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Full-Text Articles in Physical Sciences and Mathematics

Better Understanding Genomic Architecture With The Use Of Applied Statistics And Explainable Artificial Intelligence, Jonathon C. Romero Aug 2022

Better Understanding Genomic Architecture With The Use Of Applied Statistics And Explainable Artificial Intelligence, Jonathon C. Romero

Doctoral Dissertations

With the continuous improvements in biological data collection, new techniques are needed to better understand the complex relationships in genomic and other biological data sets. Explainable Artificial Intelligence (X-AI) techniques like Iterative Random Forest (iRF) excel at finding interactions within data, such as genomic epistasis. Here, the introduction of new methods to mine for these complex interactions is shown in a variety of scenarios. The application of iRF as a method for Genomic Wide Epistasis Studies shows that the method is robust in finding interacting sets of features in synthetic data, without requiring the exponentially increasing computation time of many …


Root Stage Distributions And Their Importance In Plant-Soil Feedback Models, Tyler Poppenwimer Dec 2020

Root Stage Distributions And Their Importance In Plant-Soil Feedback Models, Tyler Poppenwimer

Doctoral Dissertations

Roots are fundamental to PSFs, being a key mediator of these feedbacks by interacting with and affecting the soil environment and soil microbial communities. However, most PSF models aggregate roots into a homogeneous component or only implicitly simulate roots via functions. Roots are not homogeneous and root traits (nutrient and water uptake, turnover rate, respiration rate, mycorrhizal colonization, etc.) vary with age, branch order, and diameter. Trait differences among a plant’s roots lead to variation in root function and roots can be disaggregated according to their function. The impact on plant growth and resource cycling of changes in the distribution …


Assessing Kiln-Produced Hardwood Biochar For Improving Soil Health In A Temperate Climate Agricultural Soil, Emily J. Cole Nov 2015

Assessing Kiln-Produced Hardwood Biochar For Improving Soil Health In A Temperate Climate Agricultural Soil, Emily J. Cole

Doctoral Dissertations

Soil quality has become a major factor used in assessing sustainable land management and the overall environmental quality, food security, and economic viability of agricultural lands. Recently, biochar has been touted as having many potential uses as a soil amendment for improving soil quality, specifically improving cation exchange capacity, pH and nutrient availability. However, soil biology also plays a significant role in biogeochemical processes that influence soil health and should be included in a more comprehensive study of soil health. This dissertation describes 4 projects within the same 3-year field study with the cumulative purpose of better understanding the effect …


Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard Aug 2015

Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard

Doctoral Dissertations

The late-glacial transition to the Holocene, 15,000–11,600 cal yr BP, is an enigmatic period of dynamic global changes and a major extinction event in North America. Fire is an agent of disturbance that transforms the environment physically and chemically, and affects plant community composition. To improve understanding of the linkages between fire, vegetation, and climate over the late glacial and Holocene in the eastern U.S., I analyzed lake-sediment cores for charcoal and indicators of wood ash, and compared results to existing pollen records. A new microscopic charcoal record from Anderson Pond, Tennessee revealed high fire activity from 23,000–15,000 cal yr …


Steps Toward Butternut (Juglans Cinerea L.) Restoration, Sunshine L. Brosi Aug 2010

Steps Toward Butternut (Juglans Cinerea L.) Restoration, Sunshine L. Brosi

Doctoral Dissertations

Butternut (Juglans cinerea L.), a lesser-known relative of black walnut (Juglans nigra L.), is a native tree species beneficial for wildlife, valuable for timber, and part of the great diversity of species in the eastern forests of North America. Populations of butternut are being devastated by butternut canker disease, caused by the fungus Sirococcus clavigignenti-juglandacearum (V.M.G. Nair, Kostichka, & Kuntz), which is thought to be introduced to North America. The disease causes multiple branch and stem cankers that eventually girdle trees. Small population sizes, lack of sprouting, and shade intolerance exacerbates the disease and results in permanent losses of butternut …


Spatiotemporal Dynamics In A Lower Montane Tropical Rainforest, Robert Michael Lawton Aug 2010

Spatiotemporal Dynamics In A Lower Montane Tropical Rainforest, Robert Michael Lawton

Doctoral Dissertations

Disturbance in a forest’s canopy, whether caused by treefall, limbfall, landslide, or fire determines not only the distribution of well-lit patches at any given time, but also the ways in which the forest changes over time. In this dissertation, I use a 25 year record of treefall gap formation find a novel and highly patterned process of forest disturbance and regeneration, providing a local mechanism by examining the factors that influence the likelihood of treefall. I then develop a stochastic cellular automaton for disturbance and regeneration based on the analysis of this long term data set and illustrate the potential …