Research and development of Bt rice in Southeast Asia has been overshadowed by the contentious debate over the potential release of transgenic food crops into the region. The study provides empirical evidence on the potential size and distribution of economic benefits of adopting Bt Indica rice in the Philippines and Vietnam through the years 2000 to 2020. Total welfare gains from Bt rice are projected at 618.8 million USD (discounted at 5 percent) and aggregate benefits by region are projected at 269.6 million USD for the Philippines, 329.1 million USD for Vietnam, and 20.1 million USD for the rest of the world. Simulation results indicate that producers in both countries will capture 66.5 percent of the total welfare effect from Bt rice adoption, 25.9 percent will accrue to consumers, 3 percent to the rest of the world, and the loss in Philippine government revenue accounts for 4.6 percent of the total welfare effect. The study also reports how other factors will determine the size and distribution of economic benefits of Bt rice. <i>Vita removed, Sept. 13, 2012, Gmc</i> / Master of Science

The detrimental effects rapid power fluctuation has on wireless narrowband communication channels has long been a concern of the mobile radio community as appropriate channel models seek to gauge link quality. Furthermore, advances in signal processing capabilities and the desire for spectrally efficient and low power radio systems have rekindled the interest for adaptive transmission schemes, hence some method of quickly probing the link quality and/or predicting channel conditions is required. Mathematical distributions for modeling the channel profile seek to estimate fading parameters from a finite number of discrete time samples of signal amplitude. While the statistical inference of such estimators has proven to be robust to rapidly shifting channel conditions, the benefits are quickly realized at the expense of processing complexity. Furthermore, computations of the best-known estimation techniques are often iterative, tedious, and complex. This thesis takes a renewed look at estimating fading parameters for the Nakagami-m, Rice-K, and Weibull distributions, specifically by showing that the need to solve transcendental equations in the estimators can be circumvented through use of polynomial approximation in the least-squared error sense or via asymptotic series expansion which often lead to closed-form and simplified expressions. These new estimators are compared to existing ones, the performances of which are comparable while preserving a lower computational complexity. In addition, the thesis also investigates the impact knowledge of the fading profile has on systems employing adaptive switching modulation schemes by characterizing performance in terms of average bit error rates (BER) and spectral efficiency. A channel undergoing Rice-$K$ fading on top of log-normal shadowing is simulated by correlating samples of received signal amplitude according to the user's doppler speed, carrier frequency, etc. The channel's throughput and BER performances are analyzed using the above estimation techniques and compared to non-estimation assumptions. Further discussion on narrowband fading parameter estimation and its applicability to wireless communication channels is provided. / Master of Science

Roberto Sebastian Matta Echaurren, artista chileno surrealista, se conoce principalmente por su trabajo pictórico. Hoy, con la presente tesis se desea mostrar, explorar, investigar y deducir cómo este artista plástico principalmente pictórico, encuentra en el grabado un camino paralelo en el desarrollo de su obra, un camino bastante desconocido hasta este momento. La tesis que se presenta parte desde los inicios de su vida y relata el transcurso en ella. Ya que todos estos factores históricos y personales son los que nos ayudarán a conocer y comprender quién es Roberto Sebastian Matta Echaurren, un artista que nunca se consideró chileno, un artista universal y un pintor al que nunca se le consideró grabador, a pesar de la cantidad y calidad de su obra gráfica. Estas últimas ideas se expresan y se exponen en profundidad posteriormente dentro de la presente tesis. Luego, la investigación presenta una explicación del por qué es el título "Visiones e influencias de un grabador desconocido" para así poder vislumbrar cómo Matta entiende y vive el arte. Y lo más relevante cómo Matta descubre el grabado, dónde, cómo, cuándo, y por qué desea expresarse en esta área artística. Y se enuncia algo muy relevante que son los reconocidos ¿atelieres¿ de grabado en los que Matta eligió trabajar. Posteriormente se indican los dos atelieres más significativos donde trabajó Matta que son: Atelier George Visat - Albert Dupont y Atelier Fernand Mourlot ¿ Frank Bordas, haciendo un énfasis en la relación de Roberto Matta y Frank Bordas ya que es a partir de esta relación y los datos que nos entregaron las fuentes directas que podremos entender y comprender cómo Matta ve el grabado. Todo lo descrito son las bases que nos guiarán a un segmento esencial de esta tesis que es el capítulo titulado ¿Pintura y Grabado". Dentro de este capítulo veremos la pintura de Matta, su obra finalizada y su proceso dentro de ella. Con el resultado de toda esta información, hacemos un paralelo pictórico y gráfico, siendo lo fundamental establecer y esclarecer si existe o no una relación entre la pintura y el grabado de Roberto Matta. La catalogación de los grabados es el núcleo de la presente tesis, siendo el primer catálogo técnico de la obra de Matta, a pesar de que esta tesis se comenzó hace mas de 5 años, aún no existe un catálogo técnico y razonado completo de su obra. Hoy se presenta un catálogo más completo que los existentes aunque no se posee aún la totalidad de su obra. Posteriormente a la catalogación de sus grabados se presenta un análisis y comentarios para comprender la obra gráfica de este artista, en ella se eligen por grado de relevancia, a nivel histórico, personal o plástico seis obras gráficas, que son: The New School, Hom¿mere, El verbo hommerica, El gran Burundi-burunda ha muerto, Don Q y Ubu Roi. Para finalizar se ha considerado interesante presentar una cronología de la vida y obra de Roberto Matta que estarán unidas a los hechos históricos chilenos y mundiales para darnos un contexto político y social importante que se ve reflejado en las obras plásticas del artista. Deseo mencionar que las ¿Visiones e influencias de un grabador desconocido¿ no es una investigación completa ni acabada, ya que, la finalización de este trabajo fue truncado por una integrante relevante de la familia del artista, no obstante se logra presentar casi un 80% de su trabajo gráfico. Siendo esta tesis el destape hacia esa parte que el artista escondía y protegía como un secreto y de la cual actualmente solo conocemos fragmentos para su comercialización. Posteriormente a la primera revision de la presente tesis por los investigadores externos, se han realizado ciertos cambios, uno es sobre la presentacion del grafico familiar y de la presentacion de las fichas, todos los cambios son a nivel grafico de la presente tesis. Finalmente aquí esta!, se la presento hoy ¿Visiones e influencias para un grabador desconocido¿ un trabajo contra el miedo, contra el olvido, contra el secreto. / Moreno Campos, AG. (2014). Roberto Matta: Visiones e influencias de un grabador desconocido [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36739

The response of plants to environmental stress spans several orders of magnitude in time and space, causing system-wide changes. These changes comprise of both protective responses and adverse reactions in the plant. Stresses like water deficit or drought cause a drastic effect in crop yield, while concomitantly agriculture consumes 1/3rd of the fresh water available to us and there is widespread water scarcity around the world. It is, hence, a fundamental goal of modern biology and applied biotechnology to unravel this complex stress response in laboratory model plants like Arabidopsis and crop models like rice. Such an understanding, especially at the cellular level, will aid in informed engineering of stress tolerance in plants. We have developed and used integrative functional genomics approaches to characterize environmental stress response at various levels of organization including genes, modules and networks in Arabidopsis and rice. We have also applied these methods in problems concerning bioenergy. Since the poor knowledge of the cellular roles of a large portion of plant genes remains a fundamental barrier to using such approaches, we have further explored the problem of 'gene function prediction'. And, finally, as a contribution to the community, we have curated a large mutant resource for the crop model, rice, and established a web resource for exploratory analysis of abiotic stress in this model. All together, this work presents insights into several facets of stress response, offers numerous novel predictions for experimental validation, and provides principled analysis frameworks for systems level analysis of environmental stress response in plants. / Ph. D.

Prior research has concluded that climate change is having an overall negative impact on rice production worldwide. The vast majority of climate change impacts on rice production result from fluctuations in precipitation and temperature, which lead to flooding, water scarcity, and increases in insects and pests, diseases, and weeds. As a small developing country, Guyana is highly vulnerable to climate change despite its insignificant contribution to global warming. Guyana heavily relies on rice cultivation for food, employment, and export earnings. While generally increasing, rice yields have fluctuated over the last two decades. For example, in 2016, rice yields declined by 12.7 percent due to a drought. This dissertation explores the relationship between fluctuating yields and climate change, and how farmers are adapting. Of particular importance are the impacts of climate change on small farmers (those cultivating less than 4.45 hectares or 11 acres) and their ability to successfully adapt. Small farmers are especially vulnerable to a changing climate because they often lack the necessary knowledge, support, and resources to effectively respond and adapt. Given the large percentage of rice farmers engaging in small-scale production in Guyana, this study investigates the impacts of climate variability on rice production and the extent to which the production and productivity of small farmers are affected. It also identifies the coping strategies small farmers employ to combat the effects of climate change and the extent to which these strategies are successful. Given that climate change is expected to vary across different regions of the world, the first aim of this study is to show how the climate in Guyana has changed. At the country level, evidence from descriptive statistics, a linear trend model, and a two-sample t-test shows that minimum and maximum temperatures have increased over the last 111 years. The aggregate data is less clear on changes in precipitation over the last 111 years. However, analysis of farm-level data provides strong evidence of shifts in rainfall patterns. Among 189 small farmers interviewed, 182 (96.3%) perceived changes in rainfall patterns, 170 (89.9%) perceived changes in temperature, 169 (89.4%) perceived changes in extreme weather events, 185 (97.9%) perceived changes in insects and pests, 73 (38.6%) perceived changes in diseases, and 168 (88.9%) perceived changes in weeds. Changes in precipitation have included an increase in intensity and out of season rainfall, which has impacted harvesting due to poor dams, wet fields, and the lodging of plants. The primary responses farmers have adopted include adjusting planting dates based on water availability and the cultivation of different rice varieties. Changes in temperature have resulted in hotter days, accelerating the evaporation of water from fields. In response, farmers replenish water in their fields, when available. Excess rainfall and resulting flooding, drought, and heavy winds have been the primary extreme weather events observed. Excess rainfall and associated flooding submerges, uproots, and/or kills young plants. The lodging of plants due to heavy winds and flooding has been the main impact. In response to flooding, farmers have pumped water out of their fields. There is very little that farmers can do in response to heavy winds. The primary change in insects and pests reported by farmers has been an increase in paddy bug infestations, which cause damage to the grains resulting in lower quality and quantity at harvest. As a result, farmers are engaging in more preventative spraying. An increase in brown spot disease was also reported. Brown spots are primarily found on the leaves, damaging and/or stunting the growth of the plants by reducing the amount of food they manufacture through photosynthesis. Farmers have responded by engaging in preventative spraying and the rotation of fungicides. Increases in red rice and duckweed have been the major changes in weeds observed. Both weeds compete with rice for space, sunlight, nutrients, and water. Additionally, red rice reduces the quality and by extension the price farmers receive. Farmers are responding by spraying more herbicide and using a contact chemical to burn red rice. Multivariate analysis of farm-level data found that land tenure, tractor ownership, membership in an agricultural organization(s), secondary non-agricultural income, and farms located in regions two and four have positive correlations with annual yields. Perceived changes in rainfall, farm size, livestock ownership, participation in rice extension training, and household members help with rice farming were found to have negative correlations with annual yields. Policy recommendations to improve rice production and farmers' resilience include improving research and development capacity; tax exemption for agricultural inputs and equipment; improving extension services; improving the management of irrigation systems and water resources; enhanced access to credit, insurance, and subsidies; improving weather forecasting and climate monitoring; and improving the management of drainage infrastructure. The analytical framework used in this research produced a rich dataset and interesting results that are important to our understanding of farm-level impacts and responses to climate change. As such, it may prove useful for studying climate change impacts in other developing countries that have similar characteristics and face similar risks from climate change as Guyana. / Doctor of Philosophy / The vast majority of climate change impacts on rice production result from variations in rainfall and temperature that lead to flooding, water shortage, and increases in insects and pests, diseases, and weeds. Guyana is highly exposed to climate change. More importantly, the country relies heavily on rice farming for food, employment, and foreign income. Of particular importance are the impacts of climate change on small farmers (growing less than 4.45 hectares) and their ability to successfully adapt. Small farmers are especially helpless because they often lack the necessary knowledge, support, and resources to effectively respond and adapt. Given the large percentage of rice farmers engaged in small-scale production in Guyana, this study explores the impacts of climate variability on rice production and the extent to which the production and output of small farmers are affected. Analysis of farm-level data shows that changes in rainfall have included an increase in intensity and out of season rainfall which has affected harvesting due to poor farm-to market roads, wet fields, and lodging of plants. The main responses involved adjusting planting dates based on water availability and the cultivation of different rice varieties. Changes in temperature resulted in hotter days which increased the loss of water from the field. In response, farmers replenish water in their fields, when available. Excess rainfall and resulting flooding, drought, and heavy winds have been the main extreme weather events observed. Excess rainfall and associated flooding submerges, uproots, and/or kills young plants. The lodging of plants due to heavy winds and flooding has been the main impact. In response to flooding, farmers have pumped water out of their fields. There is very little that farmers can do in response to heavy winds. An increase in paddy bug infestations damaged the grains resulting in lower grain quality while an increase in red rice and duckweed increased the competition for space, sunlight, nutrients, and water. Farmers engaged in more defensive spraying and used a contact chemical to burn red rice.

Casamance is a region in southern Senegal that traditionally produces rainfed rice, but Senegal produces only 1/3 of its rice consumption. Lowland areas, where rice is primarily produced, have acid sulfate soils with low pH and potential aluminum and iron toxicity. The goal of this work was to determine if soil amendments can alleviate soil acidity, counteract the negative biogeochemical effects that occur in flooded conditions, and increase rice yield. A two-year experiment was conducted to test the following soil treatments – agricultural lime, pulverized oyster shell, biochar, and control (no amendment) – in flat and raised beds. Plots amended with lime and shell materials had increased soil pH, base saturation, Ca, and cation exchange capacity. Meanwhile, biochar elevated particulate organic matter and C:N ratios. Exchangeable Fe and Al were negatively correlated with soil pH, while Geobacteraceae populations (Fe reducing bacteria) increased with pH. A greater proportion of the total Fe was strongly bound in fractions that were less bioavailable in plots amended with shell or lime, and overall rice yields were significantly higher following amendment with shell or lime. During the second growing year these effects diminished, suggesting that liming effects did not persist as expected. These results demonstrate the benefits of soil amendments that raise soil pH and suggest that this effect operates by influencing overall soil nutrient availability to rice plants, but further research is needed regarding the timing and sustainability of the beneficial liming effect. / Master of Science

This dissertation addresses the surging global demand for sustainable energy alternatives and biobased products, driven by population growth and the imperative to shift away from finite fossil fuels amidst climate change. The research centers on the catalytic upgrading of rice straw bio-oil, employing bimetallic magnetic nano-catalysts on rice straw-derived biochar to align with the imperative for environmentally conscious energy solutions. In the initial phase, the study systematically explores upgrading processes using varied alcohols, specifically ethanol, and butanol, under mild conditions to enhance bio-oil quality. The detailed evaluation of catalyst composition reveals a notable reduction in oxygen content, coupled with a significant increase in energy density and calorific value. The upgraded bio-oil not only exhibits heightened stability but also undergoes a substantial shift towards a more desirable hydrocarbon-rich composition. The second part of the research optimizes upgrading process parameters catalyst concentration, reaction holding time, and reaction temperature using Response Surface Methodology based on the Box-Behnken experimental design. This optimization refines the catalytic upgrading process, enhancing its efficiency and reliability. Beyond catalytic efficacy, the study considers the magnetic recovery of catalysts for potential reuse, emphasizing sustainability on a broader scale. Set against the backdrop of global energy challenges, this research significantly contributes to advancing the understanding of bimetallic magnetic nano-catalysts. The dissertation unfolds in two parts, with the first segment focusing on Catalytic Upgrading of Rice Straw Bio-Oil via Esterification in Supercritical Ethanol Over Bimetallic Catalyst (CuO-Fe3O4/AcB), involving the variation of Cu and Fe metals on Rice Straw Biochar without hydrogen gas. The exploration continues with the Upgrading of Rice Straw Bio-Oil in Butanol and hydrogen gas Over a Sustainable Magnetic Bimetallic Nano-Catalyst (ZrO2-Fe3O4/AcB). The integrated analytical approach, utilizing XRD, SEM, FT-IR for synthesized catalysts, alongside GC-MS and the Bomb Calorimeter for bio-oil samples, establishes a nuanced understanding crucial for optimizing catalytic performance in sustainable biofuel production.

Human noroviruses (HuNoVs) are the leading cause of viral epidemic acute gastroenteritis and responsible for the deaths of over 200,000 children each year worldwide. HuNoV research has been hampered by the long absence of a readily reproducible cell culture system and a suitable small animal model, while gnotobiotic (Gn) pigs have been a unique animal model for understanding HuNoV pathogenesis and immunity, as well as evaluating vaccine and therapeutics. Recent reports of HuNoVs infection and replication in B cells supplemented with commensal bacteria Enterobacter cloacae and in Blab/c mice deficient in RAG/IL2RG have gained extensive attention, and my studies utilized the well-established Gn pig model to investigate the effects of these two interventions on HuNoV infection. Surprisingly, the colonization of E. cloacae inhibited HuNoV infectivity in Gn pigs, evidenced by the significantly reduced HuNoV shedding in feces and HuNoV titers in intestinal tissues and blood compared to control pigs. Moreover, HuNoV infection of enterocytes but not B cells was observed with or without E. cloacae colonization, indicating B cells were not a target cell type for HuNoV in Gn pigs. On the other hand, using RAG2/IL2RG deficient pigs generated by CRISPR/Cas9 system, with confirmed severe combined immunodeficiency, I evaluated the effects of host immune responses on HuNoV infection. Compared to wild-type Gn pigs, longer HuNoV shedding was observed in RAG2/IL2RG deficient pigs (16 versus 27 days), and higher HuNoV titers were detected in intestinal tissues and contents and in blood, indicating increased and prolonged HuNoV infection in RAG2/IL2RG deficient pigs. In addition, I evaluated dietary interventions including probiotics and rice bran using Gn pig model of HuNoV infection and diarrhea. While the colonization of probiotic bacteria Lactobacillus rhamnosus GG (LGG) and Escherichia coli Nissle 1917 (EcN) in Gn pigs completely inhibited HuNoV fecal shedding, the two cocktail regimens, in which rice bran feeding started either 7 days prior to or 1 day after viral inoculation in the LGG+EcN colonized Gn pigs, exhibited dramatic anti-HuNoV effects, including reduced incidence and shorter duration of diarrhea, as well as shorter duration of virus fecal shedding. The anti-HuNoV effects of the cocktail regimens were associated with the enhanced IFN-𝛾⁺ T cell responses, increased production of intestinal IgA and IgG, and longer villus length. Taken together, my dissertation work improves our understanding of HuNoV infection and immunity, and further supports for Gn pigs as a valuable model for future studies of human enteric virus infection, host immunity, and interventions. / Ph. D. / Human noroviruses (HuNoVs) are the leading cause of viral epidemic acute gastroenteritis. Using the gnotobiotic pig model of HuNoV infection and diarrhea, we found that (1) the colonization of a commensal bacterium E. cloacae inhibited HuNoV infectivity, and B cells were not a target cell type for HuNoV in gnotobiotic pigs. (2) Increased and prolonged HuNoV infection in RAG2/IL2RG deficient pigs, which had severe combined immunodeficiency. (3) The dietary supplementation of rice bran and colonization of two probiotic bacteria significantly reduced HuNoV infectivity and diarrhea, and the beneficial effects were associated with enhanced intestinal immunity and health. Taken together, the dissertation work improves our understanding of HuNoV infection and immunity, and further supports for gnotobiotic pigs as a valuable model for future studies of human enteric virus infection, host immunity, and interventions.

Optimal plant populations are critical in achieving high rice yields. The purpose of this research was to investigate yield penalties associated with inadequate, non-uniform plant populations for modern rice cultivars. Research was conducted at the Delta Research and Extension Center in Stoneville, MS, in 2019, 2020 and 2021. In one study, inbred, herbicide-resistant ‘CL153’ was drill-seeded at 73-18 kg ha-1 after being mixed with inbred, herbicide-susceptible ‘Rex’ at 0-55 kg ha-1. Likewise, hybrid, herbicide-resistant cultivar ‘CL XL7521’ was seeded at 29-8 kg ha-1 mixed with hybrid, herbicide-susceptible ‘XP753’ at 0-21 kg ha-1. At the two- to three- leaf growth stage, imazamox was applied to eliminate ‘Rex’ and ‘XP753’ in their respective studies to achieve the target plant population (TPP). Results indicate that when plant populations are reduced up to 30% in both inbred and hybrid cultivars, grain yields should be comparable if not greater than an adequate, uniform plant population.

The objective of this research was to investigate the occurrence of mycoflora in rice plants and rice seeds in South Africa and their negative impact. A total of six species of Fusarium were isolated from diseased rice plants and rice seeds and identified as F. anthophilum, F. chlamydosporum, F. compactum, F. equiseti, F. fujikuroi and F. semitectum. In the translation elongation factor data set, Fusarium equiseti isolates grouped together within the F. incarnatum - equiseti Species Complex (FIESC). The isolates from rice clustered together in a single clade with the F. equiseti and F. incarnatum isolates forming two separate sub-clades.The isolates of F. equiseti present a new phylogenetically distinct species in FIESC. In the pathogenicity tests, isolates of both F. anthophilum and F. fujikuroi caused bakanae disease to rice plants. Fifty four rice cultivars and lines were tested by the standardized test tube inoculation method for resistance and susceptibility against bakanae isolate of F. anthophilum and the bakanae isolate of F. fujikuroi. None of the rice cultivars and lines was found to be resistant to bakanae isolates of Fusarium spp. The fungicide, benomyl was found to be most effective as a seed treatment for controlling bakanae disease of rice due to isolates of both F. anthophilum and F. fujikuroi. Thiram was found to be the least effective fungicide for controlling bakanae disease of rice caused by isolates of both the Fusarium spp. Apart from Fusarium species, other fungi that were also isolated from diseased rice plants and rice seeds were identified as Alternaria alternata, Alternaria longipes, Cochliobolus miyabeanus, Nigrospora sphaerica, Phoma eupyrena, Phoma jolyana, Phoma sorghina and Pithomyces sp. In mycotoxin tests, the isolates of both F. anthophilum and F. fujikuroi produced moniliformin. None of the isolates of F. anthophilum and F. fujikuroi produced fumonisins. This research is important as it identifies many fungal species in rice plants and seeds in South Africa for the first time. Currently, there is very little literature that makes reference to such findings under South African conditions. In addition, this investigation unravels previously unknown information on the resistance of rice to bakanese disease. Finally, information is provided on the effectiveness of commonly used fungicides (benomyl and thiram) to control rice diseases. This knowledge is crucial information that is useful to plant pathologists, the farming community and the scientists that are involved in strategies of fighting or reducing rice diseases so as to help contribute to food security. / Environmental Sciences / D. Phil. (Environmental Science)