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
Comprehensive overview of the macroscopic thermo-hydro-mechanical behavior of saturated cohesive soils
(Technobius, 2025-03-01) Kaliakin, Victor; Mashayekhi, Meysam
Understanding the effects of temperature on the hydro-mechanical behavior of geomaterials (i.e., soil and rock) has gained significance over the past three decades. This is due to new applications in which these materials are subjected to non-isothermal conditions. Examples of such applications include geothermal systems, nuclear waste disposal, and energy geo-structures. The analysis and design of such applications requires a thorough understanding of the macroscopic thermo-hydro-mechanical (THM) behavior of the geomaterials. Although various aspects of this behavior have been documented in the literature, a comprehensive overview of such behavior is lacking. This article presents such an overview of the macroscopically observed THM behavior of saturated cohesive soils.
Effective disc age: a statistical model for age-dependent and level-specific lumbar disc degeneration using magnetic resonance imaging (MRI)
(European Spine Journal, 2025-02-09) Newman, Harrah R.; Peloquin, John M.; Meadows, Kyle D.; Bodt, Barry A.; Vresilovic, Edward J.; Elliott, Dawn M.
Purpose
Intervertebral disc degeneration progresses with normal aging; yet common disc grading schemes do not account for age. Degeneration progression also varies between spine levels and is similarly not accounted for by current grading schemes. These limitations inhibit differentiation between discs with normal and expected aging (non-pathological) and discs with accelerated degeneration (which may be pathological). We sought to develop a statistical model to quantify normal age and spine level dependent disc degeneration.
Methods
Eighty-four asymptomatic adult subjects ranging evenly from 18 to 83 years old underwent magnetic resonance imaging (MRI) of the lumbar spine. Subject traits, MRI-derived disc geometry, and MRI biomarkers of T2 relaxation time were evaluated and used to develop a statistical model to predict effective disc age, the age at which normal aging would produce a disc’s observed phenotype.
Results
After evaluating several models, a 4-predictor model utilizing 1) subject height, 2) nucleus pulposus T2 relaxation time, 3) disc mid-sagittal area and 4) disc 3D volume, optimally estimated effective disc age. The effective age closely tracked true age for spine levels L1-L5 (R2 ≈ 0.7, RMSE ≈ 10 years) and moderately tracked true age for L5-S1 (R2 = 0.4, RMSE = 14 years). The uncertainty in the effective disc age prediction was ± 3 years as assessed by fivefold cross validation.
Conclusion
We offer a data-driven, quantitative tool to quantify normal, expected intervertebral disc aging. This effective age model allows future research to target discs with accelerated degeneration.
The influence of urban and agricultural landscape contexts on forest diversity and structure across ecoregions
(Ecosphere, 2025-02-25) Schmit, John Paul; Johnson, Lea R.; Baker, Matthew; Darling, Lindsay; Fahey, Robert; Locke, Dexter H.; Morzillo, Anita T.; Sonti, Nancy F.; Trammell, Tara L. E.; Aronson, Myla F. J.; Johnson, Michelle L.
Forest patches in urban landscapes make outsized contributions to biodiversity, ecosystem function, and human health and well-being. However, urbanization can alter environmental conditions that underpin forest health. Most studies of forest health in urban landscapes have focused on few forest patches across a single metropolitan region, and synthesis is needed to understand broader patterns. We assessed variation among measures of forest health across land cover gradients and ecoregions by determining (1) whether the degree of urban, agricultural, and forested land surrounding a forest patch was reflected in differences in tree community composition, diversity, and structure and (2) whether these differences were consistent across ecoregions. We synthesized data from 17 observational studies (3334 plots) and remotely sensed land cover (1-km buffer) across four metropolitan regions (Baltimore–Washington DC, Chicago, New York City, and Philadelphia) spanning five ecoregions of the eastern deciduous forest of North America. Land cover surrounding forest patches differed among ecoregions, and forests were surrounded by heterogeneous land cover even in the most urbanized areas. Patterns of tree species composition and forest structure reflected landscape context. Forest patches surrounded by high canopy cover had greater or equal tree species diversity, density, basal area, and diversity of tree sizes relative to patches surrounded by highly agricultural or highly impervious landscapes. In contrast, there was little difference in structure and diversity between forests in highly agricultural and impervious settings. Tree species composition varied among ecoregions, yet tree community assemblages of forests in intensively urbanized areas were consistently distinct from those of forests in other contexts. Forest patches in the most urban and most agricultural landscapes shared predominantly native species communities and were characterized by low tree species diversity, basal area, and size class diversity, as well as high non-native tree abundance, highlighting commonalities among these intensive anthropogenic landscapes. These results point to both common challenges to forest health and common opportunities for forest stewardship in urban and agricultural landscapes.
A transaction-cost model of chronic specie scarcity and the evolution of monetary structures in constrained colonial economies
(Cliometrica, 2025-02-06) Grubb, Farley
A transaction-cost model of monetary choice is used to justify colonists’ claims that specie money for executing within-colony trades and paying local taxes was chronically scarce in Britain’s pre-nineteenth century North American colonies. This scarcity is shown to be the result of individual rational maximizing choice behavior given the constraints imposed on the colonies by their mother country. By contrast, the conventional quantity-theory-of-money, specie-flow model indicates that a chronic specie scarcity equilibrium is impossible. Implicit assumptions in the quantity-theory-of-money model are shown to not apply to these colonial economies. The transaction-cost model developed here builds on the Walrasian–Arrow–Debreu general equilibrium model by incorporating transaction costs and media-of-exchange structures into the market clearing mechanism. Specie (outside money) and non-specie-money media-of-exchange structures (inside monies), which have differing transaction costs, are added to the model. Those additions, along with import substitution and trade-control constraints, identify the plausible circumstances that yield a chronic specie scarcity outcome in a colony. Whether the individual rational maximizing monetary choices that produce chronic specie scarcity in a colony lead to sub-optimal or to optimal social welfare outcomes in that colony depends on what non-specie media-of-exchange structures emerge as the inside money in that colony.
Mayor Pete is Smart and Elizabeth Warren is Unlikable? Coverage of Warmth and Competence Traits in the 2020 Democratic Presidential Primary
(Politics & Gender, 2025-02-24) Conroy, Meredith; Cassese, Erin; Mehta, Dhrumil; Hammond, Ciera; Beail, Linda; Johri, Al; Long, Sean; Stecula, Dominik
Past work on media coverage of candidates for political office has explored gender differences in quantity, substance, and tone with mixed results depending on the office, race, and context. We draw on the stereotype content model (SCM) to examine gendered patterns of media coverage of candidates on the trait dimensions of warmth and competence in the 2020 U.S. Democratic presidential primary. Combining Natural Language Processing and manual analysis of news, we find that female candidates receive more negative than positive warmth coverage, while male candidates receive more tonally balanced warmth coverage, which suggests that female leaders are penalized on the dimension of warmth. Additionally, white women received more warmth coverage than women of color and women of color receive more competence coverage than white women. The findings suggest news media may portray white women and women of color candidates as lacking gender congruent traits like warmth but may portray white women as possessing role congruent traits like competence.