Masters Theses
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- Mosquito Species Abundance, Diversity and Arbovirus Prevalence across Different Land-use in The GambiaCamara, Muhammed (Virginia Tech, 2025-11-06)Mosquito-borne arboviruses represent an escalating public health threat across sub-Saharan Africa, yet surveillance remains limited in many countries, including The Gambia. This study investigates mosquito species abundance and diversity, as well as the arbovirus prevalence across human, agricultural, and sylvatic habitats in The Gambia, accounting for ecological and seasonal variation. Adult mosquito samples were collected using a BG-Pro and CDC light traps. Larval and egg collections were made using dippers and oviposition cups, respectively. Sampling was conducted across three regions and several periods of seasonality (dry season, early and late rainy season) from December 2021 to October 2022. Mosquitoes were morphologically identified to species, or the lowest resolvable taxonomic level. Over 40,000 mosquitoes representing 51 species across 12 genera were collected. Mansonia uniformis was the overall predominant species, particularly dominating collections from sylvatic and agricultural habitats, while Culex quinquefasciatus was the most abundant species in human inhabitated areas. The sylvatic and agricultural sites exhibited the highest species richness, with 45 identifiable species, whereas human habitation sites yielded 36 identifiable species. Mosquito abundance, species richness and Shannon diversity were significantly influenced by seasonality, with all peaking at the end of the rainy season, but showed no significant effects of habitat type or trap type. Mosquito pools were screened for arboviruses using isolation techniques on Vero cell culture; then isolates identified via reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing. Five pools have been confirmed to be Ngari virus (two pools), Bunyamwera virus (one pool) and Sindbis virus (two pools), representing the first confirmed detection of these arboviruses in field-collected mosquitoes from The Gambia. Interestingly, all five pools were identified during the late rainy season across inland sylvatic, agricultural, and human-inhabited landscapes, highlighting the possible role of ecological context in shaping arbovirus transmission risk. This study provides the first systematic, habitat-inclusive assessment of mosquito biodiversity and arbovirus circulation in The Gambia. Findings highlight the presence of competent vector species and potential silent virus circulation in understudied regions, reinforcing the need for integrated entomological and virological surveillance.
- Physics-Informed Machine Learning Methodologies Using RAPID for Predicting Eigenvalue and 3-D Fission Distribution in JSI TRIGA Mark-II Research ReactorFranck, Timothy Thomas (Virginia Tech, 2025-11-05)The most common methodologies for high-fidelity simulations of nuclear reactors are very slow and require significant computer resources. Machine learning (ML) enables computers the ability to learn from data, allowing well-trained models to produce results quickly and accurately. However, the challenges of machine learning involve proper algorithm selection and, more importantly, the quantity/quality of the data. The RAPID code system enables very fast and accurate simulations of nuclear reactor systems. RAPID's algorithms have been both computationally and experimentally validated using the JSI TRIGA Mark-II research reactor. Accordingly, RAPID was used to generate a complete physics-informed dataset for training ML models to predict the system eigenvalue (keff) and 3-D fission neutron distributions as a function of various control rod configurations. A total of 157,324 high-fidelity simulations were performed to generate training and testing datasets, which contain keff and 3-D fission distributions. The ML models analyzed include linear regression, polynomial regression, k-nearest neighbors (kNN), random forest (RF), and neural networks (NN). Results show that kNN regression is both fast and accurate for calculating keff, achieving an RMSE score of 26.37 pcm in under one second. For predicting 3-D fission distributions, ML models were evaluated across core and control rod fuel follower (CR-FF) regions. The NN model accurately predicted ~99 % of core fission values within ±0.5 % rel. diff. and ~98 % of the CR-FF fission values within ±10 % rel. diff. in under 10 seconds. Power peaking factors calculated from the NN model's predicted fission values fell within -0.39 % to 0.91 % rel. diff., demonstrating that larger errors in the CR-FF regions had minimal impact.
- VanishingBorjas, Emilia (Virginia Tech, 2025-10-24)Blending the uncanny with the familiar, this collection dives into Chicanx lives where characters grapple with memory, loss, patriarchal thinking, trauma, love, belonging, heartbreak, self-worth and other wound makers in order to move past survival and into a world where they can thrive.
- Evaluating the Value of Information Concerning Different Methods of Forest SamplingHorton, Jackson Davis (Virginia Tech, 2025-10-24)Forest inventory is essential for estimating stand value and assists with making informed management decisions. However, the compromise made between the cost of sampling methods during inventory, and the accuracy of the information gathered has not been fully recognized. This study evaluates the value of information across multiple sampling methods and intensities. The objectives focus on 1) evaluating measurement and travel time across multiple plot sizes, 2) comparing absolute present value errors across sampling intensities, 3) evaluating the impact of timber markets on absolute present value error, and 4) determining how sampling intensity affects the absolute harvest age error. Stands of a thinned loblolly pine plantation in Charlotte State Forest, Virginia were sampled using fixed-radius plots to inform a simulation study. An intensive sample was designated as the true optimal value during the comparison of absolute error values from the sample data. All inventory data were analyzed to compare accuracy across multiple sampling methods. The intensity of samples significantly influenced sampling error. Smaller plot sizes with decreased intensities increased error in estimates of absolute present value error and absolute harvest age error. Larger plots required fewer samples to obtain decreased error, but the cost associated with larger sample sizes increases the total inventory cost. The results confirm that as sample size and intensity increase, sampling error will decrease. However, in a management setting, mid-sized plots offer a balance between accuracy, cost, and time that provide reliable estimates without diminishing inventory costs. Forest managers can use the methodology presented in our study for their own management objectives and circumstances to determine a sampling design that is most suitable and efficient under their conditions.
- A senior high school for Blacksburg, VirginiaStaniunas, Joseph Paul (Virginia Polytechnic Institute, 1947)
- Condensation reactions Vanillin-Aniline and Vanillin- DimethylanilineAtkinson, Walter Ellsworth (Virginia Polytechnic Institute, 1949)
- Characteristics of a Virginia kyaniteSawyer, J. P (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1940)
- A study of the relation of Berberis canadensis Mill. to stem rust in VirginiaMatheny, Gallais E (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1939)
- Multi-routed job shop schedulingSoujanyam, Sirandasu (Virginia Polytechnic Institute and State University, 1989)
- Personal factors of operator related to various efficiency and living factors 620 bright tobacco farms, Pittsylvania County, Virginia, 1993Salem, Olive Augusta (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1937)
- Economic evaluation in energy planning: the experience of communities in the United StatesFlora, Rebecca Lee (Virginia Polytechnic Institute and State University, 1983)
- Phenotypic Characterization of Gluconobacter correlated with DNA/DNA homology studiesJones, Lori Michelle (Virginia Polytechnic Institute and State University, 1987)
- Three-dimensional and off-design studies of a mach 7.4 hypersonic inletPingali, Uma (Virginia Polytechnic Institute and State University, 1987)
- A decision support tool for the assessment of alternatives using fuzzy set theory and classical methodsHwang, Wan Cheng (Virginia Polytechnic Institute and State University, 1986)
- Biological treatability and inhibitory effects of a textile waste containing caprolactamBrown, Peter Christopher (Virginia Polytechnic Institute and State University, 1984)
- A book of drawingsDenegre, Joseph J (Virginia Polytechnic Institute and State University, 1986)
- Extreme racism, nationalism, and national identity in Germany from 1871-1993Kalckstein, Karl-Yorck (Virginia Polytechnic Institute and State University, 1993)
- Nutritional studies on Ceuthorrhynchidius horridus (Coleoptera: Curculionidae): an introduced weevil for the biological control of Carduus thistlesTrumble, John Thomas (Virginia Polytechnic Institute and State University, 1977)
- Economic rents attributable to Virginia's coastal wetlands as inputs in oyster productionWilson, J. R (Virginia Polytechnic Institute and State University, 1977)
- The treatability of stormwater runoff from an urban commercial catchment by settling and chemical coagulationAlexander, Scott Barry (Virginia Polytechnic Institute and State University, 1978)