The UA Master's Theses Collection provides open access to masters theses and reports produced at the University of Arizona, including theses submitted online from 2005-present and theses from 1895-2005 that were digitized from microfilm and print holdings, in addition to master's reports from the College of Architecture, Planning and Landscape Architecture from 1966 onwards. The collection includes hundreds of titles not available in ProQuest.

We have digitized the entire backfile of master's theses and doctoral dissertations that have been submitted to the University of Arizona Libraries - since 1895! If you can't find the item you want in the repository and would like to check its digitization status, please contact us.

The UA Master's Theses collection is not comprehensive; master's theses from 1993-2015 were only received and archived by the UA Library and ProQuest if the student chose to pay the optional archiving fee. The Library does not have copies of many master's theses submitted during this time period. Some academic departments may keep copies of theses submitted to their programs. Colleges and departments wishing to archive master's theses not available in the University Libraries are encouraged to contact us at repository@u.library.arizona.edu.


Please refer to the Dissertations and Theses in the UA Libraries guide for more details about UA Theses and Dissertations, and to find materials that are not available online. Email repository@u.library.arizona.edu with your questions about UA Theses and Dissertations.

Recent Submissions

  • Urbanization and Grazing Impact on Mesquite Phyllosphere and Soil Microbial Communities

    Barberán, Albert; Cleavenger, Sydney Paige; Blankinship, Joseph; Babst-Kostecka, Alicja (The University of Arizona., 2022)
    Dryland degradation driven by human activities, particularly associated with urban and grazing land use types, has been shown to result in an overall loss of biodiversity above and below the soil surface. The modification of microbial community dynamics by these degrading processes can result in ecosystem changes that could potentially lead to the proliferation of invasive species, changes in biogeochemical cycling, and injury soil and plant health. This study attempts to investigate the impacts of urban and grazing land use types on the soil and phyllosphere microbiome associated with velvet mesquite (Prosopis velutina). The goal of this research was to analyze differences in the above and belowground microbiomes that are specific to urban or grazing land use types to potentially identify microbial trends associated with land degrading processes. Soil and phyllosphere samples were collected from three land use types including natural, urban, and grazing (light and heavy pressures). Soil bacterial/archaeal communities did not demonstrate significant differences across locations, but soil fungal richness and diversity was significantly lower in urban locations. However, urban phyllosphere exhibited greater average microbial richness and Shannon diversity than natural or grazing locations. Heavy grazing pressure resulted in lower soil fungal diversity, but fungal richness was not significantly different between grazing pressures. Inferred microbial functional group proportions showed that urban soils had the lowest average proportion of nitrogen fixers and cellulolytic microorganisms, but the greatest average proportion of fungal plant pathogens. Light grazing pressure exhibited a significantly greater proportion of soil arbuscular mycorrhizal fungi. The phyllosphere of urban locations had the greatest average proportion of nitrogen fixers and locations with heavy grazing pressure demonstrated the greatest proportion of phyllosphere fungal plant pathogens and cellulolytic microorganisms.
  • Hypoxia-Induced Centrosome Loss in Epithelial Cells

    Rogers, Gregory C.; Loertscher, Emily; Cress, Anne E.; Ellis, Nathan (The University of Arizona., 2022)
    Centrosome loss has recently been reported as a phenotype of prostate cancer. Hypoxia, an environmental condition seen commonly in prostate cancer, can cause centrosome loss in the immortalized prostate epithelial cell line, RWPE1. Little is known about hypoxia-induced centrosome loss, including how commonly it occurs in other cell types and the mechanism behind centrosome loss. This thesis further characterizes hypoxia-induced centrosome loss as seen in RWPE1 cells as well as in two other epithelial cell lines, MCF10A and HaCaT. Hypoxia-induced centrosome loss is affected by cell density and is reversible upon return to oxygen in some cell lines. Disassembly of centrosomes in hypoxia may happen through a two-step process, first with the removal of pericentriolar material and then this the disassembly of centrioles.
  • Arterial Spin Labeling MRI To Determine Effects of Transcranial Magnetic Stimulation on Cerebral Blood Flow in Patients Diagnosed With Mild Cognitive Impairment

    Chen, Nan-kuei; Bracamonte, Sierra Varina; Chou, Ying-hui; Trouard, Ted (The University of Arizona., 2022)
    Mild cognitive impairment (MCI) is a term used to describe adults who have not crossed the threshold into being diagnosed with progressive dementia, typically Alzheimer’s, but show obvious signs of cognitive impairment1. Recent studies have determined that reduced cerebral blood flow (CBF) has effects on the pathophysiology of Alzheimer Disease (AD)2 and can be one of the early symptoms before any obvious signs of cognitive impairment, but the study of hyper/hypoperfusion patterns in AD are still controversial with many differing opinions and not enough research. Transcranial magnetic stimulation (TMS) has been an important tool used as a therapeutic device for cognitive disorders, like depression, and has begun to be used as a treatment for other cognitive impairments, like MCI or AD. TMS has also been known to have the ability to affect perfusion (increasing or decreasing it) based on the style of TMS and the strength of the applied magnetic field. To determine the effects of transcranial magnetic stimulation on cerebral blood flow, perfusion changes can be detected using arterial spin labeling (ASL), a type of MRI modality. In this study, 11 subjects underwent testing for MCI and were split into groups of those diagnosed as having MCI and those who were diagnosed as cognitively normal (CN). All subjects completed sessions of transcranial magnetic stimulation therapy. ASL MRI images were obtained before and after the sessions and region of interest statistical analyses were carried out to determine if TMS affects CBF differently in patients diagnosed with MCI. Subjects with MCI showed statistically significant differences in CBF in certain regions compared to the CN group and suggest that TMS may alter CBF in areas affected by hypoperfusion in patients diagnosed with MCI and AD.
  • The New Absurdists: Elements of the Absurd in New Russian Drama

    Lucey, Colleen; Bedoy, Andrew Martin; Leafgren, John; Jens, Ben (The University of Arizona., 2022)
    This thesis examines the importance of the absurd in Russia's New Drama movement. Three different plays are analyzed: Russian National Postal Service (1998) by Oleg Bogaev, Vodka, Fucking, and Television (2006) by Maksim Kurochkin, and Man from Podolsk (2017) by Dimitrii Danilov. Each work is used to examine a different aspect of the absurd in the Russian context. Using these plays, which are some of the more prominent works of New Drama, the thesis demonstrates how the socio-political circumstances affected playwriting in the post-Soviet period. The goal is to show how upheaval, confusion, and changing circumstances bore out in the theater scene through a push towards Absurdism in playwriting. The three plays are analyzed through in-depth close reading that connects New Drama to the Theater of the Absurd and Albert Camus' philosophical writings. Ultimately, the thesis shows that what ties New Drama together is not an overemphasis on documentary style (as many scholars have argued), but a distinct reworking of Absurdism to express Russian reality.
  • Evaluating Gill Net Standardization and Electrofishing Boat Operation Techniques in Arizona Reservoirs

    Bonar, Scott A.; Grant, Joshua; Bogan, Michael; Reinthal, Peter (The University of Arizona., 2022)
    I conducted a paired-gear comparison study in large standing warmwater reservoirs in Arizona during fall 2020 and spring 2021 between Arizona Game and Fish Department (AZGFD) standard gill net (Arizona net) and the American Fisheries Society (AFS) standard gill net (AFS net). The Arizona net and AFS net share the same height, hanging ratio, and twine sizes but differ in length, number of panels, and panel bar-mesh sizes. Adopting a national standard gear like the AFS gill net would allow AZGFD to use a uniform net methodology across the state, give the ability to compare data with other states that use the AFS standards, and allow for larger scale analyses. In five large lakes (Alamo, Apache, Bartlett, Pleasant, and Roosevelt) I investigated how each net was different or similar with regards to species diversity, pick and pull times, catch per unit effort (CPUE), and length structure. I also set out to create conversion factors to allow AZGFD to convert data from the Arizona net to be compared with the AFS net. I found that the AFS net caught the same species as the Arizona net, however, the Arizona net caught three additional species than the AFS net. The AFS net averaged about six and a half minutes faster to pick and pull per net than the Arizona net. For CPUE, the AFS net was higher for some species while the Arizona net was higher for others. Overall the Arizona net CPUE was greater than the AFS net. In both cases, the difference in fish caught per net was often minimal. For length frequencies, each net caught the same length ranges but had some differences in proportions of fish sizes. Lastly, I successfully developed CPUE conversion factors, although, fit of the model differed by species. Fisheries managers should recognize that each net does have biases with regards to using one net over the other for management goals. Further paired-gear testing between Arizona and AFS gill nets will add useful information to reliably help AZGFD convert to the AFS standard.Coincidingly in the spring of 2021, I conducted a boat electrofishing study comparing three boat maneuvers and pedal operations for completing transect surveys. In the same five large reservoirs, I sampled using a continuous 600 s pedal-down transect parallel to shore (continuous parallel); an intermittent 10 s on 10 s off 600 s pedal-down transect parallel to shore (intermittent parallel); and 600 s pedal down transect with multiple arcs applying power only when incoming to shore/cover (arc intermittent) and compared their total time and distance per transect, CPUE of fish per hour and per m, and length frequencies. I found on average, continuous parallel took the least amount of time while arc intermittent took the least amount of distance to complete a 600 s pedal-down transect. For CPUE (fish/hr) there was evidence of differences for three species being higher in arc intermittent than in the other methods, which were similar, but no differences among any of the methods for five other species. For CPUE (fish/m) there was strong evidence for differences among multiple methods being higher than others for all species but two. Lastly, I found that each method caught the same size ranges of fish, however, some differences in proportions of sizes in some species were evident. Overall, each of the three electrofishing approaches tested should work well for documenting reservoir fish populations in general, but certain species and sizes may be best quantified using just one of the three approaches.
  • Whether the Different Learning Environments Influence Students’ Learning Motivation

    Pope, Elizabeth; Yang, Junzhe; Marx, Ronald; Tullis, Jonathan (The University of Arizona., 2022)
    University students’ courses transitioned from in-person learning to online learning during COVID-19 in 2020. In 2021, many universities offered online courses and in-person courses for students. This study aimed to explore whether students’ learning motivation was related to their different learning environments (online learning and in-person learning) and whether students in these two kinds of learning types had different degrees of learning motivation. Thus, the present study examined students’ intrinsic motivation, extrinsic motivation, and amotivation in two different learning environments (online learning and in-person learning). The data were collected from 141 undergraduate students. The findings exhibited that university students’ learning motivation (intrinsic motivation, extrinsic motivation, and amotivation) was not related to learning environment (online learning and in-person learning) during COVID-19. Furthermore, this study presented some suggestions for improving students’ learning motivation.
  • High Speed Grating Shear Interferometry for Fast Steering Mirror Characterization

    Hart, Michael; Colon, Nicolas Iokepa; Kim, Daewook; Milster, Thomas D. (The University of Arizona., 2022)
    Several terrestrial and aerospace applications require the ability to track a Fast-Steering Mirror’s (FSM) high velocity slew rates with microradian positional resolution. Using theoretical analysis and Monte Carlo simulations, the Fast Linescan Grating Shear Interferometer (FLGSI) was designed to meet this demand with commercial off-the-shelf (COTS) parts. The primary goal of this thesis was to demonstrate that the calibrated FLGSI could constantly track the relative FSM position while the FSM was driven with sinusoidal and square electrical waveforms. The angular magnification, the grating period, and the source wavelength affected the measurement resolution of the FLGSI. The FLGSI design had better than -0.5 waves of coma and less than 0.75 waves of spherical aberration (at 632.8 nm) for the ±4 mrad system FOV. With a photon noise model corrected by measured results, the FLGSI propagated uncertainty was less than 9.5 µrad when measuring the FSM angular position with FSM velocities below 1.5 rad/s, and when measuring a stationary FSM, the FLGSI could measure FSM movements as small as 49.22 nrad (twice the FLGSI measurement uncertainty). The OIM 202 was modeled to estimate the mirror velocity, and design experiments to test the FLGSI measurement capabilities. The secondary goal of this thesis was to measure the OIM 202 movement properties with the FLGSI and compare them with the modeled and manufacturer reported properties. The FLGSI, with a framerate faster than 40 kHz, accurately tracked the FSM position when the FSM was moving at rates slower than 1.1761 ± 0.58 rad/s. The FLGSI measured the FSM X-axis settle time to be 9.98 ms with a pointing accuracy of ±1.38 µrad and the FSM Y axis settle time to be 6.69 ms with a pointing accuracy of ±0.94 µrad. The settle time was slightly slower, and the pointing accuracy was slightly worse than quoted manufacturing specifications.
  • The Phonology and Morphology of Siriano A Grammar Sketch

    de Lima Silva, Wilson; Ni, Tianyi; Harley, Heidi; Henderson, Robert; Wedel, Andrew (The University of Arizona., 2021)
    This thesis presents a linguistic description of the phonology and morphology of SIRIANO, an endangered Amazonian language traditionally spoken in the Vaupés River region of northwest Amazon, in Brazil and Colombia. There is little extant documentation of Siriano; therefore, the description is primarily based on the data gathered by the thesis chair Dr. Wilson de Lima Silva.Siriano is a typical Eastern Tukanoan language in terms of its typological characteristics. It has a relatively small phonemic inventory, and most of the phonemes, both vowels, and consonants have nasalized counterparts. The syllable structure is very simple. The glottal stop and fricative are phonetically realized in a careful speech to modify the syllable structure. Siriano has a two-tone system, with high and low tones. They can be lexical tones, but some of them are not and change accordingly with the morphological processes. Stress is also shown to interact with tone patterns. Nasal spreading is very commonly seen, but the oral inherent morphemes block this phonological process. It has plentiful nominal categories and noun-related suffixes, with simple morphological processes. Verbs require tense, aspect, modality, and evidential marking in the form of suffix attachment. Overt evidential marking is used to distinguish the present and distant past tense.
  • Regulation of the Endogenous Blood-Brain Barrier Transporter Organic Anion Transporting Polypeptide 1A4 (Oatp1a4) by Testosterone in an Immortalized Mouse Brain Endothelial Cell Line (bEnd.3)

    Ronaldson, Patrick T.; Nava, Raul; Falk, Torsten; Lynch, Ronald M. (The University of Arizona., 2021)
    The biochemical and physical properties of the blood-brain barrier (BBB) are known to regulate drug delivery to the central nervous system (CNS), making it incredibly challenging to treat neurological diseases. A viable strategy may be to target organic anion transporting polypeptides (OATPs in humans; Oatps in rodents), transporters that facilitate blood-to-brain drug uptake. Over the past several years, our laboratory has studied the involvement of OATPs/Oatps in the BBB transport of drugs that are effective in treatment of neurological pathologies such as cerebral hypoxia/reoxygenation stress and ischemic stroke. Using male and female Sprague-Dawley rats, we have shown that Oatp1a4, the primary drug transporting Oatp isoform at the rodent BBB, is critical for brain delivery of 3-hydroxy-3-methylglutarylcoenzyme A (HMG-CoA) reductase inhibitors (i.e., statins). More recently, we have shown that Oatp1a4 functional expression is higher at the BBB in female Sprague-Dawley rats as compared to their male counterparts. Interestingly, this work also showed that Oatp1a4 protein expression and transport activity in brain micro-vessels from castrated male rats was the same as in female control rats or in ovariectomized females. This observation pointed towards a role for male gonadal sex hormones in the regulation of Oatp1a4 at the BBB. Therefore, we sought to determine the effect of testosterone on Oatp1a4 protein expression using a mouse brain micro-vessel endothelial cell line (bEND.3). Specifically, we studied the effect of testosterone in normoxic cells and in cells subjected to oxygen/glucose deprivation (OGD), an in vitro condition relevant to ischemic stroke. In normoxic (i.e., control) bEND.3 cultures, testosterone increased Oatp1a4 protein expression in a dose-dependent manner. In contrast, testosterone reduced Oatp1a4 protein expression in bEND.3 cells subjected to 8 h OGD but had no effect in these cultured mouse brain endothelial cells after 8 h OGD/24 h reoxygenation (i.e., OGD/R). Interestingly, testosterone treatment increased expression of the androgen receptor under both OGD and OGD/R conditions. Overall, these data provide the first evidence for differential regulation of Oatp1a4 protein expression by testosterone under normoxic, OGD, and OGD/R conditions. Further studies are required to evaluate the implications of these findings on transport of Oatp1a4 substrates (i.e., statins) and to determine the molecular machinery involved in altered Oatp1a4 expression in endothelial cells following exposure to testosterone.
  • Enemies and Brothers: Nationalism in Russian Official Discourse Regarding Crimea

    Klimanova, Liudmila; Donahoe, Maria; Leafgren, John; Willerton, John P. (The University of Arizona., 2021)
    This study focuses on nationalist language in Russian official discourse (political and media discourse) regarding Crimea. The discourse reveals two major trends: anti-Ukrainian sentiment and pro-Russian sentiment. While several studies outline the official narrative and document examples of nationalist language, no study analyzes this language through the lens of nationalist theory. This study aims to 1) outline the language and sentiments in Russian official discourse, 2) place this language within its social/historical context, and 3) explain the emotive power of such language through nationalist theory and Critical Discourse Analysis (CDA). The researcher used Eric Hobsbawm’s instrumentalist theory of nationalism and Anthony Smith’s ethno-symbolist theory of nationalism, as well as Norman Fairclough’s and Teun van Dijk’s frameworks of CDA. The research suggests that through ideologically contested language, the discourse presents a narrative of the Ukrainian regime as a threat to Russians in Crimea and highlights Russia’s duty to defend its historic homeland.
  • Printing Clay: Design Optimization for 3D Printing Sustainable and High-Performance Housing

    Ida, Aletheia; Puppos, Andrew; Dickinson, Susannah; Musters, Paulus (The University of Arizona., 2021)
    The changing climate, a precarious economy, and political turmoil have left countless people homeless throughout the world. As more people are displaced by climate change and other issues, the number of people who lack adequate housing in the world will continue to grow. Due to the enormous impact of architecture and construction on the environment, a method for housing these people that is climate-conscious must be developed. Whether housing is needed for migrants and refugees arriving at international borders, or for citizens displaced within their own homelands by climate disasters, the key to housing these people is creating an adaptable method of quickly constructing shelter. 3D printing offers a fast and efficient solution which can utilize responsive design to minimize the environmental impact, while keeping costs low for unhoused people who are struggling financially. Utilizing parametric design techniques can lead to design strategies that optimize a house for the local climate conditions and reduce both the energy used to keep occupants comfortable and the resources extracted from the local environment. 3D printing can also begin to move from using concrete materials with a high carbon footprint to locally source materials like adobe made from soil extracted from the site, to achieve the lowest possible environmental impact. This research begins by analyzing the thermal performance of 3D printed samples with varying infill values to determine the best print parameters for good thermal performance in hot climates. Building on this, a strategy for creating responsive home designs that use this knowledge to modify the geometry of a structure according to its local climate conditions. These buildings are algorithmically optimized for the climates where they are needed to address housing needs, and moving forward, will be tested at larger scales with local clay materials.
  • The Effect of Urban Geometry on Microclimate and Outdoor Thermal Comfort (Downtown Tucson, Arizona as case study)

    Dickinson, Susannah R.; Jundus, Ashwaq (The University of Arizona., 2021)
    As climate change continues to increase, the way we are planning and building our cities needs to be reexamined, especially in places that have been affected by it. One of these regions is the southwest region of the United States which is considered one of the most affected regions by climate change behind Alaska according to the National Climate Assessment (2013). The area has been witnessing prolonged heat waves, drought, and wildfires. This thesis aims to study one of the primary urban locations in Tucson, Arizona, Congress Street, in terms of how the urban geometry affects the microclimate and thus affects the outdoor thermal comfort level. It also compares how accurate simulation weather tools are to real-world field data.
  • ROS Formation in Ischemia Reperfusion During Intervention of Coronary Artery Blockage

    Chen, Qin; Emile, Shannon; Streicher, John; Navratilova, Edita (The University of Arizona., 2021)
    Reactive oxygen species (ROS) formation during myocardial ischemia is a leading cause of tissue injury. Ischemic reperfusion injury is defined as cellular damage caused by the restoration of blood flow to the once ischemic tissues. Throughout the ischemic period of significantly reduced blood flow and depleted ATP storage, ROS production is heightened, which is further enhanced during reperfusion. The main contributors to ROS generation during ischemic reperfusion are damaged mitochondria and activation of xanthine oxidase (XO) or nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Increased superoxide production results in many cellular, biochemical and molecular reactions, including damage of macromolecules or cell death. Although reperfusion via a coronary artery bypass graft (CABG) surgery or a percutaneous coronary intervention (PCI), is effective to restore the blood flow, cure the symptoms and revive the patients, these non-invasive and invasive procedures can also induce ROS production, thus increasing the incidence of cardiomyocyte cell death. This literature review explains the consequences of the CABG and PCI procedures for ROS production and the mechanistic insight that causes cellular dysfunction and death.
  • Whitefly Resistance Management: Time and Space Refugia in Cross-Commodity Systems of Arizona and California

    Ellsworth, Peter C.; Dayoob, Naomi; Palumbo, John; Carrière, Yves (The University of Arizona., 2021)
    Insecticides are central for control of whiteflies (Bemisia argentifolii = B. tabaci MEAM1); however, this pest has frequently evolved resistances. Chemical controls are available for whiteflies in Arizona and California’s cross-commodity agricultural communities. To curtail chemical resistances in whiteflies, resistance management programs are a necessary component of an Integrated Pest Management (IPM) plan. Diversifying practices and not over relying on available chemistries allows us to actively manage refugia. Available section-level application records of whitefly control chemistries from 2013-2017 were used in developing insights into local and regional usage patterns and the availability of temporal and spatial refuges to whitefly populations. Populations collected from cotton were tested for susceptibility to seven chemistries: acetamiprid, imidacloprid, buprofezin, cyantraniliprole, fenpropathrin, pyriproxyfen, and spiromesifen. Temporal and spatial refugia for six whitefly modes of action (MoA) were calculated over a region-wide and community level associated with collected populations. Mortality data were compared with pesticide usage patterns over five look-back periods preceding the date of collection. We produced validated partition models that predicted whitefly susceptibilities based on the availability of spatial or temporal refugia in ca. 23 sq km communities for each mode of action. In our analyses there were variations in model performance with some performing relatively well, while others did not. Further refinement may be needed to optimize look-back periods for better model performance. Insights gained should support development of practical decision tools that could be used by growers to better partition chemistry through space and time in their local communities.
  • The Composition and Diversity of Volatile Organic Compounds (VOCs) From Leaf Litter in the Biosphere 2 Tropical Rainforest

    U'Ren, Jana M.; Crocker, Lia Noel; Meredith, Laura; Hurwitz, Bonnie (The University of Arizona., 2021)
    Background: Volatile Organic Compounds (VOCs) are organic compounds with high vapor pressure at room temperature released by plants, bacteria, archaea, fungi, and protists. Plants and microbes can produce VOCs as a means of communication (i.e., signaling and species interactions) or as a mechanism to ameliorate abiotic stress (e.g., isoprene with high temperatures). The majority of microbial VOC (mVOC) studies have focused on volatiles produced from soils, but recent evidence suggests that leaf litter can have greater VOC production, microbial biomass, and respiration rates adjacent soil. However, it is difficult to differentiate plant VOCs from mVOCs and identify the different mechanisms driving their release into the atmosphere. Thus, as part of an ecosystem-scale project at the Biosphere 2 Tropical Rainforest (B2 TRF) that addressed the impact of drought on VOCs from soil and living leaves (i.e., Biosphere 2 Water, Atmosphere, and Life Dynamics: B2 WALD), I performed a 10-day VOC experiment of leaf litter to: (i) quantify and identify VOCs produced by Clitoria leaf litter in B2TRF; (ii) examine the impact of moisture on litter VOC flux; and (iii) determine whether flux patterns can be used to distinguish plant VOCs and mVOCs. Methods: Leaf litter was collected from five individuals of Clitoria fairchildiana distributed across the B2 TRF. VOCs were continuously measured over a 10-day period from four replicate chambers and a control chamber using proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). To examine the impact of moisture on VOC fluxes, leaf litter was wet after seven days to simulate a rainfall event. VOCs were identified by comparing each mass to a reference database and flux calculations were performed to examine change in VOC abundance over time, after accounting for the control. Results: In total, 304 VOCs were identified across all four replicate chambers. Wetting altered the flux of 35% of litter VOCs. Among VOCs emitted after wetting, 72 decreased to pre-wetting levels within 24 hours, while 25 sustained higher production with increased moisture. Conclusions: Leaf litter represents a significant source of VOCs yet even with high resolution real-time data it is difficult to differentiate plant-derived VOCs from mVOCs due to shared metabolic pathways, as well as limited information on mVOCs. In addition, although I hypothesized that wetting would stimulate mVOC production, strong fluxes of VOCs after wetting were likely plant-derived VOCs whose release from the leaf surface was amplified by Henry’s law. Future work is needed to identify mVOCs from microbial cultures and link to leaf-level measurements.
  • The Role of Prolactin in the Sex Differences of Pruritus

    Porreca, Frank; Chow, Michele Moon; Navratilova, Edita; Bear, David (The University of Arizona., 2021)
    Background: Mechanisms promoting itch sensations may be sexually dimorphic. Previous studies have shown that application of pruritogens elicits a greater activation of brain structures that are believed to be involved in the central processing of itch in healthy women when compared to men. In addition, women with chronic pruritus experience more itch attacks and scratch lesions and during pregnancy, many women develop a dramatic increase in itch that may reduce their quality of life. However, whether the observed greater prevalence of certain itch conditions in women is based on sexually dimorphic mechanisms of itch is unknown. Here, we investigated whether the PRL/PRLR signaling system can activate, or sensitize, pruritoceptors (itch-selective neurons) as a possible mechanism that may contribute to the higher prevalence of certain itch conditions in women. Methods: We used an established cheek model of itch to first observe the effects of local PRL on the induction of acute itch development by performing a single intradermal injection of PRL to the right facial cheek of CD1 (ICR) mice. Immediately after the injections, the behaviors were recorded for thirty-minutes. We next observed whether the pretreatment of local PRL could enhance acute pruritus that is induced by the known pruritogens: chloroquine phosphate or histamine. For these experiments, we performed a single intradermal injection of PRL to the right facial cheek of CD1 (ICR) mice and one-hour afterwards we administered either chloroquine or histamine at the same site. The behaviors were also recorded for thirty-minutes. Since stress is known to increase circulating levels of PRL, we determined if repeated stress would sensitize the animals to chloroquine-induced itch. For these experiments, we subjected ICR mice to restraint stress (RS) for three-consecutive days for two-hours. On the last day of RS induction (Day 3), we performed a single intradermal injection of chloroquine or the control to the right facial cheek and recorded the behaviors afterwards for thirty-minutes. To determine if repeated stress produces a priming effect, we waited fifteen days (Day 15) after the first day of RS and induced acute pruritus and recorded behavior. Next, to confirm the results of the Day 15 experiment, we performed the induction of acute pruritus on the seventeenth day (Day 17) after the first day of RS induction and recorded behavior. Results: We found that local PRL injections do not induce acute itch development in either male or female mice. Additionally, pretreatment with PRL did not enhance or potentiate acute pruritus induced by chloroquine or histamine in either sex. Repeated stress, which increases circulating levels of PRL, does not induce acute itch development nor did it enhance chloroquine-induced itch in either sex. In contrast, stress decreased chloroquine-induced itch in both sexes. Finally, stress induced priming did not promote acute itch behaviors in female and male mice. Conclusion: The PRL/PRLR signaling system neither activated nor sensitized pruritoceptors. Therefore, the PRL/PRLR signaling system does not explain the increased prevalence of itch disorders in females.
  • Climate Warming Driven Changes in the Cryosphere and Their Impact on Groundwater-Surface Water Interactions in the Heihe River Basin

    Condon, Laura E.; Triplett, Amanda; Ferre, Paul; Meixner, Thomas (The University of Arizona., 2021)
    The Heihe River Basin in Northwestern China depends heavily on manmade and natural storage like surface reservoirs, rivers, and groundwater for economic and environmental functions. The Qilian Mountain cryosphere in the upper Heihe River Basin is integral to recharging these storage supplies. Climate change driven shifts in high elevation water storage are expected to have significant impacts on water supply in the Heihe River Basin. To examine the impacts of these shifts, we built a hydrologic model using ParFlow-CLM of the middle basin, which encompasses over 90% of water usage. Using this model, we ran 4 simulations over the period of 2001 to 2011. These simulations are meant to model impacts of streamflow changes due to the loss of glaciers and advanced permafrost degradation on the middle basin. First, we ran a baseline scenario which uses unaltered streamflow data of all gaged streams entering the middle from the upper basin as input. Then, we ran three scenarios one with a 15% streamflow reduction in the thawing season (April to October) to represent the loss of glacial contribution to streamflow. The next with a 50% baseflow increase year-round to represent the response to permafrost degradation. The last scenario applies both perturbations. Results show enhanced groundwater discharge when flow is reduced, and infiltration when flow is increased, with a diminishing role of the subsurface over time and more of the streamflow change passing through. Seasonal trends show different behaviors in groundwater-surface water partitioning due to glacial loss and permafrost degradation. Additionally, flow changes due to permafrost degradation are expected to outweigh those resulting from glacier loss. Ultimately, this analysis can be used to examine the cascading impact of climate change in the cryosphere on the resilience of water resources in arid basins downstream of mountain ranges globally.
  • Calibration and Commissioning of a Mach 5 Ludwieg Tube at the University of Arizona

    Craig, Alex; Bearden, Kyle; Little, Jesse; Threadgill, James (The University of Arizona., 2021)
    Calibration, commissioning, and design features of a new Mach 5 Ludwieg Tube(LT5) at the University of Arizona are discussed. In addition, a tunnel shake-down has been completed and is examined. Diaphragm characterization for operation of LT5 has been completed and is reviewed. An experimental investigation into the Mach-number uniformity and free-stream noise levels using a Pitot rake at a range of unit Reynolds numbers (Re′) at multiple spanwise and streamwise positions has been performed. The wind tunnel has been shown to have a Mach number of 4.82 with variance less than 0.8% (and less than 0.5% at most streamwise positions). Throughout the experimental collection, streamwise positions of Pitot sensors range from -601.2 mm upstream of the nozzle exit plane to 256.3 mm downstream of the nozzle exit plane. Spanwise positions of Pitot sensors range from centerline to within 7.62 mm (0.3 in) of the tunnel wall. Mach number and free-stream noise profiles have been determined in both streamwise and spanwise directions. Calculating the thickness of the boundary-layer as the location where M is 99% of the free-stream value (δ99), a central core flow region has been determined at three locations. Within this central core, the average free-stream noise level (based on Pitot measurements) is shown to be less than 1.2% at an intermediate Reynolds number with some regions locally dropping below 1.0%. Additionally, as Re′ is increased, the free-stream noise level consistently decreases. Further, within both the boundary-layer and central core flow region, spectral content of the free stream has been characterized to estimate the power spectral density (PSD).
  • An Analysis of the Impact of Small Dams on River Fragmentation and Regulation in the Contiguous United States

    Condon, Laura E.; Spinti, Rachel; Meixner, Thomas; Troch, Peter A. (The University of Arizona., 2021)
    Small dams account for 96% of the more than 50,000 anthropogenic structures on rivers in the United States (US). While dams are critical pieces of infrastructure to human systems, they have contributed to the decline of river connectivity by regulating streamflow dynamics and fragmenting river networks, which threatens the health of freshwater ecosystems. Prior studies of river regulation and fragmentation demonstrated how large dams have impacted river networks. However, small dams account for most structures and 48% of reservoir storage in the US. This study is the first to evaluate the impact of small dams on the river network of the contiguous US (CONUS). We map 51,923 structures onto the US river network to evaluate the current and historical development of fragmentation and regulation. Our results illustrate similar patterns of widespread regulation and fragmentation particularly along major river networks as previous global studies focusing on large dams. The addition of 49,990 small dams in our analysis reveals the full extent of regulation and fragmentation in CONUS. Analysis of small dams highlights the extent to which regulation has expanded into headwater systems over time and their compounding impact on total river regulation. Today, nearly every watershed in the US has high levels of anthropogenic fragmentation and spatial trends have been reversed with the highest fragment densities now occurring in humid regions which can support more structures. In these locations with the largest change in fragment density, small dams account for over 70% of the change.
  • The Influence of COVID-19 and Virtual Learning on the PCK Development of Arizona Preservice SBAE Teachers

    Rice, Amber; Schoeffling, Alexandra Lynn; Rice, Amber; Molina, Quintin; Mars, Mathew (The University of Arizona., 2021)
    The central research question that guided this study was: what is the influence of COVID-19 restrictions and modifications on the pedagogical content knowledge (PCK) development of the UArizona school-based agricultural education (SBAE) preservice teachers in agriculture, food, and natural resources content? This research was conducted using a single case study design of one preservice teacher cohort over the spring 2021 semester. Semi-structured interviews were conducted for all five preservice teachers, two university instructors, one teaching assistant, and five supervising practitioners throughout the student teaching experience. There were seven major themes that emerged from the data: it was primarily a classroom teaching experience, student teachers were prepared well in curriculum development, a lack of experimentation and problem solving in teaching, a lack of relationship building with students and professionals, student teachers were more protected from failure due to the COVID-19 environment, this cohort exhibited resiliency, and overall student teachers are prepared to teach. These themes support future research on PCK development through online and hybrid modalities while still incorporating early field experiences (EFE)’s and student teaching in-person. Further exploration on this cohort while in their first job post student teaching can provide information on the development and application of their PCK outside of the context of COVID-19. Recommendations for practice include implementing multiple EFE’s with deep reflection and the creation of one semesters worth of curriculum prior to student teaching during teacher preparation. Additionally, it is recommended supervising practitioners and university instructors maintain a balance of constructive criticism and positive feedback throughout the student teaching process regardless of current circumstances. Keywords: COVID-19; virtual learning, PCK development, preservice teachers, school-based agricultural education

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