• Aspects of vocal behavior of the raven (Corvus corax) in interior Alaska

  Brown, Roderick Neil; MacLean, Stephen F. Jr.; Kessel, Brina; Lent, Peter C. (University of Alaska Fairbanks, 1974-08)

  The vocal behavior of the Common Raven (Corvus corax principalis) was studied near Fairbanks, Alaska. Observations were made throughout the year on aggregations at feeding sites, soaring groups, nesting birds and birds en route to communal roost. Over 30 distinct call categories are distinguished on the basis of audible and audiospectrographic characteristics. Visual components of display which accompany the vocalizations are described for over 20 of the call categories. Kaww and Koww calls were the most frequently given vocalizations and were extremely variable within the population. Disyllabic calls (Kukwik, Kikkoo, Kulkulk) and multisyllabic calls (Kowulkulkulk and Kukuk) were the most stereotyped calls within the population. Visual components of display for disyllabic and multisyllabic calls were more stereotyped than visual components of display associated with monosyllabic calls. The highly evolved social organization of ravens and the plasticity of instinctive behavior patterns may account for its large and varied repertoire of acoustic signals.
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  Data-driven simulation of sustainable residential HVAC systems in Fairbanks, AK

  Young, Joshua; Kim, Sunwoo; Huang, Daisy; Peterson, Rorik (2025-05)

  Residential heating comes at extremely high costs and with harmful air pollution in many Alaskan communities. In Fairbanks, the issue of air pollution has received special attention in recent years, specifically due to the high concentration of small particulate matter resulting from residential space heating. This thesis aims to address energy insecurity and air pollution in Fairbanks by proposing an improved residential HVAC system. A computer simulation was developed to model the operations of several different HVAC configurations for comparison with standard heating oil boiler and portable air conditioner systems. This Python model provided a means of simulating one year of heating and cooling using TMY3 weather data, performance data from commercially available HVAC equipment, and historic energy pricing. The proposed HVAC system integrated a hybrid source heat pump with thermal storage, radiative sky cooling, and solar evacuated tube heating technology. Other tested systems included single and dual air source heat pumps, and water source heat pumps integrated with thermal storage, radiative sky cooling, and solar evacuated tube heating technology. Each of the tested systems were fitted with a backup boiler to meet the heating requirement in Fairbanks at the ASHRAE design temperature. A boiler and portable AC unit were also simulated in operation as a baseline for comparison to the tested systems. Each tested system was found to greatly reduce the operational cost, heating oil consumption, and associated CO2 and PM2.5 emissions compared to the baseline system. The proposed hybrid source heat pump system saw the greatest of these operational benefits, demonstrating operational cost savings of 19.12% and heating oil consumption reduction of 43.1% as compared to the heating oil boiler and portable AC unit. A benefit-cost analysis revealed that while each tested system showed operational benefits from the baseline, the increased maintenance costs associated with these complex systems outweighed the operational benefits. Furthermore, the capital costs were found to increase substantially with system complexity, creating a barrier to entry for users. While each tested system was found to lower operational costs and increase social benefit by reducing CO2 and PM2.5 emissions, the disproportionate capital and maintenance costs of these systems resulted in economic nonviability. This research highlighted the need for sustainable HVAC solutions for residential homes in Fairbanks. While these results showcased a modern-day application of the developed model in Fairbanks, the key contribution of this thesis was the development of a powerful, adaptable model which can simulate the operation of a variety of HVAC systems in different locations. The structure of the model allows the user to simply upload new location specific data to perform a one-year HVAC simulation in any location where this data is available. While this thesis uses a sample Fairbanks home in simulation, the simulated building’s construction geometry and material properties are easily adaptable, allowing the user to fully specify the desired building for analysis. Similarly, the selected HVAC equipment is easily adaptable, allowing the user to specify performance data for commercially available equipment, or even test new technology in a variety of locations and building applications. This adaptability allows the model to be applied for both residential and commercial buildings and used to simulate HVAC operations across a variety of locations for cost analysis, research and development.
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  Effects of iron nutrients in sub-arctic horticulture

  Woods, Susan A.; Duffy, Lawrence; Rasley, Brian; Barry, Ronald; Koskey, Michael (2025-05)

  When managing iron (Fe) nutrients in controlled environment agriculture (CEA) hydroponic systems at sub-arctic regions between latitudes 50 to 70 degrees north, it is important to understand how plants regulate Fe to maintain Fe homeostasis, which is important for the production of Fe proteins and photosynthesis processes. The research objectives of this study are as follows: 1) determine Fe nutrients that promote yearly cycles of high-quality crops, 2) examine the regulation of Fe between plant roots and vegetation, and 3) explore whether seasonal adjustments in Fe nutrients can promote Fe homeostasis and the production of high-quality crops. This study considers the use of ferrous sulfate-heptahydrate (FeSO4·7H2O), ferric citrate (Fe-Cit) and sodium hydrogen ferric diethylenetriamine pentaacetate (Fe-DTPA) in Rosie romaine lettuce. Results demonstrated how Fe-DTPA produced high-quality crops every season compared to FeSO4·7H2O and Fe-Cit. The Fe nutrients had different influences on Fe concentrations in lettuce roots and vegetation. From April to May 2019, high pH and light levels impacted lettuce production. Under Fe-deficient conditions, plants exhibited more Fe in vegetative portions than roots. From December 2020 to January 2021, low pH and the need for supplementary lighting slowed germination and growth. Plant weight decreased and plants exhibited more Fe in roots than vegetative portions. From July to September 2020, low pH and optimal sunlight produced high-quality lettuce and adequate Fe concentrations. Research demonstrated that seasonal adjustments in Fe nutrient management can promote high-quality crops and Fe homeostasis.
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  Developing a proof-of-concept non-scalable active vacuum insulated building envelope prototype

  Strailey, Kaarle P.; Marsik, Tom; Huang, Daisy; Bray, Matthew (2025-05)

  Heating and cooling buildings consumes around 17% of global energy demand. Improved thermal insulation can reduce much of this consumption with positive implications for energy security and economic opportunity. For over 25 years vacuum insulation panels (VIPs) have been considered a highly promising thermal insulation solution for building envelopes. VIPs can potentially provide an order of magnitude greater insulative performance than common insulation materials with the same thickness. However, the adoption of VIPs in buildings is hindered by many factors: their relatively high costs, installation challenges due to fragility, inalterability, and limited dimensions; limited service life in comparison to buildings due to loss of vacuum over time; susceptibility to thermal bridging along their edges; and other issues. An innovative concept in vacuum insulation technology, active vacuum insulation, is being developed to address many of these challenges. Incorporating a connection to a vacuum pump enables use of cheaper materials and equipment for on-site assembly and evacuation of customizable, large (for example, a whole wall) active vacuum insulation panels (active-VIPs). Vacuum can be extended indefinitely through occasional reactivation of the vacuum pump. For the project described in this thesis, a proof-of-concept active vacuum insulated building envelope prototype was developed. Large active-VIPs were produced and integrated with a vacuum assembly that created, monitored, and maintained internal vacuum. Over a one month trial period an average pressure of about 68 mTorr was maintained and the average R-value per inch of the active-VIPs was around 50 hr∙ft2∙°F∕Btu∕in. This was achieved using a minimal amount of electrical energy for the vacuum pump, representing less than 5% of the thermal energy saved thanks to the vacuum pump. These results indicate that active vacuum insulation is a worthwhile innovation for continued investment in research and development.
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  Post-typhoon Merbok impact on geographically isolated western Alaska communities and sustainable recovery process for vulnerable populations

  Schaffer, Daryl; Pennington, John; Carlson, Cameron; Fix, Peter; Valentine, David; Ainspan, Nathan (2025-05)

  A sustainable climate-resilient community depends on their location and what is considered to be resilient. In western Alaska, primarily sustainable Indigenous subsistence lifestyle communities have proven quite resilient to climate for over 5000 years. Indigenous communities have been experiencing exponentially greater challenges from changes of climate in recent years. One storm, which traversed the entire 1300-mile geographically isolated Alaska west coast in September 2022, was more significant than previous generations. Extratropical post-typhoon Merbok became part of a disaster cascade as many communities had already endured various disasters to their locations and livelihoods which made them more vulnerable to include prior climate-related land erosion, damage to infrastructure, food insecurity, and sustainable livelihood. Mitigation, response, and recovery planning policies are typically addressed from an urban and rural perspective but changes are needed to address the challenges found in remote and geographically isolated locations, which include the vulnerable populations. Federal, state, and local planning has not understood, nor taken into consideration, historical Indigenous knowledge of continual adaptation to climate. This dissertation will look at Merbok as a single storm, how Merbok cascaded and exacerbated existing problems of housing, food, geography, and infrastructure insecurity, and compare Merbok to similar storms impacting geographically isolated locations with similar underserved vulnerable populations. The findings and conclusions from this research will benefit local to federal emergency management professionals in addressing and adapting plans for communities in geographically isolated locations.
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  Performance and viability of air source heat pumps for residential heating in cold climates

  Samuel, Nick; Kim, Sunwoo; Peterson, Rorik; Huang, Daisy (2025-05)

  With an ever-increasing concern for Earth’s climate, solutions to mitigate further climate change caused by greenhouse gas emissions are continuously being investigated, one of which is heating buildings using air source heat pumps (ASHP) rather than traditional fossil fuel systems such as a furnace. The benefits of heat pumps over other heating methods such as resistive heating is their ability to transfer multiple times greater heat using the same amount of electricity by utilizing the phase change of a refrigerant and different inside and outside temperatures through use of the vapor-compression cycle. This also provides an advantage over fossil fuel-based systems by operating on electric power rather than burning fuel, greatly reducing greenhouse gas emissions. While heat pumps are a superior choice for many heating needs, heat pumps suffer performance issues when outside temperatures are low. This low coefficient of performance (COP) in cold climates has limited the widespread use of heat pumps to provide heat in the winter. The first section of this thesis will review heat pump technology and research on cold climate performance, including discussions on refrigerants, environmental impacts, and the economic cost of using a heat pump. A field test in Fairbanks, Alaska was performed and collected data on heat pump performance of a commercially available (CA) R410A-based ASHP and a prototype ASHP with new technologies and R32 refrigerant. Results of these tests revealed a 53.8% increase in COP of the prototype heat pump from -30°C to -35°C compared to the CA unit with a 26.7% average increase in COP over the 0°C to -35°C range, with increases to heating output seen as well. An economic comparison of a furnace heating system compared to both heat pumps also revealed generally lower operating costs for the heat pumps, with a potential hybrid heating system resulting in cost savings of 33% to 57% for the prototype unit and 17% to 45% for the CA unit. Year-long projections were performed for Fairbanks, AK as well as Boston, MA and Fargo, ND to evaluate performance, cost, and environmental impact in regions with different weather conditions and energy costs. Across all three locations, cost savings were seen from utilizing heat pumps over a furnace, with the Fargo location being more cost effective to use a heat pump 100% of the time. An analysis on levelized cost of heating was calculated for each location to evaluate long-term costs, with a discussion at the end about possible errors in calculations and projections.
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  Collective action in marine mammal co-management: relationships as tools of cooperation

  Ransdell-Green, Joseph E.; Wight, Philip; Meek, Chanda; Ehrlander, Mary (2025-05)

  Collective action has great importance in solving many socio-ecological issues because the sustainable management of natural resources requires that different people and institutions cooperate with one another to contribute to a collective good. Over the past sixty years, two general theories of collective action have formed. These theories continue to influence debates about what factors drive collective action. In the 1960s, first-generation collective action scholars proposed that laws from centralized governments or privatization were needed to combat collective action problems such as overpopulation and overexploitation of resources. Second- generation scholars argue that groups can self-organize to solve collective action problems. Elinor Ostrom and other scholars have used empirical evidence to show that groups are able to effect collective action independently of external factors. These researchers argue that social norms and values supporting reciprocity, fairness, and trustworthiness play an important role in successful collective action. These various forms of social phenomena, such as relationships and trust, are known as social capital. To investigate the factors of collective action, I partnered with the Indigenous Peoples Council for Marine Mammals (IPCoMM), an umbrella organization of marine mammal co-management Alaska Native Organizations. IPCoMM member organizations work with Alaska Native communities and U.S. federal agencies to jointly manage marine mammal species under the Marine Mammal Protection Act of 1972. This project is the first collective action research to be conducted in partnership with IPCoMM. The research reveals that the organizations are supporting their collective action efforts by strong relationships with one another and with federal agencies. Trust is one of the most important aspects of these relationships. The relationship-building and trust-building factors that foster collective action for IPCoMM include long-term relationships, frequent communication, face-to-face communication, respect for other viewpoints, inclusion within organizations, humility, personal bonds, and promise keeping. This research demonstrates that trustful relationships (or social capital) are integral to bringing diverse partners together for innovation and collaboration, and promoting collective action in marine mammal co-management in Alaska.
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  Places of life, places of death: caves in pre-Hispanic Huachichil conscience in northern Mexico

  Prashby, Kate; Cannon, Chris; Koskey, Mike; John, Theresa; Kuho, Yoko (2025-05)

  In 1931, a US geologist took ten skulls from a pre-Hispanic burial cave in historic Huachichil territory in northeastern Mexico and brought them to a US museum. To assist in repatriation efforts, this thesis uses ethnoarchaeology to suggest how ancient Huachichiles may have used caves and what they may have believed about those caves. Drawing from ethnographic accounts from the US Southwest, Aridoamerica, and Mesoamerica, this thesis establishes two possible models of belief that Huachichil cosmology may have followed regarding caves. A second pre­ Hispanic Huachichil burial cave and its surrounding caves are also examined using participant observation and interviews with a local Elder to determine any traditional knowledge related to ancient Huachichil cave use. The bioarchaeological analysis of the ten skulls from the first burial cave sheds some light on ancient Huachichil lifestyles. While there is little remaining traditional knowledge that would indicate ancient Huachichil cave beliefs, experiences with the ten skulls and the second burial cave affirm the Indigenous understanding that human remains are powerful and retain some essence of the person they belonged to. Repatriation is vital because human remains have consciousness and agency and are worthy of respect.
• Evaluation of hybrid enhanced oil recovery strategies for Ugnu heavy oil reservoirs in the Alaska North Slope

  Ogunkunle, Temitope Fred; Zhang, Yin; Dandekar, Abhijit; Ning, Samson; Nguele, Ronald (2025-05)

  The Alaska North Slope (ANS) holds a vast reserve of heavy oil, primarily in the Ugnu formation, estimated at 12-18 billion barrels. However, the recovery of these resources presents challenges due to high oil viscosity and proximity to continuous permafrost, which precludes thermal recovery methods that could cause disastrous environmental damage. Recently, low-salinity water flooding (LSWF) and low-salinity water with polymer (LSP) have been considered for enhancing oil recovery from moderately viscous oil reservoirs on the slope. This study explores non-thermal hybrid enhanced oil recovery (cEOR) techniques, focusing on solvent pre-treatment (e.g., CO2) and low-salinity water (LSW) within a Water Alternating Gas (WAG) injection method. Commercial silica sand packed in cylindrical sandpacks was used throughout the study to evaluate the recovery performance of the proposed methods on both dead and live Ugnu heavy oil. Various injection modes were also examined to optimize recovery performance. Cumulative oil production and pressure drops were measured and recorded, while oil recovery factors and residual oil saturation after each flooding were determined based on material balance. The displacement test results reveal that combining liquid CO2 with LSW in a WAG process significantly enhances recovery, achieving up to 83.5% of original oil in place (OOIP), more than double that of continuous LSW flooding. This improvement is attributed to CO2-induced viscosity reduction and swelling, with additional benefits of CO2 storage in the reservoir. Hydrocarbon lean gas (HLG) was also evaluated as an alternative solvent, but the performance was lower (68.4% of OOIP) compared to liquid CO2 due to differences in mass transfer and live oil interactions. Simulation studies optimized key parameters for the CO2-WAG process, such as soaking time and CO2 slug volume, highlighting the potential for maximizing recovery while sequestering greenhouse gases. Another promising approach, CO2-saturated low-salinity water (CWI), demonstrated substantial recovery benefits, achieving an additional 36% OOIP beyond secondary LSW injection and 40% in tertiary stages. The effectiveness of CWI lies in viscosity reduction and solubility trapping of CO2 in residual oil, with 28-41% of injected CO2 stored during the process. However, integrating low-salinity water polymer (LSWP) in tertiary recovery was less effective due to polymer degradation. Overall, these studies underscore the significant potential of CO2-based cEOR methods, particularly liquid CO2-WAG and CWI, for Ugnu heavy oil recovery. These techniques not only improve oil recovery but also contribute to greenhouse gas mitigation through efficient CO2 utilization and storage.
• Universe, baby and other weirdness

  McIntyre, Nóra; Holt, Joseph; Torres, Kavelina; Reilly, Terry (2025-05)

  Universe, baby and other Weirdness is a collection of short and flash fiction, poetry, and a hybrid novella. The pieces in this work employ supernatural, surreal, or otherwise strange elements in order to explore themes of love, monstrosity, loneliness, and loss. Many of the pieces in the collection also grapple with questions of selfhood, sexuality, and the connection between the individual and their community. The collection experiments with hybrid form, most notably in the titular novella, Universe, baby, which takes stylistic inspiration from classic Greek tragedies, as well as epistolary literature and “found footage” horror films. While the author is heavily influenced by their study of the horror genre and the tragic form, this collection rejects the constraints of any one particular genre.
• From the sea to the classroom: harmful algal blooms, northern sea otters, and engaging curriculum

  Mailman, Emily; Atkinson, Shannon; Branson, Maile; Causey, Douglas (2025-05)

  Harmful Algal Blooms (HAB) consist of a myriad of phytoplankton that can produce multiple potentially lethal biotoxins, which are ingested by shellfish as they consume algae in their diet. HAB events can occur when sunlight, nutrients, temperature, and turbidity conditions combine optimally. These bloom events are expected to increase as ocean temperatures continue to rise. The present study takes a multifaceted approach to evaluate the concentrations of paralytic shellfish toxins (PST), in northern sea otters (Enhydra lutris kenyoni), and provides a curriculum for students in grades 9-12 to support student’s conceptualization of microscopic phytoplankton and their roles in coastal ecosystems. The first aspect of the project evaluates PST congeners in northern sea otter stomach contents and body fluids using high-performance liquid chromatography post column oxidation from samples that were collected in Icy Strait from subsistence hunters near Gustavus, Alaska. The predominant stomach content species identified include butter clams (Saxidomous gigantea; n=7), horse clams (Tresus capax; n=16), horse mussels (Modiolus modiolus; n=14), pink neck clams (Leukoma staminea; n=2), and softshell clams (Mya arenaria; n=3). Body fluids analyzed were from 2015 samples, and included serum (n=5), whole blood (n=3), stomach fluid (n=5), and urine (n=5). The second aspect of the project includes the creation of a curriculum that consists of ecosystem-based discussions, field collection, laboratory safety, microscopy, and concludes with a creative evaluation. Students are evaluated using a creative media/method to explain how phytoplankton have the potential to negatively impact ecosystems and how such impacts may evolve in coming years, decades, or generations. This curriculum is geared towards non-traditional classrooms, Tribal or coastal communities, field courses, and multi-generational gatherings. Developing climate-focused curricula alongside traditional academic laboratory techniques increases accessibility to various user groups and supports fostering students who will go on to make climate-focused decisions in their daily lives, communities, and future careers.
• Culturally responsive teaching practices at West Valley High School, Fairbanks North Star Borough School District

  Lehmkuhl, Connor; Plattet, Patrick; Drew, Elaine; Skinner, Olga (2025-05)

  This research examines the pedagogical model of Culturally Responsive Education and how it is implemented in urban Alaska (Fairbanks). The main objective is to document the voices, perspectives, and opinions of individuals and schools who are engaged and/or interested in Culturally Responsive Teaching Practices at a time when the interest in this topic is growing. As a result, this thesis allows for a better understanding of these practices, as well as of their applicability to existing curricula. The main research questions are (1) What is the current understanding of Culturally Responsive Education among global studies teachers at West Valley High School in the Fairbanks North Star Borough School District? And (2) What are the specific teaching practices that are being developed and implemented by teachers in the classroom in conjunction with this understanding of Culturally Responsive Education? The ethnographic data for this research was produced during two months of fieldwork at West Valley High School in Fairbanks through classroom observations and semi-structured interviews with global studies teachers and student teachers, as well as members of the administrative personnel (principal and assistant principal). The themes that emerged through data analysis include: the value of “positive relationship building,” “community,” application-based learning, and the need to allocate more resources to address challenges faced by teachers impacting their ability to effectively implement Culturally Responsive Education in the classroom. From an anthropological standpoint, it becomes apparent that Culturally Responsive Education is a culturally grounded and therefore powerful set of tools that has the potential to simultaneously increase student engagement and decrease the systemic impact of stereotyped views of “student behaviors”.
• Hyperspectral remote sensing of potential mineral resources at Elephant Mountain, Interior Alaska

  Javed, Khawaja Ahad; Nadin, Elisabeth; Stuefer, Martin; Schmitt, Carl (2025-05)

  This study explores the application of hyperspectral remote sensing for mineral mapping purposes at Elephant Mountain, Interior Alaska, focusing on airborne and laboratory-based spectroscopic techniques. Hyperspectral imaging (HSI) was conducted using the HySpex imaging system, acquiring airborne hyperspectral imagery over an area of proven mineral resources. The research aimed to evaluate the effectiveness of HSI in identifying alteration minerals, considering the impact of spatial resolution, sensor altitude, and spatial resampling on mineral detection accuracy. A spectral feature-fitting algorithm within the USGS-developed PRISM software was employed to compare airborne-derived spectra with USGS spectral library standards. Laboratorybased spectrometric analyses of rock samples collected from the field area were conducted to validate airborne results. Detailed maps of iron-bearing minerals were made from the visible-near infrared (VNIR) part of the spectrum. Preliminary data analysis indicated widespread lichen coverage in the study area, leading to a detailed analysis of how lichen spectral features overlap and interfere with the spectral features of key alteration minerals in the shortwave infrared (SWIR) part of the spectrum. Synthetic spectral mixtures of lichen and minerals were generated to quantify these effects, demonstrating how lichen presence alters the position of absorption feature of SWIR minerals, leading to misclassification of minerals as lichens. The results emphasize the need to correct lichen interference in hyperspectral mineral exploration, particularly in high-latitude terrains where biological cover is prevalent. This study also presents an analysis of choices leading to optimal spatial resolution in hyperspectral mineral mapping, by analyzing HSI at varying resolutions and sensor altitudes. Findings indicate that while finer spatial resolutions improve mineral classification accuracy, increased sensor altitude and resampling can degrade mapping results. Mineral exploration in remote regions of Alaska will benefit from understanding how lichen can interfere with mapping key alteration minerals, what information can be derived in such a circumstance, and what options to choose when deciding on flight altitudes and processing steps.
• A zooarchaeological analysis of far-north Goldrush-era sites

  Jansen, Amelia M.; Cramb, Justin E.; Reuther, Joshua; Shirar, Scott (2025-05)

  The current accumulation of archaeological investigations at far-north Alaskan Goldrush sites either completely lack or severely underrepresent the faunal components. These data are vital and add context to past and future archaeological investigations by enabling more accurate and inclusive interpretations of life in the mining-related settlements of the far north. This research is an analysis of previously unidentified and partially identified faunal assemblages from Goldrush- era archaeological sites in Interior Alaska including Coldfoot, Fairbanks, Tofty, Wiseman, Eagle, Uhler Creek, and Marion Creek. The data generated from the analysis of these diverse sites and site types helps determine how animals were being utilized by the residents of differing mining- related settlements and complements previous research completed on trade goods while informing upon imported (domestic) and localized (wild) resource use.
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  At the crossroads of technology, policy, and society: energy transitions in rural Alaska

  Holdmann, Gwen; Wies, Richard; Poelzer, Greg; Hirshberg, Diane; Huang, Daisy (2025-05)

  The future of energy in remote and rural communities is shaped by a complex interplay of technology, policy, and social structures. This dissertation explores why some regions--despite facing similar economic, geographic, and environmental constraints--have successfully developed renewable energy systems while others have struggled. Focusing on rural Alaska, this research examines the factors that drive or inhibit local energy transitions, considering historical institutionalism, governance structures, policy interventions, and economic incentives. Through a mixed-methods approach including case studies, qualitative comparative analysis, and statistical methods, this dissertation examines how energy subsidies and the pooling of resources--whether through shared infrastructure, cooperative utilities, or other forms of regional collaboration-- shape energy costs, innovation, and renewable energy adoption in isolated communities. The findings highlight the pooling of resources as a key driver of successful energy transitions and offer insights applicable to other Arctic and remote regions. By bridging engineering, policy, and social science, this work challenges dominant narratives that view energy transitions as purely technological or economic shifts and argues that sustainable energy futures emerge from balancing past wisdom and innovation. Informed by diverse perspectives including those of communities, utilities, and Alaska's Indigenous knowledge systems, this dissertation reframes the approach to energy transitions, emphasizing the integration of historical wisdom, policy adaptation, and local agency. Rather than discarding old systems for new ones, integrating historical knowledge with modern solutions is key to building resilient, affordable, and community-driven energy systems. The findings contribute to ongoing discussions in academia, policymaking, and practical decision­ making, offering insights relevant to scholars, practitioners, and leaders working on rural and Arctic energy transitions.
• Vegetation analysis and mapping in evolving ice-wedge-polygon terrain Prudhoe Bay Region, Alaska

  Hobgood, Olivia; Walker, Donald A.; Breen, Amy L.; Raynolds, Martha K.; Kanevskiy, Mikhail; Frost, Gerald V. (2025-05)

  The Arctic is warming at an accelerating pace, and within the past few decades, ice-rich regions of the Arctic have undergone systemic changes. The subsidence of ground over degraded ice wedges has created new drainage networks and ponds within previously perpetually inundated areas, fundamentally altering ice-wedge-polygon landscape dynamics. Understanding the nature and distribution of these changes is crucial to determining potential impacts on climate, wildlife, and human society. We focus on an accessible and data-rich region within Prudhoe Bay. Although the changes caused by this shift in moisture regime are multi-faceted, we use vegetation as an easily measured proxy for multiple factors. Within this thesis, we delineate and describe the post-regime-shift vegetation at the study site along with corresponding environmental data. Following vegetation description, we map this vegetation at a very fine spatial scale (<1-m) using an automated approach suitable for efficient spatial and temporal repetition. Our results show that vegetation is strongly influenced by soil moisture, and consequently microrelief, making it a suitable indicator of inundation or drainage following permafrost subsidence. Moreover, novel vegetation types have been identified in both newly inundated and newly drained areas. Mapping results show that distribution of vegetation types is strongly influenced by surficial geology, and consequently ice richness. Older surfaces with thicker ice wedges have a higher cover of dry and moist vegetation types on drained polygon centers in addition to transitional aquatic vegetation within thermokarst ponds. Younger surfaces with thinner or absent ice wedges remain inundated, and have a higher cover of wet vegetation in addition to shallow, sparsely-vegetated lakes and ponds. We recommend further vegetation sampling at the study site to support development of a pan-Arctic vegetation classification, and additionally to better understand vegetation dynamics in enriched areas within close proximity to oil field infrastructure. We also recommend temporal repetition of the mapping approach in order to identify continued landscape changes over time.
• Mechanical properties of biofilms in water distribution and bioremediation systems

  Hasan, Md Ibnul; Aggarwal, Srijan; Dev, Subhabrata; Schiewer, Silke; Schuette, Ursel (2025-05)

  This dissertation explores biofilm dynamics in water distribution and acid mine drainage (AMD) treatment, focusing on their roles in resource recovery and public health. Biofilms consist of microbial communities in a self-produced extracellular polymeric substance (EPS) matrix, which influences their mechanical and structural properties based on EPS composition, environmental conditions, and biofilm age. In drinking water distribution systems (DWDS), biofilms pose health hazards as they harbor pathogens and encourage metal corrosion. The composition of extracellular polymeric substances (EPS), particularly its high protein content, is noted in downstream areas, facilitating biofilm development in conditions of reduced chlorine and higher temperature turbidity. Traditional antimicrobial strategies often fail due to the protective EPS matrix, highlighting the need for targeted biofilm control strategies. On the other hand, biofilms show promise in AMD treatment, where biofilm-based bioreactors utilizing sulfate-reducing bacteria (SRB) effectively neutralize acidity and recover valuable metals, including rare earth elements. SRB bioreactors demonstrated sulfate reduction rates of up to 92.8% and near-complete removal of essential metals, showcasing the ability of biofilms to facilitate precipitation and biosorption under extreme conditions. The mechanical properties (as Young’s modulus) of biofilms were observed to vary with environmental conditions and biofilm age, influencing their resilience to mechanical stress. In DWDS, these properties impact biofilm control and removal efforts, while in AMD treatment, increased biofilm stiffness supports structural stability for effective metal removal. Advanced techniques like confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) assessed biofilm characteristics, emphasizing the need for site-specific management strategies. Findings indicate that successful biofilm management necessitates an understanding of mechanics, EPS composition, and environmental factors. Future research should enhance biofilm control technologies and explore enzyme-based disruptors, balancing sustainability and public health concerns while optimizing resource recovery.
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  Control of invasive plants at high latitudes with persistent herbicides: understanding persistence, to manage pesticide residues and achieve effective control

  Graziano, Gino; Zhang, Mingchu; Mulder, Christa P. H.; Seefeldt, Steven; Tomco, Patrick (2025-05)

  Invasive plants are considered a problem in management of natural resources and maintenance of ecosystem services in Alaska. Persistent herbicides are often used to control invasive plants because of increased duration and efficacy of control; however, applicators must understand that persistence impacts rotations to sensitive crops or restoration to sensitive desirable species. The purpose of this study was to define and document the impacts of aminopyralid and clopyralid degradation and movement in boreal ecosystems when used in agricultural settings or applied to Prunus padus, a problematic invasive tree in the boreal ecosystem. In laboratory microcosms clopyralid did not adsorb to soil particles under any conditions. Aminopyralid adsorbed to soil particles with increased adsorption at lower pH due to protonation of the amine group. Amnopyralid and clopyralid were compared in agricultural field treatments of fallow ground, followed by two years of small grain production before rotation to field peas, a sensitive species in the third year. Herbicide was detected one year after treatment with both herbicides, but by two years after treatment only aminopyralid was detectable in soil. Bioassays performed with these same soils had a similar pattern with smaller plants 1 and 2 years after treatment, but no indication of herbicide 3 years after treatment. Despite the lack of detection in soils, herbicide sensitive field peas were unable to grow in aminopyralid treated plots 3 years after treatment, indicating the presence of biologically significant concentrations of herbicide. Aminopyralid applied to stems of invasive Prunus padus saplings was exuded from the roots of treated trees, with herbicide detected in soils and resulting in damage to some susceptible species. Applications of triclopyr resulted in the detections of herbicide and observations of non-target damage without significant change in defoliation of the target trees. Reduced rates were equally effective for aminopyralid.
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  Wave driven diffuse aurora and ionospheric conductance global patterns

  Gillespie, Dillon M.; Öztürk, Doğacan Su; Connor, Hyunju; Hampton, Don; Newman, David; Zhang, Xiao-Jia (2025-05)

  Auroral precipitation is the second major energy source after solar irradiation that ionizes the Earth’s upper atmosphere. In this study we define 3 types of auroral activity as broadband, monoenergetic, and diffuse aurora. Diffuse aurora from electron precipitation, or diffuse electron aurora, contributes over 60% of the total auroral energy flux. Through constant collisions between the electrons and neutral particles in the atmosphere the electron flux ionizes the atmosphere and strongly contributes to the ionospheric conductance. The ionization, electron energy flux, and conductance play a significant role in defining the ionosphere-thermosphere dynamics. One major contributor to the precipitation of these electrons in the inner- magnetosphere is wave-particle interactions. By resonating with the electron gyrofrequency of electrons in space, specific plasma waves can change the particle energy and cause precipitation into the Earth’s atmosphere. Chorus banded waves and Electron Cyclotron Harmonic waves (ECH) are major contributors to electron precipitation because of their occurrence and wave frequency. The propagation of these waves and the influx of electron population in the inner magnetosphere has a strong dependency on geomagnetic activity. This dissertation quantifies the impact of Chorus and ECH waves on diffuse electron aurora and ionospheric conductance during quiet, medium, and strong geomagnetic activities. Using observations from the Timed History Events and Macroscale Interactions during Substorms (THEMIS) satellite probes we produce a statistical baseline for the electron flux rates, wave amplitude and observation statistics, and inner-magnetosphere conditions such as electron temperatures and densities. We directly derive the energy flux spectrum of diffuse electron precipitation using quasi-linear theory with these observations as initial conditions. We then calculate the height-integrated conductance from the wave-driven aurora spectrum using an electron impact ionization model to determine the rate of ionization and the US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar (NRLMSISE-00) model from the 2000s for neutral atmosphere components. By utilizing Fang’s (2010) ionization model, NRLMSISE-00 for the neutral atmosphere components, and the University of California, Los Angeles (UCLA) Full Diffusion Code, we improve upon the standard generalization of Maxwellian diffuse electron precipitation patterns and ionosphere conductance statistics. Our study of global auroral precipitation and ionospheric conductance from both Chorus and ECH wave statistics allows us to quantify, for the first time, the relative contributions of these two waves. We show that the total electron flux and conductance pattern from our results agree with those of the Ovation Prime model over the pre-midnight to post­ dawn sector as geomagnetic activity increases. Our study examines the relative contributions of Upper Band Chorus (UBC) and Lower Band Chorus wave (LBC) driven conductance in the ionosphere. We found LBC waves drove diffuse electron precipitation significantly more than UBC waves, and that their combined precipitation and conductance was greater than the impact of ECH waves by 30% for high activity and upwards of 70% more for low geomagnetic activity.
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  Sea ice strain, stress, and fracture activity at kilometer scales

  Fedders, Emily R.; Mahoney, Andrew R.; Hutchings, Jennifer K.; Meyer, Franz; Polashenski, Chris; Richter-Menge, Jacqueline (2025-05)

  Through-thickness fractures including cracks, leads, and pressure ridges divide sea ice into individual plates and plate assemblies. While they remain intact, plates deform via continuous strain as they interact. Radar interferometry can identify active fractures at plate assembly boundaries and measure the continuous strains between them at high spatial resolution and spatial scales from meters to kilometers. However, interferograms are only sensitive to the one­ dimensional component of surface strain parallel to a radar’s lines of sight. Working with coauthors, I develop a novel analytical inverse model to estimate two-dimensional, horizontal surface motion from the one-dimensional information provided by interferograms over areas of ice experiencing spatially uniform strain. Model results accurately capture thermal strain in sheltered landfast ice and realistically estimate rigid displacements in drifting ice. In areas of non-uniform strain, we combine one-dimensional interferometric strain measurements with field observations from a sea ice camp in the Beaufort Sea to investigate relationships between strain, stress, and fracture activity. We calculate the first published estimates of the effective elastic modulus, E*, and effective Poisson’s ratio, v*, of in situ drifting sea ice under natural loading rates. We estimate E* within the range typically used in sea ice models but estimate v> > 0.5, larger than typically assumed and indicative of anisotropy in sea ice Poisson response at low strain rates. Finally, we synthesize interferometric records of strain and fracture to identify an approximately 1 km radius of influence of impact forces resulting from contact across active fractures. We also identify apparent fracture reactivation after multi-day quiescent periods, indicating prior fractures may remain weaker than surrounding ice for such periods. Together, this work outlines both new observations and new tools for future researchers to utilize in studies of sea ice mechanics and dynamics at intermediate scales in areas of high-concentration winter pack ice.

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