Now showing items 11448-11467 of 11675

    • Warm jupiters in tess full-frame images: A catalog and observed eccentricity distribution for year 1

      Dong, J.; Huang, C.X.; Dawson, R.I.; Foreman-Mackey, D.; Collins, K.A.; Quinn, S.N.; Lissauer, J.J.; Beatty, T.; Quarles, B.; Sha, L.; et al. (American Astronomical Society, 2021)
      Warm Jupiters-defined here as planets larger than 6 Earth radii with orbital periods of 8-200 days-are a key missing piece in our understanding of how planetary systems form and evolve. It is currently debated whether Warm Jupiters form in situ, undergo disk or high-eccentricity tidal migration, or have a mixture of origin channels. These different classes of origin channels lead to different expectations for Warm Jupiters' properties, which are currently difficult to evaluate due to the small sample size. We take advantage of the Transiting Exoplanet Survey Satellite (TESS) survey and systematically search for Warm Jupiter candidates around main-sequence host stars brighter than the TESS-band magnitude of 12 in the full-frame images in Year 1 of the TESS Prime Mission data. We introduce a catalog of 55 Warm Jupiter candidates, including 19 candidates that were not originally released as TESS objects of interest by the TESS team. We fit their TESS light curves, characterize their eccentricities and transit-timing variations, and prioritize a list for ground-based follow-up and TESS Extended Mission observations. Using hierarchical Bayesian modeling, we find the preliminary eccentricity distributions of our Warm-Jupiter-candidate catalog using a beta distribution, a Rayleigh distribution, and a two-component Gaussian distribution as the functional forms of the eccentricity distribution. Additional follow-up observations will be required to clean the sample of false positives for a full statistical study, derive the orbital solutions to break the eccentricity degeneracy, and provide mass measurements. © 2021. The American Astronomical Society.
    • A Warm Layer in the Nightside Mesosphere of Mars

      Nakagawa, Hiromu; Jain, Sonal K.; Schneider, Nicholas M.; Montmessin, Franck; Yelle, Roger V.; Jiang, Fayu; Verdier, Loic; Kuroda, Takeshi; Yoshida, Nao; Fujiwara, Hitoshi; et al. (AMER GEOPHYSICAL UNION, 2020-02-17)
      We report a new set of stellar occultation measurements for nightside temperature profiles made by the Mars Atmosphere and Volatile EvolutioN/Imaging Ultraviolet Spectrograph that provide evidence for a recurring layer of warm air between 70 and 90 km altitudes in the nightside mesosphere of Mars during L-s = 0-180 degrees in Martian Year 33-34. The nightside profiles reveal a recurring peak of atmospheric temperature around 80 km over the equator to the middle latitudes in the northern hemisphere. The predictions of the Mars Climate Database have a warm layer with much smaller amplitudes. The observed peak amplitudes are larger than those predicted by the model by up to 90 K. Wavenumber-3 structures are seen in the warm layer that are potentially signatures of thermal tides or stationary planetary waves, with amplitudes two times larger than predicted.
    • Warming and precipitation addition interact to affect plant spring phenology in alpine meadows on the central Qinghai-Tibetan Plateau

      Ganjurjav, Hasbagan; Gornish, Elise S.; Hu, Guozheng; Schwartz, Mark W.; Wan, Yunfan; Li, Yue; Gao, Qingzhu; Univ Arizona, Sch Nat Resources & Environm (ELSEVIER, 2020-06-15)
      Temperature and precipitation are primary regulators of plant phenology. However, our knowledge of how these factors might interact to affect plant phenology is incomplete. The Qinghai-Tibetan Plateau, a cold and high region, has experienced no consistent changes in spring phenology, despite a significant warming trend. We conducted a manipulative experiment of warming and precipitation addition in an alpine meadow on the Qinghai-Tibetan Plateau in 2015 (cold and wet), 2016 (warm and dry) and 2017 (mild and very wet). We found that warming increased annual variability of plant spring phenology. Warming delayed green up of all monitored species in 2016, advanced green up of early flowering species in 2015, and did not alter green up in 2017. For example, green up of the shallow rooted Kobresia pygmaea advanced 8 (+/- 2) days in 2015 and was delayed by 23 (+/- 3) days in a dry year (2016) under warming compared with control. Early spring precipitation addition can offset the delaying effects of warming in a dry year on the Qinghai-Tibetan Plateau. Under warming plus precipitation addition, community average green up advanced compared to control plots in 2015 and 2016, and community average flowering advanced for all three years. In 2016, flowering of K. pygmaea (an early flowering species) advanced under warming plus precipitation addition compared to control while flowering of other species did not change. Our results highlight that annual variation of soil moisture condition plays a critical role in determining the magnitude and direction of spring phenology response to warming. We provide insights in how plant spring phenology might change in a warmer future in the presence or absence of precipitation increase.
    • Warming‐induced shrubline advance stalled by moisture limitation on the Tibetan Plateau

      Wang, Yafeng; Liang, Eryuan; Lu, Xiaoming; Camarero, J. Julio; Babst, Flurin; Shen, Miaogen; Peñuelas, Josep; School of Natural Resources and the Environment, University of Arizona; University of Arizona (Wiley, 2021-09-22)
      Willows (Salix) are some of the most abundant shrubs in cold alpine and tundra biomes. In alpine regions, seed dispersal is not limiting upwards willow expansion, so the upslope shift of willow shrublines is assumed to be a response to climatic warming. Very little, however, is known about the recent spatiotemporal dynamics of alpine willow shrublines. The world's highest willow shrublines (ca 4900 m a.s.l.) are located on the Tibetan Plateau (TP) and provide a rare opportunity to test their sensitivity and responses to rapid warming and the associated increase in the demand for water in ecosystems. We used a new data set comprising 24 Salix shrubline plots along a 900-km latitudinal gradient (30‒38°N) to reconstruct the rates of annual shrub recruitment and shifting shrubline positions since 1939. Shrub densification and shrubline advances were promoted by pronounced summer warming before 2010, contributing to widespread greening on the TP. These trends, however, reversed due to warming-induced moisture limitation after 2010, which thus represented a tipping point of warming/drying trade-offs. Climatic warming and drying are predicted to accelerate in the following decades, so alpine plant communities may be at an increasing risk of population decline or even range contraction.
    • Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

      Secrest, Nathan J.; Schmitt, Henrique R.; Blecha, Laura; Rothberg, B.; Fischer, Jacqueline; Univ Arizona, LBT Observ (IOP PUBLISHING LTD, 2017-02-17)
      We present a combined morphological and X-ray analysis of Was. 49, an isolated, dual-AGN system notable for the presence of a dominant AGN, Was 49b, in the disk of the primary galaxy, Was 49a, at a projected radial distance of 8. kpc from the nucleus. Using X-ray data from Chandra, the Nuclear Spectroscopic Telescope Array, and Swift, we find that this AGN has a bolometric luminosity of L-bol similar to 10(45) erg s(-1), with a black hole mass of M-BH = 1.3(-0.9)(+10)M(circle dot) . Despite the large mass, our analysis of optical data from the Discovery Channel Telescope shows that the supermassive black hole (SMBH) is hosted by a stellar counterpart with a mass of only 5.6(-2.6)(+4.9)M(circle dot), which makes the SMBH potentially larger than expected from SMBH-galaxy scaling relations, and the stellar counterpart exhibits a morphology that is consistent with dwarf elliptical galaxies. Our analysis of the system in the r and K bands indicates that Was. 49 is a minor merger, with the mass ratio of Was 49b to Was 49a between similar to 1:7 and similar to 1:15. This is in contrast with findings that the most luminous merger-triggered AGNs are found in major mergers and that minor mergers predominantly enhance AGN activity in the primary galaxy.
    • Was Aztec and Mixtec turquoise mined in the American Southwest?

      Thibodeau, Alyson M.; López Luján, Leonardo; Killick, David J.; Berdan, Frances F.; Ruiz, Joaquin; Univ Arizona, Sch Anthropol; Univ Arizona, Dept Geosci (AMER ASSOC ADVANCEMENT SCIENCE, 2018-06)
      Archaeologists have long suggested that prehispanic states in Mesoamerica acquired turquoise through long-distance exchange with groups living in what is now the American Southwest and adjacent parts of northern Mexico. To test this hypothesis, we use lead and strontium isotopic ratios to investigate the geologic provenance of 43 Mesoamerican turquoise artifacts, including 38 mosaic tiles from offerings within the Sacred Precinct of Tenochtitlan (the Mexica or Aztec capital) and 5 tiles associated with Mixteca-style mosaics currently held by the Smithsonian's National Museum of the American Indian. Most of these artifacts have isotopic signatures that differ from turquoise deposits in the American Southwest, but closely match copper deposits and crustal rocks in Mesoamerica. We thus conclude that turquoise used by the Aztecs and Mixtecs likely derives from Mesoamerican sources and was not acquired through long-distance exchange with the Southwest.
    • Was Gale Crater (Mars) Connected to a Regionally Extensive Groundwater System?

      Roseborough, V.; Horvath, D.G.; Palucis, M.C.; Lunar & Planetary Laboratory, University of Arizona (Blackwell Publishing Ltd, 2021)
      Gale crater, home of the Curiosity rover, contains some of the best geomorphic and sedimentologic evidence on Mars for large lakes during the Hesperian and Amazonian. Orbital data and rover observations of delta deposits and terminations of gully networks suggest several phases of stable lake levels. However, the regional extent, water source (groundwater vs. surface water), and climate during each lake stand are debated. Consistent gully network termination elevations (GNTEs) within Gale and 17 regional craters suggest that GNTEs record paleolake levels. Hydrologic modeling indicates these lakes may have been coeval and the result of a regional groundwater table, recording a drying trend from subhumid conditions to semiarid conditions. Crater counting indicates that most lake-hosting craters impacted after ∼3.7 Ga and surface water persisted intermittently until the Early Amazonian, constraining the timing but not duration of lakes. This work has implications for understanding water sources and volumes affecting sediments investigated by Curiosity. © 2021. American Geophysical Union. All Rights Reserved.
    • WASP-52b. The effect of starspot correction on atmospheric retrievals

      Bruno, Giovanni; Lewis, Nikole K; Alam, Munazza K; López-Morales, Mercedes; Barstow, Joanna K; Wakeford, Hannah R; Sing, David; Henry, Gregory W; Ballester, Gilda E; Bourrier, Vincent; et al. (OXFORD UNIV PRESS, 2019-11-18)
      We perform atmospheric retrievals on the full optical to infrared (0.3-5 mu m) transmission spectrum of the inflated hot Jupiter WASP-52b by combining HST/STIS, WFC3 IR, and Spitzer/IRAC observations. As WASP-52 is an active star that shows both out-of-transit photometric variability and star-spot crossings during transits, we account for the contribution of non-occulted active regions in the retrieval. We recover a 0.1-10x solar atmospheric composition, in agreement with core accretion predictions for giant planets, and no significant contribution of aerosols. We also obtain a <3000K temperature for the star-spots, a measure which is likely affected by the models used to fit instrumental effects in the transits, and a 5 per cent star-spot fractional coverage, compatible with expectations for the host star's spectral type. Such constraints on the planetary atmosphere and on the activity of its host star will inform future JWST GTO observations of this target.
    • Wastewater surveillance for sars-cov-2 on college campuses: Initial efforts, lessons learned and research needs

      Harris-Lovett, S.; Nelson, K.L.; Beamer, P.; Bischel, H.N.; Bivins, A.; Bruder, A.; Butler, C.; Camenisch, T.D.; De Long, S.K.; Karthikeyan, S.; et al. (MDPI AG, 2021)
      Wastewater surveillance for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging approach to help identify the risk of a coronavirus disease (COVID-19) out-break. This tool can contribute to public health surveillance at both community (wastewater treatment system) and institutional (e.g., colleges, prisons, and nursing homes) scales. This paper ex-plores the successes, challenges, and lessons learned from initial wastewater surveillance efforts at colleges and university systems to inform future research, development and implementation. We present the experiences of 25 college and university systems in the United States that monitored campus wastewater for SARS-CoV-2 during the fall 2020 academic period. We describe the broad range of approaches, findings, resources, and impacts from these initial efforts. These institutions range in size, social and political geographies, and include both public and private institutions. Our analysis suggests that wastewater monitoring at colleges requires consideration of local information needs, sewage infrastructure, resources for sampling and analysis, college and community dynam-ics, approaches to interpretation and communication of results, and follow-up actions. Most colleges reported that a learning process of experimentation, evaluation, and adaptation was key to progress. This process requires ongoing collaboration among diverse stakeholders including decision-mak-ers, researchers, faculty, facilities staff, students, and community members. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • Water and carbon dioxide distribution in the 67P/Churyumov-Gerasimenko coma from VIRTIS-M infrared observations

      Migliorini, A.; Piccioni, G.; Capaccioni, F.; Filacchione, G.; Bockelée-Morvan, D.; Erard, S.; Leyrat, C.; Combi, M. R.; Fougere, N.; Crovisier, J.; et al. (EDP SCIENCES S A, 2016-04-12)
      Context. Studying the coma environment of comet 67P/Churyumov-Gerasimenko (67P) is one of the primary scientific goals of the VIRTIS experiment on the ESA Rosetta mission. Aims. The distribution and variability of water vapour and carbon dioxide in the comet's coma are needed to estimate their production rate, abundances in the nucleus, and the spatial distribution of the active regions. Methods. Infrared emission lines from vibrational bands of water and carbon dioxide at 2.67 and 4.27 mu m, respectively, were observed by the VIRTIS-M imaging channel and mapped from close to the nucleus up to similar to 10 km altitude with a resolution of similar to 40 m/px. A dataset consisting of 74 observations in the 1 5 mu m spectral range acquired from 8 to 14 April 2015 when 67P was at a heliocentric distance of 1.9 AU is analysed in this work. A statistical correlation between the gas distribution and the surface's active regions was performed. Results. The maximum H2O emission is observed within 3 km from the nucleus and is mainly concentrated above two active regions, Aten-Babi and Seth-Hapi, while the CO2 distribution appears more uniform with significant emissions coming from both the "head" and southern latitude regions. In the equatorial region, the column densities of both species decrease with altitude, although CO2 decreases more rapidly than H2O. The calculated CO2/H2O column density ratios above Aten-Babi and Seth-Hapi are 2.4 +/- 0.6% and 3.0 +/- 0.7%, respectively. A value equal to 3.9 +/- 1.0% is observed at equatorial latitudes in the region encompassing Imothep. Conclusions. VIRTIS-M has mapped the distribution of water vapour and carbon dioxide around the nucleus of 67P with unprecedented spatial resolution. The different water and carbon dioxide outgassing above the surface, seen in the VIRTIS-M data, might be indicative of a different thermal history of the northern and southern hemispheres of 67P.
    • Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

      Sori, Michael M.; Bramson, Ali M.; Univ Arizona, Lunar & Planetary Lab (AMER GEOPHYSICAL UNION, 2019-02-12)
      Recent analysis of radar data from the Mars Express spacecraft has interpreted bright subsurface radar reflections as indicators of local liquid water at the base of the south polar layered deposits (SPLD). However, the physical and geological conditions required to produce melting at this location were not quantified. Here we use thermophysical models to constrain parameters necessary to generate liquid water beneath the SPLD. We show that no concentration of salt is sufficient to melt ice at the base of the SPLD in the present day under typical Martian conditions. Instead, a local enhancement in the geothermal heat flux of >72 mW/m(2) is required, even under the most favorable compositional considerations. This heat flow is most simply achieved via the presence of a subsurface magma chamber emplaced 100 s of kyr ago. Thus, if the liquid water interpretation of the observations is correct, magmatism on Mars may have been active extremely recently.
    • Water Production Rates and Activity of Interstellar Comet 2I/Borisov

      Xing, Zexi; Bodewits, Dennis; Noonan, John; Bannister, Michele T.; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2020-04-27)
      We observed the interstellar comet 2I/Borisov using the Neil Gehrels Swift Observatory's Ultraviolet/Optical Telescope. We obtained images of the OH gas and dust surrounding the nucleus at six epochs spaced before and after perihelion (-2.56 to 2.54 au). Water production rates increased steadily before perihelion from (7.0 1.5) x 10(26) molecules s(-1) on 2019 November 1, to (10.7 1.2) x 10(26) molecules s(-1) on December 1. This rate of increase in water production rate is quicker than that of most dynamically new comets and at the slower end of the wide range of Jupiter-family comets. After perihelion, the water production rate decreased to (4.9 0.9) x 10(26) molecules s(-1) on December 21, which is much more rapidly than that of all previously observed comets. Our sublimation model constrains the minimum radius of the nucleus to 0.37 km, and indicates an active fraction of at least 55% of the surface. A(0)f rho calculations show a variation between 57.5 and 105.6 cm with a slight trend peaking before the perihelion, lower than previous and concurrent published values. The observations confirm that 2I/Borisov is carbon-chain depleted and enriched in NH2 relative to water.
    • Water splitting activity of oxygen-containing groups in graphene oxide catalyst in bipolar membranes

      Martínez, Rodrigo J.; Farrell, James; Univ Arizona, Dept Chem & Environm Engn (ELSEVIER, 2019-09-15)
      Graphene oxide (GO) is a very effective catalyst for splitting water into H+ and OH− ions in bipolar membranes. This research investigated the catalytic activity of six oxygenated functional groups in GO for water splitting. Møller-Plesset second order perturbation method (MP2) simulations were performed to calculate activation barriers for proton acceptance and release reactions with and without an applied electric field. The relative catalytic activity for the functional groups on GO was independent of the electric field intensity and dielectric constant. The catalytic activity for accepting and releasing a proton linearly correlated with the pKa of the functional groups. The edge carboxylate site had the highest catalytic activity for water splitting, and had activation barriers that were 0.2 to 0.4 kcal/mol higher than a model tertiary amine. This suggests that the high catalytic activity of GO results from a high catalytic site density, as opposed to a chemical effect.
    • Water splitting promoted by electronically conducting interlayer material in bipolar membranes

      Chen, Yingying; Martínez, Rodrigo J.; Gervasio, Don; Baygents, James C.; Farrell, James; Univ Arizona, Dept Chem & Environm Engn (SPRINGER, 2019-11-06)
      Bipolar membranes are used in a variety of industrial applications to split water into hydronium and hydroxide ions. This research investigated the hypothesis that an electronically conducting material between the anion and cation exchange membranes can increase the rate of water splitting by increasing the electric field intensity in the mobile ion depleted region. Bipolar membranes were constructed with electronically conducting (graphene and carbon nanotubes) and electronically insulating (graphene oxide) interlayer materials of varying thickness. All three interlayer materials decreased the voltage required for water splitting compared to a bipolar membrane with no interlayer material. Quantum chemistry simulations were used to determine the catalytic effect of proton accepting and proton releasing sites on the three interlayer materials. Neither graphene nor carbon nanotubes had catalytic sites for water splitting. Thicker layers of graphene oxide resulted in decreased rates of water splitting at each applied potential. This effect can be attributed to a diminished electric field in the mobile ion depleted region with increasing catalyst layer thickness. In contrast, membrane performance with the electronically conducting graphene and carbon nanotube interlayers was independent of the interlayer thickness. An electrostatic model was used to show that interlayer electronic conductance can increase the electric field intensity in the mobile ion depleted region as compared to an electronically insulating material. Thus, including electronically conducting material in addition to a traditional catalyst may be a viable strategy for improving the performance of bipolar membranes.
    • Water storage and release policies for all large reservoirs of conterminous United States

      Turner, Sean W.D.; Steyaert, Jennie Clarice; Condon, Laura; Voisin, Nathalie; University of Arizona (Elsevier BV, 2021-12)
      Large-scale hydrological and water resource models (LHMs) require water storage and release schemes to represent flow regulation by reservoirs. Owing to a lack of observed reservoir operations, state-of-the-art LHMs deploy a generic reservoir scheme that may fail to represent local operating behaviors. Here we introduce a new dataset of bespoke water storage and release policies for 1,930 reservoirs of conterminous United States. The Inferred Storage Targets and Release Functions (ISTARF-CONUS) dataset relies on a new inventory of observed daily reservoir operations (ResOpsUS) to generate reservoir operating rules for 595 data-rich reservoirs. These functions are developed in a standardized form that allows for extrapolation of operating schemes to 1,335 data-scarce reservoirs—leading to the first inventory of empirically derived reservoir operating policies for all large CONUS reservoirs documented in the Global Reservoir and Dams (GRanD) database. Evaluation of the new scheme in daily simulations forced with observed inflow demonstrates substantial and robust improvement for both release and storage relative to the popular Hanasaki method. Performance of the extrapolation approach for data-scarce reservoirs is evaluated with leave-one-out validation and is shown to also offer modest gains on average over Hanasaki. ISTARF-CONUS may be readily adopted in any LHM featuring large reservoirs of the conterminous United States.
    • Water Supply and Ancient Society in the Lake Balkhash Basin: Runoff Variability along the Historical Silk Road

      Panyushkina, Irina P.; Macklin, Mark G.; Toonen, Willem H. J.; Meko, David M.; University of Arizona, Laboratory of Tree-Ring Research (SPRINGER, 2019-02-28)
      Expansion of agricultural practices from the Fertile Crescent to China during the mid and late Holocene are believed to have shaped the early network of Silk Road routes and possibly regulated the dynamics of trade and exchange in the urban oases along the Silk Road throughout its existence. While the impacts of climate change on the Silk Road are more or less documented for the medieval period, they remain poorly understood for early history of the Silk Road, especially in Central Asia. We analyze hydroclimatic proxies derived from fluvial stratigraphy, geochronology, and tree-ring records that acted on various time scales in the Lake Balkhash Basin to learn how changes in water supply could have influenced the early farmers in the Semirechye region of southern Kazakhstan. Our approach aims to identify short-term and long-term variability of regional runoff and to compare the hydrological data with cultural dynamics coupled with the archaeological settlement pattern and agricultural production. The reconstructed runoff variability underscore the contribution of winter precipitation driven by the interaction between the Arctic oscillation and the Siberian High-Pressure System, to Central Asian river discharge. We show that Saka people of the Iron Age employed extensive ravine agriculture on the alluvial fans of the Tian Shan piedmont, where floodwater farming peaked between 400 BC and 200 BC. The early Silk Road farmers on the alluvial fans favored periods of reduced flood flows, river stability and glacier retreat in the Tian Shan Mountains. Moreover, they were able to apply simple flow control structures to lead water across the fan surface. It is very unlikely that changes in water supply ever significantly constricted agricultural expansion in this region.
    • Water, Law, and Development in Chile/California Cooperation, 1960–70s

      Bauer, Carl; Catalán, Luis; University of Arizona (PERGAMON-ELSEVIER SCIENCE LTD, 2017-02)
      During 1963-78 the governments and the top universities of Chile and California undertook three programs of binational development assistance and cooperation. The programs built on a long historical relationship between the two regions, marked by their striking similarities in physical geography and natural resources, despite being 1,000s of miles apart on opposite sides of the Equator. The first program was for technical development assistance to Chile in the framework of the Alliance for Progress, and involved the three governments of Chile, California, and the United States. Water resources and river basin development planning were a primary emphasis, and led to building Chile's largest dual-purpose reservoir (Colbun). The second program was for graduate-level academic exchange and involved the two leading public university systems, the University of Chile and the University of California. This comprehensive program was funded for more than a decade by the Ford Foundation, with agriculture, natural sciences, and engineering the dominant fields. The third program was a separate effort to reform Chilean legal education, led by Stanford Law School and funded by the Ford Foundation. This Chile Law Program was a leading international example of the "law and development" movement in the 1960s, which overlapped closely with the early years of the "law and society" movement in the U.S. Both university and law school programs ended after the Chilean military coup in 1973. What were the impacts of these programs on water, law, and society in both Chile and California? What lessons can we learn today from those historical experiences? We answer these questions with an historical overview and synthesis of diverse documents and evidence. In focusing on water, law, and society, we aim to contribute to the interdisciplinary synthesis of different fields of development studies.
    • The Water-Energy-Food Nexus: A systematic review of methods for nexus assessment

      Albrecht, Tamee R; Crootof, Arica; Scott, Christopher A; Univ Arizona, Sch Geog & Dev (IOP Publishing, 2018-04)
      The water-energy-food (WEF) nexus is rapidly expanding in scholarly literature and policy settings as a novel way to address complex resource and development challenges. The nexus approach aims to identify tradeoffs and synergies of water, energy, and food systems, internalize social and environmental impacts, and guide development of cross-sectoral policies. However, while the WEF nexus offers a promising conceptual approach, the use of WEF nexus methods to systematically evaluate water, energy, and food interlinkages or support development of socially and politically-relevant resource policies has been limited. This paper reviews WEF nexus methods to provide a knowledge base of existing approaches and promote further development of analytical methods that align with nexus thinking. The systematic review of 245 journal articles and book chapters reveals that (a) use of specific and reproducible methods for nexus assessment is uncommon (less than one-third); (b) nexus methods frequently fall short of capturing interactions among water, energy, and food—the very linkages they conceptually purport to address; (c) assessments strongly favor quantitative approaches (nearly three-quarters); (d) use of social science methods is limited (approximately one-quarter); and (e) many nexus methods are confined to disciplinary silos—only about one-quarter combine methods from diverse disciplines and less than one-fifth utilize both quantitative and qualitative approaches. To help overcome these limitations, we derive four key features of nexus analytical tools and methods—innovation, context, collaboration, and implementation—from the literature that reflect WEF nexus thinking. By evaluating existing nexus analytical approaches based on these features, we highlight 18 studies that demonstrate promising advances to guide future research. This paper finds that to address complex resource and development challenges, mixed-methods and transdisciplinary approaches are needed that incorporate social and political dimensions of water, energy, and food; utilize multiple and interdisciplinary approaches; and engage stakeholders and decision-makers.
    • Water-Womb-Land Cosmologic: Protocols for Traditional Ecological Knowledge

      Gonzales, Patrisia; Univ Arizona, Dept Mexican Amer Studies, Grad Interdisciplinary Program Amer Indian Studies; Univ Arizona, Native Amer Res & Training Ctr (Mary Ann Liebert Inc, 2020-06-01)
      As the granddaughter of Kickapoo, Comanche, and Macehual peoples who migrated throughout the present-day United States and Mexico, I am most concerned with what happens as our traditional ecological knowledge changes when it is taken out of the spaces and relationships over time that we have developed with our lands, our waters, our medicines. I raise questions regarding cultural appropriation and the consequences that emerge when Indigenous knowledge becomes generalizable knowledge. Some of the key questions explored in this article include the following: What relationships surround the knowledge of the Original Peoples? Why is it that when traditional knowledge is taken out of its original relations newcomers learn the plant knowledge and then ask, "What money can I make from this knowledge?" How can we factor in the realities of colonization that result in the original peoples of a place becoming disconnected from traditional knowledge? To situate this discussion, I explore water knowledge from my perspective as a traditional birth attendant and traditional herbalist and an Indigenous scholar who teaches courses on Indigenous medicine. I discuss how the one signifier of water can have multiple existences, meanings, and forms. In contrast to deep knowledge that has been carried across time by Indigenous peoples, I call into question knowledge that is based on profit rather than on seeking a deep relationship with the environment that allows balanced relationships with the natural world-and the knowledge that those relationships create-to continue. Discussion also focuses on some key values and recommended protocols for traditional knowledge exchange, including (a) Acknowledgement, (b) Accountability, (c) Accessibility and Affordability, (d) Relatedness, and (e) Reciprocity.
    • A wave-bending structure at Ka-band using 3D-printed metamaterial

      Wu, Junqiang; Liang, Min; Xin, Hao; Univ Arizona, Dept Elect & Comp Engn (AMER INST PHYSICS, 2018-03-30)
      Three-dimensional printing technologies enable metamaterials of complex structures with arbitrary inhomogeneity. In this work, a 90 degrees wave-bending structure at the Ka-band (26.5-40 GHz) based on 3D-printed metamaterials is designed, fabricated, and measured. The wave-bending effect is realized through a spatial distribution of varied effective dielectric constants. Based on the effective medium theory, different effective dielectric constants are accomplished by special, 3D-printable unit cells, which allow different ratios of dielectric to air at the unit cell level. In contrast to traditional, metallic-structure-included metamaterial designs, the reported wave-bending structure here is all dielectric and implemented by the polymer-jetting technique, which features rapid, low-cost, and convenient prototyping. Both simulation and experiment results demonstrate the effectiveness of the wave-bending structure.