Theses for the College of Natural Sciences & Mathematics

Recent Submissions

  • 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%.
  • Plant succession in the Arctic Brooks Range: floristic patterns from alpine to foothills, along a glacial chronosequence and elevation gradient

    Kasanke, Shawnee A.; Walker, Donald A.; Chapin, F. Stuart III; Mann, Daniel H. (2019-08)
    In the wake of rapid glacial retreat, alpine habitats in the Arctic are expanding as freshly exposed surfaces become vegetated. Many glaciers in alpine cirques have nearly disappeared, and little is known about the rate of colonization or pioneer communities that develop following deglaciation. Newly developed habitats may provide refugia for sensitive Arctic flora and fauna, especially in light of polar warming. To assess this process, vegetation communities developing on two recently deglaciated moraines in the Central Brooks Range were surveyed and compared with communities along a transect spanning both a glacial chronosequence (40-125,000 years since deglaciation) and an elevation gradient (1700-500 m) into the Arctic foothills. Results show that primary succession begins almost immediately following deglaciation. Within forty years fine-grained and rock substrates hosted small communities of 8-13 vascular and nonvascular plant species. Many pioneer taxa, especially lichens, persist into later stages of succession. Overall succession is directional and slow, increasing in species richness for about 10,000 years, after which richness decreases and communities stabilize. This is the first vegetation study on primary succession in the high Central Brooks Range, providing a missing link to a vegetation transect along the Arctic Bioclimatic gradient.
  • Mechanisms regulating the circannual rhythm of hibernation

    Frare, Carla; Drew, Kelly L.; Bult-Ito, Abel; Green, Thomas K.; Kuhn, Thomas B. (2019-08)
    Hibernation is a unique adaptation to conserve energy entering a hypometabolic (low metabolic rate) and hypothermic (low body temperature) state called torpor. Torpor is characterized by a drop in metabolism to 1-2% of basal metabolic rate and a decrease in body temperature to one to two degrees above ambient temperature. Metabolic rate is restored to basal metabolic rate and body temperature increases from 2-3⁰C to 36⁰C during the regularly timed arousal. The adenosine A1 receptor agonists promote the onset of hibernation and torpor in different species, through a yet undefined neuronal circuit. In the Arctic ground squirrel, CHA, an adenosine A1 receptor agonist, induces hibernation during the winter- hibernation season but not in summer even when the environmental conditions are kept constant (ambient temperature of 2⁰C and a light cycle of 4L:20D). Thus, the phenomenon of CHA-induced hibernation is entrained to an endogenous circannual rhythm. In this work, I aim to identify the changes in neuronal activation that reflect the circannual rhythm regulating the seasonal difference in response to CHA. Arctic ground squirrels, housed at constant ambient temperature (2°C) and light cycle (4L:20D), were implanted with body temperature transmitters. I collected tissue during Summer, Fall, Winter and Torpor conditions for seasonal analysis. For treatment analysis, I collected tissue form animals treated with CHA or vehicle in Summer and Winter. Primarily, I used immunohistochemistry to identify cell groups affected by season and treatment. I used cFos to identify neuronal activity and other immunohistochemical markers to identify neuronal phenotypes, based on specific cytoplasmic proteins. An overall seasonal decrease in thermogenesis, measured as reduced neuronal activity in the thermoregulatory pathways, and increase in vasoconstriction reflected the higher order processing necessary for CHA-induced hibernation. CHA inhibited the histaminergic neurons in the hypothalamus suppressing wakefulness and dis-inhibited the nucleus tractus solitarius, further suppressing thermogenesis. Preliminary data also suggested a seasonal change in the adenosine metabolic pathway, which may have increased adenosine receptor sensitivity during the hibernation season. Our results suggest that histaminergic neurons in the hypothalamus and the nucleus tractus solitarius are likely targets to manipulate metabolic demand in the clinical setting inducing therapeutic hypothermia or increasing metabolic rate.
  • Feeding ecology of scaup ducklings across a heterogeneous boreal wetland landscape

    DuBour, Adam J.; Lindberg, Mark; Gurney, Kirsty; Hundertmark, Kris (2019-08)
    Understanding how patterns of food resources influence the behavior and fitness of free-living animals is critical in predicting how changes to such resources might influence populations. The boreal region of North America is relatively undeveloped and contains abundant freshwater lakes and wetlands. These largely pristine and stable habitats harbor high densities of aquatic invertebrates, which are a critical food source for the numerous waterbird species that breed in the boreal. Invertebrates are of particular importance for the optimal growth and survival of waterbird chicks. However, observations of long-term change to boreal aquatic habitats and their invertebrate populations associated with a warming climate has been implicated in the declines of some boreal breeding waterbirds, such as the lesser scaup (Aythya affinis). Lesser scaup are known to feed extensively on amphipods, a freshwater crustacean; however, ducklings have been shown to have a diverse diet. Our goal was to use the naturally occurring heterogeneity of aquatic invertebrates across boreal lakes within the Yukon Flats National Wildlife Refuge in interior Alaska to better understand how changes in invertebrate prey resources might affect diet selection and growth in lesser scaup ducklings. First, we used a stable isotope approach to quantify the variation in the trophic niche within our population of ducklings. We found that as a population, lesser scaup ducklings consume a variety of aquatic insects, crustaceans and mollusks, and that variation in the population diet is largely attributable to variation in diet between birds from different lakes with different invertebrate communities. Second, we used the same habitat heterogeneity to examine how gradients of invertebrate abundance relate to the growth of ducklings. We observed that lesser scaup ducklings experienced reduced growth rates in lakes that had little to no amphipods. Taken together, these results suggest that while lesser scaup ducklings are a flexible consumer that can adapt to changes in invertebrate populations, ducklings may face negative fitness repercussions when consuming prey other than amphipods.
  • Learning from the local scale: identifying and addressing local blind spots in Arctic environmental governance

    Curry, Tracie; Meek, Chanda; Trainor, Sarah; Berman, Matthew; Lopez, Ellen; Streever, Bill (2019-08)
    Environmental governance in the context of climate change adaptation brings together diverse actors and stakeholders to develop and enact policies across a broad range of scales. However, local needs and priorities are often mismatched with those pursued by entities at different levels of decision-making. This mismatch is perpetuated, in part, by the dominating influence of the Western worldview in knowledge processes involving the creation, sharing, and use of environmental knowledge. Persistent biases that favor Western science and technical information while marginalizing other important sources like local and Indigenous knowledge create blind spots that may adversely affect adaptation outcomes. In this research, a case study of the Native Village of Wainwright, Alaska is used to explore the topic of information blind spots in environmental governance resulting from 1) low resolution tools employed within broad scale adaptation initiatives; 2) preferences for easily quantifiable information; and 3) the challenge of communicating context-rich details to outside decision makers, given disciplinary biases and organizational conventions. This dissertation comprises manuscripts based on three studies undertaken to address the above blind spots in specific areas of adaptation planning. The first manuscript furthers conventional methods of adaptation classification through a place-based approach that uses directed content analysis to identify aspects of local adaptation not readily captured by low resolution frameworks. The second manuscript employs contextual analysis and extends Ostrom's Institutional Analysis and Development framework to characterize the role of local informal institutions in adaptation and provide insights into how difficult-to-quantify social and cultural norms might be leveraged in planned adaptation initiatives. The third manuscript reports on a formative endeavor that looked practically at conventions for communicating environmental change to public sector decision-makers, and tested a survey that explored the potential for context-rich visuals and other reporting strategies to effectively convey information about local observations and experiences of change.
  • Solar magnetic fields: source, evolution, and interaction with planetary magnetospheres

    Burkholder, Brandon; Delamere, Peter; Otto, Antonius; Newman, David; Ng, Chung-Sang; Connor, Hyunju (2019-08)
    Magnetized plasmas with twisted and filamented magnetic fields are pervasive throughout the heliosphere. In the solar magnetic field, photospheric convection on scale sizes from granules to differential rotation is responsible for driven magnetic reconnection. These reconnection sites are closely related to the magnetic topology, which is highly complex as the magnetic field is structured by a network of many thousands of magnetic flux concentrations. The coronal plasma overlying this "magnetic carpet" is the source of the solar wind flow, which has been found to be turbulent as close to the sun as our observations can currently resolve. At 1 AU, observations have also revealed a highly structured solar wind which we posit in this thesis originates in the corona rather than forming in-transit. Further, the solar wind-magnetosphere interaction depends on variability in the solar wind. When the boundary between solar wind plasma and magnetospheric plasma is unstable to the growth of Kelvin-Helmholtz waves, driven magnetic reconnection can occur on the magnetopause boundary. Such reconnection allows magnetic field to thread the boundary and transport can take place. We quantify the solar wind interaction for a corotation dominated system in terms of the mass and momentum transport driven by Kelvin-Helmholtz instabilities. Model-data comparisons are performed in this thesis using both the magnetohydrodynamic and hybrid-kinetic approaches for fluid simulations.
  • Risk analysis of Cordova's microgrid from a complex systems viewpoint

    Bowker, Anna Lipetzky; Newman, David; Huang, Daisy; Wackerbauer, Renate (2019-08)
    Cordova is a town of approximately 2,000 people located on the southern coast of Alaska. A power grid for a town this size, with a large seasonal fishing economy, is considered a moderate to large sized microgrid in terms of power produced. Understanding the vulnerabilities and risks of failures in such a grid is important for planning and operations and investigating these characteristics in the context of complex system dynamics is novel. The analysis of Cordova's microgrid is a case study relevant to a large class of microgrid communities that could benefit from this work. Our analysis of this grid began by looking at the distribution of all outages from 2003 - 2017 by size, followed by splitting up outages based on certain characteristics and again looking at outage size distribution based on different characteristics. Following this we correlated the outages with different weather patterns and then with the hourly load demand on the system. After doing these analyses we developed a risk metric to give a single numerical value to the risk of an outage occurring during certain time periods and under certain conditions. We looked at risk in the summer versus the winter due to the summer having a much larger load demand, and we also looked at the risk before and after all cables in the grid were buried underground. This gives us an idea of when/under what circumstances the most outages are likely to occur and allows us to run our model of the system, make changes, and determine if those changes were beneficial to the system or not.
  • Paleobiology of ichthyosaurs: using osteohistology to test hypotheses of growth rates and metabolism in a clade of secondarily aquatic marine tetrapods

    Anderson, Katherine L.; Druckenmiller, Patrick; Erickson, Gregory; Horstmann, Lara; Fowell, Sarah (2019-08)
    Ichthyosaurians (Ichthyosauria) are one of the most prominent groups of secondarily aquatic Mesozoic marine reptiles. Over their 160 million years of evolution, the clade evolved a streamlined body plan with paddle-like limbs, convergent with modern cetaceans. Despite the fact that ichthyosaurians have been studied by paleontologists for over a century, very little is known about aspects of their biology, including quantification of their age structure and growth rates. Multiple lines of evidence, including oxygen isotope, swimming modality, and body shape analyses suggest that ichthyosaurians experienced elevated growth rates and likely maintained an elevated body temperature relative to ambient sea water. In this dissertation, I test these hypotheses using osteohistological methods. In the first manuscript, we describe new material of the small-bodied Upper Triassic ichthyosaurian Toretocnemus from the Nehenta Formation and the Hound Island Volcanics (both Norian, Upper Triassic) of Southeast Alaska. During the Upper Triassic, ichthyosaurians experienced their greatest size disparity, with large-bodied species rivaling the size of modern blue whales (Balaenoptera musculus; 20+ m body length) living alongside small-bodied species (1 m body length) like Toretocnemus. Prior to this study, Toretocnemus was known from Carnian deposits of California and possibly Sonora, Mexico. The referred material described here expands its geographic and temporal range. There are very few known ichthyosaurians from the Norian; thus, this material sheds light on the clade's diversity before the end Triassic extinction event. In the second and third manuscripts, we use osteohistological methods to describe the microstructure of various skeletal elements of two species of Stenopterygius from the Posidonia Shale (Lower Jurassic) of Germany. The Posidonia Shale is a Konservat-Lagerstätten that preserves over 3000 ichthyosaurian specimens, approximately 80 percent of which are referable to Stenopterygius. First, we sampled over 40 skeletal elements from one individual specimen referred to Stenopterygius quadriscissus to 1) describe the mineralized tissues across the skeleton, 2) infer relative growth rate, and 3) identify elements with growth marks. Almost all elements described demonstrate fibrolamellar primary bone, indicative of a rapid growth rate. We also identify growth marks in several elements, including the dentary and premaxilla, that will be used in future growth studies. In the third manuscript, we sample a scleral ossicle from Stenopterygius triscissus to describe its microstructure and investigate the use of ossicles for skeletochronology. The use of scleral ossicles for determining age structure has been documented in extant sea turtles as well as dinosaurs. We sectioned one ossicle in three planes and document conspicuous growth banding in the short axis section. Although this method requires further testing, we tentatively determine a minimum age of 7 years at the time of death for this individual. This dissertation lays critical groundwork for future studies of the paleobiology of ichthyosaurians. We are already in the preliminary stages of using these results to 1) quantify age structure and growth rates of an ichthyosaurian (Stenopterygius quadriscissus) for the first time, and 2) test the use of scleral ossicles for skeletochronology of ichthyosaurians. Through addressing these basic aspects of ichthyosaurian biology, we can begin to investigate how ichthyosaurian development and physiology changed over time and space and develop a greater understanding of this clade's 160 million years of evolution.
  • The effect of rate, frequency, and form of migration on host parasite population dynamics

    Mottet, Geneva; Drown, Devin M.; Newman, David; Wackerbauer, Renate (2019-08)
    What is the effect of migration on host-parasite population dynamics? Animals live in a landscape where they move between patches. They are also locked in host-parasite conflicts. Host-parasite interactions are modeled with consumer resource functions. I constructed models using two different consumer resource functions (the Lotka Volterra system and the Saturating Type II system). The first model was a conservative system. The second was dissipative and more biologically realistic. I examined the effect of rate of migration, time between migration events, and form of migration. I found that the time between migration events had the largest effect on the synchronization in host-parasites population dynamics between the patches. Decreased time between migration events increased the fraction of simulation to completely synchronize and decreased the time it took to do so. In the first model, I observed simulations with a low rate of migration took a long time to synchronization and with a high rate of migration took a short time to synchronize. There was a phase transition between these two amounts of time it took to synchronize. In the second model, simulations done at low rates of migration did not synchronize while with increased migration rates the fraction of simulations to synchronize increased. I found in some simulations of parasite only migration that the patches synchronized faster. My results imply that parasite only migration to islands could have a greater impact on the extinction risk on islands further from the mainland than other forms of migration.
  • Black bear denning ecology and habitat selection in interior Alaska

    Smith, Martin E.; Follmann, Erich; Dean, Fred; Hechtel, John; Bowyer, Terry (1994-12)
    To identify conflicts between existing black bear (Ursus americanus) management and human activity on Tanana River Flats, Alaska, we monitored 27 radio-collared black bears from 1988-1991. We compared denning chronology, den characteristics, den-site selection, and habitat selection across sex, age, and female reproductive classes. Mean den entry was 1 October and emergence was 21 April, with females denned earlier and emerging later than males. Marshland and heath meadow habitats were avoided, and willow-alder was selected for den-sites. Eighty-three percent of dens were excavated, 100% contained nests, 18% were previously used, and 29% had flooded. Black bears selected black spruce-tamarack and birch-aspen significantly more, and marshland and heath meadow significantly less than available. Marshland and birch-aspen were used significantly more in spring than autumn. Marshland was used less than available by all bears in all seasons. Special habitat or den-site requirements are not critical for management of Tanana River Flats black bears.
  • Role of antioxidant supplementation and exercise regimen in handling oxidative stress from natural PM2.5 exposure due to boreal forest fire

    Witkop, Jacob J.; Dunlap, Kriya; Duffy, Lawrence; Reynolds, Arleigh (2019-05)
    Particulate matter 2.5 (PM2.5) exposure induces oxidative stress that causes many negative health outcomes such as cancer, cardiovascular disease and neurodegenerative disease. Research shows that dietary antioxidants and an up-regulated endogenous antioxidant response from exercise play key roles in the antioxidant defense against oxidative stress. This study is the first to use an animal model to investigate the cumulative effects of using lifestyle interventions of antioxidant supplementation (Arthrospira platensis) and exercise regimen on the antioxidant response before, during, and after ambient PM2.5 exposure. In a two-factorial, longitudinal design, sled dogs (n=48) were divided into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of exercise and antioxidant regimen on antioxidant response after one month of implemented exercise and supplementation protocol and (2) measure the antioxidant response of all groups during and after a natural forest fire event in 2015. Commercial assays for Total antioxidant Power (TAP) and the enzymatic antioxidant Superoxide Dismutase (SOD) were used as markers for the total antioxidant response and the endogenous response at all time points. During the forest fire, SOD was increased 5-10-fold over pre/post-exposure levels in all groups suggesting potential implication for using SOD as a marker for the acute response to environmental stress. TAP was increased in the exercise groups after one month of exercise protocol implementation, demonstrating the cytoprotective increase of antioxidants after repeated exercise.
  • An exploration of two infinite families of snarks

    Ver Hoef, Lander; Berman, Leah; Williams, Gordon; Faudree, Jill (2019-05)
    In this paper, we generalize a single example of a snark that admits a drawing with even rotational symmetry into two infinite families using a voltage graph construction techniques derived from cyclic Pseudo-Loupekine snarks. We expose an enforced chirality in coloring the underlying 5-pole that generated the known example, and use this fact to show that the infinite families are in fact snarks. We explore the construction of these families in terms of the blowup construction. We show that a graph in either family with rotational symmetry of order m has automorphism group of order m2m⁺¹. The oddness of graphs in both families is determined exactly, and shown to increase linearly with the order of rotational symmetry.
  • Data analysis and data assimilation of Arctic Ocean observations

    Stroh, Jacob Nathaniel; Panteleev, Gleb; Mölders, Nicole; Weingartner, Thomas; Rhodes, John (2019-05)
    Arctic-region observations are sparse and represent only a small portion of the physical state of nature. It is therefore essential to maximize the information content of observations and bservation-conditioned analyses whenever possible, including the quantification of their accuracy. The four largely disparate works presented here emphasize observation analysis and assimilation in the context of the Arctic Ocean (AO). These studies focus on the relationship between observational data/products, numerical models based on physical processes, and the use of such data to constrain and inform those products/models to di_erent ends. The first part comprises Chapters 1 and 2 which revolve around oceanographic observations collected during the International Polar Year (IPY) program of 2007-2009. Chapter 1 validates pan- Arctic satellite-based sea surface temperature and salinity products against these data to establish important estimates of product reliability in terms of bias and bias-adjusted standard errors. It establishes practical regional reliability for these products which are often used in modeling and climatological applications, and provides some guidance for improving them. Chapter 2 constructs a gridded full-depth snapshot of the AO during the IPY to visually outline recent, previouslydocumented AO watermass distribution changes by comparing it to a historical climatology of the latter 20th century derived from private Russian data. It provides an expository review of literature documenting major AO climate changes and augments them with additional changes in freshwater distribution and sea surface height in the Chukchi and Bering Seas. The last two chapters present work focused on the application of data assimilation (DA) methodologies, and constitute the second part of this thesis focused on the synthesis of numerical modeling and observational data. Chapter 3 presents a novel approach to sea ice model trajectory optimization whereby spatially-variable sea ice rheology parameter distributions provide the additional model flexibility needed to assimilate observable components of the sea ice state. The study employs a toy 1D model to demonstrate the practical benefits of the approach and serves as a proof-of-concept to justify the considerable effort needed to extend the approach to 2D. Chapter 4 combines an ice-free model of the Chukchi Sea with a modified ensemble filter to develop a DA system which would be suitable for operational forecasting and monitoring the region in support of oil spill mitigation. The method improves the assimilation of non-Gaussian asynchronous surface current observations beyond the traditional approach.
  • Modelling investigation of interaction between Arctic sea ice and storms: insights from case studies and climatological hindcast simulations

    Semenov, Alexander; Zhang, Xiangdong; Bhatt, Uma; Hutchings, Jennifer; Mölders, Nicole (2019-05)
    The goal of this study is to improve understanding of atmosphere, sea ice, and ocean interactions in the context of Arctic storm activities. The reduction of Arctic sea ice extent, increase in ocean water temperatures, and changes of atmospheric circulation have been manifested in the Arctic Ocean along with the large surface air temperature increase during recent decades. All of these changes may change the way in which atmosphere, sea ice, and ocean interact, which may in turn feedback to Arctic surface air warming. To achieve the goal, we employed an integrative approach including analysis of modeling simulation results and conducting specifically designed model sensitivity experiments. The novelty of this study is linking synoptic scale storms to large-scale changes in sea ice and atmospheric circulation. The models were used in this study range from the regional fully coupled Arctic climate model HIRHAM-NAOSIM to the ocean-sea ice component model of the Community Earth System Model CESM and the Weather Research and Forecasting (WRF) model. Analysis of HIRHAM-NAOSIM simulation outputs shows regionally dependent variability of storm count with a higher number of storms over the Atlantic side than over the Pacific side. High-resolution simulations also reproduce higher number of storms than lower resolution reanalysis dataset. This is because the high-resolution model may capture more shallow and small size storms. As an integrated consequence, the composite analysis shows that more numerous intense storms produce low-pressure systems centered over the Barents-Kara-Laptev seas and the Chukchi-East Siberian seas, leading to anomalous cyclonic circulation over the Atlantic Arctic Ocean and Pacific Arctic Ocean. Correspondingly, anomalous sea ice transport occurs, enhancing sea ice outflow out of the Barents-Kara-Laptev sea ice and weakening sea ice inflow into the Chukchi-Beaufort seas from the thick ice area north of the Canadian Archipelago. This change in sea ice transport causes a decrease in sea ice concentration and thickness in these two areas. However, energy budget analysis exhibits a decrease in downward net sea ice heat fluxes, reducing sea ice melt, when more numerous intense storms occur. This decrease could be attributed to increased cloudiness and destabilized atmospheric boundary layer associated with intense storms, which can result in a decrease in downward shortwave radiation and an increase in upward turbulent heat fluxes. The sea ice-ocean component CICE-POP of Community Earth System Model (CESM) was used to conduct sensitivity experiment to examine impacts of two selected storms on sea ice. CICE-POP is generally able to simulate the observed spatial distribution of the Arctic sea-ice concentration, thickness, and motion, and interannual variability of the Arctic sea ice area for the period 1979 to 2011. However, some biases still exit, including overestimated sea-ice drift speeds, particularly in the Transpolar Drift Stream, and overestimated sea-ice concentration in the Atlantic Arctic but slightly underestimated sea ice concentration in the Pacific Arctic. Analysis of CICE-POP sensitivity experiments suggests that dynamic forcing associated with the storms plays more important driving role in causing sea ice changes than thermodynamics does in the case of storm in March 2011, while both thermodynamic and dynamic forcings have comparable impacts on sea ice decrease in the case of the August 2012. In case of March 2011 storm, increased surface winds caused the reduction of sea ice area in the Barents and Kara Seas by forcing sea ice to move eastward. Sea ice reduction was primarily driven by mechanical processes rather than ice melting. On the contrary, the case study of August 2012 storm, that occurred during the Arctic summer, exemplified the case of equal contribution of mechanical sea ice redistribution of sea ice in the Chukchi - East Siberian - Beaufort seas and melt in sea ice reduction. To understand the impacts of the changed Arctic environment on storm dynamics, we carried out WRF model simulations for a selected Arctic storm that occurred in March 2011. Model output highlight the importance of both increased surface turbulent heat fluxes due to sea ice retreat and self-enhanced warm and moist air advection from the North Atlantic into the Arctic. These external forcing factor and internal dynamic process sustain and even strengthen atmospheric baroclinicity, supporting the storm to develop and intensify. Additional sensitivity experiments further suggest that latent heat release resulting from condensation/precipitation within the storm enhances baroclinicity aloft and, in turn, causes a re-intensification of the storm from its decaying phase.
  • Coming together at the table: partnering with urban Alaska Native families for their children's school success

    Roth, Karen L.; Vinlove, Amy; Topkok, Sean Asiqluq; Williams, Maria Shaa Tlaa; Jester, Timothy (2019-05)
    There is abundant research regarding the positive effects of family engagement as a factor in P-12 student success. Partnerships between home and school provide opportunities for students' families and educators to establish common goals and share meaning about the purpose of schooling. Unfortunately, mainstream outreach practices by Western educators have often failed to nurture authentic relationships with Indigenous families. This may be a contributing factor in lower academic success for too many Indigenous students. Historical educational practices in the U.S. for Indigenous students such as mandated attendance at distant boarding schools and English-only policies have adversely affected their languages and cultures worldwide and left a legacy of negative associations around schooling for many Native peoples. Non-Native educators continue to add to this disconnect with teaching pedagogies and curricula that are not responsive to Indigenous lifeways and values. In addition to inappropriate instructional methods and content, outreach strategies of non-Native educators may add to practices that marginalize Indigenous students and their families and discourage collaboration between home and school. This mixed-methods study sought to find family outreach strategies implemented by early childhood educators in the Anchorage School District (ASD) that build and nurture more culturally sustaining and relational approaches to building partnerships with Alaska Native families. Such practices are more likely to lead to student success for Native students. Research methods used were (a) a content analysis of ASD school-home communication fliers, (b) a survey of ASD preschool teachers on their outreach beliefs and practices with Native families, and (c) interviews with families of Alaska Native students.

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