Matching Items (12,730)
Filtering by
- Language: English
- Creators: Arizona State University
Description
Previous work indicates that structural changes in the right hemisphere following left hemisphere stroke may be related to language abilities. However, the mechanisms behind this relationship remain unclear, particularly regarding the relative contributions of gray and white matter. The present study examined how structural and diffusion measures in the right hemisphere differ between chronic left hemisphere stroke survivors and matched control subjects, and the relationships between language and cognition measures and these right hemisphere measures. T1-weighted MRI, diffusion tensor images (DTI), and a battery of cognitive tests were obtained from 27 chronic left hemisphere stroke survivors and 44 neurologically intact matched control participants. Cortical and volumetric measures of gray and white matter in regions of interest were obtained from the T1 images and compared between groups, and correlated with behavioral measures. Tract-Based Spatial Statistics and tractography methods from the DTI were examined in a similar manner. The T1 MRI-based analyses revealed that the stroke survivors did not differ from the control group in any of the gray or white matter volume measurements. The cortical thickness and mean curvature analyses identified right lateral frontal and insular ROIs exhibiting thinner and greater curvature (an indication of atrophy) in the left hemisphere stroke survivors compared to controls. The DTI-based results showed that the stroke survivors had lower fractional anisotropy and fewer reconstructed fibers in the right language ventral-stream tracts. Regarding correlations between the right hemisphere measures and behavioral performance, there were no significant results within the DTI data, and only one significant result in the gray matter analyses: faster processing speed was correlated with greater cortical thickness in the right frontal cortex in chronic left hemisphere stroke survivors. Overall, the present study provides support for the idea that the right hemisphere exhibits post-stroke changes, particularly in right dorsal stream gray matter and the ventral stream’s white matter, and that these differences are not captured by T1-imaging alone; in fact, the DTI tract-specific analyses were perhaps the most revealing. Future studies are needed, perhaps incorporating functional neuroimaging, to elucidate how these right hemisphere differences in left hemisphere stroke survivors is related to language recovery.
ContributorsHsueh, Yi-Ting (Author) / Reddy, Corianne (Thesis advisor) / Braden, Brittany (Committee member) / Schaefer, Sydney (Committee member) / Arizona State University (Publisher)
Created2021
Description
The family Cactaceae is extremely diverse and has a near global distribution yet very little has been described regarding the community of viruses that infect or are associated with cacti. This research characterizes the diversity of viruses associated with Cactaceae plants and their evolutionary aspects. Five viruses belonging to the economically relevant plant virus family Geminiviridae were identified, initially, two novel divergent geminiviruses named Opuntia virus 1 (OpV1) and Opuntia virus 2 (OpV2) and Opuntia becurtovirus, a new strain within the genus Becurtovirus. These three viruses were also found in co-infection. In addition, two known geminiviruses, the squash leaf curl virus (SLCV) and watermelon chlorotic stunt virus (WCSV) were identified infecting Cactaceae plants and other non-cactus plants in the USA and Mexico. Both SLCV and WCSV are known to cause severe disease in cultivated Cucurbitaceae plants in the USA and Middle East, respectively. This study shows that WCSV was introduced in the America two times, and it is the first identification of this virus in the USA, demonstrating is likely more widespread in North America. These findings along with the Opuntia becurtovirus are probable events of spill-over in agro-ecological interfaces. A novel circular DNA possibly bipartite plant-infecting virus that encodes protein similar to those of geminiviruses was also identified in an Opuntia discolor plant in Brazil, named utkilio virus, but it is evolutionary distinct likely belonging to a new taxon. Viruses belonging to the ssDNA viral family Genomoviridae are also described and those thus far been associated with fungi hosts, so it is likely the ones identified in plants are associated with their phytobiome. Overall, the results of this project provide a molecular and biological characterization of novel geminiviruses and genomoviruses associated with cacti as well as demonstrate the impact of agro-ecological interfaces in the spread of viruses from or to native plants. It also highlights the importance of viral metagenomics studies in exploring virus diversity and evolution given then amount of virus diversity identified. This is important for conservation and management of cacti in a global scale, including the relevance of controlled movement of plants within countries.
ContributorsSalgado Fontenele, Rafaela (Author) / Varsani, Arvind (Thesis advisor) / Wilson, Melissa (Committee member) / Majure, Lucas (Committee member) / Van Doorslaer, Koenraad (Committee member) / Wojciechowski, Martin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Differences in the postcanine dentition of primates likely represent dietary adaptations given that the teeth interact directly with foods during mastication. Among early hominins, changes to both molar and premolar morphology are purported to indicate consumption of foods differing in their material properties. Some early hominins, such as the robust australopiths, possess premolars that resemble molars with enhancements to the distal part of the tooth (i.e., the talonid), including additional cusps and/or expanded basins. Such molarized premolars are thought to indicate that these hominins were processing mechanically challenging foods; that is, food items that were either hard or tough. Hypotheses tested in this study evaluated the link between the degree of premolar molarization and consumption of mechanically challenging foods in extant primates. Surface anatomy of the distal-most mandibular premolar (the P4) was quantified using a combination of 3D scans of postcanine dental casts and craniodental landmark data collected from 541 individuals, representing 22 extant primate taxa with well-studied diets and known food material properties. Taxa with more mechanically challenging diets were expected to have premolars with expanded talonids and enlarged P4s (and/or molar rows) relative to several mechanically-relevant size proxies. Taxa consuming high proportions of structural carbohydrates were also expected to have postcanine teeth with high occlusal relief (RFI), sharpness (DNE), and complexity (OPCR). Taxa consuming harder food items were expected to have lower relief and higher complexity, with sharpness determined by the proportion of structural carbohydrates included in their diet. The work presented in this dissertation supports most of these expectations, though talonid expansion per se was not clearly linked to the consumption of any particular diet. Overall, taxa with more mechanically challenging diets generally had relatively enlarged premolars when compared to taxa with softer diets and also differed predictably in their occlusal topography. The results of this dissertation support the functional significance of P4 crown size and measures of dental topography as they relate to diet and have implications for improving dietary inferences from the fossil record.
ContributorsDaly, Elizabeth Susanne (Author) / Schwartz, Gary T (Thesis advisor) / Delezene, Lucas K (Committee member) / Kimbel, William H (Committee member) / Arizona State University (Publisher)
Created2021
Description
Serious or educational games have been a subject of research for a long time. They usually have game mechanics, game content, and content assessment all tied together to make a specialized game intended to impart learning of the associated content to its players. While this approach is good for developing games for teaching highly specific topics, it consumes a lot of time and money. Being able to re-use the same mechanics and assessment for creating games that teach different contents would lead to a lot of savings in terms of time and money. The Content Agnostic Game Engineering (CAGE) Architecture mitigates the problem by disengaging the content from game mechanics. Moreover, the content assessment in games is often quite explicit in the way that it disturbs the flow of the players and thus hampers the learning process, as it is not integrated into the game flow. Stealth assessment helps to alleviate this problem by keeping the player engagement intact while assessing them at the same time. Integrating stealth assessment into the CAGE framework in a content-agnostic way will increase its usability and further decrease in game and assessment development time and cost. This research presents an evaluation of the learning outcomes in content-agnostic game-based assessment developed using the CAGE framework.
ContributorsVerma, Vipin (Author) / Craig, Scotty D (Thesis advisor) / Bansal, Ajay (Thesis advisor) / Amresh, Ashish (Committee member) / Baron, Tyler (Committee member) / Levy, Roy (Committee member) / Arizona State University (Publisher)
Created2021
Description
The Transonic Area Rule, developed by Richard T. Whitcomb in the early 1950s, revolutionized high-speed flight because its insight allowed engineers to reduce and/or delay the transonic drag rise. To this day, it is the rationale behind “coke-bottle” sculpturing (indenting the aircraft fuselage at the wing-fuselage junction) to alter the cross-sectional area development of the body. According to Whitcomb, this indentation is meant to create a smoother transition of cross-sectional area development of the body and consequently would reduce the number of shocks on the body, their intensity, and their shock pattern complexity. Along with this, modeling of a geometry’s transonic drag rise could be simplified by creating a comparable body of revolution with the same cross-sectional area development as the original geometry. Thus, the Transonic Area Rule has been advertised as an aerodynamic multitool. This new work probes the underlying mechanics of the Transonic Area Rule and determines just how accurate it is in producing its advertised results. To accomplish this, several different wave-drag approximation methods were used to replicate and compare the results presented in Whitcomb’s famous 1952 report16. These methods include EDET (Empirical Drag Estimation Technique)4, D2500 (Harris Wave Drag program)6, and CFD (Computational Fluid Dynamics) analysis through SU25. Overall drag increment data was collected for comparison with Whitcomb’s data. More in-depth analysis was then done on the flow conditions around the geometries using CFD solution plots.
After analysis of the collected data was performed, it was discovered that this data argued against Whitcomb’s comparable body of revolution claim as no cases were demonstrated where the comparable body and original body yielded similar drag rise characteristics. Along with this, shock structures and patterns were not simplified in two of the three cases observed and were instead complicated even further. The only exception to this observation was the swept wing, cylindrical body in which all shocks were virtually eliminated at all observed Mach numbers. For the reduced transonic drag rise claim, the data argued in favor of this as the drag rise was indeed reduced for the three observed geometries, but only for a limited Mach number range.
ContributorsArmenta, Francisco Xavier (Author) / Takahashi, Timothy T (Thesis advisor) / Kim, Jeonglae (Committee member) / Rodi, Patrick (Committee member) / Arizona State University (Publisher)
Created2021
Description
The phase change process of freezing water is an important application in several fields such as ice making, food freezing technologies, pharmaceuticals etc. Due to the widespread usage of ice-related products, process improvements in this technology can potentially lead to substantial energy savings. After studying the freezing process of water, the supercooling phenomenon was found to occur which showed a negative effect. Therefore, ultrasound was proposed as a technique to reduce the supercooling effect and improve the heat transfer rate. An experimental study was conducted to analyze the energy expenditures in the freezing process with and without the application of ultrasound. After a set of preliminary experiments, an intermittent application of ultrasound at 10W & 3.5W power levels were found to be more effective than constant-power application, and were explored in further detail. The supercooling phenomenon was thoroughly studied through iterative experiments. It was also found that the application of ultrasound during the freezing process led to the formation of shard-like ice crystals. From the intermittent ultrasound experiments performed at 10W and 3.5W power levels, percentage energy enhancements relative to no ultrasound of 8.9% ± 12.4% and 11.9% ± 24.6% were observed, respectively.
ContributorsSubramanian, Varun (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Rykaczewski, Konrad (Committee member) / Arizona State University (Publisher)
Created2021
Description
Hydration status serves as an essential pillar of human health. Adequate hydration reduces cardiovascular strain, improves the body's ability to thermoregulate, stabilizes mood, and may reduce the risk of physiologic diseases like that of diabetes and urolithiasis. While many studies have shown the importance of adequate fluid intake on hydration status, very few have investigated the influence of dietary food moisture on hydration status. This study collected daily food diaries, daily fluid diaries, and spot urine samples over a 24hr period from 694 participants in Northwest Arkansas participating in the HYBISKUS study. Fluid and food diaries were logged in NDSR and analyzed using JMP while combined spot urine samples were analyzed using a freezing point depression osmometer to retrieve 24hr urine osmolality. Urine osmolality data was extracted from 24hr urine samples and used as the hydration status biomarker for study participants. The average contributions of water from fluids and foods in participants was 79.3 ±9.6% and 20.7 ±9.5% respectively. This study found that dietary food moisture has a significant effect on hydration status in adults with no specific macronutrient groups take precedence over any others in regard to dietary food moisture contributions. These results suggest that there are legitmate reasons to consider dietary food moisture intake when water intake recommendations are made for adults attempting to optimize health or prepare for physical exercise.
ContributorsKleinschmidt, Hunter (Author) / Kavouras, Stavros SK (Thesis advisor) / Sweazea, Karen KS (Committee member) / Katsanos, Christos CK (Committee member) / Arizona State University (Publisher)
Created2019
Description
Personal training is a growing industry as individuals across the U.S. face increasing levels of physical and psychological health issues. Hiring a certified personal trainer (CPT) presents an opportunity to not only become healthier, but also to grow one’s knowledge and abilities; researchers refer to this process as self-expansion. This research sought to specify a path model of the self-expansion process clients experience while training with their CPT. Secondly, this research described clients’ self-reported disclosure patterns with their CPT. Using Amazon’s Mechanical Turk and ResearchMatch, the study sampled N = 392 U.S. residents who reported training with a CPT. Results from the path analysis indicated poor global fit; however, local fit supported several statistically significant paths. Clients’ level of internal motivation was positively associated with their self-disclosure, self-expansion, and self-pruning. Clients’ self-disclosure was positively associated with perceived closeness with their CPT. Contrary to prediction, clients’ perceived closeness was negatively associated with perceived support from their CPT. However, clients’ perceived closeness and perceived levels of support were both positively associated with their reported levels of self-expansion. Regarding clients’ disclosures, results indicated that clients primarily discuss physical training, diet and nutrition, and health concerns. Thematic analysis of self-reported disclosure examples revealed discussion topics including body dysmorphia, loss and grief, mental health, personal relationships, physical health, professionalism, support seeking, trainer sharing, and trust. Theoretical implications for the self-expansion model include support for additional variables in the self-expansion process, including motivation, self-disclosure, perceived support, and self-pruning. Additionally, practical recommendations for CPTs include an awareness of the type of relationship that clients may desire, as closeness may inhibit perceptions of support with training. Further, CPTs should be aware of the disclosures they may encounter, as clients may share intimate information and seek social support. As such, training programs should include sections on active listening and empathy and require CPTs to be knowledgeable of community resources in the event of a disclosure that presents a serious health risk to the client. Additional research is necessary, particularly to investigate closeness in the self-expansion process, as it did not function as expected within service and professional relationships.
ContributorsShufford, Kevin Nelson (Author) / Adame, Bradley (Thesis advisor) / Randall, Ashley K (Thesis advisor) / Mongeau, Paul (Committee member) / Arizona State University (Publisher)
Created2021
Description
Abstract
The following research addresses some of the contemporary problems that individuals experiencing homelessness face; specifically, investigating the decision to forgo shelter services and spend nights in places unfit for human inhabitation, a phenomenon known as sleeping rough. The paper begins with a broad look at the historical roots of homelessness, urbanization and the failure of mental health services, before exploring past attempts at answering the research question, why do the homeless choose to sleep rough? Several seminal studies, most of which were performed in large New York City shelters, gave context to the dangers present within shelters, but, due to both their location and methodologies, failed to capture the nuances of decision making for individuals experiencing homelessness. In order to expand the literature’s understanding of homelessness and the decision to forgo shelters, I conducted 23 in-depth interviews with various individuals embedded in the homeless culture in Phoenix, Arizona, including those experiencing homelessness, shelter employees, service providers, and the police squad designated to work the shelter beat. This thesis also provides information about the unique circumstances of Phoenix shelter services, the majority of which are housed on the Human Services Campus, a cluster of services specialized for homeless outreach. To supplement the information gathered through in-depth interviews, I analyzed crime maps of the Human Services Campus. This information, coupled with the in-depth interviews, helps explain that the homeless avoid the shelter services for a variety of reasons. These include concerns for safety, freedom, and personal property, as well as a longing to maintain dignity and avoid confrontation with shelter staff and security. Mental health and substance abuse implications are also discussed.
ContributorsHughes, Andrew David (Author) / Scott, Michael (Thesis advisor) / Maguire, Edward (Committee member) / Telep, Cody (Committee member) / Arizona State University (Publisher)
Created2021
Description
Academic advisors play a critical role in student success within United States institutions of higher education. Although uniquely positioned to contribute to important institutional and student outcomes, academic advising is identified in the literature as an emerging profession, often delegitimizing advisor authority and limiting their contribution to institutional objectives. A review of the literature explores the history academic advising, and the current state of professionalization of the field. Additionally, entrepreneurial mindset is introduced as a framework of practice for professional agency. As a field working to professionalize itself within the higher education context, academic advisors must be able to fully participate and contribute to the process of developing innovative practices within the contexts of their institutions. This mixed-methods study drew upon proactive work behavior as defined by Hackman and Oldham to understand how academic advisors demonstrate and perceive their professional agency and ability to make decisions when working with students in the context of their role. Findings suggest professional agency as a construct exists not as a stand-alone concept, but rather as part of an ecosystem within the institution that includes layered systems, structures, and cultures which influence advisor behaviors and how they navigate decision-making. Implications include considerations for academic advising leaders and administrators, specifically related to departmental structures and advisor perceptions of their professional agency. This study contributes to the advising literature in the area of professionalization, with implications for scholarship and practice that can address gaps in the current scholarship.
ContributorsRudd, Melissa (Author) / Basile, Carole (Thesis advisor) / Kim, Jeongeun (Committee member) / Mcintyre, Lisa (Committee member) / Arizona State University (Publisher)
Created2021