Now showing items 1-20 of 16268

    • 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.
    • Mesozoic Tectonic Evolution in the Kurgovat-Vanch Complex, NW Pamir

      Li, Y.; Robinson, A.C.; Zucali, M.; Gadoev, M.; Oimuhammadzoda, I.; Lapen, T.J.; Carrapa, B.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2022)
      Different crustal deformation histories between Tibet and the Pamir reflect along-strike variations in geodynamics of the Tethys orogen. To investigate the less well-documented deformation history of the Pamir, which has been a barrier in understanding the nature of these differences, we conducted an integrated study in the Kurgovat-Vanch region, NW Pamir. The lithologies are primarily Ediacaran-to-Carboniferous metasedimentary rocks intruded by Carboniferous plutons, which then experienced Late Triassic to Early Jurassic regional metamorphism. Structural mapping and analyses document a low-angle NW-directed thrust fault, the Poshkharv thrust, separating the overlying upper-greenschist facies Poshkharv complex from the underlying amphibolite facies Kurgovat complex. Regional geologic maps indicate the Poshkharv thrust continues for ∼300 km across the NW Pamir. Our study also documents another regional thrust fault, the top-to-the-SE Vanch thrust that juxtaposes the Southern Kurgovat complex above the lower-grade Vanch complex in the south. Biotite 40Ar/39Ar thermochronology indicates Early Cretaceous movement on all structures with ∼135–125 Ma exhumation along the NW-directed Poshkharv thrust and ∼125–115 Ma exhumation along the SE-directed Vanch thrust. Regional crustal deformation in the Northern Pamir was formed in a Cretaceous retro-arc setting, unrelated to the Cenozoic India-Asia collision. Cretaceous deformation in the NW Pamir was broadly coeval with the NE Pamir, but preceded Cretaceous shortening and coeval arc magmatism in the Southern Pamir. We interpret Early Cretaceous thrusting and crustal thickening followed by southward migration of shortening and magmatic flare-up in the Pamir to have resulted from a transition of Neotethys subduction from northward flat-slab advancing to southward retreating. © 2022. American Geophysical Union. All Rights Reserved.
    • When and Where Are Multiple Snow Layers Important for Simulations of Snow Accumulation and Melt?

      Cristea, N.C.; Bennett, A.; Nijssen, B.; Lundquist, J.D.; Hydrology & Atmospheric Sciences, University of Arizona (John Wiley and Sons Inc, 2022)
      Many watershed-scale and land surface models incorporate snowmelt modules with simplified representations of the snowpack with three or fewer layers. These modeling choices were traditionally made to reduce model complexity and computational demand while still being able to simulate large model domains. However, these simple snow layering schemes may not always simulate snow processes and the effects of climate change across a range of climatic and geographic conditions. Here we evaluate simple snow layering schemes (having two to five layers, commonly found in watershed-scale and land surface models) against a synthetic benchmark with up to 100 layers at three locations with different climate conditions using the SUMMA modeling framework. We evaluate 10 different layering configurations of two to five layers with variable thicknesses and show that the effect of the layering scheme varies with site conditions. We find that the layer configuration is more important at a cold high elevation site in the Sierra Nevada, California (∼1.4°C annual average temperature), and at a warm site in the French Alps (∼6.5°C), and less important at a site in Idaho (∼5.0°C). The top layer thickness of the simpler snow layering configurations also influences the simulated snow surface and snowpack temperatures and timing of snowmelt. Our tests showed that the five-layer model with thin layers near the surface was closest to the benchmark (median NSE = 0.99), and therefore we recommend using multiple snow layers for reliable simulations of snow accumulation and melt across a range of climates. © 2022. American Geophysical Union. All Rights Reserved.
    • Impact of Meteorological Factors on the Mesoscale Morphology of Cloud Streets during a Cold-Air Outbreak over the Western North Atlantic

      Chen, J.; Wang, H.; Li, X.; Painemal, D.; Sorooshian, A.; Thornhill, K.L.; Robinson, C.; Shingler, T.; Department of Chemical and Environmental Engineering, University of Arizona (American Meteorological Society, 2022)
      Postfrontal clouds (PFC) are ubiquitous in the marine boundary layer, and their morphology is essential to estimating the radiation budget in weather and climate models. Here we examine the roles of sea surface temperature (SST) and meteorological factors in controlling the mesoscale morphology and evolution of shallow clouds associated with a cold-air outbreak that occurred on 1 March 2020 during phase I of the Aerosol Cloud Meteorology Interactions over the Western Atlantic Experiment (ACTIVATE). Our results show that the simulated PFC structure and ambient conditions by the Weather Research and Forecasting (WRF) Model are generally consistent with observations from GOES-16 and dropsonde measurements. We also examine the thermodynamical and dynamical influences in the cloud mesoscale morphology using WRF sensitivity experiments driven by two meteorological forcing datasets with different domain-mean SST and spatial gradients, which lead to dissimilar values of hydrometeor water path and cloud core fraction. The SST from ERA5 leads to weaker stability and higher inversion height than the SST from FNL does. In addition, the use of large-scale meteorological forcings from ERA5 yields a distinctive time evolution of wind direction shear in the inner domain, which favors the formation and persistence of longer cloud rolls. Both factors contribute to a change in the time evolution of domain-mean water path and cloud core fraction of cloud streets. Our study takes advantage of the simulation driven by the differences between two large-scale forcing datasets to illustrate the importance of SST and wind direction shear in the cloud street morphology in a realistic scenario. © 2022 American Meteorological Society.
    • Advances in Subseasonal to Seasonal Prediction Relevant to Water Management in the Western United States

      Sengupta, A.; Singh, B.; DeFlorio, M.J.; Raymond, C.; Robertson, A.W.; Zeng, X.; Waliser, D.E.; Jones, J.; Department of Hydrology and Atmospheric Sciences, University of Arizona (American Meteorological Society, 2022)
      Virtual Workshop on Subseasonal to Seasonal Climate Forecasting for Water Management in the Western U.S. What: Scientists and stakeholders came together to discuss forecast priorities for western U.S. water resource management and to review existing and emerging methodologies that can improve prediction of precipitation, circulation regimes, and atmospheric rivers at lead times of weeks to months. When: 15–17 March 2022 Where: Online, hosted by IRI, Columbia Climate School ©2022 American Meteorological Society.
    • Static polarizabilities within the generalized Kohn-Sham semicanonical projected random phase approximation (GKS-spRPA)

      Balasubramani, S.G.; Voora, V.K.; Furche, F.; Department of Chemistry and Biochemistry, University of Arizona (American Institute of Physics Inc., 2022)
      An analytical implementation of static dipole polarizabilities within the generalized Kohn-Sham semicanonical projected random phase approximation (GKS-spRPA) method for spin-restricted closed-shell and spin-unrestricted open-shell references is presented. General second-order analytical derivatives of the GKS-spRPA energy functional are derived using a Lagrangian approach. By resolution-of-the-identity and complex frequency integration methods, an asymptotic O(N4â ilog(N)) scaling of operation count and O(N3) scaling of storage is realized, i.e., the computational requirements are comparable to those for GKS-spRPA ground state energies. GKS-spRPA polarizabilities are assessed for small molecules, conjugated long-chain hydrocarbons, metallocenes, and metal clusters, by comparison against Hartree-Fock (HF), semilocal density functional approximations (DFAs), second-order Møller-Plesset perturbation theory, range-separated hybrids, and experimental data. For conjugated polydiacetylene and polybutatriene oligomers, GKS-spRPA effectively addresses the "overpolarization"problem of semilocal DFAs and the somewhat erratic behavior of post-PBE RPA polarizabilities without empirical adjustments. The ensemble averaged GKS-spRPA polarizabilities of sodium clusters (Nan for n = 2, 3, ..., 10) exhibit a mean absolute deviation comparable to PBE with significantly fewer outliers than HF. In conclusion, analytical second-order derivatives of GKS-spRPA energies provide a computationally viable and consistent approach to molecular polarizabilities, including systems prohibitive for other methods due to their size and/or electronic structure. © 2022 Author(s).
    • Loomisite, Ba[Be2P2O8]•H2O, the first natural example with the zeolite ABW-type framework, from Keystone, Pennington County, South Dakota, USA

      Yang, H.; Gu, X.; Gibbs, R.B.; Downs, R.T.; Department of Geosciences, University of Arizona (Cambridge University Press, 2022)
      A new beryllophosphate mineral species, loomisite (IMA 2022-003), ideally Ba[Be2P2O8]•H2O, was found from the Big Chief mine near Keystone, Pennington County, South Dakota, USA. It occurs as divergent sprays of very thin bladed crystals with a tapered termination. Individual crystals are found up to 0.80 x 0.06 x 0.03 mm. Associated minerals include dondoellite, earlshannonite, mitridatite, rockbridgeite, jahnsite-(CaMnFe), and quartz. No twinning or parting is observed macroscopically. Loomisite is murky white in transmitted light, transparent with white streak and silky to vitreous luster. It is brittle and has a Mohs hardness of 3½-4, with perfect cleavage on (100) and (-110). The measured and calculated densities are 3.46(5) and 3.512 g/cm3, respectively. Optically, loomisite is biaxial (+), with α = 1.579(5), β = 1.591(5), γ = 1.606(5) (white light), 2V (meas.) = 82(2)º, 2V (calc.) = 85º. It is non-pleochroic under polarized light, with a very weak (r > v) dispersion. The mineral is insoluble in water or hydrochloric acid. An electron microprobe analysis, along with the BeO content measured with an ICP-MS, yields an empirical formula (based on 9 O apfu) (Ba0.96Ca0.06)Ʃ1.02[(Be1.96Fe0.06)Ʃ2.02P1.99O8]•H2O, which can be simplified to (Ba,Ca)[(Be,Fe)2P2O8]•H2O. Loomisite is monoclinic, with space group Pn and unit-cell parameters a = 7.6292(18), b = 9.429(2), c = 4.7621(11) Å, β = 91.272(5)◦, V= 342.47(14) Å3, and Z = 2. Its crystal structure is characterized by a framework of corner-sharing PO4 and BeO4 tetrahedra. The framework can be considered as built from the stacking of sheets consisting of 4- and 8-membered rings (4.82 nets) along [001] or hexagonal layers (63 nets) along [010]. The extra-framework Ba2+ and H2O are situated in the channels formed by the 8-membered rings. Topologically, loomisite represents the first natural example with the zeolite ABW-type framework, which is adopted by over 100 synthetic compounds with different chemical compositions. © 2022 Cambridge University Press. All rights reserved.
    • CAD-RADS™ 2.0 – 2022 Coronary Artery Disease – Reporting and Data System An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR) and the North America Society of Cardiovascular Imaging (NASCI)

      Cury, R.C.; Leipsic, J.; Abbara, S.; Achenbach, S.; Berman, D.; Bittencourt, M.; Budoff, M.; Chinnaiyan, K.; Choi, A.D.; Ghoshhajra, B.; et al. (Radiological Society of North America Inc., 2022)
      Coronary Artery Disease Reporting and Data System (CAD-RADS) was created to standardize reporting system for patients undergoing coronary CT angiography (CCTA) and to guide possible next steps in patient management. The goal of this updated 2022 CAD-RADS 2.0 is to improve the initial reporting system for CCTA by considering new technical developments in Cardiac CT, including data from recent clinical trials and new clinical guidelines. The updated CAD-RADS classification will follow an established framework of stenosis, plaque burden, and modifiers, which will include assessment of lesion-specific ischemia using CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), when performed. Similar to the method used in the original CAD-RADS version, the determinant for stenosis severity classification will be the most severe coronary artery luminal stenosis on a per-patient basis, ranging from CAD-RADS 0 (zero) for absence of any plaque or stenosis to CAD-RADS 5 indicating the presence of at least one totally oc-cluded coronary artery. Given the increasing data supporting the prognostic relevance of coronary plaque burden, this document will provide various methods to estimate and report total plaque burden. The addition of P1 to P4 descriptors are used to denote increasing categories of plaque burden. The main goal of CAD-RADS, which should always be interpreted together with the impression found in the report, remains to facilitate communication of test results with referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will continue to provide a framework of standardization that may benefit education, research, peer-review, artificial intelligence development, clinical trial design, population health and quality assurance with the ultimate goal of improving patient care. © 2022 Society of Cardiovascular Computed Tomography.
    • GOES ABI Detection of Thin Cirrus over Land

      McHardy, T.M.; Campbell, J.R.; Peterson, D.A.; Lolli, S.; Garnier, A.; Kuciauskas, A.P.; Surratt, M.L.; Marquis, J.W.; Miller, S.D.; Dolinar, E.K.; et al. (American Meteorological Society, 2022)
      This study develops a new thin cirrus detection algorithm applicable to overland scenes. The methodology builds from a previously developed overwater algorithm, which makes use of the Geostationary Operational Environmental Satellite 16 (GOES-16) Advanced Baseline Imager (ABI) channel 4 radiance (1.378-μm “cirrus” band). Calibration of this algorithm is based on coincident Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) cloud profiles. Emphasis is placed on rejection of false detections that are more common in overland scenes. Clear-sky false alarm rates over land are examined as a function of precipitable water vapor (PWV), showing that nearly all pixels having a PWV of <0.4 cm produce false alarms. Enforcing an above-cloud PWV minimum threshold of ∼1 cm ensures that most low-/midlevel clouds are not misclassified as cirrus by the algorithm. Pixel-filtering based on the total column PWV and the PWV for a layer between the top of the atmosphere (TOA) and a predetermined altitude H removes significant land surface and low-/midlevel cloud false alarms from the overall sample while preserving over 80% of valid cirrus pixels. Additionally, the use of an aggressive PWV layer threshold preferentially removes noncirrus pixels such that the remaining sample is composed of nearly 70% cirrus pixels, at the cost of a much-reduced overall sample size. This study shows that lower-tropospheric clouds are a much more significant source of uncertainty in cirrus detection than the land surface. © 2022 American Meteorological Society.
    • Embossed sheet glass lens arrays for hybrid PV modules

      Angel, R.; Eads, R.; Hartweg, B.; Holman, Z.; Didato, N.; Steward Observatory Solar Lab, University of Arizona (American Institute of Physics Inc., 2022)
      In hybrid PV-CPV modules the glass entrance window of a silicon module is replaced by an array of lenses that concentrate direct sunlight onto very small but twice-as-efficient multijunction PV cells while transmitting indirect daylight to the silicon. Hybrid modules have the potential for conversion efficiciency nearly double that of conventional silicon PV modules, and could become a major source of utility scale solar electricity generation. But for commercial success the added costs of the lens array, small CPV cells and dual rather than single axis tracking must be kept low. Here we describe a method for forming large lens arrays directly from glass as part of large-scale float glass manufacturing. A wide, continuous sheet of newly formed and still soft glass is embossed like shower glass, by passage between two rollers. These imprint cylindrical lenses on the upper and lower surfaces, arrayed at right angles to each other. The lenses act together to form point foci, where the multijunction cells are located on the silicon cells. The cost of lens arrays mass-produced in this way should be little more than that of the flat glass sheets of conventional modules, which in many cases are already roll-formed with textured surfaces to reduce reflection. We describe experiments made with commercially available embossed glass and cylindrical lenses. © 2022 Author(s).
    • Aircraft Observations of Turbulence in Cloudy and Cloud-Free Boundary Layers Over the Western North Atlantic Ocean From ACTIVATE and Implications for the Earth System Model Evaluation and Development

      Brunke, M.A.; Cutler, L.; Urzua, R.D.; Corral, A.F.; Crosbie, E.; Hair, J.; Hostetler, C.; Kirschler, S.; Larson, V.; Li, X.-Y.; et al. (John Wiley and Sons Inc, 2022)
      This study examines boundary layer turbulence derived from high temporal resolution meteorological measurements from 40 research flights over the western North Atlantic Ocean during the 2020 deployments of ACTIVATE. Frequency distributions of various turbulent quantities reveal stronger turbulence during the winter deployment than in summer and for cloud-topped than in cloud-free boundary layers during the summer deployment. Maximum turbulence kinetic energy (TKE) is most often within cloud from observations in winter and summer, whereas it is mostly below cloud in both seasons by a global model turbulence parameterization. Bivariate frequency distributions are consistent with the bivariate Gaussian probability distribution functions assumed for the closure of higher-order turbulence/shallow convection parameterizations used by some global models. Turbulence simulated by the Community Atmosphere Model version 6 and the Energy Exascale Earth System Model Atmosphere Model version 2 using such parameterizations is not as strong as observed, with more TKE going into vertical wind perturbations rather than into zonal wind perturbations as observed, suggesting that the treatment of turbulence in Earth system models still needs to be further improved. © 2022. American Geophysical Union. All Rights Reserved.
    • Martian Ionospheric Magnetic Fluctuations Below 200 km

      Esman, T.M.; Espley, J.; Gruesbeck, J.; Fowler, C.M.; Xu, S.; Elrod, M.; Harada, Y.; Giacalone, J.; Lunar and Planetary Laboratory, University of Arizona (John Wiley and Sons Inc, 2022)
      We conduct a search for 5–16 Hz magnetic waves below 200 km and within the Martian ionosphere using data from multiple instruments onboard the Mars Atmosphere and Volatile EvolutioN mission spacecraft. We present a case study and an analysis of the 54 identified events to establish trends. Nearly half the wave events occur near the cusps of strong crustal magnetic fields (CMFs). The stronger regions have fewer events and may be a result of stronger CMFs preventing draped field lines from reaching lower altitudes. A majority of the observed magnetic waves occur on the nightside, are associated with greater fluxes of electrons traveling downward along the local magnetic field compared to those traveling upward, and correspond to increases in thermal plasma density. These aspects indicate electron precipitation was present during these wave events. We conclude that the waves are observed under magnetic field conditions favorable for the penetration of electrons and waves into the lower ionosphere, but that the electron precipitation cannot solely account for the waves or plasma changes. © 2022. American Geophysical Union. All Rights Reserved.
    • What does the processing of chunks by learners of Chinese tell us? An acceptability judgment investigation

      Lu, X.; Wang, J.; Department of East Asian Studies, University of Arizona (Walter de Gruyter GmbH, 2022)
      Chunks are multi-word sequences that constitute an important component of the mental lexicon. In second language (L2) acquisition, chunking is essential for attaining fluency and idiomaticity. In the present study, in order to examine whether chunks provide a processing advantage over non-chunks for L2 learners at different levels of proficiency, three groups (beginner, intermediate, and advanced) English-speaking learners of Chinese participated in an online acceptability judgment task and a familiarity rating task. Our results revealed that the participants in all three groups processed chunks faster and with fewer errors than they did non-chunks. It was also found that the observed processing advantage of chunks could not be explained by a familiarity effect alone, thus suggesting that L2 learners across the board store chunks as holistic units. The implications of chunk instruction in relation to input frequency and variability in L2 settings are also discussed. © 2022 Walter de Gruyter GmbH, Berlin/Boston 2022.
    • On the Relevance of Aerosols to Snow Cover Variability Over High Mountain Asia

      Roychoudhury, C.; He, C.; Kumar, R.; McKinnon, J.M.; Arellano, A.F., Jr.; Department of Hydrology and Atmospheric Sciences, University of Arizona (John Wiley and Sons Inc, 2022)
      While meteorology and aerosols are identified as key drivers of snow cover (SC) variability in High Mountain Asia, complex non-linear interactions between them are not adequately quantified. Here, we attempt to unravel these interactions through a simple relative importance (RI) analysis of meteorological and aerosol variables from ERA5/CAMS-EAC4 reanalysis against satellite-derived SC from Moderate Resolution Imaging Spectroradiometer across 2003–2018. Our results show a statistically significant 7% rise in the RI of aerosol-meteorology interactions (AMI) in modulating SC during late snowmelt season (June and July), notably over low snow-covered (LSC) regions. Sensitivity tests further reveal that the importance of meteorological interactions with individual aerosol species are more prominent than total aerosols over LSC regions. We find that the RI of AMI for LSC regions is clearly dominated by carbonaceous aerosols, on top of the expected importance of dynamic meteorology. These findings clearly highlight the need to consider AMI in hydrometeorological monitoring, modeling, and reanalyses. © 2022. American Geophysical Union. All Rights Reserved.
    • The Unprecedented Character of California's 20th Century Enhanced Hydroclimatic Variability in a 600-Year Context

      Zamora-Reyes, D.; Broadman, E.; Bigio, E.; Black, B.; Meko, D.; Woodhouse, C.A.; Trouet, V.; Department of Hydrology and Atmospheric Sciences; Laboratory of Tree-Ring Research, University of Arizona (John Wiley and Sons Inc, 2022)
      Recently, year-to-year swings in California winter precipitation extremes have resulted in drought, wildfires, and floods causing billions of dollars in damage. These recent precipitation swings represent an increasing trend in variability of California's hydroclimate over the past decades. Here, we put this trend in a longer-term context using tree-ring-based precipitation, streamflow, and snow water equivalent reconstructions. We show that the statewide rise in hydroclimate variability in the 20th century is driven by an increasing trend in the magnitude of wet extremes. A prior period of strong variability in the 16th century, in contrast, is related to an increasing trend in the magnitude of dry extremes. Our results are consistent with climate model simulations that suggest an increasingly volatile future for California's hydroclimate and highlight the importance of collaboration between scientists and water resource managers to incorporate this increased variability into their decision-making and planning, acknowledging higher risks for compound events. © 2022. American Geophysical Union. All Rights Reserved.
    • Laser-induced dynamic alignment of the HD molecule without the Born-Oppenheimer approximation

      Adamowicz, L.; Kvaal, S.; Lasser, C.; Pedersen, T.B.; Department of Chemistry and Biochemistry, University of Arizona (American Institute of Physics Inc., 2022)
      Laser-induced molecular alignment is well understood within the framework of the Born-Oppenheimer (BO) approximation. Without the BO approximation, however, the concept of molecular structure is lost, making it hard to precisely define alignment. In this work, we demonstrate the emergence of alignment from the first-ever non-BO quantum dynamics simulations, using the HD molecule exposed to ultrashort laser pulses as a few-body test case. We extract the degree of alignment from the non-BO wave function by means of an operator expressed in terms of pseudo-proton coordinates that mimics the BO-based definition of alignment. The only essential approximation, in addition to the semiclassical electric-dipole approximation for the matter-field interaction, is the choice of time-independent explicitly correlated Gaussian basis functions. We use a variational, electric-field-dependent basis-set construction procedure, which allows us to keep the basis-set dimension low while capturing the main effects of electric polarization on the nuclear and electronic degrees of freedom. The basis-set construction procedure is validated by comparing with virtually exact grid-based simulations for two one-dimensional model systems: laser-driven electron dynamics in a soft attractive Coulomb potential and nuclear rovibrational dynamics in a Morse potential. © 2022 Author(s).
    • Integrating Model-Based Systems and Digital Engineering for Crewed Mars Mission Planning

      Kirshner, Mitchell; Valerdi, Ricardo; University of Arizona (American Institute of Aeronautics and Astronautics (AIAA), 2022-10)
      With technological advances in the 21st century and the rise of the commercial space industry, crewed Mars missions to land humans on our red neighbor have become increasingly feasible. One of the key challenges in accomplishing this goal is determining whether model-based systems engineering training is necessary for space systems engineers to adopt digital engineering. This paper reviews model-based systems engineering benefits and limitations, as well as historically significant crewed Mars missions that planned to land on the surface. Models are presented for a Mars transit habitat developed in the modeling language SysML using Cameo Systems Modeler. These models leverage Cameo’s simulation capabilities to execute MATLAB scripts integrating digital engineering software Systems Tool Kit into the modeling process, demonstrating a reusable interoperability methodology for Mars mission planning not yet existing in this domain’s literature. It can be concluded that integrating model-based systems engineering with digital engineering for crewed Mars landing mission planning can lead to multiple benefits for space systems digital engineering, including 1) greater system simulation capabilities, 2) enhanced model fidelity, and 3) improved system understanding. Future research to further enhance these benefits includes adding cybersecurity considerations and greater system detail to the models.
    • Ghana digitised its address system: Its failure offers lessons to other African countries creating smart cities

      Frimpong, Louis Kusi; Abunyewah, Matthew; Okyere, Seth Asare; Diko, Stephen Kofi; University of Arizona (The Conversation US, Inc., 2022-11-22)