Now showing items 1-20 of 15204

    • Flow Structure and Heat Transfer Characterization of a Blunt-Fin-Induced Shock-Wave/Laminar Boundary-Layer Interaction

      Little, Jesse C.; Castro Maldonado, Jorge Alberto; Craig, Stuart A.; Wernz, Stefan (The University of Arizona., 2021)
      An experimental investigation of a blunt-fin-induced shock-wave/laminar boundary-layer interaction (SBLI) has been conducted at a nominal Mach number of 4.The experimental data is supplemented by computational results from Reynolds-averaged Navier Stokes computations provided by Raytheon Missiles & Defense.Two blunt fins with a leading-edge diameter of 9.525 mm (3/8”) and sweep angles of 0 and 45 degrees were tested on a flat plate with unit Reynolds number 4.3×10^6 m−1 (Re_x= 2.7×10^5). The unswept fin produces significant separation extending x/D ≈ −5.5 upstream of the fin leading edge. Mach number contours indicate two horseshoe vortices wrapping around the unswept fin base. The swept fin SBLI features are subdued in comparison, but qualitatively similar, with evidence of horseshoe vortices also present. Temperature sensitive paint (TSP) was employed to investigate the near-wall flow structure and estimate surface heat flux. Prominent features include various reattachment lines associated with vortices in the separated region, as well as shock-shock interactions and shear-layer impingement on the fin leading edge. Increasing the sweep angle altered the flow topology considerably, including the location and magnitude of maximum heat flux. The surface distribution of Stanton numbers are derived, demonstrating complex interactions with a rich set of flow physics to be investigated in future work. Amongst other findings, the influence of sweep has a moderate impact on peak heat transfers, with Stanton numbers reaching 0.022 and 0.035 for the swept and unswept fins respectively.
    • Dysregulation, Deficiency, and Virus Associated Pathologies Related to the Complement System

      Proffitt, James; Wilson, Justin; Buchanan, Dylon Cole; Ahmad, Nafees (The University of Arizona., 2021)
      The complement system is a frontline component of the immune response against invading pathogens. When functioning properly, it can help with the successful elimination of pathogens through opsonization, membrane attack complex formation, and cell signaling. When dysfunction or deficiency arises, these processes can be hindered and afflicted persons can be at increased risk of certain diseases due to the lack of complement protein production. These diseases can include systemic lupus erythematosus, glomerulonephritis, and increased risk of bacterial infections (de Cordoba et al., 2012). Several viruses have developed the capability of either evading or utilizing the complement system to their advantage. The emergence of SARS-CoV-2 has led to questions as to how this virus interacts with the complement system. While there is still much that is unknown, many of the pathologies caused by SARS-CoV-2 infection have a complement-induced component. For instance, patients diagnosed with severe COVID-19 disease have been noted to have elevated C3a and membrane attack complex components leading to lung, vasculature, and kidney damage (Java et al., 2020; Santiesteban-Lores et al., 2021). Additionally, the intracellular complement system, termed the complosome, is important for the regulation of immune cells by signaling homeostatic CD4+ T-cell survival through stimulating the mTOR pathway and for aiding in the immune response by activating the CD46 complement receptor (Liszewski et al., 2013; Arbore et al., 2017).
    • Human Cytomegalovirus Infection in Endothelial Cells Induces the Secretory Autophagy Pathway for Egress

      Goodrum, Felicia; Molina, Belen; Wilson, Jean; Purdy, John; Campos, Samuel (The University of Arizona., 2021)
      Human cytomegalovirus (HCMV) is a β-herpesvirus that establishes a lifelong infectionwith the potential to infect multiple cell types, including vascular endothelial cells. While infection in fibroblasts is well-characterized, much remains to be understood about key differences in the infection of other cell types. Endothelial cells support a slow and chronic infection while contributing to the spread of the virus to distal organs. However, the cellular and molecular determinants of HCMV infection in endothelial cells remain poorly understood. Both infected endothelial cells and fibroblasts incorporate viral material, like virions and dense bodies, into a multivesicular body (MVB)-like vesicle. However, these vesicles have distinct biogenesis in each cell type. Virus-containing vesicles in fibroblasts are classical MVBs marked by CD63 and LBPA. However, characterization of the vesicles in endothelial cells showed that cis-Golgi (GM130), lysosomal-associated membrane protein- 1 (LAMP1) proteins are on the limiting membrane of the virus-induced vesicles, and autophagy maker LC3B is on the membranes of intraluminal vesicles. These markers are commonly associated with the secretory autophagy pathway. Moreover, the vesicles in endothelial cells lack CD63 and LBPA. These results suggest that the virus-containing vesicles in infected endothelial cells may traffic through the secretory autophagy pathway. Our findings support this suggestion in that we have found differences in protein levels of Rab8A and Rab8B, two proteins that distinguish degradative autophagy from secretory autophagy, in infected endothelial cells. These findings suggest that HCMV induces the secretory autophagy pathway in endothelial cells possibly for egress. Furthermore, HCMV has evolved mechanisms to co-opt host trafficking pathways for transport, virion maturation, and egress among other functions. The viral protein UL135 has been shown to have a role in the rearrangement of membrane trafficking, and incorporation of virus material into MVB-like vesicles. We investigated the role of UL135 in the biogenesis of the virus-induced vesicles and its involvement in the induction of the secretory autophagy pathway during infection using immunoblotting for both viral proteins and well-characterized markers of secretory and degradative autophagy. We found that, in the absence of pUL135, Rab8A, LC3B, and P62 are increased, suggesting that pUL135 is involved in the decrease of lysosomal activity thus the decrease in degradation. This may suggest that UL135 may be involved in the biogenesis of the LAMP-1, GM130, LC3B positive vesicles and possibly give preference to the secretory autophagy pathway when incorporating virus material into the vesicles for egress. This work provides novel insights into the diversity of mechanisms by which HCMV hijacks membrane trafficking in different cell types and will reveal cell type-dependent roles for secretory autophagy in HCMV infection.
    • Mechanisms of Blood Brain Barrier Dysfunction in Stroke: A Therapeutic Opportunity

      Ronaldson, Patrick T.; Sami, Ayman; Vanderah, Todd W.; Lochhead, Jeffrey J. (The University of Arizona., 2021)
      Stroke is the 5th leading cause of death in the United States according to the 2019 CDC Mortality Data. There are ~795,000 new incidences of stroke each year, and this prevalence is increasing in correlation with the aging population of the United States [159]. At 4-6 hours post-stroke, there is breakdown of the blood brain barrier (BBB). The BBB is comprised of brain microvascular endothelial cells that line the cerebral microvasculature. Functionally, the BBB provides a physical and biochemical barrier between the brain and the systemic circulation. Barrier properties of the BBB are provided by tight junctions and transporters that control selective passage of substances into the brain. During stroke, tight junction integrity and transporter expression is considerably altered, leading to significant leakage of substances from the systemic circulation. Of particular significance, BBB dysfunction also results in edema and swelling in the brain. Following the leak is a generalized immune response that exacerbates the ischemic insult in the brain [236]. Neurons start to die because of the inflammation. If this edema is not controlled within the first 24 hours, cognitive damage is permanent, and death may result [160]. Thus, preservation of the BBB during ischemic injury is critical to maintaining the health of the individual and preventing BBB dysfunction. Due to the limited therapeutic options available, it is critical to discover novel strategies for treatment of stroke and preservation of BBB integrity. In this dissertation, stroke pathophysiology is reviewed with an emphasis on BBB dysfunction. Research methods that can be used to identify new stroke therapeutics that have vascular protective properties will also be highlighted. This discussion will focus on statins, a class of therapeutics that are commonly administered to stroke patients due to their known ability to improve post-stroke neurological outcomes.
    • Assessment of Various Precipitation Products in Capturing Atmospheric Rivers and their Performance as a Function of Near-Surface Conditions

      Behrangi, Ali; Arabzadeh, Alireza; Dong, Xiquan; Gupta, Hoshin V. (The University of Arizona., 2021)
      Accurate estimation of precipitation is critical for hydrology, study of the Earth system, and various water-related applications. This study investigates the performance of various precipitation products in two challenging areas. First, their performance in capturing Atmospheric rivers (ARs) precipitation and extreme events related to ARs and, second, precipitation estimation over cold surfaces with snow and ice on the surface. The first chapter of our study comprises investigation of AR‐related precipitation using 18 years (2001–2018) of globally gridded AR locations. AR precipitation features are explored regionally and seasonally using remote sensing (Integrated Multi‐satellitE Retrievals for GPM version 6 [IMERG V6], daily Global Precipitation Climatology Project version 1.3 [GPCP V1.3], bias‐adjusted CPC Morphing Technique version 1 [CMORPH V1], Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks [PERSIANN‐CDR]), and reanalysis (MERRA‐2 and ECMWF Reanalysis 5th Generation [ERA5]) precipitation products. The second chapter includes assessment of IMERG’s various products (IMERG products include precipitation estimates from infrared (IR), combined PMW, and their combination) with respect to near-surface wet-bulb temperature (Tw), precipitation intensity, and surface type (i.e., with and without snow and ice on the surface) over the CONUS and using Stage-IV product as reference precipitation.The main results include: (1) Based on global AR-related precipitation analysis: most of the world (except the tropics) experience more intense precipitation from AR‐related events compared to non‐AR events. It was found that the degree of consistency between reanalysis and satellite‐based products is highly regionally dependent, partly due to the uneven distribution of in situ measurements. There is a better agreement among the products over the tropics than in higher latitudes. The largest inconsistencies occur over the Southern Ocean where IMERG shows the highest percentage of contribution of ARs to total precipitation and extreme events and consequently the highest deviation from other products used in this study. It is shown that, overall, pairs of IMERG/CMORPH and GPCP/PERSIANN‐CDR have higher spatial correlations globally, which is expected given the similarities in their retrieval methods. (2) Based on investigation of various products of IMERG for precipitation retrieval over surfaces with and without snow and ice cover: PMW products generally have higher skills than IR over snow- and ice-free surfaces. Over snow and ice surfaces (1) PMW products (except AMSR-2) show a higher correlation coefficient than IR, (2) IR and PMW precipitation products tend to overestimate precipitation, but at colder temperatures (e.g., Tw<-10oC) PMW products tend to underestimate and IR product continues to show large overestimations, and (3) PMW sensors show higher overall skill in detecting precipitation occurrence, but not necessarily at very cold Tw. The results suggest that the current approach of IMERG (i.e., replacing PMW with IR precipitation estimates over snow- and ice-surfaces) may need to be revised.
    • Network Analysis of Biomedical Data Using REACH Natural Language Processing

      Yao, Guang; Peri, Sateesh; Ellis, Nathan; Merchant, Nirav (The University of Arizona., 2021)
      One of the core features of scientific work is reading and researching literature. Facing an unknown disease, beginning a new research project, or writing a paper to present your own research data are all good examples of why someone would run a wide literature search. However, it is difficult to stay up to date with the cutting edge of scientific research. A more recent approach that exceeds the limits of traditional manual research lies in automated literature analysis using natural language processing (NLP), something which is particularly relevant in complex biomedical research. NLP permits more rapid access to the information contained in scientific databases and may help to drastically increase the reproducibility of literature searches, allowing researchers to process all documents for a definite result. Network analysis techniques can be used to analyze the information extracted from literature, which often comes in the form of relationships between various biomedical entities. We used the REACH NLP tool to read 1.2 million papers in PubMed to extract mentions of biologically-relevant molecules and their relationship/interaction with other molecules. We then created an application - Visualizing Entities and Relationships in Text (VERIT), that allows users to generate network visualizations by querying the database we generated, which contains relationships between chemicals, proteins, genes, and phenotypes that were extracted by running REACH.
    • Adaptive Multiscalar Design Approach for Urban Dust Storms

      Ida, Aletheia; Modrek, Anahita; Dickinson, Susannah; Dimond, Kirk (The University of Arizona., 2021)
      In the context of the 21st century, which identifies anthropocentrism as a dominant reason for environmental impacts, a consensus is emerging for thinking critically about adaptation and developing necessary actions in response to emerging socio-ecological realities. Continuous processes of urbanization are constantly impacting natural environments, which are deeply interrelated with the aggravation of cumulative environmental, economic, and social problems. This combination results in a profound ecosystem crisis, including climate change, at the epicenter of which are cities and, inevitably, architecture. The natural and urban environments are undergoing a systemic change driven primarily by the evolving processes in culture, science, industry, and commerce. As a result, the architecture discipline seeks to overcome its own preconceptions and adapt to these enhanced understandings of ecological relationships. Therefore, this research focuses on developing a design solution in response to air pollution in arid regions, specifically in Nogales, Mexico. Air pollution is a macro-scale problem that is caused mainly by human activities. If designers integrate human agency with architectural design strategies, we might begin to adapt positively to climate crises like air pollution while increasing our awareness about the impacts of human activities. This research proposes a wearable weather station on a scale of a human body equipped with climate sensors. The wearable weather station or human dust shelter will act like an urban element accessible to people when they face harmful air quality. The design process mainly focuses on environmental data like air movement pattern, the impact of sun and radiation on different surfaces, Sand and Dust Storm (SDS) behavior. The Plant and the adaptation systems in nature also play prominent role as a source of inspiration for learning the morphology and adaptation strategies. The evaluation of these natural systems for commonalities and differences through methodical and rigorous comparison of their flows and compositions reveals that adaptive systems have a strong relationship with context. Similar systems in varying contexts have different performance characteristics and different ways of responding because of the complex set of parameters within the context of evolutionary design. These adaptative systems in nature respond to a complex challenge, showing inherent traits that allow for adaptation to climate change, indicating that both material selection and design strategies need to be based on the specific ecological realities of a given context.
    • Deterministic Optimization for Short-Term Scheduling of Thin Seam Deposits With Autonomous Technologies

      Tenorio, Victor; Palomino, Orlando; Kemeny, John; Momayez, Moe; Vivas, Raul Ernesto (The University of Arizona., 2021)
      The extraction of thin seam mineral deposits requires to overcome several challenges due to the level of accuracy needed in order to cut layers of reduced thickness, which has a direct impact on the reserves, dilution control, and blending, therefore in the final economic results of the operation. This becomes more critical when seams are less than 40 cm. thick. A strategy based on the deployment of smart equipment, which includes autonomous Scrapers coupled with high precision Continuous Surfer Mining (CSM) machines, drones for surveying, and modern programming tools, provides a range of multiple scenarios of scheduled sequences, tailored to satisfying Processing Plant requirements. This proposed combination increases the reserve, diminishes the dilution, and improves the long-term present value of the mine. Case studies are presented with a test of the production system, a schedule algorithm, a short-term sequence code in Python, and the results for optimization using actual field data.
    • “A New Form, a New Shape, and a New History” Revolt and Reformation in Sixteenth Century Vienna, 1519–1524

      Lotz-Heumann, Ute; Plummer, Beth; Messinger, Dean; Milliman, Paul (The University of Arizona., 2021)
      In 1519, after the death of Emperor Maximilian, the citizens of Vienna revolted against the emperor’s regency government and seized control of the city. This uprising soon expanded to the aristocratic estates, who joined forces with the urban rebels to challenge the authority of the Habsburgs. At the same time, Reformation ideas, texts, and preachers were entering the city and it was during these years of tumult that the nascent evangelical community in Vienna was born. This thesis examines events in Vienna during a six-year period from 1519 to 1524, exploring the ways in which three distinct lines of conflict- urban, dynastic, and religious- unraveled and intersected during this time of revolt and reformation. Highlighting the fluctuating nature of conflict and negotiation, the polycentric social organization of the city, and the formation and dissolution of insurgent coalitions, this thesis demonstrates how the intensification of preexisting conflicts during this upheaval helped shape the courses and outcomes of these conflicts. Drawing on a variety of archival and published sources from in and around Vienna, I argue that this six-year period of revolt and reformation marks a distinct shift in the history of the city, witnessing a transformation of Vienna’s political, social, and spiritual landscapes. While the defeat of the Viennese revolt meant the abolition of the city’s medieval autonomy and greater monarchical oversight in the city, the fluid and unstable situation created by the revolt allowed for the early and enduring growth of an evangelical Vienna.
    • National Socialist and Allied Perspectives in Photographic Documentation of Art Looting and Restitution

      Romano, Irene B.; Kowgios, Taylor Lu; Cuneo, Pia; Ivey, Paul (The University of Arizona., 2021)
      Conducted on a scale unseen before in history, the Nazi art looting operation set a new precedent for art theft that significantly altered the world’s approach to art protection and restitution in the aftermath of war. Documenting their successes, Nazi art looting agencies like the ERR utilized photography to capture evidence of their activities and of the quality of the artworks they had acquired, ultimately to assert their relevance and justify their existence to the Führer. Similarly, during their efforts to rescue and restitute looted artworks, Allied powers photographed their recovery operation both in the field and at collecting points. This study looks at two Nazi photographic archives documenting the art looting operations: the ERR “Hitler Albums” and the Koblenz Album (Bundesarchiv B 323-311), and Allied photographs of the “Monuments Men’s” active art recovery and restitution efforts at Neuschwanstein Castle and other repositories and at the Munich Central Collecting Point. Comparing the composition of these photographs also reveals similarities in Nazi and Allied methodologies in photographically documenting art looting and recovery, suggesting a shared aesthetic approach in asserting their opposing ideologies. A comparative analysis of their corresponding motivations revealed that the Nazi photographs functioned as semi-private, documentary images; the Allied photos, while also documentary in nature, exhibited greater immediate propagandistic potential. While both the Nazis and the Allies utilized public propaganda in WWII, their photographs of looted artwork occupy a much more complex position as documentary and propagandistic. Both Nazi and Allied photographs were also used as documentary evidence at the end of WWII and still serve today as the basis for provenance research in tracking the history of particular works of art and their owners in the Nazi period. To conclude, this thesis also utilizes these images to trace the provenance of a select few paintings that appear across the Nazi and Allied photographs to illustrate the continued life of the artworks. The Nazis and the Allies both employed photography to dictate the narrative of their respective art operations.
    • Elucidating the Mechanism Behind Altered Retinal Dynamics in Age-Related Macular Degeneration

      Marty, Michael; Norris, Carolanne Elise; Brown, Michael; Charest, Pascale; Aspinwall, Craig (The University of Arizona., 2021)
      Age-related macular degeneration (AMD) is among the leading causes of blindness in the western hemisphere, with approximately 30% of people over 60 years old showing symptoms. AMD is characterized by a significant lowering in the zinc concentration in the eye, the formation of dense pockets of highly oxidized lipid particles called drusen in the retinal pigment epithelial (RPE) cells, and altered capability of the RPE cells to regenerate retinal. However, it is unclear how changes in the oxidative state of the lipids and lower zinc concentrations alter rhodopsin photodynamics. The activity of rhodopsin is dependent on the receptor’s lipid environment, with changes in activity occurring with alterations in membrane curvature, thickness, and fluidity. Malfunction of rhodopsin has been linked to multiple eye disorders that cause visual impairment and blindness, including AMD. Much remains unknown about the effect of specific rhodopsin-lipid interactions and how zinc works to stabilize the receptor. To elucidate these effects on rhodopsin stability, we will perform trials to investigate lipid binding and the effects of bulk layer properties on rhodopsin activation. Furthermore, zinc titrations will be performed at varying concentrations to determine how zinc works to stabilize the receptor.
    • Holographic Curved Waveguide Combiner for HUD/AR

      Blanche, Pierre-Alexandre; Draper, Craig Thomas; Peyghambarian, Nasser N.; Takashima, Yuzuru (The University of Arizona., 2021)
      This thesis contains efforts toward head up display and augmented reality devices using combiners comprised of holographic optical elements on waveguides.Holographic optical elements couple image bearing light beyond total internal reflection conditions within a planar waveguide. The pupil is expanded in 2 dimensions while magnifying the image to produce a head up display with smaller form factor and large field of view over an expanded eye box [1]. Aberration in the form of image duplication is seen in pupil replicating waveguide combiners which were examined and realized to be from the conditions of the internally propagating light. The internally propagating light should be collimated, and a solution is proposed for multiple depths of field to be projected into the viewer’s field of view free from aberration [2]. A method is presented for image propagation through a curved waveguide combiner with pupil replication. The insertion holographic optical element imposes astigmatic power to mitigate propagation aberrations. An extraction holographic optical element outcouples the image over an expanded eye box [3].
    • Hydrogeomorphic Recovery and Temporal Changes in Rainfall Thresholds for Debris Flows Following Wildfire

      McGuire, Luke A.; Hoch, Olivia J.; Youberg, Ann M.; Pelletier, Jon D. (The University of Arizona., 2021)
      Wildfire-induced changes to soil and vegetation promote runoff-generated debris flows in steep watersheds. Debris flows are commonly observed the first wet season following a wildfire, but it is not clear how long the elevated threat of debris flows persists and why debris-flow potential changes in recovering burned areas. This work quantifies how rainfall intensity-duration (ID) thresholds for debris-flow initiation change with time since burning and provides a mechanistic explanation for these changes. We constrained a hydrologic model using field and remote sensing measurements of soil infiltration capacity and vegetation cover as well as hydrologic monitoring data of flood and debris-flow activity. We applied this model to estimate rainfall ID thresholds for debris-flow initiation within three burned areas in the southwestern United States over a post-fire recovery period of 3-4 years. Modeling suggests thresholds are lowest immediately following the fire (below a 1-year recurrence interval storm) and increase with time such that a 10- to 25-year recurrence interval storm would be required to generate a debris flow after 3 years of recovery. Modeled changes in rainfall ID thresholds can be attributed to increases in soil infiltration capacity, canopy interception, hydraulic roughness, and D50 grain size of sediment entrained in an incipient debris flow. The importance of each of these factors varied between the three sites. Results improve our ability to assess temporal changes in post-fire debris-flow potential, highlight how site-specific factors may alter the persistence of post-fire debris-flow hazards, and provide additional constraints on the timescale of geomorphic recovery following wildfire.
    • The Effect of Age-Related Hearing Loss on Perception of Age-Related Dysphonia

      Samlan, Robin; Turner, Melanie; Story, Brad; Bunton, Kate (The University of Arizona., 2021)
      The purpose of this study was to investigate the impact of different degrees of sensory and metabolic-sensory hearing loss on the perception of breathiness, roughness, and strain in aging voices. Four voices identified as normal, breathy, rough/strained, and rough by an expert panel were filtered through the HELPSV2 (Sensimetrics Corporation, Gloucester, MA) hearing loss simulator to create seven distinct hearing patterns per sample. Descriptive acoustic analysis was conducted to examine differences in spectrograms, long-term average spectra (LTAS) and smoothed cepstral peak prominence (CPPS) across voice and hearing loss profiles. Twenty naïve listeners judged the voice quality of each of 28 unique samples on a visual analog scale anchored with the labels “terrible voice quality” and “excellent voice quality.” Data were analyzed using a General Linear Mixed Model (GLMM) and post-hoc comparisons of significant findings. We did not find significant differences in perceptual ratings across any degree of sensory or metabolic-sensory hearing loss for breathy, rough/strained, or rough voices. Metabolic-sensory hearing loss resulted in significantly poorer perceived voice quality than sensory hearing loss for the normal voice, although degree of hearing loss did not significantly impact ratings. These findings provide preliminary evidence that metabolic-sensory age-related hearing loss may distort perception of voice quality, potentially due to a relative reduction in amplitude of harmonic energy in the sample. Future research with larger listener pools is required to further investigate these relationships.
    • Zinc Management and Salt Tolerance of Pecan in Arid Regions

      Walworth, James L.; Smith, Cyrus; Blankinship, Joseph C.; Heerema, Richard J. (The University of Arizona., 2021)
      In the alkaline, calcareous soils common to the southwest zinc reacts with hydroxyl and carbonate groups forming compounds of low solubility, reducing its plant availability, and making soil application of zinc oxide (ZnO) or zinc sulfate (ZnSO4) impractical. Therefore, foliar application of zinc in southwestern pecan orchards is common practice. Fertigation with zinc-ethylenediaminetetraacetic acid (Zn-EDTA) is a possible alternative that has shown positive results in alkaline, calcareous soils. However, many growers fertigating their orchards with Zn-EDTA are still using supplemental zinc foliar sprays due to lack of confidence that soil applied Zn-EDTA can supply enough zinc to the trees. We conducted an experiment to determine if the application of foliar zinc sprays to ‘Wichita’ pecan trees already receiving zinc in the form of Zn-EDTA through fertigation would increase photosynthesis rates. We applied zinc sulfate monohydrate (ZnSO4·H2O), ZnSO4·H2O + Urea Ammonium Nitrate (UAN), Zn-EDTA, water alone, and water + UAN to seven ‘Wichita’ pecans growing in alkaline, calcareous soil in San Simon, AZ. Applications were made twice in 2018 and twice in 2019, Zn-EDTA was applied only in 2019. Photosynthesis measurements were taken approximately two to four weeks following each application. Mid-day stem water potential was also measured to verify that water stress was not limiting photosynthesis. Our results showed that photosynthesis rates were not increased by the application of supplemental foliar zinc sprays in trees fertigated with Zn-EDTA with mean leaf zinc concentrations of untreated leaves in the range of 16-21 mg·kg-1. We concluded that photosynthesis was not zinc limited and that no additional benefit was conferred with regard to photosynthesis from the application of supplemental foliar zinc sprays.Another problem for pecan growers in the southwest is high salt content in the soil. Very little experimentation has been conducted to determine pecan response to saline-sodic conditions. To contribute to this research, we performed an experiment with seven rootstock pecan seedlings grown in alkaline, calcareous, saline-sodic soil at the Safford Agricultural Center in Safford, AZ. The seedlings were chosen from different geographic regions. While we only have knowledge of the maternal genetics of the seedlings which were grown from open-pollinated seed, we hypothesized that seedlings with origins in regions with lower precipitation would be more tolerant of the experimental conditions than those from regions with higher precipitation. It was determined that leaf sodium concentration was more strongly correlated with salt injury in the plants than chlorine. Leaf potassium:sodium (K:Na) ratio was strongly correlated with resistance to salt injury, tree growth rates, and vigor. In support of our hypothesis we found the maternal parentage of the most tolerant seedlings in our experiment was ‘Elliott’, a cultivar with likely Mexican origins (although the ‘Elliott’ cultivar was a seedling selection from Florida). ‘Elliott’ generally outperformed the other seedlings in visual observations of resistance to salt injury and overall plant vigor and stood out with the greatest growth each year and cumulatively throughout the study. ‘Elliott’ had the highest K:Na ratio in 2019, shared the highest K:Na ratio in 2020 with ‘VC1-68’, was among the seedlings with the lowest leaf sodium concentrations during both years, and had the second lowest mortality of all the seedlings chosen. Another issue that pecan growers face is tree to tree variability that is reflected in nutrient acquisition within an orchard. It is important to have knowledge of variability so that each tree receives adequate nutrition. The orchard block mean leaf nutrient concentration should be high enough that all individual trees receive adequate nutrition. Practical leaf sampling of orchards requires sampling only a small portion of the trees randomly, and provides a mean value from which it is difficult to determine minimum (or maximum) nutrient concentrations extent in the sampled orchard block. To address this issue, a two-year experiment was conducted in an orchard in San Simon, AZ. The experimental plot consisted of ‘Wichita’ pecan pollinated with ‘Western’ (every fourth row). Soil and leaf samples were collected each year. Trunk measurements were made in the dormant seasons. Photosynthesis measurements of the ‘Wichita’ trees were made in 2019. The data were analyzed to determine magnitude and patterns of variability. Nutrient uptake varied between the cultivars. A lower mean and more variability in leaf zinc concentrations was found among the ‘Wichita’ trees than ‘Western’ during both years. We concluded that due to lack of variability sources within the orchard block, as well as finding little difference in row to row average mean leaf zinc concentrations, or in average mean leaf zinc concentrations of tree position within rows in either year, that position in the field was not the primary source of variability in leaf zinc concentration. From our 2019 data set we determined that a mean leaf zinc concentration of approximately 25 mg·kg-1 was needed to ensure that no more than 5% of the trees would fall below a target mean leaf zinc concentration (determined from previous research) of 15 mg·kg-1. This concentration is significantly lower than many published recommendations. Further, using the leaf nutrient with the highest coefficient of variance (zinc) for 2019 we determined a range of sample sizes and their associated relative margins of error from the true population mean. A sample size of 35 trees with a relative margin of error of 10% from the true population mean at 95% confidence is recommended for practical sampling purposes.
    • Bakhtin's Romantic Grotesque In Konstantin Vaginov's Novels: Alienation from the Soviet Society and the Pre-Revolutionary Culture's Loss

      Gordiienko, Anastasiia; Shamarova, Assem; Jens, Benjamin; Leafgren, John (The University of Arizona., 2021)
      This current work focuses on death and “mask” motifs in Konstantin Vaginov’s novels Kozlinaia pesnʹ (The Goat Song; 1926), Trudy i dni Svistonova (The Works and Days of Svistonov; 1929), and Bambochada (Bambocciada; 1929-30) by engaging with Mikhail Bakhtin’s discussion of the romantic grotesque that reflects people’s subjective perceptions of the world and themselves and the estrangement and hostility of a previously familiar world. The current research argues that Vaginov uses these motifs against the backdrop of romantic grotesque to illustrate his characters’ (Teptyolkin, Misha Kotikov, Kostia Rotikov, Ermilov, Evgenii, Toropulo, and Neizvestnyi poet) disengagement from the new, Soviet society. Being examined through Bakhtin’s theory of carnivalization, the romantic grotesque in the novels serves as the means for Vaginov to portray how the world, which is hostile and alien to the characters, now seems artificial, a parody of the real one to them. In addition to their alienation from the new society, Vaginov illustrates his characters’ inability to revive the old, pre-revolutionary culture as the surrounding byt (way of life) and lack of inspiration overpower them. Firstly, the present inquiry maintains that Vaginov characters’ fixation on death or fear of it represents their perception of the world as an imitation, their inability to bring the old culture back as well as their self-perception as half-humans and the living dead. Secondly, this work examines the characters’ wearing “masks” as the means to disguise their real, banal personalities. Lastly, this work details scholarship on Vaginov’s works in the context of the 1920s literature and on his polemic with Silver Age poets. This research examines the novels’ juxtaposition of the new world with the old one and expounds upon the characters’ striving to attain higher ideals, which clashes with everyday byt. The current work maintains that Vaginov was able to capture his own and his contemporaries’ feeling of culture’s loss, their alienation from the new society as well as their romantic grotesque self-perceptions and of the world around them.
    • Effects of Ketamine on Neural Signatures of Parkinson's Disease and a Novel String-Pulling Behavior Quantification System

      Cowen, Stephen L.; Vishwanath, Abhilasha; Falk, Torsten; Fuglevand, Andrew (The University of Arizona., 2021)
      The first part of the thesis reviews my investigations into the neural mechanisms underlying Parkinson’s disease (PD) and levodopa-induced dyskinesia (LID) and their treatment with levodopa and ketamine. The second part of the thesis summarizes our group’s development of a novel string-pulling behavior for assessing motor function in rodents.Part 1: Parkinson’s disease (PD) is a debilitating neurodegenerative disorder with motor and cognitive deficits. While levodopa is the leading treatment for PD, in many individuals long-term administration leads to Levodopa-Induced Dyskinesias (LID), which are uncontrollable involuntary movements. These side-effects are as debilitating as PD. A common neurophysiological feature of LID is the emergence of 80-Hz brain oscillations in the motor cortex. Ketamine, an FDA approved drug used in treating depression among other disorders and has been shown to alleviate LID symptoms in an animal model of LID. We used a unilateral 6-hydroxydopamine-lesion PD rat model to investigate the neural systems-level mechanisms of the effects of ketamine on LID. We found that ketamine administration was followed by reduced 80-Hz LID oscillations, increased gamma oscillations (~50 Hz), and reduced burst firing in individual neurons. One interpretation of these results is that ketamine triggers gamma activity that competes with and consequently reduces 80 Hz activity. Part 2: The development of complex motor tasks and behavioral analysis is crucial for understanding the workings of motor neurons and study motor deficits. We developed a novel behavior quantification system for a bi-manual string-pulling task. The system has a unique “infinite loop” and the capacity to simultaneous record neural activity. This integrated string-pulling system allows for investigation into the neural systems of motor behavior in healthy and disease populations.
    • Characterization of Human Induced Pluripotent Stem Cell (hiPSC)-Derived Epicardial Cells and Their Involvement in Arrhythmogenic Cardiomyopathy

      Churko, Jared; Kazmouz, Sobhi Gheath; Konhilas, John P.; Lynch, Ronald M. (The University of Arizona., 2021)
      Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disease, characterized by progressive fibrofatty replacement of the ventricular myocardium and ventricular arrythmias, potentially leading to sudden cardiac death. Most ACM cases are caused by mutations in the genes encoding the components of the desmosome, with almost half of such mutations found in the PKP2 locus. ACM pathogenesis, while extensively investigated, remains poorly understood, particularly regarding the process of fibrofatty replacement of the ventricular myocardium. The cellular source of the adipocytes that form the fatty deposits in ACM has not been fully elucidated yet. The epicardium, an epithelial cell layer surrounding the myocardium with multipotent and proliferative properties, is a strong candidate for the cellular source of adipocytes in the ACM heart. Furthermore, previous studies have shown that the inflammatory cytokine interferon-gamma (IFNγ) acts as an inhibitor of adipogenesis and considering the involvement of inflammation in ACM, this suggests a role that IFNγ signaling may play in ACM pathogenesis, particularly adipogenesis. In this study, human induced pluripotent stem cell derived epicardial cells (hiPSC-EPCs) with two different ACM-causing PKP2 mutations were used to investigate the cellular contribution of the epicardium to the fatty infiltration in ACM. It was hypothesized that epicardial cells contribute to ACM by increased migration into the myocardium and increased lipid accumulation potential and that IFNγ treatment would attenuate the adipogenic behavior of ACM hiPSC-EPCs. By investigating PKP2 localization, lipid accumulation, cell migration, and gene expression of ACM hiPSC-EPCs, it was found that hiPSC-EPCs with PKP2 mutations demonstrated higher cell migration in vitro but did not have a significantly higher lipid accumulation. Nevertheless, IFNγ treatment resulted in a decrease in lipid accumulation in ACM hiPSC-EPCs. Taken together, the findings of this study suggest that investigating the epicardial involvement in ACM may require studying the interactions of epicardial cells with other heart cell types in disease models that can more closely recapitulate the pathophysiology of the disease. Dissecting the molecular and cellular role of the epicardium in ACM pathogenesis would help increase the current understanding of the early events that bring about the disease’s phenotype and thus would help in the development of novel therapeutics that can address the root cause of ACM.
    • Mechanisms Underlying Noise-Induced PV+ Neuron Loss

      Bao, Shaowen; Hossainy, Nadia Nahal; Eggers, Erika D.; Pires, Paulo (The University of Arizona., 2021)
      There is a decrease of PV+ neurons in the primary auditory cortex of noise-exposed C57BL/6 mice. However, the mechanism behind this decrease was not clear. Therefore, the primary purpose of this study was to assess the possible cell death mechanisms involved in PV+ reduction. To help us identify potential cell death mechanisms to further look into, we first compared PV+ neuron reduction in noise-exposed C57BL/6 mice to noise-exposed FVB mice. C57BL/6 and FVB strains have different immune response profiles. Therefore, differences in PV+ neuron reduction in the primary auditory cortex of these two mouse strains can imply that pro-inflammatory cytokines might have a role in PV+ neuron density reduction. We observed different gap detection patterns and differences in PV+ neuron loss in the primary auditory cortex between noise-exposed C57BL/6 and FVB mice. Noise-exposed C57BL/6 mice displayed impairments in gap detection and reduction in PV+ neuron density in the primary auditory cortex. However, noise-exposed FVB mice did not show impairments in gap detection, and there was no change in their PV+ neuron density. Based on this finding, as well as previous studies linking tinnitus to pro-inflammatory cytokines, we examined PV+ neurons of noise-exposed C57BL/6 mice for signs of apoptosis and necroptosis. Both of these cell death mechanisms can be triggered by pro-inflammatory cytokines. TUNEL staining was used to identify apoptosis. Immunohistochemistry staining with the RIP3 primary antibody was used as a marker for necroptosis. We did not observe apoptosis in PV+ neurons in the primary auditory cortex of noise-exposed mice. Necroptosis was observed in PV+ neurons in the primary auditory cortex of noise-exposed mice (p < 0.05). Therefore, necroptosis might play a role in the observed PV+ loss in the primary auditory cortex of noise-exposed mice.
    • Polarization Design in Simulation, Laboratory, and Field Studies

      Kupinski, Meredith; Heath, James; Chipman, Russell; Pau, Stanley; Smith, Greg (The University of Arizona., 2021)
      Simulation: Vector Vortex Coronagraph Vector vortex retarders (VVR) are halfwave retarders with a spatially varying fast-axis. They are often used in coronagraph systems to create a vortex beam which blocks the dominant on-axis starlight. The VVR’s inherent polarization sensitivity creates the potential for deleterious polarization aberrations. Two polarization ray traces (PRT) for the first half of the Coronagraphic Debris Exoplanet Exploring Payload (CDEEP) vector vortex coronagraph (VVC) were performed to observe the Jones pupils for the field incident on the VVR. The first ray trace observed the system sans polarization elements to observe overall transmission. Amplitude plots showed 0.68 maximum in the on-diagonals compared to 0.01 maximum in the off-diagonals. The next PRT included a linear polarizer followed by a λ/4 wave-plate upstream to induce circular polarization incident on the VVR. Results showed a 0.30∼0.35% maximum for all amplitude plots and near π/2 differences between xx and yx, and xy and yy phases, indicating the expected circular polarization. This work was presented at Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave conference for which I was a co-author. Lab Experiment: Mueller Matrix PolarimetryDichroic filters are used by instrument designers to split a field of view into different optical paths for simultaneous measurement of different spectral bands. Quantifying the polarization aberrations of a dichroic is relevant for predicting the polarization states downstream. Polarization induced by the optical system could limit the performance of diffraction-limited systems, such as exoplanet imaging coronagraphs. A rotating retarder Mueller matrix imaging polarimeter was used to quantify the polarization properties of a 650 nm roll-off dichroic. The polarization properties of this commercial dichroic are compared at normal and 45◦ angle of incidence. These effects are not due to instrument calibration since no polarization-dependence was measured at normal incidence. Transmission measurements at 680 nm and 45◦ yield a 2.9 rad magnitude of retardance and 0.95 diattenuation. The dichroic is effectively a λ/4 waveplate at 630 nm and 45◦ angle of incidence. Therefore, large bandwidth illumination would produce polarization effects which depend upon the spectrum of incident light and if from an unknown source, could be non-correctable. This work was presented at the SPIE Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave conference for which I was first author. Field Experiment: UV Sky PolarimetryCirrus clouds are important to the radiation energy budget due to their temporal duration and >50% global coverage. The variety of ice crystal shapes and sizes in a cirrus cloud create challenges differentiating radiation insulated by the Earth’s atmosphere from that reflected back to space. The optical thickness of these clouds is often too thin to be sensed using any current passive satellite radiometers. Sensitivity studies in the UV have shown that the angle of linear polarization (AoLP) of solar radiation backscattered from thin cirrus clouds and thin liquid water clouds is rotated. In the context of insect vision, seminal studies have shown that shorter wavelengths are more useful for navigation under cloudy-sky conditions. This cloudy sky invariance in the UV will afford confidence that backscattered AoLP deviations can be attributed to the presence of thin cirrus clouds as opposed to nearby clouds. Pust and Shaw also demonstrated subvisual cloud detection in degree of linear polarization (DoLP) and AoLP in wavelengths as low as 452 nm. An Ultraviolet Stokes Imaging Polarimeter (ULTRASIP) was designed and developed for optically thin clouds and sky observations in the 360 nm - 450 nm range. Validation measurements were taken at 394 nm and show DoLP and AoLP sky-cloud difference in visually thin clouds. ULTRASIP is a time-modulated polarimeter rotating a wire-grid polarizer in front of a 16-bit, back-illuminated CCD sensor. Sky scanning on cloudy days will be compared to polarized light scattering models. This work will be presented at SPIE Polarization Science and Remote Sensing X conference in August 2021 for which I am a co-author.