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These collections include publications and data from University of Arizona faculty, staff and researchers. The UA Faculty Publications collection consists primarily of open access versions of published journal articles, but also contains conference proceedings and other unique materials from faculty, staff and researchers. Organizational collections, such as the College of Agricultural and Life Sciences Publications, and Water Resources Research Center, contain additional faculty publications such as departmentally produced technical bulletins, technical reports, and working papers.
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Resisting Privilege: Effects of a White Privilege Message Intervention and Conservative Media Use on Freedom Threat and Racial AttitudesIdentifying ways to effectively communicate about racial/ethnic disparities is a place where communication scholars can make vital contributions. Yet, existing studies on this subject are scarce. Borrowing from reactance theory and the 3D model of White identity management, the present study tested whether exposing White adults to White privilege messaging helps them to become more aware or deny racial privilege. The results of our experiment revealed that there was a main effect for reading about racial privilege and increased awareness of privilege. However, in keeping with reactance theory, if the message stoked a perceived threat to freedom, message exposure resulted in the denial of both blatant and institutional racism. We also found a moderating role for Fox News viewing such that awareness of racial privilege was not affected by the intervention for heavy Fox News viewers, but it was for low Fox News viewers. We conclude that messages focused on explaining White privilege are promising, but there are risks.
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The moderating role of mystical-type experiences on the relationship between existential isolation and meaning in lifeMystical-type experiences (MTEs) are unique phenomenological experiences that are often reported to induce significant and persisting changes in the experiencer's worldview. Previous research suggests that higher levels of existential isolation (EI) are associated with lower levels of meaning in life (MIL). This study examines the hypothesis that people who have had an MTE (compared with those who have not) will not show such a relationship between EI and MIL. Data from two samples (N = 2055) support the idea that those who have not had an MTE show a negative relationship between EI and MIL while those who have had an MTE show no relationship between EI and MIL. Implications and future directions are discussed.
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Conformal 3D printing of non-planar antennas on wrinkled and folded kapton films using point cloud dataWe report a reverse engineering-driven method for conformal microextrusion three-dimensional (3D) printing of functional materials on complex 3D structures and thin films of near-arbitrary topography. A non-planar tool path programming algorithm for conformal microextrusion 3D printing based on point cloud data representations of object geometry is presented. We show that the optimal nozzle-substrate standoff distance for quality 3D printing depends on the substrate's local geometric features (i.e. slope and curvature) and the tool trajectory. The impact and utility of the novel conformal microextrusion 3D printing process were demonstrated by fabrication of 3D spiral and Hilbert-curve loop antennas on various non-planar substrates, including wrinkled and folded Kapton films and origami. 3D-printed conformal antennas exhibited resonant frequencies ranging from 1.5 to 2.7 GHz with S11 less than 10 db. This work provides a new method for conformal 3D printing on one-of-a-kind objects and non-planar films.
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Exploring spatial averaging of contamination in fomite microbial transfer models and implications for doseBackground: When modeling exposures from contact with fomites, there are many choices in defining the sizes of compartments representing environmental surfaces and hands, and the portions of compartments involved in contacts. These choices impact dose estimates, yet there is limited guidance for selection of these model parameters. Objective: The study objective was to explore methods for representing environmental surface and hand contact areas in exposure models and implications for estimated doses. Methods: A simple scenario was used: an individual using their hands to contact their face and two microbially contaminated environmental surfaces. Four models were developed to explore different compartmentalization strategies: (1) hands and environmental surfaces each represented by one compartment, (2) hands represented by two compartments (fingertips vs. non-fingertip areas) while environmental surfaces were represented by one compartment, (3) hands represented by a single compartment and environmental surfaces represented by two compartments, and (4) hands and environmental surfaces each represented by two compartments. Sensitivity analyses were conducted to evaluate the influence of heterogeneous surface contact frequency, hand contact type, and hand dominance on dose. Results: Estimated doses were greatest when hand areas and environmental surfaces were each represented by two compartments, indicating that surface area “dilutes” contaminant concentration and decreases estimated dose. Significance: Model compartment designations for hands and environmental surfaces affect dose estimation, but more human behavior data are needed. Impact statement: A common problem for exposure models describing exposures via hand-to-surface contacts occurs in the way that estimated contamination across human skin (usually hands) or across environmental surfaces is spatially averaged, as opposed to accounting for concentration changes across specific parts of the hand or individual surfaces. This can lead to the dilution of estimated contaminants and biases in estimated doses in risk assessments. The magnitude of these biases and implications for the accuracy in risk assessments are unknown. We quantify differences in dose for various strategies of compartmentalizing environmental surfaces and hands to inform guidance on future exposure model development.
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Couple-Level Attachment Styles, Finances, and Marital Satisfaction: Mediational Analyses Among Young Adult Newlywed CouplesGuided by attachment theory and the Vulnerability-Stress-Adaptation model, we used three-annual-wave, dyadic data from a nationally representative sample of 1136 young-adult newlywed couples to investigate two research aims. First, we conducted a Latent Profile Analysis to identify couple-level attachment styles at Time 1 (i.e., within the first 2 years of marriage) based on the combination of husbands’ and wives’ attachment anxiety and attachment avoidance. Second, after conceptualizing couple-level attachment styles at Time 1 as vulnerability, we then examined whether finance-specific adaptive processes at Time 2 (i.e., 1 year after Time 1) mediated associations from couple-level attachment styles at Time 1 to marital satisfaction at Time 3 (i.e., 1 year after Time 2). Several findings are noteworthy. First, four different types of couple-level attachment styles were found. Second, for mediators, only perceived partner financial mismanagement mediated associations from couple-level attachment styles at Time 1 to marital satisfaction at Time 3. We discuss how the four different couple-level styles highlight the diversity and complexity in how the two partners’ attachment anxiety and attachment avoidance combine together as well as why perceived partner financial mismanagement (i.e., the lack of adaptive processes) mediated associations between couple-level attachment styles and marital satisfaction.
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Quasi-static and dynamic behavior of additively manufactured lattice structures with hybrid topologiesWhen different unit cell topologies with distinct mechanical behavior (e.g. bending vs stretching dominated) are incorporated into a single hybrid lattice structure (LS), questions arise about the resolution of local stresses within the struts and how localized states of strain as a result govern the global response of the structure. To understand the mechanics of hybrid LS, this study uses a combination of experimental and modeling data to investigate the relationship between localized states of stress with the global behavior of hybrid additive manufactured lattice structures (AMLS) under different loading directions and strain rates. The hybrid AMLS in this study consist of two different unit cell topologies stacked in alternating rows, with loading directions identified with respect to this topology stacking. It is shown that the loading direction influences the mechanical behavior, as the flow stress of the hybrid AMLS is 7%–10% lower when loaded in the stacking direction than when loaded in the transverse direction. This flow stress decrease is due to a smaller number of structural elements supporting the loading and tensile failure of horizontally-manufactured struts in the stacking direction. The strain rate also influenced the mechanical behavior of the AMLS, as irrespective to the loading direction, for all hybrid AMLS, the first peak stress after static equilibrium is 5%–10% higher under dynamic loading compared to quasi-static loading. Additionally, it is shown that the collapse mechanisms are influenced by the order of the topology stacking. Structural shear band formation, which leads to up to a 60% drop in flow stress under dynamic loading of the hybrid AMLS, can be inhibited by separating adjacent rows of shear band-forming topologies with a row of unit cells of a topology which does not form shear bands. Ultimately, it was determined that the performance of these layered structures is limited by the weakest topology. Even under transverse loading, where the first peak stress approaches that of the stronger topology, the magnitude of the subsequent decrease in flow stress is generally more in line with that of the weaker topology.
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Parametric stability of geared systems with linear suspension in permanent contact regimeThe prediction and control of excessive vibration are one of the most important concerns in the design and development of geared systems. For any gear set, parametric resonance is the main source of instability, resulting in the separation of gears in mesh and chaotic behavior. In many works, gears are modeled with rigid mountings, and various analytical and numerical approaches have been used to investigate the dynamic characteristics of the system in different regimes: permanent contact (no impact), free play, single-sided impact, and double-sided impact. Alternatively, in other works, the effect of the deformation of the mountings is included in the dynamic modeling; in almost all these studies, the dynamic characteristic of the system is investigated through direct numerical integration of the governing differential equations, and there is no analytical work to determine the effect of suspension on the parametric resonance of the system. Consequently, in this work, both analytical and numerical approaches, including the Poincare–Lindstedt method and Floquet theory, are used to investigate the dynamic characteristics of a one-stage spur gear pair with linear suspension in the permanent contact regime. It has been shown that, unlike systems with rigid mounting that have one set of unstable tongues, systems with suspension have three sets of unstable tongues. The results show that the additional sets of unstable tongues appear at higher parametric frequencies. Therefore, the rigid mounting assumption is accurate only for systems operating at low speeds; for systems operating at high speeds, the deformation of the suspension must be included in the dynamic modeling, as it significantly contributes to the parametric instability of the system.
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Limitations of clinical trial sample size estimate by subtraction of two measurementsIn planning randomized clinical trials (RCTs) for diseases such as Alzheimer's disease (AD), researchers frequently rely on the use of existing data obtained from only two time points to estimate sample size via the subtraction of baseline from follow-up measurements in each subject. However, the inadequacy of this method has not been reported. The aim of this study is to discuss the limitation of sample size estimation based on the subtraction of available data from only two time points for RCTs. Mathematical equations are derived to demonstrate the condition under which the obtained data pairs with variable time intervals could be used to adequately estimate sample size. The MRI-based hippocampal volume measurements from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and Monte Carlo simulations (MCS) were used to illustrate the existing bias and variability of estimates. MCS results support the theoretically derived condition under which the subtraction approach may work. MCS also show the systematically under- or over-estimated sample sizes by up to 32.27 (Formula presented.) bias. Not used properly, such subtraction approach outputs the same sample size regardless of trial durations partly due to the way measurement errors are handled. Estimating sample size by subtracting two measurements should be treated with caution. Such estimates can be biased, the magnitude of which depends on the planned RCT duration. To estimate sample sizes, we recommend using more than two measurements and more comprehensive approaches such as linear mixed effect models.
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Some displays of lens structural performanceSome useful displays that provide information about the performance of lens systems are presented and discussed in this paper. They are useful for comparing lenses, identifying problematic lens elements, and lens desensitizing and optimizing. An imaging simulation of a square wave is also presented to complement the modulation transfer function plots.
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C-terminal modified Enkephalin-like tetrapeptides with enhanced affinities at the kappa opioid receptor and monoamine transportersA new series of enkephalin-like tetrapeptide analogs modified at the C-terminus by an N-(3,4-dichlorophenyl)-N-(piperidin-4-yl)propionamide (DPP) moiety were designed, synthesized, and tested for their binding affinities at opioid receptors and monoamine transporters to evaluate their potential multifunctional activity for the treatment of chronic pain. Most ligands exhibited high binding affinities in the nanomolar range at the opioid receptors with a slight delta-opioid receptor (DOR) selectivity over mu-opioid receptor (MOR) and kappa-opioid receptor (KOR) and low binding affinities in the micromolar range at the monoamine transporters, SERT and NET. Ligands of which the positions 1 and 4 were substituted by Dmt and Phe(4-X) residues, respectively, showed the excellent binding affinities at three opioid receptors. Among them, Dmt-D-Tic-Gly-Phe(4-F)-DPP was the most promising considering its excellent opioid affinities, particularly unexpected high binding affinity (Ki = 0.13 nM) at the KOR, and moderate interactions with serotonin/norepinephrine reuptake inhibitors (SNRIs). Docking studies revealed that the ligand was a good fit for the KOR binding pocket (binding score = 8,750).
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Middle to late Miocene growth of the North PamirHow and when the Pamir formed remains an open question. This study explores Pamir tectonics recorded in a sedimentary section in the eastern Tajik Basin. A prominent lithofacies change that has been recognised regionally is assigned to the middle Miocene (13.5 Ma based on preferred magnetostratigraphic correlation). Closely following this change, detrital zircon U-Pb age spectra and mudstone bulk-rock εNd values exhibit a sediment source change from the Central to the North Pamir estimated ca. 12 Ma. At the same time, the stable oxygen and carbon isotopic values of carbonate cements show negative and positive shifts, respectively. Combined with previous studies in both the Tajik and Tarim basins, these results suggest that the North Pamir experienced a middle–late Miocene phase of deformation and surface uplift. This supports models proposing middle–late Miocene Pamir tectonism, and climate models implying that coeval Pamir orogenesis deflected Westerly moisture and affected Asian environments.
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Phase Retrieval in Tabletop Radar RangeWe are describing the capability to measure the phase of the return signal in a tabletop radar range. The radar rage has a scale factor of 100,000 which allows to use near IR wavelength instead of radio frequency. Accurate scale models are manufactured using multiphoton 3D printer with nanometric resolution. We demonstrated that using phase shifting interferometry, this radar range can retrieve the phase of the radar cross section of complex objects similar to SAR or ISAR radar systems.
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Extending the life of water reuse reverse osmosis membranes using chlorinationNumerous efforts have been made over the years to extend the lifespan of reverse osmosis (RO) membranes. End-of-life RO membranes are periodically replaced and usually discarded in landfills. Periodic membrane modification using chlorination may be an alternative to recover their productivity without compromising process safety. In this research, RO membranes from an engineering-scale ultrafiltration-RO system treating reclaimed water were exposed five times to 2000 ppm-h of chlorine immediately after chemical cleaning. Water, conductivity, ion, and organic permeability coefficients and rejection were related to the chlorine dose. The breakthrough of six naturally occurring viruses with different levels of persistence to wastewater treatment was also monitored. After five chlorine doses, the apparent water permeability was recovered to 1.0–1.5 L m−2 h−1 bar−1, a 3.1-fold increase compared to the end-of-life membranes, with only a 2% decrease in observed salt rejection. Interestingly, apparent conductivity and ion permeability slightly decreased after the first and second chlorine dose, likely because the chlorine removed irreversible fouling/scaling and thus reduced concentration polarization. After the third chlorine dose, as the RO membrane surface oxidized, more monovalent ions permeated through the membrane, while observed divalent ion rejection remained relatively high and constant (>97%). Similarly, the RO permeate dissolved organic carbon concentration and total fluorescence intensity decreased between end-of-life membrane and the second chlorine dose, followed by an increase after the third dose, and only humic substances and building block compounds (<2 kDa) were detected. All viruses were below or near the detection limit, indicating that oxidation did not compromise the integrity of the membrane in its ability to reject virus-sized particles. The results suggest that targeted chlorination may extend RO membrane lifespan by increasing apparent water permeability while maintaining RO-like selectivity.
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Investigating Predictability of DIC and SST in the Argentine Basin Through Wind Stress Perturbation ExperimentsThe confluence of the Malvinas and Brazil currents over the Argentine Basin give the region chaotic dynamics and severely limit potential predictability. To probe the forecast horizon for ocean surface quantities of temperature and carbon, we construct regional models of the Argentine Basin with biogeochemistry at 1/3° and 1/12° resolution and design a series of experiments. We add positive and negative zonal wind stress anomalies over small and large areas during a short period in different model runs. We calculate the response of the surface temperature and DIC. The 1/3° model maintains predictability for up to 45 days, while the 1/12° model has a shorter window of about two weeks. However, the 1/3° model response is only consistent with the 1/12° model for about 8 days calling into question the potential predictive skill of the coarser model at longer lead times.
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Office Chitchat as a Social Ritual: The Uplifting Yet Distracting Effects of Daily Small Talk at WorkSmall talk-trivial communication not core to task completion-is normative and ubiquitous in organizations. Although small talk comprises up to one-third of adults' speech, its effects in the workplace have been largely discounted. Yet, research has suggested that small talk may have important consequences for employees. Integrating theories of interaction rituals and microrole transitions, we explore how and why seemingly inconsequential workday conversations meaningfully impact employees' experiences. In a sample of employed adults, we used an experience sampling method to capture within-individual variation in small talk over a three-week period. Given that we are the first to examine small talk as an episodic phenomen on, we also conducted a validation of our daily small talk measure with master's students and two samples of employed adults. Using multilevel pathanalysis, results show that small talk enhanced employees' daily positive social emotions at work, which heightened organizational citizenship behaviors (OCB) and enhanced well-being at the end of the workday; furthermore, small talk disrupted employees' ability to cognitively engage in their work, which compromised their OCB. Additionally, higher levels of trait-level self-monitoring mitigated negative effects of small talk on work engagement. Combined, results suggest that the polite, ritualistic, and formulaic nature of small talk is uplifting yet also distracting. © 2021 Academy of Management Journal.
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Practical Limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon NoiseAccurate and stable spacecraft pointing is a requirement of many astronomical observations. Pointing particularly challenges nanosatellites because of an unfavorable surface area–to-mass ratio and a proportionally large volume required for even the smallest attitude control systems. This work explores the limitations on astrophysical attitude knowledge and control in a regime unrestricted by actuator precision or actuator-induced disturbances such as jitter. The external disturbances on an archetypal 6U CubeSat are modeled, and the limiting sensing knowledge is calculated from the available stellar flux and grasp of a telescope within the available volume. These inputs are integrated using a model-predictive control scheme. For a simple test case at 1 Hz, with an 85-mm telescope and a single 11th magnitude star, the achievable body pointing is predicted to be 0.39 arcseconds. For a more general limit, integrating available star light, the achievable attitude sensing is approximately 1 milliarcsecond, which leads to a predicted body pointing accuracy of 20 milliarcseconds after application of the control model. These results show significant room for attitude sensing and control systems to improve before astrophysical and environmental limits are reached. © Copyright © 2021 Douglas, Tracy and Manchester.
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Small Mirrors for Small Satellites: Design of the Deformable Mirror Demonstration Mission CubeSat (DeMi) PayloadThe Deformable Mirror Demonstration Mission (DeMi) is a technology demonstration CubeSat to test a 140 actuator micro-electromechanical system (MEMS) deformable mirror in low-Earth orbit. Such mirrors can provide precise wavefront control with low size, weight, and power per actuator. Hence, they have the potential of improving contrast in coronagraphs on future space telescopes. In the DeMi payload, a Shack Hartmann lenslet array based wavefront sensor monitors the deformable mirror, illuminated by either an internal 636 nm laser diode or external starlight. This work describes the instrument design drivers and CubeSat implementation, and briefly illustrates operation on orbit by comparing ground-based measurements of a displaced actuator to an on-orbit measurement using the internal laser source. The 6U CubeSat was launched on February 25, 2020 and deployed from the International Space Station on July 13, 2020. © Copyright © 2021 Douglas, Allan, Morgan, Holden, Gubner, Haughwout, do Vale Pereira, Xin, Merk and Cahoy.
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Magnetic Field Reconstruction for a Realistic Multi-Point, Multi-Scale Spacecraft ObservatoryFuture in situ space plasma investigations will likely involve spatially distributed observatories comprised of multiple spacecraft, beyond the four and five spacecraft configurations currently in operation. Inferring the magnetic field structure across the observatory, and not simply at the observation points, is a necessary step towards characterizing fundamental plasma processes using these unique multi-point, multi-scale data sets. We propose improvements upon the classic first-order reconstruction method, as well as a second-order method, utilizing magnetometer measurements from a realistic nine-spacecraft observatory. The improved first-order method, which averages over select ensembles of four spacecraft, reconstructs the magnetic field associated with simple current sheets and numerical simulations of turbulence accurately over larger volumes compared to second-order methods or first-order methods using a single regular tetrahedron. Using this averaging method on data sets with fewer than nine measurement points, the volume of accurate reconstruction compared to a known magnetic vector field improves approximately linearly with the number of measurement points. © Copyright © 2021 Broeren, Klein, TenBarge, Dors, Roberts and Verscharen.
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Modeling in-process machining data using spatial point cloud vs. Time series data structuresIn-process machining data (e.g., cutting forces and vibrations) have been typically collected and structured as time-referenced measurements (i.e., time-series data) and utilized in this structure to develop statistical data models used in process monitoring and control methods. This paper argues that a time-only-referenced representation overlooks the 3D nature of the physical process generating the data, and that machining data can be represented alternatively as functions of the tool-workpiece relative position resulting in a spatial point cloud data structure. High-density measurements of such spatially refenced data could be highly correlated to surrounding measurements, resulting in spatial correlation structures that could be of physical meaning and value to preserve and leverage. Using a simulated data study, this paper shows that preserving the spatial correlation structure of the data clearly improves the relative modeling performance when utilizing machining data point clouds versus the traditional time-referenced data structure. Specifically, this simulation study investigated the hypothesis that “considering the Gaussian process model class, the best model among all possible models developed using the spatial point cloud data structure has smaller/equal modeling and prediction errors compared to the best model among all possible models developed using the time-referenced data structure.” While this investigation was limited to considering the case of stationary isotropic processes, it demonstrated that the performance gap was relatively large. This encourages further investigations using real-world data to better understand the types of spatial correlations that exist in machining data and the specific machining regimes and process variables that would benefit the most from the spatial point cloud representation of the data. © 2021 The Authors. Published by Elsevier B.V.
