VTechWorks
VTechWorks provides global access to Virginia Tech scholarship, including journal articles, books, theses, dissertations, conference papers, slide presentations, technical reports, working papers, administrative documents, videos, images, and more by faculty, students, and staff. Faculty can deposit items to VTechWorks from Elements, including journal articles covered by the University open access policy. Email vtechworks@vt.edu for help.
Open Access Policy
Virginia Tech's open access policy enables researchers to deposit the accepted version of scholarly articles with no embargo.
Theses and Dissertations
Virginia Tech was first in the world to require ETDs in 1997, and continues to add scans of older theses and dissertations.
Open Textbooks
More than 40 freely available and openly licensed textbooks are among our most downloaded items.
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Recent Submissions
From Forest Floors to Pharmacology: Elucidating Millipede Defensive Alkaloids for Drug Discovery
Banks, Margaret P. (Virginia Tech, 2025-04-01)
Millipedes are some of the oldest animals on earth, evolving over 400 million years ago (mya). The subterclass, Colobognatha evolved 99 mya and are largely understudied compared to other classes of millipedes. Like most other millipede classes, Colobognatha possess repugnatorial glands, which store alkaloids as defensive compounds. However, they have also evolved unique characteristics that set them apart from all other millipedes, including distinct anatomy, group behavior, brood care, and the production of terpenoid alkaloids. Prior to 2020, only 11 alkaloids were known. Herein, a total of 25 new terpenoid alkaloids are reported coming from three different genera, all belonging to the same order. Key findings include the discovery of indolizine and quinolizidine alkaloids (e.g., hydrogosodesmine, homogosodesmine and homo-hydrogosodesmine) from the defensive secretions of various Brachcybye species (Chapter 2), the discovery of the ischnocybine alkaloids from the defensive secretions of Ischnocybe plicata (Chapter 3), and the discovery of the andrognathines and andrognathanols from the defensive secretions of Andrognathus corticarius (Chapter 4). The structure elucidation of each utilized modern techniques, including 2D NMR, HRMS, DFT, ECD, chemical synthesis, and Mosher's analysis. Many of these new alkaloids represent new natural product classes with carbon backbones that are unprecedented in the literature. Biological and ecological evaluation revealed the new alkaloids deter ants, a common predator to millipedes (Chapter 3), and this led to the discovery that a subset of the alkaloids potently binds to sigma-1 receptor (ischnocybine A: Ki 14 nM), while others bind to sigma-2 (homo-hydrogosodesmine hydrate: Ki 260 nM). Furthermore, ecology studies revealed that the alkaloid production is conserved over large geographical regions, accumulated as the millipedes gain segments and are actively secreted through the ozopores when physically agitated. These discoveries provide insights into a potential biosynthetic pathway shared by all Platydesmida millipedes and support the hypothesis that alkaloid biosynthesis in this order is evolving toward greater simplicity.
First-In-DOg HISTotripsy for Intracranial Tumors Trial: The FIDOHIST Study
Vezza, Christina Renny (Virginia Tech, 2025-04-01)
Objective: Brain tumors represent some of the most treatment refractory cancers, and there is a clinical need for additional treatments for these tumors. Domesticated dogs are the only other mammalian species which commonly develop spontaneous brain tumors, making them an ideal model for investigating novel therapies. Histotripsy is a non-thermal ultrasonic ablation method that emulsifies tissue through acoustic cavitation. The primary objectives of this prospective study were to assess the feasibility and safety of histotripsy to ablate naturally occurring canine brain tumors. Secondary endpoints included characterization of magnetic resonance imaging (MRI) responses to histotripsy treatment, and exploratory immunogenomic tumor response analyses.
Methods: The study design utilized a treat and resect paradigm, where tumors were approached using craniotomy, partially ablated with histotripsy delivered through the cranial defect, imaged with MRI, and then resected. Dogs were evaluated with clinical, brain MRI, immunopathologic, and genomic examinations before treatment, intraoperatively, and 1, 14, and 42 days post-treatment. Here we report the results of the three dogs with meningiomas, all of which were treated with a custom eight element 1 MHz histotripsy transducer at a pulse repetition frequency of 100 Hz and a treatment dosage of 400 pulses/point.
Results: Histotripsy was successfully delivered to all dogs, resulting in histopathologic evidence of ablations that were sharply demarcated from untreated tumor, with measured treatments approximating planned volumes in 2/3 dogs. One dog experienced an adverse event consisting of transient cerebral edema that was possibly attributable to histotripsy. Histotripsy ablations could be grossly visualized and identified on MRI, with features consistent with hemorrhage and necrosis. Significant expression or upregulation of the damage associated molecular pattern HMGB1, cytokine-cytokine receptor interaction, and NF-b signaling pathways were observed in histotripsy treated tumors.
Conclusion: Ablation of canine meningiomas with histotripsy through an open cranial window was feasible and clinically well tolerated.
Towards Improving Students' Software Testing Practices using Modified Mutation Testing
Mansur, Rifat Sabbir (Virginia Tech, 2025-04-02)
Mutation testing (MT) is a powerful technique for evaluating the quality of software test suites by introducing small faults, called ``mutations,'' into code to assess if tests can detect them.
While MT has been extensively applied in the software industry, its use in programming courses faces both computational and pedagogical barriers.
My research investigates the successful integration of MT in a post-CS2 Data Structures and Algorithms (DSA) course with 3-4 week long programming projects.
Through a comprehensive study across multiple semesters, I investigated three key aspects: the computational demands of MT in an educational auto-grading system, the effect of MT on student test suite quality and coding practices, and the development of a framework for effectively integrating MT in programming courses.
Initially, the implementation of standard MT showed mixed results due to inadequate stock feedback.
This prompted me to develop a tailored approach that modified MT feedback, while also incorporating additional documentation and training materials.
I also observed a noticeable increase (30-50 seconds per submission) in the auto-grader's processing time and feedback turnaround time when using MT, raising concerns about potential server overload.
At the same time, the collection of changes made to the environment and requirements as part of this intervention led to an overall reduction in the number of submissions per student needed to complete the projects.
My findings suggest that students using modified MT, as a group, demonstrated higher quality test suites and wrote better solution code compared to students whose test suites were graded on code coverage.
This version of MT with modified feedback also showed positive results in student understanding and application of MT principles compared to MT with stock feedback.
Analysis of IDE activity data, code submissions, and 38 semi-structured student interviews led me to provide a framework for introducing MT as an effective intervention.
Thus, my research provides a framework for effectively integrating MT in programming courses, contributing to improved student test suite development and offering practical guidelines for instructors introducing MT in undergraduate Computer Science courses.
Frustration and its impact on search and rescue canines
Dickinson, Sally; Feuerbacher, Erica N. (Frontiers Media, 2025-03-07)
Despite advances in modern technology, dogs remain the primary detection tool in search and rescue (SAR) missions, locating missing persons across diverse and dynamic environments, including wilderness, avalanche zones, water, and disaster areas. Their exceptional olfactory abilities, combined with their capacity to process complex discrimination tasks and adapt to varied environmental stimuli, make them uniquely suited for this work. However, SAR operations can be both physically and psychologically demanding, requiring sustained focus, endurance, and consistent performance under stressful conditions. Frustration, a form of psychological stress, arises when a dog encounters blocked access to a goal or when an expectation is violated, triggering physiological and behavioral changes that may impact performance. This study investigated the physiological and behavioral responses of SAR dogs to two distinct stress conditions: psychological stress induced by frustration and physiological stress induced by moderate exercise. We measured heart rate variability as an indicator of autonomic nervous system response to stress and analyzed search task performance to assess how frustration and exercise affected the dogs’ latency and accuracy in executing their trained final response to the target odor. Our results revealed significant decreases in heart rate variability following frustration and increased latency in the search task, suggesting that frustration had a more pronounced impact on the dogs’ physiological state and performance compared to exercise. By examining the effects of psychological and physiological stress, this study contributes to a deeper understanding of how different stressors influence SAR dog performance and welfare. These findings provide valuable insights for optimizing training methodologies and operational preparedness, ensuring both the effectiveness and well-being of SAR dogs in the field.
Gun Violence in the COVID-19 Era: Using Multiple Databases to Describe the Experience in Buffalo, NY
L'Huillier, Joseph C.; Nordin, Andrew B.; Nair, Veer V.; Cantor, Brittany L.; Tadlock, Bryan; Friend, Brianna; Boccardo, Joseph D.; Yu, Jihnhee; Lukan, James; Lillvis, Denise F.; Bass, Kathryn D. (Sage, 2024-12-24)
Objectives: In 2020, the public health crises of gun violence and novel coronavirus (COVID-19) collided and interventions to decrease COVID-19 transmission displaced millions of Americans from normal activity. We analyzed the effects of COVID-19 and its resultant shutdowns on gun violence in Buffalo, NY.
Methods: We queried the Gun Violence Archive (GVA) and the hospital databases from the 2 level 1 trauma centers which serve Buffalo firearm victims between March 15th and June 24th, 2020 ("COVID") and the same time period for years 2013 (hospital data)/2014 (GVA data) through 2019 ("pre-COVID") and 2021 through 2022 ("post-COVID"). Data points collected included number of daily victims, victim age, gender, and morbidity/mortality. Bivariate and multivariate analyses were used to compare gun violence in these 3 periods.
Results: There were 518 and 913 victims in the GVA and hospital data sets, respectively. Bivariate analyses showed fewer incidents on Saturdays during the pandemic in both data sets (P < 0.05). Multivariate analyses demonstrated no association between number of gun violence victims and time period in either data set (P > 0.05).
Conclusions: There was no change in number of gun violence victims during the COVID-19 shutdowns compared to pre-COVID and post-COVID periods in Buffalo, NY. However, there was a change in the weekly temporality of gun violence during the COVID pandemic. Multiple databases are needed to accurately capture gun violence from an epidemiologic perspective.