Now showing items 1-20 of 14548

    • Seedling Survival in a Variable Environment: Connecting Physiology Across Life Cycle Stages

      Basinger, Ursula Nani (The University of Arizona., 2018)
      Seedling establishment is a crucial phase when plants are particularly vulnerable to environmental stress. Nonetheless, seedling traits and survival are rarely studied in functional ecology. Using five common species in a well-studied guild of desert annuals, I measured seedling survival and functional traits in response to drought under three temperature regimes in growth chambers that spanned the range of temperatures seedlings normally experience during the germination season. I compared seedling longevity and growth rates to a suite of previously measured plant traits to determine how seedling responses to temperature and drought correspond to physiology at other life cycle stages, as well as to long-term patterns of seedling survival in the field. Generally, seedlings of all species survived longer in cooler temperatures. However, some seedlings had limited early mortality prior to drought conditions, especially in colder temperatures. Temperature-dependent patterns of survival were strongly related to traits expressed at different points in the life cycle, including seed size, germination and, to a lesser extent, growth traits, indicating coordinated functional strategies. Species with larger seeds, faster germination and higher water-use efficiency survived drought longer, especially in the colder temperature. Seedling survival in the growth chamber was correlated with seedling survival rates in the field. Neither relative growth rate nor specific leaf area plasticity under experimental drought conditions connected meaningfully to other functional traits and further research is needed to determine how seedling growth under stress relates to these traits. This study is the first to show that temperature-dependent seedling survival under drought conditions covaries with functional strategies across the lifecycle and predicts natural patterns of establishment in the field.
    • Analysis of 3-D Seismic Data from Block 3 in the Lower Congo Basin, Offshore Angola

      Mateta, Nelson (The University of Arizona., 2018)
      The Lower Congo Basin (LCB) is a rift basin located in the passive margin of Angola that resulted from the rifting of Gondwanaland, which led to the separation of the Angolan plateau with the South American plate during the Early Cretaceous 144-140 MA. The basin extends over 600 km between 5°S and 8°30’S of latitudes, and it is constrained by Casa Maria Arch to the north and Ambrizete Arch to the south. The basin has undergone pre-rift, rift, and post-rift tectonic phases associated with subsalt, salt, and supersalt units driven by thermal subsidence, extensional updip complex systems, and Aptian compressional salt downdip systems. The area of study is located in the southern part of the LCB, offshore Angola. It has a complex geologic context with a petroleum system comprised of shales, carbonates, and turbidites deposited into marine and deltaic environments. Moreover, regional anticlines and half grabens containing syn-deformational strata have been associated with the LCB. However, the area of study lacks detailed structural and petroleum system analysis. The main focus of this research is to provide a general structural and petroleum system characterization of the area of study based on 3-D seismic reflection and well data provided by the Angolan oil company Sonangol EP. The well data was used to assess possible areas of interest as well as to create a synthetic seismogram that was used to tie the well to real seismic data; meanwhile, the seismic reflection data was used to track reflections of interest, map faults, create surface and isopach maps, extract seismic attributes, and evaluate seismic facies. In addition, the 3-D seismic data was also used to map unconformities and a large anticline bounded by half grabens and listric and planar normal faults.
    • Politicking While Black: News and Social Media Representations of Three Black Female Political Candidates Running for the House of Representatives in the 2018 Midterm Election

      Cabrera-Peterson, Zeina Atalig (The University of Arizona., 2018)
      African American women have been the leading force in political campaigns long before they had the right to vote and hold office. Today, roughly 5% of African American woman hold political positions (CAWP, 2018). However, despite their political participation, there are few studies that examine representation of Black female political candidates in news media. This study employed a content analysis of news reports and three Black female candidates' Twitter campaign accounts to examine how news media represented these three, first-time candidates and to analyze how these candidates represented themselves on Twitter. Based on the overall analysis of a census of newspaper articles and Twitter candidate accounts, the study found that race and gender was not a leading area of news coverage or self-representation in tweets. The research found that these candidates were mostly identified by their former occupations and were not questioned because of who they are, but because of what they do. These findings are significant because it challenges and reshapes gender and race identities.
    • Frailty and Voice: Acoustic Analysis of Connected Speech in Single- and Dual-Task Conditions

      Monti, Sara (The University of Arizona., 2018)
      The objective of this study was to compare six acoustic measures of speech and voice production in connected speech samples to determine whether the voices of adults who are frail differed from those adults who are not frail or are borderline frail, and whether cognitive dual-task interference induced more changes in voice quality for those who are frail than participants in the other two groups under the same conditions. A controlled, cross-over, quasi-experimental research study protocol was implemented, in which participants were grouped according their overall frailty score on the Fried Frailty Index. Each participant completed two verbal picture description tasks, first in a single-task control condition and then in a dual-task condition with simultaneous sorting of plastic tiles by size. Connected speech samples were analyzed for six acoustic measures: articulation rate, mean fundamental frequency, fundamental frequency variability, intensity range, speech range density profile area, and cepstral peak prominence-smoothed. Both absolute values and a difference score across conditions were used. Performance differences were analyzed with independent sample t-tests and repeated measures MANOVA/MANCOVA, with acoustic measures as the outcomes and task condition and frailty status as independent variables. Model covariates included demographic characteristics and cognitive and communication measures. Exploratory analyses suggest that fundamental frequency variability and SRP area may show some promise for describing characteristic speech production associated with frailty status. Keywords: dual-task interference, frailty, fundamental frequency, fundamental frequency variability, speech range density profile area, voice
    • Obstructive Sleep Apnea and the Gut Microbiome

      Morales, Efreim Joseph Dela Cruz (The University of Arizona., 2018)
      We investigated how the combined influence of intermittent hypoxia (IH) and high-fat diet (HFD)—modelling obstructive sleep apnea (OSA)—can induce gut microbiota dysbiosis and alter host gene expression. The study involved 16 mice randomly assigned to four experimental groups receiving distinct treatments as follows: normoxia-normal diet (NM-ND), normoxia-high-fat diet (NM-HFD), intermittent hypoxia-normal diet (IH-ND) and intermittent hypoxia-high-fat diet (IH-HFD). IH-treated mice were subjected to ten IH cycles per hour (six-minute cycles, first three at 9% O2 and the next three at 21% O2). Mucosa and fecal microbiota were characterized by pyrosequencing of the hypervariable V4 region of the 16S ribosomal RNA and analyzed via Quantitative Insights into Microbial Ecology (QIIME) software package. Host response was analyzed through microarray analysis of colonic genes. Nevertheless, the focus of the experiment’s microbiome and microarray analysis shifted to the proximal colon. Alpha-diversity and beta-diversity analysis of the mucosal and fecal microbiota suggested a more potent impact of HFD on distinct differences in bacterial profile, accompanied by an increase in Firmicute:Bacteroidetes ratio. Bacterial community profiles in the proximal colon were demonstrated to have more significant (p<0.05) dissimilarities in contrast to the distal colon. We found that members of the same taxa behaved differently; more specifically the Peptostreptococcaceae family and the Lachnospiraceae family (both from the Firmicute phylum) grew in abundance on HFD but decreased and increased in numbers, respectively, with the added treatment of IH. Two-way ANOVA on samples calculated that dietary content had the most significant (p < 0.05) impact on gene expression; followed by the combined impact of diet and oxygen status, and then oxygen status alone. Furthermore, gene ontology (GO) analysis revealed significant (p < 0.05) biological functions (ex. cell-to-cell adhesion) while gene set analysis (GSA) further identified the genes (ex. Cldn2, -4 and -15) that may be responsible for regulating these altered processes. Taken together, the combined impact of IH and HFD on the gut microbiota significantly caused dysbiosis on a specific site more than another (proximal colon versus distal colon, respectively), had varied effects on different taxonomic levels and elicited changes on host gene expression involved in intestinal impermeability—playing a key role in immune and metabolic responses that may underlie disease.
    • Changing Times and Domestic Goods: An Investigation into the Organization of Pottery Production in Lerna III and IV

      Roberson, David Buck (The University of Arizona., 2018)
      The Early Helladic II-III (EH II-III) transition was a period of dramatic cultural change in the Argolid, and one of the most prominent shifts which occurred at this time was in the pottery, which changed from forms with few handles, simple decoration, and homogeneous appearances to ones with an abundance of handles, prominent decoration, and wide variation in appearances. While this shift has been explained to some extent by writers such as Rutter (1993) and Spencer (2007), the nature of this change has not yet been fully explored. This thesis explores this problem by examining the organization of pottery production in Early Helladic Lerna, a type site for the region. This is done by examining indirect evidence from Lerna in EH II and EH III, largely through the use of standardization analysis, which is then used to evaluate the organization of pottery production in each phase by using Costin’s parameters of craft production, namely intensity, concentration, scale, and context (1991). These are then compared, ultimately concluding that production was at the level of very low-intensity household production for domestic use and limited non-economic trade in both periods. The single change observed is in the context of production, which is found to move from a midpoint between independent and attached production in EH II to embedded production in EH III, a form of attached production. This occurred as the result of a change from a seemingly uncontested political sphere in EH II to one characterized by competition between individuals or groups in EH III, which caused the political powers to draw nearer to their otherwise unchanged pottery production groups in order to compete for power This thesis contributes to current scholarship in several ways. It first of all provides new evidence for the organization of pottery production in the Argolid during EH II and III, which has received little scholarly attention. It also contributes to research into the nature of the political changes which occurred across the EH II-III transition, such as Weiberg and Lindblom’s suggestion of differential adoption of foreign elements in the Argolid in EH III (2014), which I propose is due to varied approaches to competition for political authority. Finally, it provides a useful instance of shifting political power and an associated change in production context that problematizes typical narratives regarding the development of attached craft production (Costin 1991: 12).
    • Achieving Net-Zero Energy in Primary Schools In the Hot-Arid Region of Makkah, Saudi Arabia

      Noor Wali, Suhaib Eshaq (The University of Arizona., 2018)
      The energy demand in the Kingdom of Saudi Arabia (KSA) is drastically increasing due to the recent Saudi government’s growth and development in multiple fields. Part of the new government’s vision is to create a lower impact of carbon emissions on the atmosphere. Thus, a significant consideration of building energy consumption is crucial since around 78% of the energy consumption is caused by the building sector in KSA. Residential buildings, however, account for 50% of the energy consumption, and government buildings show negligence in their function (Saudi Energy Efficiency Center 2017). Moreover, with the increase in electricity tariffs, the government has forced the operators of its buildings to enhance building efficiency to consume less energy especially in schools. This research aims to study the possibility of Net-Zero energy schools in Makkah, KSA. The purpose is to create an educational icon that educates the new generation about the importance of sustainability through visual interacting in addition to providing a high performance and healthy learning environment for students and teachers. A prototypical elementary school model was analyzed and simulated using eQUEST, an energy software, to determine the different issues that cause high energy consumption in the school. The building model, Al-Muna School, is a 32,400 ft² primary school located in Makkah, KSA, that has a hot-arid climate. The prototype was simulated using eQUEST, and the simulation result was compared with the energy use intensity (EUI) for primary schools in the hot-arid region of USA, which has the same climate zone as Makkah. The prototype was worse than the code for the educational buildings. The author provided recommendations of passive and active environmental strategies to mitigate energy use in the school building including the following: double low-E glazing, insulation, shading devices, daylight enhancment, night purge ventilation, LED light, and a high SEER hvac system to enhance the building performance and achieve Net-Zero energy. The results from eQUEST show a reduction of 68% from the total energy consumption of the building. Thus, 263 PV panels were implemented to generate the required energy for the building to achieve Net-Zero energy. Moreover, due to the fact that schools in Makkah have the same prototype, the Ministry of Education there can use this research as a case study to be applied to other schools in the area. The Net-Zero Energy for hot-arid climates would be an ideal concept to support the 2030 Vision of KSA, a nationwide initiative to make the country more sustainable.
    • Energy Conservation Techniques in Mid-Rise Residential Buildings that Contribute to Mitigate Urban Heat Island in Makkah, Kingdom of Saudi Arabia

      Alamri, Uthman Abdullah (The University of Arizona., 2018)
      The environmental consequences of nonrenewable energy production are present in Makkah, Kingdom of Saudi Arabia (KSA). Saudi energy production depends on fossil fuel combustion, which combined with energy production processes, results in the production of anthropogenic heat and greenhouse gas emissions. Greenhouse gases raise the concentration of these gases in the atmospheric boundary layer and contribute to the creation of an inversion layer (Sahashi, Hieda, and Yamashita 531-535). This leads to changing climatological parameters and the formation of urban heat islands. The urban heat island phenomena affects the environment around buildings. Rising temperatures are accompanied by extreme heat in the hot, arid, desert weather experienced during the day in Makkah, KSA. The urban heat island effect disturbs buildings’ indoor human thermal comfort. As a result, the building sector in Saudi Arabia accounts for 78% of the energy consumption and cooling load count for 70% of the total (BUILDINGS | Saudi Energy Efficiency Center 2018). Cooling systems produce heat waste, which counts as a source of anthropogenic heat, one of the principles of urban heat island formation that results in a high demand for energy production and anthropogenic heat again. This research aims to mitigate urban heat island formation by focusing on anthropogenic heat reduction from the building itself and power plants (energy consumption and energy production) by applying two packages of energy conservation strategies - Passive and Active - on a case study building in design phase. eQUEST energy modeling software was used to calculate the building’s annual consumption as well as energy saving from the case study after implementing energy conservation strategies. The strategies implemented in this study reduced the energy consumption from 1,119,600 kWh to 535,000 kWh. This accounts for a 53 % reduction of energy consumption, which in turn prevents the release of 730 metric tons of CO2. In summary, the building has a crucial impact on the local environment, and a well-designed building can enhance building energy performance, maintain energy production sources, and prevents climatological changes that happen due to anthropogenic heat production and energy consumption.
    • Reducing Energy Consumption of Residences and Evaluating On Site Outdoor Human Thermal Comfort in a Historic District in a Hot-Arid Climate through Strategic Implementation of Tree Canopies: A Case Study in the Armory Park Neighborhood

      Hornby, Rachelle LaRae (The University of Arizona., 2018)
      Historical buildings in their physical architecture, with their grand historic walls are a celebration of time, a story of the past. Beyond their architectural style they reflect the past and hold within them community, memories, and an era of the past that many community members hold dear to their hearts. Generations later stories are told, and if we are lucky, the buildings are still standing, repurposed or rehabilitated, to continue to hold not only history but a continued place to continue to hold future history along with it. Their history is not necessarily woven into the years of the walls themselves, but the memories they hold within them. With global warming and the current energy crisis it is important to prioritize energy efficiency measures to ensure a future availability of resources worldwide. Many energy efficient strategies, since not all are new, are often being implemented in buildings constructed in the past. The innovation on solutions for solving human safety and even human comfort are rooted in the very meaning of architecture from the beginning. It is then of main concern that, nowadays, these clear connection between architecture and environmental strategies are disconnected. Technological innovation has ended up challenging the relationship between environmentalist and historical preservationist. It is perceived that these professionals work in contrasting ends of the architectural fields, when, as it will be demonstrated, historical building in one hand bring simplified understanding of how accurately react to local environments, and on the other hand, state of the art environmental technology can preserve the buildings in better and long-lasting conditions. It is commonly seen that these fundamental approaches to applied knowledge are not collaborating and often it seems that they negate one another. Specifically addressing the neglected areas of deep analysis in the integration of new technologies to historic building, this document states how the field faces barriers for its implementation. Energy efficient strategies currently have the potential to threaten the historic integrity of a building, threatening its removal from the National Register of Historic Places. Developing strategies that compliment both disciplines is a necessity to ensure the protection of our heritage and protect the future of our built environment. Environmental and a historical preservation principles are applied to this research. The Goal is to create a methodology for bringing together the two disciplines to complement one another. This, in turn, has the potential to protect historical architecture and the future of the built environment simultaneously. This research concentrates on a residential home that is a contributing property in the Armory Park Historical District located in Tucson, AZ, which, due to the local environmental condition, faces extreme heat and aridity. The energy efficiency of this house is currently poor due, partially, to the absence of shading neither from architectural features nor from surrounding tree canopy or other vegetation, the latter being a strategy encouraged by historical preservationist. Therefore, this absence exposes the home to the harsh climatic conditions reducing its energy efficiency. A level III energy audit was performed on the home followed by a deep analysis using eQUEST software. Research was conducted to represent Mesquite trees, a successfully grown tree in the region, to create a simulation in eQUEST and study the effects of planting this species around a home and their effects on energy efficiency. It is found that the strategic placement of trees around this historical residence does not allow for solar radiation to affect the conditions of the context and the home itself. This research implemented eight different iterations of tree placements around the home. The iterations varied from one tree to six trees resulting in energy savings ranging from 9.53% to 10.90%. Water consumption to support a mesquite tree during the first four years to establish them was also analyzed. These trees would require 518 gallons of water per year, totaling 2072 gallons over a four-year period. This was then converted into its energy use equivalent in Kwh equating to 777 Kwh per year, or 3108 Kwh total for all four years per tree. Surface temperatures surrounding the home were also taken of the base case and an adjacent home to determine the differences between similar surfaces shaded by tree canopy and one lacking shading, these results reflected in a temperature differential of 30°F. In summary, research through data collection of surface temperatures, climate station analysis, energy audits, and energy simulation software was used to analyze current and simulated conditions. The results demonstrated the benefit of the implementation of strategically placed trees. To support future research, climate stations were implemented to collect data in neighboring homes microclimates, one containing vegetation and shade trees, and the other lacking, for a period of one day. Although this comparative study provided a glimpse at the varied microclimate from one home to the other and how this could affect the structures they surround, this data was not enough to support the differences in climate throughout a calendar year. This one-day pilot must inspire future effort to collect and analyze seasonal, annual and multiyear data for establishing reliable trends and patterns that lead to cost-effective and long-lasting strategies. Long term observations will also optimize the solutions and avoid unnecessary additions to the building that unfairly threaten its Historical Preservation value.
    • Screening In or Out Applicants with Disabilities: Interpreting Signals during the Job Application Process

      Duncan, Kaylin Louise (The University of Arizona., 2018)
      During the job search, applicants receive many signals about a company through recruitment procedures and materials. These signals can alter applicants’ perceptions and behaviors in the employment process. Of particular concern, applicants with disabilities often encounter signals encouraging or discouraging their participation in the application process. I conducted a study examining how people with and without disabilities interpret the signal, the Voluntary Self-Identification of Disability (VSD) form, during the job application process. Moreover, I examined whether perceived stigma of disabilities listed on the form affects individuals’ likelihood to disclose a disability on the VSD form and apply for a job position requiring this form. Results indicate that respondents infer positive, negative, neutral, and conflicting interpretations of the VSD form during the job application process. Respondents noted the following themes in their interpretations of the VSD form: discrimination, privacy violation, assumption of dishonesty, legal reasons, person/job fit, equality, accommodations, and format. Individuals’ perceived stigma of disabilities on the VSD form was not associated with their likelihood to apply for a position. However, perceived stigma of mental health disabilities, but not physical, was negatively associated with individuals’ disclosure of a disability on the VSD form. With more insight on organizational signals, employers and policymakers can better design and develop recruitment materials to improve the application process for people with disabilities.
    • Dating Intentions and Sexual Self-Presentations: A Content Analysis of Users’ Profile Pictures on Online Dating Services

      Yan, Kun (The University of Arizona., 2018)
      Online sexual self-presentation is a strategy in which individuals utilize sexuality to promote themselves in the online environment. Based on the self-presentation theory and self-sexualization, I postulate that the behavior of sexual self-presentation will be demonstrated visually in the profile photos that online daters post. This study systematically investigated a total of 250 online daters’ sexual self-presentations on two dating services Wild and Plenty of Fish. In particular, seven sexualization-relevant cues (i.e., sexualizing eyes, clothing, body exposure, selfies, body focus, self touch, and other touch) were examined. Further, this study explored how online daters’ sexual self-presentations differ according to daters’ relational intentions, gender, age, and race. Results indicate that after removing “cannot tell” codes, one-third (33.2%, n = 78) of the profile photos (n = 235) displayed at least one explicit sexualized cue—revealing clothing and body exposure; half (49.6%, n = 124) of the profile pictures (n = 250) presented sexualized eyes. Additionally, 95.2% (n = 220) of the dating profile photos (n = 231) suggested potential body objectification (i.e., either utilizing selfies or partial/full body shots). The study also found that daters’ relational intentions were not associated with sexual self-presentation. Nevertheless, statistically significant gender differences existed in the world of online dating, with female daters utilizing more revealing clothing, body exposure, sexualizing eyes, and selfies in their profile photos than male counterparts.
    • Writing by Heart. Victims of the Colombian Armed Conflict Write their Testimonies

      Bungard, Claudia (The University of Arizona., 2018)
      The half-century Colombian armed conflict has left an enormous human impact. Statistics say that between 1956 and 2016 about seven million people have been victims of crimes perpetrated by guerrilla groups, paramilitaries, and the national army. For decades, most of the victims have maintained a complete silence about their tragedies. However, in recent years, with the guidance of journalists and social workers, some victims have started to write their own memories of the war. Between 2006 and 2010, as a way to collect testimonies and to give a “voice to the voiceless,” the local government of the city of Medellin, Colombia, supported a series of writing workshops in which victims wrote their own tragedies. In part, this thesis seeks to explore this new way to produce testimonies in Colombia and to show the impact of this grassroots memory project on participants. It also refers to its potential effects and legacy, in order to make recommendations for future such projects in times of transitional justice in Colombia.
    • Fiber Bundle Enodoscope

      Liao, Weichen (The University of Arizona., 2018)
      Fiber bundle has those great properties from optical fiber such as its flexibility and small size but is used for imaging. The goal in this thesis is to study the method to improve the optical performance such as resolution and field of view etc. in a fiber bundle micro-endoscope. The approaches are physically reshaped the tip of fiber bundle and design a prototype objective on the tip.
    • Informational and Energetic Masking Effects on Speech-Evoked Cortical Auditory Potentials

      Carter, Jared (The University of Arizona., 2018)
      Three experiments were undertaken to evaluate the effect of informational and energetic masking on obligatory and cognitive auditory evoked potentials, as well as perceptual responses, to speech and non-speech tokens. Perception of speech in noise is one of the more challenging tasks in which listeners engage. Understanding how the brain processes speech in noise helps clinicians develop therapies and outcome measures to assist individuals who struggle understanding speech in noise. The experiments were carried out in 15 young adult listeners with normal hearing. In Experiment I, the CAEP onset and acoustic change complex responses were obtained in response to vowel-consonant-vowel and tone-change tokens in quiet, and in three masker conditions, speech-shaped noise, 8-talker babble and 2-talker babble. In Experiment II, the same participants completed a VCV identification task in quiet, and with the three maskers used in Experiment I. In Experiment III the P300 was obtained while listeners were asked to identify tokens when presented in quiet and in the three masking conditions used previously. Experiment I results demonstrated that the introduction of maskers reduced the amplitude of the CAEP onset and ACC responses, for both VCV and tone-change tokens, and that the 2-talker babble masker had a greater effect on the responses to VCV tokens than to tone-change (non-speech) tokens. These effects were specific to the P2 component of the cortical onset response. The results of Experiment II revealed that the identification of only certain VCV-tokens were affected by the introduction of masking, and there was no differential effect of energetic vs. informational masking. In Experiment III, only the 2-talker babble reduced the P300 response amplitudes, indicating an effect of informational masking on the electrophysiologic response that was not seen in behavioral task of Experiment II. The differential effects of informational masking on auditory evoked potentials may be related to its acoustic parameters. The informational masker used in this study (2-talker babble) had a 5 Hz amplitude modulation that may evoke a phase-locked response, diminishing the neural complement that would otherwise respond to the stimulus. Differences in calibration of modulated vs. unmodulated maskers may also contribute to the effects seen. In addition, the spectral-temporal characteristics of the masker relative to the stimulus (speech or non-speech) can play a role. This study provides new knowledge about how the brain responds in a challenging listening situation when there is informational masking. The findings can contribute to developing clinical methods for diagnosis and/or prognosis of speech-in-noise problems that often drives people to seek hearing health care.
    • Software Implementation of a Combined Fluorescence and Swept Source Optical Coherence Tomography Imaging System

      Sassu, Matthew George (The University of Arizona., 2018)
      This paper serves as a detailed overview of the software developed for the Falloposcope endoscope being developed by the Jennifer Barton Optics Tissue Laboratory. The Falloposcope is designed for a screening procedure for early detection of ovarian cancer in the fallopian tubes. The software controls a charge-coupled device (CCD) camera to perform reflectance and fluorescence imaging, which serves to navigate the endoscope to the fallopian tubes and surveil suspicious tissue regions. It also controls a swept source optical coherence tomography (SS-OCT) imaging system to provide high resolution, cross-sectional tomographic images of these tissue regions. CCD imaging is performed using a Princeton Instruments Pixis 1024B Digital CCD camera system. OCT imaging is performed using a Santec HSL-2100 swept source infrared laser and BPD-200-ST photodetector, as well as an AlazarTech ATS-9462 data acquisition board. Data from these instruments is displayed on a graphic user interface written in C++/CLI. This paper details how each of these imaging systems functions, from hardware control through data processing and visualization, as well as how more challenging programming tasks were completed. The core functionality of each system is complete, but there remain some parameters of the OCT data display which remain to be finalized. The available options, as well as the standard practices within the medical industry around OCT imaging, are discussed.
    • Exploration of Sensor Systems for Increasing the Accuracy of Photovoltaic Modeling Application to the TEP/AZRISE Solar Test Yard

      Dzurick, Matthew (The University of Arizona., 2018)
      The TEP/AzRISE (Tucson Electric Power/Arizona Research Institute for Solar Energy) solar test yard is a test-bed for multiple installations of various grid-tied photovoltaic (PV) modules and associated data collection systems that is located on the TEP campus in Tucson, AZ. Modules installed at the test yard are instrumented and data related to module/string power production and local field conditions are continuously collected. Additional data acquisition has been implemented via SOFIE (Smart Solar Field) which is a movable unit that has been recently serving as a primary data acquisition system at the TEP/AzRISE solar test yard. SOFIE has the capability to measure DNI (Direct Normal Irradiance), DHI (Diffuse Horizontal Irradiance), GHI (Global Horizontal Irradiance), POA (Plane of Array) Irradiance, wind velocity, wind direction, ambient temperature, and back of panel temperature. The measurement capabilities of SOFIE greatly enhance the sheer volume of data that is collected at the TEP/AzRISE solar test yard and serves to complement and confirm data acquisition systems that are already in place. In this thesis, experimental and modeling efforts to determine the impact of field-condition data fidelity and accelerated-aging test data availability on the accuracy of predictive PV power generation models will be examined. As such, a number of topics will be discussed and explored. These include the deployment of both SOFIE and an additional solar panel string at the test yard, the update of the test yard data acquisition system which now automatically transports data to the University of Arizona UAPV servers, thus greatly improving data accessibility, and modeling methods for PV power prediction. Additionally, the impact of test yard and laboratory data on the accuracy of PV power forecasting models will be examined and discussed. Finally, overarching conclusions and work remaining for future investigation will be presented.
    • Fractional Control of Multivehicle Systems and Relative Orbits

      Yaylali, David (The University of Arizona., 2018)
      Cooperative control protocols can be formulated for systems comprising multiple independent agents which can share information. In this work I will consider the cooperative control problem for multi-agent systems whose agents obey second-order Newtonian dynamics. Specifically, I will explore consensus and cooperative control laws for arrangements of both free point-mass bodies and point-mass spacecraft in orbit about a celestial body. In the latter case, the linearized equations of motion for two or more bodies in orbit will be used, allowing us to frame cooperative control laws in the standard formalism of algebraic graph theory. One of the primary novelties explored in this work is the usage of non-integer order integral and derivative operators in the feedback controllers for cooperative multiagent systems. These fractional operators provide additional degrees of freedom in controller design, and therefore afford more freedom in shaping the controlled system’s trajectories. Among the main results presented in this work, we prove the stability of certain fractional consensus controllers and show that these controllers can outperform standard integer-order controllers in terms of some important performance measures.
    • Acoustic Imaging of Geosynchronous Satellites via a Newly Upgraded Hyper-Temporal Imaging Instrument

      Morris, Marita D. (The University of Arizona., 2018)
      Presented here are investigations into acoustic imaging techniques designed to identify geosynchronous (GEO) satellites by their polarization signatures. In order to conduct these observations, a hyper-temporal imaging (HTI) instrument has been developed. This new instrument has been designed to operate on the 61” Kuiper telescope, located on Mount Bigelow, Arizona. At the core of HTI is a polarizing beam splitter and two identical cameras which record s and p linear polarized channels simultaneously. These two channels are then used to calculate degree of linear polarization of the signal over time. The latest upgraded cameras are each Andor Zyla 4.2+sCMOS. These cameras are capable of recording data at speeds greater than 1000fps with a Field of View of 5 arcminutes. Typical site conditions at the telescope give an estimated 1 arcsecond of seeing (on good nights), thus the optical aberrations in HTI have been designed to be far less than this limit. Observations with the HTI instrument were conducted over 10 nights and data were collected on 22 different GEO satellites plus several stars for comparison. Here three of these target satellites are analyzed in detail for their unique signatures. StarOne/Brasilsat B4 (HS-376W bus) is a known spin-stabilized satellite. It showed clear peaks in the signal of: 0.53Hz, 1.06Hz, 1.59Hz, 2.1Hz, 2.65Hz, 3.18Hz, and 3.71Hz. Ciel-2 (Spacebus-4000C4 bus) is one of the larger of these GEO satellites and showed a signal which may be consistent with a satellite maneuver. This signal showed peaks in the power spectrum of DOLP at: 0.028, 0.043, 0.08, 0.26Hz. The third satellite, DirecTV-15 (Eurostar-3000 bus) also contained a signal which appears to be a satellite maneuver taking place. Peak frequencies of 0.069Hz and ~0.05Hz were observed in this signal.
    • A Predictive Model for the Production Rates of a Bioregenerative Life Support System

      Gellenbeck, Sean Christian (The University of Arizona., 2018)
      Future long-term human space flight will require systems that are reliable, sustainable, and can continue to function for the entire length of the mission. Included in these possibilities are a relatively short two-year expedition to Mars as well as the indefinite colonization of another celestial body. Life support presents a significant challenge to this concept as many of the systems currently in use would require bringing a prohibitively heavy and bulky amount of supplies and consumables. An additional challenge is what to do with all the refuse from humans and other systems within the habitat. An innovative solution that addresses both of these problems is the use of bioregenerative life support (BLS). This type of life support utilizes the evolutionarily refined abilities of biological organisms to produce oxygen and sequester carbon dioxide through photosynthesis, purify water through transpiration, and produce edible biomass and calories for human consumption. In addition to being reliable, these systems operate at ambient conditions which reduces risk, and also provide psychological benefits to the crew. A successful BLS system will likely include many subsystems of which a higher plants production chamber will be one. The inclusion of biology as part of a life support system introduces complexity and mathematical models that can accurately predict the production rates of these systems is necessary. One such model that describes the production of a higher plants growth system is the Modified Energy Cascade Model (MEC) which was developed by James Cavazzoni in the early 2000’s. Around this model, a wrapper was developed to allow a user or system designer to input parameters for a hypothetical design and receive graphics depicting the production rates of said system over the entire course of the proposed mission for two different harvest strategies. This allows the user to accurately predict the production of any design and optimize to find the solution that best fits the needs of the mission. Four different BLS system example analogues were analyzed to show this utility and to allow for the further discussion of the design process surrounding such a system. This tool could also be modified to allow the design to identify deficiencies in the astronauts’ diets and show the effect of variable environmental conditions. In its current form, this tool would have the most potential benefit during the system and concept of operations (ConOps) design phases of a life support system for a long duration human space flight mission.
    • Exploration of Student Perceptions of Team-Based Learning in a Collaborative Space

      Nguyen, Elizabeth (The University of Arizona., 2018)
      This study investigates student perceptions of team-based learning (TBL) in a collaborative learning space using a qualitative, single case study of an undergraduate, entrepreneurial leadership course taught in the spring 2018 using a flipped delivery model. There were 11 participants that were interviewed three times throughout a 16-week semester: once at the beginning of the semester, once mid-semester, and a final time at the end of the semester. The participants were also observed throughout the entirety of the entrepreneurial leadership course. The findings revealed that (i) the primary focus of the students was on the team experience, (ii) students in a leadership role wanted additional support as the semester progresses, (iii) the collaborative design of the classroom space was not fully utilized by the students, and (iv) there was a positive perception of TBL. Recommendations for practice and research are provided.