Institutional Repository

The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.

Faculty, staff, and graduate students can deposit their research material directly into UDSpace. Faculty may use UDSpace to fulfill the University of Delaware Faculty Senate Open Access Resolution, and in many cases may use it to fulfill open access requirements from grant funding agencies.
Departments can use UDSpace to publish or distribute their working papers, technical reports, or other research material.
UDSpace also includes all doctoral dissertations from winter 2014 forward, and all master's theses from fall 2009 forward.

To learn more about UDSpace, and how you can make your research openly accessible to the public, visit our UDSpace Policies website.

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Recent Submissions

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2024 KIDS COUNT in Delaware FOCUS on Public Policy

(University of Delaware Center for Community Research and Service, Newark, DE, 2024-05-01) Barlow, Janice; Nescott, Erin; Oberheim, Kelly; Perez-Rivera, Miranda; KIDS COUNT in Delaware Staff; KIDS COUNT in Delaware Staff

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Environmental drivers of biogeography and community structure in a Mid-Atlantic estuary

(Oecologia, 2024-02-14) Oleynik, Haley A.; Bizzarro, Joseph J.; Hale, Edward A.; Carlisle, Aaron B.

Estuaries include some of the most productive yet anthropogenically impacted marine ecosystems on the planet, and provide critical habitat to many ecologically and economically important marine species. In order to elucidate ecological function in estuaries, we must understand what factors drive community dynamics. Delaware Bay is the third largest estuary in the United States and hosts over 200 species of migrant and resident fishes and invertebrates. The Delaware Division of Fish and Wildlife has conducted two long-term trawl surveys at monthly intervals in Delaware Bay since 1966. The two surveys collect data on environmental conditions, species composition, and number of fishes and macroinvertebrates across different size classes and life histories. Using a suite of multivariate approaches including hierarchical cluster analysis, canonical correlation analysis, and permutational multivariate analysis of variance, we characterized the fish and macroinvertebrate community in Delaware Bay and found that community composition and environmental conditions varied across spatial and seasonal scales. We identified four distinct biogeographic regions, based on environmental conditions and community composition, which were consistent across surveys. We found that the community was driven primarily by gradients in temperature and salinity and that abundant, frequently occurring species in the Bay have well-defined environmental associations. Our work represents the first attempt to use an existing historical survey to better understand how environmental parameters influence diversity and distribution of macrofauna within Delaware Bay, providing insight into how abiotic variables, influenced by climate, may impact the Delaware Bay ecosystem and similar estuarine ecosystems worldwide.

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U.S. cereal rye winter cover crop growth database

(Scientific Data, 2024-02-13) Huddell, Alexandra M.; Thapa, Resham; Marcillo, Guillermo S.; Abendroth, Lori J.; et. al

Winter cover crop performance metrics (i.e., vegetative biomass quantity and quality) affect ecosystem services provisions, but they vary widely due to differences in agronomic practices, soil properties, and climate. Cereal rye (Secale cereale) is the most common winter cover crop in the United States due to its winter hardiness, low seed cost, and high biomass production. We compiled data on cereal rye winter cover crop performance metrics, agronomic practices, and soil properties across the eastern half of the United States. The dataset includes a total of 5,695 cereal rye biomass observations across 208 site-years between 2001–2022 and encompasses a wide range of agronomic, soils, and climate conditions. Cereal rye biomass values had a mean of 3,428 kg ha−1, a median of 2,458 kg ha−1, and a standard deviation of 3,163 kg ha−1. The data can be used for empirical analyses, to calibrate, validate, and evaluate process-based models, and to develop decision support tools for management and policy decisions.

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In-Ovo Glutamine Administration Enhances Intestinal Development and Functions in Broiler Chickens: Insights from Enteroid Models

(The Journal of Nutrition, 2024-04-10) Yu, Liang-en; Mann, Peter; Schlitzkus, Lydia; Ghiselli, Federico; Sanders, Mia; Hadimundeen, Abdallah; Li, Yihang

Background Early life events play significant roles in tissue development and animal health in their later life. Early nutrition, through in-ovo delivery, has shown beneficial effects on improving intestinal health in broiler chickens. However, the underlying mechanism is not fully investigated. A recently developed enteroid culture technique allows investigations on intestinal epithelial functions that are close to physiologic conditions. Objectives In this study, we evaluated the short- and long-term effects of in-ovo administration of glutamine (Gln) on intestinal epithelial development and functions by using intestinal enteroid culture and tissue electrophysiologic analysis. Methods A hundred eggs of commercial Cobb500 broilers were in-ovo injected with 0.2 mL of either phosphate-buffered saline (PBS) or 3% Gln at embryonic day 18 (E18). Chicks were killed on the day of hatch, and at 3- and 14-d posthatch. Enteroids were generated from the small intestine. After 4 d of culture, enteroids were harvested for 5-ethynyl-2′-deoxyuridine proliferation, fluorescein isothiocyanate-4 kDa dextran permeability, and glucose absorption assays. At day 3 (d3) and day 14 (d14), intestinal barrier and nutrient transport functions were measured by the Ussing chamber. The gene expression of epithelial cell markers, nutrient transporters, and tight-junction proteins were analyzed in both intestinal tissues and enteroids. Results In comparison with the PBS control group, in-ovo Gln increased intestinal villus morphology, epithelial cell proliferation, and differentiation, and altered epithelial cell population toward increased number of enteroendocrine and goblet cells while decreasing Paneth cells. Enteroids gene expression of nutrient transporters (B0AT1, SGLT1, and EAAT3), tight junction (ZO2), glucose absorption, and barrier functions were enhanced on the day of hatch. Long-term increases of intestinal di-peptide and alanine transport were observed at day 14 posthatch. Conclusions Together our results suggested that the in-ovo injection of Gln stimulated intestinal epithelium proliferation and programmed the epithelial cell differentiation toward absorptive cells.

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Early-season biomass and weather enable robust cereal rye cover crop biomass predictions

(Agricultural & Environmental Letters, 2024-02-13) Huddell, Alexandra; Needelman, Brian; Law, Eugene P.; Ackroyd, Victoria J.; Bagavathiannan, Muthukumar V.; Bradley, Kevin; Davis, Adam S.; Evans, Jeffery A.; Everman, Wesley Jay; Flessner, Michael; Jordan, Nicholas; Schwartz-Lazaro, Lauren M.; Leon, Ramon G.; Lindquist, John; Norsworthy, Jason K.; Shergill, Lovreet S.; VanGessel, Mark; Mirsky, Steven B.

Farmers need accurate estimates of winter cover crop biomass to make informed decisions on termination timing or to estimate potential release of nitrogen from cover crop residues to subsequent cash crops. Utilizing data from an extensive experiment across 11 states from 2016 to 2020, this study explores the most reliable predictors for determining cereal rye cover crop biomass at the time of termination. Our findings demonstrate a strong relationship between early-season and late-season cover crop biomass. Employing a random forest model, we predicted late-season cereal rye biomass with a margin of error of approximately 1,000 kg ha−1 based on early-season biomass, growing degree days, cereal rye planting and termination dates, photosynthetically active radiation, precipitation, and site coordinates as predictors. Our results suggest that similar modeling approaches could be combined with remotely sensed early-season biomass estimations to improve the accuracy of predicting winter cover crop biomass at termination for decision support tools. Core Ideas - Cereal rye winter cover crop biomass modeled on data from 35 site-years. - We found a strong relationship between early and late-season biomass. - Random forest model with early-season biomass and weather data performed well. - Similar approach could improve decision support tools for cover crop management. Graphical Abstract available at: https://doi.org/10.1002/ael2.20121 Effect size estimates from the generalized linear mixed effects model prediction late-season cereal rye cover crop biomass. All covariates were standardized, and significant relationships are indicated by *p < 0.05, **p < 0.01, and ***p < 0.001. Abbreviations CGDD cumulative growing degree days GLMM generalized linear mixed effects model PAR photosynthetically active radiation