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.

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.

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.

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.

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.

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.

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.

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.

This meta-synthesis explores the correlation between language acquisition and learning. Children who are bilingual have advantages and disadvantages to how they learn. When research first started on this idea, common opinion was that it was a disadvantage to be bilingual. However, as research has progressed more advantages than disadvantages of being bilingual have been found. Furthermore, new ways children can learn language have appeared. Options can include but are not limited to parents and guardians, an immersion program, and/or a dual/multi-language program. An important factor of language acquisition is for children to be fluent in one language before they learn a second language. Children that do not have a firm grasp of their first language combine two language patterns and create a different language. The combining of languages causes them to have challenges throughout their education.

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.