ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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Description
Decay of plant litter represents an enormous pathway for carbon (C) into the atmosphere but our understanding of the mechanisms driving this process is particularly limited in drylands. While microbes are a dominant driver of litter decay in most ecosystems, their significance in drylands is not well understood and abiotic drivers such as photodegradation are commonly perceived to be more important. I assessed the significance of microbes to the decay of plant litter in the Sonoran Desert. I found that the variation in decay among 16 leaf litter types was correlated with microbial respiration rates (i.e. CO2 emission) from litter, and rates were strongly correlated with water-vapor sorption rates of litter. Water-vapor sorption during high-humidity periods activates microbes and subsequent respiration appears to be a significant decay mechanism. I also found that exposure to sunlight accelerated litter decay (i.e. photodegradation) and enhanced subsequent respiration rates of litter. The abundance of bacteria (but not fungi) on the surface of litter exposed to sunlight was strongly correlated with respiration rates, as well as litter decay, implying that exposure to sunlight facilitated activity of surface bacteria which were responsible for faster decay. I also assessed the response of respiration to temperature and moisture content (MC) of litter, as well as the relationship between relative humidity and MC. There was a peak in respiration rates between 35-40oC, and, unexpectedly, rates increased from 55 to 70oC with the highest peak at 70oC, suggesting the presence of thermophilic microbes or heat-tolerant enzymes. Respiration rates increased exponentially with MC, and MC was strongly correlated with relative humidity. I used these relationships, along with litter microclimate and C loss data to estimate the contribution of this pathway to litter C loss over 34 months. Respiration was responsible for 24% of the total C lost from litter – this represents a substantial pathway for C loss, over twice as large as the combination of thermal and photochemical abiotic emission. My findings elucidate two mechanisms that explain why microbial drivers were more significant than commonly assumed: activation of microbes via water-vapor sorption and high respiration rates at high temperatures.
ContributorsTomes, Alexander (Author) / Day, Thomas (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Ball, Becky (Committee member) / Hall, Sharon (Committee member) / Roberson, Robert (Committee member) / Arizona State University (Publisher)
Created2020
Description
The desire to start a family is something millions of people around the globe strive to achieve. However, many factors such as the societal changes in family planning due to increasing maternal age, use of birth control, and ever-changing lifestyles have increased the number of infertility cases seen in the United States each year. Infertility can manifest as a prolonged inability to conceive, or inability to carry a pregnancy full-term. Modern advancements in the field of reproductive medicine have begun to promote the use of Assisted Reproductive Technologies (ART) to circumvent reduced fertility in both men and women. Implementation of techniques such as In Vitro Fertilization, Intracytoplasmic Sperm Injection, and Pre-Implantation Genetic Testing have allowed many couples to conceive. There is continual effort being made towards developing more effective and personalized fertility treatments. This often begins in the form of animal research—a fundamental step in biomedical research. This dissertation examines infertility as a medical condition through the characterization of normal reproductive anatomy and physiology in the introductory overview of reproduction. Specific pathologies of male and female-factor infertility are described, which necessitates the use of ARTs. The various forms of ARTs currently utilized in a clinical setting are addressed including history, preparations, and protocols for each technology. To promote continual advancement of the field, both animal studies and human trials provide fundamental stepping-stones towards the execution of new techniques and protocols. Examples of research conducted for the betterment of human reproductive medicine are explored, including an animal study conducted in mice exploring the role of tyramine in ovulation. With the development and implementation of new technologies and protocols in the field, this also unearths ethical dilemmas that further complicate the addition of new technologies in the field. Combining an extensive review in assisted reproduction, research and clinical fieldwork, this study investigates the history and development of novel research conducted in reproductive medicine and explores the broader implications of new technologies in the field.
ContributorsPeck, Shelbi Marie (Author) / Baluch, Debra P (Thesis advisor) / Maienschein, Jane (Thesis advisor) / Sweazea, Karen (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Eusocial insect colonies have often been imagined as “superorganisms” exhibiting tight homeostasis at the colony level. However, colonies lack the tight spatial and organizational integration that many multicellular, unitary organisms exhibit. Precise regulation requires rapid feedback, which is often not possible when nestmates are distributed across space, making decisions asynchronously. Thus, one should expect poorer regulation in superorganisms than unitary organisms.Here, I investigate aspects of regulation in collective foraging behaviors that involve both slow and rapid feedback processes. In Chapter 2, I examine a tightly coupled system with near-instantaneous signaling: teams of weaver ants cooperating to transport massive prey items back to their nest. I discover that over an extreme range of scenarios—even up vertical surfaces—the efficiency per transporter remains constant. My results suggest that weaver ant colonies are maximizing their total intake rate by regulating the allocation of transporters among loads. This is an exception that “proves the rule;” the ant teams are recapitulating the physical integration of unitary organisms.
Next, I focus on a process with greater informational constraints, with loose temporal and spatial integration. In Chapter 3, I measure the ability of solitarily foraging Ectatomma ruidum colonies to balance their collection of protein and carbohydrates given different nutritional environments. Previous research has found that ant species can precisely collect a near-constant ratio between these two macronutrients, but I discover these studies were using flawed statistical approaches. By developing a quantitative measure of regulatory effect size, I show that colonies of E. ruidum are relatively insensitive to small differences in food source nutritional content, contrary to previously published claims.
In Chapter 4, I design an automated, micro-RFID ant tracking system to investigate how the foraging behavior of individuals integrates into colony-level nutrient collection. I discover that spatial fidelity to food resources, not individual specialization on particular nutrient types, best predicts individual forager behavior. These findings contradict previously published experiments that did not use rigorous quantitative measures of specialization and confounded the effects of task type and resource location.
ContributorsBurchill, Andrew Taylor (Author) / Pavlic, Theodore P (Thesis advisor) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Cease, Arianne (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2022
Description
Nicotine and tobacco use, whether it be through cigarette smoking or other devices, creates negative health conditions in pilots. The literature that was reviewed pertained to nicotine withdrawal symptoms and their negative impact on pilot performance. There have been studies conducted in order to explore how these symptoms impact pilot performance using cigarettes as the only nicotine device and does not specify the nicotine levels or the frequency of use. This thesis extends this work to examine the relationship between the nicotine withdrawal symptoms and the nicotine behaviors of pilots. It was hypothesized that the extent of withdrawal symptoms may differ by device and by nicotine levels and frequency of use, with higher levels and more frequent use being associated with more severe withdrawal symptoms. These behaviors included the device they use to take nicotine whether it be cigarettes, vaporizers, e-cigarettes, or smokeless tobacco. The behaviors also included exploration of how nicotine levels relate to withdrawal symptoms whether the nicotine level is as low as 3mg or high as 36mg. The last relationship that was explored was that between the withdrawal symptoms presented in pilots and how often they used nicotine, whether it be often as every day or less frequent as 1-2 times a year. It was found that there is no statistical relationship between nicotine withdrawal symptoms and the nicotine habits such as device used, nicotine level used, and frequency of use.
ContributorsBartlowe, Halie Marie (Author) / Cooke, Nancy J. (Thesis advisor) / Nullmeyer, Robert (Committee member) / Wende, Anthony (Committee member) / Arizona State University (Publisher)
Created2019
Description
Programmed cell death plays an important role in a variety of processes that promote the survival of the host organism. Necroptosis, a form of programmed cell death, occurs through a signaling pathway involving receptor-interacting serine-threonine protein kinase 3 (RIPK3). In response to vaccinia virus infection, necroptosis is induced through DNA-induced activator of interferon (DAI), which activates RIPK3, leading to death of the cell and thereby inhibiting further viral replication in host cells. DAI also localizes into stress granules, accumulations of mRNAs that have stalled in translation due to cellular stress. The toxin arsenite, a canonical inducer of stress granule formation, was used in this project to study necroptosis. By initiating necroptosis with arsenite and vaccinia virus, this research project investigated the roles of necroptosis proteins and their potential localization into stress granules. The two aims of this research project were to determine whether stress granules are important for arsenite- and virus-induced necroptosis, and whether the proteins DAI and RIPK3 localize into stress granules. The first aim was investigated by establishing a DAI and RIPK3 expression system in U2OS cells; arsenite treatment or vaccinia virus infection was then performed on the U2OS cells as well as on U2OSΔΔG3BP1/2 cells, which are not able to form stress granules. The second aim was carried out by designing fluorescent tagging for the necroptosis proteins in order to visualize protein localization with fluorescent microscopy. The results show that arsenite induces DAI-dependent necroptosis in U2OS cells and that this arsenite-induced necroptosis likely requires stress granules. In addition, the results show that vaccinia virus induces DAI-dependent necroptosis that also likely requires stress granules in U2OS cells. Furthermore, a fluorescent RIPK3 construct was created that will allowfor future studies on protein localization during necroptosis and can be used to answer questions regarding localization of necroptosis proteins into stress granules. This project therefore contributes to a greater understanding of the roles of DAI and RIPK3 in necroptosis, as well as the roles of stress granules in necroptosis, both of which are important in research regarding viral infection and cellular stress.
ContributorsGogerty, Carolina (Author) / Jacobs, Bertram (Thesis advisor) / Langland, Jeffrey (Committee member) / Jentarra, Garilyn (Committee member) / Arizona State University (Publisher)
Created2021
Description
Contraceptives are a vital part of reproductive care by preventing unwanted pregnancy, providing relief to premenstrual syndrome or PMS symptoms, and more. Birth control has been around for many centuries and has given women autonomy over their reproductive health. The Griswold v. Connecticut Supreme Court case in 1965 was the first ruling that made birth control accessible to the public under the law. However, this ruling only pertained only to married couples until the Eisenstadt v. Baird case in 1972. That case gave single women the ability to legally purchase contraceptives for themselves. In the decades since those rulings, many laws and policies have been put into place to give those in lower-income areas the ability to purchase contraceptives as well. With this increase in accessibility, those who use contraceptives, or are thinking of starting birth control, need to understand how to use it, when to use it, and the effects of using contraceptives. In the United States, nurses outnumber doctors by a 4:1 ratio and spend more time with patients than anyone else in a clinic or hospital environment. Nurses, being the main healthcare providers with whom a patient will interact, often are the ones patients ask questions about care and overall advice. Nurses must be able to relay valuable information about treatments or medicines, such as birth control, and give accurate information on the effects such treatments have. Nursing students need to be prepared. However, the amount of information provided, and opinions given might be affected by their nursing education, past experiences with birth control, and more. This project surveys nursing students at Arizona State University on their attitudes, behaviors, and beliefs towards birth control interventions, and how their individual experiences and education influence these perceptions.
ContributorsHiggins, Ilani Elyce (Author) / Gur-Arie, Rachel (Thesis advisor) / Ellison, Karin (Thesis advisor) / Maienschein, Jane (Committee member) / Arizona State University (Publisher)
Created2024
Description
Reactive oxygen species (ROS) including superoxide, hydrogen peroxide, and hydroxyl radicals occur naturally as a byproduct of aerobic respiration. To mitigate damages caused by ROS, Escherichia coli employs defenses including two cytosolic superoxide dismutases (SODs), which convert superoxide to hydrogen peroxide. Deletion of both sodA and sodB, the genes coding for the cytosolic SOD enzymes, results in a strain that is unable to grow on minimal medium without amino acid supplementation. Additionally, deletion of both cytosolic SOD enzymes in a background containing the relA1 allele, an inactive version of the relA gene that contributes to activation of stringent response by amino acid starvation, results in a strain that is unable to grow aerobically, even on rich medium. These observations point to a relationship between the stringent response and oxidative stress. To gain insight into this relationship, suppressors were isolated by growing the ∆sodAB relA1 cells aerobically on rich medium, and seven suppressors were further examined to characterize distinct colony sizes and temperature sensitivity phenotypes. In three of these suppressor-containing strains, the relA1 allele was successfully replaced by the wild type relA allele to allow further study in aerobic conditions. None of those three suppressors were found to increase tolerance to exogenous superoxides produced by paraquat, which shows that these mutations only overcome the superoxide buildup that naturally occurs from deletion of SODs. Because each of these suppressors had unique phenotypes, it is likely that they confer tolerance to SOD-dependent superoxide buildup by different mechanisms. Two of these three suppressors have been sent for whole-genome sequencing to identify the location of the suppressor mutation and determine the mechanism by which they confer superoxide tolerance.
ContributorsFlake, Melissa (Author) / Misra, Rajeev (Thesis advisor) / Shah, Dhara (Committee member) / Wang, Xuan (Committee member) / Arizona State University (Publisher)
Created2024
Description
Lifestyle factors including nutrition, may play a role in the development of cognitive impairment. Previous studies based in the United States have shown that nutrient deficiencies in vitamin B-12 and folate can increase the risk of developing mild cognitive impairment in adults, while high levels of potassium increase the risk of cognitive impairment. Among the Tsimane and Moseten subsistence communities in Bolivia, there is a low prevalence of Alzheimer’s dementia and related diseases, but any impacts of micronutrients on cognitive impairment have not been assessed. Using a mixed longitudinal design to estimate nutrient intake via 855 dietary recall questionnaires (24-hour) from 370 Tsimane and Moseten aged 43-85 years (mean age 62 years, 47% male), a culturally specific dementia assessment (3MSE, KIKA, neurological exam) was conducted, and individuals were diagnosed as having normal cognition, mild cognitive impairment, or dementia. Logistic regressions with clustered standard errors (to account for multiple dietary questionnaires per individual) examined the association between dietary intake and cognitive impairment. Controlling for age, sex, body mass index, and education, those with higher daily caloric intake had a lower odds ratio of cognitive impairment, with every 100 additional calories associated with decreased risk (OR = 0.95, p=0.032). Higher B-12 intake was associated with lower cognitive impairment, while higher potassium intake was associated with greater cognitive impairment. The presented data indicate a correlation between diet and nutrition and cognitive impairment within a subsistence population. This observation underscores the potential tradeoffs individuals face in allocating resources towards survival versus the upkeep of cognitive faculties, reflecting broader considerations in life history strategies.
ContributorsBalasubramanian, Sophia (Author) / Trumble, Benjamin C (Thesis advisor) / Jenkins, Carrie L (Committee member) / Aronoff, Jacob E (Committee member) / Arizona State University (Publisher)
Created2024
Description
Cochlear implants (CIs) restore hearing to nearly one million individuals with severe-to-profound hearing loss. However, with limited spectral and temporal resolution, CI users may rely heavily on top-down processing using cognitive resources for speech recognition in noise, and change the weighting of different acoustic cues for pitch-related listening tasks such as Mandarin tone recognition. While auditory training is known to improve CI users’ performance in these tasks as measured by percent correct scores, the effects of training on cue weighting, listening effort, and untrained tasks need to be better understood, in order to maximize the training benefits. This dissertation addressed these questions by training normal-hearing (NH) listeners listening to CI simulation. Study 1 examined whether Mandarin tone recognition training with enhanced amplitude envelope cues may improve tone recognition scores and increase the weighting of amplitude envelope cues over fundamental frequency (F0) contours. Compared to no training or natural-amplitude-envelope training, enhanced-amplitude-envelope training increased the benefits of amplitude envelope enhancement for tone recognition but did not increase the weighting of amplitude or F0 cues. Listeners attending more to amplitude envelope cues in the pre-test improved more in tone recognition after enhanced-amplitude-envelope training. Study 2 extended Study 1 to compare the generalization effects of tone recognition training alone, vowel recognition training alone, and combined tone and vowel recognition training. The results showed that tone recognition training did not improve vowel recognition or vice versa, although tones and vowels are always produced together in Mandarin. Only combined tone and vowel recognition training improved sentence recognition, showing that both suprasegmental (i.e., tones) and segmental cues (i.e., vowels) were essential for sentence recognition in Mandarin. Study 3 investigated the impact of phoneme recognition training on listening effort of sentence recognition in noise, as measured by a dual-task paradigm, pupillometry, and subjective ratings. It was found that phoneme recognition training improved sentence recognition in noise. The dual-task paradigm and pupillometry indicated that from pre-test to post-test, listening effort reduced in the control group without training, but remained unchanged in the training group. This suggests that training may have motivated listeners to stay focused on the challenging task of sentence recognition in noise. Overall, non-clinical measures such as cue weighting and listening effort can enrich our understanding of the training-induced perceptual and cognitive effects, and allow us to better predict and assess the training outcomes.
ContributorsKim, Seeon (Author) / Luo, Xin (Thesis advisor) / Azuma, Tamiko (Committee member) / Zhou, Yi (Committee member) / Arizona State University (Publisher)
Created2024
Description
This dissertation focuses on “patient work” within the context of chronic illness, with a primary focus on information work related to chronic illness and patients’ establishment of legitimacy and credibility concerning their bodily information. Patient work is the labor and tasks of managing one’s health or the health of another (such as a dependent child) and is a universal and ongoing responsibility for billions of people around the globe. Chronic illness intensifies patient work. This research employs an interdisciplinary approach, spanning health services research, science and technology studies, informatics, and human-computer interaction. Using empirical investigations on patients managing chronic kidney disease and seeking an endometriosis diagnosis, this dissertation explores information work dimensions and the quest for credibility, legitimacy, and authoritative knowledge among patients. The interdisciplinary approach deepens understanding of patient work intricacies and challenges faced by those with chronic illness. This dissertation investigates information work dimensions, emphasizing the quest for, receiving, and passing of information; including tracking, disclosing, and synthesizing health information, spotlighting physical experiences often overlooked in scholarly research. Highlighting the overlooked form of information work involving bodily experiences, the research explores how patients navigate disease management using data from their bodies. This emphasizes legitimacy and credibility built through patients' bodily experiences, deeming them experts in disease management. Examining credibility in bodily information work, especially during the diagnostic quest, this dissertation addresses challenges faced by patients in establishing credibility within professional communities. The choice of chronic illness as a case study is justified by patients' instrumental role in managing treatment and care, often overlooked by empowerment efforts. This research argues that without recognizing patient work, poorly designed systems burden patients, leading to worse health outcomes. This interdisciplinary dissertation provides a deeper understanding patient work by developing a typology of patient work, highlighting new distinct types of patient work such as the information work of bodily experiences, and validates credibility work. This work aims to bridge research gaps between disciplines, shifting healthcare systems to support unaccounted-for patient labor better. Furthermore, this research empowers patients as credible experts in their care through qualitative methods and patient narratives.
ContributorsWhitman, Samantha Alexzandria (Author) / Pine, Kathleen H (Thesis advisor) / Johnston, Erik (Thesis advisor) / Harlow, John (Committee member) / Arizona State University (Publisher)
Created2024