Sub-communities within this community

Recent Submissions

  • Development of Landslide Warning System

    Riad, Beshoy; Zhang, Xiong (2019-11)
    Landslides cause approximately 25 to 50 deaths and US$1 - 2 billion worth of damage in the United States annually. They can be triggered by humans or by nature. It has been widely recognized that rainfall is one of the major causes of slope instability and failure. Slope remediation and stabilization efforts can be costly. An early warning system is a suitable alternative and can save human lives. In this project, an early warning system was developed for a 40-foot-high cut slope on the island of Hawaii. To achieve the objective, subsurface investigations were performed and undisturbed samples were collected. For the purpose of unsaturated soil testing, new testing apparatuses were developed by modifying the conventional oedometer and direct shear cells. The unsaturated soil was characterized using two separate approaches and, later, the results were discussed and compared. The slope site was instrumented for the measurement of suction, water content, displacement, and precipitation. The collected climatic data along with the calibrated hydraulic parameters were used to build an infiltration-evapotranspiration numerical model. The model estimations were compared with the field measurements and showed good agreement. The verified model was used to determine the pore-water pressure distribution during and after a 500-years return storm. Later, the pore-water pressure distribution was transferred to a slope stability software and used to study the slope stability during and after the storm. Based on a 2D slope stability analysis, the slope can survive the 500-year storm with a factor of safety of 1.20. Instrument threshold values were established for water content sensors and tensiometers using a traffic-light-based trigger criterion.
  • Resource limitation of autotrophs and heterotrophs in boreal forest headwater streams

    Weaver, Sophie Alden; Jones, Jeremy B.; Leigh, Mary Beth; Ruess, Roger W. (2019-12)
    In stream biofilms, autotrophs and heterotrophs are responsible for the majority of in stream nutrient transformations. In boreal forest catchments, discontinuous permafrost can lead to variation in nutrient and energy resources, which can control competition for nutrients between autotrophs and heterotrophs within these biofilms. I was interested in determining what resources control nutrient utilization by autotrophs and heterotrophs in headwater streams in the boreal forest of interior Alaska. I hypothesized that the outcome of competition between autotrophs and heterotrophs for inorganic nutrients would be dependent on the availability of (i) organic carbon, (ii) light, or (iii) inorganic nutrients. To measure resource limitation and competition at both patch and reach scales, I deployed nutrient diffusing substrata and conducted nutrient uptake experiments in streams along a permafrost gradient at the Caribou-Poker Creeks Research Watershed in interior Alaska. At the patch scale, autotrophs were light and nutrient limited, whereas heterotrophs were carbon and nutrient limited, and at the reach scale, light had the largest influence on nutrient uptake. Heterotrophs exhibited a larger response to nutrient enrichment when stream ambient carbon stocks were more bioavailable. Autotrophic biomass and productivity was suppressed when labile carbon was available to heterotrophs, suggesting that heterotrophs outcompete autotrophs for nutrients when a labile carbon source is introduced. The positive responses to nutrient and carbon additions suggest that the hypothesized increased nutrient and carbon exports into fluvial networks with permafrost degradation will impact biofilm structure and function, with the potential to influence nutrient export and stream ecosystem function downstream.
  • Quliriuralta (Lets keep telling stories): pace model with traditional Yup'ik storytelling in a second grade dual language classroom

    Wassilie, Irene M.; Siekmann, Sabine; Martelle, Wendy; Patterson, Leslie; Samson, Sally (2019-12)
    This research was conducted in a setting where the students are losing their Indigenous language. It is centered around the retention and revitalization of the Yugtun language. The goal of the research was to gain insights into how second graders in a dual language enrichment school constructed meaning and focus on form in their classroom. The instructional model employed as part of this investigation is the PACE Model, which is a story-based approach to teaching grammar through focus on form with an emphasis on meaning making. The model is consistent with Indigenous oral storytelling, cultural values, traditions and expectations. The study involves myself and fourteen second graders in Napaskiak, Alaska. ZJW Memorial School is one of 28 schools in the Lower Kuskokwim School District. Of these fourteen students, only one spoke Yugtun as his first language. The others were immersed into Yugtun as a second language. I implemented the PACE approach over the course of 25 days. Data was gathered through field notes, student artifacts, video and audio recordings. The data reveals that meaning making and building background knowledge can be a challenge for both teacher and students. It also reveals that the teacher should be implementing multimodal approaches to build comprehensible input so that students may produce output in the target language.
  • Effects of wind energy utilization on long-run fuel consumption in remote Alaska microgrids

    Vaught, Laura K.; Little, Joseph; Baek, Jungho; Pride, Dominique (2019-12)
    This paper presents an empirical analysis of the long-run reduction in diesel fuel consumption driven by wind energy utilization in remote Alaska electrical grids. Models control for other fuel consumption determinants including customer base and transmission and distribution system efficiency. Fourteen rural communities that integrated wind energy into their diesel powered electrical grids are analyzed within a dynamic panel framework using monthly utility data spanning sixteen years, from 2001 to 2017. An auto-regressive distributed lag approach is taken to address cointegration and presence of a unit root in the data. Long-run parameters are estimated for the full dataset as well as for four sub-samples to compare impacts on microgrids with high and low average renewable utilization and with large and small customer bases. Results indicate that fuel consumption is reduced by an estimated 68 gallons on average for each one percent increase in wind energy penetration on the electricity grid. Beyond 30% average penetration, however, additional wind energy generation leads to increased fuel consumption as turbine curtailment methods must be employed to maintain grid stability, indicating that this is a fuel-offset constraint point in low and medium penetration wind-diesel hybrid systems. High penetration-capable wind-diesel systems with energy storage capabilities may allow utilities to increase utilization rates beyond this threshold to capture additional fuel savings and carbon emissions offset.
  • Regional distribution, life history, and morphometry of spawning stage Capelin Mallotus villosus

    Ressel, Kirsten N.; Sutton, Trent M.; Bell, Jenefer L.; Seitz, Andrew C. (2019-12)
    Capelin Mallotus villosus is a forage fish that is integral to many Arctic and subarctic marine food webs, but is less thoroughly studied outside the Atlantic Ocean. The goal of this research was to study spawning Capelin in data-poor areas, particularly in waters off the coast of Alaska and the western Canadian Arctic, to enrich baseline data and allude to intraspecies diversity. Chapter one examined the distribution and life history of spawning Capelin in Norton Sound, Alaska, by conducting aerial surveys, collecting sediment samples to characterize beach spawning habitats, and identifying biological attributes of spawners (e.g., body size, age, fecundity, etc.). Chapter two used a geometric morphometric approach (i.e., relative warps) and multiple statistical techniques (i.e., relative warp analysis, Procrustes analysis of variance, estimates of morphological disparity, and canonical variates analysis) to differentiate among and within putative populations of spawning Capelin in the western Canadian Arctic, Newfoundland, Canada, and Alaska. Spawning Capelin in Norton Sound portrayed similar behaviors, occupied similar beach habitats, and encompassed a similar range in biological attributes as fish observed in other regions throughout this species' geographic distribution. However, average spawner body size, age, fecundity, and morphometry differed among regions. These results suggest that Capelin exhibit some similarities in spawning behavior and habitat use across their geographic distribution, but may exhibit population-specific differences in biological attributes among and within regions.
  • Impacts of storm on sea ice: from case study to climate scale analysis

    Peng, Liran; Zhang, Xiangdong; Collins, Richard; Fochesatto, Javier; Polyakov, Igor (2019-12)
    Recent studies have shown that intense and long-lasting storms potentially facilitate sea ice melting. Under the background of extratropical storm tracks poleward shift, significant reductions of Arctic sea ice coverage, and thinning of sea ice thickness over the last several decades, a better understanding on how storms impact sea ice mass balance is obviously of great importance to better predict future sea ice and the Arctic climate changes. This thesis presents a multi-scale study on how storms impact sea ice, consisting of three different parts of the effort. In the first part, we examined the impacts of the 2016 summer intense storm on sea ice changes over the Chukchi Sea using ship-borne observations. The results show that the intense storm can accelerate ice melt through enhanced upper-ocean mixing and upward heat transport. The satellite-observed long-term sea ice variations potentially can be impacted by many factors. In the second part, we first explore key physical processes controlling sea ice changes under no-storm condition. We examined and compared results from 25 sensitivity experiments using the NCAR's Community Earth System Model (CESM). We found that sea ice volume, velocity, and thickness are highly sensitive to perturbed air-ice momentum flux and sea ice strength. Increased sea ice strength or decreased air-ice momentum flux causes counter-clockwise rotation of the transpolar drift, resulting in an increase in sea ice export through Fram Strait and therefore reduction of the pan-Arctic sea ice thickness. Following four tracers released over the Arctic, we found the sea ice thickness distributions following those tracers are broader over the western Arctic and becomes narrower over the eastern Arctic. Additionally, thermodynamic processes are more dominant controlling sea ice thickness variations, especially over periphery seas. Over the eastern Arctic, dynamic processes play a more important role in controlling sea ice thickness variation. Previous studies show that thin ice responds to external perturbations much faster than the thick ice. Therefore, the impacts of storms on sea ice are expected to be different compared with the western/eastern Arctic and the entral/periphery seas. In the third part, we conduct a new composite analysis to investigate the storm impact on sea ice over seven regions for all storms spanning from 1979 to 2018. We focused on sea ice and storm changes over seven regions and found storms tend to have different short-term (two days before and after storm passage), mid-term (one-two weeks after storm passage), and long-term (from 1979 to 2018) impact on sea ice area over those regions. Over periphery seas (Chukchi, East Siberian, Laptev, Kara, and Barents Seas), storms lead to a short-term sea ice area decrease below the climatology, and a mid-term sea ice increase above the climatology. This behavior causes sea ice area to have a small correlation with the storm counts from 1979 to 2018, which suggest that storms have a limited long-term impact on sea ice area over periphery seas. Both the short term and mid-term storm impacts on sea ice area are confined within a 400 km radius circle with maximum impacts shown within a 200 km radius circle. Storms over the western Arctic (Chukchi, East Siberian, and Laptev Seas) have a stronger short-term and mid-term impact on sea ice area compared with the Eastern Arctic (Barents and Kara Seas). Storms over both Atlantic and Pacific entrance regions have a small impact on sea ice area, and storms over the Norwegian, Iceland, and Greenland Seas have the smallest impact on the sea ice area. Compared to the periphery seas, storms tend to have a stronger long-term impact on sea ice area over the central Arctic. The correlation coefficients between the storm count and sea ice area exceed 0.75.
  • Carbon flux and particle-associated microbial remineralization rates in the northern Bering and southern Chukchi seas

    O'Daly, Stephanie Hicks; McDonnell, Andrew M. P.; Hardy, Sarah M.; Johnson, Mark A. (2019-12)
    It has been hypothesized that climate change will reduce the strength and episodic nature of vernal phytoplankton blooms, increase heterotrophy of microbes and zooplankton, and weaken the tight coupling between pelagic and benthic production that is characteristic of Arctic continental shelves. As a part of the Arctic Shelf Growth, Advection, Respiration, and Deposition rates measurement (ASGARD) project, I quantified sinking particle fluxes and incubated sinking particles to measure the rate of microbial respiration associated with those particles. These measurements were used to characterize the strength of the pelagic-benthic connection. After a record-breaking year of warm temperatures and low-ice conditions in the northern Bering and southern Chukchi Seas, we observed massive vernal fluxes of sinking particulate organic carbon, ranking amongst the highest observed in the global oceans. Moreover, low rates of particle-associated microbial respiration indicate negligible recycling of sinking organic matter within the water column. These results suggest that the strength of the biological carbon pump may be maintained or enhanced in a warming Arctic, supporting strong benthic and upper trophic level productivity and carbon export.
  • Laboratory investigation of infiltration process of nonnewtonian fluids through porous media in a non-isothermal flow regime for effective remediation of adsorbed contaminants

    Naseer, Fawad; Misra, Debasmita; Metz, Paul; Awoleke, Obadare; Najm, Majdi Abou (2019-12)
    Contamination of soil and groundwater have serious health implications for man and environment. The overall goal of this research is to study a methodology of using nonNewtonian fluids for effective remediation of adsorbed contaminants in porous media under nonisothermal flow regimes. Non-Newtonian fluids (Guar gum and Xanthan gum solutions) provide a high viscous solution at low concentration and these fluids adjust their viscosities with applied shear rate and change in temperature. Adjustment of viscosity with an applied rate of shear is vital for contaminant remediation because non-Newtonian shear thinning fluids can penetrate to low permeability zones in subsurface by decreasing their viscosities due to high shear rates offered by low permeability zones. The application of non-Newtonian shear thinning fluids for contaminant remediation required the improvement in understanding of rheology and how the factors such as concentration, temperature and change in shear rate impacted the rheology of fluids. In order to study the rheology, we studied the changes in rheological characteristics (viscosity and contact angle) of non-Newtonian fluids of different concentrations (i.e., 0.5g/l, 1g/l, 3g/l, 6g/l and 7g/l) at different temperatures ranging from 0 ºC to 30 ºC. OFITE model 900 viscometer and Tantec contact angle meter were used to record the changes in viscosity of fluids for an applied range of shear rate (i.e., 17.02 s⁻¹ to 1021.38 s⁻¹) and contact angles, respectively, for different concentrations of non-Newtonian fluids. Understanding the flow characteristic of non-Newtonian fluids under low temperature conditions could help in developing methods to effectively remediate contaminants from soils. Results of rheological tests manifested an increase in the viscosity of both polymers with concentration and decrease in temperature. Mid (i.e., 3g/l) to high (i.e., 6g/l and 7g/l) concentrations of polymers manifested higher viscosities compared to 0.5g/l for both polymers. Flow of high viscous solutions required more force to pass through a glass-tube-bundle setup which represented a synthetic porous media to study the flow characteristic and effectiveness of Newtonian and non-Newtonian fluids for contaminant remediation. Low concentrations of 0.5g/l were selected for flow and remediation experiments because this concentration can flow through porous media easily without application of force. The 0.5g/l of Xanthan gum and de-ionized water were used to conduct the infiltration experiments to study the flow characteristics of Newtonian and non-Newtonian fluids at 0.6°C, 5°C and 19°C in synthetic porous media. Infiltration depth of both Newtonian and non-Newtonian fluids would decrease with the decrease in temperature because of the change in their properties like dynamic viscosity, density and angle of contact. The result of comparison of Newtonian and non-Newtonian fluids showed water to be more effective in remediating a surrogate adsorbent contaminant (Dichlobenil) from the synthetic porous media at 19°C. This result was counter-intuitive to what we began with as our hypothesis. However, it was also observed later that 0.5 g/l concentration of Guar gum behaved more like a Newtonian fluid and 0.5 g/l concentration of Xanthan gum had not shown strong non-Newtonian behavior compared to higher concentrations of Xanthan gum. Hence more analysis needs to be done to determine what concentration of non-Newtonian fluid should be more effective for remediation.
  • Pairwise comparisons of shrub change across alpine climates show heterogeneous response to temperature in Dall's Sheep range

    Melham, Mark; Valentine, Dave; Panda, Santosh; Brinkman, Todd (2019-12)
    Encroachment of woody vegetation into alpine and high latitude systems complicates resource use for specialist wildlife species. We converted Landsat imagery to maps of percent shrub cover in alpine areas of Dall's sheep (Ovis dalli dalli) range. We then compared percent cover to interpolated climate data to infer drivers of shrub change between the 1980s and 2010s and determine if that change is occurring at different rates in climatically distinct alpine areas. We identified areas spatially interconnected by their mean July temperature intervals and compared their rates of shrub change, finding net rates of shrub growth were higher at temperatures notably above shrub growing season minimums. Along a climatic gradient, high precipitation areas had highest net shrub change, Arctic areas followed, while alpine areas of interior Alaska and the cold Arctic showed the least amount of net shrub change at these higher temperatures. Despite the requirement of higher temperatures for shrub growth, temperature and net shrub change displayed different relationships across the range wide climatic gradient. In areas of rapid climate warming, such as the Arctic and cold Arctic, the linear correlation between shrub change and temperature was highest. In the high precipitation areas where temperatures have been largely above growing season minimums during the study period, precipitation had the strongest linear correlation with shrub change. High latitude studies on shrub change focus primarily on expansion in the Arctic, where increased greening trends are linked to higher rates of warming. We provide the broadest climatic examination of shrub change and its drivers in Alaska and suggest shrub expansion 1) occurs more broadly than just in areas of notable climate warming and 2) is dependent on different environmental factors based on regional climate. The implications for Dall's sheep are complicated and further research is necessary to understand their adaptive capacity in response to this widespread vegetative shift.
  • Retrodirective phased array antenna for nanosatellites

    Long, Justin W.; Thorsen, Denise; Kegege, Obadiah; Hawkins, Joseph; Mayer, Charles (2019-12)
    This thesis presents a S-band phased array antenna for CubeSat applications. Existing state-of the-art high gain antenna systems are not well suited to the majority of CubeSats, those that fall within the 1U (10 cm x 10 cm x 10 cm) to 3U (10 cm x 10 cm x 30 cm) size ranges and in Low Earth Orbit (LEO). The system presented in this thesis is designed specifically to meet the needs of those satellites. This system is designed to fit on the 1U face (10 cm x 10 cm) of a CubeSat and requires no deployables. The use of beamforming and retrodirective algorithms reduces the pointing requirements of the antenna, easing the strict requirements that high gain antennas typically force on a CubeSat mission. Additionally, this design minimizes volume and uses low cost Commercial-off-the-Shelf (COTS) parts. This thesis discusses the theoretical background of phased array theory and retrodirective algorithms. Analysis are presented that show the characteristics and advantages of retrodirective phased antenna systems. Preliminary trade studies and design analyses show the feasibility and expected performance of a system utilizing existing COTS parts. The preliminary analysis shows that an antenna system can be achieved with ≥8.5 dBi of gain, 27dB of transmitted signal gain, 20% Power Added Efficiency (PAE) within a 1 W to 2 W power output, and an 80° effective beamwidth. Simulation results show an example antenna array that achieves 8.14 dBi of gain and an 82° effective beamwidth. Testing results on a prototype of the front-end electronics show that with minimal calibration, the beamforming and scanning error can be reduced to 5°. The power consumption and signal gain of the electronics is also verified through testing. The CubeSat Communications Platform, a CubeSat mission funded through the Air Force Research Laboratory is in Phase A design to demonstrate this antenna system, along with other experimental payloads. This thesis includes a discussion of interface control, mission requirements, operations, and a recommended experiment sequence to test and verify the antenna system on orbit.
  • Phylogenetic relationships within the Western United States species of Lepidium l.

    Lichvar, Robert W.; Laursen, Gary; Duffy, Lawrence; Dorn, Robert; Wolf, Paul (2019-12)
    The genus Lepidium L. is one of two global genera in the Brassicaceae. The genus has been arranged by species (geographic regions) worldwide, but no formal levels below the genus are recognized. Recent efforts to evaluate phylogenetic relationships have been performed at the global scale for about 20 percent of the species in the genus. The genus is recognized as having subtle and variable morphological characteristics to define species limits. Several nuclear and chloroplast DNA methods have been used to construct phylogenetic relationships within the genus. Incongruences between various phylogenetic trees indicate likely hybridization and/or hybrid origin of multiple species and a genus blurred with a reticulate evolutionary past. Internal Transcribed Spacer (ITS) ribosomal DNA (rDNA) sequences were developed here and combined with other ITS sequences on Genbank for other North American species of Lepidium. Two phylogenetic trees were developed, one comparing North American and another dominated by Intermountain West species. Results of a limited Intermountain Lepidium phylogenetic tree were compared to a cladistic tree developed from 123 morphological traits for select species of Lepidium from the western United States. A comprehensive ITS tree was developed to evaluate species relationships in the genus throughout this region. Ploidy levels of 22 taxa of Intermountain species of Lepidium were evaluated to assess whether ploidy levels were associated with any geographic or morphologic patterns within the group. The results show closely related species and varieties with several ploidy levels, but are lacking any relationships to morphological features. Neither ITS nor ploidy levels provided a clear understanding into the current taxonomic treatment of the many faint morphologically different taxa in the group. But Intermountain Lepidium, as a geographic group and clade, is distinct from other west coast members in the genus. The species most associated with all the radiant speciation, and the least understood, is L. montana.
  • Host-parasite ecophysiology of overwintering

    Larson, Don J.; Barnes, Brian; O'Hara, Todd; Sikes, Derek; Wipfli, Mark (2019-12)
    To survive extreme winters, parasites must overwinter either in a host, as free-living larvae, or be reintroduced yearly through migratory hosts. This thesis examines interrelations between host parasite overwintering physiology and behavior in Alaska between the trematode Ribeiroia ondatrae and their host, wood frogs (Lithobates sylvaticus). The first chapter examines overwintering physiology and behavior of wood frogs in the field. The second chapter creates a laboratory method for determining physiological responses of wood frogs to environmental transitions from summer to fall. The third chapter examines if and how R. ondatrae survive within a frozen wood frog. Free-living wood frogs investigated over two winters in Fairbanks, AK remained frozen for up to 7 months and survived temperatures as low as -18°C, values much more extreme than those previously reported (Chapter 1). Alaskan wood frogs also synthesized and released approximately one order of magnitude greater concentrations of cryoprotectant (glucose) in multiple tissues than levels previously reported. Wood frogs in the field did not experience the same slow and continuous cooling that researchers routinely subject frogs to under experimental conditions. Instead they cooled at rates of up to -1.5°C h⁻¹ for short periods in a diurnal freeze-thaw pattern repeated over one to three weeks until remaining frozen for the rest of winter. Since wood frogs only produce glucose at the initiation of freezing, I hypothesized that freeze-thaw cycling within hibernacula allowed for incremental increases of glucose resulting in higher concentrations in field wood frogs than found in laboratory frozen wood frogs. I compared patterns of diurnal freeze-thaw cycling with the standard laboratory freezing protocols for wood frogs. Wood frogs that experienced multiple freeze-thaw events responded with significant increases in glucose concentration in liver, leg, and heart tissues at each freezing with no significant losses in glucose with each following thaw period (Chapter 2). This incremental increase in glucose within wood frogs may also assist in parasite survival. Trematode metacercariae may be absorbing host glucose and using this cryoprotectant to enhance their survival (Chapter 3). This result provides evidence that host physiology in winter may both hinder (through freezing) and facilitate (through cryoprotectant production) parasite survival.
  • Foraging tactics of humpback whales feeding near salmon hatchery-release sites in Southeast Alaska

    Kosma, Madison M.; McPhee, Megan V.; Straley, Janice M.; Szabo, Andrew R.; Wooller, Matthew J. (2019-12)
    Increases in the humpback whale (Megaptera novaeangliae) population have generated considerable interest in understanding the foraging habits of these large marine predators in the Gulf of Alaska. Globally, humpback whales are classified as generalist predators but are known to exhibit localized differences in diet. Intensified predation pressure is of particular concern to resource managers, who have observed whales feeding at juvenile hatchery salmon release sites in Southeast Alaska. We assessed the diets and behavioral tactics of humpback whales foraging near Hidden Falls Hatchery release sites (in Chatham Strait, 2016 to 2018) to better understand their predatory effects on juvenile hatchery-reared salmon. We used skin biopsies, prey sampling, and stable isotope analysis to estimate whales' diet composition. Aerial footage and photographic sequences were used to assess the foraging tactics used on this prey source. We observed three individual whales repeatedly feeding on juvenile hatchery-reared salmon, and we were able to sample them multiple times over a period spanning shifts in diet. Overall, the diets of these whales were higher trophically than other humpback whales foraging in the area, even before feeding on juvenile hatchery salmon started. These hatchery-feeding whales may be generally more piscivorous than other whales, which focused on planktivorous prey. Our repeat sampling, in conjunction with scheduled introductions of a novel prey source, provided a semi-controlled feeding experiment that allowed for incorporation and turnover rate estimates from humpback whale tissue in a way that was not previously possible for large, free-ranging cetaceans. Finally, during the course of this study we discovered an undescribed feeding tactic employed by hatchery-associated whales. We observed the use of solo bubble-nets to initially corral prey, followed by calculated movements to establish a secondary boundary with the pectoral fins that further condensed prey and increased foraging efficiency. Our study provided the first empirical evidence for what we describe as "pectoral herding". This work deepens our knowledge about humpback whale foraging ecology, how this innovative species is able to exploit newly available prey, and to what extent they feed on commercially valuable hatchery salmon.
  • Classification and signal processing of radio backscatter from meteors

    Klemm, Jared; Thorsen, Denise; Bossert, Katrina; Collins, Richard; Mayer, Charlie (2019-12)
    Ground-based radar systems are routinely used to detect the trails of ionized particles that are formed by meteoroids falling through Earth's atmosphere. The most common use for these meteor radar systems is for atmospheric wind studies of the mesosphere and lower thermosphere (80-100 km altitude). Because these meteor trails are embedded in the background winds of the middle atmosphere, atmospheric winds in that region can be measured by observing the radial velocities of the trails. There has also been a considerable amount of research over the last few decades into estimation of neutral atmospheric temperatures using the measured decay time of meteor trails. Several methods exist for estimating atmospheric temperature using meteor radar observations, but there are limitations to these approaches. This thesis focuses on examining aspects of meteor radar signal and data processing, specifically interferometry and echo classification. Interferometry using the measured signal phase differences between antennas allows for the location of meteor trails to be unambiguously determined. Classification schemes are used to identify which echoes can be modeled as underdense meteors, overdense meteors, or other potentially non-meteor echoes. Finally, based on the proposed classification scheme, this thesis examines several temperature estimation methods for both underdense and overdense echoes and discusses the current issues in this area. Preliminary results from a newly installed meteor radar at Poker Flat Research Range are also presented.
  • Explorations of intergenerational healing, resilience, and post-traumatic growth by helpers and healers on the Blackfeet Nation

    Hoyt, Tyler J.; Gifford, Valerie M.; Whipple, Jason; Topkok, Sean; David, Eric John (2019-12)
    This project explored intergenerational healing, resilience, and post-traumatic growth within the context of the Blackfeet Nation in Montana, the roles of helpers and healers in this setting, and community experiences of familial trauma and the idiosyncratic healing and resilience processes according to their worldview. The central goal of this study was to provide a contemporary public narrative surrounding healing and resilience as these topics related to historical and intergenerational trauma in this specific community. This exploratory study was composed of the narratives of 14 co-participants working as helpers and healers on the Blackfeet Nation. Indigenous narrative and a cosmic relationality were honored and a phenomenological method of Gadamerian hermeneutics was utilized. Seven central themes arose in the process of data analysis including Spirituality, Trauma, Healing, Resilience, Helping Role, Community, and Blackfeet Worldview. Co-participants explored contemporary experiences of collective intergenerational trauma of those they served as well as personal and familial processes of healing and resilience. The centrality of spirituality, cultural immersion and personal cultural identity were discussed as aspects of intergenerational healing and resilience. A holistic and culturally idiosyncratic understanding of personal and intergenerational healing was emphasized including spiritual, emotional, mental, and physical modes of healing. Patterns of healing experienced collectively and synergistically within family systems and between community members were also identified.
  • Validating a GPS collar-based method to estimate parturition events and calving locations for two barren-ground caribou herds

    Hepler, Joelle D.; Griffith, Brad; Falke, Jeff; Roach, Jen (2019-12)
    In remote landscapes, it is difficult and expensive to document animal behaviors such as location and timing of parturition. When aerial surveys cannot be conducted as a result of weather, personnel or fiscal constraints, analyses of GPS collar movement data may provide an alternate way to estimate parturition rates and calving ground locations. I validated two methods (population-based method and individual-based method), developed to detect calving events of sedentary woodland caribou, on multiple years of data for two different migratory barren-ground caribou herds in Alaska, the Porcupine and Fortymile herds. I compared model estimates of population parturition rates, individual calving events, calving locations and calving dates to estimates from aerial survey data for both herds. For the Porcupine herd we also compared model estimates of annual calving ground sizes and locations of concentrated calving area centroids to those found with aerial survey. More years of data would be required for additional statistical power but for both the Porcupine and Fortymile herds, we found no significant difference between the population-based and individual-based method in: 1) individual classification rate accuracy (0.85 vs. 0.88, respectively; t = -7, P = 0.09, df = 1 and 0.85 vs. 0.83, respectively; t = 0.46, P = 0.69, df = 2) or 2) annual average distance from aerial survey calving locations (8.9 vs. 7.8 km, respectively; t = 0.16, P = 0.90, and 5.2 vs. 3.7 km, respectively; t = 1.03, P = 0.20). Median date of calving was estimated within 0-3 days of that estimated by aerial survey for both methods. Population parturition rate estimates from aerial survey, the population-based and individual-based methods were not significantly different for the PCH or FCH (0.91, 0.88 and 0.95, respectively; F = 0.67, P = 0.60, df = 2, and 0.83, 0.83 and 0.96, respectively; F = 3.85, P = 0.12, df = 2). Ultimately, more years of data would be required to support or reject the lack of significant differences between methods that we observed.
  • Paving the road to college: impacts of Washington State policy on improving equitable participation in dual credit courses

    Hanson, Havala; Vinlove, Amy; McIntyre, Julie; Adams, Barbara; Mazzeo, Christopher; Wong, Kenneth (2019-12)
    This dissertation evaluates early impacts of a state policy to increase participation in dual credit courses in Washington state through subsidizing the cost of college credits for underrepresented rural and low-income students, and through extending eligibility to earn dual credit to students in grade 10. This study evaluates both aspects of the policy, with emphasis on the impacts for underrepresented rural and low-income students, students of color, and English learners. It employs quasi-experimental designs to estimate the impact of the policy on intended outcomes. The study finds mixed early impacts of the policy. While no effects were found for students attending schools near the cutoffs for eligibility for tuition subsidies, promising evidence emerged on the policy's impact on participation in dual credit among students in grade 10. The findings can provide policymakers with early evidence of the policy's effects, identify places where implementation may be strengthened, and serve as a blueprint for ongoing monitoring of the policy's impact and similar evaluations of dual credit policies nationwide.
  • Development of a Computer Vision-Based Three-Dimensional Reconstruction Method for Volume-Change Measurement of Unsaturated Soils during Triaxial Testing

    Zhang, Xiong; Xia, Xiaolong (2019-10)
    Problems associated with unsaturated soils are ubiquitous in the U.S., where expansive and collapsible soils are some of the most widely distributed and costly geologic hazards. Solving these widespread geohazards requires a fundamental understanding of the constitutive behavior of unsaturated soils. In the past six decades, the suction-controlled triaxial test has been established as a standard approach to characterizing constitutive behavior for unsaturated soils. However, this type of test requires costly test equipment and time-consuming testing processes. To overcome these limitations, a photogrammetry-based method has been developed recently to measure the global and localized volume-changes of unsaturated soils during triaxial test. However, this method relies on software to detect coded targets, which often requires tedious manual correction of incorrectly coded target detection information. To address the limitation of the photogrammetry-based method, this study developed a photogrammetric computer vision-based approach for automatic target recognition and 3D reconstruction for volume-changes measurement of unsaturated soils in triaxial tests. Deep learning method was used to improve the accuracy and efficiency of coded target recognition. A photogrammetric computer vision method and ray tracing technique were then developed and validated to reconstruct the three-dimensional models of soil specimen.
  • Modeling volcanic ash and sulfur dioxide with the Weather Research Forecasting with Chemistry (WRF-Chem) model

    Egan, Sean D.; Cahill, Catherine; Stuefer, Martin; Webley, Peter; Lopez, Taryn; Simpson, William (2019-12)
    The Weather Research Forecasting with Chemistry (WRF-Chem) model is capable of modeling volcanic emissions of ash, sulfur dioxide and water vapor. Here, it is applied to eruptions from three volcanoes: the 2008 eruption of Kasatochi Volcano in Alaska, the 2010 eruption of Eyjafjallajökull in Iceland and the 2019 eruption of Raikoke in the Kurile Islands. WRF-Chem's ability to model volcanic emissions dispersion is validated through comparison of model output to remote sensing, in situ and field measurements. A sensitivity of the model to modeled plume height is discussed. This work also modifies the base WRF-Chem code in three ways and studies the effects of these modifications. First, volcanic ash aggregation parameterizations are added covering three modes of particle collisions through Brownian motion, differential settling and shear. Second, water vapor emissions from volcanic eruptions are added and coupled to the new aggregation scheme. The effects of these changes are assessed and found to produce volcanic ash concentrations in agreement with in situ measurements of plume concentrations and field measurements of tephra fallout. Third, the model is adapted to include multiple model initializations such that each is perturbed by selecting between two volcanic ash particle sizes and five initial plume heights. This modified WRF-Chem is nested in an application program interface that enables a new, automated, near real-time capability. This capability is assessed and the feasibility of its use as an augmenting tool to current operational VATD models is commented upon.
  • Engineering education professional development for teachers in the Delta Greely School District

    Dougherty, Jennifer; Kaden, Ute; Thorsen, Denise; Larson, Angela (2019-12)
    Over the last two decades engineering has become a new focus in many science curricula, in part due to the emphasis on STEM (science, technology, engineering, and math) education. Most teachers lack training or education in engineering and are not adequately prepared to implement effective engineering education. This research identifies the needs and constraints of one district, the Delta Greely School District (DGSD), in Delta Junction, AK (approximately 750 students district-wide). Surveys were distributed to fifty teachers and five administrators to gather information on attitudes and beliefs surrounding engineering education. Focus groups were conducted with teachers and administrators to better understand the needs of the teachers and the district as well as the perceived obstacles that currently limit engineering education in the classroom. The results were used to create recommendations for professional development to improve and increase engineering education in the district's K-5 classrooms. The final recommendations focus on a professional development plan and professional development delivery modes. Results of the study support two levels of professional development: one introductory level for teachers unfamiliar or not comfortable with engineering education and one for teachers who are comfortable with the subject and would like to improve their teaching. It was also determined that specific teaching resources (i.e., lesson plans and curricular material) should be part of professional development, and that professional development solution should be designed to complement the specific district-provided resources and curricula.

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