Theses for the College of Natural Sciences & Mathematics

Recent Submissions

  • Growth of juvenile chinook salmon (Oncorhynchus tshawytscha) as an indicator of density-dependence in the Chena River

    Perry, Megan T. (2012-08)
    In management of Pacific salmon, it is often assumed that density-dependent factors, mediated by the physical environment during freshwater residency, regulate population size prior to smolting and outmigration. However, in years following low escapement, temperature may be setting the upper limit on growth of juvenile chinook salmon Oncorhynchus tshawytscha during the summer rearing period. Given the importance of juvenile salmon survival for the eventual adult population size, we require a greater understanding of how density-dependent and independent factors affect juvenile demography through time. In this study we tested the hypotheses that (1) juvenile chinook salmon in the Chena River are food limited, and (2) that freshwater growth of juvenile chinook salmon is positively related with marine survival. We tested the first hypotheses using an in-situ supplemental feeding experiment, and the second hypothesis by conducting a retrospective analysis on juvenile growth estimated using a bioenergetics model related to return per spawner estimates from a stock-recruit analysis. We did not find evidence of food limitation, nor evidence that marine survival is correlated with freshwater growth. However, we did find some evidence suggesting that growth during the freshwater rearing period may be limited by food availability following years when adult escapement is high.
  • Foods and foraging ecology of oldsquaws (Clangula hyemalis L.) on the arctic coastal plain of Alaska

    Taylor, Eric John (1986-09)
    The study was conducted from June to September during 1979 and 1980 in the the West Long Lake area of the National Petroleum Reserve-Alaska. Additional oldsquaws were collected in the inland wetlands near the northwest boundary of the reserve at Ice Cape. West Long Lake and the adjacent Goose Lake are located 15 miles south of the Beaufort Sea and immediately west of Teshekpuk Lake.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Effects of target properties on the formation of lunar impact craters in the simple-to-complex transition

    Chandnani, Mitali; Herrick, Robert; Kramer, Georgiana; Larsen, Jessica; Dehn, Jonathan (2019-12)
    The transition from simple to complex crater morphology in impact craters with increase in crater size has been modelled and observed in planetary bodies across the Solar System. The transition diameter depends upon the strength and gravity of the planetary body. On the Moon, this transition takes place over a diameter range of several kilometers. This range spans a diversity of crater morphologies including simple, transitional and complex craters. The diameter range of 15 20 km falls within the lunar simple-to-complex transition. All other impactor properties held constant, the 15-20 km range corresponds to a factor of three in the magnitude of impact kinetic energy. I conducted detailed geologic investigation of 244 well-preserved craters in this diameter range to elucidate the root causes of morphological variations. I used panchromatic data for observing crater and surface morphology, Digital Elevation Models (DEMs) for evaluating crater morphometry and topographic variation of pre-impact terrain, near-infrared (NIR) bands for determining the composition of crater cavity and surrounding terrain, thermal infrared bands for examining rock abundance, and Synthetic Aperture Radar (SAR) data for detecting impact melt deposits. The results of my investigation indicate that the morphological differences are primarily governed by target properties. Simple craters are confined to the highlands, and the mare are more abundant in complex craters. The mare are composed of solidified basaltic lava flows interlayered with regolith. The layering creates vertical strength heterogeneities that drive the destabilization of the transient cavity and its collapse, causing the transition to complex craters at smaller diameters in the mare. The non-layered highlands are more vertically homogeneous in strength and therefore favor simple crater formation. Eight atypically deep simple craters were identified in the highlands near the mare highlands boundaries, the most porous terrains on the lunar surface. After detailed examination of these craters in comparison to their normal-depth counterparts, I conclude that part of the energy from impact on porous target was spent in target compaction. The higher the porosity of the target, the deeper the crater and greater its volume, due to increased compaction. That only some of the craters in the high porosity terrains are deep suggests that those craters are on locally extreme-high porosity patches. However, an unusual impactor property, such as a high velocity impact, a high density impactor, or a near-vertical impact may also be a contributor. The simple craters in the highlands were observed to be located on flat or gradually sloping surfaces or degraded rims and terraces of pre-existing craters. Most craters with localized slumps superpose sharp topographic breaks such as well-developed rims and terraces of pre-existing craters. However, the topographic settings of 35% of the craters with localized slumps appeared to be similar to that of the simple craters. More detailed topographic study of the pre-impact terrains of these two morphologies revealed that the pre-impact terrains of 35% of the craters with localized slumps are gradually sloping or have subtle topographic breaks. Both sharp and subtle breaks are characterized with similar sloping directions as the adjacent craters' walls, which led to over steepening of the transient cavity walls around this part of the rim and their collapse, thereby causing the accumulation of localized slumped material. Several simple craters were also identified to have formed on pre-impact topographic breaks. However, the simple craters' walls that superpose these breaks were observed to be sloping in directions opposite to that of the breaks. So the ejecta around these walls was deposited along the break slopes, and thus syn-impact mass wasting occurred external (and not internal) to the crater cavity.
  • Foliage and winter woody browse quality of an important Salix browse species: effects of presence of alder-derived nitrogen and winter browsing by Alaskan moose (Alces alces gigas)

    Burrows, Justin; Kielland, Knut; Wagner, Diane; Ruess, Roger (2019-12)
    In this study, I examined the relationship between soil nitrogen and winter browsing by moose on the physical and chemical characteristics of Salix alaxensis; specifically stem production, leaf nutritional quality, and stem nutritional quality of tissues produced the following growing season. I measured stem biomass production the 2013 growing season and offtake during the 2013-2014 winter browsing season at 16 sites on the Tanana River floodplain near Fairbanks, Alaska. I revisited the sites the following summer and autumn to assess regrowth and to collect soil, foliage, and stem samples. Browsing intensity and total soil nitrogen were similar in sites with and without alder, a nitrogen-fixing shrub. Soil nitrogen and browsing intensity were not consistently related to changes in stem or leaf quality, although there were significant relationships in some subsets. Soil nitrogen and browsing intensity also did not have consistent relationships with stem regrowth the following growing season. These results indicate that S. alaxensis growing in this system are able to recover from a naturally broad range of browsing utilization, including very high levels of offtake, and continue to produce nutritious leaves and stems.
  • Response of major modes of eastern Arctic Ocean variability to climate change

    Baumann, Till M.; Polyakov, Igor V.; Bhatt, Uma S.; Walsh, John E.; Weingartner, Thomas J. (2019-12)
    The Arctic Ocean plays a central role in ongoing climate change, with sea ice loss being the most prominent indicator. Recent observations showed that Atlantic inflows play an increasingly important role in the demise of sea ice. This encroaching atlantification of the eastern Arctic Ocean impacts the mean state and the variability of hydrography and current dynamics throughout the basin. Among the most energetic modes of variability are the seasonal cycle and high frequency semidiurnal (∼12-hourly) dynamics in the tidal and inertial frequency band. Limited observations indicated a substantial increase of both, hydrographic seasonal cycles as well as semidiurnal current dynamics in the eastern Arctic over the last decade. Using a uniquely comprehensive data set from an array of six moorings deployed across the eastern Eurasian Basin (EB) continental slope along the 125°E meridian between 2013 and 2015 within the NABOS project, we assess the state of hydrographic seasonal cycles in the eastern EB. Results show a complex pattern of seasonality with a remarkably strong (∆T=1.4°C), deep reaching (∼600 m) temperature signal over the continental slope and large-scale seasonal displacements of isopycnal interfaces. Seasonally changing background conditions are also the main source of variability of semidiurnal frequency band currents: During winter, vigorous baroclinic tidal currents whose amplitudes by far exceed predictions follow the vertical evolution of the pycnocline. During summer, extensive open-water periods additionally lead to strong wind-driven inertial currents in the upper ocean, routinely exceeding 30 cm/s far offshore in the deep basin. In order to obtain an Arctic-wide perspective on the impact of baroclinic tidal currents, a pan-Arctic tidal current atlas has been developed that synthesizes all available observations from the last 20 years. This atlas allows for in-depth studies of regional baroclinic tidal current variability as well as for validation of ocean and climate models, an essential step towards more accurate projections of the future Arctic Ocean state. Our findings from the eastern EB region already indicate a new, more dynamic state of the eastern Arctic Ocean with direct implications for the ecosystem and further sea-ice reduction.
  • Planning for positive outcomes: testing methods for measuring outdoor recreation preferences on public lands

    Wright, Roger Bryant; Fix, Peter J.; Little, Joseph M.; Dodge, Kathryn (2019-08)
    Outcomes-Focused Management is based on the idea of four levels of demand for recreation: demand for recreation activities, recreation settings, recreation experiences, and lasting benefits of recreation. Public lands can provide the setting, and thus the opportunity for people to engage in meaningful outdoor recreation activities to realize desired experiences and lasting benefits. Implementation of this management framework requires identifying desired outcomes and understanding how management of public lands recreation settings affects visitors' ability to realize them. This thesis addresses the two tasks. The Fairbanks Community Recreation Study investigated current methods of identifying demands for different types of recreation trips, revealing two key shortcomings. First, demand studies often rely solely on activity participation data and thus fail to account for latent demand and desires for meaningful experiences and benefits. Second, data from demand studies are either too general to be useful in site management, or too specific to one site to account for the range of needs within a community. An online survey was developed to characterize salient and latent demands for outdoor recreation in the context of the greater Fairbanks, Alaska community. A unique survey format allowed respondents to describe their hypothetical "ideal" outdoor recreation trips, the required setting characteristics, and what actual places in the region might realistically provide such a trip. Trip profiles yielded a typology of desired recreation for the region. By connecting these types of trips to real places, local land managers can identify which demands they are uniquely equipped to provide for and how to better cater to latent demands. To address the task of measuring the effectiveness of outcomes-focused management practices, an exploratory factor analysis was conducted on data from 13 recreation benefits surveys collected at recreation areas in three western states. Factor structures among individual studies converged on two primary domains of Personal Benefits of recreation and Community Benefits from recreation, each containing a number of potential subdimensions. By identifying latent factors of the recreation benefits construct the study brings research closer to developing and validating a survey instrument to measure lasting beneficial recreation outcomes to individuals and their communities.
  • Demographics and telomere dynamics of hibernating Arctic ground squirrels (Urocitellus parryii)

    Wilbur, Sara M.; Williams, Cory; Barnes, Brian; Kitaysky, Alexander; Podlutsky, Andrej (2019-08)
    Aging is the complex process by which an organism loses functional integrity over time. Several measurable contributors to or components of the aging process have been identified, one of which is telomere length. Telomeres are the repetitive, nucleoprotein structures located at the ends of linear chromosomes. In general, telomeres shorten over time and when exposed to damaging reactive oxygen species (highly unstable molecules released as a byproduct of cellular respiration). Organisms that have unique physiologies, in addition to those that live longer than otherwise predicted, have recently inspired comparative telomere dynamics studies. Hibernating mammals, which exhibit both heterothermy and long lifespan, have served as models for these new investigations into telomere length dynamics. Several studies over the past decade have measured the effects of torpor (the period of hibernation characterized by extremely low metabolic rates and body temperature) and arousal (from torpor; a brief return to euthermic or high levels of body temperature) on telomere length change in hibernators. This body of work demonstrated that telomere length is preserved across hibernation seasons (likely due to the majority of hibernation spent in torpor), and any telomere shortening that does occur is correlated with arousal frequency. However, all telomere-hibernator studies to date have focused on hibernators from temperate regions and on DNA from a peripheral tissue (either buccal cells or skin tissue). Arctic ground squirrels, the northernmost hibernator and ground squirrel species, are appropriate model candidates to expand the diversity of research in hibernator telomere dynamics, as they remain thermogenic during torpor to defend a viable body temperature against subfreezing ambient temperatures. Maintaining high metabolic rates to support thermogenesis throughout torpor--and over arousals--may lead to increased telomere attrition in this species compared to other hibernators adapted to milder climates. This thesis begins with basic arctic ground squirrel demographics from two well-studied populations in Arctic Alaska. I report that (female) arctic ground squirrels appear to be similarly long-lived as other hibernating species, and that sex-specific differences in lifespan may be driven by behavioral differences between males and females. I also present results from a study comparable to those performed in temperate hibernators: I measured telomere length in freeliving arctic ground squirrels across hibernation and age groups and found that, as in temperate hibernators, telomere length (in ear tissue) is maintained across hibernation. Expanding upon single-tissue telomere studies, I also measured telomere length in brown adipose tissue (the tissue responsible for non-shivering thermogenesis for heat generation during torpor and at arousal initiation), liver, and heart in captive arctic ground squirrels and found that telomeres shortened dramatically in brown adipose tissue only. Overall, this work identifies arctic ground squirrels as capable of maintaining cellular integrity (as measured via telomere length) and of reaching surprising longevity in the face of extreme environmental conditions.
  • Constraining the H₂O/CO₂ molar ratio, the volume fraction of exsolved volatiles, and the magma compressibility of the 2006 Augustine eruption, Alaska

    Wasser, Valerie; Lopez, Taryn; Izbekov, Pavel; Larsen, Jessica; Anderson, Kyle; Freymueller, Jeffrey (2019-08)
    Geodetic modeling of volcano deformation can be used to estimate the volume of magma presumed to be mobilized within a volcanic system. These geodetically modeled subsurface reservoir volume changes are commonly much smaller than simultaneous eruptive volumes, where the eruptive volume is estimated based on geological mapping of units, their thicknesses, and their densities. This discrepancy is thought to be at least partially due to magma compressibility, which describes the phenomena where the volume of a given mass of magma changes as pressure increases/decreases primarily due to the presence of highly compressible exsolved volatiles. In this study, I combine deformation, volcanic gas, and petrologic constraints acquired prior to and during the 2006 eruption of Augustine volcano, Alaska, to estimate the amount of exsolved volatiles present in the magma storage region prior to the eruption and calculate the resulting compressibility of the magma. By doing so, I am able to constrain the H₂O/CO₂ molar ratio of the syn-eruptive gas emissions to between 24 and 59, with my best estimate of 28. My results suggest that for the specific parameters of Augustine's magmatic system, including a pressure of 120-170 MPa, a temperature of 880 ± 13 °C, and 40 ± 2% phenocrysts by volume, an exsolved volatile phase of about 8.2 vol% and a magma compressibility of ~7.1 x 10⁻¹⁰ 1/Pa are required to explain the observed eruptive volume to deformation volume ratio equal to three. The exsolved volatile volume and magma compressibility values determined here agree with results of previous studies of volatile-rich volcanic systems. This study reiterates that magma compressibility is an important factor that must be considered when interpreting deformation data within volatile-saturated volcanic systems.
  • Application of new technology for the diagnosis of viral infection

    Parker, Jayme; Chen, Jack; Hueffer, Karsten; Ferrante, Andrea; Jilly, Bernd (2019-08)
    New technology is challenging conventional methods for characterizing pathogenic viruses in clinical laboratories. These newer methods are superior to older methods due to their ability to broadly target numerous pathogens in multiplexed ways. Even more intriguing, new technologies are capable of detecting viruses in non-targeted manners. Before these newer methods can be adopted by accredited medical laboratories, they must be validated to assess whether or not they meet minimum federal standards in terms of assay accuracy, precision, reproducibility, and cross-reactivity. This thesis begins to answer important questions facing clinical laboratories when adopting new technology. In Chapter 1, assays targeting single virus types are compared to a multiplexed assay using a proprietary electrochemical detection technology to determine if multiplexing has a detrimental effect on analytical sensitivity when detecting respiratory viruses simultaneously. Chapter 2 focuses on the issue of false positivity when testing for viruses in low-prevalence populations. To evaluate this, a multiplex flow immunoassay technology is used to perform surveillance of human immunodeficiency virus (HIV) infection in Alaskans, a low HIV-prevalence population. Chapter 3 describes clinical diagnostic applications of next-generation sequencing (NGS) providing examples of how NGS compares to conventional methods for characterizing pathogenic viruses such as hepatitis C virus, herpesvirus, adenovirus, and influenza virus. The final chapter describes how NGS can be used to characterize viruses by geographical region of transmission by analyzing an outbreak of canine parvovirus that occurred in the interior of Alaska. This chapter serves as a clear example of NGS's appeal to enhancing our epidemiological understanding during outbreaks. Although there are significant challenges to implementation, especially for NGS, each chapter shows promise in new technologies for clinical laboratories.
  • Multi-sensor techniques for the measurement of post eruptive volcanic deformation and depositional features

    McAlpin, David B.; Meyer, Franz J.; Begét, James; Webley, Peter W.; Dehn, Jonathan (2019-08)
    Remote sensing of volcanic activity is an increasingly important tool for scientific investigation, hazard mitigation, and geophysical analysis. These studies were conducted to determine how combining remote sensing data in a multi-sensor analysis can improve our understanding of volcanic activity, depositional behavior, and the evolutionary history of past eruptive episodes. In a series of three studies, (1) optical photogrammetry and synthetic aperture radar are combined to determine volumes of lahars and lava dome growth at Redoubt Volcano, Alaska; (2) applied data from multiple synthetic aperture radar platforms are combined to model long-term deposition of pyroclastic flow deposits, including past deposits underlying current, observable pyroclastic flow deposits at Augustine Volcano, Alaska; and finally (3) combined, low-spatial-resolution thermal data from Advanced Very High Resolution Radiometer sensors are combined with high resolution digital elevation models derived from the microwave TanDEM-X mission, to increase the accuracy of eruption profiles and effusion rates at Tolbachik Volcano on the Kamchatka Peninsula, Russian Far East. As a result of this study, the very diverse capabilities of multiple remote sensing instruments were combined to improve the understanding of volcanic processes at three separate locations with recent eruptive activity, and to develop new methods of measurement and estimation by merging the capabilities of optical, thermal, and microwave observations. With the multi-sensor frameworks developed in this study now in place, future efforts should focus on increasing the diversity of sensor types in joint analyses, with the objective of obtaining better solutions to geophysical questions.
  • Lidar and radar studies of turbulence, instabilities, and waves in the Arctic middle atmosphere

    Li, Jintai; Collins, Richard L.; Newman, David E.; Simpson, William R.; Thorsen, Denise L.; Williams, Bifford P. (2019-08)
    This dissertation presents new studies of gravity waves and turbulence in the Arctic middle atmosphere. The studies employ lidars and radar to characterize wave activity, instability and turbulence. In the lidar-based studies, we analyze turbulence and wave activity in the MLT based on lidar measurements of atmospheric temperature, density and sodium density, temperature and wind. This combination of measurements provides simultaneous characterization of both the atmospheric stability as well as material transport that allow us to estimate the eddy diffusion coefficient associated with turbulence. We extend the scope of previous studies by developing retrievals of potential temperature and sodium mixing ratio from the Rayleigh density temperature lidar and sodium resonance density lidar measurements. We find that the estimated values of turbulent eddy diffusion coefficients, K, of 400-2800 m²/s, are larger than typically reported (1-1000 m²/s) while the values of the energy dissipation rates, ε, of 5-20 mW/kg, are more typical (0.1-1000 mW/kg). We find that upwardly propagating gravity waves accompany the instabilities. In the presence of instabilities, we find that the gravity waves are dissipating as they propagate upward. We estimate the energy available for turbulence generation from the wave activities and estimate the possible turbulent energy dissipation rate, εGW. We find that the values of εGW are comparable to the values of ε. We find that the estimate of the depth of the layer of turbulence are critical to the estimate of the values of both ε and εGW. We find that our method tends to overestimate the depth, and thus overestimate the value of ε, and underestimate the value of εGW. In the radar-based study, we conduct a retrieval of turbulent parameters in the mesosphere based on a hypothesis test. We distinguish between the presence and absence of turbulence based on fitting Voigt-based and Lorentzian-based line shapes to the radar spectra. We also allow for the presence and absence of meteoric smoke particles (MSPs) in the radar spectra. We find examples of Poker Flat Incoherent Scatter Radar (PFISR) spectra showing both the presence and absence of turbulence and the presence and absence of MSPs in the upper mesosphere. Based on the analysis, we find that relatively few of the radar measurements yield significant measurements of turbulence. The significant estimates of turbulence have a strength that is over a factor of two larger than the average of the estimates from all of the radar measurements. The probability of true positives increases with the quality factor of the spectrum. The method yields significant measurements of turbulence with probabilities of true positives of greater than 30% and false positives less than 0.01%.

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