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Quantifying Tradeoffs Among Water Use, Energy Use, Yield and Environmental Impact for Various Levels of Irrigation and Nitrogen Fertilization of Grain Sorghum
No full textCrop production systems are the most complex systems, which have many interlinkages among different sectors. Identifying and quantifying tradeoffs among those interlinkages is important to enhance the sustainability of crop production. This study aims to use water-energy-food (WEF) nexus approach to quantify tradeoffs among water use, energy use, food production, economic return and environmental impact to identify the optimum levels of irrigation and nitrogen (N) fertilization for grain sorghum production in the southeast region of Texas. The field experiment was conducted at the research farm of Prairie View A&M University in 2023. Four irrigation levels (rainfed and three levels of crop evapotranspiration including 75%, 100% and 125%) and four N fertilizer applications (recommended level, half recommended, double recommended and zero) were selected as treatments. Water use efficiency, yield, energy productivity, net income and carbon footprint were selected as indicators to represent interlinkages among different sectors and estimated for 16 different levels of irrigation and N fertilizer application combinations. WEF nexus index was developed using the above five selected indicators and the treatment with the highest WEF nexus index was selected as optimum combination. Among 16 treatments, in rainfed conditions and at 75% ET irrigation level, yield was low, and the cost of production was high with a negative net income. Highest yield, water use efficiency and carbon footprint were observed in the 100% ET with double recommended N fertilizer application while highest energy productivity and net income were observed at the 100% ET with half recommended N fertilizer application. Application of irrigation water at 100% of crop evapotranspiration and half recommended N fertilizer (90 kg of N/ha) resulted in the highest WEF nexus index value, which is 0.812 and was hence selected as optimum levels for grain sorghum to enhance the sustainable production. The findings of this study highlight the importance of quantifying tradeoffs among water-energy and food production and applying holistic tool such as WEF nexus index to make decisions on selecting appropriate crop management practices to ensure the sustainable use of water and energy in crop production while achieving optimum productivity
Quantifying Complex Grazing Management Practices and Producer Systems Thinking Skills
No full textThe capacity of alternative grazing management strategies to maintain or enhance the production of ecosystem services and ranch profitability continues to be vigorously debated. However, the parameters used to differentiate among alternative grazing systems are inadequate, and standardized methods for comprehensively characterizing grazing systems are lacking. Inconsistent approaches to, and definitions of, adaptive management have likely contributed to the inconsistent findings in grazing management research. Systems thinking has been promoted to enhance decision making in complex natural resource systems but there is a lack of research evaluating the relationship between adaptive management implementation and systems thinking skills. This dissertation (1) develops a rigorous weighted composite index to serve as a standardized approach for more accurately classifying the grazing intensity implemented in grazing management systems; (2) develops an instrument that thoroughly measures the implementation of adaptive management at the ranch level, and; (3) tests the hypothesis that the level of adaptive management is positively associated with a producer���s level of systems thinking skills. The Grazing Intensity Index (GII) characterizes grazing systems differently than characterization efforts that rely on only a few descriptors, which suggests that the GII more objectively and comprehensively captures the cumulative effect of the spatiotemporal distribution of grazing and rest within a grazing system. The Adaptive Management Index (AMI) is positively correlated with perceptions of increased connectedness between grazing system elements, which suggests that the AMI effectively measures the implementation of adaptive management in livestock grazing systems. Gross livestock sales and gender, rather than the AMI, are primary drivers of systems thinking as measured by the systems thinking skills instrument, suggesting that producers who generate a larger volume of sales from their operation have a greater tendency for viewing systems holistically. Implementing the GII and AMI in future grazing management research studies will enable researchers to more precisely characterize contrasting grazing management strategies resulting in more robust findings and enhanced communication among researchers, and between researchers, extension personnel, and producers. Additional research is needed to evaluate the relationship between adaptive management implementation and systems thinking skills
De-Equivariantization in Fusion Categories from Quantum Groups at Roots of Unity
No full textThe representations of quantum groups at roots of unity lead to an important class of premodular tensor categories. We will discuss the construction and important properties of these categories. Then we will consider the categories of this kind associated to type D Lie Algebras and present explicit computations to demonstrate the fusion rules, grading and pointed subcategory. We will also discuss and provide examples of de-equivariantization. This process involves creating a new category by taking the category of modules over an algebra object, in some sense taking a ���quotient��� based on the tensor product with this object. More specifically, we identify a subcategory equivalent to Rep(G) for some finite group G and take the algebra object of functions on G in this subcategory. Then we take the modules over this algebra object in the centralizer of Rep(G), which ensures that the resulting category of modules retains the structure of a braided fusion category. Examples of de-equivariantization in the literature primarily consist of performing de-equivariantization with a cyclic group G. We provide an example of de-equivariantization by a non-cyclic group Z2 �� Z2 and discuss strategies to approach de-equivariantization by non-cyclic groups. Specifically, we show that the boson condensation of C(so(8), 10, q) by the full pointed subcategory Rep(Z2��Z2) is isomorphic to four copies of the integral subcategory of C(su(2), 5, q)
Improving Access to River Discharge Data Through Satellite Remote Sensing
No full textRivers are a critical engine for the transportation of water, nutrients, and sediments across landscapes, making them an integral natural resource for many ecosystems and civilizations. Historically, river discharge, the volumetric flow of water at a point, has been measured using river gauges. These gauge discharge measurements serve a vital role in water resource management by improving our understanding of river dynamics and informing flood predictions. In this dissertation, I compile the largest collection of publicly available river gauge data and analyze this database for spatial and temporal trends in river gauge availability. I find that global gauge availability has remained stable since 1980 but the gauge network is biased towards the Americas and Europe. In addition, I find that 77% of global gauge records are not available in real-time, limiting our ability to make effective water management decisions. To alleviate the issues associated with the global gauge network, I leverage satellite remote sensing to provide real-time estimates of discharge in both gauged and ungauged reaches. By developing empirical relationships between gauge discharge measurements and satellite river widths, I am able to add nearly 300 thousand daily discharge observations to the global gauge record. Along ungauged North American reaches, I develop an algorithm, RODEO, to estimate river discharge efficiently and accurately from Landsat imagery. RODEO is available as a publicly available Google Earth Engine application and provides a path forward for the accurate quantification of remote sensing of discharge uncertainty. River discharge can directly influence and be influenced by lake dynamics. With the aim of better understanding lakes and rivers as an interconnected system, I develop the LakeFlow algorithm. LakeFlow leverages satellite observations from the recently launched Surface Water and Ocean Topography (SWOT) mission and mass conservation principles to estimate discharge at river-lake boundaries. LakeFlow has been tested using synthetic datasets at three lakes and shows promising accuracy. Ultimately, LakeFlow can be used to provide discharge at approximately 35 thousand river reaches globally
The Effect of Mechanical Degradation on Sustained Fluoride-Releasing O-Rings: An In-Vitro Study
No full textTraditional methods for caries prevention focus on operator application or patient compliance, but the current study aims to establish a viable alternative to the current white spot lesion prevention techniques. O-rings incorporated with fluoride have been previously studied and assessed for a continuous release of fluoride, however, their ability to release fluoride after being mechanical degraded has not been assessed. The proposed research will provide more evidence on the efficacy of the O-rings and their ability to withstand mechanical degradation.
To assess the mechanical degradation these CaF��� O-rings they were brushed in a toothbrushing simulator for 2-weeks and 8-weeks in DIW at a force of 225g. Control and brushed calcium fluoride O-rings were placed on upper lateral incisor brackets, brushed, weighed, and soaked in distilled water. The amount of released fluoride was tested over a period of 7 weeks.
There were statistically significant differences between the control group and the 2-week and 8-week brushing groups throughout the entire duration of the study. The control and experimental groups dropped below the therapeutic range after the first week. When comparing the control group and experimental groups we see there were statistically significant difference between control and 2-week as well as control and 8-week groups at all time points in the study. All three groups experienced a tapering off of fluoride release. When looking at the cumulative release, the control group showed a statistically significant larger cumulative release of fluoride rate compared to both the 2- and 8-week groups (p<0.001). Weight analysis showed that there is a significant loss of material after mechanical abrasion when compared to before brushing. Additionally, there were several revisions to the protocol that were necessary to produce consistent results.
The 2-week and 8-week groups showed significantly less fluoride release over the duration of the study and had lower release rates when compared to the control, which can be affected by the coating protocol. In the first week of experimentation the 2-week group had a higher release rate, but this difference did not continue for the duration of the study
Improving the Accuracy, Reliability, and Throughput of Nanoindentation Hardness and Modulus
No full textInstrumented nanoindentation is a form of load and depth sensing indentation that characterizes material properties on the micro- and nanoscale. This form of indentation is widely used for its ability to measure a variety of material properties on very small scales in a high-throughput manner without extensive sample preparation and with minimal sample damage after testing. However, this versatility introduces a level of complexity, and due to the various methods for performing nanoindentation tests and collecting data, there are inevitably opportunities to encounter and cause experimental errors. Common sources of error include not accounting for pile-up or other area-related issues, frame stiffness and sample mounting issues, and using improper sample preparation and testing parameters as well as testing non-ideal samples. This thesis provides a background for these sources of error and expands on best practices from research and literature to overcome or avoid these sources of error. To this end, a highly ordered pyrolytic graphite sample was tested and the lack of residual indent impression and sample anisotropy was examined in detail, with methods used to account for such sample non-idealities and provide more reliable data presented. This thesis further investigates how sample mounting conditions affect and can sometimes produce error in the compliance of the nanoindentation system. Such research expands and improves the minimal research that currently exists in the literature by providing concrete methods for avoiding issues caused by sample mounting in order to produce accurate and reliable data
The BAZ Family of Chromatin Remodelers in Colorectal Cancer: Insights into Oncogenesis, Alternative Splicing and Chemosensitization
No full textColorectal cancer (CRC) poses a significant healthcare challenge worldwide, necessitating a deeper understanding of the molecular mechanisms underlying its pathogenesis for improved therapeutic interventions. This thesis investigates the BAZ (Bromodomain Adjacent to Zinc finger) family of chromatin remodelers and their intricate involvement in CRC. The BAZ family members, including BAZ1A, BAZ1B, BAZ2A, and BAZ2B, exert critical regulatory functions in chromatin architecture and transcription, impacting various cellular processes from development to disease.
In colorectal cancer, BAZ1A is overexpressed, and its depletion resulted in diminished cell viability, increased apoptosis, augmented DNA damage, and cellular senescence, concomitant with the downregulation of components within the Wnt/��-catenin signaling pathway. In vivo studies corroborated these findings, revealing that knockdown of BAZ1A leads to diminished tumor growth and alterations in chromatin regulation. Interestingly, BAZ1A undergoes alternative splicing, which is promoted by treatment with histone deacetylase inhibitors, thereby highlighting its therapeutic potential. Remarkably, the full-length form of BAZ1A is implicated in DNA repair mechanisms, while its alternatively spliced counterpart is susceptible to increased DNA damage and sensitivity to DNA-damaging agents. These observations underscored the oncogenic role of BAZ1A in colorectal cancer and the importance of considering an oncogene���s alternative splicing patterns.
Similar to BAZ1A, BAZ2A is also upregulated in CRC and associated with reduced patient survival. Functional studies demonstrated their roles in inhibiting cell viability, colony formation, and modulating Wnt/��-catenin signaling. Inhibition of BAZ2A led to reduced tumor growth rates in mouse models, where it also affected histone modification patterns, favoring a less repressive chromatin state, and influencing major histocompatibility complex (MHC) regulation.
In contrast to BAZ1A and BAZ2A, BAZ1B knockdown enhanced cell viability, colony formation, and altered cell cycle progression, suggesting a tumor-suppressive role in metastatic CRC. BAZ1B impacted c-MYC expression independently of the Wnt/��-catenin pathway, and influenced p53 and p21 levels, implicating its involvement in tumor suppressive pathways.
Overall, the study underscores the potential of BAZ family members as therapeutic targets in CRC. Future research should focus on elucidating their molecular mechanisms, translating findings into clinical applications, and exploring combination therapies to improve treatment outcomes for CRC patients, thus advancing more personalized therapeutic approaches for CRC
The BAZ Family of Chromatin Remodelers in Colorectal Cancer: Insights into Oncogenesis, Alternative Splicing and Chemosensitization
No full textColorectal cancer (CRC) poses a significant healthcare challenge worldwide, necessitating a deeper understanding of the molecular mechanisms underlying its pathogenesis for improved therapeutic interventions. This thesis investigates the BAZ (Bromodomain Adjacent to Zinc finger) family of chromatin remodelers and their intricate involvement in CRC. The BAZ family members, including BAZ1A, BAZ1B, BAZ2A, and BAZ2B, exert critical regulatory functions in chromatin architecture and transcription, impacting various cellular processes from development to disease.
In colorectal cancer, BAZ1A is overexpressed, and its depletion resulted in diminished cell viability, increased apoptosis, augmented DNA damage, and cellular senescence, concomitant with the downregulation of components within the Wnt/��-catenin signaling pathway. In vivo studies corroborated these findings, revealing that knockdown of BAZ1A leads to diminished tumor growth and alterations in chromatin regulation. Interestingly, BAZ1A undergoes alternative splicing, which is promoted by treatment with histone deacetylase inhibitors, thereby highlighting its therapeutic potential. Remarkably, the full-length form of BAZ1A is implicated in DNA repair mechanisms, while its alternatively spliced counterpart is susceptible to increased DNA damage and sensitivity to DNA-damaging agents. These observations underscored the oncogenic role of BAZ1A in colorectal cancer and the importance of considering an oncogene���s alternative splicing patterns.
Similar to BAZ1A, BAZ2A is also upregulated in CRC and associated with reduced patient survival. Functional studies demonstrated their roles in inhibiting cell viability, colony formation, and modulating Wnt/��-catenin signaling. Inhibition of BAZ2A led to reduced tumor growth rates in mouse models, where it also affected histone modification patterns, favoring a less repressive chromatin state, and influencing major histocompatibility complex (MHC) regulation.
In contrast to BAZ1A and BAZ2A, BAZ1B knockdown enhanced cell viability, colony formation, and altered cell cycle progression, suggesting a tumor-suppressive role in metastatic CRC. BAZ1B impacted c-MYC expression independently of the Wnt/��-catenin pathway, and influenced p53 and p21 levels, implicating its involvement in tumor suppressive pathways.
Overall, the study underscores the potential of BAZ family members as therapeutic targets in CRC. Future research should focus on elucidating their molecular mechanisms, translating findings into clinical applications, and exploring combination therapies to improve treatment outcomes for CRC patients, thus advancing more personalized therapeutic approaches for CRC
The BAZ Family of Chromatin Remodelers in Colorectal Cancer: Insights into Oncogenesis, Alternative Splicing and Chemosensitization
No full textColorectal cancer (CRC) poses a significant healthcare challenge worldwide, necessitating a deeper understanding of the molecular mechanisms underlying its pathogenesis for improved therapeutic interventions. This thesis investigates the BAZ (Bromodomain Adjacent to Zinc finger) family of chromatin remodelers and their intricate involvement in CRC. The BAZ family members, including BAZ1A, BAZ1B, BAZ2A, and BAZ2B, exert critical regulatory functions in chromatin architecture and transcription, impacting various cellular processes from development to disease.
In colorectal cancer, BAZ1A is overexpressed, and its depletion resulted in diminished cell viability, increased apoptosis, augmented DNA damage, and cellular senescence, concomitant with the downregulation of components within the Wnt/��-catenin signaling pathway. In vivo studies corroborated these findings, revealing that knockdown of BAZ1A leads to diminished tumor growth and alterations in chromatin regulation. Interestingly, BAZ1A undergoes alternative splicing, which is promoted by treatment with histone deacetylase inhibitors, thereby highlighting its therapeutic potential. Remarkably, the full-length form of BAZ1A is implicated in DNA repair mechanisms, while its alternatively spliced counterpart is susceptible to increased DNA damage and sensitivity to DNA-damaging agents. These observations underscored the oncogenic role of BAZ1A in colorectal cancer and the importance of considering an oncogene���s alternative splicing patterns.
Similar to BAZ1A, BAZ2A is also upregulated in CRC and associated with reduced patient survival. Functional studies demonstrated their roles in inhibiting cell viability, colony formation, and modulating Wnt/��-catenin signaling. Inhibition of BAZ2A led to reduced tumor growth rates in mouse models, where it also affected histone modification patterns, favoring a less repressive chromatin state, and influencing major histocompatibility complex (MHC) regulation.
In contrast to BAZ1A and BAZ2A, BAZ1B knockdown enhanced cell viability, colony formation, and altered cell cycle progression, suggesting a tumor-suppressive role in metastatic CRC. BAZ1B impacted c-MYC expression independently of the Wnt/��-catenin pathway, and influenced p53 and p21 levels, implicating its involvement in tumor suppressive pathways.
Overall, the study underscores the potential of BAZ family members as therapeutic targets in CRC. Future research should focus on elucidating their molecular mechanisms, translating findings into clinical applications, and exploring combination therapies to improve treatment outcomes for CRC patients, thus advancing more personalized therapeutic approaches for CRC
Nature of Science in Science Education: Establishing Common Ground
No full textA deep and robust understanding of the nature of science (NOS) has been increasingly recognized as a core component of any form of meaningful scientific literacy. However, little progress has been made with NOS teaching and learning over the past century. This has become an increasingly problematic situation as citizens have struggled with numerous high-profile socioscientific issues over the past several decades (e.g., climate change). Unfortunately, scholars��� discordant approaches to NOS in science education have created an acrimonious environment that has likely impeded efforts to promote attention to NOS teaching and learning. This problematic state of affairs is exacerbated by a lack of clarity regarding the specific ways that NOS understanding affects SSI decision-making, and a dearth of quantitative instruments that can provide valid and reliable inferences about respondents��� understanding of NOS constructs. This dissertation research contributes to the improvement of NOS teaching, learning, and research by: (1) Identifying the major themes that exist within the NOS approach literature, along with the areas of agreement and disagreement related to each theme; (2) Determining the NOS constructs related to climate change beliefs and attitudes; and (3) Creating a novel, high-resolution, quantitative NOS instrument that targets a specific NOS construct (i.e., methodological pluralism). The thematic analysis of NOS approach literature yielded seven central themes that contained numerous areas of agreement and disagreement that can help to provide order to future scholarly discussions. The examination of NOS connections to climate change beliefs and attitudes within the literature identified 15 relevant NOS constructs that provide an important focal point for science educators, communicators, and researchers. Instrument development efforts resulted in a tool that can provide high-resolution, valid, and reliable inferences about students��� views regarding methodological pluralism. While further refinement of the instrument is needed, this work represents a significant advance in quantitative NOS assessment. Collectively, the research related to this dissertation has addressed several important gaps in the field of NOS education, and establishes an important future line of research