• Modeling Orbital Motion in a Circular Conic Reference Frame

      May, Douglas H.; University of Arizona (American Institute of Aeronautics and Astronautics, 2022-12-29)
      Two-body orbital trajectories conform to conic sections. However, typically in the literature their motion is analyzed in a plane. Kepler modeled elliptic orbital motion in a plane, stated his second law, and derived the geometric position-time relationship as the uniform change in area with respect to time. Kepler’s equation has been applied extensively and proven to give time as a function of position for exact solutions to orbital problems. An identical equation has been derived without reliance on geometry alone by applying basic principle of classical mechanics and the calculus. When the elliptic orbit is analyzed as a section of a circular cone and represented in three dimensions, additional variables relate position and time. In a conical reference frame, the planar and conic representations merge. This paper combines the conic section knowledge and characteristics of the cone to introduce a third dimension to modeling orbital motion. Force and potential energy have indeterminate limits because potential energy approaches zero as the radius approaches infinity and the gravitational force approaches infinity as the radius vector approaches zero, a singularity. The conic frame includes the apex where the singularity of a radius of zero is an established point in the reference system.
    • Development and Flight Performance of the Autonomous Navigation Feature Catalog for OSIRIS-REx Asteroid Sample Collection

      Mario, Courtney; Miller, Curtis; Norman, Chris; Olds, Ryan; Palmer, Eric; Weirich, John; Lorenz, David A.; Barnouin, Olivier; Bos, Brent J.; Rizk, Bashar; et al. (American Institute of Aeronautics and Astronautics, 2022-12-29)
      The OSIRIS-REx spacecraft successfully collected a sample from the asteroid Bennu in October 2020, enabled by the vision navigation system Natural Feature Tracking (NFT). NFT autonomously provided state updates by matching features defined from Bennu shape model data to onboard camera images and allowed the spacecraft to touch down within 1 meter of the targeted location. This paper presents the development process and flight performance of the feature catalog used for navigation, including findings about terrain characteristics of robust features, validation methodologies despite limited test imagery, and trends between feature terrain content and final feature performance.
    • Adaptive Scale Factor Compensation for Missiles with Strapdown Seekers via Predictive Coding

      Gaudet, Brian; Drozd, Kris; Furfaro, Roberto; University of Arizona (American Institute of Aeronautics and Astronautics, 2022-12-29)
      In this work we present a method to adaptively compensate for scale factor errors in both rotational velocity and seeker angle measurements. The adaptation scheme estimates the scale factor errors using a predictive coding model implemented as a deep neural network with recurrent layer, and then uses these estimates to compensate for the error. During training, the model learns over a wide range of scale factor errors that ideally bound the expected errors that can occur during deployment, allowing the deployed model to quickly adapt in real time to the ground truth error. We demonstrate in a realistic six degrees-of-freedom simulation of an exoatmospheric intercept that our method effectively compensates for concurrent rotational velocity and seeker angle scale factor errors. The compensation method is general in that it is independent of a given guidance, navigation, and control system implementation. Although demonstrated using an exoatmospheric missile with strapdown seeker, the method is also applicable to endoatmospheric missiles with both gimbaled and strapdown seekers, as well as general purpose inertial measurement unit rate gyro compensation.
    • Integrated Guidance and Control for Lunar Landing using a Stabilized Seeker

      Gaudet, Brian; Furfaro, Roberto; University of Arizona (American Institute of Aeronautics and Astronautics, 2022-12-29)
      We develop an integrated guidance and control system that in conjunction with a stabilized seeker and landing site detection software can achieve precise and safe planetary landing. The seeker tracks the designated landing site by adjusting seeker elevation and azimuth angles to center the designated landing site in the sensor field of view. The seeker angles, closing speed, and range to the designated landing site are used to formulate a velocity field that is used by the guidance and control system to achieve a safe landing at the designated landing site. The guidance and control system maps this velocity field, attitude, and rotational velocity directly to a commanded thrust vector for the lander’s four engines. The guidance and control system is implemented as a policy optimized using reinforcement meta learning. We demonstrate that the guidance and control system is compatible with multiple diverts during the powered descent phase, and is robust to seeker lag, actuator lag and degradation, and center of mass variation induced by fuel consumption. We outline several concepts of operations, including an approach using a preplaced landing beacon.
    • Quadratic discriminant analysis by projection

      Wu, Ruiyang; Hao, Ning; Department of Mathematics, The University of Arizona (Elsevier BV, 2022-07)
      Discriminant analysis, including linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA), is a popular approach to classification problems. It is well known that LDA is suboptimal to analyze heteroscedastic data, for which QDA would be an ideal tool. However, QDA is less helpful when the number of features in a data set is moderate or high, and LDA and its variants often perform better due to their robustness against dimensionality. In this work, we introduce a new dimension reduction and classification method based on QDA. In particular, we define and estimate the optimal one-dimensional (1D) subspace for QDA, which is a novel hybrid approach to discriminant analysis. The new method can handle data heteroscedasticity with number of parameters equal to that of LDA. Therefore, it is more stable than the standard QDA and works well for data in moderate dimensions. We show an estimation consistency property of our method, and compare it with LDA, QDA, regularized discriminant analysis (RDA) and a few other competitors by simulated and real data examples.
    • Control, cost, and confidence: Perseverance and procrastination in the face of failure

      Deimen, Inga; Wirtz, Julia; University of Arizona, Eller College of Management, Department of Economics (Elsevier BV, 2022-07)
      We study effort provision and the development of the belief that effort matters over time: a student is uncertain whether she has control over success through her effort or whether success is determined by her innate ability, which she also does not know. In each period, what she can learn about her control and her ability depends on the level of effort she exerts. The student's optimal effort policy in this two-dimensional bandit problem takes the form of a linear belief cutoff rule and typically features repeated switching of the effort level. Moreover, we define perseverance and procrastination as indices for the student's behavior over time and analyze how they are affected by control, cost, and confidence. Finally, we relate our results to findings in educational psychology and discuss policies to foster perseverance and to lower procrastination.
    • Counteracting Dark Web Text-Based CAPTCHA with Generative Adversarial Learning for Proactive Cyber Threat Intelligence

      Zhang, Ning; Ebrahimi, Mohammadreza; Li, Weifeng; Chen, Hsinchun; University of Arizona (Association for Computing Machinery (ACM), 2022-06-30)
      Automated monitoring of dark web (DW) platforms on a large scale is the first step toward developing proactive Cyber Threat Intelligence (CTI). While there are efficient methods for collecting data from the surface web, large-scale dark web data collection is often hindered by anti-crawling measures. In particular, text-based CAPTCHA serves as the most prevalent and prohibiting type of these measures in the dark web. Text-based CAPTCHA identifies and blocks automated crawlers by forcing the user to enter a combination of hard-to-recognize alphanumeric characters. In the dark web, CAPTCHA images are meticulously designed with additional background noise and variable character length to prevent automated CAPTCHA breaking. Existing automated CAPTCHA breaking methods have difficulties in overcoming these dark web challenges. As such, solving dark web text-based CAPTCHA has been relying heavily on human involvement, which is labor-intensive and time-consuming. In this study, we propose a novel framework for automated breaking of dark web CAPTCHA to facilitate dark web data collection. This framework encompasses a novel generative method to recognize dark web text-based CAPTCHA with noisy background and variable character length. To eliminate the need for human involvement, the proposed framework utilizes Generative Adversarial Network (GAN) to counteract dark web background noise and leverages an enhanced character segmentation algorithm to handle CAPTCHA images with variable character length. Our proposed framework, DW-GAN, was systematically evaluated on multiple dark web CAPTCHA testbeds. DW-GAN significantly outperformed the state-of-the-art benchmark methods on all datasets, achieving over 94.4% success rate on a carefully collected real-world dark web dataset. We further conducted a case study on an emergent Dark Net Marketplace (DNM) to demonstrate that DW-GAN eliminated human involvement by automatically solving CAPTCHA challenges with no more than three attempts. Our research enables the CTI community to develop advanced, large-scale dark web monitoring. We make DW-GAN code available to the community as an open-source tool in GitHub.
    • Justice in emergency medicine

      Iserson, Kenneth V.; Department of Emergency Medicine, The University of Arizona (Elsevier BV, 2022-06)
    • Is the gender difference in competitive behavior history dependent?

      Rhee, Elaine; Noussair, Charles N.; University of Arizona, Department of Economics (Elsevier BV, 2022-06)
      This study tests whether men and women differ in their willingness to challenge a competitor in response to a prior transgression. A laboratory experiment is conducted, in which a player can choose to behave unfairly toward another. The other player may then challenge the first to a contest. We investigate the extent to which previous interactions can explain individual differences in tournament initiation decisions. The results show that men, but not women, tend to challenge a competitor more when the prior outcome is unfair and the unfairness occurred through the competitor's intentional choice. In contrast, unfair outcomes that occur by chance do not influence the decision to challenge others.
    • {Moco}n, (n = 0–8): A general formalism for describing the highly covalent molybdenum cofactor of sulfite oxidase and related Mo enzymes

      Enemark, John H.; Department of Chemistry and Biochemistry, The University of Arizona (Elsevier BV, 2022-06)
      Over 50 molybdenum enzymes in three distinct families (sulfite oxidase, xanthine oxidase, DMSO reductase) are known, and representative X-ray crystal structures are available for all families. Structural analogues that replicate the coordination about the Mo atom in the absence of surrounding protein have been synthesized and characterized. The properties of metal complexes of non-innocent dithiolene ligands and their oxidized counter parts, dithiones, are summarized. Pulsed electron paramagnetic resonance (EPR) spectroscopy of the 33S-labeled molybdenum domain of catalytically active bioengineered sulfite oxidase has clearly demonstrated delocalization of electron density from MoV to the dithiolene component of the molybdenum cofactor (Moco) of the enzyme. Moco is highly covalent and has three redox active components: the Mo atom; the dithiolene; and the pterin. In principle, Moco can have a total of eight redox states, making it one of the most redox rich cofactors in biology. The {Moco}n formalism, developed here, gives the total number of electrons (n) associated with a particular redox state of Moco. This flexible notation eliminates the need to assign a specific oxidation state to each of the three components of Moco and allows for internal redistribution of electrons among the components upon substrate binding, changes in the surrounding network of hydrogen bonds, conformational changes, and catalysis. An unexpected result is that sulfite oxidase (an oxotransferase) is predicted to utilize the {Moco}4–6 electron distributions during catalysis, whereas xanthine oxidase (a hydroxylase) is predicted to utilize the {Moco}6–8 electron distributions during catalysis.
    • ‘No Life Here:’ The Effects of Motion Picture Incentive on Below the Line Labor in Hollywood South

      Lukinbeal, Christopher; Sharp, Laura; University of Arizona (Springer, 2022-05-17)
      In 2002, Louisiana was one of the first states to begin a motion picture incentive (MPI) program to lure film and television production away from Los Angeles. Today, Louisiana, and especially its media capital, New Orleans, has been described as “Hollywood South,” a prominent North American film and television production center. This satellite production center is the outcome of a trend in local and national governments to use MPI programs to encourage the outsourcing of labor from Los Angeles since the mid-1990s. Using in-depth interviews with location managers in Louisiana, a review of policy documents, and an analysis of public discourse around the phenomenon in Louisiana, we examine the geography of Hollywood South, focusing on local labor and the consequences, efficacy, and ethics of its MPI program.
    • Estimation of direct-seeded guayule cover, crop coefficient, and yield using UAS-based multispectral and RGB data

      Elshikha, Diaa Eldin M.; Hunsaker, Douglas J.; Waller, Peter M.; Thorp, Kelly R.; Dierig, David; Wang, Guangyao; Cruz, Von Mark V.; Katterman, Matthew E.; Bronson, Kevin F.; Wall, Gerard W.; et al. (Elsevier BV, 2022-05)
      Guayule (Parthenium argentatum, A. Gray), a perennial desert shrub, produces high-quality natural rubber and is targeted as a domestic natural rubber source in the U.S. While commercialization efforts for guayule are on-going, crop management requires plant growth monitoring, irrigation requirement assessment, and final yield estimation. Such assistance for guayule management could be provided with remote sensing (RS) data. In this study, field and RS data, collected via drones, from a 2-year guayule irrigation experiment conducted at Maricopa, Arizona were evaluated. In-season field measurements included fractional canopy cover (fc), basal (Kcb) and single (Kc) crop coefficients, and final yields of dry biomass (DB), rubber (RY), and resin (ReY). The objectives of this paper were to compare vegetations indices from MS data (NDVI) and RGB data (triangular greenness index, TGI); and derive linear prediction models for estimating fc, Kcb, Kc, and yield as functions of the MS and RGB indices. The NDVI and TGI showed similar seasonal trends and were correlated at a coefficient of determination (r2) of 0.52 and a root mean square error (RMSE) of 0.11. The prediction of measured fc as a linear function of NDVI (r2 = 0.90) was better than by TGI (r2 = 0.50). In contrast to TGI, the measured fc was highly correlated with estimated fc based on RGB image evaluation (r2 = 0.96). Linear models of Kcb and Kc, developed over the two years of guayule growth, had similar r2 values vs NDVI (r2 = 0.46 and 0.41, respectively) and vs TGI (r2 = 0.48 and 0.40, respectively). Final DB, RY, and ReY were predicted by both NDVI (r2 = 0.75, 0.53, and 0.70, respectively) and TGI (r2 = 0.72, 0.48, and 0.65, respectively). The RS-based models enable estimation of irrigation requirements and yields in guayule production fields in the U.S.
    • Mean markets or kind commerce?

      Dufwenberg, Martin; Johansson-Stenman, Olof; Kirchler, Michael; Lindner, Florian; Schwaiger, Rene; Department of Economics, University of Arizona (Elsevier BV, 2022-05)
      Does market interaction influence morality? We study a particular angle of this classic question theoretically and experimentally. The novelty of our approach is to posit that people are motivated by reciprocity – an urge many argue affects humans. While many have suggested that market interactions make people more selfish, our reciprocity-based theory allows that market interaction on the contrary induces more prosociality. Our experiment provides a test of the empirical relevance of such an effect, in some highly stylized settings. The results are broadly (but not completely) supportive. They may shed light on the development of morality and prosocial behavior over time, with respect to episodes in history where the nature of commerce was transformed.
    • Scale-up of membrane distillation systems using bench-scale data

      Hardikar, Mukta; Marquez, Itzel; Phakdon, Tenzin; Sáez, A. Eduardo; Achilli, Andrea; Department of Chemical and Environmental Engineering, University of Arizona; Water and Energy Sustainable Technology (WEST) Center, University of Arizona (Elsevier BV, 2022-05)
      A procedure to design full-scale air gap membrane distillation (AGMD) processes is presented. A mathematical model was then developed for both direct contact membrane distillation (DCMD) and AGMD. The model is centered on solving local mass and energy balances using a finite difference approach. The full-scale model was calibrated by utilizing the membrane distillation coefficient (MDC) determined by DCMD bench-scale experiments, as the sole adjustable parameter. The MDC was then used to model the water production and energy efficiency of a spiral-wound AGMD full-scale element. The model yields accurate representation of full-scale AGMD elements using polytetrafluoroethylene (PTFE) and polyethylene (PE) membranes. Full-scale experimental results obtained over a wide range of feed flow rates (2 to 4.5 L/min), temperatures (40 to 80 °C), and salinities (0 to 200 g/L NaCl) confirmed that the developed procedure can be applied to model and design large-scale AGMD elements. Furthermore, the model guides the selection of specific temperature and flow conditions at a given salinity and element geometry to maximize water production and energy efficiency. This methodology is suitable for rapid evaluation of novel MD membranes performance in field AGMD applications.
    • A homemade device for simultaneous measurement of pulmonary ventilation and metabolic rate in neonatal rodents

      Boyd, Brennan; Hoyer-Kimura, Christina; Wollman, Lila; Fregosi, Ralph F.; Department of Physiology, The University of Arizona; Department of Neuroscience, The University of Arizona (Elsevier BV, 2022-05)
      Various in vitro neonatal rodent models have been developed to study the control of breathing, but translation of the information requires a behavioral assay, which has led to the widespread use of plethysmography to measure breathing in awake neonatal rodents. Best practice requires correcting changes in ventilation to the corresponding change in metabolic rate, which is the main driver of pulmonary ventilation. Obtaining measures of both simultaneously is ideal, though technically difficult. Here we describe a simple, inexpensive home-made dual chamber approach for simultaneous measurement of pulmonary ventilation and metabolic rate. We found that the dual chamber provides values for pulmonary ventilation and metabolic rate that compare favorably with existing approaches.
    • Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

      Rieke, Elizabeth L.; Cappellazzi, Shannon B.; Cope, Michael; Liptzin, Daniel; Mac Bean, G.; Greub, Kelsey L.H.; Norris, Charlotte E.; Tracy, Paul W.; Aberle, Ezra; Ashworth, Amanda; et al. (Elsevier BV, 2022-05)
      Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity.
    • Eco‐evolutionary feedbacks among pollinators, herbivores, and their plant resources

      McPeek, Sarah J.; Bronstein, Judith L.; McPeek, Mark A.; Department of Ecology & Evolutionary Biology, University of Arizona (Wiley, 2022-04-28)
      Eco-evolutionary feedbacks among multiple species occur when one species affects another species’ evolution via its effects on the abundance and traits of a shared partner species. What happens if those two species enact opposing effects on their shared partner's population growth? Furthermore, what if those two kinds of interactions involve separate traits? For example, many plants produce distinct suites of traits that attract pollinators (mutualists) and deter herbivores (antagonists). Here, we develop a model to explore how pollinators and herbivores may influence each other's interactions with a shared plant species via evolutionary effects on the plant's nectar and toxin traits. The model results predict that herbivores indirectly select for the evolution of increased nectar production by suppressing plant population growth. The model also predicts that pollinators indirectly select for the evolution of increased toxin production by plants and increased counterdefenses by herbivores via their positive effects on plant population growth. Unless toxins directly affect pollinator foraging, plants always evolve increases in attraction and defense traits when they interact with both kinds of foragers. This work highlights the value of incorporating ecological dynamics to understand the entangled evolution of mutualisms and antagonisms in natural communities.
    • Doing film geography

      Lukinbeal, Chris; Sommerlad, Elisabeth; Department of Geography, Development and the Environment, University of Arizona (Springer Science and Business Media LLC, 2022-04-27)
      Film geography as a subdiscipline of cultural and media geography is a long-established field of research that since its emergence more than twenty years ago has diversified into a variety of perspectives. Nowadays, a critical perspective on film is central, which no longer considers the medium merely as a text, but rather as a social practice—a perspective that continues to focus not solely on the meaning of representations, but on what representations do and how they do it. Following Roberts’ (in: Edensor, Kalandides, Kothari (eds) The Routledge handbook of place, Routledge, London, 2020) call for ‘doing film geography,’ this introductory article to the Geojournal Special Issue on Film Geography provides an overview of current trends in the field as well as an overview of the essays included in this collection. In addition to the established film-as-text perspective, we examine the burgeoning research in cinematic cartography, film industry geographies, and videography/documentaries.
    • Less Than Fully Honest: Financial Deception in Emerging Adult Romantic Relationships

      Saxey, Matthew T.; LeBaron-Black, Ashley B.; Dew, Jeffrey P.; Curran, Melissa A.; University of Arizona (SAGE Publications, 2022-04-26)
      Emerging adults lack many basic financial capabilities. To avoid conflict that may come from these deficiencies, some emerging adults may financially deceive their romantic partner. However, little is known about financial deception in emerging adult romantic relationships. Through the lenses of two theoretical frameworks, we test whether financial deception intervenes the associations of couple financial communication, financial socialization, and similarity of financial values with romantic relationship flourishing in a sample of 1,950 U.S. emerging adults. Results indicate that couple financial communication, similarity of financial values, and financial socialization may contribute positively toward romantic relationship flourishing. However, financial socialization and financial deception may contribute negatively toward romantic relationship flourishing. Findings are discussed in light of the theoretical frameworks utilized, implications for clinicians and educators are identified, and directions for future research are presented. In summary, being less than fully honest about finances may have implications for emerging adults in romantic relationships.
    • Sexual Minority Stressors and Intimate Partner Violence Among Same-Sex Couples: Commitment as a Resource

      Li, Xiaomin; Curran, Melissa A.; Butler, Emily; Mills-Koonce, W. Roger; Cao, Hongjian; Department of Family Studies and Human Development, University of Arizona (Springer Science and Business Media LLC, 2022-04-25)
      Accumulating evidence has been found for the associations from sexual minority stressors to intimate partner violence (IPV) among same-sex couples. Yet key gaps still exist, including the rare utilization of couple dyadic data, the understudied moderating and mediating mechanisms, and the few studies conducted during the transitional period of same-sex marriage legalization. To address these gaps, we used cross-sectional, dyadic data collected from 144 US same-sex couples during the 2014–2015 national campaign for the legalization of same-sex marriage. Guided by the systemic transactional model (STM), we examined associations from sexual minority stressors (including both internalized homophobia and discrimination) to same-sex IPV and tested whether commitment moderated or mediated these associations. Overall, we found evidence supporting the STM: (1) High internalized homophobia and discrimination were related to high prevalence and/or frequency of IPV perpetration; (2) high commitment attenuated positive associations between high discrimination and high prevalence and/or frequency of IPV perpetration; and (3) high internalized homophobia was related to low commitment, which in turn was related to high prevalence and/or frequency of IPV perpetration. Collectively, our study identified commitment as both a moderator and mediator in associations from sexual minority stressors to same-sex IPV. Further, the roles of commitment (i.e., moderator or mediator) depend on whether the focal sexual minority stressors are distal and more intermittent (i.e., heterosexist discrimination) or proximal and more constant (i.e., internalized homophobia).