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Two Essays on Agricultural Trade Policy and Total Factor Productivity
No full textThis dissertation consists of two essays: the first examines the welfare and trade implications of the 2016–2017 drought in Brazil and the subsequent temporary import ban on Robusta coffee; the second examines how trade openness influences agricultural total factor productivity across 26 NUTS-2 regions in Türkiye from 2013 to 2020.
The first essay focuses on Brazil, a major Robusta coffee producer and exporter that faced a significant drought in 2016–17, reducing Robusta output. In response, the government initially allowed one million 60-kg bags of Robusta coffee to be imported. An import ban was imposed shortly afterward due to lobbying by domestic Robusta farmers. Findings indicate that the import ban improved Brazilian Robusta producers’ welfare by 280.26 million, nearly offsetting the drought’s adverse effects. However, it increased unit cost for Brazilian soluble processors by 10% and reduced consumer surplus in Brazil by 174.44 million. Major Robusta exporters faced reduced exports to Brazil and up to 9% lower prices, losing 0.3363 to 0.7564 million 60-kg bags. Additionally, foreign consumers of Brazilian soluble coffee lost 107 million in welfare from higher prices. Without the import ban, global stakeholders would have seen a $12.61/bag higher world bean price.
The second essay employs a translog stochastic frontier model with monotonicity constraints, it decomposes TFP growth into technical change and efficiency change across 26 NUTS-2 regions over 2013–2020. It also examines the relationship between technical efficiency and trade openness by integrating regional agricultural trade openness into the model as an (in)efficiency driver. Additionally, it explicitly controls for climatic effects, including average temperature and precipitation in the frontier. Results highlight pronounced regional disparities, with export-oriented regions exhibiting higher efficiency. Moreover, trade openness is significantly and positively associated with technical efficiency. Moderate temperature and rainfall positively affect agricultural output, while extreme conditions negatively impact yields. TFP growth is predominantly driven by technical change, while efficiency change slightly detracts from overall productivity gains.
Advisors: John Beghin and Lilyan Fulginit
Global, Continental, and Local Scale Paleoenvironmental Reconstruction Methods for Interpreting the History of Miocene North America and the Great Plains
No full textThe Miocene of North America is characterized by dynamic changes in herbivore communities, habitat composition, and global climate. Long-term cooling and drying trends influenced large changes in floral and faunal communities. The Great Plains, North America shifted from closed-canopy biomes to open-canopy biomes with C3-grasses to biomes with C4-grasses. This shift affected the herbivore communities as browsing-adapted ungulates were replaced by grazing-adapted ungulates. Much focus has centered on the Great Plains, so it is not well understood how the changes in biomes compare to other regions of North America. The models used for vegetation density indicate open-canopy biomes since at least the early Miocene, but open canopy biomes include a range of modern analogs and other environmental interactions are not well understood. Also, the early investigations of herbivore community changes were performed with proxies that are now known to not be true representations of diet.
First, I compile a large dataset of stable carbon isotopes from Miocene herbivores across North America and apply a predictive vegetation density model to examine how biomes in different regions change throughout the Miocene. The shift to open-canopy biomes across North America was asynchronous and each region experienced the incorporation of C4-grasses into the environment and herbivore diets differently due to regional climatic differences.
Second, I reexamine the predictive vegetation density model by comparing bulk stable carbon isotopes of various global biomes to remotely sensed, satellite-derived vegetation indices. Bulk stable carbon isotopes follow the same trends for sunlight and water availability as do vegetation indices used as proxies for vegetation density, productivity, etc. and can be used to predict biome characteristics in more detail than previously thought.
Lastly, I revisit herbivore community changes through the Miocene of Nebraska, USA by investigating dietary guild ratios assigned by a combined mesowear-score and hypsodonty-index method. Hypsodonty is still a useful proxy in understanding community dietary changes and browsing taxa in the Miocene may have been more flexible in their diets than previously thought possible. Browse-rich habitats were still abundant despite open-canopy biomes dominating the Miocene of Nebraska.
Advisor: Peter Wagne
Exploring the Landscape of Collective Leadership Practice in Rural Nebraska: A Qualitative Sequential Multimethod Study
No full textRural communities across Nebraska face a myriad of complex challenges that cannot be solved by individual, heroic leaders. As such, collective leadership has begun to emerge in these communities as actors coalesce around local issues. However, little is known about collective leadership practice and development in rural contexts, resulting in a theory-to-practice gap. To that end, this qualitative sequential multimethod study sought to explore how rural community leaders and community development educators perceive, describe, and make meaning of collective leadership practices in rural Nebraska. Three phases comprise this study.
Phase I, the QUAL phase, was guided by the question, How do rural community leaders in Nebraska experience collective leadership in their communities? This phase leveraged transcendental phenomenology to deeply explore how rural community leaders experience collective leadership in their communities through conducting one-on-one interviews. Three overarching themes and eight subthemes were discovered in the Phase I data: (a) structures, practices, and behaviors of collective leadership (subthemes: importance of communication; community engagement, input, and dialogue; context-specific mindsets and approaches); (b) facilitators and supports of collective leadership (subthemes: relationships and partnerships, leveraging external expertise and resources, the power of invitation); and (c) barriers and tensions in collective leadership (subthemes: leader burnout, navigating resistance to change).
Phase II, the qual phase, was guided by the question, What insights, reactions, and perspectives do RPN educators have regarding how community leaders experience collective leadership? This phase presented the Phase I findings to Rural Prosperity Nebraska (RPN) educators and invited their perspectives and reactions in a focus group setting, using a thematic analysis approach for data analysis. Three themes emerged from the Phase II data: (a) collective leadership as a deep cultural (not just structural) shift; (b) organic emergence of collective leadership); and (c) community coaching, mentoring, and peer learning mechanisms.
Phase III involved synthesizing the Phase I and Phase II findings and depicting the integrated findings in a visual joint display, and was guided by the question, How do the Phase II (qual) findings connect to the Phase I (QUAL) findings? The synthesis and joint display offered in this phase helps to demonstrate the ways in which the findings of Phase I and Phase II connect to and crystallize each other.
This study contributes to collective leadership scholarship by deepening empirical understanding of how collective leadership is experienced and perceived by rural community leaders in Nebraska. Further, this study advances community development scholarship by offering a practice-informed exploration of what is required to deepen capacity for ongoing collective leadership work in rural Nebraska. The integrated findings of this study may be of interest to leadership scholars, rural community leaders, and community developers.
Advisor: Lindsay J. Hasting
Screening for Chloroplast Inner Envelope-thylakoid Membrane Contact Site Proteins
No full textMost life on Earth is dependent upon the capture of solar energy and subsequent fixation of carbon. In members of the Archaeplastida lineage these biological processes take place in semi-autonomous organelles called chloroplasts. Chloroplasts are bounded by a double membrane envelope and contain the photosynthetic membrane system, thylakoid membranes, where light capture takes place. While a great deal is known about how thylakoid lipids are synthesized and protein complexes therein are properly maintained, very little is known regarding the processes by which lipids are transported to thylakoids which lack de novo glycerolipid synthesis. We have worked to identify candidate proteins which could be involved in chloroplast lipid trafficking, particularly at membrane contact sites. Chapter 1 will provide an overview of photosynthetic lipid synthesis and trafficking to the chloroplast envelopes. This includes the biosynthesis of glycerolipids and the movement of lipids between the various membranes where they are made. Chapter 2 is an investigation of select candidate proteins which were selected as potential components of chloroplast lipid trafficking. This chapter is a combination two orthologous approaches; one which was based on homology and targeting prediction, the second which is based on isolation of membrane contact site enriched membrane fractions. Four candidates were identified by overlap with chlorophyll autofluorescence, two were identified by fractionation, and one protein was selected for cloning and further study based its likely role in chloroplast membrane contact sites.
Advisor: Rebecca L. Rosto
The Advancement of Automation in Beef Packaging Pack-off Systems
No full textMarble Technologies has developed a new system for beef, pork, and lamb producers that improves quality and worker experience in the packing of products. This work explores the augmentation of this system with the introduction of robotic packing to further reduce labor, increasing worker availability for value-added tasks.
Experimentation conducted to date has explored handling delicate meat products in the standard Marble system and the proposed robotic systems. These mechanical subsystems are critical intermediaries in safely and reliably delivering products to robots and from robots to boxes. Two case studies are presented to walk through the process and challenges of integrating robotics into the existing systems. These case studies include an in-depth simulation of both the existing system and the proposed robotic systems, while also proposing modifications to control algorithms to improve productivity. The studies present methods for measuring packer and robot productivity to direct the development of system layouts. Finally, custom robotic concepts are presented as alternatives to commercially available robotic solutions. As a result of this work, it is proposed that the engineering challenges to the viability of a robotic packing solution have been met and that robotic meat packing is deemed viable. Additionally, while routes forward in the development of the system are presented, much engineering effort remains to bring a robotic solution to market.
Advisor: Carl Nelso
Intergenerational Family Dynamics among Caregivers and Children’s Social-Emotional Development in China
No full textThe early years of a child’s life are pivotal for social-emotional development. While extensive research has explored the role of family settings in fostering children\u27s social-emotional development (Bornstein, 2005), the impact of grandparental involvement, particularly the caregiving dynamics between generations, remains less well understood. This study aims to fill this gap by examining two critical aspects of intergenerational dynamics among caregivers (i.e. parent-grandparent coparenting and parent-grandparent relationship quality) and their associations with children’s social-emotional development (i.e. social skills and problem behaviors). Two specific aims were delineated: 1) examine the unique contribution of parent-grandparent coparenting, especially the power and authority domain (i.e. power process and power outcome), to child social-emotional development; and 2) examine the unique contribution of parent-grandparent relationship quality to child social-emotional development. The study used cross-sectional survey data collected from 286 parent-grandparent dyads with children aged 3 to 6 years in China and used path analysis to achieve the research aims.
Four key findings emerged. For intergenerational coparenting, 1) grandparent-reported intergenerational coparenting, particularly the power outcome dimension, which represented the extent to which grandparents felt their perceptions were acknowledged and integrated in childrearing decisions, was significantly associated with lower levels of child problem behaviors; 2) parent-reported intergenerational coparenting did not show any significant, unique contribution to child social-emotional development. Regarding intergenerational relationship quality, 1) parent-reported intergenerational relationship quality was significantly and positively associated with children’s social skills; 2) grandparent-reported intergenerational relationship quality did not significantly predict either child social skills or problem behaviors. Situated within the cultural and structural context of China, where grandparental involvement is both normative and substantial, this study highlights the importance of moving beyond parent-focused models of caregiving. The results also offer critical insight into the differentiated roles of parents and grandparents in shaping children’s outcomes.
Advisor: Gilbert R. Parr
Flooding: Risk Assessment and Its Interaction with Population & Environmental Health
No full textFlood events have significant implications for both population and environmental health. This dissertation aims to explore flood risk and its interaction with humans and the environment. The key questions addressed in this dissertation include improving the existing flood risk framework to better assess population vulnerability and associated risk. Additionally, it explores how interactions among risk components vary across spatial scales and regions, and how these variations influence overall flood risk. The dissertation also investigates how to design a vulnerability component specific to flooding within flood risk estimation. Finally, it answers whether flood-specific vulnerability differs for a population compared to vulnerability from other natural disasters. In the context of environmental health, this research examines the potential of different agricultural conservation practices (ACPs), such as cover crops, tillage management schemes, crop rotation strategies, and filter strips, in reducing peak runoff and enhancing water quality (sediment transport and nutrients). The dissertation also attempts to identify the trends in ACPs, followed by identifying the causal relationships among the atmospheric variables, water quantity and quality indicators, and the implementation of agricultural conservation.
Advisor: Tirthankar Ro
On Kernels and Antiderivatives of Nonlocal Derivatives
No full textNonlocal operators are mathematical operators taking functions to other functions f → Df , where to evaluate the operator Df at a point x, one must know the value of f in some region around x, and that region cannot be arbitrarily small. Nonlocal derivatives are like derivatives in that they measure the deviation of a function f(z) from f(x) when z is close to x. In this thesis, we will study nonlocal operators of the form
Dkf(x) = [integral]Ω [f(x) - f(z)]k(x,z)dz
In the first part of the thesis, we will discuss solutions to equations of the form Dk(f) = g (i.e. “nonlocal antiderivatives” of a function g). We will prove existence and uniqueness, and show how to approximate said solutions. In the second, we will present results about the kernels of nonlocal operators and maximum principles for solutions to Dkf ≤ 0, and show that under various circumstances, the only functions with Dkf = 0 are constant.
Advisor: Mikil Fos
The Tree That Would Not Fall: An Educator’s Autoethnographic Journey of Healing Through Words
No full textTo say the world has changed since the 2020 COVID-19 shut down is to minimize the micro and macro social changes that infiltrated the school system. In the wake of it all, we find a landscape marred by a both rising teacher attrition and struggling student motivation. This autoethnographic dissertation explores the deeply personal experience tethered to a deeply problematic system that contributes to not only teacher burnout but what I came to know as teacher demoralization. Personal traumas of teachers profoundly impact their experience in the classroom, and as I examined my own near departure from the classroom, I came to journey back to the by finding purpose and joy once more. Reflective and creative strategies such as autoethnography and poetic inquire afford teachers like me an intimate opportunity to explore how my personal trauma, emotional labor, and professional identity intersected but also how their roots affected me as a professional. Using a metaphor of a tree, this work investigates how experiences outside the classroom directly affect what happens within in. Rather than documenting burnout and studying numbers, this study aimed to rehumanize the educator voice and offer insight into how a creative expression can serve as a tool to heal, understand, and ultimately, transform. The findings suggest that through systemic awareness and changes designed to center educator voice, we could create a space where educators feel seen, heard, and valued, especially when educators are seen as professionals and valued as masters of their craft. Ultimately, this dissertation contributes to broader conversations about teacher resilience, trauma-informed practice, and the urgent need to support educators through reflective, research-based approaches.
Advisor: Lauren Gatt
Modifying Italian Consonants in the Voice Studio: An Exploratory Sequential Mixed Methods Study
No full textThe body of lyric diction literature, particularly on Italian, has grown substantially in the second half of the twentieth century. Lyric diction courses are now a required part of many voice programs across the United States. The widespread use of International Phonetic Alphabet (IPA) transcriptions and transcription rules has significantly contributed to the field. However, relatively few sources focus on the pedagogical strategies needed to teach and modify Italian consonants effectively.
This two-phase exploratory sequential mixed methods study identifies the features of Italian consonants that differentiate the lyric diction of novice singers from that of native speakers. It also proposes guidelines and exercises to improve the pronunciation of Italian consonants. The first qualitative phase examines the practices of Italian diction coaches based in the United States and Italy, all with experiences teaching college-level students and coaching professional opera companies. Their insights informed the creation of a set of targeted exercises for the quantitative phase.
Nine voice majors, seven who self-identified as women and two as men, aged nineteen to twenty-two, participated in the study. Each attended a lecture on Italian consonants and completed four testing sessions: a baseline, two coaching sessions targeting specific consonantal features, and a post-coaching recording. Acoustic data from pre- and post-coaching recordings were collected using the Kay-Pentax Computerized Speech Lab (CSL 4500) and analyzed with PRAAT. The same recordings were rated by a panel of native Italian speakers for perceived accuracy.
Advisor: Kevin G. Hanraha