• Role of Gilt in Melanoma Cells on Regulating in Vivo Tumor Growth

      Hastings, Karen; Macy, Anne; Lybarger, Lonnie; Kim, Suwon (The University of Arizona., 2022)
      The MHC I antigen presentation pathway in melanoma cells has a well-established role in immune-mediated destruction of melanoma. However, the role of the MHC II pathway in melanoma cells is not fully understood. Gamma-interferon-inducible lysosomal thiol reductase (GILT) is critical for MHC II-restricted presentation of multiple melanoma antigens by antigen presenting cells. While GILT and MHC II expression is typically limited to antigen presenting cells, GILT and MHC II can be expressed constitutively or induced by IFN-γ in melanoma cells. In human melanoma specimens, high GILT expression and an active and intact MHC II pathway are associated with improved survival. The goal of this project was to investigate a causal role for GILT in melanoma cells, using immunogenic Yale University Mouse Melanoma (YUMM) lines YUMM2.1, YUMMER1.7, and YUMMER.G. These lines constitutively expressed GILT, and MHC II expression was IFN-γ-inducible in a subset of cells under serum-free conditions. YUMM2.1 was selected as the primary model to assess the role of the MHC II pathway in in vivo tumor growth studies, because YUMM2.1 cells reliably formed tumors in mice. We have genetically engineered YUMM2.1 cells via CRISPR/Cas9 without GILT, verified the deletion, and selected a clone (#6) with similar in vitro proliferation as wild-type (WT) YUMM2.1 cells. When GILT-/- #6 cells were injected into immunocompetent mice, the resulting tumors had increased growth over time compared to WT tumors, but there was no clear association between tumor type and tumor onset or mouse survival. When these cells were injected into immunocompromised RAG1-/- mice, the resulting tumor growth, onset, and mouse survival, were inconsistent between experiments. Although further studies are needed to address these inconsistencies, in both experiments GILT-/- #6 had increased tumor growth in immunocompetent mice compared to WT tumors. Flow cytometry analyses showed that GILT-/- #6 tumors had fewer infiltrating T cells compared to WT, and a higher percentage of the infiltrating T cells were regulatory, supporting a potential role for T cells in regulating the in vivo tumor growth of GILT-/- #6 tumors versus WT tumors. However, to verify that the difference in tumor growth we observed in vivo was solely due to GILT expression in melanoma cells, we tested the in vivo tumor growth of GILT-/- YUMM2.1 cells transduced with empty vector or transduced with GILT. We found that GILT expression did not impact in vitro proliferation nor in vivo growth in immunocompromised mice. However, both tumors with the empty vector or GILT were rejected in immunocompetent mice, likely due to the expression of puromycin resistance from the lentiviral plasmid. Thus, mice genetically engineered to express puromycin resistance will need to be used in future studies and we are also designing lentiviral plasmids lacking puromycin resistance or other immunogenic reporter genes. In this manner, we will determine the effect of GILT expression in melanoma cells on regulating in vivo tumor growth.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • The Uneven Role of Water Treatment in Responding to Environmental Injustice: Government-Funded Reverse Osmosis Facilities in Rural Northern Guanajuato

      Bauer, Carl J.; Krupp, Aaron Samuel; Austin, Diane; Banister, Jeffrey (The University of Arizona., 2022)
      Across northern Guanajuato, water sources are going dry and groundwater contains levels of arsenic and fluoride that are dangerous for long-term human consumption. In writing this thesis i have two goals: first, to contextualize environmental injustice in northern Guanajuato and second, to interrogate the government-sponsored installation of reverse osmosis (RO) facilities, designed to treat, bottle, and sell drinking water in rural communities across the region. Towards the first aim, i begin by arguing that well-collapse, arsenic and fluoride exposure, and declining surface water flows in northern Guanajuato -- all of which are driven by agricultural groundwater extraction -- ought to be considered a case of environmental injustice. I then turn towards the second aim. First, i recount attempts taken to limit groundwater extraction and address contamination, including the government-sponsored campaign to install RO water treatment facilities in rural communities. Based on interviews and document analysis, i describe how this campaign emerged from the intersection of political pressure, community organizing, funding availability, and limited technological options to treat trace levels of arsenic and fluoride to Mexican drinking water standards. Drawing from empirical evidence including interviews, site visits, and policy documents, i classify and depict variations in how RO facilities are implemented, designed, operated, and maintained across rural northern Guanajuato today. Combining political ecology literature with empirical data, i analyze these practices by considering the political economy, accessibility, gendered labor dynamics, and ecological impacts of RO facilities in rural communities. To reframe how environmental injustice is produced in northern Guanajuato, i trace logics of extractivist capitalism and patterns of social difference since the Mexica inhabitants of Tenochtitlan met early Spanish colonizers and go on to argue that although RO may be able to prevent exposure to toxic levels of arsenic and fluoride for certain populations in the short term, it may also enable the extractivist status quo while repeating a familiar approach to perceived water scarcity: augmenting supply through technification without addressing demand. Indeed, if RO is installed without efforts to reduce groundwater extractions, wells will continue to go dry. I conclude by arguing for a pluralistic approach to water justice that both depends on short-term life-protecting technologies – which could include RO – while also pursuing other initiatives including policies that limit groundwater extractions and efforts to shift the dominant narratives and logics that drive extractivist injustice.
    • En-Face Preparations of the Medial Hypothalamus and Cilia-Driven Flow Across its Ventricular Wall

      Mirzadeh, Zaman; Cabrales, Elaine Flores; Mehta, Shwetal; Hammer, Ronald (The University of Arizona., 2022)
      The posterior basal third ventricle is situated in the midline, between the cerebral hemispheres, adjacent to hypothalamic nuclei pertinent to metabolic homeostasis. The neuroepithelium lining the ventricle in this region is composed of ependymal cells and tanycytes. Ependymal (E1) cells extend multiple motile cilia from their apical surface, while tanycytes extend two motile cilia (E2) or a single non-motile cilium (E3) from their apical surface. This unique arrangement of neuronal nuclei lined by a mixed neuroepithelium in contact with the ventricle is suggested to provide neurons in this region with privileged access to signaling factors and other molecules in the cerebrospinal fluid (CSF). However, CSF flow in this region has not been studied. Here, we characterized motile cilia-generated flow along the walls of the posterior basal third ventricle and found an unexpected asymmetry between the left and right sides. Flow generated by E1 cells on the left hemisphere was directed anterior and ventral, away from the tanycyte domain, while flow on the right hemisphere was directed posterior and ventral, towards the tanycyte domain. To explore cellular planar polarity—that is, polarity orthogonal to the apical-basal axis of an epithelium—that may underlie this difference in flow between the two hemispheres, we quantified “translational” planar polarity in E1 cells of this region. Interestingly, E1 translational polarity reflected the flow of CSF across the epithelium in the right hemisphere, but not in the left hemisphere. Altogether, this work provides a framework for understanding how CSF flow in this ventricular region regulates the exposure of CSF-circulating factors to the adjacent brain.
    • Thick Volume Holograms for Polychromatic Wavefront Selection

      Blanche, Pierre-Alexandre; Alcaraz, Pedro Enrique; Norwood, Robert A.; Takashima, Yuzuru (The University of Arizona., 2022)
      Presented is the theoretical basis and empirical evidence for a spatial-spectral holographic filtration system, referred to as the Advanced Volume Holographic Filter (AVHF), allowing for the discrimination of polychromatic wavefronts by range. State-of-the-art volume hologram-based imaging systems (VHIS) make use of a single, thick holographic grating as a spectral/spatial transmittance filter, allowing for depth-based, narrowband wavefront selection. However, imaging polychromatic sources at range using VHIS results in the loss of retrievable spectral information. Herein an optical system consisting of two coupled holographic elements is presented, with aims to increase the spectral bandwidth capabilities of the current volume hologram-based filtering approaches while maintaining range-based wavefront selectivity. Briefly, the AVHF is composed of a thin-volume hologram functioning as a pre-dispersive element used to Bragg match the spectra of an incoming wavefront onto a thick-volume hologram capable of depth-based wavefront selection. Our laboratory proof of concept demonstrated a resolvable spectral bandwidth increase from <1 nm using the single element VHIS method to ∼100 nm using the AVHF filter whilst maintaining the stringent VHIS spatial-selectivity performance for depth-based wavefront selection
    • Healing Waters: The Natural Mineral Springs of Roman Italy, their Curative Properties and Associated Deities

      Soren, David; Barcarolo, Monica; Blake, Emma; Romano, David (The University of Arizona., 2022)
      Bodies of water, be it lakes, streams, or rivers, have long been a focus of ancient worship,with some even having been thought to have had some degree of divine connection. The natural curative mineral springs scattered across the Italian peninsula are no exception to this practice. This study attempts to understand if a correlation exists between the deity, or deities, attached to a particular spring and the health benefits attested and the treatments practiced there. I focus on five spring sites, which I have chosen based on John F. Donahue’s classification of a Roman healing spa sanctuary (i.e., a place where a visitor could take the waters for various therapeutic and medicinal purposes) and the amount of information available on the following: a) their water’s properties, b) their architectural layout, and c) the evidence for the presence of divinities and cult worship/activity. Additionally, ancient literary sources consulted regarding the various ancient medicinal practices prescribed at mineral springs. I conclude that there is a lack of a direct correlation between the deity worshipped and the health benefits and treatments attributed to the waters, as the same deity could be present at multiple springs that have differing curative benefits and therapeutic treatments. Rather, it is the mineral composition of the waters that has the strongest influence over the treatments available, while the gods were a secondary focus of the sanctuary.
    • Multichannel Transcranial Acoustoelectric Brain Imaging in a Human Head Model

      Witte, Russell S.; Perkins, Charles Brigham; Chen, Nan-kuei; Utzinger, Urs (The University of Arizona., 2022)
      Epilepsy is a neurological disease that affects more than 50 million individualsworldwide. About 1/6 of these are non-responsive to drug treatment and are candidates for resective surgery for treatment. Present methods for localization of neuronal activity for individuals requiring resective surgery have either poor temporal or spatial resolution or are invasive. Transcranial Acoustoelectric Brain Imaging(tABI) is a novel imaging technique with the potential to non-invasively image neuronal activity with millimeter resolution. Prior developments have shown the feasibility of acoustoelectric imaging for 4D in-vivo heart and human head phantoms. In this thesis, multichannel acquisition of the acoustoelectric signal in a human head model is demonstrated as a steppingstone towards a new electrical brain imaging modality for humans. Challenges with acoustoelectric signal levels, signal-to-noise ratios, hardware configurations, and phantom fidelity are addressed. Sensitivities of 4 μV/(mA∙MPa) to injected current are reported for the multichannel measurement with 12 channels on a human head model. Insights gained from this thesis for hardware designs and setups may improve the sensitivity in the human head model by 20dB or more. The results demonstrate the improvement of acoustoelectric imaging techniques and the potential feasibility of tABI as a revolutionary imaging modality of neuronal activity.
    • Partner Support as a Buffer between Parental Depressive Symptoms and Parental Engagement

      Barnett, Melissa A.; Vasquez, Maria Belinda; Curran, Melissa A.; Speirs, Katherine (The University of Arizona., 2022)
      The risks and economic pressures experienced by low-income families can lead to psychological distress such as depressive symptoms (Masarik & Conger, 2017), which can impact parenting behaviors. The present study addressed how parental depressive symptoms might be a risk associated to parent-child relationships, especially positive parental engagement. Using a risk and resilience framework, the current study is the first to explore three forms of partner support (emotional support, financial support, and emergency child-care support) as potential protective factors that buffer the association between depressive symptoms and parental engagement among N = 3,165 mothers and fathers of three-year-olds. Participants were predominantly unmarried and from diverse minority ethnic backgrounds (Hispanic= 24%, Black Non-Hispanic=57%, White Non-Hispanic=17%, and other race=2%). Results indicated that parental depressive symptoms are negatively associated with positive parental engagement. The more depressive symptoms a parent is experiencing, the less likely they are to participate in positive parental engagement activities (e.g., singing, playing). Findings also suggested that emergency child-care partner support was a protective factor only for fathers. Emotional partner support and financial partner support were not a significant buffer for mothers or fathers. Findings highlight the need to address mental health needs in low-income families and explore complex associations between parenting practices and potential protective factors that promote resilience.
    • Renal Cell Carcinoma: American Indians, Metabolism, Metastasis, and Treatment

      Badger, Terry; Cordova-Marks, Felina; Lybarger, Lonnie; Briehl, Margaret (The University of Arizona., 2022)
      Renal cell cancer disproportionately affects American Indians/Alaskan Natives. This same population is also not included in published clinical trials and not reported on in published renal cancer clinical trials. Renal cancer treatment is needed that not only implements targeting new pathways or combinations of pathways that have not been targeted prior and integrating with traditional health. Almost 2/3 of American Indian’s report utilizing traditional medicine and cancer patients from this population report seeking traditional healers. New potential interventions should be created that combine traditional health with western medicine focused on metabolic pathways. Blocking in one treatment HIF1 and SIRT2; a separate treatment blocking VEGF and production of interleukins 6 and 8; and increasing BPTES to decrease glutamine; as well as adding in traditional aspects of health such as sweat ceremonies and usage of sage for example. Combining both western medicine and traditional health could increase the quality of life and outcomes for this population.
    • Eddavidite, a New Mineral Species, and the Murdochite (Cu12Pb2O15Cl2)-Eddavidite (Cu12Pb2O15Br2) Series

      Downs, Robert T.; Rosenblatt, Melli; Holliday, Vance; Thirumalai, Kaustubh (The University of Arizona., 2021)
      Eddavidite is a new mineral species (IMA2018-010) with ideal formula Cu12Pb2O15Br2. It has cubic Fm3m symmetry; a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromide analog of murdochite, with which it forms a solid solution series. The type locality is the Southwest mine, Bisbee, Arizona, U.S.A. Eddavidite also occurs in the Ojuela mine, Mapimí, Durango, Mexico. Eddavidite forms zones within mixed murdochite-eddavidite crystals. Spot analyses of Bisbee samples show up to 67% eddavidite component while Ojuela samples show up to 62%. Eddavidite-murdochite crystals show forms {100} and {111}; the habit grades from simple cubic through cuboctahedral to unmodified octahedral. Eddavidite is black and opaque with submetallic luster, and visually indistinguishable from intergrown murdochite. Its Mohs’ hardness is 4. Eddavidite exhibits good cleavage on {111}. The empirical formula, normalized to 12 Cu apfu is Cu12(Pb1.92Fe0.06Si0.06) (O15.08F0.02) (Br0.99Cl0.89•0.12). dcalc. = 6.33 g/cm3. dmeas. = 6.45 g/cm3. The crystal structure consists of corner sharing square planar CuO4 units, arranged in Cu12O24 metal oxide clusters, which encapsulate Br atoms. PbO8 cubes share edges with Cu12O24 clusters in a continuous framework. Eddavidite is one of only 10 mineral species with essential Br. Eddavidite crystallizes from bromine enriched fluids leftover from desiccation of paleo-seawater at its two known localities.
    • Sensing and Arresting Corrosion of Haynes 230 Alloy in Molten Chloride Salts at 800°C

      Gervasio, Dominic; Sasaran, Vlad; Farrell, James; Guzman, Roberto (The University of Arizona., 2021)
      The corrosion of metal in molten chloride salt is studied and lowered using a power supply. A particular emphasis is on the ternary eutectic sodium chloride, potassium chloride and magnesium chloride (MgCl2-KCl-NaCl) salt with a melting point of 387°C, because it is the high temperature heat transfer fluid of choice in electrical power generators and Haynes 230 alloy (H230), because H230 is a ductile metal which retains its strength at high temperatures (800oC). A potential negative of the open circuit potential of H230 metal alloy in ternary eutectic MgCl2-KCl-NaCl is applied, the cathodic potential generates a negative (cathodic) current for the reduction any oxidants, such as metal ions, oxygen and water, in the molten salt. The magnitude of the cathodic current is a signal of the level of oxidants present in the salt. Applying the cathodic potential also arrests ionization of metal, that is, corrosion of the metal. The increasing level of oxidant impurities, (particularly water) in the molten chloride salts causes the open circuit potential (OCP) of H230 versus a silver and silver chloride reference electrode (SSE) to shift positive, which gives a warning that the molten chloride salt heat transfer fluid is corrosive to metal. The OCP is crudely measured by direct readings of H230 and SSE with a voltmeter and refined by potentiodynamic scans of current versus potential of H230 versus SSE, where the H230 potential is scanned 30 millivolts starting negative of to positive of the OCP found with the voltmeter. A linear rate equation, called the Stern-Geary method is used to find corrosion potentials and estimate corrosion rates (CR) of H230 alloy in molten salt at various relative humidity (RH) of Argon atmospheres equilibrated with the molten salt. In oxidant free ternary MgCl2-KCl-NaCl eutectic molten salt, the OCP of H230 vs SSE is -866±24 [mV] and CR of 85±9 [micron/year]. In ternary eutectic molten salt equilibrated with a 40% RH Argon flow the OCP of H230 vs SSE is -363±1 [mV] and CR of 4670±780 [micron/year]. When a negative potential, of -200mV from OCP in anaerobic salt, is applied to a H230 working electrode in eutectic molten salt at 800oC and 100% RH Argon flow is flowed over salt for 20h, it was found that this H230 working electrode (WE) was cathodically protected, because the WE (cathode) lost only 0.0552g while the counter H230 electrode (CE), a “sacrificial” anode, lost 0.4513g. This gives a preliminary assessment a cathodic potential is effective for arresting corrosion of H230 metal in oxidant-contaminated salt at temperatures up to 800oC.
    • The Origins and Evolution of an Early Microbial Rhodopsin Protein

      Kacar, Betul; Sephus, Cathryn Dawn; Gutenkunst, Ryan; Duhamel, Solange (The University of Arizona., 2021)
      The advent of cellular organisms took place sometime between the start of prebiotic chemosynthesis on Earth and the evolution of the last universal common ancestor. Cellularity is now a fundamental organizational principle shared by all life on Earth and represents a key transition in evolutionary history. The emergence of cellular organization necessitated organisms to evolve a means to permit and regulate the exchange of material between the intracellular compartment and the extracellular environment. This capability implies both the ability to embed proteins into their membranes and to translocate molecules across their membranes. Other factors integral to the progression of early cellular life were the maintenance of transmembrane potential and chemiosmotic coupling for generating and conserving energy, and pigments to absorb light energy for photosynthetic and phototrophic metabolisms. Microbial rhodopsins, a superfamily of photoactive membrane proteins, have been suggested to be the simplest and possibly most ancient form of a phototrophic metabolism, likely providing a mechanism for microbial energy capture in Earth’s early shallow marine ecosystems. The retinal-based photosystem (rhodopsin) is composed of one retinal chromophore and one opsin protein. In this system, light absorption directly drives a conformational change in the protein via the isomerization of the retinal moiety to carry out biological functions such as ion pumping and ATP synthesis. Here, computational approaches were used to investigate the evolutionary history of rhodopsin proteins, combining phylogenic reconstruction and ancestral sequence inferences. Additionally, protein structure modeling and biophysical predictions were used to reveal ancestral rhodopsin functionality. Together, these results may shed light on the evolution of pigment-based metabolisms and prove beneficial for understanding the characteristics of early cellular membranes.
    • Occupancy of Terrestrial Mammal Populations in U.S. National Parks of the Southwest

      Prudic, Kathleen L.; Buckisch, Alexander; Steidl, Robert J.; Hubbard, John A. (The University of Arizona., 2021)
      North American mammal populations face many novel and powerful threats that are changing quickly over space and time. To complicate management and conservation decisions further, few established monitoring programs that can reliably detect changes in multiple mammal populations across species exist. Knowledge about the persistent threats and long-term trends of mammal populations are of immense importance to the public, the scientific community, as well as federal and state agencies charged with managing and protecting natural resources. We used an existing camera-based protocol to estimate occupancy of several terrestrial mammal species in seven U.S. National Parks in the Sonoran Desert. We surveyed 241 sites for 365 days to evaluate the detection efficiency (detected vs expected species) in different park units, evaluate a set of environmental variables with the potential to influence occupancy (ψ) and detection (p) probabilities of terrestrial mammals, and to estimate statistical power of the protocol to detect changes in occupancy. On average, we detected 76% (95% CI: 64% – 88%) of medium-to-large sized, native, mammals known to be present in surveyed park units. Mean occupancy across all park units ranged from 0.79 (0.10 – 0.86) for coyote (Canis latrans) to 0.12 (0.04 – 0.28) for black bear (Ursus americanus). Mean detection probability was highest for black-tailed jackrabbit (Lepus californicus) (0.35, 0.27 – 0.45) and lowest for mountain lion (Puma concolor) (0.06, 0.02 – 0.19). For many species, occupancy decreased as elevation and slope increased, and detection probability increased as precipitation increased during the study period. In addition, statistical power to detect changes in occupancy between two surveys was influenced mostly by occupancy and the number of sites surveyed. Power to detect changes in occupancy only increased to around 35 survey occasions (deployment days) above which it was relatively insensitive to increases in the number of survey occasions. Similarly, species with a higher initial occupancy achieved power to detect a change in occupancy faster (fewer survey occasions) and with less survey effort (fewer sites) than species with lower initial occupancy, whereas power was insensitive to changes in detection probability above 0.40. The camera trapping protocol we evaluated is sufficient to detect changes in occupancy with high power for species that are common (ψ = 0.80 – 0.99) and relatively easy to detect (p = 0.20 – 0.99), but not for species that are rare (ψ = 0.10 – 0.50) or difficult to detect (p = 0.10 – 0.19). For rare species, we suggest increasing detection probability by using lures and baits, increasing the duration of the survey period and surveyed sites, or strategically placing cameras in known areas of high activity. We conclude that the camera trapping design is well suited for simultaneously and cost-effectively monitoring terrestrial mammal communities within and between park units over the long term. This monitoring protocol has potential to inform conservation and management of mammals within the NPS and many other areas of North America.
    • On Lieb-Robinson Bounds in Open Quantum Systems

      Sims, Robert; Roon, Eric Brandon; Ercolani, Nicholas; Keller, Christoph (The University of Arizona., 2021)
      In 1971, A. Kossakowski \cite{kossakowski} axiomatized the study of the dynamics associated to non-Hamiltonian systems of quantum particles. These have come to be known as Open Systems, and through the work of Lindblad \cite{Lindblad76}, a classification of the generators of the dynamics of such systems in the Heisenberg picture -- for bounded generators -- is known (this is not so for the unbounded case). Following the work of Gorini, Kossakowski, and Sudarshan: \cite{gks}; we prove this classification scheme in finite dimensions, where it is accessible by computational means as in \cite{alickifannes}. With this knowledge, we prove a Lieb-Robinson bound for the irreversible dynamics in the case of time-independent interactions on a countable (possibly infinite) collection of sites. Such a result was proven by \cite{Nachtergaele} for the time-dependent case, in 2011.