Institutional Repository

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

Faculty, staff, and graduate students who want their research material hosted in UDSpace should contact the University of Delaware Insitutional Repository team at openaccess@udel.edu.
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 Information website.

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Recent Submissions

Evolution of Magnetic Deflections at a Conversion Layer near the Alfvén Surface
(The Astrophysical Journal Letters, 2026-04-20) Payne, Dominic; Akhavan-Tafti, Mojtaba; Goodwill, Joshua; Badman, Samuel; Bandyopadhyay, Riddhi; Zank, Gary; Adhikari, Subash; Matthaeus, William; Shi, Chen; Stevens, Michael; Livi, Roberto; Rivera, Yeimy; Paulson, Kristoff
We examine the statistics of Alfvénic deflections in sub- and super-Alfvénic solar wind with particular focus on the magnetic deflection angle θ. Our findings are in general agreement with earlier studies suggesting that θ > 90° rarely occurs in sub-Alfvénic regimes. We find the upper limit of θ exhibits an identifiable trend with the Alfvén Mach number Ma, suggesting that gradual steepening of Alfvénic deflections with increasing Ma is a plausible mechanism controlling deflection angles in the young solar wind. Further analysis reveals that large velocity fluctuations (δv/v > 1) tend to be important in the largest sub-Alfvénic deflections with increasing contributions from δv∥ approaching Ma = 1, while few deflections in the super-Alfvénic regime exhibit such large velocity perturbations. We also determine the local ratio of radial Poynting flux SR to kinetic energy flux KR and find that large sub-Alfvénic deflection angles tend to be dominated by SR, while super-Alfvénic deflections are eventually dominated by the KR associated with the radial solar wind flow. Our results show that near the Alfvén surface (where Ma = 1), there is a critical region of parameter space where δv ∼ va and KR/SR ∼ 1. We refer to this region (where ) as the conversion layer. The conversion layer may play a significant role in the evolution of magnetic defections by providing the medium for converting magnetic energy to particle energy and likely driving the formation of magnetic switchbacks in super-Alfvénic solar wind.
The Impact of Social Status on Decisions to Punish and Trust
(Social and Personality Psychology Compass, 2026-04) Wilhelm, Andrea L.; Cloutier, J.; Kubota, Jennifer T.
Social decisions occur across various contexts, and this review highlights how an individual's social status can influence these decisions. We summarize psychological research on the impact of social status on decision making and propose extending the theoretical framework known as the Social Status Framework, to include considerations of how status shapes trust and punishment. We begin by defining the concept of social status and then examine its influence on two key areas of social interactions :punishment and trust. Additionally, we discuss the potential interactions between social status and other social identity characteristics within these dynamics. Finally, we propose promising directions for future research to explore the complex relationships between social status and decision making, specifically trust and punishment, across diverse contexts and among different populations.
A White-light Flare on the L1 Dwarf WISEP J190648.47+401106.8
(Research Notes of the American Astronomical Society (RNAAS), 2026-04-01) Southwick, Ashton; Honaker, Easton J.; Gizis, John E.; Clarke, Riley W.; Blask, Tyler; Petrie, Harrison
WISEP J190648.47+401106.8 is an L1 brown dwarf known for a powerful 2012 flare observed by Gemini North. Although M dwarf flares are common and well-studied, flares on cooler L dwarfs are less understood. We perform a time series analysis of spectroscopic data obtained during the event of the flare to investigate the temporal evolution of the Hα emission feature. We find an inverse relationship between peak amplitude and equivalent width, indicating that the emission feature narrows as the flare intensifies. Additionally, we modeled the white flare spectrum by adding a blackbody element component to a quiescent spectrum. The fits suggest a blackbody temperature of 12,850 ± 25 K during the flare, which is consistent with flare temperatures observed in early-type M dwarfs. These results offer insight into the heating process of magnetic activity in ultracool dwarfs, and highlight the need for UV observations to break the temperature-filling factor degeneracy.
Pretraining effective T5 generative models for clinical and biomedical applications
(PLoS One, 2024-04-17) Althabiti, Saad; Chen, Chuming; Alrowili, Sultan; Wu, Cathy; Vijay-Shanker, K.
This paper presents a study of the impact of corpus selection and vocabulary design on the performance of T5-based language models in clinical and biomedical domains. We introduce five different T5-EHR models, each pretrained from scratch using different combinations of clinical and biomedical corpora alongside domain-specific vocabularies. We evaluated these models across a variety of clinical and biomedical tasks to quantify the impact of pretraining data and vocabulary tokenization choices on downstream performance. Our findings reveal the importance of aligning both pretraining corpus and vocabulary with the target domain. Models pretrained exclusively on clinical data achieve superior performance on clinical tasks, while adding biomedical data contributes only marginal gains in most cases, with a few exceptions. Similarly, the choice of vocabulary significantly influences model performance, with clinical-specific vocabularies outperforming general biomedical vocabularies in tasks requiring a deeper understanding of clinical language. Also, the T5 generative models perform competitively with state-of-the-art discriminative models on several biomedical benchmarks, demonstrating strong generalization to biomedical domain. Overall, these results emphasize that task-specific selection of corpus and vocabulary is essential for optimizing model performance in clinical and biomedical natural language processing (NLP).
Tourisms’ Tristes Tropiques II: Cultural Landscapes
(eTropic: electronic journal of studies in the Tropics, 2026-04-11) Guerrón Montero, Carla; Lundberg, Anita
In this second special issue on “Tourisms’ Tristes Tropiques” we explore “Cultural Landscapes” socio-culturally and ecologically to show how they are intertwined with historical, colonial, and neocolonial aspects of tourism. The anthropology of tourism and critical tourism studies recognize tourism as both an industry and a cultural phenomenon, and this dual approach provides a lens for exploring how cultural landscapes are created, transformed, activated, and morphed by tourism. In this Introduction, we discuss how such studies have contributed to a nuanced and careful understanding of tourism's effects on cultural landscapes. The title of this special issue pays homage to Lévi-Strauss’s Tristes Tropiques, a memoir that, in many ways, anticipated the subfields explored here. Although Tristes Tropiques remains a controversial text, on its publication in 1955, it presented an intrepid indictment of racism and colonialism, and of travellers whose very act of mobility contributes to both. In this second issue, we venture across a range of tropical landscapes, from South America and Northern Australia to the Seychelles and the Andaman Islands, through India, Southeast Asia, and finally to tropical Africa. The contributors examine how tourism shapes and is shaped by cultures, ecologies, heritage, and history. Their analyses reveal cultural landscapes that are not merely scenic backdrops but rich spaces that local people engage with to counter the touristic forces of commodification and inequality. This second part of the double special issue on “Tourisms’ Tristes Tropiques” complements the analysis established in the first issue on the subtheme of “Literary Travels,” and furthers that analytical journey.