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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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  • Snowtography quantifies effects of forest cover on net water input to soil at sites with ephemeral or stable seasonal snowpack in Arizona, USA

    Dwivedi, Ravindra; Biederman, Joel A.; Broxton, Patrick D.; Lee, Kangsan; van Leeuwen, Willem J. D.; School of Natural Resources and the Environment, The University of Arizona; School of Geography, Development and Environment, The University of Arizona (Wiley, 2022-11-08)
    Forested, snow-dominated watersheds provide a range of ecosystem services including water supply, carbon sequestration, habitat and recreation. While hydrologic partitioning has been well-studied in watersheds with stable seasonal snowpack, less is known about watersheds with ephemeral snowpack. Furthermore, drought-related disturbances and/or management practices are altering vegetation cover in many forests, with unknown and potentially different, consequences for stable seasonal versus ephemeral snowpacks. This study quantifies net water input (NWI) to soil for two sites with contrasting stable seasonal and ephemeral snowpacks, respectively, for three water years in Arizona, USA. Observations include a network of automated cameras and graduated snow stakes (snowtography) deployed across gradients of forest structure, airborne lidar maps of topography and forests and SNOTEL station records. Given the importance of mixed-phase precipitation in ephemeral snowpack watersheds, an algorithm is developed to distinguish among snowfall and rainfall that does/does not contribute to snowpack mass. Finally, existing canopy interception and snowpack models are used to estimate how NWI varies with canopy cover. At the ephemeral snowpack site, increasing canopy cover reduces NWI amount and advances its seasonal timing less strongly than at the stable seasonal snowpack site. Interestingly, canopy reduces NWI duration at the ephemeral site but prolongs it at the stable seasonal snowpack site. These effects are more important in a cool/wet and average year than a warm/dry year. Understanding differences between canopy impacts on amount, timing and duration of NWI for areas with ephemeral versus stable seasonal snowpack is increasingly important as the number of watersheds with ephemeral snowpack grows.
  • Affection deprivation is more aversive than excessive affection: A test of affection exchange theory

    Hesse, Colin; Floyd, Kory; Mikkelson, Alan C.; Department of Communication, University of Arizona (Wiley, 2022-11-02)
    Affection exchange theory predicts that both excessive affection and affection deprivation are associated with poorer health, compared with receiving the level of affectionate communication that one desires. A similar yet-untested prediction is that affection deprivation is more aversive than excessive affection. This preregistered study tested both hypotheses on a battery of mental and physical health outcomes, including depression, loneliness, stress, physical pain, frequency of nightmares, and sleep quality, using a Census-matched sample of U.S. American adults (N = 827). As hypothesized, receiving the right amount of affection was associated with more health-supportive scores on all outcomes than either excessive or deficient affection. Similarly, excessive affection was associated with lower depression, loneliness, stress, and pain, and higher sleep quality, than affection deprivation.
  • A Halogen Record of Fluid Activity in the Solar System

    Barnes, Jessica J.; Zolensky, Michael E.; University of Arizona, Lunar and Planetary Laboratory (Mineralogical Society of America, 2022-02-01)
    Halogens are mobile in geological fluids, making them excellent tracers of volatile activity. Halogen-bearing minerals in diverse planetary materials, coupled with chlorine isotope compositions of bulk samples and minerals, can be used to infer the presence of fluids on planetary surfaces, crusts, and interiors. Halogen element and isotopic evidence helps define the role that halogens play in diverse planetary environments (e.g., asteroids, the Moon, and Mars), which offers insights into fluid activity in the early Solar System and in the role such fluids have played in volatile transport, alteration processes, and habitability throughout geological history.
  • Eu@C88 Isomers: Calculated Relative Populations

    Uhlík, Filip; Slanina, Zdeněk; Bao, Lipiao; Akasaka, Takeshi; Lu, Xing; Adamowicz, Ludwik; Department of Chemistry and Biochemistry, University of Arizona (Institute of Physics, 2022-10-17)
    Relative populations of three energy-lowest IPR (isolated-pentagon-rule) isomers of Eu@C88 are computed using the Gibbs energy based on characteristics from density functional theory and MP2 calculations (M06-2X/3-21G∼SDD entropy term, and the MP2=FU/6-31G*∼SDD or B2PLYPD=FU/6-31 + G*∼SDD energetics). The calculations predict coexistence of three isomers, in agreement with extraction using a polar solvent, and offer a possible explanation why the Eu@C 2(27)-C88 species should prevail with a non-polar solvent. Role of extraction solvents and catalysis is thus pointed out.
  • Empirical assessment of fragility index based on a large database of clinical studies in the Cochrane Library

    Xing, Aiwen; Lin, Lifeng; Department of Epidemiology and Biostatistics, University of Arizona (John Wiley and Sons Inc, 2022-11-02)
    Rationale Aims and Objectives: The fragility index (FI) and fragility quotient (FQ) are increasingly used measures for assessing the robustness of clinical studies with binary outcomes in terms of statistical significance. The FI is the minimum number of event status modifications that can alter a study result's statistical significance (or nonsignificance), and the FQ is calculated as the FI divided by the study's total sample size. The literature has no widely recognized criteria for interpreting the fragility measures' magnitudes. This article aims to provide an empirical assessment for the FI and FQ based on a large database of clinical studies in the Cochrane Library. Methods: We explored the overall empirical distributions of the FI and FQ based on five common methods (Fisher's exact test, χ2 test, risk difference, odds ratio, and relative risk) for determining statistical significance of binary outcomes in clinical research. We also considered three different scenarios for the FI calculation and evaluated the relationship between p values and FIs or FQs using Spearman's (Formula presented.). Finally, we summarized empirical thresholds based on the overall distributions of the FI and FQ to facilitate their interpretations in future research. Results: For about 20% of studies with significant results, the statistical significance was changed after modifying the event status of only one participant. Studies with significant results were considered slightly fragile if the significance hinged on the statuses of about five events. Studies were extremely fragile if FI (Formula presented.) 1 or FQ (Formula presented.) 0.01. The FIs were strongly correlated with p values for significant studies, while Spearman's (Formula presented.) varied according to the total sample sizes of studies. Conclusions: The statistical significance of clinical studies could be changed after modifying a few events' statuses. Many studies' findings are fairly fragile. The distributions of the FI and FQ provide insights for appraising the robustness of evidence in clinical decision-making.
  • Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna

    Wells, Harry B. M.; Crego, Ramiro D.; Alston, Jesse M.; Ndung'u, S. Kimani; Khasoha, Leo M.; Reed, Courtney G.; Hassan, Abdikadir A.; Kurukura, Samson; Ekadeli, Jackson; Namoni, Mathew; et al. (Wiley, 2022-10-27)
    Whether wild herbivores confer biotic resistance to invasion by exotic plants remains a key question in ecology. There is evidence that wild herbivores can impede invasion by exotic plants, but it is unclear whether and how this generalises across ecosystems with varying wild herbivore diversity and functional groups of plants, particularly over long-term (decadal) time frames. Using data from three long-term (13- to 26-year) exclosure experiments in central Kenya, we tested the effects of wild herbivores on the density of exotic invasive cacti, Opuntia stricta and O. ficus-indica (collectively, Opuntia), which are among the worst invasive species globally. We also examined relationships between wild herbivore richness and elephant occurrence probability with the probability of O. stricta presence at the landscape level (6150 km2). Opuntia densities were 74% to 99% lower in almost all plots accessible to wild herbivores compared to exclosure plots. Opuntia densities also increased more rapidly across time in plots excluding wild herbivores. These effects were largely driven by megaherbivores (≥1000 kg), particularly elephants. At the landscape level, modelled Opuntia stricta occurrence probability was negatively correlated with estimated species richness of wild herbivores and elephant occurrence probability. On average, O. stricta occurrence probability fell from ~0.56 to ~0.45 as wild herbivore richness increased from 6 to 10 species and fell from ~0.57 to ~0.40 as elephant occurrence probability increased from ~0.41 to ~0.84. These multi-scale results suggest that any facilitative effects of Opuntia by wild herbivores (e.g. seed/vegetative dispersal) are overridden by suppression (e.g. consumption, uprooting, trampling). Synthesis. Our experimental and observational findings that wild herbivores confer resistance to invasion by exotic cacti add to evidence that conserving and restoring native herbivore assemblages (particularly megaherbivores) can increase community resistance to plant invasions.
  • International regulatory diversity over 50 years: Political entrepreneurship within fiscal constraints

    Tarko, Vlad; Safner, Ryan; Department of Political Economy and Moral Science, University of Arizona (Springer Science and Business Media LLC, 2022-10-29)
    Over the last 50 years, economic freedom in modern capitalist democracies has increased although the regulatory state has expanded considerably, resulting in the paradox of “freer markets, more rules” (Vogel, 1996). We provide a hierarchical cluster analysis of the policy trajectories of OECD countries over the last 50 years, as well as a theoretical framework that builds on Stigler’s (1971) theory of economic regulation. Our findings suggest that these developments are not the result of ideological narratives such as “neoliberalism,” but instead we confirm some claims from the “varieties of capitalism” and “regulatory capitalism” literatures using independent methods. Our approach is better able to explain the diversity of regulatory regimes across countries than existing approaches that focus on either national patterns or policy sectors, and we also provide a fuller account of government crowding-out and crowding-in effects across the entire structure of production.
  • Psychological Distress, Destructive Conflict, and Parenting among Residential and Nonresidential Fathers

    Kopystynska, Olena; Barnett, Melissa A.; Bradford, Kay; Crapo, J. Scott; Higginbotham, Brian; Family Studies and Human Development, The University of Arizona (Informa UK Limited, 2022-11-04)
    We utilized the Determinants of Parenting process model to examine correlates of paternal parenting by father’s residential status. Data consisted of fathers (N = 1,784) who participated in a federally funded Responsible Fatherhood program. Study variables were assessed through fathers’ self-reports. Using a structural equation modeling framework, the results of multi-group analyses revealed differences in parenting by father’s residential status. For residential fathers, both psychological distress and destructive conflict related to less nurturance and involvement, and destructive conflict was a mechanism through which psychological distress promoted harsh parenting. Nonresidential fathers were less involved when destructive conflict was present. These findings underscore fathers’ sensitivity to the context of interpersonal relationships and suggest that fatherhood education programs address the needs of both residential and nonresidential fathers.
  • Flow rate profile based PFAS detection on smartphone- and paper-based microfluidics

    Yoon, Jeong-Yeol; Breshears, Lane E.; Mata-Robles, Samantha; Reynolds, Kelly A.; University of Arizona, Department of Biomedical Engineering; University of Arizona, Mel and Enid College of Public Health (IEEE, 2022-09)
    Sensitive detection of PFOA, type of PFAS (perfluorinated-alkyl substances), was demonstrated on paper-based microfluidic chip utilizing competitive binding with albumin or casein and cellulose fibers. It altered the capillary flow rate profile and monitored by a smartphone camera. Detection limit was 1-10 fg/μL (1-10 ppt).
  • Sleep Efficiency and Naturalistically-Observed Social Behavior Following Marital Separation: The Critical Role of Contact With an Ex-Partner

    Coppola, Andrea M.; Mehl, Matthias R.; Tackman, Allison M.; Dawson, Spencer C.; O’Hara, Karey L.; Sbarra, David A.; Department of Psychology, University of Arizona (SAGE Publications, 2022-10-22)
    Marital disruption is associated with increased risk for a range of poor health outcomes, including disturbed sleep. This report examines trajectories of actigraphy-assessed sleep efficiency following marital separation as well as the extent to which daily social behaviors and individual differences in attachment explain variability in these trajectories over time. One hundred twenty-two recently-separated adults (N = 122) were followed longitudinally for three assessment periods over 5 months. To objectively assess daily social behaviors and sleep efficiency, participants wore the Electronically Activated Recorder (EAR) during the day (for one weekend at each assessment period) and an actiwatch at night (for 7 days at each assessment period). Greater time spent with an ex-partner, as assessed by the EAR, was associated with decreased sleep efficiency between participants (p =.003). Higher attachment anxiety was also associated with decreased sleep efficiency (p =.03), as was the EAR-observed measure of “television on.” The latter effect operated both between (p =.004) and within participants (p =.005). Finally, study timepoint moderated the association between EAR-observed television on and sleep efficiency (p =.007). The current findings deepen our understanding of sleep disturbances following marital separation and point to contact with an ex-partner and time spent with the television on as behavioral markers of risk.
  • Effective non-pharmaceutical approaches to restorative sleep for healthcare professionals

    Newman, Madison; Alschuler, Lise; University of Arizona College of Medicine; Andrew Weil Center for Integrative Medicine, University of Arizona (Elsevier BV, 2022-12)
    Sleep, one of the foundations of health, is regulated by homeostatic sleep drive and circadian rhythm. Poor sleep has a variety of consequences, and healthcare professionals are particularly susceptible to poor sleep patterns due to stress and time restraints. Sleep health can be improved through diet and a balanced nighttime snack, morning aerobic exercise, nighttime yoga and progressive muscle relaxation meditations, full spectrum light therapy in the mornings, and dietary supplements such as valerian, melatonin, and magnesium, which are shown to improve sleep quality and are safer alternatives to sedative pharmaceuticals. These strategies can be effective in creating better sleep with relatively small changes leading to big differences.
  • RGLS and RLS in Covariance Structure Analysis

    Zheng, Bang Quan; Bentler, Peter M.; University of Arizona (Informa UK Limited, 2022-10-31)
    This paper assesses the performance of regularized generalized least squares (RGLS) and reweighted least squares (RLS) methodologies in a confirmatory factor analysis model. Normal theory maximum likelihood (ML) and generalized least squares (GLS) statistics are based on large sample statistical theory. However, ML and GLS goodness-of-fit tests often make incorrect decisions on the true model, when sample size is small. The novel methods RGLS and RLS aim to correct the over-rejection by ML and under-rejection by GLS. Both methods outperform ML and GLS when samples are small, yet no studies have compared their relative performance. A Monte Carlo simulation study was carried out to examine the statistical performance of these two methods. We find that RLS and RGLS have equivalent performance when N (Formula presented.) 70; whereas when N (Formula presented.) 70, RLS outperforms RGLS. Both methods clearly outperform ML and GLS with N (Formula presented.) 400. Nonetheless, adopting mean and variance adjusted test for non-normal data, RGLS slightly outperforms RLS. Power analyses found that RLS generally showed small loss in power compared to ML and performed better than RGLS.
  • Acute Hospital Outcomes for Renal Transplantation in Patients With Moderate or Severe Congenital Heart Disease

    Patel, Surbhi B.; Webber, Zak; Strah, Danielle D.; Hellinger, Riley D.; Yrun-Duffy, Macken; Kowalek, Katie A.; Seckeler, Michael D.; College of Medicine, University of Arizona; Medical Scientist Training Program, College of Medicine, University of Arizona; Department of Pediatrics, University of Arizona; et al. (Elsevier BV, 2023-01)
    Children and adults with congenital heart disease (CHD) are increasingly recognized to be at risk for acute and chronic renal injury. Some of these may progress to the need for renal transplantation. We hypothesized that patients with underlying moderate or severe CHD who undergo renal transplantation will have worse acute hospital outcomes. Using a national administrative database, we queried for admissions aged 0 to 50 years with moderate or severe CHD and renal transplantation and compared these to admissions without CHD. There were 56 admissions for renal transplantation in the CHD group (0.04%) and 26,285 admissions in the group without CHD (0.21%, p<0.001). The CHD group were younger, had a higher proportion of Whites, longer length of stay, higher complication rates, higher in-hospital mortality, and higher costs. In conclusion, although renal transplantation is still relatively uncommon in the CHD population, there is an increasing recognition of severe chronic renal disease in the setting of CHD, making it important to understand the potential implications of these findings.
  • Sins of Commission and Omission: The Implications of an Active–Passive Categorization of Counterproductive Work Behavior

    Evans, Jonathan B.; Slaughter, Jerel E.; Ganster, Mahira L.; Department of Management and Organizations, University of Arizona (Springer Science and Business Media LLC, 2022-11-09)
    This paper introduces an active–passive framework to the conceptualization and measurement of counterproductive work behavior (CWB), in order to establish a dimension that categorizes the content of behaviors within the existing interpersonally directed (CWBI) and organizationally directed (CWBO) framework. Doing so provides new insights into the relationship between workplace counterproductivity and sleep. Stressor-emotion models of CWB predict that employees engage in counterproductivity in response to workplace stressors, but extant research suggests that counterproductive behavior increases strain, including reduced sleep quality. We develop a new scale for measuring CWB that differentiates active and passive behaviors and demonstrates the potential for positive intrapsychic consequences for passive CWBI. In Study 1, using five samples, we demonstrate the convergent and discriminant validity, reliability, and acceptable psychometric properties of a 19-item scale that reconceptualizes CWB into four dimensions: active CWBI, passive CWBI, active CWBO, and passive CWBO. In Study 2, using experience-sampling methodology, we found that when employees engage in active CWBO at work in the afternoon they experience reduced sleep quality that evening, whereas engaging in passive CWBI was related to increased sleep quality.
  • Conservation ethics in the time of the pandemic: Does increasing remote access advance social justice?

    Miller-Rushing, Abraham J.; Ellwood, Elizabeth R.; Crimmins, Theresa M.; Gallinat, Amanda S.; Phillips, Molly; Sandler, Ronald L.; Primack, Richard B.; USA National Phenology Network, School of Natural Resources and the Environment, University of Arizona (Elsevier BV, 2022-12)
    The COVID-19 pandemic is stimulating improvements in remote access and use of technology in conservation-related programs and research. In many cases, organizations have intended for remote engagement to benefit groups that have been marginalized in the sciences. But are they? It is important to consider how remote access affects social justice in conservation biology—i.e., the principle that all people should be equally respected and valued in conservation organizations, programs, projects, and practices. To support such consideration, we describe a typology of justice-oriented principles that can be used to examine social justice in a range of conservation activities. We apply this typology to three conservation areas: (1) remote access to US national park educational programs and data; (2) digitization of natural history specimens and their use in conservation research; and (3) remote engagement in conservation-oriented citizen science. We then address the questions: Which justice-oriented principles are salient in which conservation contexts or activities? How can those principles be best realized in those contexts or activities? In each of the three areas we examined, remote access increased participation, but access and benefits were not equally distributed and unanticipated consequences have not been adequately addressed. We identify steps that can and are being taken to advance social justice in conservation, such as assessing programs to determine if they are achieving their stated social justice-oriented aims and revising initiatives as needed. The framework that we present could be used to assess the social justice dimensions of many conservation programs, institutions, practices, and policies.
  • Molecular speciation controls arsenic and lead bioaccessibility in fugitive dusts from sulfidic mine tailings

    Root, Robert A; Chorover, Jon; Department of Environmental Science, University of Arizona; Arizona Laboratory for Emerging Contaminants, University of Arizona (Royal Society of Chemistry, 2022-10-13)
    Communities nearby mine wastes in arid and semi-arid regions are potentially exposed to high concentrations of toxic metal(loid)s from fugitive dusts deriving from impoundments. To assess the relation between potentially lofted particles and human health risk, we studied the relationship between pharmacokinetic bioaccessibility and metal(loid) molecular speciation for mine tailings dust particulate matter (PM), with elevated levels of arsenic and lead (up to 59 and 34 mmol kg-1, respectively), by coupling in vitro bioassay (IVBA) with X-ray absorption spectroscopy (XAS). Mine tailing efflorescent salts (PMES) and PM from the surface crust (0-1 cm, PMSC) and near surface (0-25 cm) were isolated to <10 μm and <150 μm effective spherical diameter (PM10 and PM150) and reacted with synthetic gastric and lung fluid for 30 s to 100 h to investigate toxic metal(loid) release kinetics. Bioaccessible (BAc) fractions of arsenic and lead were about 10 and 100 times greater in gastric than in lung fluid simulant, respectively, and 10-100% of the maximum gastric BAc from PM10 and PM150 occurred within 30 s, with parabolic dissolution of fine, highly-reactive particles followed by slower release from less soluble sources. Evaporite salts were almost completely solubilized in gastric-fluid simulants. Arsenate within jarosite and sorbed to ferrihydrite, and lead from anglesite, were identified by XAS as the principal contaminant sources in the near surface tailings. In the synthetic lung fluid, arsenic was released continuously to 100 h, suggesting that residence time in vivo must be considered for risk determination. Analysis of pre- and post-IVBA PM indicated the release of arsenic in lung fluid was principally from arsenic-substituted jarosite, whereas in synthetic gastric fluid arsenic complexed on ferrihydrite surfaces was preferentially released and subsequently repartitioned to jarosite-like coordination at extended exposures. Lead dissolved at 30 s was subsequently repartitioned back to the solid phase as pyromorphite in phosphate rich lung fluid. The bioaccessibility of lead in surface tailings PM was limited due to robust sequestration in plumbojarosite. Kinetic release of toxic elements in both synthetic biofluids indicated that a single IVBA interval may not adequately describe release dynamics.
  • Natural history of pulmonary coccidioidomycosis: Further examination of the VA-Armed Forces Database

    Shemuel, Joseph; Bays, Derek J; Thompson, George R; Reef, Susan; Snyder, Linda; Freifeld, Alana J; Huppert, Milt; Salkin, David; Wilson, Machelle D; Galgiani, John N; et al. (Oxford University Press, 2022)
    There are still many limitations related to the understanding of the natural history of differing forms of coccidioidomycosis (CM), including characterizing the spectrum of pulmonary disease. The historical Veterans Administration-Armed Forces database, recorded primarily before the advent of antifungal therapy, presents an opportunity to characterize the natural history of pulmonary CM. We performed a retrospective cohort study of 342 armed forces service members who were diagnosed with pulmonary CM at VA facilities between 1955 to 1958, followed through 1966, who did not receive antifungal therapy. Patients were grouped by predominant pulmonary finding on chest radiographs. The all-cause mortality was low for all patients (4.6%). Cavities had a median size of 3-3.9 cm (IQR: 2-2.9–4-4.9 cm), with heterogeneous wall thickness and no fluid level, while nodules had a median size of 1-1.19 cm (Interquartile range [IQR] 1-1.9–2-2.9 cm) and sharp borders. The majority of cavities were chronic (85.6%), and just under half were found incidentally. Median complement fixation titers in both the nodular and cavitary groups were negative, with higher titers in the cavitary group overall. This retrospective cohort study of non-disseminated coccidioidomycosis, the largest to date, sheds light on the natural history, serologic markers, and radiologic characteristics of this understudied disease. These findings have implications for the evaluation and management of CM.
  • The Challenging State of University Campus and Library Open Access Policies

    Johnson, Paula C.; Dubinsky, Ellen; University of Arizona Libraries (Iowa State University, 2022-10-24)
    Introduction: This study investigates whether United States university libraries’ commitment to increasing open access (OA) to scholarly outputs as demonstrated by their support of campus level OA policies translates into adoption of OA policies that apply specifically to library employees. Method: This mixed-methods study used an anonymous survey and optional open-ended interviews of scholarly communications librarians at Carnegie Classification Doctoral Universities (Very High Research [R1] and High Research [R2]) to gather information about OA policies or statements at their institutions and/or within their libraries. Results & Discussion: Variation in campus culture and governance structure meant the path from creation to adoption to implementation of a campus and/or library OA policy was similarly varied. The research reveals librarians’ motivations for and contributions to advancement of OA on their campuses, and sometimes also within their libraries. Conclusion: Many of the rationales driving adoption of campus OA policies similarly drive adoption of library-specific OA policies. Those surveyed whose institutions did have library-based OA policies referenced both the importance of leading by example and alignment with institutional mission and values.
  • Radar Backscatter and Emissivity Models of Proposed Pyroclastic Density Current Deposits on Venus

    Ganesh, I.; Carter, L.M.; Henz, T.N.; Lunar and Planetary Laboratory, University of Arizona; Department of Astronomy, University of Arizona (John Wiley and Sons Inc, 2022)
    Magellan synthetic aperture radar observations of Venus revealed a small number of deposits in the highland regions that were suggested to have formed from pyroclastic density currents. Studying these deposits is useful for understanding the nature of pyroclastic activity and eruptive history on Venus. The proposed pyroclastic deposits occupy the uppermost unit in local stratigraphy and are found near exceptionally high reflectivity ((Formula presented.) ∼0.6) units in the highlands. Their radar properties include high copolarized backscatter (∼−8 to −15 dB) and moderate emissivity values (∼0.70–0.88) in the 12.6 cm wavelength Magellan data acquired at incidence angles between ∼15° and 45°. We aim to characterize the structure of these deposits by modeling the observed backscatter and emissivity as a function of different physical and dielectric properties and shallow subsurface stratigraphy. Three different physical scenarios focusing on three different scattering mechanisms—surface scattering, subsurface scattering from buried dielectric horizons, and volume scattering from buried, distributed scatterers—are considered. By comparing the model results to Magellan observations, we narrow down likely pyroclastic deposit structures. We show that the deposits are likely analogous to dense, welded ignimbrites with high surface roughness. We also investigate other possible but less likely scenarios of a thin, low-density, low-loss mantling pyroclastic deposit on top of high reflectivity units and a thick, low-density, low-loss deposit with ∼5–10 volume % of scatterers of sub-wavelength size. Future multiwavelength, multipolarization radar observations from VERITAS and EnVision may enable unambiguous characterization of these deposits. © 2022. American Geophysical Union. All Rights Reserved.
  • Steady Long-Term Slip Rate on the Blue Cut Fault: Implications for Strain Transfer Between the San Andreas Fault and Eastern California Shear Zone

    Guns, K.A.; Bennett, R.; Blisniuk, K.; Walker, A.; Hidy, A.; Heimsath, A.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2022)
    The Eastern Transverse Ranges (ETR) province of California contains a system of E-W-trending left-lateral faults accommodating clockwise block rotation between the San Andreas Fault (SAF) system in the Coachella Valley and the Eastern California Shear Zone (ECSZ) in the Mojave Desert. Building upon established geometric relationships, we estimate that this rotation across the ETR may transfer right-lateral strain from the SAF to the ECSZ at a time-averaged rate of ∼4.3–7.7 mm/yr. Through geomorphic mapping and the analysis of 38 10Be surface exposure samples, we derive a long-term slip rate of 1.26 ± 0.50 (2σ) mm/yr over the late Pleistocene, yet analysis of the displacement record indicates a rate decrease ∼71 kya. While a rate change on this fault could have implications for possible plate boundary reorganization in this area, we argue that this slip rate variability more likely reflects routine fluctuation about a steady lifetime slip rate. © 2022. American Geophysical Union. All Rights Reserved.

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