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<p>Bacterial biofilms are problematic in a variety of industries hence strategies for their mitigation have received significant attention. The approach described herein attempts to control bacterial adhesion using silicone-based polymers- (widely used due to their interesting properties)- via manipulation of their surface chemistry to eventually create anti-fouling surfaces. This involved study of the systematic variation of surface wettability and its effect on <em>Escherichia coli</em> (<em>E. coli</em>) adhesion to novel polymers of acrylate-modified silicone surfactant (ACR) with either hydroxyethyl methacrylate (a hydrophilic monomer), or methyl and butyl methacrylate (hydrophobic monomers). It was hypothesized that the systematic variation of ACR would produce surfaces with differing wettability, without changing other surface properties that influence cellular adhesion. Average light transmittance across the range of visible light wavelengths (400-740nm), surface roughness and Shore 00 hardness data were consistent across the ACR-HEMA copolymer series (80-90%, ~2.5 – 5 nm, and 75-95 Shore durometer points, respectively). The same consistency was observed for surface wettability (contact angles = 78-92°) despite varying HEMA content and consequently <em>Escherichia coli</em> (<em>E.coli</em>) adhesion, likely due to system saturation with silicon (as confirmed by EDX). However, wettability of the ACR-MMA-BMA polymers did vary; ≤ 20 wt% and ≥ 80 wt% ACR polymers had contact angles between 67°- 77°, while 20 < x < 80 wt% ACR polymers had increased surface wettability (contact angles 27.6°- 42.9°). <em>E. coli </em>adhesion across the set increased with increasing ACR content, a trend mirrored by the water uptake of the materials but not the contact angle data. These results indicate that <em>E. coli </em>adhesion occurs independently of wettability for these materials and although the effect of the latter on adhesion cannot be deduced, the possible correlation between bacterial adhesion and water uptake suggests that the best antifouling surfaces should not be of materials capable of imbibing significant amounts of water.</p> / Master of Applied Science (MASc)

Recent research suggests that race and ethnicity influence post-buyout land management in Harris County, Texas, yet lacked systematic empirical evidence to fully understand the relationship between management and demographics. To address this gap, this study analyzes post-buyout land use management practices and compares them with the socio-economic characteristics of the adjacent neighborhood at the block level in Harris County, Texas, an area with a long buyout history. I first identified post-buyout land use management practices in Harris County through county records and photo documentation of approximately 2000 buyout sites through fieldwork from 2017-2022. Second, using Ode and colleagues' framework for identifying visual characteristics on the landscape, I developed an index and evaluated post-buyout land use management practices for aesthetics, utility, and function. Finally, I spatially analyzed the socio-demographic composition of buyout neighborhoods using U.S. Census American Community Survey 5-year data (2017-2021) and compared it with post-buyout land use management practices in ArcGIS. From this spatial analysis, I identified differences in post-buyout land management that homeownership status, race, and ethnicity affected post-buyout land management. Most buyout properties in Harris County are managed as mowed, vacant lots regardless of socio-demographics; however, litter and debris were more prominent in predominantly Black neighborhoods. Of note, higher utility land uses were more frequent in predominantly white neighborhoods, but buyout sites developed into parks were located in lower-income and predominantly Hispanic areas suggesting variance in land use by socio-demographics.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24887号 / 工博第5167号 / 新制||工||1987(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 教授 堀 智晴, 教授 山上 路生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Forests perform many important ecological functions and provide numerous environmental services to humanity. Currently forests are under ever increasing pressures from humans through deforestation, changes in land use, and anthropogenic climate change. Managed forests play an important role in supplying forest products to the global population, necessitating the need to predict how forests will respond to climate change and how this will influence future wood product supplies. In this dissertation I used loblolly pine (Pinus taeda), the most extensively cultivated tree species in the United States, as a study system to simulate how climate change and forest management could alter the dynamics of managed forests in the future. Using the land component (the Community Land Model) of the widely used Community Earth System Model (CESM), I developed and validated a set of tools necessary to simulate the loblolly pine plantation system using the vegetation demography model embedded in CESM (FATES). This included developing a representation of loblolly pine using data from the literature, which was better able to capture forest growth and development observed in field studies than FATES's existing conifer tree representation. I added the ability to simulate several aspects of forest management not previously supported in FATES by creating the Vegetation Management Module, which I showed was able to realistically reproduce the common management practice of stand thinning. I used these new tools to perform simulations of how loblolly pine will grow across the Southeastern United States until the end of the 21st century, under the high and low climate change scenarios developed by the scientific community in the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our experiments show that loblolly pine productivity may as much as double by the end of the century, with total wood harvest over that period increasing by almost half. I also showed that different management activities had significant effects on loblolly plantation yields, with mid-rotation stand thinning having an effect under both climate scenarios on par with increases due to the extreme climate change scenario SSP5 RCP8.5. I showed that these changes in wood yields could decrease the forest area in the Southeast required to meet the wood product demands over the rest of the century. These changes in plantation productivity could interact with socioeconomic factors to drive changes in land use and carbon storage in the Southeastern U.S. This work increases our understanding of how managed forests in the U.S.\ will be affected by climate change and how our management choices modulate that response. The techniques and tools developed here open up new areas of research into the role of forest management in the climate system. / Doctor of Philosophy / Forests benefit humans by regulating Earth's climate and by providing natural resources such as wood. In the Southeastern United States forestry is an important industry. Tree farms of southern pine trees produce a large percentage of the region's wood. Predicting how forests will grow in the future is important for planning and making investments. However, the burning of fossil fuels has increased carbon dioxide in the atmosphere and is changing Earth's climate. This is affecting how fast trees grow and how much wood can be harvested from forests. The methods that foresters have traditionally used to predict how trees will grow in the future do not account for climate change, and thus may not be as accurate in the future. An alternative is to use the computer models that scientists have developed to predict both how global climate will change in the future and how forests are influenced by climate. These computer programs can be used to predict how natural forests will grow in the future, but aren't set up to predict managed forests well. I made changes to one of these programs to make it possible to simulate the managed loblolly pine forests of the Southeastern United States. First, I tested these changes to make sure that simulated forests grew like real forests do today. Then I simulated how pine forests in Southeastern United States could grow over the next century with climate change. I found that pine forests will grow faster and allow more wood to be harvested as carbon dioxide in the atmosphere increases. If climate changes are extreme, loblolly forests could produce 70\% more wood than today by the end of the 21st century. I also showed that the manner in which forests were managed in simulations changes the amount of wood they produced, with some management practices increasing wood harvested by 50\% over the rest of the century. Because climate change could increase the amount of wood that can be produced from a fixed area of forest, I investigated how this might change the area of forest plantation in the Southeastern United States. Based on projections of demand for wood for the rest of the century I calculated how much loblolly pine forest would be needed to produce this wood over the next century. I found that increases in forest productivity due to climate change and forest management could decrease the forest area required to grow the wood we need. This could change how we use forests in the Southeastern United States, which in turn could have impacts on the climate.

This dissertation is composed of three essays; the first two examine the decisionmaking of potato producing households in Bolivia and the third examines well-being changes among Zimbabwe households. The first essay entitled “The role of risk mitigation in production efficiency: A case study of potato cultivation in the Bolivian Andes” estimates the costs of self-managing environmental risk through activity and environmental diversification. Risk management has the potential to reduce income variability but at the cost of increasing production inefficiency, which we measure employing a stochastic production frontier. Among variables capturing environmental diversification, discontinuity between fields has the most detrimental effect on production efficiency. Activity diversification, measured by the ratio of potato to total crop revenue, has a stronger impact on inefficiency and yield losses than any of the environmental diversification variables. The second essay entitled “Determinants of market participation decisions and marketing choices in Bolivia” examines three decisions related to potato market participation: market entry, volume sold, and market choice. The first two are analyzed using a Heckman selection model. Results indicate that isolation, measured by population density and distance to markets, negatively impacts market entry. The most important determinant of quantity sold is land holding. Market choices are judged according to second-order stochastic dominance (SOSD). Market choices meeting the SOSD criterion are referred to as optimal marketing strategies as they have the higher expected payoff for a minimal income variance. Results suggest that the probability of selecting an optimal marketing strategy increases with quantity sold, access to market information, and access to liquidity while it decreases with distance to markets. The third essay entitled “A profile of changes in well-being in Zimbabwe, 2001- 2007/8, using an asset index methodology” shows that it is possible to examine intertemporal and spatial changes in well-being in the absence of consumption expenditures data by using an asset index. The asset index was constructed using Polychoric Principal Component Analysis. Results indicate that poverty and extremely poverty grew significantly in rural Zimbabwe while in urban areas, poverty diminished and extreme poverty grew. / Ph. D. / LTRA-7 (Pathways to CAPS in the Andes)