55453 research outputs found
Sort by
Unsupervised Neural Networks for Anomaly Detection in Vehicular Transportation Systems
No full textCyber-Physical systems (CPSs) are at the core of modern critical infrastructures. The increasing complexity of CPSs makes them vulnerable to diverse cyber-physical attacks. Due to the safety-critical nature of transportation applications, any failures can result in massive economic losses, disrupt essential services, and even endanger human lives. Consequently, ensuring the security of vehicular transportation CPSs is of utmost importance.
Today’s complex CPSs generate massive amounts of unlabeled data. Labeling these data is an expensive and time-consuming task, and often requires domain expertise. Therefore, the existing supervised algorithms cannot take advantage of the abundance of real-world unlabeled data. Given these concerns, the adoption of unsupervised learning methodologies becomes imperative. Hence, we developed unsupervised deep learning-based anomaly detection systems (ADSs) that can be trained using such unlabeled data.
While traditional neural networks trained on one domain may excel within that specific context, they often fail when applied to data from a similar domain (not domain-adaptable). This is due to data distribution disparities, even when the feature space remains consistent. In such scenarios, learning domain-invariant features is essential for transferring knowledge from one domain to another. Unsupervised transfer learning-based domain-adaptable neural networks provide a great way to achieve this. Therefore, we developed domain adversarial ADSs that can effectively use cross-domain data to develop efficient ADSs.
Time-series unsupervised AD requires learning long-term dependencies from sequential data. Normal behavior data often exhibit these dependencies, while anomalies do not. This distinction aids in effectively differentiating anomalies from normal data. Generative AI (genAI) approaches, such as transformer architectures with attention mechanisms, excel at capturing these long-term interdependencies. This makes genAI approaches ideal for time-series anomaly detection in CPSs. Therefore, we develop novel genAI-based methodologies to improve anomaly detection in CPSs.
Thus, the main objective of this dissertation is to improve the security of CPSs in vehicular transportation applications using unsupervised AD. This main objective is delineated into three sub-objectives: 1) Develop combined cyber and physical anomaly detection frameworks to improve overall system health using unsupervised NNs, 2) Develop unsupervised transfer learning methodologies to improve AD performance in CPSs using cross-domain CPS data, and 3) Develop GenAI-based approaches for effective unsupervised ADSs
Modeling the Impacts of the Current and Projected Temperatures on Spongy Moth Population Dynamics
No full textThe spongy moth (Lymantria dispar) is an invasive forest pest that has caused significant ecological damage across the United States. Its invasion front is shaped by a number of factors, including temperature in both the northern and southern regions. With ongoing climate change, areas that were previously uninhabitable may become increasingly favorable for moth population establishment and expansion, while other areas may experience thermal stress limiting persistence. This study develops a temperature-driven population model to analyze how temperature affects the spongy moth population dynamics along the invasion front. This model incorporates temperature effects on fecundity, stage-specific survival rates, and the Allee threshold. Simulation results indicate potential range expansion under future warming projections, particularly along the northern edges of the invasion border. Northern areas may become increasingly suitable for establishment and growth, while southern populations may be constrained by thermal limits. However, this thermal stress does not render these areas uninhabitable because populations can still persist despite diminished survival rates. These findings emphasize how climate change may shift the spongy moth’s range and alter invasion risk across various regions. This study also highlights the complex and often conflicting effects of climate change on life stages and population fitness
The Design of a House
No full textPhotography lends itself to both damaging and facilitating connection, the camera at once a weapon of destruction and a catalyst for change. The Design of a House is a call to love deeply. In the aftermath of body trauma, I use portrait photography to reconnect with myself and others. Through making portraits, I bridge my own gap between fear and intimacy. Primarily working with film-based cameras and hand-sensitized photographic materials, I reintroduce touch through process. The slowness, delicacy, and tactility of these acts offer a safety I am learning to trust. When photographing myself, my mother, and my partner, I capture both the distance and closeness between us. I consistently choose to create harmony from opposing forces—grief and resurgence, pain and joy, masculine and feminine, light and dark
UNRAVELING THE REACTIVITY OF NITRATE ESTER EXPLOSIVES: INSIGHTS FROM FEMTOSECOND TIME-RESOLVED MASS SPECTROMETRY AND COMPUTATIONAL CHEMISTRY
No full textThis dissertation uncovers the ultrafast molecular mechanisms underlying the decomposition of nitrate ester explosives—nitroglycerin (NG), ethylene glycol dinitrate (EGDN), and amyl nitrate—through the integration of femtosecond time-resolved mass spectrometry and advanced computational chemistry. Although these compounds play fundamental roles in both military and civilian contexts, the precise molecular dynamics governing their pronounced reactivity and impact sensitivity have remained inadequately characterized. Our research establishes that low O–NO2 bond dissociation energies are the primary driver of ultrafast fragmentation and high reactivity in all three esters. The distinctive molecular architectures of these esters dictate their explosive properties: NG’s tri-nitrate configuration leads to exceptional energy release and high sensitivity; EGDN’s structure imparts notable low-temperature stability; and amyl nitrate’s singular nitrate group results in reduced energetic output but relevance for non-explosive applications. Fragmentation is shown to proceed predominantly via homolytic cleavage of nitrate groups, with mass spectrometric signatures closely reflecting the underlying molecular frameworks. Complementary density functional theory (DFT) calculations elucidate the electronic structure changes that accompany ionization and bond rupture, mapping key transition states and relative energetics. These computational predictions, benchmarked against experimental observables, enable molecular-level insight into reactivity, rate trends, and impact sensitivity for all three systems. Ab initio molecular dynamics (AIMD) simulations, performed in parallel with experiment, capture real-time dissociation trajectories following ionization. The timescales i and ii, and the primary fragmentation pathways observed in AIMD ensemble data, quantitatively agree with those extracted from femtosecond pump-probe experiments, providing strong concordance between theory and measurement and confirming the proposed mechanisms. The convergence of ultrafast experimental techniques and quantum-chemical modeling enables the formulation of robust structure–reactivity relationships, linking bond dissociation energies and key conformational motifs to macroscopic decomposition rates and sensitivities. These insights deepen fundamental understanding while also guiding the rational design of safer explosives and advanced propellants. This work pioneers femtosecond-resolved studies of nitrate ester dynamics and lays the groundwork for future explorations across broader families of energetic compounds
Opioid Tolerance and Withdrawal in the Mouse Colon
No full textConstipation is a major clinical obstacle associated with opioids, prompting patients to discontinue treatment due to pain, discomfort, and psychosocial stressors. Moreover, chronic users become tolerant to the analgesic effects of opioids, but not to their constipating effects. Upon cessation of long-term treatment, serious diarrhea–among other somatic signs of withdrawal–may ensue. These symptoms become a driving factor for relapse, causing patients to restart opioid treatment. In this study, we aim to understand mechanisms that contribute to opioid tolerance and withdrawal in the colon. Previous findings suggest that constipation occurs partly due to the colon’s lack of tolerance to opioids’ inhibitory effects on transit. Our data shows that colonic tissue which was exposed to 4 days of in-vivo ramping doses of morphine injections demonstrated similar basal motility compared to morphine-naive tissue, suggesting that tolerance develops in the colon. We also demonstrate naloxone-precipitated withdrawal behavior in these chronic morphine-treated tissue, demonstrating a link between colonic withdrawal and tolerance. Drawing upon previous work from our lab, we investigated the role of cholinergic signaling and how it may impact withdrawal. We are specifically interested in lynx1, a negative allosteric modulator of ɑ3ꞵ4 nAChRs. Chronic morphine-treated lynx1 knockout tissue experienced significantly heightened withdrawal compared to WT. This finding implicates cholinergic signaling as a major contributor in the colon’s withdrawal response and may propose lynx1 as an interventional candidate in attenuating GI withdrawal
FUNCTIONAL ANALYSIS OF LIGAND BINDING DOMAIN 2 OF OUTER SURFACE PROTEIN C OF BORRELIELLA BURGDORFERI
No full textLyme disease, caused by the spirochete Borreliella burgdorferi, is the most common vector-borne infection in North America. A critical determinant of early mammalian infection is outer surface protein C (OspC), a highly variable lipoprotein that is indispensable for spirochete survival but whose precise function remains unresolved. OspC has been proposed to mediate diverse roles, including complement evasion, adhesion, tissue dissemination, and antiphagocytic activity, supporting the view that it is a multifunctional virulence factor. Structural studies have identified two putative ligand-binding domains (LBD1 and LBD2), with LBD2 forming a solvent-exposed crown at the membrane-distal end of the OspC dimer.
To define the contribution of LBD2, eight site-directed mutants were generated in-cis at the native cp26 ospC locus of B. burgdorferi B31. All mutant strains expressed OspC on the surface and retained its α-helical fold and dimerization, yet none established infection in C3H/HeN mice, as measured by culture or seroconversion. Notably, six of the eight mutants exhibited punctate foci of OspC rather than the continuous circumferential distribution observed in the wild-type strain. Complementation with a wild-type ospC allele restored uniform surface localization and rescued infectivity, demonstrating that the integrity of LBD2 is critical for proper surface organization and in vivo function.
These findings identify LBD2 as an essential functional determinant of OspC and suggest that its contribution to infectivity stems from maintaining correct surface presentation or orientation rather than any single physicochemical property. This work establishes a framework for dissecting the molecular interactions that OspC mediates during early infection, providing new insights to guide the development of diagnostics and vaccines targeting OspC
Low Brass Studio Recital, video disc one
Get PDFVideo disc one of twoLow Brass Studio Recital, videoTuesday, April 10, 2025 at 8:00 p.m.Sonia Vlahcevic Concert HallW.E. Singleton Center for the Performing Arts922 Park Avenue | Richmond, Virgini
University Band, video
Get PDFEnsemble performance videoUniversity BandDuane Coston, conductorFriday, April 11, 2025 at 7:00 p.m.Sonia Vlahcevic Concert HallW.E. Singleton Center for the Performing Arts922 Park Avenue | Richmond, Virgini
The War on Degenerate Art
Get PDFHonorable mention in the 2025 Jurgen Banned Art Comics Contest.
A dark historical tale about the modernist and avant-garde painters and sculptors whose art was attacked and derided in the Nazi Party\u27s 1937 Degenerate Art Exhibitionhttps://scholarscompass.vcu.edu/jurgen/1029/thumbnail.jp
Breaking Barriers Yolanda Hall\u27s Mission to Empower Youth
No full textThis video highlights the collaborative efforts of Yolanda Hall, a dedicated community partner working closely with the Greater Richmond Youth Development Network (RichmondYDN), housed at the Mary and Frances Youth Center within the Division of Community Engagement at Virginia Commonwealth University (VCU). Through Hall’s insights, the video explores the impact of community-based partnerships in advancing youth development. The discussion emphasizes the role of collaborative engagement, mentorship, and evidence-based practices in creating sustainable support systems for youth