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Architectural solutions for hydraulically-coupled material transport in plants
No full textWhether for removal or retention, the movement of materials through a plant's body is a crucial aspect of its life. Much emphasis has been placed on the active biological processes involved in plant transport problems, but I argue that their physical and architectural solutions must also be considered. In this dissertation, I use mathematical modeling, complemented by imaging studies and physiological measurements, to explore the structural basis for the hydraulically-coupled transport of materials in plants.
In Chapter 1, I explore the structural properties required for safe and efficient desalination in secreting halophytes. Efforts to understand and manipulate gland-mediated secretion typically focus on the optimization and regulation of ion transporters but often neglect its biomechanical underpinnings. Using Nolana mollis as a model system, I integrate anatomy, physiology, and theory to show how the structural maintenance of a distinct subcuticular space is necessary to circumvent the energetic limitations of ion transport against steep concentration gradients across the cell membrane. I show that the integrity of this separate compartment determines the functional state of the salt gland and depends on the fracture mechanics of the gland’s cuticle. By exploring the biomechanical determinants of secretory salt tolerance, this work offers insights into alternative approaches for engineering salt-tolerant agriculture or biomimetic desalination devices.
In Chapter 2, I clarify the physiological function of the enigmatic transfusion tissue of conifer needles, which has remained unclear despite extensive anatomical characterization. Ubiquitous among conifer needles, the transfusion tissue mediates the radial transport of water and sugar between the endodermis and axial vasculature and faces potential bottlenecks at both of its boundaries, where the opposition of sugar and water flows may frustrate sugar export. Using anatomical data from imaging studies of Pinus pinea needles, I develop a network model of the transfusion tissue to explore how its structure and composition affect the delivery of sugars to the axial phloem. I show that bisection of the transfusion tissue into separate water- and sugar-conducting pathways, along with a branching structure between the vasculature and endodermis, mitigates interference between the inbound diffusive sugar flux and the outbound advective water flux. This work resolves the structure-based function of the transfusion tissue under conditions free of physiological stress and establishes the groundwork for further research of the transfusion tissue's physiology in other gymnosperms.
In Chapter 3, I model the coupled transport of methane and water through wetland trees to understand the structural and environmental determinants of arboreal methane emissions. Trees are important pathways for methane, which can be taken up by roots within the waterlogged, anoxic zone and released from the trunk directly into the atmosphere. I develop a model of a typical tree within a swamp to explore methane dynamics over a range of environmental and physiological conditions, in the context of measurements made in wetland Nyssa sylvatica. The model explores the parameter space of fundamental properties that affect patterns of arboreal methane emissions. Using insights from the model, I identify pertinent questions to advise the design of future empirical studies. By describing the relevant physiological and environmental parameters of this problem, the model provides a foundation for scaled-up predictions of tree-mediated methane emissions.
Given the near-infinite solution space for a plant's architecture that arises from its modularity, modeling offers a useful approach to organizing and distilling the physiologically relevant information. In this dissertation, I build models to explain these transport phenomena and further ground and contextualize those models in empirical observations.Biophysic
Soulful Wellness and the Black Paradox: Reorienting Mind, Spirit, and Culture A Theological-Psychological Inquiry into Healing, Identity and Sacred Survival
No full textThis paper addresses the importance of religion in the African American community's mental health and healing practices, drawing on both African-derived traditions and Christian faith practices. Historically, African Americans have faced institutional oppression, racial trauma, and socioeconomic marginalization, but their resilience has frequently been strengthened by the incorporation of religious traditions. This study demonstrates how African religion, and the Black Church anchor both psychological survival and communal resilience in the face of generational suffering. The research also scrutinizes how medical and psychiatric institutions have traditionally pathologized Black religious expression, using terms like drapetomania and the labeling of "religious excitement." These actions criminalized culturally meaningful worship and fueled long-standing distrust of mental health services in Black communities. Drawing on cultural anthropology, theology, and neuroscience, this study also identifies faith as a fundamental mechanism for trauma recovery and resilience development. Presenting a culturally sensitive intervention paradigm based on the Health Belief Model, this research is tailored to the needs of African American communities. This paradigm highlights the importance of religion leaders, churches, and community networks in increasing mental health literacy and eliminating stigma. It also emphasizes African American religious traditions as viable and effective instruments for healing trauma and promoting well-being. Ultimately, the article advocates for a collaborative, multidisciplinary approach to mental health care for African American communities' lived experiences, cultural traditions, and religious practices to achieve holistic healing.Author's Origina
Sanctuary: A Counter-Project for the Sacramento-San Joaquin Delta
No full textThe California Department of Water Resources has invested trillions of dollars in creating a centralized water supply system that has historically made the agricultural economy and Southern California’s urbanization possible. However, this system that exports and conveys waters, through the State Water Project and the Central Valley Project, is precarious and riddled with seismic risk, flooding, and subsidence problems. Moreover, it has largely viewed the Delta region as a sacrifice zone, ecologically and socioeconomically.
Using the lens of fish, this thesis proposes a public subsistence fishing destination and restorative fish habitat that creates opportunities for local water access and stewardship, while also addressing the precarity and exclusion of local communities that plagues the current system of water conveyance.Department of Landscape Architectur
A Proposed Framework for Optimally Managing Fisheries
No full textA fishery is an interconnected marine ecosystem where people fish for commercial and recreational purposes. As fishermen continue to fish, the total fish stock depletes, stressing marine ecosystems. Furthermore, climate change and other external environmental stressors continue to damage marine habitats, making fish more prone to dying or migrating to different areas in search of food. This alters the species composition within fisheries. The dynamic nature of these fisheries suggests that fishery managers must find ways to create models that account for increases or decreases in particular fish species and how these changes will affect the state of the current marine ecosystem. To preserve these natural ecosystems and ensure that people can continue to survive and thrive, institutional and governing bodies need to understand how to optimize the yield within these multispecies fisheries. One of the primary issues fishery managers are currently struggling with is the failure and resistance to modeling multispecies fisheries. This resistance stems from data gaps, resource limitations, management inertia, familiarity with single species models, and social constraints that inhibit institutional bodies from addressing the multispecies issue. This paper aims to create a multispecies theoretical model that encompasses interactions between species, which policymakers can rely on to build more precise and effective models. The theoretical framework proposed by this paper calls for the elimination of banking quotas. It also suggests that policymakers must more deeply consider harvest patterns and species interactions when thinking about distributing and allocating quotas to vessels.Applied Mathematic