Now showing items 1-20 of 10117

    • Working with Individuals with Fetal Alcohol Spectrum Disorders: A Meta-Synthesis

      Rehmer, Shelby (University of Alaska Southeast, 2014)
      This meta-synthesis of the literature on working with individuals with Fetal Alcohol Spectrum Disorders (FASD) examines the characteristics of individuals with FASD and the need for supports and services for these individuals in the classroom. There are behavior characteristics unique to FASD and these behaviors coupled with sensory processing deficits lead to distinctive challenges for individuals with FASD. Early identification, supports and services are critical to address challenges for individuals with FASD in the classroom, yet are often unavailable or unidentified.
    • Even in Arcadia: stories

      Wood, Rebecca N.; Farmer, Daryl; Johnson, Sara; Schell, Jennifer (2021-05)
      Even in Arcadia: Stories is a short story collection that follows adolescent and young adult women as they navigate growing up and growing out of the spaces they inhabit. Set in the American southwest, specifically unnamed suburban and rural cities of Arizona, the collection challenges the culturally popular narratives that surround the West-- the idealized cowboy, rugged individualism, and conquest of nature. Drawing on long-standing myths, serialized TV shows, and classic literature, the collection asks the reader to evaluate the stories they consume and are willing to take as truth. The stories range from realistic to speculative, employing horror and surrealistic elements as they descend into a sort of hellscape that draws on natural elements of desert landscapes juxtaposed against urban spaces. The collection focuses on gender, adolescence, and trauma set in the aftermath of the 2008 recession and the decline of small-town America from the perspective of youth.
    • The development and initial testing of the vertical comet assay, a novel technique for the study of DNA damage and repair

      Williams, Robert T. D.; Pdlutsky, Andrej; Chen, Cheng-fu; Drew, Kelly (2021-05)
      Gene-specific repair is the idea that certain segments of the genome repair at a faster rate than others. This idea, if demonstrated with adequate evidence, would have large implications for the field of biology as a whole, with special significance for the fields of oncology, gerontology, and molecular and cell biology. The concept of gene-specific repair is not new, with the earliest references in the literature dating back to 1985, and there is a small volume of evidence derived over the years. However, the evidence generated so far is not enough to conclusively prove the existence of gene-specific DNA repair. Generally, the reason for the lack of evidence is that currently available assays and techniques are not adequate for the study of gene-specific repair on a large scale as the techniques that are available require a great deal of time, funding, and skill to generate a reliable and conclusive data set for a single gene, let alone the entire genome. The vertical comet technique described here-in is a response to the perceived need for a robust and relatively high-throughput technique for the study of gene-specific DNA repair. In the traditional comet assay, cells are fixed in agarose gel. Electrophoresis is performed, following several treatment steps, to create a ball of nuclear material embedded in the agarose gel with a 'tail' of smaller pieces of nominally damaged DNA extending to one side. The vertical comet captures this tail DNA in a buffer, allowing for its further analysis with processes such as quantification, PCR/qPCR, and sequencing. The capture of the tail DNA not only makes genespecific repair studies possible, it also allows the vertical comet to fulfill the role of the traditional comet assay with a number of advantages - a reduction in human bias, a reduction in labor-hours required for work, and a reduction in inter-lab variability of results.
    • Exploring the use of machine learning for daily fire growth prediction in Alaska

      White, James; Walsh, John; Thoman, Richard; Bhatt, Uma (2021-05)
      Wildfire is a natural but often hazardous part of the Alaskan ecosystems. Physically based wildfire models range from simple relationships used for rapid, in-situ fire behavior analysis to complex weather models used for prediction over several days and weeks. Physical models in Alaska, however, often struggle to integrate weather forecast information to make predictions beyond just a few days. The random forest model explored here is able to leverage an array of variables to identify days of enhanced and reduced satellite fire detections. Peaks and lulls in activity are accurately identified, though exact magnitudes are often incorrect, especially when wildfire suppression efforts occurred. This study emphasizes the use of reanalysis weather variables in addition to antecedent fire activity, highlighting the usefulness of variables like vapor pressure deficit for use in quantitative prediction. By applying weather forecast data, the model generated simulated wildfire forecasts. These forecasts show some success at identifying peaks and lulls in fire activity. Effective lead time varied widely ranging between 1 and 10 days, mostly dependent on the weather model performance. By providing specific timing and using real ensemble forecasts for medium term prediction, a model likes this fills a potential open niche in fire predictive services. Machine learning may be especially useful for its relative efficiency and ease of automation.
    • Salmonid distribution models to support restoration planning across the fragmented Chehalis River basin, WA

      Walther, Eric J.; Westley, Peter; Zimmerman, Mara; Falke, Jeffrey; Seitz, Andrew (2021-05)
      Understanding the factors that influence the distribution of species through time and across space is a fundamental goal of ecology and crucial information needed to effectively manage and recover populations. Anthropogenic fragmentation of habitat disrupts ecological processes and is an on-going threat to species persistence across taxa. River ecosystems are particularly vulnerable to disruptions in connectivity and are the focus of extensive restoration efforts and financial investment. For example, over $300 million/year is invested towards restoration in the Columbia River basin. However, restoration is often impeded by knowledge gaps in distribution that can result in omitting locations that would benefit from restoration. For mobile species within dendritic freshwater networks, the boundary that demarcates the total quantity of available habitat can be defined by the upper limit of occurrence (ULO) and is a useful metric for assessing the extent of habitat to consider for restoration. The first goal of this work was to identify the ULO boundary for three socially and ecologically important anadromous fishes (Oncorhynchus spp.) in a subset of representative streams across a complex river network in southwestern Washington State, USA, and quantify the relationship of the ULO with landscape attributes for these species. Extensive field surveys covering 669 river km across two years documented the ULO in 115 terminal streams (i.e., uppermost independent stream segment within a stream network) for coho salmon (O. kisutch), 97 terminal streams for steelhead trout (O. mykiss), and 57 terminal streams for chum salmon (O. keta). The landscape attributes associated with these ULO locations varied among species. For example, precipitation was an important predictor only for coho salmon, whereas slope was an important predictor only for steelhead trout. In contrast, drainage area, elevation, and geology were important predictors for all species; while the direction was the same for drainage area and elevation, the magnitude of the effect of each landscape attribute varied among species. I demonstrated that large-scale landscape attributes can accurately and consistently detect species-specific distribution boundaries across broad and diverse habitat (percent correct classification:78%-89%; area under the receiver operating characteristic curve: 0.87-0.96). The ability to quantify landscape attributes related to distribution boundaries illuminates how the biology and life history of a species is captured across the landscape. The second goal of this work was to predict the range of occurrence as a function of landscape attributes for coho salmon, steelhead trout, and chum salmon across a range of probability decision thresholds, that reflect different risk-tolerance scenarios and determine whether stream reaches are within or outside the range of occurrence. Generalized linear mixed models were used to compare the quantity of currently described distribution used in restoration planning in the basin and quantify the amount of habitat inaccessible due to anthropogenic barriers. The change in amount of habitat within the predicted range of occurrence across probability decision thresholds ranged from 60%-74% among species. Differences between the model predictions and the currently described distribution for each species ranged from -14% to 171%, which on a whole indicates that the amount of habitat being considered for restoration is currently underestimated. As predicted, species with a greater range of occurrence (e.g., coho salmon) had a greater percentage of predicted suitable habitat inaccessible due to anthropogenic barriers (coho salmon:17.4%-28.8%, 0.75-0.25 PDT; steelhead trout:10.2%-17.5%; chum salmon: 3.9%-12.3%), and the locations of these barriers varied among species. Modelling species distributions at multiple levels of risk-tolerance allows practitioners to weigh the ecological benefits and financial investment when considering locations for restoration. Ultimately, the effective consideration of restoration actions requires tools such that managers can weigh the trade-offs of their decisions given that not all actions equitably benefit all species.
    • How aspen tree height influences aspen leaf miner (Phyllocnistis populiella) oviposition and performance

      Tundo, Giovanni; Doak, Pat; Wagner, Diane; Breed, Greg (2021-05)
      Under the optimal oviposition theory, insects are expected to lay eggs on hosts that maximize the success of their offspring. Tree height is known to be an important factor influencing the distribution of phytophagous insects because some species perform better at a distinct range of heights. This difference in performance could lead to incorrect estimates of population parameters if surveys are only conducted on one host plant height. Aspen leaf miners (Phyllocnistis populiella) have undergone a major outbreak in interior Alaska over the last two decades. We quantified patterns of aspen leaf miner oviposition and juvenile survival over 2 years and found that aspen leaf miners were approximately 1.5 times more likely to survive on tall trees than short trees. Parasitism and both egg and larval predation were lower on tall trees. Aspen leaf miners on tall trees also had larger pupal masses than those on short trees. Although aspen leaf miners performed better on tall trees, the number of eggs laid per leaf did not significantly differ by tree height. There were no significant differences in leaf foliar nitrogen between tall and short trees. We also found little differences in wind speed between tall and short trees that could explain ovipositional patterns. Ovipositional patterns may partially reflect the difference in phenology between tall and short aspen trees. Aspen leaf miners only lay eggs on new leaves. Tall aspen trees leafed out 7 days earlier on average than short aspen trees, and tall trees, unlike short trees, ceased to produce new leaves after budburst. Consequently, there was little overlap in the availability of tall and short aspen trees for oviposition, so even if aspen leaf miners have a preference for laying more eggs on tall than short trees, they can only act on it during the short time period when tall trees are available for oviposition. The results suggest that population projections based on data collected from only short trees may underestimate future aspen leaf miner population growth due to lower juvenile survival rates and pupal masses on short trees. More broadly, the results highlight the importance of examining multiple tree heights when studying the performance and population dynamics of phytophagous insects. They also suggest that phenological differences between plants may constrain insects from using higher quality hosts.
    • Reevaluating recent temporal trends in animal body size: the role of demography

      Theriot, Miranda K.; Olson, Link; Doak, Patricia; Millien, Virginie (2021-05)
      Climate change over recent decades is associated with varied responses in animals, including both increases and decreases in body size. These opposing trends are often attributed to two primary hypotheses. In warm-blooded vertebrates, Bergmann's rule predicts decreases in average size with increasing temperature, based on the relationship between body size and thermoregulation. Alternatively, increased average body size is linked with changes in resource availability as summer growing seasons lengthen and winters becomes milder. We propose a third explanation, that shifts in demography underlie some of these observed trends, as many species change in size or shape throughout life. The influence of thermoregulatory demands, resources, and demography on body size trends are not mutually exclusive; disentangling these effects and identifying overarching patterns requires detailed analyses across multiple locations and taxa, which in turn necessitates repeatable and expandable studies. To that end, here we propose three best practices in body size research: defining and justifying measures of size, citing museum specimens, and accounting for demography. We employed these guidelines in a study on masked shrews (Sorex cinereus) in Alaska. We found evidence of age-based differences in total body length, tail length, skull length, and skull width; however, correcting for age did not have a strong effect on the apparent trends in size over time. Based on linear mixed models, mean total length and tail length increased from 1951-1991, consistent with previous findings. Additionally, our results revealed slight increases in mean skull length and toothrow length over the 40-year study period. There was some indication of differing trends between age classes in both of these measurements. These results were not statistically significant, but our sample size of overwintered adults was relatively small, so further study is needed to fully investigate age-specific size trends in masked shrews. In summary, this thesis highlights the importance of repeatability in body-size research and emphasizes the importance of demography in the study of these trends.
    • Investigations on the impacts of ship traffic in the Bering Sea on aerosol optical depth using automatic identification systems data, and MODIS collection 6.1 data

      Summers, Tyler; Mölders, Nicole; Friberg, Mariel; Fochesatto, Javier (2021-05)
      Increasing Arctic shipping requires study of the increasing aerosol emissions impact on aerosol optical depth (AOD) in the Bering Sea and the Bering Strait. This study used Moderate Resolution Imaging Spectroradiometer (MODIS) 550 nm AOD 3 km products to study the seasonal variability over the length of the Arctic shipping season, from June to October, over 2011 and 2014. Bucket resampling was used to project and downscale the MODIS AOD to a 0:25 by 0:25 grid during overpasses. An overpass is dened as consecutive MODIS granules from both the Terra and Aqua satellites. Ship positional data obtained from automatic identication systems (AIS) was aggregated to hourly data. Collocation of ships and AOD from overpasses were determined for all quarter degree grid cells and times. Area-weighted means for both grid-cells with ship occurrence and without ships were determined for each month. AOD decreases with increasing time in the shipping season due to the increasing frequency of low pressure system and hence aerosol removal via washout and scavenging. Comparison of the AOD of 2011 and 2014 revealed that the position of the Aleutian Low not only strongly aects the sample size, but also AOD over the Bering Sea. The sea-ice area seemed to be without notable impact on the number of ships and AOD. A weak positive correlation was found between AOD and the number of ships present in the same grid cell during a overpass for 7 out of the 10 months. A strong skewing towards October occurred in 2011 due to a strong positive correlation of the number of data points.
    • Sled dogs as a model for studying dietary vitamin D

      Striker, Kali; Dunlap, Kriya; Jerome, Scott; Drew, Kelly (2021-05)
      Vitamin D deficiency (VDD) has become a pandemic and has shown to be correlated with several poor health outcomes. Many factors that lead to VDD are environmental and lifestyle. Vitamin D has physiological implications involved in all areas of human health and is also important for animal health. Canines have shown adverse health outcomes similar to humans that correlate with vitamin D deficiency such as chronic kidney disease (CKD) and irritable bowel disease (IBD). Canine vitamin D requirements are largely unknown due to the lack of research and the wide ranges of supplementation throughout dog food manufacturers. Pre-active plasma vitamin D metabolites are used as the biomarker of vitamin D status in humans and dogs but may not be representative of overall vitamin D status. Therefore, other biomarkers representing vitamin D status are often used in conjunction to determine physiological relevance. To address this gap in knowledge, this study used parathyroid hormone concentrations as well as vitamin D binding protein concentrations to establish more of an overall status of vitamin D. In canines, clinical supplementation following VDD is usually administered orally with vitamin D olive oil tablets; however, supplementation is usually unsuccessful. Vitamin D and its metabolites are lipid soluble and stored in adipose tissue. Although few foods provide appreciable levels of vitamin D, wild salmon contain some of the highest dietary vitamin D levels. People living in Alaska are at an increased risk of VDD due to reduced zenith sun angles for much of the year. Consequentially sufficient vitamin D levels need to be acquired through diet or supplementation. Historically, Alaska Natives obtained sufficient amounts of vitamin D from traditional subsistence foods, but with the progressive shift away from these foods VDD has increased in Alaskan populations. The limited research available suggests that Alaskan sled dogs in particular are a group found to be generally VDD. Sled dogs are an important part of the traditional Alaska subsistence lifestyle and have evolved alongside humans in the circumpolar north. Sled dogs, therefore, provide a valuable model for studying health outcomes associated with VDD in both people and dogs in the far north. This study provides significant evidence showing wild Alaskan salmon as a dietary source of supplementation to raise 25(OH)Vitamin D serum in dogs after only 4 weeks. We also show significance in variation by confounding factors, age and sex.
    • Computational and experimental evaluation of nanofluids in heating and cooling forced convection applications

      Strandberg, Roy; Das, Debendra K.; Peterson, Rorik A.; Johnson, Ronald A.; Goering, Douglas J. (2021-05)
      The purpose of the research was to examine the heat transfer and fluid dynamic performance of various nanofluids in heating and cooling applications using empirical and computational methods. Two experiments were performed to characterize and compare the performance of a Al₂O₃/60% ethylene glycol (60% EG) nanofluid to that of its base fluid. In the first experiment, the nanofluid was comprised of Al₂O₃ nanoparticles with 1% volumetric concentration in a 60% ethylene glycol/40% water (60% EG by mass) solution to that of 60%EG in a liquid to air heat exchanger. The test bed used in the experiment was built to simulate a small air handling system typical of that used in heating, ventilating and air conditioning (HVAC) applications. Previously established empirical correlations for thermophysical properties of fluids were used to determine the values of various parameters (e.g. Nusselt number, Reynolds number, and Prandtl number). The testing shows that the 1% Al₂O₃ nanofluid generates a marginally higher heat rate than the 60% EG under certain conditions. At Re=3,000, the nanofluid produced a heat rate that was 2% higher than that of the 60% EG. The empirically determined Nusselt number associated with the convection inside the coil tubing follows the behavior predicted by the Dittus-Boelter correlation quite well (R²=0.97), while the empirically determined Nusselt number for the 60% EG follows the Petukhov correlation similarly well (R²=0.97). Pressure loss and hydraulic power for the nanofluid were higher than for the base fluid over the range of conditions tested. The exergy destroyed in the heat exchange and fluid flow processes were between 8 and 13% higher for the nanofluid over the tested range of Reynolds numbers. The objective of the second study was to experimentally characterize and compare the performance of a nanofluid comprised of Al₂O₃ nanoparticles with 1, 2 and 3% volumetric concentrations in a 60% EG solution to that of 60% EG in a liquid to air heat exchanger. In this experiment, the heating system was operated in a higher temperature regime than in the first experiment. As in the first experiment, the test bed used in the experiment simulated a small air handling system typical of that used in HVAC applications. Entering conditions for the air and liquid were selected to emulate typical operating conditions of commercial air handling systems in sub arctic regions (such as Alaska). In the experiment the nanofluids generally did not perform as well as expected based on previous analytical work. The performance of the 1% nanofluid was generally equal to that of the base fluid considering identical entering conditions. However, the 2% and 3% nanofluids performance was considerably worse than that of the base fluid. The higher concentration nanofluids exhibited heat rates up to 14.6% lower than that of the 60%EG, and up to 44.3% lower heat transfer coefficient. The 1% Al₂O₃/60% EG exhibited 100% higher pressure drop across the coil than the base fluid considering equal heat output. In the computational portion of the research, the performance of a microchannel heat sink (MCHS), similar to those used to cool microprocessors filled with various nanofluids and the corresponding base fluid without nanoparticles are examined. The MCHS is modeled using a three- dimensional conjugate heat transfer and fluid dynamic finite-volume model over a range of conditions. The model incorporates a fixed heat flux of 1,000,000 W/m² at the base of the solid domain. The thermophysical properties of the fluids are based on empirically obtained correlations, and vary with temperature. Nanofluids considered include 60% Ethylene Glycol/40% Water solutions with CuO, SiO₂, and Al₂O₃ nanoparticles dispersed in volumetric concentrations ranging from 1 to 3%. The flow conditions analyzed are in the laminar range (50£Re£300), and consider multiple inlet temperatures. The analyses predict that when compared on an equal Reynolds number basis, the 60%EG/3% CuO nanofluid exhibits the highest heat transfer coefficient, and the largest reduction in average base temperature. At an inlet Reynolds number of 300, and an inlet temperature of 308K the nanofluid is predicted to have an average heat transfer coefficient that is 30% higher than that of the base fluid, while the average temperature on the base of the heat exchanger is 1K lower than that of the base fluid. In contrast, the inlet pressure required for these entering conditions is 192% higher than that for the base fluid, while the required hydraulic power to drive the flow is 366% higher than that of the base fluid. The enhanced heat transfer performance potential of nanofluids comes at the expense of generally higher pumping power consumption.
    • Advancing wildfire fuel mapping and burn severity assessment in Alaskan boreal forest using multi-sensor remote sensing

      Smith, Christopher William; Panda, Santosh; Bhatt, Uma; Meyer, Franz (2021-05)
      Wildfires in Alaska have been increasing in frequency, size, and intensity putting a strain on communities across the state, especially remote communities lacking firefighting infrastructure to address large scale fire events. Advances in remote sensing techniques and data provide an opportunity to generate high quality map products that can better inform fire managers to allocate resources to areas of most risk and inform scientists how to predict and understand fire behavior. The overarching goal of this thesis is therefore to build insight into methods that can be applied to create highly detailed fire statistic map products in Alaska. To address this overarching goal we tested several methods for generating fire fuel, burn severity, and wildfire hazard maps that were validated using data collected in the field. Applying the Random Forest classifier on Airborne Visible/ Infrared Imaging Spectrometer Next-Generation (AVIRIS-NG) hyperspectral data we were able to produce a fire fuel map with an 81% accuracy. We then tested two supervised machine learning classifiers, post fire standard spectral indices, and differenced spectral indices for their performance in assessing burn severity. We found that supervised machine learning classifiers outperform other algorithms when there is an adequate amount of training data. Using the support vector machine and random forest classifiers we were able to generate burn severity maps with 83% accuracy at the 2019 Shovel Creek Fire. Lastly, we looked for a relationship between burn severity and environmental conditions prevalent during the Shovel Creek and Nugget Creek fires. Overall, these products can be used by fire managers and scientists to assess fire risk, limit the damages caused by wildfires through adequate resource allocation, and provide the guidelines for creating future high quality fire fuel maps.
    • Development of working fluid control techniques for improved ramping response in geothermal-based organic Rankine cycle generation systems

      Shofowora, Abayomi John; Wies, Richard; Denkenberger, David; Al-Badri, Maher (2021-05)
      Small-scale low-temperature geothermal-based electricity generation systems are under development for use as grid supporting and grid forming power sources in remote locations. Conversion of low-temperature heat to electrical energy in an organic Rankine cycle using working fluids such as refrigerants is challenging due to the low energy conversion efficiency of the process and the significantly slower thermal response rate in comparison to the time response of the electrical grid for changes in electrical generation and load. There is a need to investigate techniques for controlling the flow of the working fluid in combination with the use of a secondary heat exchanger to improve ramping response of these systems. This research project develops and models a working fluid control technique that incorporates power electronic technologies that could help to improve the ramping response of geothermal-based organic Rankine cycle generation systems. The performance of the model is examined with the aid of simulations in MATLAB® Simulink®. The results from these simulations are used to develop a functional and reliable control technique for ramping response improvement in geothermal-based electricity generation systems using organic Rankine cycles.
    • Contextualizing the development of coastal adaptations in postglacial Southeast Alaska

      Schmuck, Nicholas S.; Reuther, Joshua; Clark, Jamie; Baichtal, James F.; Holliday, Vance T.; Plattet, Patrick (2021-05)
      The goal of this dissertation is to improve our understanding of human population expansions into unfamiliar environments, focusing on when and how humans adapted to the rich coastal landscape of Southeast Alaska. Investigation of the peopling of this region has been overshadowed by the broader narrative that the Americas may have been first colonized by a late Pleistocene coastal migration. Refinements to local sea-level and paleoecological chronologies help contextualize the dynamic landscape that these first inhabitants might have encountered, returning focus to the archaeology of Southeast Alaska itself. This research considers existing archaeological data within the theoretical framework of Human Behavioral Ecology, proposing new models to acknowledge the process of landscape learning. Landscape learning provides a mechanism for exploring human adaptation to unfamiliar landscapes, which in turn produces testable hypotheses based on the familiarity of colonizing human foragers with coastal environments. Systematic sourcing of obsidian microblade cores, ubiquitous in early Holocene sites, allows for a further assessment of landscape learning, alongside an evaluation of the relationship between local raw material constraints and technological organization. Though the oldest known archaeological sites in Southeast Alaska are firmly dated to between 10,500 and 10,000 cal BP, older occupations have been identified elsewhere on the Northwest Coast, and Tlingit and Haida oral histories record their presence on the landscape from Time Immemorial. Taken together, multiple lines of evidence point to an initial colonization of Southeast Alaska out of eastern Beringia, occurring prior to the occupation of the oldest known sites. By the early Holocene, foragers with a typical Northwest Coast diet were readily adapting to, but still in the process of learning, this complex coastal landscape. While these results challenge the long-established impression that the oldest known sites in the region represent a remnant population of maritime sea-mammal hunters descended from an earlier coastal migration into the Americas, this research highlights the opportunity to continue testing these hypotheses by targeting older, uplifted paleoshorelines.
    • An evaluation of GPR techniques for analyzing the safety of Interior Alaskan ice roads under varying river ice and environmental conditions

      Richards, Elizabeth M.; Stuefer, Svetlana; Maio, Chris; Belz, Nathan; Daanen, Ronald (2021-05)
      Ice roads and bridges are necessary routes to transport heavy equipment, supplies and food in the winter months to and from isolated cold region communities off the road system. Ice roads allow for community members to avoid the high costs of air shipments and obtain equipment and vehicles that would otherwise not be available. These ice roads traverse frozen bodies of water (e.g., rivers, estuaries, and lakes), and require extreme safety when driving over. To achieve this, calculations are frequently completed to determine the maximum acceptable loading on the ice cover. River ice tends to have increased safety concerns and uncertainty for travel that stem from warmer air temperatures and other factors such as precipitation, snow drifting, and ice cover forming differently each year. The necessity of obtaining time intensive ice thickness measurements by hand puts the responsible personnel at considerable risk of injury or fatality. Ground penetrating radar (GPR), which has gained much popularity in the last few decades, is a quicker and more effective non-invasive method for measuring ice thickness and other properties. The GPR system was tested for its accuracy in measuring ice thickness on common transportation routes on the Yukon River and the Tanana River. Identification of varying ice type layers in river ice cover using GPR was also attempted. While layers could not be identified using the 450 MHz and 750 MHz central frequency antennas, an accuracy analysis of GPR ice thickness measurements under various environmental conditions was completed. This analysis contributes to a comprehensive understanding of the safety of ice roads for community members in remote northern villages and provides the basis for further research on identifying layers in river ice cover.
    • Computational analysis of nanofluids flow and heat transfer in microchannels and fin tube air coils

      Ray, Dustin R.; Das, Debendra K.; Peterson, Rorik A.; Misra, Debasmita; Kim, Sunwoo (2021-05)
      The four goals of this dissertation were to investigate nanofluids' thermal and fluid dynamic performance in (i) an air coil, (ii) microchannel heatsink, using computational fluid dynamic (CFD) software, ANSYS Fluent, develop (iii) hydrodynamic entrance length correlation and (iv) apparent friction factor correlations in rectangular microchannels. In cold regions of the world, ethylene glycol mixed with water (EG/W) are used as a heat transfer fluid instead of water due to their freeze protection. EG/W has low thermal conductivity than water, which can be improved by dispersing nanoparticles and creating a new fluid called nanofluid. A computational scheme was developed based on the Effectiveness-Number of Transfer Unit (ε-NTU) method to compare nanofluids' thermal and fluid dynamic performance to the conventional ethylene glycol and water mixture. The nanofluid's performance was examined by conducting two studies: reducing pumping power and reducing the air coil's surface area via length. The results showed at a dilute concentration of 1% of Al₂O₃ can reduce the pumping power requirements by 35.3% or reduce the air coil length by 7.4% while maintaining the same heat transfer rate as EG/W. The results show nanofluids could provide significant savings in energy or material costs. The nanofluids' (Al₂O₃, CuO, and SiO₂) thermal and fluid dynamic performance used in a microchannel heatsink was explored using analytical and computational methods. The computational model was developed in ANSYS Fluent. Comparing analytical and computational results, good agreement was observed validating both methods. The three nanofluids had a maximum difference of 4.1% for pressure drop and 2.9% for the Nusselt number. Three performance studies were conducted using the analytical model based on constant Reynolds number, maximum surface temperature, and pumping power. A constant Reynolds number of nanofluids could reduce the maximum surface temperature by 6K, but at the cost of increased pumping power. Nanofluids showed the pumping power could be reduced by 23% compared to the base fluid while maintaining equal maximum surface temperature. In electronic cooling applications where microchannel heatsinks are used, nanofluids seem promising for lowering critical components' operating temperatures and contribute to increased life and system reliability. A detailed three-dimensional laminar flow CFD model was developed and ran for Reynolds numbers ranging from 0.1 to 1000 through six rectangular microchannels aspect ratios (α): 1, 0.75, 0.5, 0.25, 0.2, 0.125. The majority of the Reynolds numbers simulated were in the low regime (Re< 100) to fulfill the lack of literature for determining accurate hydrodynamic entrance length and apparent friction factor for microchannels. From these numerical simulations, improved correlations were developed to predict hydrodynamic entrance length with a mean error of less than 2% and a maximum error of 5.75% for 0.1 ≤ Re ≤ 1000 & 0 ≤ α ≤ ∞. For the apparent friction factor in microchannels, three correlations were derived from the numerical simulations: fully developed friction factor (fRe), developing incremental pressure drop number (K(z)), and fully developed incremental pressure drop (K(∞)). The three correlations were used to determine the local fapp,zRe, in the applicable range of 0.1 ≤ Re ≤ 1000 & 0.125 ≤ α ≤ 8. The correlations showed a mean deviation of less than 3% and a maximum deviation of less than 8.3% from the numerical data.
    • Photosensitized degradation of chlorothalonil and chlorpyrifos in the presence of Arctic derived dissolved organic matter

      Quesada, Ginna; Guerard, Jennifer; Rasley, Brian; Green, Thomas (2021-05)
      Pesticides used at mid latitudes can accumulate in Arctic environments. Two commonly detected pesticides in Arctic lakes are chlorothalonil and chlorpyrifos. In surface waters, photolysis can play an important role in the attenuation of contaminants. The chemical characteristics of dissolved organic matter (DOM) can further alter the extent of photolytic degradation of pollutants. To determine the relative effect of natural Arctic lake water and its DOM on the photolysis of chlorpyrifos, experiments were conducted under natural Arctic irradiation and under artificial irradiation. Similarly, the effect of Arctic DOM was investigated for chlorothalonil under artificial irradiation. The fulvic acid (FA) fraction of DOM was isolated from Fog 1 and from Toolik Lake in May and July. Lake waters significantly enhanced the photodegradation of chlorpyrifos under natural light by up to an order of magnitude. FA's significantly increased the degradation of chlorpyrifos (>2x) and chlorothalonil (>100x) under artificial irradiation relative to 18 MΩ-cm Water. Toolik Lake FA isolated in May, significantly enhanced the photolysis of both contaminants relative to the isolate collected in July. In the presence of iron, a lower ratio of carbohydrates and peptides to aromatics in the FA's was associated with faster degradation for chlorothalonil.
    • Influence of environmental attributes on intertidal community structure in glacial estuaries

      McCabe, Mary K.; Konar, Brenda; Iken, Katrin; Kelley, Amanda (2021-05)
      High-latitude coastal environments are experiencing dramatic changes due to climate warming. Increased glacier discharge rates modulate downstream environmental conditions in coastal watersheds. These fast-changing environments are predicted to influence the structure of nearshore marine communities. Here, rocky intertidal community structure, recruitment of key organisms, and environmental correlates were examined at nine watersheds in two regions (Kachemak Bay and Lynn Canal) that bookend the Gulf of Alaska, which were separated by approximately 1000km. Each watershed was part of a gradient in each of the regions that spanned 0-60% glacial coverage. Percent cover, biomass surveys, and recruitment of intertidal organisms, along with environmental monitoring of salinity, temperature, dissolved oxygen, river discharge, turbidity, and nutrient loading were completed from April - September 2019 in each watershed. Biological community structure and variance were analyzed by taxa and by ecological group (i.e., primary producer, filter feeder, omnivore, grazer, predator) and then in relation to the local environmental spatiotemporal profiles. In general, larger watersheds with more glacial coverage and river discharge resulted in higher cover of primary producers and less cover of filter feeders. This pattern was more apparent in the region with more oceanic influence as compared to the other region located within an inlet. In relation to specific environmental drivers, salinity was negatively correlated with primary producer cover (r = -0.52), but positively associated with barnacle cover (r = 0.40). Additionally, turbidity was positively correlated with primary producer biomass (r = 0.50), but negatively correlated with mussel cover (r = -0.30). In contrast, there was a positive relationship among mussel recruitment and discharge and turbidity. There was variability in within-ecological group response between regions that could be a response to local circulation and oceanic influences. Barnacles were the main filter feeder species driving patterns in the more saline region located close to the open ocean, while mussels drove patterns in the other less oceanic region. As glaciers recede, environmental conditions, such as salinity, will increase and turbidity will decrease, which may alter future intertidal community assemblages dominated by filter feeders.
    • Trend analysis of temperature, precipitation, and stream flow in the National Petroleum Reserve Alaska

      Marshall, Sara; Toniolo, Horacio; Rasley, Brian; Schnabel, William (2021-05)
      Seven hydro-meteorological stations in the National Petroleum Reserve Alaska were analyzed to look at precipitation, discharge, and temperature trends. These hydro-meteorological stations included: Fish Creek, Judy Creek, Ikpikpuk, Ublutuoch, Seabee, Prince, and Otuk. A linear regression was performed on a year-by-year basis to fill in data gaps in the temperature time series, for all six stations with temperature data. The Seasonal Mann-Kendall test and a Modified Seasonal Mann-Kendall test were performed to determine if a trend appeared present in the time series and, if so, how significant the trend was. The Sen's slope analysis was then utilized to determine the magnitude of the trend, if a trend was observed in both analyses. The temperature trends showed an increasing trend in the temperature data for four stations: Judy Creek, Ublutuoch, Fish Creek, and Ikpikpuk. No trend was shown in the remaining station, Otuk station. One station, Prince, was removed from analysis due to a high percentage of missing data. The Modified Seasonal Mann-Kendall tests showed a trend in four of the five stations, and a slight positive trend in one of the five stations. The precipitation data showed 'no trend' in the Seasonal Mann-Kendall analysis. The Modified Seasonal Mann-Kendall test showed a slight trend (Fish Creek), a moderate trend (Otuk), and no trend (Ikpikpuk) for the precipitation data. Using the seasonal Mann-Kendall analysis the discharge data showed no trend in five out of seven stations and two trends (Fish Creek and Seabee). The Modified Seasonal-Mann-Kendall analysis showed and a significant trend twice (Fish Creek and Seabee), a moderate trend three times (Ikpikpuk, Prince, Otuk), a slight trend once (Ublutuoch), and no trend one time (Judy Creek) in the discharge data.
    • The sound of 1001 indigenous drums: the catalytic cycle of Fire Eagle, Golden Eagle, Thunderbird

      Marsden, Davita Aphrodite-Lee; Topkok, Sean Asiqłuq; Smith, Graham Hingangaroa; John, Theresa; Leddy, Shannon (2021-05)
      I have witnessed Indigenous students experience marginalization, being ignored, being labelled, and earning developmental designations, all as a way to continue systemically oppressing them. Indigenous students traditionally did not sit in rows, they did not compete for the highest mark, an A+ or a B. Indigenous education and learning is a process, and no one fails. Systemic oppression continues in public education where Indigenous students are alienated, being pushed out, kicked out, or continuously transferred from school to school. After fasting for 1,000 days, I received a vision of how to move Indigenous education forward: I began making Indigenous drums; I taught singing to students, staff, and admin. Reinstatement of Indigenous culture such as drumming and singing increases self-esteem, self-identity, confidence, and self-determination for the learner and is a tool for healing intergenerational trauma. These cultural supports, therefore, become critical for the success of Indigenous students and they are helping Indigenous education and people move forward without fear. There is a hegemonic imbalance of power and we need a reallocation of government funds in public education. Indigenous students have the right to attend school and participate without penalty, punishment, or humiliation. Swept under the school "welcome mat" are all forms of racism in public education. Critical Indigenous theory considers unequal power relations as they affect urban Indigenous students. The imbalance creates marginalization and prejudices towards Indigenous students. This dissertation uses retrospective study on the students' Artwork Stories, a free expression that allows specific elements and past patterns to emerge and reveal that Indigenous drumming and singing correlates to specific values and emotions. The spirit of Indigenous iv drumming and singing gives the student a visual voice in research through the Artwork Story documents. The Gichi'ayaag (Elders) say the Medicine Wheel has many teachings, as many as there are grains of sand in this world. The Complex Medicine Wheel Model shapeshifts into the Medicine Wheel Colour Knowledge Chart analytical model, providing a research tool that analyzes students' Artwork Stories experience. The sound of the Indigenous drum will ripple around the world and continue its transformation one beat at a time. Our unceded territories are calling back languages and the spirits of the land to further Indigenous education. This drum's voice bridges those of the Ancestors, the women, and our spirits. When you hear the sound of an Indigenous drum in your school, you will know we bring change, a change that you cannot stop, nor would you want to. The analysis of Indigenous drumming and singing aligns with evidence-based approaches and the quantification of learning. There is an urgent need to Indigenize K-12 curriculum by incorporating Indigenous drumming and singing into their classrooms. Those who promote Indigenous pedagogy and culture have just begun to Indigenize the education of Indigenous peoples into mainstream public education. Now is the time when Indigenous education and culture are on the rise and can be recognized as paramount for Indigenous student success. This research will benefit all learners in public education.
    • Anfechtung

      Lyew, Daniel Emerson; Johnson, Sara; Reilly, Terry; Carr, Richard; Farmer, Daryl (2021-05)
      This thesis is a collection of poetry that explores the relationships between time, memory, identity, freedom, and meaning within the context of a shifting and unsteady world. The collection is organized along a trajectory not unlike that of Dante's Divine Comedy, moving through inner and outer landscapes of uncertainty and anxiety before emerging in more ambiguous, subtle spaces. Allusion is used to suggest the continuity and fragmentariness of a tradition (similar to T. S. Eliot's "The Waste Land"), reformation and response to a tradition (as in Nets by Jen Bevin), and the chancy contingencies of personal experience. Formally, the poems use a wide variety of strategies and forms including erasure and non-traditional lineation to suggest various states of being ranging from the hypnagogic and nightmarish to the nostalgic and wistful, and ultimately to something like hope. The poems also range from highly confessional modes to more abstract, imagistic modes to similarly suggest motion and change.