• Ecologies of Care: How Cross Border Humanitarian Organizations Support Asylum Seekers in Arizona-Mexico Border Towns

      Bacelar da Silva, Antonio José; Blumberg, Julia Irene; Brewer-Osorio, Susan V.; Retis, Jessica M. (The University of Arizona., 2022)
      In early 2019 the Trump administration implemented the Migrant Protection Protocol (MPP), also known as the Remain in Mexico Policy. As a result of this rule, asylum seekers are now being sent to wait for their US asylum proceedings in Mexico (Ahmed, 2018). 647,919 individuals were apprehended during fiscal year 2021 with 110,400 individuals detained in May alone (Nationwide Enforcement Encounters, 2021). Since 2014, Southern Arizona has seen an unprecedented influx of asylum seekers, mainly from Central America, prompting a large public humanitarian response involving both the public and private/non-profit sectors. This research explains the emergence and dominance of private organizations for supporting migrants in the United States. It also explains the contextual and personal challenges confronting private organizations that support migrants in the United States. With this I seek to understand the varied landscape of care surrounding asylum seekers between the state, non-governmental organizations, and the public. This thesis is a qualitative study utilizing semi-structured interviews with leaders and volunteers of non-profit organizations involved in receiving asylum seekers on the Arizona-Mexico border. The main goal of this project is to document the motivations and impacts of this broad humanitarian effort in southern Arizona and to put a spotlight on organizations that work to humanize the border reality.
    • Sulfur Based Polymers and Polymer Magnetic Nanoparticle Composites: Novel Materials for Next Generation IR & Magneto-Optics

      Pyun, Jeffrey; Carothers, Kyle Jordan; McGrath, Dominic V.; Lichtenberger, Dennis L.; Loy, Douglas (The University of Arizona., 2022)
      This dissertation reports on new material developments as detailed in three chapters discussing the development of high Verdet constant materials containing magnetic nanoparticles (NPs) and one chapter discussing sulfur-containing polymers for infrared (IR) optics applications. The first three chapters will cover the synthesis and characterization of different types of magnetic nanoparticles followed by their incorporation into polymer systems to generate composite materials. Further, the processing techniques utilized to generate magneto-optic (MO) devices from these composites will be discuss as well as their performance related to both the processing methodology used and the properties of the nanoparticles. For chapters 2 and 3, additional experimental information and supporting data can be found in the corresponding appendix chapters. The fourth chapter will cover recent work analyzing the transparency of polymer materials in the IR.The first chapter is the first comprehensive review summarizing the field of high Verdet constant MO materials. The Faraday effect is a type of MO phenomenon where the polarization direction of linearly polarized light is rotated when passing through transparent media under the application of a magnetic field along the direction of the light propagation. At a certain wavelength and temperature, the angle of rotation is directly proportional to the strength of the magnetic field, the path length of the medium, and the Verdet constant of the material. For MO devices, maximizing the rotation angle of the light is desired for device miniaturization and fabrication cost and can be accomplished by increasing any of the aforementioned parameters, but for devices with size constraints and with the limitations of sustainable magnetic fields, high Verdet constant materials are desired. The development of high Verdet constant materials has been ongoing since the discovery of the Faraday effect in the mid-1800s and has come to encompass a variety of material classes from hard matter glasses, crystals, and ceramics, to soft matter small molecules and synthetic polymers, and some composite materials containing both hard and soft matter. The most widely used materials for MO applications have traditionally been glasses and crystals with Verdet constants on the order of 103-104 °/T·m at room temperature when measured in the visible to near-IR range. However, more recent work has shown promising soft matter systems composed of small molecules, polymers, and nanoparticle-polymer nanocomposites with enhanced Verdet constants ranging from 104-106 °/T·m. Chapter 1 is designed to give a broad overview of the different types of high Verdet constant materials with an emphasis on the recent development ultra-high Verdet constant materials such as conjugated polymers and nanoparticle-polymer composites. The second chapter will discuss the preparation of polymer-nanoparticle composite Faraday rotators. As mentioned previously, most applications of Faraday rotators use a variety of hard matter materials to accomplish MO rotation. These materials are however limited by low Verdet constants (when compared to many soft matter systems) which has led to an increased interest in soft matter both for increased Verdet constants and for enhanced processing capabilities. The new type of MO material discussed is based on MO active cobalt ferrite (CoFe2O4) nanoparticles combined with poly(styrene) (PS) to form solution-processable composites. This study examines the importance of exchanging the surface ligands on the CoFe2O4 nanocrystals to polymer ligands that are more compatible with the PS phase of the composite. With surface compatible ligands, the NPs could be dispersed in a polymer matrix at variable loadings from 2.5-15 wt%. The solution processing techniques employed for this system allowed the MO response to be tuned by simply varying the NP loading and the number of layers in the composite. The Faraday rotators were prepared by a multilayer polymer film construct wherein alternating layers of the NP-polymer composite and cellulose acetate were spin coated allowing for an increased path length of the MO active NP-polymer layers with protective layers of cellulose acetate. These multilayered Faraday rotators demonstrated a nearly 10X increase in Verdet constant compared to a terbium gallium garnet reference material at 1310 nm and demonstrated the importance of exploring soft MO materials for enhanced MO responsive materials. The third chapter will discuss an expansion on the previous work with CoFe2O4-polymer composites. The previous work established a construct for how Faraday rotators could be produced by solution-processing using alternating layers of MO active materials to achieve a strong MO response. In this work polymer coated cobalt (Co) nanoparticles were used and offered several advantages over the previously used CoFe2O4 NPs. The synthetic strategy employed to produced Co NPs uses a native polystyrene ligand which eliminated the ligand exchange processing step and provided enhanced dispersion in the polystyrene matrix. This enhanced dispersion allowed for NP loadings up to an astonishing 50 wt% with the same tunability as the previous system. In addition to solution processing, the enhanced dispersion allowed for the formation of composites that could be melt-processed into free standing films with significantly increased thicknesses. The synthetic strategies employed additionally allowed for the synthesis of a range of particle sizes from 9 to 17 nm. This allowed, for the first time, a systematic study Verdet constant with the size dependent magnetic properties of the NPs. Due to both the increased NP loading and a stronger magnetic moment from Co NPs compared to CoFe2O4 NPs the measured Verdet constants were 2-3 orders of magnitude higher than our reference terbium gallium garnet material or our previous NP-polymer composites. The fourth chapter will cover recent work on IR imaging and the importance of uniform reporting techniques for IR transparency. There have been recent reports of new IR transparent polymers that only report the IR transparency measurement as thin films. This chapter demonstrated that thin films of poly(methyl methacrylate) PMMA (a demonstrably poorly IR transmissive polymer) could mistakenly be described as an IR transparent, transmissive optical polymer. To definitively illustrate the non-uniformity of polymer films and windows reported for IR optics, PMMA windows of progressively increasing thickness were prepared for FTIR measurements to quantity optical transmittance in the IR spectrum, along with MWIR imaging experiments. These results were then compared to poly(sulfur-random-diisopropenylbenzene) (poly(S-r-DIB)), our previously established MWIR transparent polymer. The report provided both qualitative and quantitative analysis of PMMA and p(S-r-DIB) and how only reporting on thin film properties of polymers can lead to misrepresentation of the polymer’s IR transparency. These results set a standard for how IR transparency in polymers should be reported.
    • Examining Social Vigilance and Associated Physiological Effects Across Types of Situational Stress

      Ruiz, John M.; O'Neill, Riley M.; Sbarra, David; Hamann, Heidi (The University of Arizona., 2022)
      Emerging work over the past four decades supports psychological stress as a critical determinant of cardiovascular disease (CVD). Previous research has supported social vigilance, or active watchful monitoring of one’s social environment for interpersonal challenges or threats, as a candidate biobehavioral process linking stress exposure to adverse cardiovascular reactivity and recovery profiles. Review of findings in this area reveals the need for research examining whether experimentally controlled contextual vigilance cues evoke the hypothesized biobehavioral responses. The current study randomized 135 undergraduate young adults (49% male, 51% female; Mage = 19 years, SDage = 4 years) to one of three videogames standardized as all first-person shooter scenarios, with the manipulation across games being type of situational stress (challenge, threat, neutral). Participants’ dispositional social vigilance was measured via trait assessment, and participants’ cardiovascular reactivity (CVR) was measured prior to, during, and after the experimental task. Analysis of covariance (ANCOVA) models revealed higher stress games evoked significantly more CVR than the neutral game, especially in the case of threat condition. Participants in the high threat condition also demonstrated the least overall recovery to baseline blood pressure. No effects of vigilance disposition were observed during gameplay and modest effects of higher vigilance were associated with better physiological recovery, in contrast to expectations. These findings contribute to understanding how higher threat social situations may connote CVD risk through pull for greater preparatory monitoring and the acute cardiovascular responses corresponding to that behavior.
    • Statistical Relationships Between Groundwater, Climatic, and Economic Factors in Southeastern Arizona

      Colby, Bonnie; Condon, Laura E.; Pereira, Mekha; Meixner, Thomas (The University of Arizona., 2022)
      Hydrologic, climatic, and economic factors interact in complex ways to influence groundwater conditions. These relationships can be difficult to measure and simulate but are important to understand for long-term water resource planning purposes. Knowledge of factors linked with groundwater levels in a basin can help water managers develop targeted and effective strategies to incentivize desired water use outcomes. Existing studies focus on areas of large-scale irrigated agriculture or highly urbanized areas, and utilize data on groundwater use. In much of rural Arizona, and much of the world, groundwater use data is not available and difficult to collect. The goal of this study is to instead explore responsiveness of groundwater level data to economic signals in rural areas. We focus on two rural areas in southeastern Arizona, along the upper portion of the Santa Cruz and San Pedro watersheds. Using an econometric approach, we employ a fixed effects regression model with a groundwater level metric as the dependent variable, and climatic and economic factors as explanatory variables. We find well counts, housing units, per capita income, and planted acreage have statistically significant relationships to groundwater levels in these rural areas at the annual scale. We also highlight some of the challenges of data availability when performing econometric studies related to groundwater in rural areas. Despite these challenges, this unique approach could be helpful to understanding influences on groundwater conditions in areas of the world where water use data is unavailable.
    • Applications of Psychological Game Theory to Self-Handicapping and Auctions

      Dufwenberg, Martin; Mannahan, Rachel; Blume, Andreas; Deimen, Inga; Friedenberg, Amanda (The University of Arizona., 2022)
      Psychological game theory, established by Geanakoplos, Pearce, and Stacchetti (1989) and extended by Battigalli and Dufwenberg (2009), is a framework that allows players in games to have belief-dependent utilities. Belief-dependent utilities are useful for capturing preferences such as reciprocity, anger, guilt, and image concerns among others. Throughout the three chapters in this dissertation, I use the framework of psychological game theory to analyze two applications: self-handicapping and auctions. In my first chapter, I model rational agents with preferences for maintaining self-esteem. These preferences are belief-dependent, in that the agent's utility depend on a function of their ex post expectation of their own ability level, which they initially do not know. If this function is strictly concave, these agents may seek out actions that inhibit their performance. This phenomenon is called self-handicapping. I then consider policy implications if the population has self-esteem concerns. I use the theory from my first chapter to derive testable hypotheses, which I implement in my second chapter. Specifically, I design an experiment to test for self-handicapping behavior. Subjects answer questions from a Raven's Progressive Matrices test, a test of intelligence. Each question includes an option to randomize the answer choice, a self-handicapping strategy. The subjects are exposed to different information about their scores. This varies the impact of the Raven's test on their self-esteem. I hypothesize that there will be more use of randomization when subjects receive more information about their scores. Finally, in my third chapter, I characterize the pure strategy equilibria in complete information auctions when bidders have reciprocity preferences. The equilibria under standard preferences persist, but two additional types of equilibria arise. In the Refusing to Lose equilibrium, the winning bidder does not have the highest value for the item. This type of equilibrium is sustained by negative reciprocity. In the Kind Ties equilibrium, three or more bidders tie for the winning bid at a price below all of their values for the item. This type of equilibrium is sustained by positive reciprocity.
    • Abnormal Anatomy of the Auditory Cortex in Schizophrenic Brains with Auditory Hallucinations

      Musiek, Frank; Bushor, Jillian; Velenovsky, David; Norrix, Linda; Ruiz, John (The University of Arizona., 2022)
      Background: Evolving research in the psychiatric literature has suggested that the auditory cortex region is smaller in people with schizophrenia who experience auditory hallucinations than in normal control individuals. These findings are not without controversy. While there has been significant research considering volumetric variance in pathologic brains with AH, there is a paucity of data considering the influence of morphology and surface area of primary auditory structures. Purpose: The purpose of this set of studies was to evaluate and compare the following variables in schizophrenic and control brains, both between groups and between hemispheres within groups: surface area of Heschl’s gyrus (HG) and planum temporale (PT), length of the Sylvian fissure (SF), length of the posterior extending ramus of the SF, and the morphological variants of HG, PT, and the posterior ramus. Evidence of morphologic variance or surface area differences in populations that are prone to experiencing auditory hallucinations may provide new or additional insight into the role of these neuroanatomical structures in central auditory processing during auditory hallucinations. Hypothesis: Based on the previous literature we had several hypotheses: (1) in separate structure analyses with regards to surface area, there will be reduced asymmetry for primary auditory structures (HG & PT) in schizophrenic brains with hallucinations compared to controls; (2) there will be reduced typical asymmetry in Sylvian fissure (SF) length for schizophrenic brains with hallucinations compared to controls; and (3) there will be consistent patterns of morphologic differences in at least one category of Heschl’s gyrus, planum temporale, or posterior ramus variants between schizophrenic brains with hallucinations and control brains. Methods: Imaging analysis was conducted using BrainVISA Anatomist software and MRIcron software to assess 51 control brains (102 hemispheres) from the Open Access Series of Imaging Studies (OASIS) repository and 51 schizophrenic brains (102 hemispheres) obtained from the NUSDAST (Northwestern University Schizophrenia Data and Software Tools) database. These neuroimaging softwares were used to quantify surface area of HG and PT, morphology of HG and PT, length of SF, and angle of the posterior extending ramus of SF. Results: This study found a lack of typical asymmetry between right and left HG in schizophrenic brains, and a significantly larger HG in the right hemisphere of controls compared to schizophrenics. There was also reduced asymmetry of the SF length in schizophrenics compared to controls. No significant findings were established for either PT surface area or morphological classifications of HG, PT, or posterior ramus. Key Words: Auditory Hallucinations, auditory cortex, anatomy, Heschl’s gyrus, planum temporale, superior temporal gyrus, Sylvian fissure, posterior ramus, ascending ramus, schizophrenia Abbreviations: Auditory Hallucinations (AH), central auditory nervous system (CANS), Heschl’s gyrus (HG), planum temporale (PT), planum polare (PP), primary auditory cortex (A1), Sylvian fissure (SF), schizophrenia (SZ), superior temporal plane (STP), supramarginal gyrus (SMG), region of interest (ROI)
    • Correcting Structured Illumination Aberration Effects in Structured Illumination Microscopy

      Peng, Leilei; Jacobson, Alex; Kieu, Khanh; Liang, Rongguang (The University of Arizona., 2022)
      The resolution of an optical microscope is limited to roughly 250 nm for biological imaging. This is due to the wave nature of light which causes an optical system to be diffraction limited according to the wavelength of light involved and the numerical aperture of the system. In order to image finer structural details of biological samples it is necessary to image beyond the diffraction limit. There are several methods for doing this. One method for imaging beyond the diffraction limit is structured illumination microscopy (SIM), a type of fluorescence microscopy where high frequency information is put into low frequency space by using a periodic illumination pattern at different phases. One of the difficulties with this method is that experimentally the periodic illumination pattern will never be ideal since it will suffer from the aberration effects of the system. This thesis presents a computer program with an algorithm to correct for the aberration effects in the periodic illumination which corrects independent of any specific type of aberration introduced into the structured illumination. The computer program first simulates one dimensional linear SIM, adds in aberration effects, and then corrects the image. The results show that the algorithm improves the superresolution image for the conditions of 0.5 wave, 1 wave, and 2 wave aberration effects in the structured illumination. With this computer program as a foundation, future work could expand the program to include two-dimensional nonlinear SIM for experimental applications.
    • Abnormal Anatomy of the Auditory Cortex in Schizophrenic Brains with Auditory Hallucinations: A Systematic Review

      Musiek, Frank; Schefer, Madelyn; Velenovsky, David; Norrix, Linda; Ruiz, John (The University of Arizona., 2022)
      Background: Due to the high prevalence of auditory hallucinations in schizophrenic individuals (60-80%; Lim et al., 2016), this review will focus on evidence of neuroanatomical abnormalities found in key auditory structures of this clinical population. Identifying atypical anatomy of these areas can inform our understanding of the mechanisms underlying the experience of auditory hallucinations as well as potential deficits in central auditory processing, providing a rationale for the involvement of audiologists in diagnosis and treatment of auditory hallucinations. Purpose: The goal of this review is to describe the auditory neuroanatomical differences in schizophrenic individuals who experience auditory hallucinations compared to normal individuals who do not. Further, it will also explore how these differences in neuroanatomy may be related to central auditory processing dysfunction and auditory hallucinations. Methods: A review of existing literature published from 1960-2020 was conducted to summarize and compare neuroanatomical abnormalities of key auditory structures in schizophrenic brains. Relevant studies published between the years of 1960 and 2020 were identified using the following online databases: Google Scholar, PubMed, PSYCnet, and Mendeley, as well as books, chapters, and bibliographies. For each of the listed databases, search terms included “schizophrenia” AND “auditory hallucinations” AND “auditory cortex” AND “anatomy” AND “Sylvian fissure” OR “superior temporal gyrus” OR “Heschl’s gyrus” OR “planum temporale” OR “(central) auditory processing dysfunction” OR “dichotic listening”. Results: Findings from previous anatomical studies are in strong agreement, having identified structural abnormalities of Heschl’s gyrus, planum temporale, and the Sylvian fissure in schizophrenic brains, suggesting that these auditory structures potentially play a role in the experience of auditory hallucinations. Conclusion/Discussion: This review summarizes and compares available evidence of neuroanatomical abnormalities in the auditory cortex of individuals with schizophrenia who experience auditory hallucinations. Anatomical studies investigating auditory structures in schizophrenic brains indicate abnormalities of Heschl’s gyrus, planum temporale, and the Sylvian fissure, particularly a reduction in hemispheric asymmetries. These anatomical deviations have implications for functional auditory processing. Evidence of the involvement of these key auditory structures provides rationale for audiologists to collaborate with psychiatrists in the diagnosis and treatment of auditory hallucinations. This review also suggests the need for future research to investigate potential correlations between neuroanatomical variances in schizophrenic brains and audiological findings. Key Words: Auditory Hallucinations, schizophrenia, auditory cortex, structure, anatomy, superior temporal gyrus, Heschl’s gyrus, planum temporale, Sylvian fissure, central auditory processing, dichotic listening Abbreviations: Auditory hallucinations (AH), auditory verbal hallucinations (AVH), central auditory nervous system (CANS), inner speech model (ISM), corpus callosum (CC), superior temporal gyrus (STG), Heschl’s gyrus (HG), planum temporale (PT), gray matter (GM), gray matter volume (GMV), white matter (WM), white matter volume (WMV), anterior cingulate cortex (ACC), temporo-parietal junction (TPJ), right ear advantage (REA)
    • Comparison between the Early Chinese and Japanese Labor Movements: A Focus on Historical Conditions

      Lanza, Fabio; Xiang, Jie; Schlachet, Joshua; Ren, Hai (The University of Arizona., 2022)
      Labor movements represent social protection systems designed to serve as survival means for workers, usually executed in the form of picketing, peaceful demonstrations, and boycotts. This paper explores past studies on the labor movements in China and Japan, compares and contrasts their characteristics, and explains the various factors that made the Chinese socialist labor movement extend beyond Japan’s. The Japanese labor movement was disproportionately instigated by non-government and non-political reasons. A significant proportion of the factors that spurred the Japanese labor movement was associated with the need to increase workers’ wages and status. On the other hand, nationalism, spurred by oppression, was the most important factor that contributed to the success of the Chinese Socialist labor movement. Imperialist antagonism greatly abused Chinese labor influence through private enterprises, indirectly disassembling the country’s feudal economy. The early industrialization experienced in Japan was dissimilar to that experienced in China because the latter was subjected to increased colonial presence, while Japan was in the process of initiating the Meiji Restoration and westernization. Between 1900 and 1920, China was in a semi-colonial and semi-feudal state while Japan was a colonialist country. Unlike China’s labor movement, the emergence of the Japanese labor movement was sudden and without any formal organization. Japanese labor movements also had minimal rivalry from various inter-city workers’ movements compared to the Chinese labor movements. Since China and Japan were experiencing different national situations between1900 and1920, they experienced different impacts of nationalism on their labor movements.
    • Scatter Based Novel Imaging Systems

      Ashok, Amit; Yang, Shu; Peng, Leilei; Pau, Stanley K.H. (The University of Arizona., 2022)
      Imaging is the process of reproduction of an object’s form. Image science is a multidisciplinary field concerned with the generation, collection, duplication, analysis, modification, and visualization of images.Traditionally, the image of an object is generated by gathering optical power reflected or absorbed by the object directly with a detector array in a one-to-one manner. For example, in optical photography, reflected or emitted photons from object are directly captured by optical elements (e.g. lens, mirror) and focused onto a detector array. However, in many scenarios where such direct imaging is not feasible, one is forced to gather information that is only indirectly related to the object. In some extreme cases, we are forced to work with only scattered photons from the object of interest. In this work, we explore two of these special cases and propose two novel indirect imaging (scattering-based) approaches operating at different wavelengths. The first indirect imaging approach we consider a novel non-line-of-sight (NLOS) imaging technique. Non-line-of-sight imaging refers to the imaging of an object that is not directly visible from the viewer/imaging perspective. A classic NLOS setup usually involves emission and collection of photons actively with time-of-flight measurements. To accurately measure a photon’s traveling time, most approaches employ expensive and exotic optical sources and detectors such as ultrafast laser and ultra high-resolution single photon avalanche detector (SPAD). In this work, we instead propose a novel passive NLOS imaging method that works with ambient light illumination and employs only commonly available imaging elements. We develop a light path order based image formation model, a learning-based model parameter estimation process, and successfully demonstrate instant passive NLOS imaging. We discussed the limitation of this technique and possible applications We then shift our focus to ultra-short wavelength or higher photon energy. In this part, we study a different type of imaging referred to as X-ray diffraction tomography (XRDT). X-ray diffraction tomography is a tomographic imaging of the coherent scattering profile (X-ray form factor) of an object and its material. Coherent scattering is one of three forms of photon interactions possible in the X-ray photon energy ranging from 10 kev to 200 kev. It occurs when X-ray photon energy is relatively small compared to the ionization energy of the atom. When a coherent scattering event happens, the photon does not have enough energy to liberate the electron from its bound state and no energy transfer occurs. Instead, the X-ray photon gains momentum from the micro-structure of the material and undergoes a change in its direction (scatter). Therefore, the scatter direction contains vital information of the micro-structure of the material and is unique to different materials. The scattering pattern is called momentum transfer function or X-ray form factor. It is considered as the golden standard in material classification. In this work, we explore the inherent sparsity in the X-ray form factors and develop a sparsity regularized reconstruction algorithm to perform maximum-a-posteriori estimation for X-ray diffraction tomography. We demonstrate the possibility of achieving higher energy resolution with limited number of photon, which allows our system to run on a lower signal-to-noise ratio.
    • How do Wood Anatomical Traits in Salix Vary in Response to Flooding? A Case Study from the Yenisei River, Siberia

      Meko, David; Thaxton, Richard Douglas; Hu, Jia; Panyushkina, Irina (The University of Arizona., 2022)
      Recent, record-breaking discharge in the Yenisei River, Siberia, is part of a larger trend of increasing river flow in the Arctic driven by Arctic amplification. These changes in magnitude and timing of discharge can lead to increased risk of extreme flood events, with implications for infrastructure, ecosystems, and climate. To better understand the changes taking place, it is useful to have records that help place recent hydrological changes in context. In addition to an existing network of river gauges, extreme flood events can be captured in the wood anatomical features of riparian trees, which help identify the most extreme flood events. Along the lower reaches of the Yenisei River, Siberia we collected white willow (Salix alba) samples from a fluvial fill flat terrace that occasionally floods when water levels are extremely high. Using these samples, we use an approach known as quantitative wood anatomy (QWA) to measure variation in radial cell dimensions, particularly fiber lumen area and cell wall thickness. We then use Pearson correlations to compare these measurements to observed records of flood stage. We hypothesize that (1) intra-annual changes in wood fiber size (LA) and cell wall thickness (CWT) in Salix rings can be quantified using QWA, and (2) these patterns are related to flood magnitude and/or duration. We find that normalized wood fiber CWT best captures intra-annual density fluctuations (IADFs) found in Salix rings. For some trees, time series of normalized CWT correlate with July flood durations, which have profoundly changed since the 1980s. Understanding how riparian vegetation responds to extreme flood events can help us better manage riparian ecosystems and understand changes to the Arctic hydrological regime.
    • Peridynamics for Failure Prediction in the Presence of Material Nonlinearity and Finite Deformation

      Madenci, Erdogan; Behera, Deepak Kumar; Venkataramani, Shankar C.; Zhupanska, Olesya; Silling, Stewart A.; Spencer, Benjamin W. (The University of Arizona., 2022)
      This study examines the failure modeling of materials exhibiting nonlinear behavior and reduced dimension structures using peridynamic (PD) theory. Among the existing PD models, PD constitutive correspondence approach is adopted in the development. PD correspondence approach offers a way to use constitutive equations from classical continuum mechanics by defining a nonlocal deformation gradient tensor. However, using the original definition of deformation gradient leads to spurious oscillations in the solution. This work uses a bond-associated deformation gradient with the peridynamic differential operator to eliminate these oscillations. The numerical modeling assumes the quasi-static loading conditions, and the solution is obtained using the implicit technique with the Intel PARDISO solver using the exact tangent stiffness matrix. PD models are systematically developed for rubber-like materials, polymers exhibiting high stretch, and epoxy adhesives. The force density vectors for rubber materials are derived using the neo-Hookean constitutive equation. The weak form of PD equilibrium is used to impose the boundary conditions directly on the last layer of material points. Stretch-based criterion is used to eliminate interaction during failure simulations. The validity for predicting damage is demonstrated through simulations of experiments concerning progressive damage growth in pre-notched styrene-butadiene rubber sheets. The formulation is then extended for the polymer that can sustain high stretches. Anand’s model and Talamini-Mao-Anand’s model are used to derive force density vectors. The fidelity of this PD model for predicting large deformation, progressive damage, and rupture is established by comparison with experimental measurements of polymer sheets with defects under displacement-controlled tensile loading. To model epoxy adhesives, a viscoelastic material model in the presence of finite deformation is employed to derive the force density vectors. The relaxation modulus for the time-dependent behavior of the viscoelastic material is described in terms of the Prony series. The model performs well in predicting interface failure of lap joint configurations. A new approach is presented to impose traction and displacement boundary conditions while solving for the strong form of PD equilibrium equations without a fictitious boundary layer. The domain is split into inner, outer, and boundary layer regions. In the “interior” region, the equilibrium equations are based on the nonordinary state-based (NOSB) peridynamics. In the “outer” region, the equilibrium equation is derived based on PD differential operator (PDDO). The PD form of traction components based on the PDDO enables the imposition of traction conditions in the actual “boundary layer” region. The displacement constraints are also enforced directly in the real boundary layer. The present approach is free of the unphysical displacement kinks near the boundaries. Also, the displacement predictions maintain the smoothness between the outer and inner regions. The displacement predictions agree well with FE results for all combinations of boundary conditions. The approach is adopted to model the creep behavior of stainless steel at high temperatures. Liu and Murakami's creep damage model is adopted to derive the force density vector. The approach is validated by considering the creep deformation of uniaxial and 2D plane stress stainless steel specimens subjected to a range of constant stress. The results compare well with the experimental measurements and analytical solutions. A generalized PD beam model is formulated based on the Simo-Reissner beam theory. The governing equations are developed based on the form invariance of the first law of thermodynamics under rigid body motion. Nonlocal measures of strain and curvature are defined using the PD differential operator (PDDO). By employing a quadratic strain energy density function for the material response, the present approach is validated by considering numerical examples of beams undergoing large deformation.
    • Improving Soil Water Retention and Nutrient Availability Using Carbon Inputs in Desert Croplands

      Blankinship, Joseph C.; Hoglund, Shelby Rae; Fidel, Rivka B.; Jacobs, Katherine L.; Schuch, Ursula K. (The University of Arizona., 2022)
      Considering that the southwestern United States provides many of the specialty crops to feed the entire nation, it is vital to maximize use of water and fertilizer in croplands in this region. Meanwhile, intensifying droughts exacerbate cropland dependence on irrigation water. Therefore, solutions are needed to maintain cropland productivity. Adding carbon-rich organic amendments temporarily improves soil properties by increasing water and nutrient retention, but benefits are short-lived as organic amendments degrade quickly in hot, arid climates. Biochar is an organic amendment that can potentially improve long-term cropland soil health, which is the ability of soil to store and provide water and nutrients for plant growth. Biochar provides a relatively stable carbon source and can increase water and nutrient retention. Most studies on the effectiveness of biochar for these purposes have been conducted in temperate agroecosystems, but few studies examine effects of biochar on soil properties in croplands of the desert southwest U.S. Therefore, the purpose of this research is to deepen understanding of effects of carbon inputs (i.e. biochar and compost) to retain more water and provide plant-available nutrients in an irrigated desert cropland.
    • Reframing Anxiety as Excitement in Job Seekers: A Within-Person Field Experiment

      Gabriel, Allison S.; MacGowan, Rebecca Lee; Ellis, Aleksander P.J.; Slaughter, Jerel E. (The University of Arizona., 2022)
      While job seeker’s anxiety may be adaptive (e.g., Gabriel et al., 2021), it may also undermine individual’s weekly experiences of self-efficacy (e.g., Bandura, 1997), inhibiting job search behaviors. Prior scholarship (Brooks, 2014) finds that individuals who reappraise anxiety as excitement improve their performance outcomes and mitigate the negative effects of anxiety. Drawing from the social cognitive theory of self-regulatory behavior (Bandura, 1997; 2001) and the broaden-and-build theory of positive emotions (Fredrickson, 2001), I conducted a weekly emotion reappraisal intervention reframing job seeker’s job search anxiety as job search excitement. Results of the field experiment indicated that the intervention was positively related to feelings of excitement about the forthcoming week of job seeking. Further, these feelings of excitement were positively related to both creative job search and networking self-efficacy. At the end of the week, job seekers who had done the intervention and experienced excitement and creative and networking self-efficacy related to their job search reported engaging in focused job search effort as well as effort towards finding their dream job. As such, this intervention provides a promising avenue for improving weekly job search experiences.
    • Food Aid and Kitchen Controversies: Cooking Together in the City of Hope

      Alvarez, Maribel; Renkert, Sarah Rachelle; Austin, Diane; Carney, Megan; Green, Linda; Vásquez-León, Marcela (The University of Arizona., 2022)
      Over forty years ago, women across Lima, Perú’s poorest neighborhoods decided to take their community’s need for food into their own hands. Amidst an economic downturn that swept across Latin America in the last decades of the 20th century, these volunteers, the socias, formed comedores populares (communal kitchens). The socias combined their resources to cook for their families, while selling meals at an affordable price to their neighbors, investing all profit in the next day’s meal. In the early 1980s, the Peruvian government began opening state-sponsored comedores, providing participating kitchens with food aid. As state-sponsored comedores have evolved over the past four decades, they have become sites of contested meaning and significance amidst a confluence of embedded structural inequalities, conflicting sociopolitical subjectivities, and a politics of false generosity. While the state has long used the comedores for political ends, a practice which remains entrenched in today’s Peruvian political practices, outside observers have blamed comedores for reproducing irresponsibility, underdevelopment, malnutrition, political corruption, and the perpetuation of systemic injustices. These overlapping complexities have created a context in which comedores are facing increasing pressure to close, forcing socias to fight to keep their kitchens open. Drawing on ethnographic research with state-sponsored comedores in Huaycán, Lima, Perú, colloquially known as ‘The City of Hope,’ this research explores the relationship between the inside meaning of comedores for participating socias and the external challenges socias confront as they struggle to continue cooking together. While food aid programs such as the comedores are unlikely to upend Perú’s underlying structural challenges, for many socias, the comedores are a vital resource for ameliorating the hardships of chronic economic precarity, while also providing a valuable space of social solidarity and camaraderie. In examining these dynamics, this research addresses broader debates around food aid distribution, the violence of precarity, and the value of communal spaces within a neoliberal socioeconomic context. Additionally, in turning to the experiences of comedor socias in Huaycán, this dissertation considers how deep-seated injustices in poor communities have produced predictable and preventable suffering and death due to COVID-19.
    • Accessing the Superintendency: Challenges, Pathways, and Characteristics of Successful Latina Leaders

      Bertrand, Melanie A.; Kelsey, Isabel; Deil-Amen, Regina; Combs, Mary C. (The University of Arizona., 2022)
      Historically in the US, White males have dominated the superintendency accounting for 68.14% (Tienken, 2021). The figures are more despairing when it comes to Latina female superintendents who account for only 1% of superintendents nation-wide (Tienken, 2021). At the time of the study, in Arizona, 6% of Latina females held the superintendency compared to 61% of White males and 32% of White females (ADE, 2021). The disparity between male and female superintendency is concerning especially since 45% of Latinex students attend public schools in Arizona (ADE, 2021). Therefore, for this qualitative study, I used Critical Race Theory and Latino Critical Race Theory as a theoretical framework to research the experiences of 10 aspiring, practicing, and retired superintendents in Arizona K-12 public schools. I used snowball sampling to recruit participants. Data was collected using semi-structured interviews. I used CRT counter-stories to narrate the intersectional realities of Latina leader findings. My findings indicated that the patriarchal hegemonic structure in K-12 public schools presented intersectional, ethnic, gender, and political challenges to Latina leaders’ career mobility. Most of the Latina leaders discussed how the challenges affected their career mobility, causing internal and external effects. However, three of the participants stated that they did not experience challenges related to either race/ethnicity or that their career mobility was not impacted. The findings also revealed that relocating provided out-of-network access to the superindency. Additionally, participants used strategies and resources to manage their challenges and the stress associated with it. Finally, the study highlighted Latina leader’s successes, characteristics, and factors that might prevent Latina leaders from accessing the superintendency. These findings suggest implications for school districts to provide support systems and unbiased hiring practices for Latina leaders. The findings also imply possibilities for inclusion of transformative Latina literature in leadership literature and administrative preparation programs.
    • Good Thinking

      Comesaña, Juan; Kearl, Timothy Rion; McKenna, Michael; Cohen, Stewart; Sartorio, Carolina (The University of Arizona., 2022)
      Good Thinking is a collection of papers about abilities, skills, and know-how and the distinctive but often overlooked—or explained away—role that these phenomena play in various foundational issues in epistemology and action theory. Each chapter, taken on its own, represents a fairly specific intervention into debates in (i) epistemic responsibility, (ii) the nature of inferential justification, and (iii) connections between inference and action. But taken collectively, these chapters constitute fragments of a larger mosaic of commitments about the explanatory priority of abilities in normative theories. One distinctive argumentative strategy employed throughout Good Thinking is its placing special emphasis on what might be called “bad thinking”: defective judgments borne out of cognitive short-circuiting, incoherence or self-doubt, depression, or anxiety. The underlying motivation for this is that much of what we can learn about good thinking is only revealed at the margins, where thinking has in some respects gone bad without being entirely spoiled.
    • Fissure-Fed Volcanism on Mars and Earth

      Hamilton, Christopher W.; Sutton, Sarah; Andrews-Hanna, Jeffrey C.; Byrne, Shane; Carter, Lynn M.; McEwen, Alfred S. (The University of Arizona., 2022)
      I present investigations of the formation and degradation of volcanic landforms associatedwith fissure eruptions on Mars and Earth. A theme of my research is the use remote sensing data to investigate the morphology of landforms and active processes on Mars and the Earth. The morphologies of sinuous channels in Late Amazonian volcanic terrain onMars invite comparisons to channels formed by lava or water on Earth. I tested channel formation hypotheses by lava or water by conducting detailed geomorphological mapping in a region adjacent to the base of Olympus Mons. We interpreted the channels and associated fossae to be formed by alternating episodes of dike-fed fissure eruptions and groundwater release due to subsurface heating by sill emplacement. This alternating sequence of dike and sill emplacement, and associated surface eruptions of lava and water, is evidence of a complex, distributed volcanic system influenced by the tectonic stresses exerted by Olympus Mons as it continued to grow through the Amazonian Period. In a novel field study of the 2014–2015 Holuhraun fissure eruption vents in northernIceland, I created a topographic time series to measure the degradation of a large spatter rampart over the first five years post-eruption. I investigated the effects of spatter deposition on the styles and rates of erosion and found two distinct modes of topographic changes. The interior walls of the vent undergo discrete rockfall events, while the exterior slopes decrease in elevation overall, but show minimal evidence of gravitational sliding of unconsolidated scoria. The results of this study have implications for current vent landform evolution models, which predict slope changes by diffusive processes only. I propose instead a conceptual model that incorporates the probability distribution of rockfalls on the interior and diffusive processes on the exterior to better describe the earliest stages of vent erosion. I also present an analysis of the quality, precision, and accuracy of digital terrainmodels generated with stereo images from the Mars-orbiting High Resolution Imaging Science Experiment (HiRISE) camera, specifically applied to the measurement of active processes with time series of orthorectified images and digital terrain models.
    • Ultra-Sensitive and Selective Whispering Gallery Mode Microtoroid Chemical Sensor

      Su, Judith; Li, Cheng; McLeod, Euan; Kolesik, Miro (The University of Arizona., 2022)
      Optical Whispering gallery mode (WGM) microresonators, which benefit from an ultra-high quality (Q) factor and small mode volume to significantly enhance light-matter interaction, stand out from other sensors, and are utilized in a variety of biochemical sensing or physical parameter detection applications. Physical or chemical reactions occurring in the evanescent field of the polymer-treated microtoroid equatorial plane will be translated into variations of the WGM spectra, which will, in turn, be recorded and analyzed through techniques such as frequency locking, balanced detection, and post data processing. The overall platform is known as the Frequency-locked optical whispering evanescent resonator (FLOWER) system. The performance and characteristics of ultra-sensitive and selective WGM gas sensors are evaluated and demonstrated in this dissertation. Two approaches to further improve the system are proposed, one based on plasmonic near-field enhancement to improve the sensitivity and the other on a fiber metrology method using Rayleigh backscattering to eliminate the thermal noise of the sensing system. Finally, another sensing application using the dual-FLOWER system for particle shape analysis is introduced.
    • Group Oriented Strategic Technologies for Adversarial Privacy Enhancement

      Brandimarte, Laura; Brooks, Catherine; Sidi, David; Brandimarte, Laura; Brooks, Catherine; Braitberg, Victor; Bambauer, Jane (The University of Arizona., 2022)
      Privacy-enhancing technologies (PETs) have long been divided according to the role of trust in their design, with “hard” PETs distinguished in particular by an aim to minimize trust. This work adopts a different perspective on PETs, and describes the class of group-oriented strategic technologies for adversarial privacy enhancement (GOSTAPEs) focused on the long term causes and conditions of privacy over time. The work then motivates GOSTAPEs as a research agenda for PET design. A survey of the PET landscape from the hard-/soft- PET perspective is presented first, with the rest of the work falling to separate discussion of group-orientation, adversariality, and strategy. Throughout, the discussion of GOSTAPEs focuses on technologies of measurement, including a botnet used to measure privacy practices on the web, a public transparency and reputation system for data brokers, and a formal measure of database privacy risk based on plausible deniability. The work concludes by gathering themes from the strategic perspective that have emerged, and looking to the future of PET design.