University of Tennessee Institute of Agriculture
University of Tennessee, Knoxville: TraceNot a member yet
47048 research outputs found
Sort by
Saccadic Suppression of Luminance: Investigating the Impact on The Perception of Saccade’s Target
Get PDFSaccadic suppression is a transient reduction in visual sensitivity around saccades that helps maintain perceptual stability by minimizing the disruptive blur caused by rapid eye movements. While previous studies have shown that undetected flashes during saccades can still bias later visual judgments, how these suppressed stimuli might alter the subsequent perception of brightness of a saccade target remains underexplored. In this study, 8 participants (reduced from an initial 10 due to exclusion criteria) with normal or corrected-to-normal vision completed a total of 512 trials in a dimly lit room. In the saccade condition, participants made a 15° rightward eye movement toward a colored target while a ~10ms luminance flash was presented either 15ms or 25ms after saccade onset. In the fixation condition, participants maintained gaze on a fixation point while viewing the same target-flash sequence. After each trial, participants reported the target’s color from a predefined spectrum and indicated whether they detected a flash. Our repeated-measures ANOVA revealed that color category significantly modulated flash effects: late flashes induced notably larger color-report deviations in green and cyan, while high-luminance flashes disproportionately affected green, cyan, and purple targets. In contrast, there were no robust overall main effects of flash timing or luminance alone. These findings indicate that even brief, often undetected flashes selectively bias post-saccadic luminance judgments for certain hues. By demonstrating that suppressed luminance flashes “leak” into subsequent perception, this study provides new insight into the boundaries of saccadic suppression. These results support the view that saccadic suppression acts more like a dynamic filter, strong for low-level magnocellular signals yet partially permeable for color-specific information, thereby maintaining perceptual stability while still allowing some transient visual input to shape the final percept
Association between Sperm Metabolites and Field Fertility in Angus Bulls
No full textUnderstanding the causes of bull subfertility and developing reliable diagnostic tools are critical to reducing economic losses caused by reproductive failure in beef cattle. Currently, the primary method to evaluate bull fertility is a breeding soundness exam, but this does not provide a detailed account of intracellular processes that may be dysfunctional in normal appearing sperm cells from subfertile males. Metabolomic analysis of sperm from bulls with diverging field fertility may provide insights of sperm metabolism that are associated with pregnancy outcomes. The objective of this study was to perform metabolomic analyses of sperm from bulls with differing field fertility and evaluate the difference of metabolome profiles. Angus bulls (n = 15) were classified based on a composite field fertility index. Frozen-thawed semen straws (n = 10 per bull) underwent a Percoll gradient sperm purification process. An aliquot of each sample containing 4 million sperm in 100 μl [microliter]. underwent five rounds of freezing/thawing in liquid nitrogen. Metabolomic analysis was performed through ultra- high performance liquid chromatography coupled high resolution mass spectrometry at the University of Tennessee Biological and Small Molecule Mass Spectrometry Core. The GLM procedure of SAS was used to evaluate linear and quadratic relationships between metabolites and CFI. After linear and quadratic analyses, the four highest and lowest fertility bulls were used to evaluate the relationship between fertility class and each metabolite. The MIXED procedure was used with the model including the dependent variable of metabolite, fixed effect of class, and a random statement of date of semen processing and technician. Significance was determined when P ≤ 0.05 and tendency was declared when P ≤ 0.10. A total of 75 metabolites were detected. Quadratic relationships with fertility were observed for kynurenine, xanthine, and ophthalmate (P \u3c 0.05). Tricarballyic acid and creatinine showed a negative linear relationship with fertility (P ≤ 0.05). When differences in metabolite abundance were assessed between the four highest and lowest fertility bulls, N-acetylglutamate and N-acetylglutamine (P ≤ 0.05) had greater abundance in low fertility bulls. Using metabolites as a fertility marker to identify subfertile bulls from a breeding population has promising future implications
RISK ASSESSMENT OF THE NOVEL MINI-SYNPLASTOME AND CONVENTIONAL CHLOROPLAST TRANSFORMATION GENETIC TOOLS IN AGRICULTURE
No full textNovel cutting-edge technologies for plastid genetic engineering have great potential to improve crop traits in agriculture. Genetic engineering of the plastid genome (plastome) can be performed using both conventional homologous recombination (HR) vectors that induce site-specific transgene integration into the plastome, and novel episomal platforms that rely on synthetic plastomes (mini-synplastome) as alternative methods for the expression of transgenes from the backbone of a non-integrating plasmid. Evaluating the risk of both vertical and horizontal gene transfer (HGT) is an important step for the regulatory approval of the environmental release of these novel genetic tools. While plastids are subjected to prevalently maternal inheritance, greatly reducing the risk of transgene escape through pollen, the endosymbiotic origin of plastids from a prokaryotic progenitor may represent a potential risk for HGT to the environmental microbial community. In this study, the naturally competent soil bacterium Acinetobacter baylyi has been used to test the frequency of plant-to-bacterium HGT under laboratory conditions. While plant-to-bacterium HGT can be visualized in vitro as a low frequency event, the mini-synplastome transformation platform does not have an increased risk compared to conventional transformation vectors. After a comprehensive evaluation of risks associated with sequence components of the mini-synplastome (origin of replications and regulatory elements), optimized versions of the mini-synplastome with no residual activity in bacteria have been designed. This study represents a valuable resource for designing transformation platforms for the production of novel synplastomic and marker-free plant varieties with improved environmental biosafety in agriculture
The Fort Pillow Massacre: The American Civil War in Public Memory
No full textWhy did Fort Pillow become the most published racial massacre of the Civil War, and what did it mean for Americans during and after the war? In this paper I examine the development of the memory of the Fort Pillow Massacre as well as its most famous figure, General Nathan Bedford Forrest. The Fort Pillow Massacre was the most publicized racial massacre of the Civil War, during which Confederate soldiers attacked and massacred a Union garrison consisting of Black soldiers and White Tennessee Unionists. The massacre was carried out under the command of Confederate general Nathaniel Bedford Forrest, a figure whose legacy and memorialization remains a subject of controversy. I have researched both the wartime and post-war memory of Fort Pillow and Forrest, and I discuss how Fort Pillow and its widespread coverage intensified wartime violence, especially where African American soldiers were involved. I also discuss how Public memory of General Forrest developed alongside Fort Pillow and was shaped to fit the needs of white southerners in the late 19th and early 20th century. This paper provides insight into the process of Post-Civil War period memorialization and provides a sort of case study for the broad topic of Civil War memorialization from 1864 to 1905. Special attention is given to the development of Forrest’s myth in Memphis, which culminated in the construction of a statue in the General’s likeness in 1905
Municipal E-News: Issue 117: Quarter 3, September 2025
No full textThe Municipal E-News was created by MTAS in 2009 as part of our continuing efforts to meet our mission of providing timely, valuable information and assistance to Tennessee cities
Paradigms of Scientific Machine Learning: From Model-Based Inference in NMR Spectroscopy to Predictive Automation in Agricultural Robotics
No full textData-driven modeling is crucial for extracting insights from complex scientific systems. Modern machine learning provides two powerful but philosophically distinct paradigms: model-based inference, which aims to understand physical mechanisms, and predictive modeling, which optimizes for forecasting accuracy. This dissertation explores and constrast these two paradigms through their application in two different domains: Nuclear Magnetic Resonance spectroscopy (NMR) for biochemical analysis and computer vision for agricultural robotics.
The first section presents two distinct Bayesian inference models I developed to analyze 1D NMR spectra. The first is a nonparametric model which enables robust spectral deconvolution and automatic peak detection of general 1D NMR spectra which we apply to flourine-19 (F), while the second is a parametric model used to quantify the kinetics of chemical exchange. Both models provide not only estimates of spectral parameters but also a rigorous quantification of their associated uncertainty.
The second section focus on a deep learning approach I developed to address the challenge of automated feed monitoring in precision agriculture. I describe a Convolutional Neural Network (CNN) which was trained to accurately predict leftover feed quantities from images; a crucial step in the development of personalized feeding schedules.
Ultimately, these distinct lines of inquiry converge on a central theme: the choice between inferential and predictive modeling is dictated by the scientific objective, whether that objective is achieving deep physical insight or enabling robust automation
Direct Write Editing of Electronic Materials by Gas Assisted Focused Electron Beam Induced Etching for Device Prototyping
No full textFocused electron beam etching (FEBIE) is a direct-write material removal technique that was used with gaseous XeF2 [xenon difluoride] for a chemical assist. FEBIE experiments took place in a scanning electron microscope (SEM) with a gas injection system (GIS) that flowed in XeF2 coincident to the electron beam rastering across the sample surface, leading to etching. In this work, FEBIE was conducted on niobium and WS2 [tungsten disulfide] thin films which are technologically relevant materials for magnetic superconductors and semiconductors, respectively. Atomic force microscopy (AFM) was used to measure the volume etched of box patterns, and SEM images were correlated with Raman spectroscopy to determine the electron dose to clear to the substrate and remove all material within the etch area. Etch rates (etched volume/total time) and etch efficiency (etched volume/charge) were calculated and reported for each material for changes in etching parameters such as electron beam energy, dwell time, current, pixel pitch, and XeF2 pressure. In general, lower beam energy, lower beam current, lower dwell time, and higher XeF2 working chamber pressure increases the etch rates efficiencies. Statistical comparisons of electron and XeF2 flux helped rationalize etch behavior, as well as ab initio molecular dynamics (AIMD) simulations to better understand etching mechanisms. Raman and photoluminescence spectroscopy (PL) were used to probe the damage induced by the FEBIE process. The etching process quenched PL response but was found to be relatively “soft” with respect to the Raman spectra experiencing a slow decrease in intensity for increasing doses without an increasing intensity of the disorder mode. Spontaneous etching was operative for larger pattern areas but had a synergistic effect, increasing etch rate and efficiency. Line etches resulted in etched features with very high resolution at optimized parameters (17 and 21 nm etch widths for niobium and WS2, respectively). Box etches were used to define WS2 flakes into channels of 100 nm widths. Superconducting niobium devices were fabricated and characterized via magnetometry. Josephson junctions were made by etching lines across a 4-point probe channel, and resistive elements were made by etching triangular shapes into the channel
CONSUMERS’ SHIFT TO ONLINE APPAREL RENTING: APPLYING THE PUSH-PULL-MOORING FRAMEWORK
No full textThis dissertation investigates the phenomenon of consumption switching from buying to renting apparel through the lens of the Push-Pull-Mooring (PPM) framework. Four research questions (RQs) guide this inquiry:
RQ1. What are the key push factors associated with negative apparel purchasing experiences that influence switching intention from buying to renting apparel?
RQ2. What are the key pull factors associated with underlying motivation for apparel renting that influence switching intention from buying to renting apparel?
RQ3. What are the key mooring factors associated with both underlying motivation for apparel renting and negative apparel purchasing experiences that influence switching intention from buying to renting apparel?
RQ4. How are the push, pull, and mooring factors associated with switching intentions from buying to renting apparel?
Study 1 addresses RQs 1-3 by exploring online consumer discussions using big data analytics. This study uncovers four push factors (low quality, frustration, dissatisfaction, and overconsumption guilt) regarding apparel buying, four pull factors (hedonic benefits, financial benefits, product variety, and substitutive value) related to renting apparel, and two mooring factors (environmental concerns and mindful consumption) associated with consumers’ personal traitsregarding switching from buying to renting.
Building on Study 1’s findings, Study 2 addresses RQ 4 through a survey design. Switching cost is added as another mooring factor based on the PPM framework literature; switching intention to renting from buying for apparel is examined as the dependent variable. A total of 482 responses were analyzed using Set-Exploratory Structural Equation Modeling (Set-ESEM) to test the seventeen hypotheses. The results indicate that overconsumption guilt from apparel purchasing, hedonic benefits, financial benefits, substitutive value of apparel renting, and consumers’ mindful consumption significantly enhance their switching intention while switching costs exert a negative effect on switching intention. Furthermore, environmental concerns and mindful consumption, but not switching costs, are shown to have moderating effects on the research model.
This dissertation makes meaningful theoretical contributions to the apparel consumption literature by explaining consumer switching from buying to renting based on the PPM framework. It offers practical implications for apparel rental businesses as to how push, pull, and mooring forces can be leveraged to attract consumers
CHARACTERIZATION OF PHAGE INFECTION AND ALGAL INTERACTIONS OF A MODEL ROSEOBACTER GENUS
No full textMobile genetic elements (MGEs) are crucial contributors to bacterial fitness and symbiotic interactions spanning different domains of life. In addition to directly altering host behavior, MGEs, which include plasmids, bacteriophages, and transposases, also influence one another, demonstrated through plasmid replication systems mediating plasmid-incompatibility and plasmid-encoded toxin-antitoxin systems influencing phage resistance. While these interactions and their impacts on host fitness have been well characterized in industrially and medically relevant bacteria, their influence on various environmentally relevant bacteria has only recently been explored. Here, I aim to further our understanding of MGEs on host physiology, fitness, and MGE maintenance in an environmentally relevant system. Previous work on the marine bacterium, Sulfitobacter pontiacus CB2047, demonstrates it encodes four large, low copy plasmids and is readily infected by a suite of isolated bacteriophage. My research identifies interplay between, and characterization of, MGEs while expanding the system to address broader ecological questions. Specifically, this work characterizes several plasmid-mediated phenotypes (e.g., motility, pigment production, LPS modification, sulfite tolerance) that come at the cost of enhanced phage susceptibility, as a temperate phage (φCB2047-A) requires the plasmid-associated LPS profile for successful infection. Additionally, we characterize viral life traits of a lytic phage (φCB2047-B), identifying a phage adsorption target, extended host range, and putative phage defense systems. Lastly, we expanded this model system to include the eukaryotic algae Gephyrocapsa huxleyi. While CB2047 was isolated from an induced G. huxleyi bloom, its potential as an algal symbiont had yet to be assessed. We demonstrate that CB2047, like other S. pontiacus strains, may protect G. huxleyi from specific environmental pathogens. However, as similar algal-roseobacter interactions appear fragile and easily influenced by tertiary microbial parties, it begs the question of how relevant these interactions are in the environment. Collectively, this dissertation characterizes several symbiotic interactions utilizing, primarily, a single roseobacter, setting the foundation for future work. Expansion of these bipartite components to a mesocosm format will assist in determining the relevance and validity of extrapolating laboratory findings to the marine environment