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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Projected changes of extreme weather events in the eastern United States based on a high resolution climate modeling system

This study is the first evaluation of dynamical downscaling using the Weather Research and Forecasting (WRF) Model on a 4 km × 4 km high resolution scale in the eastern US driven by the new Community Earth System Model version 1.0 (CESM v1.0). First we examined the global and regional climate model results, and corrected an inconsistency in skin temperature during the downscaling process by modifying the land/sea mask. In comparison with observations, WRF shows statistically significant improvement over CESM in reproducing extreme weather events, with improvement for heat wave frequency estimation as high as 98%. The fossil fuel intensive scenario Representative Concentration Pathway (RCP) 8.5 was used to study a possible future mid-century climate extreme in 2057–9. Both the heat waves and the extreme precipitation in 2057–9 are more severe than the present climate in the Eastern US. The Northeastern US shows large increases in both heat wave intensity (3.05 °C higher) and annual extreme precipitation (107.3 mm more per year).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

The impacts of permafrost thaw on land-atmosphere greenhouse gas exchange

Permafrost thaw and the subsequent mobilization of carbon stored in previously frozen soil organic matter (SOM) would be a strong positive feedback to climate1. As the northern permafrost region experiences double the rate of warming as the rest of the Earth2, the vast amount of carbon in permafrost soils3 is vulnerable to thaw, decomposition and release as atmospheric greenhouse gases (GHG). Here, we employ a process-based model simulation experiment to assess the net effect of this so-called permafrost carbon feedback (PCF) in recent decades. Results show a wide-spread increase in the depth to permafrost between 1990 and 2006, with simulated active layer thickness (ALT) capturing the mean and spatial variability of the observational data. Analysis of the simulation experiment provides an estimate of a 2.8 mm/yr increase in permafrost depth, which translates to 281 TgC/yr thawed from previously frozen SOM. Overall, we estimate a net GHG forcing of 534 MtCO2eq/yr directly tied to ALT dynamics, while accounting for CO2 (562 MtCO2eq/yr) and CH4 (52 MtCO2eq/yr) release as well as CO2 uptake by vegetation (-80 MtCO2eq/yr). This net forcing represents a significant factor in the estimated 640 MtCO2eq/yr pan-arctic GHG source4, and an additional 6.9% contribution on top of the combined 7792 MtCO2eq/yr fossil fuel emissions from the eight Arctic nations over this time period5.

carbon↗
DOE OSTI2017

Global wetland contribution to 2000–2012 atmospheric methane growth rate dynamics

Increasing atmospheric methane (CH 4 ) concentrations have contributed to approximately 20% of anthropogenic climate change. Despite the importance of CH 4 as a greenhouse gas, its atmospheric growth rate and dynamics over the past two decades, which include a stabilization period (1999–2006), followed by renewed growth starting in 2007, remain poorly understood. We provide an updated estimate of CH 4 emissions from wetlands, the largest natural global CH 4 source, for 2000–2012 using an ensemble of biogeochemical models constrained with remote sensing surface inundation and inventory-based wetland area data. Between 2000–2012, boreal wetland CH 4 emissions increased by 1.2 Tg yr –1 (–0.2–3.5 Tg yr –1 ), tropical emissions decreased by 0.9 Tg yr –1 (–3.2–1.1 Tg yr –1 ), yet globally, emissions remained unchanged at 184 ± 22 Tg yr –1 . Changing air temperature was responsible for increasing high-latitude emissions whereas declines in low-latitude wetland area decreased tropical emissions; both dynamics are consistent with features of predicted centennial-scale climate change impacts on wetland CH 4 emissions. Despite uncertainties in wetland area mapping, our study shows that global wetland CH 4 emissions have not contributed significantly to the period of renewed atmospheric CH 4 growth, and is consistent with findings from studies that indicate some combination of increasing fossil fuel and agriculture-related CH 4 emissions, and a decrease in the atmospheric oxidative sink.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Informing energy consumption uncertainty: an analysis of energy data revisions

Quality energy consumption data are important for many types of analysis, and global data sets estimate trends of county level energy consumption, derived from country reported data and regional reports. We present a novel basis for informing uncertainty in energy data by quantifying the changes in reported energy consumption as countries update their previously reported data. We use 17 editions of the British Petroleum World Energy Statistics (2001-2017) to evaluate how reported energy consumption is revised over time in aggregate coal, oil, and natural gas consumption data. We find that 70% of non-zero data points are adjusted by an average of 1.3% of a country’s total fossil fuel use in the year after their first publication. Earlier data points are revised less often, but almost half of historical trends contain some revisions in later years. The size and rate of data revisions vary over countries and fuels: coal data points have larger, less frequent revisions while oil data points have smaller more frequent revisions, with natural gas in between. A K-means cluster analysis was performed to group together countries with similar revision patterns. These groups span income, economy classification, OECD membership, and regions. Standard country groupings, therefore, do not predict the extent to which a country's energy data has undergone revisions in the past.

Hoesly, Rachel M. (ORCID:0000000309652729)↗
DOE OSTI2019

Co-benefits of China’s climate policy for air quality and human health in China and transboundary regions in 2030

Abstract Climate policies targeting CO 2 emissions from fossil fuels can simultaneously reduce emissions of air pollutants and their precursors, thus mitigating air pollution and associated health impacts. Previous work has examined co-benefits of climate policy from reducing PM 2.5 in rapidly-developing countries such as China, but have not examined co-benefits from ozone and its transboundary impact for both PM 2.5 and ozone. Here, we compare the air quality and health co-benefits of China’s climate policy on both PM 2.5 and ozone in China to their co-benefits in three downwind and populous countries (South Korea, Japan and the United States) using a coupled modeling framework. In a policy scenario consistent with China’s pledge to peak CO 2 emissions in approximately 2030, avoided premature deaths from ozone reductions are 54 300 (95% confidence interval: 37 100–71 000) in China in 2030, nearly 60% of those from PM 2.5 . Total avoided premature deaths in South Korea, Japan, and the US are 1200 (900–1600), 3500 (2800–4300), and 1900 (1400–2500), respectively. Total avoided deaths in South Korea and Japan are dominated by reductions in PM 2.5 -related mortality, but ozone plays a more important role in the US. Similar to co-benefits for PM 2.5 in China, co-benefits of China’s policy for ozone and for both pollutants in those downwind countries also rise with increasing policy stringency.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Projected changes in seasonal precipitation extremes over the United States in CMIP6 simulations

Quantifying how climate change may impact precipitation extremes is a priority for informing adaptation and policy planning. In this study, Coupled Model Intercomparison Project phase 6 global climate models are analyzed to identify robust signals of projected changes in summer and winter precipitation extremes over the United States (US). Under a projected fossil-fuel based economic (i.e. high greenhouse gas emissions) scenario, our results show consistent changes in the seasonal patterns for many precipitation extremes by the end of the 21st century. We find a robust projected increase in the intensity of winter precipitation across models, with less agreement during the summer. Similarly, a robust projected amplification of heavy precipitation over the northern US is evident in winter, while intermodel spread is prevalent in summer projections. Specifically, the heavy and very heavy winter precipitation days (R10mm and R20mm) exhibit larger increases compared to other aspects of precipitation. Additionally, changes in dry extremes (e.g. consecutive dry days) are found to differ significantly across various subregions and seasons. Overall, our results suggest that the US may suffer more natural disasters such as floods and droughts in the future.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Integrated assessment model diagnostics: key indicators and model evolution

Integrated assessment models (IAMs) form a prime tool in informing climate mitigation strategies. Diagnostic indicators that allow to compare these models can help to describe and explain differences in model projections. This also increases transparency and comparability. Earlier, the IAM community has developed an approach to diagnose models (Kriegler et al., 2015). Here we build on this, by proposing a selected set of well-defined indicators as a community standard, similar to metrics used for other modeling communities such as climate models. These indicators are the relative abatement index (RAI), emission reduction type index (ERT), inertia timescale (IT), fossil fuel reduction (FFR), transformation index (TI) and cost per abatement value (CAV). We apply the approach to 17 IAMs, including both older version as well as their latest versions, as applied in the IPCC 6th Assessment Report (AR6). The study shows that the approach can be easily applied and allows for comparison of model versions in time. The indicators and their trends can often be explained in terms of model characteristics and changes. We show that together, the set of six indicators can provide an useful indication of the main traits of the model and can roughly indicate the general model behavior. The results also show that there is often a considerable spread across the models. Interestingly, the diagnostic values often change for different model versions, but there does not seem to be a distinct trend across the different models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Assessing the sequestration time scales of some ocean-based carbon dioxide reduction strategies

Abstract Ocean-based carbon dioxide (CO 2 ) removal (CDR) strategies are an important part of the portfolio of approaches needed to achieve negative greenhouse gas emissions. Many ocean-based CDR strategies rely on injecting CO 2 or organic carbon (that will eventually become CO 2 ) into the ocean interior, or enhancing the ocean’s biological pump. These approaches will not result in permanent sequestration, because ocean currents will eventually return the injected CO 2 back to the surface, where it will be brought into equilibrium with the atmosphere. Here, a model of steady state global ocean circulation and mixing is used to assess the time scales over which CO 2 injected in the ocean interior remains sequestered from the atmosphere. There will be a distribution of sequestration times for any single discharge location due to the infinite number of pathways connecting a location at depth with the sea surface. The resulting probability distribution is highly skewed with a long tail of very long transit times, making mean sequestration times much longer than typical time scales. Deeper discharge locations will sequester purposefully injected CO 2 much longer than shallower ones and median sequestration times are typically decades to centuries, and approach 1000 years in the deep North Pacific. Large differences in sequestration times occur both within and between the major ocean basins, with the Pacific and Indian basins generally having longer sequestration times than the Atlantic and Southern Oceans. Assessments made over a 50 year time horizon illustrates that most of the injected carbon will be retained for injection depths greater than 1000 m, with several geographic exceptions such as the Western North Atlantic. Ocean CDR strategies that increase upper ocean ecosystem productivity with the goal of exporting more carbon to depth will have mainly a short-term influence on atmospheric CO 2 levels because ∼70% will be transported back to the surface ocean within 50 years. The results presented here will help plan appropriate ocean CDR strategies that can help limit climate damage caused by fossil fuel CO 2 emissions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Albedo-induced global warming impact of Conservation Reserve Program grasslands converted to annual and perennial bioenergy crops

Abstract Climate benefit assessments of bioenergy crops often focus on biogeochemical impacts, paying little if any attention to biogeophysical impacts. However, land conversions required for large-scale bioenergy crop production are substantial and may directly affect the climate by altering surface energy balance. In the US, such land conversions are likely to be met in part by converting Conservation Reserve Program (CRP) grassland to bioenergy crops. Here, we converted three 22 year old CRP smooth brome grass fields into no-till corn, switchgrass, or restored prairie bioenergy crops. We assessed the biogeophysical climate impact of the conversions using albedo changes relative to unconverted reference CRP grassland. The corn and perennial fields had higher annual albedo than the grassland they replaced—causing cooling of the local climate. The cooling of the corn field occurred solely during the non-growing season—especially when surfaces were snow-covered, whereas the cooling of the perennial fields was more prominent during the growing season. Compared to biogeochemical impacts with fossil fuel offsets for the same land conversions over eight years, the annual albedo-induced climate benefits add ∼35% and ∼78% to the annual biogeochemical benefits provided from the switchgrass and restored prairie fields, respectively, and offset ∼3.3% of the annual greenhouse gas (GHG) emissions from the corn field. We conclude that albedo-induced climate mitigation from conversion of CRP lands to perennial but not annual bioenergy crops can be substantial, and future climate impact assessments of bioenergy crops should include albedo changes in addition to GHG balances in order to better inform climate policies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Future PM 2.5 emissions from metal production to meet renewable energy demand

A shift from fossil fuel to renewable energy is crucial in limiting global temperature increase to 2 °C above preindustrial levels. However, renewable energy technologies, solar photovoltaics, wind turbines, and electric vehicles are metal-intensive, and the mining and smelting processes to obtain the needed metals are emission-intensive. We estimate the future PM 2.5 emissions from mining and smelting to meet the metal demand of renewable energy technologies in two climate pathways to be 0.3–0.6 Tg yr -1 in the 2020–2050 period, which are projected to contribute 10%–30% of total anthropogenic primary PM 2.5 combustion emissions in many countries. The concentration of mineral reserves in a few regions means the impacts are also regionally concentrated. Rapid decarbonization could lead to a faster reduction of overall anthropogenic PM 2.5 emissions but also could create more unevenness in the distributions of emissions relative to where demand occurs. Options to reduce metal-related PM 2.5 emissions by over 90% exist and are well understood; introducing policy requiring their installation could avoid emission hotspots.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

2022 roadmap on 3D printing for energy

The energy transition is one of the main challenges of our society and therefore a major driver for the scientific community. To ensure a smart transition to a sustainable future energy scenario different technologies such as energy harvesting using solar cells or windmills and chemical storage in batteries, super-capacitors or hydrogen have to be developed and ultimately deployed. New fabrication approaches based on additive manufacturing and the digitalization of the industrial processes increase the potential to achieve highly efficient and smart technologies required to increase the competitiveness of clean energy technologies against fossil fuels. In this frame, the present roadmap highlights the tremendous potential of 3D printing as a new route to fully automate the manufacturing of energy devices designed as digital files. Additionally, this article gives numerous guidelines to maximize the performance and efficiency of the next generation of 3D printed devices for the energy transition while reducing the waste of critical raw materials. In particular, the paper is focused on the current status, present challenges and the expected and required advances of 3D printing for the fabrication of the most relevant energy technologies such as fuel cells and electrolysers, batteries, solar cells, super-capacitors, thermoelectric generators, chemical reactors and turbomachinery.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Techno-economic optimization of renewable urea production for sustainable agriculture and CO 2 utilization

Abstract Urea is the most used nitrogen fertilizer due to its ease of storage, transportation, and application. It is made by combining ammonia and carbon dioxide (CO 2 ), both of which are produced predominantly from fossil fuels at present. The recent momentum behind ammonia production using renewable-powered electrolysis offers an opportunity to both make urea in a more sustainable way and utilize CO 2 from external sources. In this work, we present a techno-economic optimization model to minimize the cost of making urea in this way. The model allows for time-varying chemical production in response to renewable variability by simultaneously optimizing production facility design and hourly operation. We performed a case study for Minnesota considering the use of byproduct CO 2 from bioethanol production. We found that the present-day levelized cost of renewable urea is between $268 mt −1 and $413 mt −1 at likely implementable production scales up to 250 000 mt yr −1 . This is within the range of historical conventional urea prices while offering at least 78% carbon intensity reduction. Projecting to 2030, there is a clear economic case for renewable urea production with levelized cost as low as $135 mt −1 due to technology improvement and electrolysis manufacturing expansion, facilitating a urea production scale increase to 525 000 mt yr −1 . Optimal facilities use wind energy, with hydrogen and ammonia production operating in a flexible, time-varying way to minimize battery and hydrogen storage capacities. Urea production operates near steady state due to the relatively low cost of intermediate ammonia buffer storage. A mix of imported methane and locally produced hydrogen are used to provide heat for steam consumed in the urea synthesis.

Chemistry↗
DOE OSTI2022

Improving future travel demand projections: a pathway with an open science interdisciplinary approach

Transport accounts for 24% of global CO 2 emissions from fossil fuels. Governments face challenges in developing feasible and equitable mitigation strategies to reduce energy consumption and manage the transition to low-carbon transport systems. To meet the local and global transport emission reduction targets, policymakers need more realistic/sophisticated future projections of transport demand to better understand the speed and depth of the actions required to mitigate greenhouse gas emissions. In this paper, we argue that the lack of access to high-quality data on the current and historical travel demand and interdisciplinary research hinders transport planning and sustainable transitions toward low-carbon transport futures. We call for a greater interdisciplinary collaboration agenda across open data, data science, behaviour modelling, and policy analysis. These advancemets can reduce some of the major uncertainties and contribute to evidence-based solutions toward improving the sustainability performance of future transport systems. The paper also points to some needed efforts and directions to provide robust insights to policymakers. We provide examples of how these efforts could benefit from the International Transport Energy Modeling Open Data project and open science interdisciplinary collaborations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Supplementing biofuel mandates with a carbon mitigation policy can lead to water quality co-benefits

Biofuel mandates can impact the environment in multiple ways that may be positive or negative, including affecting life-cycle greenhouse gas (GHG) emissions by displacing fossil fuels, affecting soil carbon stocks due to accompanying land use change, and water quality due to changes in fertilizer requirements and the mix of crops used as feedstocks. To achieve desired environmental outcomes in the presence of a biofuel mandate, additional policy instruments must be adopted to supplement the mandate. We develop an integrated and spatially explicit ecosystem-economic modeling framework to analyze the cost-effectiveness of alternative policies to achieve desired targets for GHG emissions reduction from the agricultural and fuel sectors in the USA and nitrate leaching reduction in the Gulf of Mexico below the levels that would be achieved by a corn ethanol and/or a cellulosic ethanol mandate in the USA. We find that while a corn ethanol mandate lowers GHG emissions, it increases nitrate leaching due to the expansion of corn production; a cellulosic ethanol mandate lowers both GHG emissions and nitrate leaching relative to a corn ethanol mandate, but the additional carbon and nitrate prices are needed to achieve anticipated GHG reduction and nitrate reduction targets. We also find that accompanying a biofuel mandate with a GHG reduction target alone leads to substantial nitrate reduction co-benefits, but a nitrate reduction target alone is less effective in reducing GHG emissions. Combining a GHG standard with a nitrate standard can achieve GHG and nitrate reduction targets at lower carbon and nitrate prices as compared to implementing each of these policies independently. Furthermore, our findings show that disregarding policy co-benefits can overestimate the GHG and nitrate prices needed to achieve policy targets and higher policy costs.

09 BIOMASS FUELS↗
DOE OSTI2022

A Biomass Pyrolysis Oil as a Novel Insect Growth Regulator Mimic for a Variety of Stored Product Beetles

Abstract As fumigants face increasing regulatory restrictions, resistance, and consumer pushback, it is vital to expand the integrated pest management (IPM) chemical toolkit for stored products. The production of biomass derived insecticides (e.g., bio-oil fraction) from byproducts of biofuel production may be a promising alternative source of chemistries for controlling stored product insects. These potential insecticidal bio-oils were fractionated based on boiling points (ranging from 115 to 230°C in one series and 245–250°C in another). Fractions were analyzed using GC-MS, and were found to be unique in composition. The lethality of these fractions was tested on Tribolium castaneum, Tribolium confusum, and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Fractions were tested at concentrations ranging from 5–260 mg/ml to screen for efficacy against adults for durations of 2–8 hr sprayed on concrete arenas. In addition, a separate assay evaluated adult emergence of larvae after 6 wk with supplemental food in arenas, while repellency was evaluated against four stored product insect species in a laminar wind tunnel. A greenhouse gas (GHG) emissions life cycle assessment was also performed, which found the use of the bio-oil fraction could reduce GHG emissions associated with the insecticide supply chain by 25–61% relative to a fossil-fuel based insecticide or pyrethroid. While adults were largely unaffected, we found that larval emergence was significantly suppressed compared to controls by roughly half or more. We also determined that there was minimal repellency to most fractions by most species. We conclude that the use of bio-oil fractions is a climate-friendly choice that may support IPM programs.

09 BIOMASS FUELS↗
DOE OSTI2024

A pilot oral history of plant synthetic biology

The whole field of synthetic biology (SynBio) is only about 20 years old, and plant SynBio is younger still. Nevertheless, within that short time, SynBio in general has drawn more scientific, philosophical, government, and private-sector interest than anything in biology since the recombinant DNA revolution. Plant SynBio, in particular, is now drawing more and more interest in relation to plants’ potential to help solve planetary problems such as carbon capture and storage and replacing fossil fuels and feedstocks. As plant SynBio is so young and so fast-developing, we felt it was too soon to try to analyze its history. Instead, we set out to capture the essence of plant SynBio's origins and early development through interviews with 8 of the field's founders, representing 5 countries and 3 continents. We then distilled these founders’ personal recollections and reflections into this review, centering the narrative on timelines for pivotal events, articles, funding programs, and quoting from interviews. We have archived the interview recordings and documented timeline entries. This work provides a resource for future historical scholarship.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

In-Situ Metabolomic Analysis of Setaria viridis Roots Colonized by Beneficial Endophytic Bacteria

Over the past decades, crop yields have risen in parallel with increasing use of fossil-fuel derived nitrogen (N) fertilizers, but with concomitant negative impacts on climate and water resources. There is a need for more sustainable agricultural practices, and biological nitrogen fixation (BNF) could be part of the solution. A variety of nitrogen-fixing, epiphytic and endophytic plant growth promoting bacteria (PGPB) are known to stimulate plant growth. However, compared to the rhizobium-legume symbiosis, little mechanistic information is available as to how PGPB affect plant metabolism. Therefore, we investigated the metabolic changes in roots of the model grass species Setaria viridis upon endophytic colonization by Herbaspirillum seropedicae SmR1 (fix + ) or a fix - mutant strain (SmR54), compared to uninoculated roots. Endophytic colonization of the root is highly localized and, hence, analysis of whole root segments dilutes the metabolic signature of those few cells impacted by the bacteria. Therefore, we utilized in situ laser ablation electrospray ionization mass spectrometry (LAESI-MS) to sample only those root segments at or adjacent to the sites of bacterial colonization. We report netabolites involved in purine, zeatin, and riboflavin pathways were significantly more abundant in inoculated plants while metabolites indicative of nitrogen, starch, and sucrose metabolism were reduced in roots inoculated with the fix - strain or uninoculated, presumably due to N limitation. Interestingly, compounds, involved in indole-alkaloid biosynthesis were more abundant in the roots colonized by the fix - strain, perhaps reflecting a plant defense response.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Functional characterization of three GH10 xylanases

Decreased availability of fossil fuels has driven an increased demand for sustainable energy sources such as biofuels. One area of bioenergy research involves development of biocatalysts able to efficiently degrade biomass “waste”‐products, such as substrates derived from corn stover, rather than easily‐fermentable biomass used for food, such as starch from corn kernels. Xylanases are of interest for their ability to hydrolyze hemicellulosic sugars found in plant cell walls, allowing utilization of waste‐derived biomass. In this study, three xylanases of glycoside hydrolase family 10 (GH10) are functionally characterized and optimized for temperature and pH, as well as kinetically analyzed for xylose monomer and oligomer production. These enzymes, GH10‐4, GH10‐9, and GH10‐15, demonstrate activity upon substrates xylan and arabinoxylan. For GH10‐4, optima are 50°C at pH 8 on xylan and 45°C at pH 8 on arabinoxylan. For GH10‐9, optima are 70°C at pH 5 on xylan and 70°C at pH 5 on arabinoxylan. For GH10‐15, optima are 50°C at pH 8 on xylan and 45°C at pH 5 on arabinoxylan. Kinetic analysis reveals GH10‐4 produces xylose (X1), xylobiose (X2), xylotriose (X3), xylotetraose (X4), and xylopentaose (X5) from xylan, while GH10‐9 and GH10‐15 produce X1, X2, and X3. From arabinoxylan, GH10‐4 produces X1, X2, X3, X4, while GH10‐9 and GH10‐15 produce X1, X2, X3. Conclusive kinetic data may suggest applicability of these enzymes for industrial use within biocatalysts and contribute further insight to the functionality of enzymes within GH10. Support or Funding Information The authors are grateful for financial support by the Integrated Biological Sciences Summer Research Program (IBS‐SRP, NSF) at the University of Wisconsin‐Madison and the Great Lakes Bioenergy Research Center (GLBRC) of the U.S. Department of Energy. Presentation travel support is provided by the Ronald E. McNair Scholars Program of Winthrop University. The authors also thank Lai Bergeman, Craig Bingman, Bob Smith, Emily Beebe, Kirk Vander Meulen, Amber Smith, David Wassarman, and John Greenler for professional support.

Park, Jesslyn↗