• A Comparative Study of Broadcast and Print Coverage in Three Criminal Cases

      Hudson, Lisa Rae (The University of Arizona., Not availa)
    • Liberation: The Story of a French Daily

      Herrera Cruz, Ignacio (The University of Arizona., Not availa)
    • Formative Assessment: Documenting Motor Vehicle Crashes and Local Perceptions with the Hualapai Tribe to Inform Injury Prevention Recommendations

      Mahal, Zeenat (The University of Arizona., 2020)
      Background: This research was designed to understand factors influencing Motor Vehicle Crashes (MVCs) on or near the Hualapai Tribe’s reservation in northwestern Arizona. The goal is to enable the Tribe to develop and implement a locally relevant MVC intervention program. The specific aims were to: i) compile and analyze 2010-2016 MVC data from Hualapai and federal sources to assess distributions of frequency, rates, high risk-locales, causes, days, times, age and sex of the drivers, in addition to assessing related conditions; ii) document local perceptions of environmental, social, and behavioral barriers to safe driving practices, and knowledge of MVC risk factors and existing tribal laws; and iii) provide evidence-based recommendations using the results from quantitative and qualitative data analyses. Approach/Methods: The research process applied a Community-Based Participatory Research approach and mixed methods using: a) secondary data analyses of records from six tribal programs and Indian Health Service (IHS), and b) qualitative analyses of data from two focus groups and field documents. Sensitivity analyses were conducted of IHS and Tribal Driving Under the Influence (DUI) data, using the 2010 U.S. Census as the denominator after adjusting for an undercount of up to 25%. Descriptive statistics, Fisher’s Exact Test, and linear and logistic regressions were used to examine significance. MVCs per 10 miles per year were estimated for State Route 66 and Diamond Bar Road/Grand Canyon West on or near the reservation due to higher numbers of crashes. Statistical process control charts, especially g-charts monitoring time between events, were plotted to examine the stability in the number of MVCs over time for each road. NVivo11Pro© was used to code and analyze the focus group data, guided by both inductive and deductive theories. Results: Driver’s seatbelt use in the Hualapai community increased from 2010 to 2012 (p < .0005), and reported DUIs decreased from 2010 to 2016 (p = .027). Similarly, car/booster seat use improved from 2014 to 2015 (p < .0005). Two hundred and fifty (N = 250) MVC-related injuries were registered at IHS facilities for Hualapai community members between 2006 and 2015. The highest rate, 22.4%, was observed in 15- to 24-year-olds, followed by 21.6% in 55- to 64-year-olds. For several combinations of numerators and denominators, sensitivity analysis of the IHS data shows a clear disparity between the Tribe’s MVC rate compared to the 2008 U.S. rate of 771.4 nonfatal injuries per 100,000 persons and the national goal for Healthy People 2020 (694.3 nonfatal injuries/100,000 persons). The major themes emerged from qualitative analyses of the focus groups were: i) unsafe traffic infrastructures, ii) DUI, iii) repeated DUI offenders driving on the reservation, and iv) a perception of lenient tribal traffic laws and enforcement on the reservation. Using study results, five Public Service Announcements were co-developed to inspire community-members to continue the trends noted from 2010-2016 and be aware of continued risks. Conclusions: MVCs are a multidimensional issue needing communitywide awareness of the range of risk factors. An intervention that addresses human and structural risks requires an alliance of tribal programs and external partners (e.g., IHS, university, federal, and state). Recommendations: Local recommendations include providing school- and institution-based education about alcohol/alcoholism and DUI consequences, and ongoing culturally and locally relevant communitywide education through the local newsletter and radio station.
    • A Highly Modular Router Microarchitecture for Networks-on-Chip

      Wu, Wo-Tak (The University of Arizona., 2019)
      Advances in semiconductor process technology in the past several decades have brought about an abundance of transistors that can be fabricated on a single silicon die. Microprocessor designers have been integrating more and more processing cores on-chip by taking advantage of such abundance. Network-on-Chip (NoC) has become a popular choice for connecting a large number of processing cores in chip multiprocessor designs. NoC provides many advantages over the traditional bus-based approach in terms of bandwidth, scalability, latency, etc. The central part of an NoC is the router. In a conventional NoC design, most of the router area is occupied by the buffers and the crossbar switch. Not surprisingly, these two components also consume the majority of the router’s power. Most of NoC research has been based on the conventional router microarchitecture in the areas of routing algorithm, resource allocation/arbitration, buffer design, etc. There has not been much work done on drastic router microarchitecture redesign. In this dissertation, a novel router microarchitecture design is proposed, which we call Omega, that treats the router itself as a small network of a ring topology. Omega is highly modular and much simpler than the conventional design. It does not use a large crossbar switch as in the conventional design; packet switching is done with simple muxes. Furthermore, the network packet latency is greatly reduced. Simulation and circuit synthesis show that the Omega microarchitecture can reduce latency, area and power by 53%, 34% and 27%, respectively, compared to the conventional design. The Omega microarchitecture design also provides opportunities to implement features that do not exist or are difficult to be realized in the conventional design. To demonstrate this, we implement a new feature on the Omega router to merge packets together in the buffer. The merged packets traverse the network together as long as their routes to destinations do not diverge. This greatly improves the buffer and link utilization. As a result, the effective network capacity can be substantially increased. This dissertation presents one of the first efforts on the new microarchitecture for router considering packet merging. Additional characterizations can be done to better understand its potentials for various applications, and perhaps its shortcomings, in future work to push performance even further.
    • Exploring Non-Psychiatric Nurse Attitudes, Knowledge Base and Comfort Level in Caring for Patients with Mental Illness

      Gutierrez, Christina (The University of Arizona., 2019)
      Background: Mental health disorders can be perceived as threatening and uncomfortable to non-psychiatric nurses who may have limited education and/or specialized training on mental health conditions. Due to lack of specialized psychiatric knowledge and training, non-psychiatric nurses develop attitudes that are based on misperceptions such as the fear that mental health patients are aggressive and violent. These perceptions contribute to discriminatory acts by the nurses and heightened stigma. This fear also induces a sense of caution and guard (which in turn interferes with their ability to be effective nurses) due to a perceived threat on their own safety. Objective: Explore nurse attitudes, knowledge base and comfort level of non-psychiatric nurses caring for the patient with mental illness through the use of a pre-existing Likert scale (MICAv4) and a newly developed semi-structured survey (Demographic & Knowledge Base Questionnaire [DKBQ] administered through an online Qualtrics survey. Design: Descriptive quality improvement design. Setting: Medical/Surgical unit in a 212-bed not-for-profit community hospital in the East Valley of the Phoenix Arizona metropolitan area. Participants: Non-psychiatric nurses on the inpatient medical/surgical unit whom care for psychiatric patients and are employed by the community hospital, in Arizona. Results: 60% of the nurses interviewed feel comfortable caring for patients with a psychiatric disorder, 57% feel they have adequate knowledge of psychiatric medications, and 67% feel they have adequate knowledge of psychiatric disorders. In regards to attitudes, 71.4% of the nurses interviewed overall disagree that people with a severe mental illness can never recover enough to have a good quality of life, 62% of participants disagree the public does not need to be protected from people with mental illness, and more than half agree they feel comfortable talking to a person with a mental illness the same as talking to a person with a physical illness. Conclusion: Overall, the nurse participants indicated feeling a baseline comfort in caring for patients with a mental illness. More than half feel they have adequate knowledge of psychiatric disorders and psychiatric medications. The participants, attitudes per the MICAv4 scale indicated the participants have a reduced stigmatic attitude in caring for psychiatric patients.
    • Études for the Orchestral Cymbalist: Developing the Skills for Successful Crash Cymbals Performance

      Timman, Matthew Peter (The University of Arizona., 2019)
      In the study of percussion instruments as a part of a collegiate education, the focus is usually placed upon performance of literature from four major areas: snare drum, mallet percussion, timpani, and multiple percussion. This often leaves an instructional gap in the field of performance on percussion accessory instruments, including performance of orchestral crash cymbals. Though literature exists for the instruction of techniques required for commonly performed orchestral works and collections of basic études for cymbals, currently no pedagogical literature exists that cultivates the techniques required for performance of standard orchestral literature through technical études. By identifying required techniques for the performance of standard orchestral literature, technical études have been composed in order to assist with the development of six essential core techniques required to perform the most widely performed orchestral repertoire and works requested in professional orchestral auditions. In addition to these technical études, accompaniment tracks have been composed, incorporating music from the original orchestral works to help educate performance and cultivate a greater familiarity with the repertoire for which the études are specifically designed.
    • La Verdad Cómica: Rius, La Contracultura Mexicana, y Una Ficción Fundamental No Oficial

      Howard, Sarah E. (The University of Arizona., 2019)
      Eduardo del Río (known as Rius) proved a fierce political activist and prolific comic book creator. He challenged the successes of the Revolution, exposed weaknesses in the government, and provided a voice willing to say something aloud. Unlike most in the comic book industry, del Río held strong leftist political inclinations and campaigned against, among other things, the Institutional Revolutionary Party, U.S. policies in Mexico, and the Catholic Church. Comic books, along with other forms of popular culture, hold an important role in the cultural identity of the nation’s people. Del Río’s work became a part of the continual comic book exchange of its period. His series, Los supermachos (1967-1981) and Los agachados (1968-1977), solidified his role in national identity construction. Comics hold a place in cultural memory and identity construction far more lasting than the inexpensive paper they are printed upon. It is in part because of the persistent nature of comics that an eighty-three-year-old virtual recluse could be considered not only culturally relevant but esteemed. There is no correct way to study popular culture. The closest a scholar can come is to approach the topic openly and from all directions. Popular culture derives power from its fluid, ever-changing, unmeasurable nature. A close study of the work of a man who challenged the status quo provides entry into a field of study that itself questions hundreds of years of history awash in timelines, memorized dates, and military history. Pick up a comic book and dive into the possibilities.
    • Rhetorics of the Fantastic: Re-Examining Fantasy as Action, Object, and Experience

      Rick, David Wesley (The University of Arizona., 2019)
      Establishing the literary genre of fantasy, as it is currently known, is largely credited to J. R. R. Tolkien in the mid-twentieth century, though in a broader sense fantastical storytelling has existed for as long as humans have been telling stories. Since its rise to popularity as a contemporary genre, many scholars have studied fantasy in various dimensions, but such study has tended to emphasize genre taxonomy, remaining otherwise generally limited in scope and narrow in focus. This dissertation seeks to complicate an understanding of the term “fantasy,” particularly as it differs from commodified, market-driven genre conventions. It argues that the fantastic represents departure, transformation, and alternative modes of thinking. The project examines major writings on fantasy and the fantastic, including works by writers such as Tzvetan Todorov, Farah Mendlesohn, Ursula K. Le Guin, and Tolkien. It also examines how the fantastic manifests in works not usually thought of as fantasy, as in the writings of Gloria Anzaldúa, and draws upon rhetorical thinkers, such as Wayne Booth and William Covino, while borrowing Kenneth Burke’s dramatistic pentad as a central device to establish a “fantastical pentad.” Part One of this dissertation examines three major capacities of this fantastical pentad: action, object, and experience. As action, the fantastic has the power to complicate, to reimagine—what Tolkien called “sub-creation” and what Paulo Freire called “re-creation.” This produces a fantastical object, or fantasy, that embodies the transformative power of the fantastical act, allowing others to experience it. In turn, experiencing a transformative fantasy offers the opportunity for questioning, evaluating what that fantasy is, how it may or may not be plausible within one’s worldview, and to understand why it is fantastical—that is, what it seeks to transform. Part Two applies these ideas to three sites of inquiry: the composition classroom, games and play, and popular fiction. The project concludes that the fantastic offers, as its primary function, not escapism or mere “flight of fancy,” as has often been claimed in the past, but transformation. This transformation may work in many ways: it may be transformative for the fantasist, who enacts the fantastic; it can be transformative for the audience, who experience the fantasy that the fantasist creates; or, it can be transformative within the object, itself, by reimagining some convention within the writing. This compositional transformation may be a narrative element of fiction such as in the works of Le Guin, where the fantasy is transformative within its genre, or in the writing of Anzaldúa, which blend the fantastic with non-fiction for very material, real-world purposes. This illustrates a cultural significance that reaches far beyond the realm of idle entertainment, providing inspiration and impetus to enact change in the material world.
    • Bifacial Solar Panels System Design, Modeling, and Performance

      Ayala Pelaez, Silvana (The University of Arizona., 2019)
      Bifacial photovoltaic (PV) cell technology is currently poised to change solar modules and systems. They provide higher energy yield from its ability to capture both direct and diffuse illumination on the front- and rear-side of the module. At low-costs for implementation in production lines of traditional monofacial silicon cells, lower maintenance needed in fields compared to a similar power array of conventional modules, improved module characteristics like lower thermal coefficient due to better (in average) processes used in production, the implementation of this technology is projected to have a significant impact in the reduction of the cost of solar power, adoptable in a short period of time. Bifacial technology promises even lower $/W and $/kWh costs, continuing to improve solar photovoltaics’ competitive cost with fossil fuel energy sources and help mitigate climate change. However, bifacial PV performance models are not well established, and field validation data is scarce. Furthermore, existing optical models used to calculate the irradiance input into the modules make certain assumptions that have not been scarcely verified. This dissertation performs a study of these optical models for calculating irradiance available to bifacial panels under different deployment configurations. Sensitivity to mounting parameters and modeling assumptions are explored. The models agree between 2-3% despite differences in assumptions and complexity. The results from a test-bed built to validate the optical models are shown, showing good agreement within 2% error (absolute) in the bifacial gain in irradiance. Furthermore, algorithms for bifacial PV modules with single-axis tracking are implemented and presented. Field-data from two locations with single-axis trackers with monofacial and bifacial PV module technology are used to validate the algorithms. A methodology for calculating bifacial gain due to the fact that they can accept light from both front- and rear-side (a property known as bifaciality), and not due to differences in other cell or module properties, is also presented. This methodology has the possibility of addressing the lack of a framework for reporting bifacial versus monofacial fields gains, which has resulted in a wide range of reported gains. The methodology is used to compare performance data for two 100kW bifacial and monofacial arrays in Klamath Falls, Oregon, finding that 2.4% of the measured performance advantage of the bifacial array is due to improved front-side performance, rather than bifacial response. This dissertation concludes with the design of an optical concentrator to improve the specific uses of bifacial PV modules for vertically-mounted systems. Discussion of areas for improvement and future work are also included.
    • Compassion Fatigue among Pediatric Oncology Nurses

      Cooper, Jessica (The University of Arizona., 2019)
      Purpose: To conduct an educational intervention to improve knowledge about compassion fatigue among pediatric oncology nurses at Phoenix Children’s Hospital (PCH). Background: Burnout, secondary traumatic stress, and decreased compassion satisfaction contribute to compassion fatigue. Pediatric oncology nurses face stressful situations based on the unique care demands of children battling cancer such as complex treatment regimens, managing professional boundaries, providing emotional support. grief, and bereavement. Compassion fatigue is a progressive process that can impact a nurse’s quality of life and contributes to decreased job satisfaction, performance, patient satisfaction, and turnover. Methods: A 20-minute educational PowerPoint presentation was presented on compassion fatigue to highlight what compassion fatigue is, signs and symptoms, and common triggers. There was also a handout provided with available resources at PCH that could be utilized to help with compassion fatigue. The Professional Quality of Life (ProQOL) scale was used to measure compassion fatigue and compassion satisfaction levels and a pre- and post-test was completed to measure if an educational intervention improves nurse’s knowledge about compassion fatigue. Findings: The results showed that participants (n=30) knowledge significantly improved after the 20-minute educational intervention (p=0.001) with a mean score of 76.2% on the pre-test and a mean score of 95.4% on the post-test. In addition, nurses had a significant increase (p=0.0001) in the utilization of resources; prior to the intervention only seven participants (23.3%) utilized some of the available resources offered by PCH compared to 24 participants (80%) one-month post-intervention. However, there were no statistically significant changes in raw scores for the pre- and one-month post ProQOL survey (p > 0.05). Overall the participants viewed the class worthwhile and had positive things to say about the class. Implications: The results of this study showed that an educational intervention on compassion fatigue improved nurses knowledge about compassion fatigue, symptoms, common triggers, and available resources with improved utilization of available resources. Even with improved knowledge and utilization of resources, there was not a statistically significant difference in pre- and one-month post survey scores on compassion satisfaction, burnout, and secondary traumatic stress. Future research could benefit from analyzing the long-term effects improved knowledge of compassion fatigue and the utilization of resources has on compassion satisfaction and fatigue.
    • Evaluating Healthcare Providers’ Utilization of Social Support for COPD Patients

      Nguyen, Thiennga (The University of Arizona., 2019)
      Background: Currently, most primary healthcare providers manage chronic obstructive pulmonary disease (COPD) through pharmacological treatments, often lacking assessment of the patient’s social support. A lack of social support negatively impacts the quality of life (QOL) of individuals with COPD resulting in increased morbidity, hospital readmissions and excessive costs (Metting, van der Molen, & Kocks, 2016). A comprehensive approach extends beyond pharmacological management to include ways that improve patients’ disease knowledge and self-efficacy, resulting in better disease management and improved QOL. Aim: The purpose of this quality improvement (QI) project is to increase healthcare providers’ understanding of the importance of adding a social support referral as part of a comprehensive treatment for patients with COPD. Methods: The QI project was conducted at Banner Desert Medical Center in Mesa, Arizona. The targeted participants were registered nurses, case managers, social workers, and any other care providers in telemetry units, where most COPD patients are treated. The project included a pre- and post-test survey questionnaire and a brief PowerPoint educational presentation. The presentation showed the positive role of social support groups for COPD patients based on multiple evidence-based studies and introduced several options of social support groups to the participants. Results: Total number of participants who completed the project were 42 (n=42), and included registered nurses, one case manager, and one social worker. Most of the participants were not aware of the existence of any social support group before the educational presentation. After the presentation, the collected data demonstrated increased participants’ knowledge and attitudes about the social support groups and the participants’ willingness to utilize the social support referral as part of a comprehensive education and treatment for COPD patients. Conclusion: The referral of social support program is a cost-effective intervention. As shown in several evidence-based studies, the benefits are endless when integrating the referral of a social support group, such as the Better Breathers Club, into COPD patients’ education and discharge planning, so that the patients themselves can connect, share their experiences, learn to better cope with the disease, improve their knowledge and self-care and reduce their depression, exacerbation, and hospital readmissions.
    • Improving Use of Opioid Safety in Primary Care

      Fisher, Kristen (The University of Arizona., 2019)
      With an increase in opioid prescription rates, opioid misuse, abuse and overdose deaths have increased in parallel. Primary care providers are responsible for the majority of the system’s pain management but may lack proper training. The purpose of this project was to implement an educational module designed to improve primary care providers’ knowledge about unnecessary opioid prescriptions, safe pain management and opioid related disorders. This project implemented an educational module to familiarize primary care providers with evidence based guidelines for prescribing opioids for chronic pain management. This project used a pretest-posttest design to evaluate if the educational module was effective in increasing provider knowledge. Provider knowledge was assessed using the KnowPain-12 tool and an eight-item survey based on the Center for Disease Control (CDC) guidelines for opioid prescribing. Six providers participated in the educational intervention and responded to the pre and post-survey. For the KnowPain-12 survey, three providers had a higher score following the intervention, one provider’s score stayed the same and two had lower scores. The KnowPain-12 survey score ranges from 0-60, average score of the pre-intervention survey was 39.33 and the average score of the post-intervention survey was 39.50. For the knowledge assessment of the CDC guidelines, one point was awarded to each correct response for a total of eight points possible. Overall scores were high, with an average score of 6.83 before the intervention and 7.5 after the intervention. Findings suggest that there may be an educational gap in chronic pain management for primary care providers. There needs to be further research to evaluate opioid prescribing practices in the primary care setting and to identify educational gaps. Educational interventions should be implemented to improve provider knowledge of chronic pain management.
    • Mind the Gap: Gender Differences in Alcohol Consumption and Protective Behavioral Strategies at a Large Public University, 2002 - 2016

      Salafsky, David B. (The University of Arizona., 2019)
      Alcohol use among college students is a persistent and far-reaching public health issue. While some measures of alcohol use within the college population appear to have improved, questions remain as to whether the alcohol use gender gap has been stable or is in a period of change. Protective behavioral strategies (PBS), harm reduction approaches commonly used to address high-risk alcohol use among college students, were also assessed, to determine their relationship with several key alcohol consumption measures for both males and females. Methods: This research summarizes alcohol-related consumption measures based on annual, cross-sectional survey data collected between 2002 - 2016 at a large, public university. Linear regression models as well as descriptive statistics were used to explain overall trends and gender-specific patterns of use over time. In addition, an analysis based on pooled data between 2013 – 2016 was conducted to determine the association between protective behavioral strategies and key alcohol consumption measures, to inform programming that uses these strategies to reduce high risk alcohol use among students, and determine which strategies may be more likely to benefit either males and females for the following alcohol measures: binge drinking in the past two weeks, average drinks when partying and the number of drinks last time consumed alcohol. Both logistic and linear regression models were used to describe these relationships. Results: The results of the 15-year trend analysis revealed significant and meaningful declines among all students in past 30-day alcohol use, average number of drink consumed in the past week, average number of nights students “party” each week, and reductions in the frequency of binge drinking. Looking at the gender gap specifically, these results showed a declining gender gap (i.e. where the difference between male and female use decreased) most notably in average number of drinks consumed in the past week, estimated BAC last time students drank, and past 30 day alcohol use. Based on recent survey results, women showed slightly higher past 30-day alcohol use and reported a higher estimated BAC last time they drank, compared to men. For the second aim of the study, which was based on pooled data collected between 2013 - 2016, most PBS that were expected to moderate alcohol use showed clear and strong protective effects, with a few exceptions. Top strategies for females that were associated with lower alcohol consumption included stopping alcohol use 1-2 hours before going home, avoiding pre-partying and avoiding hard liquor. For men, these included setting a limit on drinks, avoiding pre-parting, and avoiding hard liquor. Conclusion: A number of alcohol measures improved during the study period, and for these, male university students showed greater declines, on average, than females – resulting in a shrinking gender gap. Decreases in the frequency of drinking occasions likely influenced overall declines in average drinks per week and the frequency of binge drinking. Male and female students showed considerable overlap with respect to protective behavioral strategies that were negatively associated with alcohol use and identified a few strategies that may have limited effectiveness. These results highlight evolving trends in alcohol use among college students and point to specific strategies which can help address this longstanding public health issue. Policy and program recommendations, informed by these findings, are detailed in its conclusion.
    • Facebook pages and public spaces: Guatemala's 2015 movement and the years that followed

      Chikos, Michael (The University of Arizona., 2018-01)
      Guatemala’s 2015 Summer demonstrations were the largest public protest in the country since the Guatemalan Spring in 1944. These demonstrations were organized rapidly via social media, with Facebook Pages in particular playing a vital role, making them comparable to other digital mediated social movements and new forms of social protest in Latin America. The aims of this study are to explore the role of Facebook Pages in this historic moment, through an approach that considers both the cultural and political impacts of new technologies. Since the 1960s an emerging discourse around “New Social Movements” emphasizes the communicative and ideological nature of social movements, in contrast to social movements that seek purely political aims. This research found that while the Facebook Page should be understood as a Public Space where cultural forms are challenged and reshaped, it is also a highly political technology with real world effects.
    • A Structured Approach to Training Text Messaging in an Individual with Aphasia

      Fein, Mira (The University of Arizona., 2018)
      Background: Text messaging is an increasingly common communication modality that can present considerable challenges to individuals with aphasia. Not only does “texting” rely on central (linguistic) and peripheral (sensorimotor) abilities, it requires unique procedural and pragmatic skills. Aim: The purpose of this study was to develop and evaluate a structured treatment protocol to promote mastery of communication via text messaging in an individual with aphasia. Methods: This exploratory study with a 72 year-old woman with anomic aphasia and mild limb apraxia extended language treatment to target technical and pragmatic skills for mobile phone use. Beginning three years post stroke, she received a three-phase training sequence that first addressed single-word typing on her mobile phone, followed by script training for text messages, and finally conversational skills for initiating and responding to text messages. Results: Despite some residual language and visual processing impairments, the participant developed functional text messaging abilities at the word, script, and conversational levels. She demonstrated generalization of skills to novel content and situations, and maintained her text-messaging abilities one year post-treatment. Conclusions: The treatment protocol to retrain text messaging skills in an individual with aphasia yielded strong positive outcomes, warranting further examination in other suitable individuals.
    • Liquefaction of the Brain Following Stroke Shares Multiple Characteristics with Atherosclerosis and Mediates Secondary Neurodegeneration in an Osteopontin-Dependent Mechanism

      Chung, Amanda (The University of Arizona., 2018)
      The response to ischemic injury in the brain is different to the response to ischemic injury in other organs and tissues. Almost exclusive to the brain, and for unknown reasons, dead tissue liquefies in response to ischemia by the process of liquefactive necrosis. However, the data we present here indicate that at the macroscopic, microscopic, and molecular level, liquefactive necrosis strongly resembles atherosclerosis. We show that chronic stroke infarcts contain foamy macrophages, cholesterol crystals, high levels of osteopontin and matrix metalloproteases, and a similar cytokine profile to atherosclerosis. Crystalline cholesterol is a principal driver of atherosclerosis, and because cholesterol is an important structural component of myelin, we propose that liquefactive necrosis in response to stroke is caused by an inflammatory response to myelin debris, and is exacerbated by the formation of cholesterol crystals within macrophages. We propose that this leads to the chronic production of high levels of proteases, which in a partially osteopontin-dependent mechanism, causes secondary neurodegeneration and encephalomalacia of the surrounding tissue. In support of this, we show that genetically ablating osteopontin substantially reduces the production of degradative enzymes following stroke, reduces secondary neurodegeneration, and improves recovery. These findings suggest that treatments that prevent or target the regression of atherosclerosis may also be useful for mitigating the harmful effects of liquefactive necrosis following stroke.
    • Linking Net Assimilation with Multispectral Vegetation Classification to Understand Mesquite-Grass Response to Fire

      Sutter, Leland Frederic (The University of Arizona., 2018)
      Understanding vegetation dynamics across space and time has been a grand challenge in Earth sciences, but the induction of remote sensing products has made large-scale mapping of vegetation possible. We initially used Landsat satellites (30 m; eight-day return interval) to assess the Sawmill Fire of 2017 within the Santa Rita Experimental Range. Because of the spatial and temporal decoupling associated with this remote sensing product, important, but smaller-scale disturbances may not be properly captured; this prompted the use of finer scaled data. As such, we used an unmanned aerial vehicle (UAV) equipped with a five band Micasense RedEdge camera for derived land classification and scaling. Additionally, we measured leaf level net assimilated photosynthesis (ANET) to quantify plant function. We repeated the measurements at three points in time at a control and burned site. Spectrally, changes in the Relative Normalized Burn Ratio (RNBR) using Landsat images from directly before the fire and then after the growing season showed minimal evidence of the fire because of its spatial scale, though there were significant impacts from the fire on vegetative physiognomy and ecosystem function. Classifications built from the multispectral camera showed an overall accuracy of 0.89. This study shows the need for fine-resolution data from newly available UAV systems for practical land management practices. Low altitude, fine resolution data, combined with ecophysiological datasets, can be used to quantify and follow tractable land cover changes not captured by our traditional, lower resolution remote sensing sensors and derived products.
    • The Pathophysiology of Chronic Stroke Infarcts: What Happens After Brain Tissue Dies?

      Likens, Jacob Andrew (The University of Arizona., 2018)
      A stroke can occur when blood flow to a specific area of the brain is interrupted. There has been extensive research in both animal models and humans that has characterized the pathophysiology of the first few weeks following stroke. However, there has been far less research into the chronic stage of infarction. This is an important area for research because more than 10 million individuals worldwide suffer a stroke each year. Approximately one-third of these survivors develop dementia in the first year after their stroke. The cause behind this dementia is currently unclear, and there are no neuro-protective drugs that can improve recovery and provide cognitive protection in the chronic time period. Therefore, the chronic stage of stroke recovery is a promising target for future therapeutics for stroke-related dementia and, as will be shown later in the paper, Alzheimer’s disease as there are likely to be neurodegenerative processes that proceed for months following stroke. The goal of this thesis is to provide a review of what is currently known about the pathophysiology of chronic stroke infarcts (an area of brain tissue that has necrotized due to a blockage in an artery in the brain causing a lack of oxygen), explain why so little is known, and how we can learn more, and provide potential mechanistic links between the response to dead brain tissue and the development of dementia.
    • Mapping Saguaro Cacti Using Digital Aerial Imagery in Saguaro National Park

      Carter, Forest (The University of Arizona., 2018)
      The saguaro cactus has been the subject of extensive ecological research since the establishment of Saguaro National Monument in 1933. Saguaro mapping and monitoring has always been limited in extent due to inherent restrictions of in situ field methods. This research developed a method for automated mapping of mature saguaros over large extents using fine spatial resolution digital aerial imagery. Saguaro shadow signatures were identified using a novel contrasting custom search kernel method. The shadows detected were used as proxies for mature saguaro locations. This research focused on (1) the development of a method of automatically identifying saguaros using their shadows in aerial imagery, (2) applying the method to aerial imagery of Saguaro National Park (SNP) to conduct a large extent saguaro census, (3) validation of the saguaro distributions against in situ field measurements, (4) investigating causes of shadow omissions, (5) estimating total saguaro densities and populations in SNP. The shadow method developed identified 446,092 saguaros across 231 square kilometers in Saguaro National Park. These results were found to be highly correlated (R2 value of 0.966) with saguaro locations recorded by SNP staff in 11 field plots in 2011. This study demonstrates that mature saguaros can be reliably mapped automatically using digital aerial imagery. The method developed will facilitate saguaro monitoring and ecological resource management in SNP and throughout the range of the saguaro cactus.