texas Sage (Leucophyllum frutescens). Second, seven steps in the biosynthetic pathway towards structurally complex diterpenoid alkaloids were elucidated in the Siberian Larkspur (Delphinium grandiflorum). Third, twenty-four terpene synthases were screened for activity against twenty synthetic substrate analogs not found in nature, resulting in fifty-six new products and demonstrating the ability to derivatize terpene scaffolds through the derivatization of a starting substrate. In all, this work expands access to different classes of terpenoids through the elucidation of biosynthetic pathways and semi-biosynthesis of terpene scaffolds not found in nature, allowing for more feasible and sustainable production of these structurally complex compounds.
Show less

Title: Lovecraft's Wake : Pessimism and Contemporary Weird Fiction
Creator: Conley, Richard Lance
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation examines select writings from H.P. Lovecraft and a group of contemporary authors of weird fiction in the context of a wake, a term defined in two precise ways. The first meaning of “wake” refers to an influential disturbance in the history of weird fiction left by Lovecraft’s writings, a seismic shift at the level of what the genre represents and the kinds of questions it asks. The second definition of “wake” refers to the fact that someone (or something) has passed, and we,...
Show moreThis dissertation examines select writings from H.P. Lovecraft and a group of contemporary authors of weird fiction in the context of a wake, a term defined in two precise ways. The first meaning of “wake” refers to an influential disturbance in the history of weird fiction left by Lovecraft’s writings, a seismic shift at the level of what the genre represents and the kinds of questions it asks. The second definition of “wake” refers to the fact that someone (or something) has passed, and we, the living, attend a wake to acknowledge this passing. With these two definitions in hand, the project argues that a group of contemporary weird fiction authors are writing in and at Lovecraft’s wake. Put differently, certain aspects of his fictional corpus have been revised by a group of contemporary weird fiction authors such that we can, on the one hand, acknowledge Lovecraft’s undeniable influence and the notion that to compose weird fiction in the present is to find one’s self always already writing in Lovecraft’s wake, and, on the other, to move beyond both some of the more dated questions his writing raises as well as the blatantly racist elements of some of his writing(s). Additionally, the contemporary weird authors examined in this project frame different manifestations of pessimism as a worldview that remains contingent, not on an indifferent cosmos, but on human communities in doomed worlds and the horrors that they inflict on each other in that context. In sum, the authors writing in and at Lovecraft’s wake want us not to combat the persistence of pessimism but rather to learn to accept it such that we can live with others in the fundamentally finite time allotted to each of us in a more peaceful way.
Show less

Title: PERSUADING THROUGH FICTIONAL TELEVISION : A MIXED METHODS INVESTIGATION OF GENRE EXPECTATIONS
Creator: McClaran, Sharon-Nicole
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Genres provide an effective way for viewers to categorize, select, and evaluate entertainment television (TV) programs (Bilandzic & Rössler, 2004; Hawkins et al., 2001). People tend to know, for example, whether they will enjoy a medical drama or animated comedy based on their prior experience watching shows of that genre. Despite growing interest in entertainment media as a vehicle for persuasion, minimal research has considered how genre may influence receptivity to and acceptance of...
Show moreGenres provide an effective way for viewers to categorize, select, and evaluate entertainment television (TV) programs (Bilandzic & Rössler, 2004; Hawkins et al., 2001). People tend to know, for example, whether they will enjoy a medical drama or animated comedy based on their prior experience watching shows of that genre. Despite growing interest in entertainment media as a vehicle for persuasion, minimal research has considered how genre may influence receptivity to and acceptance of persuasive appeals in fictional TV programming (J. Cohen & Weimann, 2000; Grabe & Drew, 2007). Even less work has offered theoretical explanations for why genre may impact the persuasion process. Across three studies, this dissertation, guided by expectancy-violations theory (Burgoon, 1993, 2015), offers a thorough investigation into how audiences consider fictional TV genres and whether those expectations influence the success of subsequent persuasive attempts.In Study 1, qualitative interviews were conducted to gauge how viewers feel about using fictional TV shows for persuasion and whether genre is an influential factor in their assessments. The results provided preliminary evidence that viewers hold strong expectations for the likelihood and appropriateness of persuasive appeals in certain genres. In Study 2, persuasion-relevant expectations, including content credibility, learning potential, and likelihood of distributing an educational message, were tested for ten fictional TV genres (animated comedy, animated drama, comedy, crime comedy, crime drama, general drama, historical drama, medical comedy, medical drama, science-fiction/fantasy). Results of the online survey provided strong statistical support that viewers consider the content of TV genres differently and that these expectations influence hypothetical acceptance of an educational appeal. Lastly, Study 3 offered an experimental manipulation of genre (historical fiction vs. science- fiction/fantasy) to test whether genre expectation violations and message resistance explain the success of entertainment media in facilitating persuasion. Although the hypotheses were not supported in Study 3, post-hoc analyses found genre to influence participants’ perceived persuasive intent, which in turn, influenced attitudes, descriptive norms, and behavioral intention toward daily stretching. The cumulative results of this dissertation stress the importance of genre study in the entertainment media persuasion scholarship and offer several avenues for future research.
Show less

Title: INVESTIGATIONS INTO THE VIRUS-LIKE PARTICLE BACTERIOPHAGE Qβ AS A CARRIER PLATFORM IN CONJUGATE VACCINES AGAINST CANCER AND ALZHEIMER’S DISEASE
Creator: McFall-Boegeman, Hunter Sean
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Traditional vaccines are made of either killed or live-attenuated viruses. Killed virus vaccines may suffer from weak immune responses and live attenuation is an inexact science that can take years. There has been an interest in developing alternative vaccine technologies. One class of vaccine technology that has shown promise is the subunit conjugate vaccine. In such vaccines only antigenically relevant portions of infectious agents are conjugated to a carrier capable of stimulating a...
Show moreTraditional vaccines are made of either killed or live-attenuated viruses. Killed virus vaccines may suffer from weak immune responses and live attenuation is an inexact science that can take years. There has been an interest in developing alternative vaccine technologies. One class of vaccine technology that has shown promise is the subunit conjugate vaccine. In such vaccines only antigenically relevant portions of infectious agents are conjugated to a carrier capable of stimulating a stronger immune response. The use of virus-like particles as carriers in conjugate vaccines has shown promise, allowing for the targeting on non-traditional vaccine targets. In this dissertation we report on the use of the virus-like particle Qβ as a carrier in conjugate vaccines targeting cancer and Alzheimer’s disease. Cancer’s ability to escape the immune response requires a total immune response ensure that cancer does not mutate and return resistant to previously used immunotherapies. Previous use of Qβ-based conjugate vaccines against cancer have focused eliciting humoral responses. Herein we report lessons learned from the attempts to functionalize Qβ to elicit cellular immune response in a manner that would minimize the effect on a potential humoral response. Alzheimer’s disease is one of the most common causes of dementia and is hallmarked by the aggregation of tau. A Qβ-based conjugate vaccine targeting the tau-tau binding sites was synthesized and evaluated. Immunization generated a strong humoral immune response superior to a KLH-based conjugate vaccine targeting the same epitope. Generated antibodies were able to preferentially recognize disease associate forms of tau and stain tau in human tissue.
Show less

Title: SEMI-ANALYTICAL METHOD FOR THE ANALYSIS AND DESIGN OF CYLINDERS WITH CONTROLLABLE ELASTIC POST-BUCKLING RESPONSE
Creator: Imani Azad, Ali
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Research over the past ten years has generated an increased interest in studying elastic structural instabilities as a useful response for smart applications rather than a failure. Buckling under axial compression is a type of structural instability that can be used for rapid geometric transformations (switching) and energy harvesting applications, if the deformations arising from buckling are properly controlled. Controlling transverse deformations due to buckling in slender elements usually...
Show moreResearch over the past ten years has generated an increased interest in studying elastic structural instabilities as a useful response for smart applications rather than a failure. Buckling under axial compression is a type of structural instability that can be used for rapid geometric transformations (switching) and energy harvesting applications, if the deformations arising from buckling are properly controlled. Controlling transverse deformations due to buckling in slender elements usually needs external constraints/boundaries. Short thin-walled cylinders can experience several elastic buckling events under axial compression without additional constraints. However, predicting the post-buckling response in cylinders is very challenging, particularly far in the post-buckling regime since they are highly sensitivity to initial imperfections.The concept of cylinders with non-uniform stiffness distribution (NSD) was recently proposed to localize a cylinder’s buckling events in targeted zones. This notion has been proven effective for controlling the number of elastic buckling events, the sequence at which they occur, and the regions experiencing buckling. However, this information is not enough to design NSD cylinders for smart applications, which requires being able to predict the actual applied force for each buckling event, the end shortening of the cylinder for the buckling event, the drop in force, the drop in strain energy, and the post-buckling stiffness of the cylinder. Here, a semi-analytical model has been developed to predict the elastic post-buckling response of NSD cylinders under compression. The developed semi-analytical model is based on three general steps: • Separate the NSD cylinder into parallel segments, • Simplify and predict the response of each segment, and • Integrate the response of individual segments. The first step in predicting the elastic post-buckling response of a cylindrical segment was to simplify its geometry into a cylindrical panel with uniform thickness. Linear springs are connected to the top and bottom of the uniform cylinder to match the stiffness of the simplified segment to the actual one. Based on classical shell theory, the elastic post-buckling response of a cylindrical panel is solved as a boundary value differential equation using the pseudo-arclength method. Comparing the post-buckling response of four cylinders from the proposed semi-analytical model with the response of the same cylinders from the experiment and finite element analysis showed the effectiveness of the proposed model. Results from the proposed model predict well the axial deformation and force level corresponding to buckling events more accurately than the post-buckling stiffness. The response of cylindrical panels for a large variety of dimensions is needed to design NSD cylinders for targeted post-buckling behavior. Thus, the classic differential equation of the cylindrical panels under axial compression was solved independently of the material's cylinder radius and elastic modulus. These results allowed the development of design maps for several post-buckling responses such as axial strain and stresses corresponding to the first buckling event, force, and energy drops from the buckling event, the secondary (or post-buckling) stiffness of the panel, the radial deformation at the panel center, and the maximum von Mises stress in the panel. By using genetic programming, predictive equations were developed for each design parameter to relate it to the geometry of the panels. Three cylinders were designed using the developed design maps to validate the proposed approach. One NSD cylinder was designed to undergo several buckling events under compression at pre-defined end shortenings. A second NSD cylinder was designed to feature a post-buckling force-deformation response that plateaus at a constant force level. The third cylinder was designed to experience the same force drop at each buckling event and in identical axial end shortenings after the first event. Finite element analyses of the designed cylinders verified that using the proposed design procedure using the developed design maps provides NSD cylinders with a post-buckling response that is very close to the desired one, and the ultimate design goal can be achieved by slight modifications to the geometry of the cylinder. This study advances the knowledge on the elastic buckling and post-buckling response of slender cylindrical shells under axial compression and provides an approach to analyze and design them for a desired far post-buckling response. The proposed framework, which combines the notion of decomposing NSD cylindrical segments into linear and nonlinear springs in series, a semi-analytical model for NSD equivalent panels, and design maps for several nonlinear responses provides insight for designing these elements for smart devices and structures relying on structural instabilities. This work expands the harnessing of elastic instabilities to the area of thin-shell buckling under compression, which has received less attention in comparison to other forms of structural instability.
Show less

Title: The Storyteller’s Granddaughtxr : (Re)Envisioning Methodologies for Healing and Liberation
Creator: Furman, Olivia Ann
Date: 2022
Collection: Electronic Theses & Dissertations
Description: My dissertation is an arts-based embodiment, in the form of an exhibition in the LookOut Gallery of Snyder-Phillips Hall at Michigan State University (MSU). This exhibition is the culmination of my interdisciplinary auto-ethnographic dissertation study, within which I utilize Black feminist-womanist storytelling methodology (Baker-Bell, 2017) and Black womxn's literacies of critical self-reflection, art-making, and Afrofuturist dreaming to articulate my own Black womxn's standpoint (Collins,...
Show moreMy dissertation is an arts-based embodiment, in the form of an exhibition in the LookOut Gallery of Snyder-Phillips Hall at Michigan State University (MSU). This exhibition is the culmination of my interdisciplinary auto-ethnographic dissertation study, within which I utilize Black feminist-womanist storytelling methodology (Baker-Bell, 2017) and Black womxn's literacies of critical self-reflection, art-making, and Afrofuturist dreaming to articulate my own Black womxn's standpoint (Collins, 2002). This collection is an inquiry, a piecing together of quilting, collage, speculative fiction, my story, and the intergenerational stories of other Black womxn and femmes to consider the ways our ancestors, identities, and embodied knowledges inform our method(ologie)s of sustainability, healing, and liberation.*Keywords: womanist, Black feminist, storytelling, interdisciplinary, auto-ethnography*Throughout my work, I use an “x” in words such as womxn, mothxrs & othermothxrs to disrupt binary conceptualizations of gendered identities, and to be inclusive of the diverse range of queer and gendered identities and experiences.
Show less

Title: LIFETIME MEASUREMENTS OF THE NEUTRON-RICH 36,38SI ISOTOPES
Creator: Grinder, Mara Mikelah
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The shell structure of nuclei far from stability evolves from the standard shell modelpicture that accurately describes stable nuclei. Experimental evidence has been given by changes in structural properties of nuclei such as the shell closures. The evolution of shell structure is gradual and must be studied by looking systematically at isotopic or isotonic nuclear chains. Studies of these chains can deepen the understanding of shell structures, magic numbers and the collective natures of...
Show moreThe shell structure of nuclei far from stability evolves from the standard shell modelpicture that accurately describes stable nuclei. Experimental evidence has been given by changes in structural properties of nuclei such as the shell closures. The evolution of shell structure is gradual and must be studied by looking systematically at isotopic or isotonic nuclear chains. Studies of these chains can deepen the understanding of shell structures, magic numbers and the collective natures of nuclei far from stability. The neutron rich silicon isotopes display evidence of shell evolution seen in the ratio of the low-lying excitation energies. 34Si has a closed shell nature with a proton bubble structure which evolves along the isotopic chain to the absence of the N=28 shell closure expected in 42Si. Another complementary way to probe these changes is by studying the reduced transition rates of the first 2+ and 4+ states. The ratio of the reduced transition rates has characteristic values for different collective modes. However, these values are not known for isotopes that are more neutron rich than 30Si. The reduced transition rates can be compared to various theoretical models to understand the changes taking place in this neutron-rich region. This work discusses an experiment that studied 36Si and 38Si to determine the lifetimes of their excited states and to determine the reduced transition rates of the first 2+ and 4+ states in both nuclei. From these B(E2) values, the ratio is calculated and compared to the collective models and shell model calculations. The recoil distance measurement was con- ducted at the National Superconducting Cyclotron Laboratory using the S800 Spectrograph, the GRETINA array, and the TRIPLEX plunger. The experiment successfully measured the lifetimes of the 2+1 and 4+1 states in 38Si and the 4+1 and 6+1 states in 36Si. Results from the measurement included the confirmation of the 2383-keV state in 38Si that had only been seen once before. The B(E2) values determined from the experiment indicate the reduced collectivity for the first 4+ states of 36,38Si indicating the persistence of the N=20 magic number through 36Si and 38Si.
Show less

Title: DESIGNING OUR FREEDOM : A NARRATIVE INQUIRY AND VISUAL RHETORICAL ANALYSIS OF BLACK WOMEN ENTREPRENEURS DIGITAL CONTENT STRATEGY ON SOCIAL NETWORKING SITES
Creator: Wourman, Ja'La Janice
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This study explores the role of race and identity in Black women entrepreneurship and how each of these play a part when developing content for online audiences. The purpose of this study was to better understand how our intersecting identities are important to draw upon or consider, when conducting research in work-place studies or entrepreneurship for technical and professional communication scholars. And with the rise of digital platforms, I wanted to better understand if the...
Show moreThis study explores the role of race and identity in Black women entrepreneurship and how each of these play a part when developing content for online audiences. The purpose of this study was to better understand how our intersecting identities are important to draw upon or consider, when conducting research in work-place studies or entrepreneurship for technical and professional communication scholars. And with the rise of digital platforms, I wanted to better understand if the entrepreneurial journey factors into the design process of developing content for online audiences. To answer these questions, I used a narrative inquiry approach to conduct 5 separate interviews for each of my participants. The purpose of the interviews was to amplify the voices of each of my participants drawing from Patricia Hill Collins and the Combahee River Collective’s Black feminist theory. I then conducted a content analysis of 3 images from each of my participants business Instagram profiles, to demonstrate how design and cultural background can play a role in developing content. The results from this study revealed 3 major outcomes from each of the interviews and 4 emerging themes in the images used for all 5 participants content analysis of Instagram. Together, the themes and outcomes show a direct correction of race, culture, and design in content strategy. Using this data, I was able to develop tenets to help scholars and practitioners imagine a culturally centered design framework for developing content for diverse audiences and situations.
Show less

Title: AGGRESSION AND THE GUT-BRAIN AXIS
Creator: Kwiatkowski, Christine Carole
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Violence is a widespread public health and justice system problem with far-reaching consequences for victims, offenders, and their communities. Aggression, the cognitive and behavioral antecedent to violent action, is mainly understood in terms of the psychosocial risk factors that increase the likelihood of aggressive behavioral strategies. Neighborhood context is a principal risk factor for violent crime perpetration, but the mechanisms that mediate the effect of the environment on...
Show moreViolence is a widespread public health and justice system problem with far-reaching consequences for victims, offenders, and their communities. Aggression, the cognitive and behavioral antecedent to violent action, is mainly understood in terms of the psychosocial risk factors that increase the likelihood of aggressive behavioral strategies. Neighborhood context is a principal risk factor for violent crime perpetration, but the mechanisms that mediate the effect of the environment on individual-level aggression behavior are poorly understood, especially the biological factors that may contribute to our understanding of violent behavior. In order to gain a better understanding of mechanisms that precipitate violence in specific geographic contexts, this dissertation explores the relationship between aggression behavior and the gut microbiome, a spatially determined physiological system that affects human health and behavior. Preclinical experiments elucidate the role of the gut microbiome in territorial, reactive aggression behavior in mice. Results show significant differences in gut microbiome composition across the spectrum of murine aggression behavior. Moreover, manipulation of the gut microbiome via administration of short-term antibiotics and sodium butyrate, a short-chain fatty acid byproduct of microbial fermentation, increases aggression behavior. The overall goal of this research is to use basic science findings in mice to better understand how environmental exposures could influence human health and behavior, thus revealing how community health affects individuals and supplying a potential target for future intervention.
Show less

Title: CIRCADIAN RHYTHMS IN LATE PREGNANCY : A ROLE IN THE REPRODUCTIVE AXIS, UTERINE CONTRACTIONS AND PRETERM LABOR
Creator: Duong, Thu Van Quynh
Date: 2022
Collection: Electronic Theses & Dissertations
Description: What drives labor onset remains largely unknown. Understanding the molecular mechanisms defining pregnancy duration and preparing the uterus for labor onset can help improve current treatment strategies to promote or halt labor. Biological processes with a ~24-hour cycle called circadian rhythms are generated by endogenous “clock” transcription factors referred to as the molecular clock, which drives daily changes in cellular functions. To understand the role of circadian rhythms in pregnancy...
Show moreWhat drives labor onset remains largely unknown. Understanding the molecular mechanisms defining pregnancy duration and preparing the uterus for labor onset can help improve current treatment strategies to promote or halt labor. Biological processes with a ~24-hour cycle called circadian rhythms are generated by endogenous “clock” transcription factors referred to as the molecular clock, which drives daily changes in cellular functions. To understand the role of circadian rhythms in pregnancy, we first characterized how the molecular clock of the reproductive axis adapts to pregnancy and found the molecular clock is upregulated. Next, to understand if the molecular clock helps define pregnancy duration, we analyzed gene expression data from pregnant women. We found that low maternal levels of two clock genes increased the risk of preterm birth 5 fold. As preterm birth is driven by a premature increase in uterine contractions, we then asked how time of day impacted uterine contractile response to oxytocin, a hormone that increases uterine contractions and is widely used to induce labor. As model for human pregnancy, mice presented with daily time windows of increased uterine sensitivity to oxytocin. To determine if the molecular clock drives this daily change in sensitivity to oxytocin, we used conditional knockout mice which had the molecular clock ablated in uterine smooth muscle. These mice lost the daily change in sensitivity to oxytocin-induced contractions and presented stronger spontaneous uterine contractions than controls. In conclusion, we show that circadian rhythms have an important role in regulating pregnancy duration and uterine function, where the uterine molecular clock defines daily time windows of enhanced uterine sensitivity to oxytocin.
Show less

Title: Metamodeling in Evolutionary Multi-Objective Optimization for constrained and unconstrained Problems
Creator: Hussein, Rayan
Date: 2022
Collection: Electronic Theses & Dissertations
Description: One of the main difficulties in applying an optimization algorithm to a practical problem is that the evaluation of objectives and constraints often involve computationally expensive procedures. To handle such problems, a metamodel (or surrogate model, or response surface approximations) is first formed from a few exact (high-fidelity) solution evaluations, and then optimized by an algorithm in a progressive manner. However, there has been lukewarm interest in finding multiple trade-off...
Show moreOne of the main difficulties in applying an optimization algorithm to a practical problem is that the evaluation of objectives and constraints often involve computationally expensive procedures. To handle such problems, a metamodel (or surrogate model, or response surface approximations) is first formed from a few exact (high-fidelity) solution evaluations, and then optimized by an algorithm in a progressive manner. However, there has been lukewarm interest in finding multiple trade-off solutions for multi-objective optimization problems using surrogate models. The literature on surrogate modeling for constrained optimization problems is also rare. The difficulty lies in the requirement ofbuilding and solving multiple surrogate models, one for each Pareto-optimal solution. In this study, we propose a taxonomy of different possible metamodeling frameworks for multi-objective optimization and provide a comparative study by discussing advantages and disadvantages of each framework. Also, we argue that it is more efficient to use different metamodeling frameworks at different stages of the optimization process. Thereafter, we propose a novel adaptive method for switching among different metamodeling frameworks. Moreover, we observe the convergence behavior of the proposed approaches is better with a trust regions method applied within the metamodeling frameworks. The results presented in this study are obtained using the well-known Kriging metamodeling approach. Based on our extensive simulation studies on proposed frameworks, we report new and interesting observations about the behavior of each metamodeling framework, which may provide salient guidelines for further studies in this emerging area within evolutionary multi-objective optimization. Results of this study clearly show the efficacy and efficiency of the proposed adaptive switching approach compared to three recently-proposed other metamodeling algorithms on challenging multi-objective optimization problems using a limited budget of high-fidelity evaluations.
Show less

Title: WRITING ASSESSMENT IN MIDDLE SCHOOL STUDENTS : ANALYZING SPELLING WITHIN A MULTIDIMENSIONAL LANGUAGE FRAMEWORK
Creator: Sweet, Lake Eiseler
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Although producing quality written expression is a vital skill, many students in the United States struggle to produce proficient written language. There are many academic and career outcomes related to the ability to produce written expression, yet many schools lack formalized writing assessment and instruction. As such, many questions remain related to individual differences in writing ability and best practices in assessment and instruction. To answer these questions, it is necessary to...
Show moreAlthough producing quality written expression is a vital skill, many students in the United States struggle to produce proficient written language. There are many academic and career outcomes related to the ability to produce written expression, yet many schools lack formalized writing assessment and instruction. As such, many questions remain related to individual differences in writing ability and best practices in assessment and instruction. To answer these questions, it is necessary to establish a model of written expression and what specific variables exist within the model to be used to assess written language. Modern writing assessment theory uses levels of language as a framework with commonly assessed dimensions of accuracy, complexity and productivity. This framework has yet to be firmly established in the literature, and the variables included in each level are just beginning to be explored. One salient variable in writing research, assessment and instruction is spelling ability, and how this ability may influence the production of written language. This study furthers the work by Wilson et al. (2017), Troia and colleagues (2019) and many others (e.g., Berninger et al., 2006; Flower & Hayes, 1981) with the ultimate goal of developing a model of written language to guide assessment and instruction in schools. Specifically, data were drawn from Truckenmiller and colleagues (2020) study piloting a writing assessment tool, Writing Architect, which sampled 526 students from third to eight grades; this study used sixth, seventh and eighth grades with a resulting sample size of 290 students. Results indicated spelling was a significant predictor of writing quality, in that better spelling indicated better writing quality. The same was true for text. For the sentence-level variable, a higher score indicated worse writing quality in a significant way. The word variable did not significantly predict writing quality in the model. The significant interaction between spelling and text variables suggests that the effect of text on writing quality is even higher when spelling ability is also high. Findings highlight the importance of writing and spelling instruction in school. The findings for this age group help identify how writing abilities may change over the trajectory of development and vary individually. Additionally, this analysis echoes the call for further research to establish variables for automated writing assessment.
Show less

Title: DEVELOPMENT OF NOVEL FLUORESCENT PROTEIN TAGS FOR NO-WASH LIVE-CELL IMAGING WITH MINIMUM FLUORESCENT BACKGROUND
Creator: Esmatpour Salmani, Rahele
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Recent fluorescence microscopy technologies have revolutionized many areasof biomedical research. Nonetheless, high brightness, far-red/near infra-red emission, deep tissue penetration, and selective fluorescent imaging with the minimum background are among the most desired novel fluorescent labeling. One of our primary goals is to develop flexible fluorescent protein tags capable of being tailored ad infinitum. We successfully demonstrated the ability to fine-tune the absorption and emission...
Show moreRecent fluorescence microscopy technologies have revolutionized many areasof biomedical research. Nonetheless, high brightness, far-red/near infra-red emission, deep tissue penetration, and selective fluorescent imaging with the minimum background are among the most desired novel fluorescent labeling. One of our primary goals is to develop flexible fluorescent protein tags capable of being tailored ad infinitum. We successfully demonstrated the ability to fine-tune the absorption and emission spectra of protein-bound chromophores over an unprecedented wide range (~200 nm). In contrast to intrinsically fluorescent proteins that are always “ON” in our systems, fluorescent is activated upon covalent binding of ligand and the target protein leading to temporal control of fluorescence. However, the fluorescence background from unbound free chromophore and non-specific binding has always been a deep concern in fluorescent labeling. This Ph.D. research aimed to develop novel proteinbased fluorescent tags emitting in the far-red/NIR region of the spectrum for no-wash background-free live-cell imaging applications. This was accomplished by coupling novel synthetic fluorogenic chromophores with hCRBPII mutants. Unbound free aldehyde ThioPhenol and CyThioPhenol are non-emissive dyes that become highly iii fluorescent upon imine formation with an active site lysine residue engineered deep in the hCRBPII cavity. We created a hydrogen-bonding network around the ThioPhenol hydroxyl group through rational protein engineering that facilitates its deprotonation upon photoexcitation. On the other hand, engineering the target protein to maintain a high iminium pKa resulted in Protonated Schiff Base (PSB) formation. The resultant complex experiences a strong intramolecular charge transfer (ICT), leading to fluorescence and a large bathochromic shift in the emission (~700 nm). The designed protein-based photoacid provides an unprecedented spatiotemporal control for nowash bright NIR imaging. Our most recent report demonstrated that hCRBPII/chromophore complexes could be developed as a photobase where the imine is converted to an iminium upon photoexcitation. In the course of optimizing hCRBPII to promote ESPT of the hydroxyl group, we discovered that ThioPhenol is capable of acting as both a photoacid and a photobase upon a single photoirradiation. When bound as a Schiff base (SB) to protein mutants that maintain a low iminium pKa (~5), engineered to deprotonate the hydroxyl group, a dual ESPT process leads to protonation of the imino to iminium (the photobase) and deprotonation of the hydroxyl to alkoxide (the photoacid). This double ESPT feature is recapitulated in a proteinligand micro-environment, yielding bright protein-dye complexes with unapparelled large pseudo-Stokes shifts (~250 nm). Additionally, the double ESPT ThioPhenol/hCRBPII complexes show fast binding rates (half-life of <3 min) that were successfully used to visualize whole-cell and the nucleus as a fluorogenic tag without any washing steps. Currently, further modifications are in progress to optimize the double ESPT systems with CyThioPhenol and further in-vivo applications.
Show less

Title: Essays on the Economics of Education
Creator: Wood, William Jesse
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation provides three chapters on the economics of education. In the first chapter, I provide evidence that diversifying the labor supply of teachers to better reflect the racial distribution of students improves noncognitive outcomes for students of color without diminishing outcomes for White students. I use administrative data spanning 2007 to 2017 from the Los Angeles Unified School District, one of the most racially diverse school districts in the country, to measure the...
Show moreThis dissertation provides three chapters on the economics of education. In the first chapter, I provide evidence that diversifying the labor supply of teachers to better reflect the racial distribution of students improves noncognitive outcomes for students of color without diminishing outcomes for White students. I use administrative data spanning 2007 to 2017 from the Los Angeles Unified School District, one of the most racially diverse school districts in the country, to measure the effect of student-teacher race matching on various noncognitive and behavior outcomes: GPA, work habits, cooperation, grade retention, suspensions, absences, and a data generated noncognitive index. I mitigate the concern that race matches are endogenous by including school-grade and student fixed effects in a linear regression model. My findings indicate that students of color are expected to experience increases in GPA, work habits, and cooperation and see decreases in suspensions and absenteeism when matched with a teacher of the same race. I do not find statistically significant effects on White students' outcomes. Because noncognitive outcomes lead to higher high school graduation rates, college enrollment rates, and wages, such effects could lead to a tightening in the achievement and wage gap found between students of color and White students. This result can be achieved with an increase in institutional efforts to ensure teacher populations more closely reflect that of their students. The second chapter estimates the impact of race matched faculty (i.e., any teacher outside of a particular student’s classroom) on student test scores. While the student population rapidly diversifies, the teaching corps' diversification continues to lag behind. For example, the proportion of Latino student enrollment in public schools has increased from 11 to 27 percent in just the last two decades. In contrast, the share of Latino public school teachers during this same period has increased from 3 to only 9 percent (Pew Research Center, 2021). If the disparity between student and teacher racial distributions continues to grow, students of color may find it more difficult to benefit from direct student-teacher race matching. However, it may still be possible for students to benefit from same-race teachers even if they are not placed in the same classroom. Using administrative panel data between school years 2008-09 through 2017-18 from Los Angeles Unified School District, I estimate that Latino students see positive impacts of race matched faculty. By basing this study in an area with a large proportion of Latino students and teachers, we can fill a gap within the literature by examining the effects of race match and faculty race match on Latino students. The findings indicate that matching Latino students to racially congruent teachers and faculty can improve math and English Language Arts test scores. Increasing the supply of Latino teachers may provide a crucial catalyst in decreasing the achievement gaps found between Latino and white students. The final chapter continues along the lines of educational equity. The success of many students with disabilities (SWDs) depends on access to high-quality general education teachers. Yet, most teacher value-added measures (VAMs) fail to distinguish between a teacher’s effectiveness in educating students with and without disabilities. I create two VAMs: one focusing on teachers’ effectiveness in improving outcomes for SWDs, and one for non-SWDs. I find top-performing teachers for non-SWDs often have relatively lower VAMs for SWDs, and SWDs sort to teachers with lower scores in both VAMs. Overall, SWD-specific VAMs may be more suitable for identifying which teachers have a history of effectiveness with SWDs and could play a role in ensuring that students are being optimally assigned to these teachers.
Show less

Title: SECOND LANGUAGE LEARNERS’ INDIVIDUAL DIFFERENCES AS A DYNAMIC SYSTEM : EVIDENCE FROM A RUSSIAN IMMERSION PROGRAM
Creator: Pastushenkov, Dmitrii
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Guided by Dynamic Systems Theory (DST) and multidimensional perspectives on individual differences (IDs) in instructed second language (L2) learning (e.g., Larsen-Freeman, 2014; Sun & Zhang, 2020), this longitudinal mixed-methods study focuses on three conceptually different categories of L2 learners’ IDs: working memory (WM), motivation, and the amount of L2 exposure. Despite previous propositions regarding cognitive, affective, and exposure-related IDs being interrelated (e.g., Pawlak, 2012...
Show moreGuided by Dynamic Systems Theory (DST) and multidimensional perspectives on individual differences (IDs) in instructed second language (L2) learning (e.g., Larsen-Freeman, 2014; Sun & Zhang, 2020), this longitudinal mixed-methods study focuses on three conceptually different categories of L2 learners’ IDs: working memory (WM), motivation, and the amount of L2 exposure. Despite previous propositions regarding cognitive, affective, and exposure-related IDs being interrelated (e.g., Pawlak, 2012), including WM and motivation (e.g., Serafini, 2017) and WM and the amount of L2 exposure (e.g., Denhovska et al., 2016), the longitudinal development of motivation and L2 exposure, as well as the effects of WM, motivation, and L2 exposure on learning gains in different skills and at different stages of L2 development have not yet been investigated. In this study, I aimed to address this gap and explore how L2 learners’ motivation and the amount of L2 exposure change over time and how WM, motivation, and the amount of L2 exposure affect learning gains in lexicogrammar, speaking, and writing at different initial proficiency levels. Considering that Second Language Acquisition (SLA) and Instructed SLA (ISLA) research are dominated by studies of more commonly taught languages, I also strove to promote the need for more ecologically valid research with Less Commonly Taught Languages (LCTLs) and investigated IDs in the instructed L2 learning of Russian. The participants were 52 students recruited from an eight-week Russian summer immersion program from four curricular levels (First-Year, Second-Year, Third-Year, and Fourth-Year Russian). The program was conducted online due to the COVID-19 pandemic. The results supported the view of L2 learners’ motivation and L2 exposure as constructs showing stable and dynamic patterns and that different constituents of WM, motivation, L2 Russian exposure, and learning gains were engaged in complex relationships that varied at different curricular levels, language skills, and phases of the study. This dissertation includes a discussion of theoretical implications with regards to DST and the mixed-methods approach as future directions for ISLA studies of IDs, including research with LCTLs. The dissertation also includes a section on practical implications that discusses pedagogical aspects and implications for the development of background questionnaires and placement testing.
Show less

MSU Libraries

Digital Repository

Enabled Filters

Pages

Pages

MSU Libraries

Digital Repository

You are here

Search results

Pages

Pages