• A Comparison of Electromagnetic Physical Scale and Numerical Modeling for Geophysical Exploration

      Burkart, Riley (The University of Arizona., 2018)
      Numerical modeling has, in the twenty-first century, become the dominant form of modeling for electromagnetic exploration geophysics, but few studies have been undertaken that compare numerical models with physical scale models to determine the constraints on numerical algorithms. In this thesis, a physical scale model system was constructed and twenty-six profiles run to analyze the strengths and limitations of four algorithms in PetRos EiKon's EMIGMA V8.6 modeling software: Free Space EikPlate (FS Plate), VH Plate, Inductive Localized Non-Linear (ILN), and EMSPHERE. A low-power vertical-array system with a ten-turn square transmitter loop and receiver coils in the Bx, By, and Bz directions with ten turns, ten turns, and two turns, respectively, was designed and constructed for this thesis. Profiles were taken in either a lab setting, which provided more space, or a tank setting, which allowed for lower noise and modeling of a conductive host. A total of twenty-six profiles taken with ten targets are presented here together with their geometric configurations. Through comparison of the measured and the simulated data, the following conclusions are made: (1) The VH Plate and ILN algorithms produce less accurate simulations for small targets; this may be redressed by increasing the scale of the targets. (2) Every algorithm designed to account for galvanic responses, when otherwise operating within its constraints, does so effectively and corroborates the measured data. (3) FS Plate simulations reasonably approximate the measured responses of long sheet targets when the sheet center is distal to the receiver by more than one third the sheet length, but do not approximate the measured data as well when the center of the target is proximal to the receiver. (4) EMSPHERE, which is only supported for dipole sources, does not approximate a target with a loop source well when the target is directly beneath the transmitter, but it does approximate it well when the target is displaced from the transmitter; a sphere may be approximated for the ILN algorithm by a cube that fits flush within the sphere. (5) FS Plate peak responses tend to be smaller than the measured responses by a factor of two, but the side skirts match well; FS plate also appears to diverge from the Kramers-Kronig relations for induction numbers smaller than 2e-4. (6) VH Plate peak responses tend to be larger than the measured responses by a factor of roughly two, and the side skirts do not match well. (7) ILN breaks down for high conductivity contrasts, such as a graphite cube in air; this issue may be avoided by using a more resistive host for the model so long as inductive effects still dominate, which may be determined using LN.
    • A Method for Analyzing Microclimate Effect of Shaded Transitional Spaces on Outdoor Human Thermal Comfort and Building Performance in a Hot Arid Region

      Horn, Patricia (The University of Arizona., 2018)
      Spaces are usually classified as either being indoors – frequently private or public outdoor spaces. Transitional spaces are an important aspect to the built environment as they have great potential to modify the environmental conditions of both indoor and outdoor spaces. They are the connecting space between the outdoor and indoors, between the natural climate and controlled climate. They can aid to building efficiency and to outdoor human thermal comfort. Transitional spaces in a hot arid region are crucial to maintaining the comfort of a user while being outside. The purpose of this investigation is to prove that shaded outdoor transitional spaces can lead to outdoor human thermal comfort and building performance. The problem being addressed is the lack of attention on shaded transitional spaces in a hot arid climate. Being located in such a harsh climatic environment it is important to look into the relationship between the building and its outdoor spaces as well as users. They are used to create a comfortable microclimate while transitioning into the building. A 9 step method will be proposed to defend the idea that shaded transitional spaces can lead to outdoor human thermal comfort and building efficiency. Methods being used are eQUEST Simulations, micro-climate data collection, and calculating outdoor human thermal comfort. The results confirmed the notion that shaded transitional spaces can lead to outdoor human thermal comfort and building performance. The comfort of the user was defined and the performance of the building was established through energy modeling simulations.
    • A Nanometric View into Strengthening Mechanisms of Iron Incorporation in Graphene-Based Nanocomposites

      Rand, Matthew (The University of Arizona., 2018)
      Recent advances in the ability to synthesize metal-ion coagulated graphene oxide (GO) colloidal dispersions have provided new avenues for fabrication of GO based thin films and membranes. Additionally, new fabrication techniques have recently emerged that enable the ability to intercalate and reduce metal halides in bulk graphite crystals, leading to metal-based graphite intercalated compounds (GICs). To this end, a fundamental study on the interplay between composition, atomic-scale structure and mechanical properties of metal-GO as well as metal-GIC composite materials was carried out employing molecular dynamics (MD) simulations. Specifically, the transition metal iron (Fe) was considered in this study; MD investigations reveal that Fe ions act as strong cross-linkers between individual GO sheets, increasing elastic modulus as well as tensile strength of the Fe-GO composite. Investigations of Fe intercalated GIC (Fe-GIC) showed interesting trends in its mechanical properties due to bond formation between the intercalated Fe atoms and the ‘sandwiching’ graphene sheets. In particular, with increasing iron concentration, there is strengthening in the out-of-plane direction, while reduction in the in-plane direction of the Fe-GIC lattice. While the Fe-C bonding ensures out-of-plane strengthening, it is equally detrimental to the strength of the in-plane C-C bonds within the graphene sheets. Valuable lessons learned from this work provide important insights into the design and development of GO and GIC composites for targeted mechanical and chemical applications.
    • 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.
    • A Study of Adversarial Attacks Against an LSTM Language Model and the Impact of Normalization in SNN

      Liang, Zhengzhong (The University of Arizona., 2018)
      Artificial Neural Networks (ANNs) have been used to many application-driven fields and have been shown to be quite successful, however, some aspects of ANNs are not well understood. One such area is learning an ANN in the presence of an adversary.In such a context, it is assumed that the attacker can manipulate the training (also referred to causative attack or poison) or testing data (also referred to exploratory attack) to disrupt its normal functionality. In turn, the defender aims at reducing the impact of such attacks as much as possible. The first part of this thesis focuses on causative attacks against an Long Short-Term Memory (LSTM) neural network in a language model. In causative attacks, it is assumed that the attacker can only change the training text in the language model. We study the behavior of the LSTM language model under different causative attacks and propose several simple measures that can reduce the impact of the attacks. Our results show that the poisoning ratio, the poisoning position and the generation of poisoned text can all influence the performance the LSTM language model. Furthermore, we show that proper use of dropout and gradient clipping can reduce the impact of poisoning the training data to some extent. We also contribute to understanding how to globally learn a Spiking Neural Network (SNN). SNNs are a type of ANN; however SNNs are much more biologically realistic than other ANNs. SNNs have not been widely adopted because of several critical issues of SNNs that are not well studied. One such effect is the training of SNNs and the encoding/decoding of signals in SNNs. In the second part of this thesis, we build an SNN based image classifier to study the encoding/decoding of signals and compare several learning rules for training an SNN. Results reveal that (i) classical STDP learning windows generally obtain the best performance using different decoding schemes; (ii) first-spike decoding has worse accuracy than count decoding classifier does when no normalization rules are applied, although first-spike decoding classifier consumes much less time than count decoding classifier; (iii) the performance of first-spike decoding classifier can be largely enhanced with proper use of normalization rules.
    • A Systematic Review of Recruitment and Retention Strategies Used in Dietary Randomized Controlled Interventions in Cancer Survivors

      Lavelle, Sarah Arline (The University of Arizona., 2018)
      Interpretation of results of dietary intervention trials in cancer survivors may be limited by insufficient recruitment or retention of study participants. This systematic review describes recruitment strategies, accrual of participants, and attrition (withdrawal) rates for dietary interventions conducted in breast, prostate, and colorectal cancer survivors. PubMed, CINAHL, Cochrane Central Register of Controlled Trials, Embase, PsychINFO, and Web of Science databases were searched. Eligible studies included national and international dietary randomized controlled trials (RCTs), with at least 12 weeks of intervention and 6 months of follow-up. Trials were required to include a CONSORT (CONsolidated Standards of Reporting Trials) diagram. Twenty cohorts were included: breast cancer (BC) survivors (n=11), prostate cancer (PC) (n=3), colorectal cancer (CRC) (n=1), and combined (n=5). Primary recruitment methods included health care providers (n=13) or cancer registries (n=9). Of studies that set a priori sample sizes, 12 met accrual targets and five did not. Attrition rates averaged 18.6% at 6 months, 16.3% at 12-13 months, and 20.3% at 2 years. Among completed studies (n=18), seven trials met a priori retention targets, three trials did not, one assessed feasibility, and seven trials did not provide a clearly defined retention goal. There were few trials in PC and CRC survivors. Missing CONSORT diagrams reduced the eligible studies. The majority of studies met recruitment goals (n=12). Overall, attrition rates averaged approximately 17.4%. Improved understanding of effective recruitment and retention strategies requires more diligent reporting. Qualitative research may allow for more systematic and detailed evaluation of challenges that contribute to insufficient recruitment and retention of cancer survivors in dietary intervention trials. Registration can be found at PROSPERO ref: CRD42018070396.
    • A Visual Analysis of Local Food Taste Regime in Conventional and Unconventional Marketplaces

      Thorp, Tyler (The University of Arizona., 2018)
      The Local Food Movement (LFM) is composed of a complex network of actors including producers (e.g., farmers, ranchers, processors), purveyors (e.g., farmers’ market vendors, retailers, restaurateurs), organizers (e.g., farmers’ market operators, food bank administrators) and narrators (e.g., local food journalists). Limited governance within local food systems (LFSs) and a lack of consensus on the definition of ‘local food’ provide such actors with notable latitude in how they frame the meaning of ‘local’ in the products they produce, market, and sell. The expansion of food products that are framed as being local within conventional retail sites may be further convoluting the meaning and representation of local food across the disparate market sites that operate within a single LFS (e.g. community gardens, farmers’ markets, festivals, grocery stores, roadside stands, you-picks). Thus, consumers are left to sort through a variety of elements (e.g., activist, aesthetic, community, cultural, ecological, economic, health and wellness) that converge and compete to shape their understanding of local food and guide their consumption decisions. Here, I use a structured photo analysis design to explore the elements that influence the visual representation of local food within five farmers’ markets and five grocery stores within the Southern Arizona Local Food System (SALFS). The theoretical principles of institutional logics guide my identification and analysis of the beliefs, motives, practices and values that guide the framing practices and strategies of local food actors within various retail settings. Commodification, the act of turning something with intrinsic value into a exchangeable good, is used to reveal how the various elements that underpin the LFM are (or are not) being leveraged to support the representation of local food products across different retail settings. The theoretical principles of taste regimes, the concept that social groups with high levels of cultural capital have the greatest influence over the meaning and legitimacy of products within an aesthetically oriented culture of consumption, is used to analyze the similarities and differences between the representations of local food within and across the 10 retail locations. The findings illustrate how local food framing practices and strategies across conventional and unconventional retail sites foster a local food taste regime that is mostly inconsistent with the fundamental principles and values of the LFM. Recommendations for local food practitioners and further research are provided.
    • Abe Lincoln in Illinois: from historical figure to state character

      Cook, Harlin Maurice, 1925- (The University of Arizona., 1952)
    • ABERRATION FIELD PROPERTIES OF SIMPLE NON-AXIALLY SYMMETRIC OPTICAL SYSTEMS.

      Jewell, Tatiana Emelianovna. (The University of Arizona., 1984)
    • ABILITY GROUPING IN A COLLEGE CHEMISTRY LABORATORY COURSE.

      Chambers, Rebecca Anne. (The University of Arizona., 1985)
    • The ability of a group of prospective teachers in speech skills

      Cook, Robert Verne, 1923- (The University of Arizona., 1951)
    • The ability of the dog to utilize vitamin A from vegetable and from animal sources

      Bradfield, Dorothy Marie, 1905- (The University of Arizona., 1937)
    • An Abled Nation: Disabled Athletes in Japan and How Their Bodies are Governed

      Supplitt, Timothy (The University of Arizona., 2017)
      This thesis analyzes the ways in which the Japanese state uses the disabled body and disability athletics as a tool of governance and how that affects the incorporation of disabled people into Japanese society. Throughout Japan's history the disability identity has been a subject of negotiation between social actors including the government, general public, those with disabilities, and powerful international collectives. After World War II, disabled former soldiers were celebrated for their national sacrifice while other disabled bodies were displaced. In later decades, disability athletics became a space where the symbol of the ideal disabled body has been promoted for public consumption. On the stage of athletics, various actors have shaped and influenced each other by advocating different visions of the disabled body in Japanese society. Disabled athletes negotiate depictions of disability as idealized (the 'super crip') or stigmatized (the 'pitiable disabled person'), and these depictions in turn create public expectations for what the disabled body should be but at times glosses over the struggles of many disabled people. The purpose of this thesis is to consider how notions of the disabled body are used to negotiate nationalism, modern ideas of care and social responsibility, and expectations to become a body of inspiration for the disabled community and the general public. The core question is: What are the implications of the disabled body being used as a tool on the stage of disability athletics for governance in modern day Japan? The thesis will provide a basis for deeper understanding about the relevance of disability athletics as both a form of governance and a site of identity formation for the disabled.
    • Abortion and the Media: An Analysis of Wichita

      Noll, Kimberlee Elizabeth (The University of Arizona., 1992)
    • Abortion Coverage: Are the Media Biased?

      Rittner, Marianne (The University of Arizona., 1990)
    • Abortion legislation: stringency, reform, or repeal?

      Nolan, Nellie Jean, 1947- (The University of Arizona., 1974)
    • Absolute calibration of spectrometer through the ultraviolet

      Kowalski, Brian Keith, 1961- (The University of Arizona., 1993)
      The beam-foil source can be developed as an absolute intensity secondary standard light source. A spectrometer and optical system are calibrated using a standard tungsten filament (blackbody) lamp whose intensity calibration is traceable to the National Bureau of Standards. Knowing the number of photons emitted by the lamp, we determine a wavelength dependent system efficiency. By careful comparison of the intensity of spectral lines emitted from the beam-foil source to an appropriate portion of the continuous spectrum emitted from the standard blackbody lamp, the beam-foil source is calibrated over the same region of the spectrum as is the standard lamp. Branching ratios are then used to extend this calibration into the vacuum ultraviolet.