More than 38,000 theses and dissertations produced at the University of Arizona are included in the UA Theses and Dissertations collections. These items are publically available and full-text searchable. A small percentage of items are under embargo (restricted).

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  • ISCHEMIA-INDUCED CHANGES IN CONNEXIN 43 PHOSPHORYLATION STATE

    Burt, Janis; Silva-Mendoza, Diego (The University of Arizona., 2021)
    Heart tissue beats synchronously due to the electrical coupling provided by intercellular channels termed gap junction channels. In the ventricles of the heart, these channels are composed of connexin 43 (Cx43); large numbers of these channels localize at the intercalated discs, the site of mechanical as well as electrical coupling in the heart. The colligative properties of these channels support passage of electrical signals from cell to cell, signals that lead all cells of the ventricles (myocytes) to contribute simultaneously to each contraction. Heart attacks, blood clots, or other events that restrict blood flow to (and diffusion of oxygen into) the myocytes for 30 minutes or more, disrupt electrical coupling in the affected (ischemic) region and negatively impact coordinated contraction in the heart, often with deadly effect. Interestingly, loss of blood flow for a brief period of time can protect the heart and electrical coupling from subsequent longer periods of lost blood flow. This protection may, at least in part, reflect phosphorylation, the addition of a phosphate group, to a specific amino acid residue, serine 368 (S368) in the Cx43 protein. Phosphorylation at this residue changes the function of Cx43 channels in a manner that minimizes ischemia-induced damage. In the current project we aim to delineate an accurate time course for phosphorylation of S368, and dephosphorylation of CK1 sites (S325, S328, S330). Dephosphorylation of CK1 sites is associated with ischemic damage. To do so, we are using separate antibodies that specifically detect only the phosphorylated S368 (pS368), and only the phosphorylated CK1 sites (pCK1) in hearts ischemic for 0, 5, 10, 20, and 30’. Results are compared to total Cx43 in the same hearts. Our data suggest that pS368 appears in the first 5-10’ of ischemic time, and that pCK1 levels are reduced simultaneously. Further research into the localization of pS368 and pCK1 Cx43 is necessary to assess the movement of total Cx43 or mechanism of reduction of CK1 Cx43.
  • YUA: THE “YSL” OF U OF A

    Sharkey, Nancy; Grabinski, Alyssa Rose (The University of Arizona., 2021)
    The purpose of this project was to highlight various alumnae from the University of Arizona who have gone on to pursue careers in what many label “soft news.” Here at the University of Arizona, the journalism major focuses on “hard news,” the straight-forward, unbiased, basic description of the facts. The journalism program fails to recognize that entertainment is a growing field, even though many of our own alumnae have gone on to pursue careers in this industry. In this magazine, seven alumnae were interviewed on their career path. These alumnae have worked at places like Teen Vogue, TMZ, Entertainment Tonight, J. Crew, and more. With ever-changing curriculum, my hope is that the journalism program can implement some entertainment, fashion, and lifestyle courses to reflect the ever-growing possibilities of journalism.
  • Coding of the Unseen: Place Cells in Unmarked Reward Influencing Areas

    Fellous, Jean-Marc; Gerken, Blake Anthony (The University of Arizona., 2021)
    Research has shown that the CA1 region of the hippocampus contains specialized pyramidal cells that encode locations and rewards, termed place cells and reward cells respectively. Methodologically, rewards are used to produced preferred areas while adverse stimuli such as a foot shocks are used to elicit avoidance behavior. How positive or aversive areas affect place cell firing is generally unknown but can give important insights into the nature of place cells, reward cells and their interactions. The effects of reward influencing areas was studied using an open octagonal maze using unmarked zones. When a given unmarked zone was entered it would randomly trigger a sound and a reward at one of eight sites of the maze. If the zone was negative, it would instead de-activate an already primed reward zone and trigger a delay before the next reward becomes available. Behaviorally, it was shown that the rats learned to go to the positive zone to receive a reward elsewhere on the maze and avoid the negative zone. Pilot tetrode recordings in CA1 of the dorsal hippocampus further showed intriguing remapping patterns of place fields when an unmarked zone was present. This presents evidence that a rat can learn and encode locations that affect future delivery or withdrawal of rewards even if those locations are themselves devoid of rewards or punishment.
  • A Solution of the d-String Optimal Stopping Problem in Certain Bernoulli Sequences

    Sethuraman, Sunder; Bishop, Derick; Bedrick, Edward J.; Hao, Ning; Watkins, Joseph C. (The University of Arizona., 2022)
    In this thesis, we focus on the construction of an optimal stopping time τ that bestows the greatest probability of identifying the index at which a specific pattern of 0’s and 1’s terminates for the final time within an infinite sequence {I_n }_(n≥1) of independent, but not identically distributed, Bernoulli random variables. In particular, we concentrate on the occurrences of patterns of the form 100⋯001. Since these strings are fully determined by the fixed nonnegative number of consecutive 0’s spanning the initial and concluding 1’s, they are often termed d-strings in the literature, in which the natural number d represents the waiting time until the second 1. As an important application of the general theory that we will develop, we shall examine the d-strings that appear in the Bernoulli sequence {I_n }_(n≥0)={Bern(a⁄((a+b+n-1) ))}_(n≥0), where a>0 and b≥0. Such sequences arise quite naturally in a range of settings, such as in the study of records, rank order statistics, uniformly generated permutations, and Ewens sampling, as well as within the context of Dirichlet processes in theoretical statistics. In a paper published in 2010, Shoou-Ren Hsiau derived the form of the optimal stopping rule τ corresponding to the terminal index of the final 1-string in a Bern(a,0) sequence. In the special case a=1, Hsiau has therefore calculated the best possible stopping time among those targeting the last “consecutive record” 1-string pattern 11 associated with an arbitrary sequence of i.i.d. continuous random variables. We shall generalize Hsiau’s result considerably, showing not only that d-string optimal stopping problems related to Bern(a,b) can be solved for every d∈N, a>0, and b≥0, but also that—just as in the particular case considered by Hsiau (i.e., in which d=1 and b=0)—the associated optimal rules are of threshold type. Furthermore, our proof of this assertion yields a characterization of the threshold in terms of a, b, and d—one that can be computed by any standard mathematical software package. Finally, we investigate the asymptotic tendencies both of the threshold t_(a,b) and of the success probability P(T=τ_(a,b,) ), establishing that 〖lim_(a→∞)〗⁡〖t_(a,b)⁄a^2 〗=1 and that 〖lim_(a→∞)〗⁡P(T=τ_(a,b) )=e^(-1), yet again precisely as in the special case considered by Hsiau. Accordingly, the principal results obtained in this thesis represent substantial generalizations of the results featured in (Hsiau, 2010), typically exploiting entirely different methods of proof than those employed in Hsiau’s paper. To the best of our knowledge, these results are the first specific facts to appear in the literature pertaining to a general type of pattern of 1’s and 0’s in a Bernoulli sequence related to a records process.
  • Assessing the Effect of Temperature on Streptomyces Griseus Growth and Metabolism

    Tfaily, Malak; Rodshagen, Tyler; Ikner, Luisa; McLain, Jean (The University of Arizona., 2022)
    With the current rate of population growth, it is estimated that global food production will need todouble over the course of the next century to sustain healthy diets on the global scale. Given the limited amount of arable land that could be used for agriculture, gains in crop production will need to come from improving current practices rather than from expanding farmlands. The Food and Agriculture Organization (FAO) estimates that 20-40% of yearly crop losses can be attributed to pests, with the majority of damages coming from pathogens. Rhizobacteria like Streptomyces griseus can defend plants from pathogens and even promote plant growth, but it is unknown how this bacterium’s growth and metabolism will respond to rising global temperatures. We used a combination of high resolution FTICR-MS and LC-MS/MS to assess changes in bacterial metabolism (including primary and secondary metabolites) as a function of increasing temperature. Analysis of microbial growth curves and metabolomics data revealed that microbial activity, metabolite abundance/diversity, and the production of compounds beneficial to plants were greatest at 22 ??? intermediate at 35 ??? with practically no activity at 4 ?C. These results suggest that as global temperatures rise, S. griseus may confer fewer benefits to plants. If other rhizobacteria respond in similar ways, current methods of pest and pathogen control must be improved, or new methods must be developed, to reduce crop losses to pathogens. Reducing crop losses to pathogens will be paramount to ensure that global food security is achieved by the end of the century and beyond.
  • Water Usage for Power Generation & Opportunities for Water Reuse Expansion a Study of Salt River Projects Water Usage

    Rock, Channah M.; Dery, Jessica Leah; McLain, Jeannie; Gerba, Charles (The University of Arizona., 2022)
    Increasing demands on limited water resources have made the use of recycled water an attractive option for extending potable water supplies. Recent actions towards the development of the Drought Contingency Plan require Southwestern states, and water users within the States, to develop a plan for more sustainable water usage from the Colorado River. Tasked with protecting the State’s valuable resources now and in the future, the Arizona Department of Water Resources (ADWR) regulates water users, including large-scale power generators, one of the largest waters, within the Active Management Areas (AMAs) through a set of Management Plans. Thermoelectric power generation, accounts for around 40 percent of total water withdrawals in the US; the largest volume of which is used for cooling (Dieter et al., 2018). While less than one percent of power plants in the US use recycled water, over 50 percent are located with ten miles of suitable reclaimed water supplies. By 2025, ADWR will require power plants that produce greater than 25 megawatts of electricity to meet a set of conservation requirements, including using zero liquid discharge systems and increasing cycles of concentration to reduce the volume of cooling tower makeup water. To incentivize the use of recycled water in power generation, the ADWR will provide exemptions for plants that beneficially reuse 100 percent of blowdown water from cooling towers or use reclaimed water for at least 50 percent of water used in cooling towers. The purpose of this study was to identify opportunities for enhanced use of recycled water in power generation, specifically for a fleet of generating stations owned and operated by the Salt River Project (SRP). To help protect the State’s fresh water supplies, the Salt River Project (SRP) developed a set of Sustainability Goals, highlighting the need to increase the use of recycled water to become more water resilient. Action plans include, but are not limited to, reducing total groundwater mining in the State’s AMAs. Within the State’s five AMAs, reclaimed water production is estimated at 140,000 million gallons per year (MGY) of which only 25,000 MGY is used in power generation, the majority going to the Palo Verde Nuclear Generating Station. Because water and energy are inextricably linked, each relying on the other for production through to distribution, the adoption of this untapped potential can facilitate a more water resilient future for SRP. Each SRP station was paired with one to three WRFs within a 25-mile radius. To evaluate potential partnerships, water usage and water quality needs of each station were assessed and compared to discharges from paired WRFs. Water usage data for cooling towers, spanning three years (2017-2019) for each station, was collated from the Energy Information Administration (EIA). Additional water usage and water quality data was obtained directly from each of the stations. Using a variety of sources, data from twelve WRFs were used to estimate potentially available reclaimed water based on volumes of produced treated effluent not already allocated for reuse and were used as the basis to identify and prioritize potential partnerships. Total facility-wide water withdrawals, including groundwater, surface water, and recycled water, for all seven stations averaged 10,000 MGY. Average annual total groundwater withdrawals are approximately 7,600 MG (76%), surface waters 2,100 MG (21%), and recycled water 280 MG (3%). Groundwater withdrawals within the AMAs, used specifically for cooling towers, reaches nearly 3,000 MGY. While the goal of SRP is to reduce groundwater withdrawals within the AMAs by 8 percent (a reduction of 240 MGY), the potential for much greater reductions is possible. Of the seven SRP stations assessed, five were identified as having the potential for reuse opportunities with at least one of the paired WRFs within a 25-mile radius having a supply of reclaimed water that met or exceeded the demand. The analysis indicates, based on distance and volume of supply, that recycled water could augment at least 35 percent of groundwater withdrawals (a reduction of nearly 1,050 MGY) within the AMAs alone. The potential for expanding reuse to augment all freshwater supplies, within and outside of the AMAs, is also possible and should be further investigated. This study was a first step in identifying potential reuse partnerships between SRP and WRFs in Arizona. From this work, a report was provided to SRP and includes the full water usage and water quality assessment of the fleet of generating stations and WRFs, identified gaps in SRP data management and communications and recommendations for improvement, limitations to the study, challenges to reuse in power generation and recommendations to overcome them, and key next steps. In addition, all raw data was transferred to SRP. While there are many considerations for using recycled water in power generation, including water availability and quality; distance and geography between supply and demand; system requirements; and cost and regulatory requirements, the main objective was to provide SRP an overview of the fleet’s total water demands and water footprint to use as a framework to identify priority areas and viable opportunities for potential reuse partnerships with WRFs.
  • Are Bioavailable Nutrients Reliable Predictors of Extracellular Enzyme Activities in Semi-Arid Soils?

    Blankinship, Joseph C.; Muscarella, Chance; Barberán, Albert; Gallery, Rachel E. (The University of Arizona., 2022)
    Because potential extracellular enzyme activities (EEAs) represent microbial investment intonutrient acquisition, they may be sensitive to soil nutrient conditions and land management practices. However, inconsistent relationships between EEA and bioavailable nutrients such as inorganic N and P are generally reported. I therefore asked whether bioavailable nutrient concentrations could serve as a reliable predictor of EEA in semi-arid ecosystems. I sampled six vineyards throughout the state of Arizona, USA, collecting soil samples from within the vineyard itself and outside the area of active management. A suite of soil physicochemical characteristics including nitrate, ammonium, phosphate, and the activities of two N-acquiring [N-acetyl-β- glucosaminidase (NAG) and leucine aminopeptidase (LAP)] and one P-acquiring [phosphatase (PHOS)] EEAs were measured in each sample. I found that concentrations of inorganic N were extremely poor predictors of NAG and LAP activities. Soil phosphate concentrations were similarly poor predictors of PHOS activity. The activities of the two N-acquiring enzymes were not correlated with each other, contrary to my expectations. Additionally, the measured EEAs did not show consistent patterns based on sampling location. These findings lead me to the conclusion that EEAs are unreliable indicators of nutrient limitation or land-use in semi-arid (agro)ecosystems.
  • Inclusive School Climate as a Protective Factor for LGBTQ Youth

    Yoon, Jina; Corcoran, Colleen; Bauman, Sheri; Kirkpatrick, Jennifer (The University of Arizona., 2022)
    Bullying continues to be a significant public health issue disproportionally impacting LGBTQ youth. Bullying is one of many factors contributing to this population’s increased risk for several adverse physical, social, psychological, and academic outcomes. LGBTQ inclusive school practices have been identified as a potential point of prevention and intervention, leading to decreased victimization and increased reporting behaviors. While extant literature has illustrated the impact of individual school policies and practices, more work is needed to understand the cumulative effect of an LGBTQ inclusive school climate. The current study explored the impact of an LGBTQ inclusive school climate, as defined as the presence of an LGBTQ student organization and inclusive dress code, anti-discrimination policy, and anti-bullying policy, on student victimization experiences, reporting behaviors, and adjustment. The study investigated the climates of nine individual schools with a total of 2,571 participants. Results indicated that LGBTQ youth continue to report high levels of victimization and that victimization experiences are associated with poorer adjustment. An LGBTQ inclusive school climate, however, was not found to moderate the relationship between LGBTQ youth victimization and negative adjustment. Total school climate score was found, however, to predict homo/transprejudice attitudes, with more inclusive school climates associated with less prejudice attitudes. This study provided invaluable insights into the experiences of LGBTQ youth and the role of school climate. Future directions for further clarification of the elements of an inclusive school climate to support LGBTQ youth were also provided.
  • Sojourning Mentality, Acculturative Stress, and Mental Health among Chinese International Students and Visiting Scholars in the United States

    Breiger, Ronald; Zeng, Liwen; Martínez, Daniel; Menchik, Daniel; Diaz, Christina (The University of Arizona., 2022)
    This dissertation bridges the literatures on race, migration, and health to highlight the acculturation experiences and related health implications among Chinese immigrants, particularly sojourning Chinese international students in the US. Due to their temporary stay in the recipient society, Chinese students usually demonstrate a sojourning mentality that is characterized by a strong attachment to their home country and a keen desire to return home after fulfilling their migration goals. This mentality appeared more intense during the COVID-19 pandemic when the migration environment (particularly the anti-Chinese racism) featured a heightened level of hostility to sojourning Chinese immigrants in the US. Therefore, this dissertation utilizes data from multiple sources to investigate how sojourning mentality (and possible changes during the pandemic) interplayed with Chinese students’ experiences of acculturation and acculturative stress, and their mental health status. For the first study that comprises my dissertation, I have utilized the nationally representative survey data from the 2002-2003 National Latino and Asian American Study (NLAAS) to investigate the link between acculturation and mental health among Chinese immigrants in the US. Specifically, I have employed weighted OLS regression and binary logistic regression analyses to examine the relationship between acculturative stress and psychological distress among foreign-born Chinese immigrants, and whether such an association persists and varies on the basis of respondents’ levels of ethnic identification (the best proxy measure available for sojourning mentality in the NLAAS). My findings indicate that higher levels of ethnic identification are associated with respondents’ lower levels of psychological distress. However, for respondents who have stayed in the US for over 20 years, higher levels of ethnic identification are associated with greater vulnerability to psychological distress when they encounter acculturative stress simultaneously. For the second study of my dissertation, I designed and conducted a cross-sectional online survey among Chinese international students and visiting scholars currently studying in the US. The goal was to establish and validate a psychometric scale of sojourning mentality. Using convenience and network sampling, I managed to recruit 698 participants, with 643 qualified responses and a completion rate of 80.7%. Using multiple rounds of exploratory factor analyses (EFA) on a convenience sample of 545 adult Chinese international students and visiting scholars studying in the US, I constructed a 24-item measurement scale of sojourning mentality that is composed of 4 factors, including Attachment to Chinese Identity, Motivations to Stay in the Host Society, Preparedness to Return to China, and Motivations to Leave the Host Society. I further assessed the construct validity of this measurement scale by examining its association with three theoretically related concepts, including acculturative strategy, acculturative stress, and depression. This 4-factor solution accounts for over 60% of the total variance and exhibits satisfactory internal reliability and construct validity. This study is original and unprecedented, as it has established and validated the very first psychometric scale of sojourning mentality. Future research is strongly encouraged to apply this scale to other sojourning population(s), using probabilistic sampling. For the concluding study of my dissertation, I employed qualitative data from 59 in-depth interviews with Chinese international students recruited from my online survey in stage 2, in order to investigate their decision about whether to return to China, and to examine how such a decision (and resultant sojourning mentality) can influence and interact with their acculturation in the US during the COVID pandemic. Overall, I find that this population of foreign students demonstrates diverse levels of orientation toward returning to China, including immediate return (“yes, immediately.”), postponed return (“yes, in a few years.”), undecided return (“It depends.”), and refusal to return (“No, I will stay here.”). Except for Chinese visiting scholars who were determined sojourners, a majority of the students constantly develop, negotiate, and readjust their decisions about whether to return, and they do so throughout their entire stay in the US. By further exploring the post-migration experiences of the 55 interviewees who expressed at least some degree of intention to sojourn, I identify consistently and persistently four types or levels of sojourning mentality, including exploratory, pragmatic, disillusioned, and detached sojourning. I find that each mode of sojourning mentality can lead to distinctive acculturation attitudes and acculturative stressors that these students mostly embrace and encounter. These findings, therefore, provide supportive evidence for the call for a measurement scale of sojourning mentality.
  • Do They Support Our Cooperation? Public Support for Cross-Movement Coalitions under Authoritarian Rule

    Schuler, Paul J.; Truong, Mai Thanh; Klar, Samara; Westerland, Chad; Earl, Jennifer; Cyr, Jennifer (The University of Arizona., 2022)
    This dissertation examines the factors that affect public support for coalitions between prodemocracy advocates and policy-based movements, such as land, labor, and environmental movements under authoritarian rule. First, I argue that when the two types of movements actively team up in a coalition to seek significant regime reforms to resolve the policy issues, (1) the policy-based movement’s assignment of causal responsibility for its grievances and (2) the public perception of which component of the coalition-based collective action frame is more dominant may influence public opinion towards the coalition. Using two online survey experiments administered on a sample of 1300 Vietnamese respondents, I find that (1) blame attribution does not influence public attitudes and that (2) the policy frame is perceived to dominate a policy-prodemocracy coalition, which moves support for the coalition to the baseline support for the policy movement. My mediation analysis suggests that this is because policy protesters are perceived to dominate the coalition. Second, I argue that when prodemocracy advocates endorse a policy movement without apparently building a coalition with policy protesters, the public reduces their support for the policy movement. Drawing on an online survey experiment administered to 1080 Vietnamese respondents, I demonstrate that being endorsed by prodemocracy advocates reduces support for protests because prodemocracy endorsements lead to a reduced perception that the protests are legal and a reduced perception that the protests are “moral.” Taken together, the results of the dissertation suggest that public support for a policy-prodemocracy coalition may depend on the visibility of prodemocracy advocates in the coalition. In an active coalition in which policy issues are more dominant and prodemocracy activists are less visible, the public does not oppose the alliance. On the other hand, in a passive coalition where the public perceives that prodemocracy advocates endorse policy protesters without actually cooperating with them, prodemocracy activists may be more visible. This may lead to reduced public support for the coalition and the policy protest.
  • Defining the Nitrogen Requirement for Guayule Growth in a Semi-Hydroponic System and Root Growth of Transplants and Direct-Seed Plants

    Ray, Dennis T.; Evancho, Blase; Ottman, Michael; McCloskey, William (The University of Arizona., 2022)
    Guayule (Parthenium argentatum Gray) is a desert adapted shrub, and a source of domestic natural rubber. Guayule requires fewer production inputs (namely water, fertilizer, and pesticides) to produce economic yields than typical crops grown in the southwestern United States. This is of immense importance due to the recent reduction in access to Colorado River water for irrigation in Central Arizona. Growers are now making decisions to alter crop rotations and fallow large portions of their land. This low water use crop may provide an attractive alternative cropping solution. While guayule has been grown at some level in the US since the early 1900’s there are still many questions around the most economical practices for its production. The first study in this thesis clarifies the role of nitrogen fertilizer in guayule growth and developed a field tool for diagnosing nitrogen deficiency. The second study developed a clearer understanding of the different root systems guayule produces when grown by transplanted seedlings versus direct-seeding into the soil. Together they increase our understanding of how to best grow this crop.
  • Plant-Fungal Symbioses: Climate Change, Applications for Plant Production, and Farmer Education

    Arnold, A. Elizabeth; Colón Carrión, Nicole Marie; Pryor, Barry M.; Orbach, Marc; Tax, Frans; Hu, Jiahuai (The University of Arizona., 2022)
    Climate change is associated with increasing challenges for the wild and agricultural ecosystemson which humans depend. In our most diverse forests and in agricultural lands, rising temperatures, shifts in precipitation regimes, and growing pressure from pathogens and pests represent major challenges that will impact the supply of food, fuel, fiber, and ecosystem services worldwide. Although the effects of climate change on plant communities have been studied previously, their particular effects on plant-microbe symbionts are less understood. Plant symbioses with microbes, especially microscopic fungi, are vital for plant resilience, productivity, and survival in all ecosystems. In my dissertation I examine how climate change impacts aspects of plant-fungal associations, with a focus on two main environments: wild tropical forests, which are storehouses of biodiversity; and agricultural systems, the immediate sources of the plant products we need for human use. Specifically, my work focuses on understanding (1) how hurricane disturbances affect the diversity and composition of fungal symbionts associated with roots and leaves of tropical forest trees, with a focus on Puerto Rico; (2) how fungal symbionts can protect cultivated plants against heat stress and disease under a rapidly warming climate, with a focus on Lactuca sativa, an important crop in Arizona; and (3) how gaps in knowledge about plant pathogens merit attention in areas where tropical and agricultural environments meet, and climate change is felt in all sectors, as in the island of Puerto Rico. In quantifying effects of hurricane damage on fungal symbionts of tropical trees, I used a combination of fieldwork, next-generation sequencing, and statistical approaches to study fungal endophytes (fungi that live within healthy plant tissues without causing disease). I found a significant relationship between foliar endophyte richness and hurricane damage, with evidence that severe damage to forests is associated with decreases in symbiont biodiversity. To understand how such symbionts can impact plant health I transitioned to an economically important cultivated crop. I selected endophytic fungi isolated from Lactuca serriola (prickly lettuce), a weed that grows in hot locations and shows no signs of disease. I then used a series of in vitro and greenhouse experiments to evaluate whether these endophytes could colonize and impact the health of cultivated lettuce (Lactuca sativa) in response to heat stress and disease caused by a pathogen (Fusarium oxysporum f. sp. lactucae, FOL). Bioassay results showed inhibition of FOL by all of the focal endophytes and indicated that they were non-pathogenic to L. sativa. One endophyte enhanced stress-tolerance in L. sativa and significantly reduced disease severity of FOL. This endophyte represents an important focus for future research, as it may have important crop-improvement capacity for cultivated lettuce in our rapidly changing world. Finally, based on my growing interest in Extension and growing threats to agriculture in Puerto Rico due to increases in hurricane activity and pest pressure, I assessed the needs and knowledge of Puerto Rican farmers regarding the control and management of pests and pathogens in the field, with the goal of customizing educational workshops that fit the needs of farmers in the island. With Institutional Review Board approval, my study employed a questionnaire to improve understanding of the main problems faced on farms in Puerto Rico. I developed a plant pathology lesson plan that introduces basic concepts in plant pathology and disease management. This enhances Puerto Rican farmers’ knowledge and adaptive capacity, increases accessible education to underrepresented farming communities, and provides extension educators and interested institutions with open access to educational materials – all increasingly important in a world marked by climate change.
  • Investigating Late-Stage Explosive Eruptions on the Volcanic Rises of Mars and Venus

    Carter, Lynn M.; Ganesh, Indujaa; McGuire, Luke A.; McEwen, Alfred S.; Andrews-Hanna, Jeff C.; Holt, Jack W. (The University of Arizona., 2022)
    Spacecraft missions to other planets in the inner solar system have led to the identification of evidence for explosive or pyroclastic volcanism in the past. The timing and distribution of explosive activity in the inner solar system has implications for interior magmatic processes, crustal evolution and interior composition, and atmospheric evolution. Investigating occurrences of pyroclastic activity is therefore necessary to develop a comprehensive understanding of a planetary interior and evolution. In this dissertation, we present studies of past explosive activity on the topographic rises of Mars and Venus. Our objectives include characterizing the spatial extent of pyroclastic deposits (on Mars), investigating the emplacement dynamics of pyroclastic deposits (on Venus), and determining the physical properties and structure of pyroclastic deposits (on Venus). We address these objectives primarily using radar remote sensing and theoretical modeling. An introduction to terrestrial and planetary volcanism, and the significance of explosive volcanism is presented in Chapter 1. We also introduce planetary radar instruments and observations in this chapter. In Chapter 2, we discuss late-stage explosive activity in the caldera of Arsia Mons, one of the largest shield volcanoes on Mars. We show how orbital sounding radar observations, together with Bayesian inversion techniques, can be used to map the subsurface and determine the distribution of buried pyroclastic units. In Chapters 3 and 4, we focus on potentially recent explosive activity on the shields and coronae of Venus. Several radar bright deposits in the highlands of Venus have been interpreted as pyroclastic flow deposits. We present a multi-pronged approach to investigate the emplacement and physical structure of these deposits. In Chapter 3, we develop a numerical model for pyroclastic flow transport and deposition on Venus. By comparing the results from the model with orbital observations, we narrow down possible pyroclastic eruption conditions. In Chapter 4, we analyze the scattered and emitted radiation at microwave wavelengths from these deposits to place constraints on the physical properties and shallow-stratigraphy. Lastly, we summarize our findings and discuss avenues for further research in Chapter 5.
  • Optical Readout Systems for Optomechanical Inertial Sensors

    Guzman, Felipe; Anderson, Brian P.; Zhang, Yanqi; Wilson, Dalziel (The University of Arizona., 2022)
    The advancement of a compact optomechanical inertial sensor with ultra-high acceleration sensitivity in the sub-Hz regime requires its optical readout system to have a small footprint, low noise floor, and large dynamic range. In this dissertation, three optical readout systems are designed based on common-mode heterodyne interferometry, including a compact interferometer with off-the-shelf optical components, a customized quasi-monolithic interferometer assembly, and a two-wavelength fiberbased interferometer. A benchtop prototype of each configuration is developed and tested in the lab. Preliminary measurements show that all three instruments reached single-digit picometer level sensitivity above 1 Hz and sub-nanometer level sensitivity in the millihertz regime. Investigations are conducted regarding common noise sources in the low-frequency regime, such as laser frequency noises and temperature fluctuations. The corresponding post-processing algorithms are developed to mitigate these noise effects and improve the instrument sensitivity. Furthermore, the optical readout systems are integrated with a tunable optomechanical inertial sensor design to provide a sub-picometer level of sensitivity and large bandwidth capable of measuring seismic activities. Details of the feedback damping system in this inertial sensor are designed with a novel cascaded cooling system to improve the cooling efficiency with less radiation pressure actuation.
  • Quality Improvement Through Covid-19 Intubation Checklist Implementation

    Hoch, Kristie; Rios, Michael Paul; Torabi, Sarah; Herring, Christopher; LaRoche, Jennifer (The University of Arizona., 2022)
    Purpose: The purpose of this project was to increase awareness and airway provider confidence levels with use of a COVID-19 adult intubation checklist at a rural medical facility in northern Arizona. Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus responsible for COVID-19, has infected over 1.9 million people within the state of Arizona. Some of these COVID-19 patients will develop acute respiratory failure with profound hypoxemia, multi-organ failure, and often may require intubation with invasive mechanical ventilation needs. Airway management of COVID-19 patients may be improved through use of a facility-specific COVID-19 adult intubation checklist. New strategies are needed to decrease the transmission of COVID-19, thus educating airway providers on current recommended checklist use may be critical for providers, healthcare workers, medical organizations, and the surrounding communities. Methods: Through an educational presentation, the recommendations, benefits, and potential for quality improvements with utilization of a COVID-19 adult intubation checklist was presented to project participants. Surveys were conducted before and after the presentation. The survey information was used to identify increases in checklist awareness, airway provider confidence levels, and future intent to use a specialized COVID-19 intubation checklist. Results: Four certified registered nurse anesthetists participated in this project representing a 57% response rate during recruitment. All four participants completed the PowerPoint presentation and both surveys. Survey data displayed reported increases in airway provider confidence levels and likelihood to use a site-specific COVID-19 intubation checklist. 100% (n=4) of participants agreed on improved communication and team performance benefits with use of a properly implemented checklist. Conclusions: Through creating awareness of the current recommendations for intubation of COVID-19 patients, airway provider confidence levels can be increased with utilization of a site-specific intubation checklist.
  • Increasing Suicide Awareness in Nurse Anesthesiology

    Hoch, Kristie; Partida, Elizabeth Kaye; Elam, Charles R., IV; Prettyman, Allen V. (The University of Arizona., 2022)
    Purpose: This Doctor of Nursing Practice (DNP) project aims to increase suicide and gatekeeper awareness among the University of Arizona nurse anesthesiology program clinical site coordinators through an educational presentation. Community-based gatekeeper training is one of the most widely used suicide prevention strategies, educating laypersons on how to recognize, approach, and support a person at risk of suicide. Background: Anesthesia providers have a greater risk of suicide than any other healthcare specialty, with certified registered nurse anesthetists (CRNAs) and resident registered nurse anesthetists (RRNAs) being significantly impacted. For example, 41.7% of RRNAs have reported symptoms of depression, and 21.2% reported suicidal ideation during their anesthesia education. Methods: This educational intervention quality improvement (QI) project aims to increase suicide awareness among the nurse anesthesiology clinical coordinators of the University of Arizona. The volunteer participants will be sent a previously recorded educational session and an accompanying PowerPoint via email. After viewing the educational session, participants will access the link embedded in the email to direct them to an anonymous retrospective pretest assessment survey. Results: Nine clinical coordinators participated in this QI project. A statistically significant improvement was seen overall and across all three survey subscales based on the Gatekeeper Behavior Scale. Also, all participants had found the educational intervention to be useful. Conclusions: Nurse anesthesiology clinical coordinator gatekeeper training effectively provides knowledge about RRNA suicide risks and warning signs, increases suicide prevention skills, and improves self-efficacy. The relevance of this topic continues to emerge with the untoward effects of COVID-19 and the addition of the practice doctorate in nurse anesthesiology education.
  • Testing Whether Rock Dams Cause Rapid Recharge

    Ferre, Ty; Hsieh, Diana Florence; McIntosh, Jennifer; Meixner, Thomas (The University of Arizona., 2022)
    Groundwater resources are under stress due to increased pumping observed in an increasingly arid American southwest. When more water is pumped out than is recharged, this results in over pumping which causes drying wells, land fissures, and land subsidence. Therefore, it is important to look for ways in which to conserve and replenish our aquifers. One possible mitigation strategy is the use of rock dams, which slow the flow of water and promote infiltration beneath ephemeral streams. Studies have shown that rock dams can improve riparian health, however, it is unclear whether these structures can cause recharge of groundwater over short timescales (months). The sooner that aquifers can be recharged, the sooner aquifers can begin to recover, drawdown can be mitigated, and land subsidence and fissures can be avoided. Our hypothesis was that rock dams could cause rapid recharge (recharge within 3-months) and that mounding of the water table could be an indication that rapid recharge was occuring. To test this hypothesis, water samples were collected during the 2021 summer monsoon season and analyzed for major anions and cations, stable water isotopes (δ18O and δD), and tritium (3H). The water chemistry and isotope data did not show any evidence of rapid recharge. Using HYDRUS-1D, different soil textures and streamflow durations were modeled to determine the theoretical conditions that would allow for rapid recharge. Based on the modeling results, we found that only soils that contained little to no clay would allow for recharge on the scale of months. However, our models used several simplifying assumptions and considering real-world complexities, we would not expect to see recharge on the scale of months, but rather years. To determine true recharge rates of rock dams, future monitoring systems could do tritium testing on the scale of years and/or install additional sensors (pressure or water content) in the subsurface to track infiltration rates on a longer timescale.
  • Ecology of Invasion: Potential for Parasite Spillover in Abert’s Squirrels (Sciurus Aberti) and Endangered Mt. Graham Red Squirrels (Tamiasciurus Fremonti Grahamensis)

    Koprowski, John L.; Jones, Deandra; Stock, Patricia; Merrick, Melissa (The University of Arizona., 2022)
    Invasive species are among the leading global threats to native wildlife and are a factor in the decline of 42% of threatened and endangered species. Invasive species can influence ecosystem health through parasite loads that they introduce during establishment in new areas. In the 1940s, Abert’s squirrels (Sciurus aberti) were introduced to the Pinaleño Mountains in southeastern Arizona where they now co-occur with endemic endangered Mount Graham red squirrels (Tamiasciurus fremonti grahamensis). Parasite loads between invaders and imperiled endemic species are poorly understood, including S. aberti and T. f. grahamensis; where we identified and quantified parasites in this important system. We hypothesized that spillover of parasites occurred between S. aberti and T. f. grahamensis. We also hypothesized that presence/absence of parasites might be affected by host-linked factors and extrinsic factors. Genetic analyses through PCR amplification revealed two species of helminths from single nematode DNA: Citellinema sp. and Trypanoxyuris (Rodentoxyuris) sp. Our results suggest the potential for spillover of Trypanoxyuris (Rodentoxyuris) sp. between S. aberti and T. f. grahamensis. The following ectoparasites were encountered in Abert’s squirrels: Opisodasys robustus, Anomiopsyllus sp., and Neohaematoinnus sciurinus. The following ectoparasites were encountered in Mt. Graham red squirrels: Orchopeas caeden and a species of mite from the Glycyphagidae family. Body mass influenced presence/absence of endoparasites and males are more likely to have presence of ectoparasites than females in Abert’s squirrels. Enhanced insight into possible parasite transmission routes and the role that parasites play in biological invasion can offer a better understanding of all factors that place species at risk of extinction. Our data highlight the importance of developing future management and conservation strategies for similarly threatened or endangered species.
  • The Influence of Fraternal Membership on Bisexual, Pansexual, and Polysexual Members' Sexual Identity Development

    Nicolazzo, Z; Lemerand, Steve Michael; Kraus, Amanda; Marquez Kiyama, Judy (The University of Arizona., 2022)
    Researchers have established that fraternity environments are rife with homophobia, heterosexism, and hypermasculinity, which diminish queer members’ experiences, force them to develop coping strategies, and limit opportunities for them to explore or develop their sexual identities. While numerous studies explored the experiences of queer members in fraternities, no study in the extant literature specifically explored the unique experiences of nonmonosexual (e.g., bisexual, pansexual, polysexual) members. All studies either neglected the nonmonosexual community or grouped them with other queer identities and assumed they have an indistinctive experience. Scholars have called upon student affairs practitioners and scholars to address monosexism in higher education, and the present study explored this gap in the literature. Using a narrative inquiry qualitative design, I engaged in semi-structured conversations with 8 nonmonosexual fraternity alumni, representing 8 undergraduate institutions and 7 inter/national fraternities. The conversations lasted 40-85-minutes and were recorded via Zoom. I conducted a thematic data analysis based on three-cycle coding and I made sense of three prevailing themes. First, participants’ fraternal membership facilitated liberatory firsts, including their first sense of self-acceptance, first time finding queer community, and/or first time acting upon their sexual identity externally. Second, participants became aware of and were forced to cope with the hostile environments in their fraternities by performing a masculine or heterosexual identity, distancing themselves from hypermasculinity, homophobia, and heterosexism, and/or splitting queerness from hostility. Third, participants addressed monosexism and biphobia in their fraternities by internally grappling with their identities and the performance thereof, responding head-on through education, and/or disengaging from the fight. A broader narrative of the present study is that fraternities are sites of multiplicity and complexity; the same environments and experiences that foster liberation for pan/bi/poly members may also re/create the negative implications of hetero/monosexism. Thus, the influence of fraternal membership is neither all good, nor all bad, but rather, multiple and complex. I conclude with five recommendations for practice: 1) resist monosexism as strongly as we resist heterosexism, 2) resist capitalist monosexism, 3) reimagine authenticity and queer student development, 4) deconstruct binaries, and 5) recognize the multiplicity and complexity of lived experience.
  • Educating Flesh: Blackness and the (Primal) Scene of Campus Insurrection at San Francisco State College (1968-69)

    Nicolazzo, Z; Brown, Zachary Ryan; Carter, Derrais A.; Geary, Adam M. (The University of Arizona., 2022)
    Highlighting the relationship between the racial slavery in the formation of U.S. colleges and universities and the archive of Black student revolt, this dissertation examines one of the longest and most violent Black student strikes in the history of postsecondary education–the San Francisco State College strike in 1968-1969. Rather than deconstruct the strike for a central meaning or produce a (counter)narrative history, this dissertation argues that the politics of Black student revolutionaries during this strike radicalizes constructions of the modern educational subject and invites a reconsideration of Black educational subjectivity. Working towards the notion of the captive subject of education as a theory and method for reading the guerrilla tactics of Black students during the five-month siege of campus to elucidate these claims, this dissertation overreads reading the actions of Black student revolutionaries in solidarity with the political, affective, and psychic conditions that engender slave insurrection to suggest an alternative theory of the Black educational subject that emphasizes the psychopolitics of student protest.

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