• Irrigation in Southeast Morocco: Effects on Rural Livelihoods

      Gerlak, Andrea K.; Elder, Alison D.; Evans, Tom; Snyder, Katherine (The University of Arizona., 2019)
      Irrigated agriculture and the liberalization of land markets are promoted as engines for rural development and economic growth. However, in practice they often reinforce existing social and economic disparities, create conflict over land and water resources, and degrade the natural environment. In southeastern Morocco, irrigated agriculture has expanded rapidly in a desert area formerly characterized by traditional small-scale oasis agriculture and livestock grazing. The country’s 2008 Green Morocco Plan (GMP) to modernize and expand agriculture is fueling this expansion with incentives and subsidies encouraging agricultural growth and foreign investment. This paper investigates development processes around irrigated agriculture in southeastern Morocco in an area immediately surrounding the town of Boudnib and its eight satellite villages, an area undergoing significant change and illustrative of larger economic challenges underway in Morocco. It follows a mixed methods approach including document analysis, semi-structured interviews, a roundtable discussion and surveys, to examine the effects of irrigation on labor and income opportunities and water supply. This research aims to highlight the voices and experiences of local people affected by irrigation alongside those of government, NGO leaders, and foreign investors. The findings suggest that despite the GMP’s “green” label and claim to fight poverty through the provision of economic opportunities for rural people, job opportunities are low-paying and unreliable and water supply is decreasing. This means that outsider investors and farmers benefit in the short-term from free groundwater and cheap local labor, leaving local people to deal with the long-term consequences of ecological damage. These findings have implications for other water-stressed parts of the world, especially for developing countries implementing irrigation-based agricultural development.
    • Waiving Nepa to Build A Border Wall: From Conflict to Collaboration on the Arizona-Mexico Border between 1990 And 2017

      López-Hoffman, Laura; Rodriguez-McGoffin, Mariana Sofia; Baldwin, Elizabeth; Marsh, Stuart (The University of Arizona., 2019)
      Signed in 1969, the National Environmental Policy Act (NEPA) is the cornerstone of US environmental law. It requires the government to complete an environmental review for every planned action that may have a significant impact on the environment. It also requires extensive public input. Thus, NEPA enables citizens to participate in environmental decision-making. But, in 2005, Congress passed a law—called the REAL ID Act—that gave the Department of Homeland Security, which oversees the Border Patrol, the right to waive NEPA for any action taken along the border. This essentially cut border communities off from the ability to influence Border Patrol decisions. Subsequently, the Border Patrol built a network of communication towers linked by 550 miles of barriers and roads without formally consulting the public. Despite popular perceptions that the Border Patrol has overlooked environmental concerns, in one instance the Border Patrol provided funding to the Fish and Wildlife Service to build a fish barrier to prevent invasive species from entering the San Bernardino Wildlife Refuge. This action helped protect the most ecologically intact watershed, and the only undammed watershed, in the whole southwestern United States. And yet, because of the absence of NEPA, which would have required informing the public, no one seems to know about this and other steps the Border Patrol has taken to mitigate environmental damages. This study highlights some of the ways in which NEPA enhances cooperation between agencies, strengthens accountability mechanisms and facilitates public participation.
    • Microstructure-Dependent Electrochemical Properties of Chemical-Vapor Deposited Poly(3,4-ethylenedioxythiophene) (PEDOT) Films

      Ratcliff, Erin L.; Arnold, Sean; Loy, Doug; Muralidharan, Krishna (The University of Arizona., 2019)
      Conductive polymer electrodes hold exceptional promise in energy conversion technologies and bioelectronics due to their inherent mechanical flexibility and synthetic tunability of physical, chemical, and electronic properties. Solution-processing is favorable to retain low-cost but can often result in heterogeneity of physical and electronic structure due to non-conjugated side chains and polyionic dopants creating insulating domains. Such a complex landscape limits control and systematic understanding of fundamental properties including electrical and ionic transport and rates of electron transfer central to overall device efficiencies. Chemical vapor deposition (CVD) offers a promising route to simultaneously synthesize and deposit conductive polymer films at low temperatures (<150°C) with controllable microstructure. Herein we use the CVD technique to synthesize and deposit different paracrystalline films of poly(3,4-ethylenedioxythiophene). Using grazing incidence wide-angle x-ray scattering, we demonstrate three different orientations of the π-π packing direction to yield thin films with face-on, edge-on, and isotropic character. These different microstructures have direct impact on the electrochemical conditioning of the redox properties of the films. We show that electrochemical properties, as defined by energy and power density, are highest for crystalline materials with edge-on orientation to facilitate ion transport while still retaining reasonable electrical conductivity.
    • The Role Of Religion, Politics And Gender In The Visitation By The Master Of The Retablo Of The Catholic Kings

      Cuneo, Pia; O'Bert, Andrea Elena (The University of Arizona., 2019)
      The Visitation and the other seven panels in the altarpiece by the Master of the Catholic Kings are still a mystery in many ways. However, analyzing them in their political, religious and gender contexts suggests that they serve as a powerful example of political propaganda produced in favor of the Catholic monarchs. The altarpiece allows for the veneration of the saints and in the Master’s altarpiece in particular, the key saint being depicted is the Virgin Mary. It is currently believed that the Master’s altarpiece was commissioned by Queen Isabella and King Ferdinand. Their daughter, Juana of Castile, was perceived by the public as being mentally unwell and thus not fit for leadership. In an effort to improve her image before she married Philip of Hapsburg and assumed the throne, they had this altarpiece created with Mary made in the image of Juana. Throughout the scenes of Mary’s life that are depicted, she embodies many characteristics of the ideal woman: pious, maternal and obedient. In supporting that Juana embodies these traits, the King and Queen hope to counter the public’s concern about Juana’s mental illness and to provide an alternate image of her as the perfect queen to lead Spain.
    • Simulating Crack Initiation and Propagation in Ceramic Matrix Composites using Peridynamics

      Madenci, Erdogan; MITTS, CODY AARON; Missoum, Samy; Naboulsi, Samir (The University of Arizona., 2019)
      This study uses Peridynamics (PD) to predict the crack propagation in ceramic matrix composites (CMC). This investigation employs both the strong and weak form of the PD equations of motion. The solution approach based on the strong form of PD was applied to three-dimensional models. The weak form was developed to apply natural and essential boundary conditions. It was subsequently applied to axisymmetric problems. Both solution methods were executed using a high-performance computer to simulate the damage propagation of a CMC. For both approaches the results indicate that the critical stress ratio and fracture energy ratio between the coating and matrix have a strong influence on crack deflection in a CMC. Also, it was observed that the smaller these ratios are the earlier the crack deflection in the coating occurs.
    • Estimating Leaf Area Index of Arid Land Cotton Crops with Unmanned Aerial System (UAS) Multispectral Data

      Slack, Donald; Harders, Sara J.; Thorp, Kelly; Didan, Kamel (The University of Arizona., 2019)
      The use of unmanned aerial systems (UASs) can aid in assessing plant health via leaf area index (LAI) and percent canopy cover more efficiently than traditional methods and without the destruction of plant matter from taking ground-based plant measurements. Equipping a UAS with a five band multispectral camera will expand on prior research at a finer scale than previously possible with satellite imaging or other remote sensing techniques. In this study, a comparative analysis of traditional ground-based plant measurement methods to emerging UAS and multispectral technology was used to determine the advantages of UASs for crop monitoring. Ground truth data included canopy cover and plant height ground-based plant measurements, LI COR 2200C Plant Canopy Analyzer LAI data, and LI-COR Li-3100 Area Meter LAI data. Results indicate plant height may be assessed using UAS multispectral data up to mid-season growth before boll development, which may be attributed to canopy closure. This study suggests that LAI and percent canopy cover can be predicted through multispectral image analysis, which implies a strong role of UASs for crop monitoring in the future.
    • A Comparison Of The Representation Of Women In The Northern Renaissance And Modern Day: The Occult, Female Sexuality, And The Media

      Barr, Sandra; Soehl, Morgan Marie (The University of Arizona., 2019)
      In this essay I will compare depictions of women in Northern Renaissance prints and the modern media in order to reveal the roots of stereotypical representations of women. Women who go against the status quo are represented as witches so as to prey on societal fears of female sexuality and dominance. Printmaking and the modern media both represent women with a binary understanding of femininity. How these stereotypes of women are represented in the media today have roots in Northern Renaissance prints that were heavily influenced by the Malleus Maleficarum, the first treatise on witches and the occult. This treatise utilized gendered stereotypes to describe witches, thus generating a fear of the occult that manifests as a fear of female power, particularly as it pertains to sexuality. Part one focuses on the Malleus Maleficarum as it was applied to various works of art during the 15th and 16th centuries. Part two will prove that the iconographic references utilized during the Northern Renaissance have continued on as unconscious bias within society, manifesting in the way women are represented in the media. Understanding these roots is an important step towards understanding why women have historically been relegated to a second-class status.
    • Desertification In Mongolia: Untangling Problems, Effects, And Policy Solutions

      Gerlak, Andrea K.; Bat-Erdene, Bat-Orgil (The University of Arizona., 2019)
      In recent years, much attention has been given to Mongolian capital city, Ulaanbaatar in regard to its concerning issue with environmental pollution, particularly air pollution during winter months. People have been desperately finding a solution to Ulaanbaatar’s air pollution due to numerous negative consequences to the health of people living in Ulaanbaatar. The majority of the actions taken by the Government of Mongolia and other international organization have focused on structural methods to reducing the fossil fuel emission coming from houses in Ulaanbaatar’s low-income areas called the ‘ger district’. Regardless of the efforts and money spent, the air quality worsened each year. Therefore, this thesis will examine a different approach to finding a solution to this problem. The thesis identified desertification as the main underlying cause of air pollution. Due to desertification, a rural-urban migration increased rapidly over the past few decades, increasing the number of residents living in the ger district, who burn fossil fuels, which is the main source of air pollution. Instead of trying to find a mechanical solution, the thesis aimed at directing the attention to the main cause of air pollution; and furthermore, offered policies that could alleviate the current crisis situation in Ulaanbaatar, Mongolia.
    • The Role of Complex Instruction in the Pursuit of Learning Goals: It’s A Marathon, Not a Sprint

      Wood, Marcy B.; Hackett, Maggie; Gunckel, Kristin L.; Civil, Marta; Felton-Koestler, Mathew D. (The University of Arizona., 2019)
      The Role of Complex Instruction in the Pursuit of Learning Goals: It's a Marathon, Not a Sprint By Maggie Hackett Despite a long-standing call in mathematics education for more student-centered teaching practices, instruction in the K-12 classroom is difficult to shift. Research on professional development experiences provide some insight into why teaching practices persist, but they do not tell the entire story. It is well documented that teachers' beliefs, learning goals, and instructional contexts also factor into the decisions teachers make about their practices. The research outlined in this study focused on making sense of these factors, as teachers contemplated changes to their instructional practice to incorporate Complex Instruction. Using a case study approach, I observed three elementary teachers during their mathematics lessons over the course of a semester. I interviewed them prior to and after the instruction to document what connections they made between their beliefs and goals to their anticipated and enacted practices. Analyzing the data through the lens of practicality theory, teachers' considerations were categorized according to the instrumentality, congruence, and cost of enacting Complex Instruction. Findings showed that teachers were able to bridge their current practices towards an idealized version of Complex Instruction, in an effort to better meet their goals. An alignment along the congruence dimension of practicality theory seemed to most impact the teachers' ability and willingness to adopt the practices. Lastly, the process of making changes to instructional practice takes an incredible amount of time. The findings of this study can inform those who support teachers as they work to align beliefs, goals, and practices.
    • Acute Mental Injury in ICU Nurses

      McRee, Laura D.; Sharp, Paul Jacob; Reed, Pamela G.; Baldwin, Carolina (The University of Arizona., 2019)
      Nurses in the intensive care unit (ICU) are subject to extreme conditions of patient care. When that patient care does not progress as projected, they can suffer feelings of anger, nightmares, insomnia, sadness guilt, anxiety, flashbacks, and withdrawal from co-workers and family members. This project holds as it is conceptual framework of Dr. Martha Newman’s theory of Health as an Expanding Consciousness, as such, illness is seen as an imbalance and wellness is the restoration of balance. This project draws parallels between nurses’ feelings of grief and coping in the presence of traumatic events and untimely deaths in the ICU. This is done through a qualitative, descriptive, and open-ended interview study; as well as through a quantitative, demographic, and professional characteristic written survey This project is a replication of Dr. Michelle Sato’s 2015 project Nursing Experiences of Grief and Coping in the ICU. This project has shown that when positive coping mechanisms are in place, nurses are less likely to show symptoms of mental injury.
    • Application of Sediment Transport Theory in Environmental Science and Engineering

      Duan, Jennifer G.; Zhou, Kang; Lansey, Kevin E.; Valdes, Juan B.; Gerba, Charles P. (The University of Arizona., 2019)
      Sediment exists in different water bodies and its transport can be associated with different problems such as irrigation water contamination and infrastructure integrity compromise. Applying sediment transport theory helps better understand and solve these problems. Therefore, this dissertation reports on the experimental investigation of pathogenic microorganism resuspension and bridge pier scour based on sediment transport theory. The first research focused on the study of the resuspension of Escherichia coli and MS2 bacteriophage from bed sediment in irrigation canals. A set of laboratory experiments was conducted to investigate relation between the concentration of Escherichia coli and the MS2 in moving water and flow properties and the size of bed sediment. Results showed when bed material is sandy loam, their quantity in water increases with the shear stress on bed surface. However, for a sandy bed, their presence in water has no apparent correlation with flow properties. The amount of MS2 virus in water was greater at low flow velocity and shear stress than Escherichia coli because the size of the MS2 virus is much smaller. Finally, an empirical relation was formulated for calculating the maximum allowable Escherichia coli concentration in sandy loamy bed sediment. The second research focused on the investigation local scour around a group of three piers with different sizes, spacing, and attacking angles. The results of the scour pattern showed the sheltering effect of the upstream piers and interaction between horseshoe vortex and wake vortex. Based on the phenomenological theory of turbulence flow, an analytical equation was formulated for predicting the maximum scour depth. The significance of key parameters were evaluated using the statistical F-test. The coefficients in the equation were determined by the experimental data from this and other studies. The results showed pier diameter, pier spacing, actual pier width, flow depth, Froude number, and sediment size are important parameters for determining the maximum scour depth. The third research focused on the study of the turbulence flow field around the three pier group. Mean flow vectors, turbulence intensities were analyzed based on the instantaneous velocity measured by Acoustic Doppler Vectrino Profiler. Two pier spacings of 1 and 5 times the pier diameter and two attack angles of 0 and 30 were used to study the effect of pier spacing and attack angle on the flow field. A strong sheltering effect of upstream pier in tandem alignment was observed when piers spacing is small. Horseshoe vortices around the middle and downstream piers were enhanced when the piers were in staggered alignment. Distributions of bed shear stress showed that when the scour is in equilibrium, the bed shear stress in the scour hole is smaller than the approaching bed shear stress.
    • Computational Experiments Quantifying the Scale-up of Geometric Facies Structure on Conductivity and Transport through Composite Porous Media

      Winter, C. Larrabee; Clark, Colin L.; Guo, Bo; Kennedy, Tom; Venkataramani, Shankar C. (The University of Arizona., 2019)
      We develop reduced-order, phenomenological models for effective conductivity, and for mass transport, in highly heterogeneous, composite porous media. Composite porous media consist of two or more distinct materials that occur in irregularly shaped, coherent blocks, called facies. Due to sparse sampling of the subsurface, uncertainty of facies structure is epistemic, and we conduct computational experiments that use thresholded random fields to generate realistic realizations of composite porous media. Darcy’s law is assumed to hold at local (mesoscopic) and large (macroscopic) scales, and flow is simulated through the facies structure to quantify the effects of the random, irregular configuration of the facies. Scale-up is addressed by Monte Carlo simulation. In the first chapter, simulations verify the importance of the percolation threshold, vc , which determines three regimes in effective conductivity that coincide with three corresponding regimes in the spatial variability of the flow fields. In the second chapter, further simulations motivate a continuous time Markov chain model that is able to explain anomalous dispersion in highly heterogeneous media. The model is parameterized directly from the statistics of the trajectories of synthetic particles that flow through the medium. In the third chapter, a stochastic optimization algorithm generates composite media characterized by the curvature along the facies interface, thereby controlling the connectedness of the facies structure to quantify its effects on conductivity and mechanical dispersivity in composite porous media.
    • Investigation of Hydrologically Mediated Interactions at the Critical Zone through Controlled Experimentation

      Troch, Peter A.; Alves Meira Neto, Antonio; Ferre, Paul; Chorover, Jon; Meixner, Thomas (The University of Arizona., 2019)
      The critical zone (CZ) extends from the bottom of the weathered bedrock to the top of the tree canopies. CZ processes and fluxes, such as weathering, nutrient and carbon cycling are critical for the provision of critical ecosystem services that support life on the planet. CZ function is regulated by its internal structure, as inferred for example from concentration-discharge (C-Q) relationships. On the other hand, CZ fluxes are slowly and constantly shaping its features, as seen for example in rates of mineral weathering across climatic gradients or the coevolution of soils, vegetation and topography across an elevation gradient. Understanding the relationships between CZ function and structure becomes fundamental for enhancing our capacity to predict and mitigate impacts from short term environmental disturbances to medium and long-term alterations imposed by climate change. This PhD dissertation explores the interplay between structural development and hydrologic behavior and response of the CZ. My objective was to provide empirical understanding of the following question: How water fluxes and states modulate and are subject to changes in CZ structure. In order to pursue this goal, I’ve taken advantage of the experimental set-up hosted at Landscape Evolution Observatory (LEO) - Biosphere 2, which allows for a high degree of observability and control. The system under study consists of a 1 m3 sloping lysimeter filled with fresh un-weathered crushed basalt. Due to its slope, the lysimeter can be taken as a model of a hillslope, a landscape unit in which most biogeochemical interactions occur. In the first chapter of this dissertation, I address the role of hydrology in shaping the incipient heterogeneity. Throughout 2 years, the lysimeter experienced sequences of hydrologic inputs (irrigation) and drying periods under bare soil conditions, leading to detectable biogeochemical patterns. Here, my main question was how observed geochemical weathering states and microbial diversity and abundance are influenced by hydrologic behavior within two years of imposed wet-dry cycles. For this purpose, an intensive sampling procedure was undertaken for the assessment of the incipient heterogeneity within the system, followed by modelling of the hydrologic history summarized in terms of moisture states, cumulative fluxes and average residence times of water. I’ve found significant imprints of hydrologic behavior on both biological and geochemical patterns of heterogeneity, which suggests a common framework to assess how heterogeneity develops in incipient systems. More specifically, the amount of time spent by water within the subsurface appeared, or the residence time (RT) appeared to be the main control on observed geochemical states and spatial distribution of different fila of microorganisms. The second and third chapter combined represent an effort to experimentally observe residence times of water within the subsurface. Chapter two presents a method to directly observe the transport of solute within the model system using Electrical Resistivity Tomography (ERT). For that, I have equipped the lysimeter with electrodes to be used with an ERT acquisition system, allowing me to obtain high frequency temporal images of soil resistivity along 5 cross-sections of the lysimeter. The tracking of solute movement through ERT was based on the estimation of the spatial distribution of fluid electrical conductivity (EC) within the lysimeter. It is important to note that the estimation of the spatial distribution of EC has traditionally been a challenge in ERT studies at field and laboratory scale, especially under transient conditions. The presented method has therefore the potential to be applied at different settings and find uses beyond the scope of the estimation of RT. The third chapter of this dissertation deals with the extension of an existing theory on the estimation of transit time distributions (TTD) within the context of controlled experimentation. Transit times of water (TT) are of great importance in hydrologic sciences, since they are related to the very basic question of the fate of water once it reaches the landscape. The theory of TTD represents a lumped-systems approach towards the understanding of TT at natural landscapes and has a long history of application in both natural as well as artificial systems. However, due to its lumped nature of system representation, TTD theory does not explicitly address the internal variability of flow pathways within the subsurface and therefore benefit from understanding of the mechanistic basis that they represent. The study presented in chapter 3 introduces a method for the estimation of the varying ages of water within the lysimeter under a prescribed hydrologic forcing allowing for an approach towards the time-variability of TTD
    • Improving Student Experiences of the University of Arizona’s Nurse Practitioner Virtual Objective Structured Clinical Examinations

      Flamm, Kristie; Tatton, Jordan T.; Knight, Elizabeth; Prettyman, Allen (The University of Arizona., 2019)
      Background: Universities are providing education via online platforms, but this creates uncertainties about how to evaluate students in healthcare professions. Objective structured clinical exams (OSCEs) have been a tool to evaluate healthcare professionals for decades. The University of Arizona (UA) has implemented virtual OSCEs to evaluate nurse practitioner (NP) students. Objective: The purpose was to evaluate experiences with virtual OSCEs for NP students at UA and make changes in this process to improve student experiences. Design: One-group interview followed by a second group post-test quality improvement project. Setting: Interviews were conducted via an online Zoom meeting platform. Faculty and students also utilized Zoom for OSCE. Standardized patients participated in the UA simulation lab. Participants: Ten NP students from the 2016 FNP cohort. A second group of seven NP students from the 2017 FNP cohort. Measurements: Ten NP students were interviewed with open response questions developed by the projector director, based on the review of a previous survey. A second group of seven students completed a virtual OSCE, with changes made from interview responses, and a post survey of Likert scale questions and free responses. Results: Themes of the interview included, providing a grading rubric before the virtual OSCE, ensuring that faculty/standardized patients provided feedback, standardized faculty expectations, and emphasizing pertinent clinical skills. In the post survey, students (100%) reported that they ‘somewhat agreed’ or ‘strongly agreed’ with feedback received from faculty/standardized patients, expectations were managed by receiving the rubric beforehand, and that the virtual OSCE process was a “good educational experience.” Conclusion: The results suggest that after making changes to the current virtual OSCE, students had an improved experience.
    • Remindings in Declarative Concept Learning

      Tullis, Jonathan G.; Zhang, Di; Gomez, Rebecca; Smith, Eric D. (The University of Arizona., 2019)
      Remindings are a fundamental building block of cognition that prompt people to retrieve relevant experiences when faced with novel stimuli. Remindings may allow learners to generalize across the common aspects of the earlier learning instance and the current one to gain the knowledge that will be used in the later categorization. The benefits of remindings in category knowledge have been well-established in the literature, yet the effectiveness of remindings in learning declarative concepts remains an open question. The goal of the thesis is to assess the role of remindings in near transfer and far transfer in learning declarative concepts. Across two experiments, remindings were encouraged by presenting new examples that were similar to prior studied examples, or remindings were discouraged by presenting new examples that were different than previously studied examples. However, across both experiments, no evidence was found that similar or different novel examples enabled different amounts of remindings. Further, no significant differences were found in category learning in near (Experiment 1) or far (Experiment 2) transfer. Implications for theories of category learning are discussed.
    • Scalable Block Gibbs Sampling for Image Deblurring in X-Ray Radiography

      Morzfeld, Matthias; Luttman, Aaron B.; Adams, Jesse John William; Kennedy, Thomas G.; Lin, Kevin (The University of Arizona., 2019)
      Quantitative image analysis in the security sciences formulates an image deblurring problem as a Bayesian inverse problem to reduce and quantify noise and blur. We consider images of size 16 megapixels and, since each pixel represents an unknown, the dimension of the Bayesian inverse problem is on the order of 107. The large dimension poses numerical and computational difficulties for two reasons. First, Markov chain Monte Carlo (MCMC), typically used to solve a Bayesian inverse problem, is generally slow to converge in high dimensions. Second, even generating one step in a Markov chain is challenging at this size. We present a Gibbs sampler that is scalable to the large dimension required in the security sciences and its scalability is achieved in two steps. We (i) accelerate MCMC convergence by exploring banded structure in the posterior precision matrix; and (ii) use a matrix-free implementation, because constructing and storing even sparse matrices is infeasible in our target application.
    • Development of a Widely Tunable All Fiber Laser Source for Raman Spectroscopy/Microscopy

      Kieu, Khanh K.; Crystal, Sean Owen; Jones, Jason; Su, Tsu-Te Judith (The University of Arizona., 2019)
      Raman microscopy is an important tool for a variety of applications, but the current laser sources used for this technology make the availability of these systems uncommon. Current laser sources are simply too complicated and expensive, taking up the footprint of an entire optics table and costing up to $500,000. There is a strong need for a simpler laser architecture which can still meet the resolution and tunability requirements of current systems. In this thesis, I describe the progress made toward developing such a laser source in the Ultrafast Fiber Lasers and Non-Linear Optics group and the College of Optical Sciences. We demonstrate promising performance results and identify areas of improvement that will soon enable our group to have a high performing Raman microscope.
    • Switched-Beam 60 GHz Endfire Circular Patch Planar Array With Integrated 2-D Butler Matrix for Chip-to-Chip Space-Surface Wave Communications

      Melde, Kathleen L.; Baniya, Prabhat; Dvorak, Steven L.; Roveda, Janet M. (The University of Arizona., 2019)
      The complexity of chip interconnection on a multicore multichip (MCMC) module using the traditional wired interconnects increases with the chip count. The global wired interconnects that run across the entire module must be made longer as more chips are placed on a larger module. Since the interconnect delay grows as the square of the interconnect length, the global wired interconnects can become a major bottleneck of the computing performance in such systems. This dissertation presents a new type of hybrid space-surface wave interconnect (HSSW-I) using 60 GHz switched-beam antenna arrays to provide high-speed communication between the chips. The antennas communicate at near the speed of light through radiation in the air above the chips and through surface waves at the air-dielectric interface, and thus avoid lengthy delays. Each array consists of four center-fed circular patch elements with side vias in a 2 × 2 planar grid arrangement. The arrays enable multi-gigabits-per-second (Gbps) reconfigurable interchip communication when integrated with the proper chip transceivers. The main beam of the array is switched in the horizontal plane containing the chips, by changing the interelement phase shifts. The switching of the main beam is analyzed and verified through full-wave simulation. A compact two-dimensional (2-D) Butler matrix feed network is designed, implemented, and integrated with the circular patch planar array. The matrix is a four-input, four-output, i.e., 4 × 4 network consisting of four interconnected quadrature (90°) hybrid couplers and allows endfire scanning of the array main beam along the four diagonal directions in the horizontal plane. The realized antenna module is a thin multilayer microstrip (MS) structure with a footprint small enough to fit over a typical multicore chip. The antenna module provides a seamless and practical way to achieve reconfigurable interchip communication in MCMC systems. A multiantenna module (MAM) consisting of five antenna modules that emulates diagonal interchip communication in MCMC systems is fabricated. The simulation and measurement of the transmission coefficients between the antenna modules on the MAM are performed, and the signal-to-noise ratio (SNR) and signal-to-noise-plus-interference ratio (SNIR) of the links are calculated. A link decomposition simulation technique to determine the relative contribution of space and surface waves is also applied. A transmission link model is devised based on the leaky wave effect shown by the antenna arrays and the model coefficients are determined from the simulation data. The link model is then extrapolated at various distances and compared with more measurement and simulation results for verification. Finally, realistic link budget calculations are performed based on the measured and simulated data. The calculations show that the antenna modules using the HSSW-I can achieve raw data transfer rates up to 42.24 Gbps at 20 mm distance with low bit error rates (BERs) in the absence of interference, when used with the state-of-the-art 60 GHz complementary metal oxide semiconductor (CMOS) transceivers.
    • Drivers of Carbonate Accumulation in the Cordones Fanglomerate

      Rasmussen, Craig; Agenbroad, Brian Peter; Schaap, Marcel; Crimmins, Michael (The University of Arizona., 2019)
      The accumulation of pedogenic carbonates is important to understanding carbon cycling, to include carbon sequestration, in arid and semi-arid regions. Carbonate accumulation in southern Arizona displays significant spatial variation, particularly in alluvial deposits that dominate basins in the region. Improved understanding of the controls on pedogenic carbonate accumulation is needed. Here it is hypothesized that carbonate accumulation in alluvial fans is controlled significantly by parent material composition. To address this hypothesis, samples were taken from a chronosequence consisting of multiple buried horizons and carbonate accumulations. Parent materials include calcareous and non-calcareous meta-sedimentary rocks, diabase, granites and schist. Measurements included carbonate concentration using a traditional method of hydrochloric acid digestion. This was compared to results generated with an infrared spectral curves for calcium carbonate concentration. Bulk elemental content was obtained via X-ray fluorescence analysis for quantification of immobile element accumulation. Pedogenic iron contents extracted by both sodium dithionite and ammonium oxalate, were taken as indicators for changes in weathering. Results indicate that a mix of eolian material and calcareous rocks are the dominant sources of carbonate accumulations.
    • Exploring the University Support Networks of First-Generation Undergraduate Students

      Rice, Amber; Encinas, Ericka Ruby; Torres, Robert; Mars, Matthew (The University of Arizona., 2019)
      The central research questions that guided this study were: how does the mentor/mentee relationship between academic advisors and first-generation college students develop within an academic success course; how does the mentor/mentee relationship between peer mentors and first-generation college students develop within an academic success course?This research was conducted utilizing a case-study approach with a single academic success course for students on academic probation serving as the case. Three academic advisors teaching the course, four peer mentors meeting with students outside of class, and three students taking the course were interviewed. The case was selected to explore in depth the complex system of support first generation college students receive at the university level. The two overarching themes that emerged from the data were: the process of developing an emotional connection to create a relationship and utilizing a holistic approach to support students. More specifically, finding common ground, being relatable to students, showing that you care for students as individuals, and fostering openness and informality in relationships were the components identified by participants to foster emotional connection. The data also revealed that peer mentors and advisors were initiating accountability with their students, making intentional referrals for students to other campus resources, and the underlying motivation to serve in these two roles came from an intrinsic desire to give back. Recommendations included directors of advising and student retention administrations defining the roles of advisors in regard to student emotional support, compensating them for their work, and increase training for all university staff and faculty on how to create these impactful relationships with students.