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A Framework to Integrate Microclimate Conditions in Building Energy Use Models at a Whole-City Scale
No full textUrbanization and climate change have intensified the need for advanced methods to simulate building energy performance within realistic urban environmental contexts. This study presents a microclimate-informed framework for developing representative building energy prototypes that enable the estimation of energy use for buildings sharing similar microclimatic conditions and building-level characteristics. The framework is demonstrated using Des Moines, Iowa, as a case study. The framework combines high-resolution microclimate modeling with geospatial analysis to quantify the influence of urban form and vegetation on building energy use. Localized weather files were generated using the Weather Research and Forecasting (WRF) model to capture spatial variations in microclimate across the city. Detailed three-dimensional models of buildings and trees were developed from Light Detection and Ranging (LiDAR) point cloud data and integrated with building attributes, including construction materials and heating and cooling systems, to generate representative building typologies use them to build a similarity-based lookup table. Urban energy simulations were conducted using the Urban Modeling Interface (UMI). To demonstrate the effectiveness of the framework, simulations were conducted for two building prototypes according to the framework. Results show that monthly energy use intensity (EUI) of a representative cluster compared to randomly selected buildings differs by 10% to 19%, with both positive and negative deviations observed depending on building template and month. Thus, the proposed framework shows great promise to capture comparable energy performance trends across buildings with similar construction characteristics and urban context and minimize computational demands for doing so. While evapotranspiration effects are not explicitly modeled in the current framework, they are recognized as an important microclimatic process and will be incorporated in future work. This study demonstrates that the proposed framework provides a scalable and computationally efficient approach for urban-scale energy analysis and can support data driven decision making for climate-responsive urban planning.This article is published as Lawrence, S.; Passe, U.; Thompson, J. A Framework to Integrate Microclimate Conditions in Building Energy Use Models at a Whole-City Scale. Climate 2026, 14, 42. https://doi.org/10.3390/cli14020042.Funding
The authors acknowledge support from the US NSF under Grant # 1855902. Any opinions, findings, and conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF
Antimicrobial resistance in the environment: transport, transfer, and evolution
No full textThe release of manure and wastewater into soil and water provides a pathway for the dissemination of antimicrobial resistance (AMR) in the environment. This dissertation describes three research projects investigating the transport, transfer, and evolution of antimicrobial resistance in environmental contexts. The first two projects examine interactions between manured field runoff and edge-of-field conservation practices, specifically prairie strips. The third investigates the evolution of AMR under low antimicrobial pressures, aiming to understand better the dynamics of AMR development within wastewater treatment plants.
The first study questioned whether antimicrobial resistance genes (ARGs) from manured field surface runoff are vertically transported through prairie strip soil profiles. Prairie strips are narrow plantings of native prairie and perennial vegetation placed within or along the edges of crop fields. They intercept field runoff and have been shown to decrease ARG abundances in manured field runoff to pre-manure levels, while causing minimal increases in ARGs in surface soils, suggesting that they may instead be moving through soil profiles. Prairie strip soil columns were exposed to simulated field runoff derived from swine manure, anaerobically digested swine manure, or a mineral solution. ARGs were detected at depths of at least 53 cm in soil. ARGs were also detectable in leachate, though most appeared to be retained or degraded within the soil. These results demonstrate that prairie strips effectively capture and attenuate ARGs from manured field runoff and provide the first evidence of deep ARG movement within prairie strip soils.
The second study questioned whether prairie strip root endophytes become more resistant to erythromycin after exposure to manured field runoff. Manured field runoff moving vertically through prairie strip soils would expose plant root microbiomes to AMR contaminants. The effect of this exposure on the antimicrobial resistance of plant root endophytes is unknown. To explore this topic, root endophytes were extracted from the existing prairie strip soil columns described in the prior project. Results showed that, although total resistant endophyte abundance did not consistently increase following manure exposure, variability in resistance among isolates did increase. The abundance of resistant isolates in anaerobically digested manure–exposed roots closely tracked with the increases in Pseudomonas abundances. This finding may suggest a link between the abundance of Pseudomonas and the dynamics of resistance. The results of this project indicate that exposure to manure runoff can alter root endophyte resistance phenotypes without increasing the relative abundance of resistant bacteria.
The third study investigated how E. coli cultures exposed to low concentrations of azithromycin develop resistance to high concentrations of the same antibiotic. This question is relevant to the study of AMR evolution within wastewater treatment plants, which collect and process human waste in an environment containing diverse bacteria communities and low concentrations of multiple types of antimicrobial compounds, including antibiotics. Previous research has shown that exposure to low concentrations of antibiotics can promote the development of resistance or tolerance to higher antimicrobial concentrations. However, little is known about the process of this evolution. Escherichia coli populations were cultured in media containing azithromycin at one-quarter of the ancestral culture’s minimum inhibitory concentration (MIC). After 700 generations, azithromycin-exposed populations exhibited clearly increased MICs. Resistance phenotype variation among evolved isolates indicated the presence of multiple resistant lineages within the cultures. Whole-genome sequencing found variations in genes associated with biofilm formation and efflux or transport systems in cultures exposed to azithromycin. These findings indicate that low-level antibiotic exposure is associated with the occurrence of diverse AMR phenotypes, which may be linked to nonspecific resistance mechanisms.
Together, these three projects illustrate how AMR is transported, retained, or amplified in environments affected by human and animal waste. As global populations grow and animal production intensifies, waste will continue to carry AMR far from its point of origin. This dissertation adds to the body of knowledge regarding AMR transport, transfer, and evolution in the environment
Large increases in maize residue carbon inputs in the US Corn Belt from 1980 to 2020
No full textMaize residue, the remaining biomass after crop harvest, represents the largest soil carbon input in agricultural lands. Residue affects crop yields and sustainability through its impact on soil carbon-nutrient-water processes. Here, we address the lack of spatial and temporal knowledge by synthesizing field experiments with public surveys to estimate maize residue quantity and quality at the county level in the US Corn Belt. We found that maize residue carbon input has increased by 46% from 1980 to 2020, with today’s gross production worth $14.3 billion in carbon markets. The increase was caused by increased maize productivity (77%) and area expansion (23%). While more residue production is desirable for soil carbon sequestration, large residue amounts challenge the implementation of conservation practices such as low-intensity tillage and cover crops. The historical increase in maize residue amount is large and variable across the landscape. Our study provides actionable data for re-assessing residue management practices to optimize productivity and sustainability, especially in high-yielding areas.This article is published as Ruiz, A., Castellano, M.J., Ferela, A. et al. Large increases in maize residue carbon inputs in the US Corn Belt from 1980 to 2020. Commun Earth Environ 7, 60 (2026). https://doi.org/10.1038/s43247-025-03078-3This study was supported by FFAR (project title: Evaluating the relative influence of maize breeding, field management, and environmental setting on crop production and sustainability targets), Bayer Crop Science, Leopold Center for Sustainable Development, the Plant Science Institute of Iowa State University, the Fulbright Program, and the Argentina Ministry of Education
Can Native Vegetation in Agroecosystems Provide a Net Benefit for Pollinators, Despite Pesticide Use?
No full textPollinator health and population declines are of global concern, with ramifications for biodiversity conservation and the human food supply. Although the establishment of native flowering vegetation is a broadly supported pollinator conservation strategy, concerns about enhancing habitat in agroecosystems with widespread pesticide use remain. To evaluate this trade-off, we synthesized research findings for prairie strips, a model conservation practice that involves patches of diverse, native plants within row-crop fields. Prairie strips enhance pollinator forage quantity and quality, support a more diverse and abundant wild bee community, sustain monarch butterflies, and increase managed honey bee productivity. Although exposure to pesticides may occur, concentrations are typically below levels that have negative impacts on pollinator health. We discuss knowledge gaps and conclude native vegetation enhancements in agricultural landscapes, including those with widespread pesticide use, are a promising strategy for pollinator conservation, with the potential for net positive effects despite pesticide exposure.This article is published as Amy L Toth, Adam G Dolezal, Ashley L St. Clair, Edward M Hsieh, Maura J Hall, Kate E Borchardt, Matthew D Stephenson, Steven P Bradbury, John C Tyndall, Matthew E O’Neal, Lisa A Schulte, Can Native Vegetation in Agroecosystems Provide a Net Benefit for Pollinators, Despite Pesticide Use?, BioScience, 2026;, biaf194, https://doi.org/10.1093/biosci/biaf194This work and several cited studies by the authors were supported by the following grants: United States Department of Agriculture (USDA)-National Institute of Food and Agriculture (NIFA) grant no. 2017–68004-26326 to ALT, AGD, and MEO; USDA-FSA grants no. AG-3151-C-0041, no. AG-3151-P-14–0065, and no. AG-3151-P-14–0162 to LASM; USDA-NIFA grant no. 2015–67019-23002 to LASM; Iowa Soybean Association grant no. Y8CWNJRCNN91 to AGD, MEO, LASM, and ALT; and grant no. 549025 from the Foundation for Food and Agricultural Research to LASM, ALT, AGD, MEO, and JCT. The aforementioned FFAR grant involved matching funds from Bayer Crop Science, DuPont Pioneer (now Corteva Agriscience), the College of Agriculture and Life Science at Iowa State University and the Graduate Program in Sustainable Agriculture, and Syngenta; these funders were not involved in determining or executing the scope of work
Effect of cross-fostering piglets on within litter transmission of porcine reproductive and respiratory syndrome virus under field conditions
No full textObjective: This field study aimed to evaluate the effect of cross-fostering on the porcine reproductive and respiratory syndrome virus (PRRSV) transmission within litters.Materials and methods: A breed-to-wean farm was selected 15 weeks after a PRRSV outbreak with a L1C.5 strain. Litters included in the study had all piglets individually identified and sampled. Litters were classified as positive when at least one piglet tested positive (PRRSV-2 RNA by quantitative reverse transcriptase-polymerase chain reaction). Cross-fostering was carried out within 48 hours after birth to establish five study groups: one positive piglet moved to a negative litter (n = 15), one negative piglet moved to a positive litter (n = 3), one negative piglet moved to a negative litter (n = 13), and two control groups without cross-fostering (positive litters, n = 5; negative litters, n = 14). All piglets were resampled prior to weaning. The increase in new PRRSV-positive piglets within litters was compared across study groups. Results: Compared to negative litters without cross-fostering, there was no difference in the increase of new PRRSV-positive piglets for groups where negative piglets were moved to either negative or positive litters or the group where a positive piglet was introduced into a negative litter. However, positive litters that did not receive any piglets had a significantly higher count of new PRRSV-positive piglets. Implication: Under the conditions of this study, cross-fostering did not influence the increase in new cases of PRRSV-positive piglets.This article is published as De Conti, Elisa, Kristen Cleaver, Onyekachukwu H. Osemeke, Claire LeFevre, Ching-Yang Wang, Mariamawit Z. Mohammed, Laura Solis Avila et al. "Effect of cross-fostering piglets on within-litter transmission of porcine reproductive and respiratory syndrome virus under field conditions." (2026). doi: https://doi.org/10.54846/jshap/1435.This study was supported by Boehringer Ingelheim Grants 2024
A multi-disciplinary approach to characterize genes that contribute to maize fatty acid elongation and cuticular wax biosynthesis
No full textFatty acids represent essential molecular building blocks of lipids that contribute to structural, metabolic, and signaling processes across all domains of life. This thesis focuses on very-long-chain fatty acids (VLCFAs) that consist of acyl-chains with 20 or more carbon atoms. VLCFAs are produced by the fatty acid elongase (FAE) system, which is a four step, cyclical pathway that elongates a preexisting acyl-CoA by two carbons with every turn of the FAE cycle. The maize FAE system (ZmFAE) is replete with genetic redundancy, specifically in the 3-ketoacyl-CoA synthase (ZmKCS) enzyme family that catalyzes the initial Claisen condensation step, as 28 sequences that are hypothesized to encode a ZmKCS have been identified in the maize genome. To understand the genetic redundancy of the maize system, we generated Saccharomyces cerevisiae strains that express unique iterations of the ZmFAE pathway in the absence of the endogenous yeast FAE (ScFAE) enzymes. This approach demonstrated that the entire ScFAE system could be complemented by ZmFAE enzymes and represents the first constructed strains that express a homogenous plant-based FAE. We established that 14 unique iterations of the ZmFAE system could complement the endogenous ScFAE enzymes, and in doing so established the product profiles of each ZmFAE isozyme. We also developed dual-ZmKCSs strains to begin to address the complexity of the ZmFAE system that is present in planta, as many plant tissues express different combinations of ZmKCS isozymes.
In plants, VLCFAs (in the form of VLCFA-CoAs) serve as the precursors to the waxes that are incorporated into the cuticle, which is a hydrophobic barrier that protects the plant against environmental stresses, including drought. The maize Glossy2 (Gl2) and Glossy2-like (Gl2-like) genes, homologous to the Arabidopsis Eceriferum2 (Cer2) gene, putatively encode members of the BAHD acyltransferase family of enzymes that have been implicated in regulating chain-length specificity of FAE, specifically in the terminal rounds of acyl-chain elongation. Work presented in this thesis aimed to characterize Gl2 and Gl2-like genes in two systems. Similar to the approach to characterize the members of the ZmFAE pathway, we utilized Saccharomyces cerevisiae as a heterologous platform to explore interactions between the ZmFAE system and GL2 and GL2-LIKE proteins. In parallel to the synthetic biology approach, Gl2 and Gl2-like were characterized in planta by analyzing the cuticular wax profiles of plants carrying mutant gl2 and gl2-like alleles. This work established that both Gl2 and Gl2-like contribute to fatty acid elongation and wax biosynthesis and showed that plants carrying mutant gl2 and gl2-like alleles have impaired cuticle function, as they are not as effective at mediating non-stomatal water loss.
Beyond their biological relevance, these findings underscore the broader potential of fatty acid metabolism to contribute to biotechnological applications. The final chapter of this thesis explores the capabilities of the thermophilic Actinobacterium, Thermobifida fusca, as a platform for consolidated bioprocessing systems to metabolize plant lignocellulosic biomass, highlighting its natural ability to generate fatty acid-derived molecules. Collectively, this research advances understanding of the maize fatty acid elongation and cuticular wax biosynthesis pathways and explores strategies for sustainable lipid production in microbial systems
Food web complexity alters phytoplankton persistence and resilience to nutrient pulses in experimental ecosystems
No full textIn aquatic ecosystems, greater food web complexity is theorized to increase persistence and resilience of primary production to pulse disturbances, yet experimental evidence is limited. We simulated two storm-induced pulse disturbances by adding nutrients (~ 3%–5% increase in ambient concentrations) to three ponds with low, intermediate, and high food web complexity and compared to reference ponds. We evaluated the ecological stability of primary production by quantifying persistence as the number of days it took chlorophyll-a or ecosystem metabolism to deviate significantly from reference conditions and resilience as the time to recover to reference conditions following each disturbance. We also evaluated if a critical transition occurred following the disturbance. The high complexity pond did not significantly deviate from reference conditions following either nutrient pulse, suggesting high ecological stability. The intermediate complexity pond had lower stability, with persistence relatively consistent at 18 and 24 d after each nutrient pulse, and resilience trending toward a substantial increase from 23 d to less than a week before the experiment concluded. Stability was lowest in the low complexity pond where persistence decreased from 24 d to just 8 d and resilience decreased from 5 to 22 d. There was also evidence of a critical transition after the first pulse in the low complexity pond, but not for higher complexity ponds. This experiment provides strong support that food web connectivity and food chain length can aid in buffering aquatic ecosystems against increasing and intensifying by influencing persistence and resilience to repeated nutrient pulses.This article is published as Butts, Tyler James, Robert A. Johnson, Michael Weber, and Grace Marie Wilkinson. "Food web complexity alters phytoplankton persistence and resilience to nutrient pulses in experimental ecosystems." Limnology and Oceanography 71 (2026): e70319. https://doi.org/10.1002/lno.7031
Synthesis-enabled discovery and crystal chemistry of rare earth silicon pnictides
No full textMetal tetrel pnictides represent an underexplored and promising class of materials with potential applications in energy conversion and storage. Featuring a flexible covalent tetrel-pnictide backbone, these materials can accommodate a variety of metals – including alkali, alkaline earth, and transition metals – forming diverse structures of varying dimensionalities. The exploration of rare earth tetrel pnictides, particularly those containing early lanthanides, is hindered by inherent synthesis challenges. Traditional high-temperature solid state synthesis from elements favors the formation of stable binary pnictides due to the mismatch in reactivity between volatile pnictogens and refractory metals and silicon. By leveraging non-traditional solid state synthesis approaches and critical mechanistic insights from variable-temperature in situ diffraction, several new ternary Ln-Si-Pn and quaternary Ln-M-Si-Pn compounds (Ln = La, Ce; M = Mn, Pt, Au; Pn = P, As) were discovered. Detailed investigations revealed diverse structural chemistry, including temperature-dependent polymorphism, novel structure types, and unusual metal coordination environments. In main group-rich compositions, homoatomic Pn-Pn bonding emerges as a defining motif, forming 2D square nets, 1D cis-trans chains, and rare 0D cyclo-[Pn4] rings, while metal-rich compositions adopt distinct structures. This work highlights the power of predictive synthesis in uncovering novel materials with tunable properties for the rational design of tetrel pnictides for diverse applications
Comparative Population Genomics of Relictual Caribbean Island Gossypium hirsutum
No full textGossypium hirsutum is the world's most important source of cotton fibre, yet the diversity and population structure of its wild forms remain largely unexplored. The complex domestication history of G. hirsutum combined with reciprocal introgression with a second domesticated species, G. barbadense, has generated a wealth of morphological forms and feral derivatives of both species and their interspecies recombinants, which collectively are scattered across a large geographic range in arid regions of the Caribbean basin. Here we assessed genetic diversity within and among populations from two Caribbean islands, Puerto Rico (n = 43, five sites) and Guadeloupe (n = 25, one site), which contain putative wild or introgressed forms. Using whole-genome resequencing data and a phylogenomic framework derived from a broader genomic survey, we parsed individuals into feral derivatives and truly wild forms. Feral cottons display uneven levels of genetic and morphological resemblance to domesticated cottons, with diverse patterns of genetic variation and heterozygosity. These patterns are inferred to reflect a complex history of interspecific and intraspecific gene flow that is spatially highly variable in its effects. Wild cottons in both Caribbean islands appear to be relatively inbred, especially the Guadeloupe samples. Our results highlight the dynamics of population demographics in relictual wild cottons that experienced profound genetic bottlenecks associated with repeated habitat destruction superimposed on a natural ecogeographical distribution comprising widely scattered populations. These results have implications for conservation and utilisation of wild diversity in G. hirsutum.This article is published as Ning, Weixuan, Guanjing Hu, Daojun Yuan, Mark A. Arick, Chuan‐Yu Hsu, Zenaida V. Magbanua, Olga Pechanova et al. "Comparative population genomics of relictual Caribbean island Gossypium hirsutum." Molecular Ecology 35, no. 2 (2026): e70239. https://doi.org/10.1111/mec.70239This work was supported by National Science Foundation Plant Genome Program, 141589. Cotton Incorporated, 22-605. USDA ARS Non-Assistance Cooperative Agreements, 58-6066-0-066, 58-6066-0-064
The effects of high-level factors on cybersickness
No full textCybersickness remains a significant barrier to the widespread adoption of virtual reality (VR), despite advances in hardware and growing interest in applications across industries such as gaming, education, healthcare, and defense. This dissertation investigates how high-level factors—including scene complexity and attentional load—contribute to the onset and experience of cybersickness in immersive VR environments. The research is structured around two main studies with three sets of participants, each targeting specific research goals.
The first study introduces a novel VR research platform called the Pendulum Chair, designed to enable controlled and repeatable experimentation in cybersickness research. Unlike passive environments commonly used in prior work (e.g., roller coasters), the Pendulum Chair provides an interactive "spinning world" environment with egocentric rotation, allowing precise manipulation of optic flow, scene complexity, and task demands. The platform was validated through an empirical study involving 56 participants who completed tasks in varying visual scenes and other settings. The results showed that participants experienced cybersickness in all tested conditions, supporting the platform's potential for flexible use in future research.
Building on the platform, the second phase of the first study investigated how scene complexity, particularly optic flow (a lower-level, more perceptual factor) and familiarity (a higher-level, more cognitive factor), influenced cybersickness and task performance. Using a between-subjects design, 44 participants (a subset of the 56 total participants) interacted with either a simple or complex VR scene while balancing on the Pendulum Chair. No significant differences in cybersickness or performance were found between the conditions. This result suggests that scene complexity, when defined by optic flow and familiarity alone, is not sufficient to predict cybersickness, and underscores the need for more definitions and measurement approaches.
In a follow-up analysis (the third phase of the first study), the relationship between scene complexity, workload, presence, and cybersickness was explored using data from the experiment. Results demonstrated meaningful correlations between participants' reported workload, their sense of presence, and cybersickness symptoms, highlighting the importance of considering task-related variables in virtual environment design.
The second major study focused on the role of visual attentional load and individual differences in shaping cybersickness. In this between-subjects experiment, participants performed VR tasks designed with two levels of attentional demand. Findings revealed that lower visual attentional load conditions were associated with significantly lower levels of cybersickness, suggesting that decreased attentional engagement may serve as a protective buffer. Furthermore, individual differences—including sex and video game history—moderated the relationship between attentional load and cybersickness severity, reinforcing the importance of personalized design in VR systems.
Collectively, the findings from this dissertation contribute to the understanding of how environmental and task-related variables interact to influence cybersickness. The Pendulum Chair emerges as an open-source research platform that can support future experimental work across a range of VR contexts