DRUM - Digital Repository at the University of Maryland
DRUM collects, preserves, and provides public access to the scholarly output of the university. Faculty and researchers can upload research products for rapid dissemination, global visibility and impact, and long-term preservation.
Submit to DRUM
To submit an item to DRUM, login using your UMD credentials. Then select the "Submit Item to DRUM" link in the navigation bar. View DRUM policies and submission guidelines.
Equitable Access Policy
The University of Maryland Equitable Access Policy provides equitable, open access to the University's research and scholarship. Faculty can learn more about what is covered by the policy and how to deposit on the policy website.
Theses and Dissertations
DRUM includes all UMD theses and dissertations from 2003 forward.
List of Communities
Collections Organized by Department
UM Community-managed Collections
Recent Submissions
Groundwater Contamination and Property Values: A Hedonic Price Analysis
(2024) Keane, Jack; Cropper, Maureen
About 15% of the United States population (~43 million people) rely on private wells for their source of drinking water. This water is not regulated by the Environmental Protection Agency, and as a result, the water in these wells can contain harmful contaminants (e.g., arsenic, nitrates, and nitrites) that go undetected by homeowners unless otherwise tested. Using a dataset of housing transactions (n=3,908) in the Orlando, Florida Metropolitan Statistical Area, I examine the impact of testing well water on the property value at time of sale. In Florida, not all homes with wells are tested before sale. I address the possibility of selection bias by using a subsample of homes from this dataset (n=1,566) that had all tested their well water before being sold. Using a hedonic pricing model, I test the impact of a well water test finding a contaminant above the detectable limit on sales price, controlling for housing characteristics, geospatial characteristics, and the date of sale. My results indicate a 10% decrease in property value when a well test revealed a contaminant to be above the detectable limit, relative to properties with well tests that did not reveal any contaminant above the detectable limit. The most robust, significant effects are found when homes were tested within a 3-year window prior to transaction. This has implications for the public health and financial stability of homeowners using private well water.
Silicone Fish Tail Actuator Capable of Variable Stiffening
(2024) Abrishamian, Shirah Shoshanah Ariel; Lena, Johnson; Huertas-Cerdeira, Cecilia
This work documents the creation of a fish-inspired robot actuator - from the conceptual design to a functional silicone model. The effect between the variable stiffness of a fish body and swimming efficiency has been a research subject in recent years. Often anatomy or function of an organism will inspire technological designs, particularly within the study of robotics. Animals have flexible anatomy for a range of possible maneuvers, and why fish-inspired robots are a popular choice in research. Studies have suggested a key to swim speed and efficiency in fish has been through tunable musculature. While muscle stiffness is difficult to measure in live fish, there is strong, natural evidence from several species, such as sunfish and tuna fish, showcasing this idea. Promoting inspired designs is the next step in improving robot performance. The deceptively simple appearance of typical fish combined with the numerous species' traits provides several possible robot designs. The robots can be objectively simple, with a trivial body and motor design to observe simple caudal fin motion. Or they can be exceptionally complicated if the research chooses to explore the nuances of fish anatomy and physiology, and how the impact on fish swimming in nature translates into an engineered construct. This would be beneficial due to the close relationship between bio-inspired design and soft robotics, fish bodies make a prime testing ground for soft robotics. No matter the simplicity, these robot designs can then be tested to gather valuable experimental data. This collaboration of technology and analysis then results in robots with advanced designs and special maneuvering capabilities. This research project aims to develop a tuna-inspired tail actuator capable of variable stiffness via a pneumatic system. Once attached to a 3D-printed fish body, it will be used to observe vorticity changes in fluid.
Draco Lizard-Inspired Robot for Structure Collapse Search
(2024) Phillips, Savannah; Johnson, Lena
Many high-stress situations can be difficult to navigate for first responders. Scenes such as active fires and building collapses require precise response tactics in order to minimize risk to first responders and victims alike. Disaster response tends to leave outcomes up to chance as a result of the unpredictable nature of these situations. Introducing robots into disaster response may help reduce uncertainty. Specifically, engineering robots to perform reconnaissance and relay critical information could greatly mitigate the risk posed to first responders entering dangerous scenes. My aim is to design a robot that possesses the gliding and crawling capabilities of the draco lizard. Draco lizards have unique wings that are used to glide amongst trees. My goal is to incorporate this gliding system into the robot, enabling it to be deployed to disaster sites with ease and reducing the workload for first responders. Equipped with cameras, the robot will be able to relay footage of the disaster scene for monitoring. Additionally, a thermal sensing system permits the transmission of quantitative data on potentially hazardous conditions, aiding in the locating of victims and ensuring informed and safer rescue operations.
Designing a Fish-like Robot That Can Swim on Water and Walk on Land
(2024) Garcia, Jimmy; Johnson, Lena
The Chesapeake Bay offers a scenic escape but struggles with excessive algae growth, particularly in forested wetlands. To address this, we are developing a robotic fish with a unique drivetrain that allows it to navigate both water and land, targeting hard-to-reach landscapes - like forested wetlands - as this is where excessive algae growth concentrates.
Throughout our research, we discovered the Pleco fish - a fish that can swim on water and walk on land using its tail fin. We believe replicating this locomotion system will advance the development of algae cleanup robots. Because of this, we are designing our robot to use a dual-gated system; the robot will have one drivetrain with two functions - swimming and walking.
To develop our robot, we first focused on three key areas: the body, tail, and locomotion system (swimming and walking). We built a prototype that navigates water and makes rudimentary walking motions on land. However, it uses two swimming and walking movement systems, which are still limited. We tested the robot’s aquatic abilities via a trial run in a controlled, clean pool at the University of Maryland, College Park’s Neutral Buoyancy Research Facility.
We are trying to iterate the design of the current drivetrain system and integrate the swimming and walking capabilities into one dual-gated system. This system should allow the robot to swim and walk on water without utilizing separate movement systems.
We hope these new iterations will bring us closer to replicating the locomotion of the pleco fish and help empower researchers and engineers to develop robotic platforms for cleaning algae in forested wetlands - a future of an algae-free bay.
Defining how two avian double-stranded RNA viruses affect lipid droplet (LD) formation and lipid metabolism in vitro
(2024) Liu, Ying-Rong (Megan); Kehlbeck, Declan; Egana-Labrin, Sofia; Brodrick, Andrew; Sunny, Nishanth; Broadbent, Andrew; Broadbent, Andrew
Some mammalian and fish double-stranded (ds)RNA viruses hijack lipid droplets (LDs) during their replication cycle, however, our understanding of how avian dsRNA viruses interact with LDs is incomplete. Here, we report data from avian reovirus (ARV) and infectious bursal disease virus (IBDV)- infected cells. Following ARV infection, there was a significant increase in the number (p < 0.0001) and size (p < 0.0001) of LDs compared to mock-infected controls, 6-24 hours post infection (hpi), in both immortalized LMH cells and primary gut cultures. Treatment with the ACCA inhibitor, TOFA, reduced ARV-mediated LD induction, indicating de novo lipogenesis was partially involved in their formation. Moreover, ARV infection decreased the expression of PGC-1α (p < 0.05) and ELOVL2 (p < 0.001). Previous reports demonstrated that inhibition of PGC-1α and ELOVL expression in mice led to cellular lipid accumulation and hepatic steatosis, suggesting ARV could upregulate LD synthesis by decreasing expression of these genes. However, it is unclear whether LD induction was pro- or anti-viral, since both TOFA treatment to inhibit LD synthesis, and oleic acid/palmitic acid treatment to overexpress LDs did not significantly alter ARV replication. In contrast, infection with IBDV did not substantially increase the size or number of LDs, or significantly reduce the expression of PGC-1α and ELOVL2. In contrast to some other dsRNA viruses like rotavirus and mammalian orthoreovirus, neither ARV nor IBDV cytoplasmic puncta colocalized with LDs. Taken together, our findings demonstrate that the two dsRNA viruses had distinct effects on cellular lipid metabolism.