Now showing items 1883-1902 of 3320

• #### Multiple stable isotopic analyses ([delta]¹³C, [delta]¹⁵N, [delta]¹⁸O, and [delta]D) of the Boulder Patch, a high arctic kelp community: trophic and temporal perspectives

The Boulder Patch, a high Arctic kelp community, is a rarity in the Alaskan Beaufort Sea. Considered a biodiversity oasis, this area provides habitat for many organisms. Trophic relationships, spatial patterns, and isotopic changes over time were examined within the Boulder Patch using stable carbon and nitrogen isotopes. 394 samples, representing over 55 species were analyzed. Isotope values showed considerable variability in the food web base, particularly for the kelp Laminaria solidungula. Isotopic values for most animals fit their known feeding strategies. Little spatial variation was observed in isotope values, however temporal differences were found in L. solidungula isotope values between 2002 and 2004, and between archived samples collected during the 1980's. To better understand patterns in stable oxygen and hydrogen isotopes, values were assessed and applied in an ecological context. Sixty-four samples were analyzed, encompassing 29 species. Results indicated distinct differences between primary producers and animals, offering insights into a possible application of [delta]¹⁸O and [delta]D in ecological studies. By defining trophic structure and elucidating feeding strategies of organisms, this study enhanced the biological knowledge in the Boulder Patch, providing ecological information on a high arctic kelp community.
• #### Multiresolution digital soil mapping of permafrost soils using a random forest classifier: an investigation along the Dalton Highway corridor, Alaska

In order to complete soil inventories in the remote permafrost zones of Alaska, there is a need to develop efficient digital soil mapping tools that can be applied over large areas using a minimum of ground truth data. This investigation first used a random forest classifier to test combinations of environmental input data at multiple resolutions (10m, 30m, and 100m). Five tiers of soil taxonomic units were predicted: Order, Suborder, Great Group, "Series Concept", and Particle Size Class. Model outputs are compared quantitatively via estimated out-of-bag accuracy, and qualitatively via visual inspection by soil scientists. Estimated out-of-bag accuracy ranged from ~45% to ~75%, with results improving when fewer classes were modeled. Model runs at 10m and 30m resolution performed comparably, with 100m resolution performing ~5-10% worse in most cases. Increasing the number of trees used, including categorical environmental input data (e.g. landforms), and replacement of environmental covariates with principal component analysis (PCA) bands did not significantly improve model performance. The random forest classifier was then used in a digital soil mapping pilot study along the Dalton Highway in northern Alaska. Parameters suggested in the initial study were used to predict multiple soil taxonomic classes from a basic collection of environmental covariates generated using high resolution (10m) satellite images and sparsely sampled pedon data. Covariates included maximum curvature, multiresolution valley bottom flatness, normalized height, potential incoming solar radiation, slope, terrain ruggedness index, and modified soil and vegetation index. Five tiers of soil taxonomic units were predicted: Order, Suborder, Great Group, "Series Concept", and Particle Size Class. Model outputs are compared quantitatively via estimated out-of-bag accuracy. Estimated out-of-bag accuracy ranged from ~45% to ~75%, with results improving when fewer classes were modeled. We suggest future research into optimized sampling to ensure an adequate distribution of samples across the feature space, and the incorporation of expert knowledge into accuracy assessments. Overall, digital soil mapping with random forest classifiers appears to be a promising method for completing the soil survey of Alaska.
• #### Multispecies Age-Structured Assessment Modeling As A Tool Of Fisheries Management In The Gulf Of Alaska

A multispecies age-structured assessment model (MSASA) for the Gulf of Alaska (GOA) is developed to examine the effects of integrating predation mortality into stock assessment efforts. Age-specific predation mortality is modeled as a flexible function of predator and prey abundances, constructed from species-preference and size-preference parameters and fitted to stomach-content data. Modeled species include arrowtooth flounder ( Atheresthes stomias), Pacific cod (Gadus macrocephalus), walleye pollock (Theragra chalcogramma), Pacific halibut (Hippoglossus stenolepis) and Steller sea lion ( Eumatopias jubatus). Recruitment, residual natural mortality, full-recruitment fishing mortality, and fishery/survey selectivities are estimated for pollock, cod, and flounder; abundances for apex predators sea lions and halibut are input. Estimated trophic structures and predation links show significant changes as a result of the inclusion of higher trophic level predators, and model results are highly sensitive to assumptions regarding sea lion diet. Simulation exercises suggest that model performance degrades more due to model misspecification and data scarcity than assumptions regarding data weighting and variance. Estimates of predation mortality work in tandem with survey data, constraining predation estimates in the face of incomplete diet data and potentially improving estimates of cohort structure. Exploration of predator functional responses (PFR) shows the default GOA MSASA Holling Type II PFR to be more flexible than initially thought, and that explicitly modeling predator competition for the same prey can improve model fit to stomach-content data. Median parameter estimates and their respective variances from the fitted MSASA model are used to construct management strategy simulations. Reducing fishing pressure on pollock during periods of high predator biomass is less effective at preserving pollock stocks than raising fishing pressure on flounder, and multispecies harvest control rules and biological reference points are shown to be more conservative and more efficient at preserving stock abundance while maintaining catch levels than their single-species counterparts.
• #### Multistate Ornstein-Uhlenbeck space use model reveals sex-specific partitioning of the energy landscape in a soaring bird

Understanding animals’ home range dynamics is a frequent motivating question in movement ecology. Descriptive techniques are often applied, but these methods lack predictive ability and cannot capture effects of dynamic environmental patterns, such as weather and features of the energy landscape. Here, we develop a practical approach for statistical inference into the behavioral mechanisms underlying how habitat and the energy landscape shape animal home ranges. We validated this approach by conducting a simulation study, and applied it to a sample of 12 golden eagles Aquila chrysaetos tracked with satellite telemetry. We demonstrate that readily available software can be used to fit a multistate Ornstein-Uhlenbeck space use model to make hierarchical inference of habitat selection parameters and home range dynamics. Additionally, the underlying mathematical properties of the model allow straightforward computation of predicted space use distributions, permitting estimation of home range size and visualization of space use patterns under varying conditions. The application to golden eagles revealed effects of habitat variables that align with eagle biology. Further, we found that males and females partition their home ranges dynamically based on uplift. Specifically, changes in wind and the angle of the sun seemed to be drivers of differential space use between sexes, in particular during late breeding season when both are foraging across large parts of their home range to support nestling growth.

• #### Music: a portrait of woman

Music in today's society is ubiquitous. It is in the car, the cinema, on television, in the doctor's office, in the home, on the other end of the phone; it really is everywhere. Music arguably is a large part of culture and as such, has the ability to construct social realities. In hopes to understand how media constructs the image of the female, a contextual analysis was performed on the lyrics of the top twenty-five country and pop songs according to Billboard.com. This was done using Grounded Theory through the employment of coding. Results showed that although country and pop music depict women in a slightly different manner, they both for the most part depict women in traditional gender roles. Furthermore, the propitiation and adherence to traditional gender roles sustain and conciliate patriarchy. Therefore the depictions of women in the music lyrics were then analyzed as processes of patriarchy.
• #### Mute Llama

The novella Mute Llama and the short story "The Keeper of Dogs" "both deal with the role that the imagination plays in the articulation of reality through symbols. At its core, this is an issue which involves the very essence of the creation of fictive worlds. In both pieces, the protagonist is engaged in a second-person, internal soliloquy as he is confronted with the startling fluidity of the "real" world of objects. When the objective world is encountered by an active imagination, as it is by each of us every day, the result is a reality that is created, rather than simply observed. The protagonist of each of these pieces comes to this realization and discovers that it produces both existential despair and self-empowerment. In the end, this paradox is central to the understanding of postmodernist art.
• #### My brother's keeper

My thesis is a young adult novel entitled 'My Brother's Keeper.' This novel is written from a first person point of view and fulfills my requirements for a Master of Fine Arts degree in creative writing, fiction emphasis. Gyle, the protagonist, is brought under the wing of Brent in a teacher-student mentor relationship that initially appears altruistic, but to Gyle's despair, he finds himself drawn further and further into the web of a sociopath. Though he tries to walk away peacefully, Brent forces a confrontation from which only one of them can survive. While technically a young adult novel, this work also fits underneath the suspense thriller, action adventure, coming of age, and psychological horror genres.
• #### Mythic women reborn: Djebar's Scheherazade & Atwood's Penelope

This thesis examines how two modern female writers approach the retelling of stories involving mythic heroines. Assia Djebar's A Sister to Scheherazade repurposes Arabian Nights to reclaim a sisterly solidarity rooted in a pre-colonial Algerian female identity rather than merely colonized liberation. In approaching the oppressive harem through the lens of the bond between Scheherazade and her sister Dinarzade, Djebar allows women to transcend superficial competition and find true freedom in each other. Margaret Atwood's The Penelopiad interrogates the idealized wife Penelope from Homer's Odyssey in order to highlight its heroine's complicity in male violence against women. Elevating the disloyal maids whom Odysseus murders, Atwood questions the limitations of sisterhood and the need to provide visibility, voice, and justice for the forgotten victims powerful men have dismissed and destroyed. The two novels signal a shift in feminist philosophy from the need for collective action to the need to recognize individual narratives. Both texts successfully re-appropriate the dominant myths they retell to propose a more nuanced and complicated view of what it means to be "Woman."
• #### Nanotribological Characterization Of Dynamic Surfaces

This dissertation research includes three fundamental areas: utilizing an atomic force microscope (AFM) to study the nanomechanical and tribological properties, to understand friction and wear at nanometer length, and to study wear mechanisms of boride coatings for biological applications. This was the first time that an AFM was used to study the nanomechanical and tribological properties and the performance of the materials. The AFM enables detailed investigation of the wear modes at multi-length scales as well as the surface mechanical properties. Surface analysis using an AFM included the surface texture, profile of indents, wear tracks, and wear scars. The friction force microscope (FFM) revealed the relationship between surface texture and frictional properties, thus contributing to the fundamental understanding of nanotribology. A new wear model was proposed. Also, hardening was discovered under the indents. The multi-scale wear study was focused on fundamental wear mechanisms. New wear modes, different than the traditional ones, were proposed. In this research, nanocracks and other damage (hardening and plastic flow) were found at different scales. Boride coatings on refractory metals were investigated for biological applications. Tribological performance of these coatings was studied in dry and wet (biofluid) conditions. It was found that boron plays an important role in forming amorphous and crystalline wear debris.
• #### Natural abundance of nitrogen(15) in a subarctic lake and biogeochemical implications to nitrogen cycling

Stable isotope ratios of nitrogen ($\delta\sp{15}$N) were employed to track the origin and fate of nitrogen in a subarctic lake, Alaska. The annual planktonic nitrogen cycle was dominated by N$\sb2$ fixation in spring and NH$\sb4\sp+$ assimilation in summer. In winter, microbial nitrification was the major sink for NH$\sb4\sp+$ and denitrification was accounted for most of the loss of NO$\sb3\sp-.$ The small isotope fractionation in nitrification is proposed as a result of substrate (NH$\sb4\sp+)$ limitation. The temporal and spatial homogeneity of the $\delta\sp{15}$N of dissolved organic nitrogen may be related to its large pool size and refractory nature. A stable isotope mass balance suggests that the winter phytoplankton was only composed of 10 to 20% of the suspended organic matter in water column due to low primary productivity during the ice cover period. A close correlation between $\delta\sp{15}$N of phytoplankton and $\delta\sp{15}$N of dissolved pools indicates that NH$\sb4\sp+$ was the predominant nitrogen source for non-N$\sb2$-fixing algae. The similarity of $\delta\sp{15}$N between a spring blue-green bloom and N$\sb2$ suggests an atmospheric origin for nitrogen. A mixing model estimated that the blue-green algal bloom derived approximately 70% of its nitrogen from molecular nitrogen. This fixed nitrogen was further transferred to higher trophic levels via the food chain and to other primary producers following mineralization. The $\delta\sp{15}$N of aquatic macrophytes indicates that non-rooted species obtained their nitrogen from the water column while rooted species obtained their nitrogen largely from the sediment. Evidence from dual isotope tracers ($\delta\sp{15}$N and $\delta\sp{13}$C) suggests that the zooplankton were supported by phytoplankton throughout the growing season despite an apparent abundance of detritus in the water column. Benthic fauna relied on either phytoplankton detritus or other organic matter in the sediment. The $\delta\sp{15}$N data exhibit only two to three trophic levels in both planktonic and the benthic communities in Smith Lake.
• #### Natural Attenuation Of Chlorinated Solvents In Subarctic Ground Water

Little is known about natural attenuation of chlorinated solvents in subarctic ground water. This study aimed to better understand the biogeochemistry and microbiology associated with naturally occurring processes of contaminant removal at two hydrologically diverse sites near Fairbanks, Alaska. Six Mile Village, located several km north of the Tanana River, is hydrologically stable, experiencing minor fluctuations in ground-water levels. Fort Wainwright is located adjacent to the Chena River and is hydrologically dynamic, experiencing seasonal flow reversals and substantial fluctuations in water-table elevations. By comparing data collected seasonally and with data collected at the two sites, I determined how ground-water/surface-water interactions affected in situ redox conditions and, hence, natural attenuation processes. A portion of the aquifer at Fort Wainwright was undergoing active treatment so I was also able to compare differences in chlorinated solvent transformations in treated and untreated ground water. Although ground water at Fort Wainwright was generally more oxidized than ground water at Six Mile Village, hydrogen concentrations at both sites were almost uniformly within ranges suggestive of iron or manganese reduction. However, aquifer sediments in the Tanana/Chena Alluvium are composed of mafic (containing reduced iron and manganese) minerals; suspended ferric iron appeared to result from oxidation of ferrous iron as ground water rose through the unsaturated zone. Sulfate concentrations were substantial and dissolved sulfide in most samples suggested that sulfate reduction might have been an important process. Calculated in situ Gibbs free energies for iron and sulfate reduction were energetically favorable at both sites; given other geochemical data, it seems likely these two processes co-occurred. Although methane was present in most samples, methanogenesis from H2 /CO2 was generally not energetically feasible at either site. Methane likely diffused from underlying permafrost or peat. The presence of less chlorinated intermediates of solvent degradation suggested that biological reductive dechlorination occurred, providing further support that sulfate-reducing conditions existed. However, low rates of microbial activity, incomplete degradation and persistence of contaminants imply that biologically mediated mechanisms did not likely represent an important contribution to natural attenuation of contaminants at either site where dilution appeared to be a major attenuation mechanism.
• #### Natural compounds isolated from wild Alaska bog blueberries intervene with molecular targets of neuroinflammation

NADPH Oxidase (NOX) has emerged as a key mediator of inflammatory processes that are prevalent in acute and chronic pathologies of the nervous system, cardiovascular system, and the immune system. Activation of NOX results in the formation of superoxide, a specific type of reactive oxygen species (ROS). Excessive accumulation of superoxide causes severe oxidative stress and ultimately, progressive cellular damage and degeneration. Despite the implications of NOX in a multitude of pathologies, pharmaceutical interventions against this molecular target remain non-existent. A diet rich in fruits and vegetables has immense health benefits beyond the high content of antioxidant compounds. Dietary intake of blueberries improves age related cognitive deficits and alleviates inflammatory damage as shown through human trials and animal studies. These findings imply that blueberries harbor specific inhibitors against molecular targets implicated in neuronal inflammation. Our investigations unveil natural compounds present in wild Alaska bog blueberries that potently inhibit NOX activity, reduce oxidative stress, and protect neuronal health in a cellular model of neuroinflammation. These studies illuminate nutrition-guided strategies as potential therapies for the prevention and intervention of neurodegeneration and cognitive decline associated with aging and with disease.
• #### Natural disturbance at the site and landscape levels in temperate rainforests of southeast Alaska

Wind disturbance in forests of southeast Alaska is poorly understood. Dynamics of canopy gaps, formed primarily by wind, were investigated in the western hemlock (Tsuga heterophylla)/blueberry (Vaccinium spp.)/shield fern (Dryopteris austriaca) plant association in northern southeast Alaska; twenty gaps were sampled at each of 3 sites. Gaps comprised about 9% of the forest area. The majority of gaps were $<$50 m$\sp2$ in area, had a diameter-to-height (D/H) $<$0.50, were created from the death of 1 or 2 gapmakers, and had experienced gap expansion. Emulating the small-scale natural disturbance regime would be best achieved if single tree selection and small group selection cuts were administered within a stand. Diffuse light levels were greatest and most variable at both the shrub and herb layers in canopy gaps, and lowest and least variable under closed canopy forest. Shrub layer light levels were positively associated with mean and median canopy gap areas. Herb layer light levels, however, were determined by the amount of light interception at the shrub layer and not by canopy gap size. Most species were robust in terms of their light requirements compared to the range of light conditions present in the understory. Sorenson Index values indicated that gaps and closed canopy forest generally were very similar in species composition. Seedling heights suggest that western hemlock and Sitka spruce seedlings benefit from the presence of canopy gaps. However, the ability of Sitka spruce to maintain itself through gap-phase replacement is limited. Techniques are needed that allow forest managers to interpret wind patterns in remote locations, at both site- and landscape-levels, and across complex topography. I demonstrated the use of circular data analysis of treefall directions as a technique to investigate wind flows at the site-level. I also demonstrated the feasibility of mapping wind flows across a large landscape of complex terrain in southeast Alaska using flagged trees, treefall directions of large-scale natural blowdowns, and treefall directions of blowdowns associated with clearcuts.
• #### Natural fracture character and distribution adjacent to the Nenana basin, central Alaska

The NE-trending Nenana basin is a Cenozoic-aged basin located in central Alaska between the Denali and Tintina fault systems. The narrow, deep basin is a current exploration target for oil and gas resources in Interior Alaska. Natural fractures were analyzed to further understand larger structural features such as faults and folds related to the structural evolution of the Nenana basin and surrounding areas. Fracture sets were measured and described on the margin of the basin at four field locations: the Fairbanks area, along the Parks Highway between Fairbanks and Nenana, and in outcrop around the Nenana and Healy areas. In addition to measuring fracture sets in outcrop and collecting oriented samples, statistical and thin section analyses were used to further analyze fracture characteristics. Calcite twin thermometry and apatite fission track analysis were used to constrain the timing and thermal evolution of the field area. Based on the orientations of observed map-scale faults, folds, and fracture sets, I divided the four field locations into two structural domains. Domain I is characterized by NE-striking faults and associated active seismicity while Domain II is dominated by E-W striking folds and faults related to the late Cenozoic development of the Northern Foothills fold-and-thrust belt. I interpret that fracture sets in Domain I are related to the evolution of high angle faulting between the Nenana basin and the Fairbanks area during Cenozoic time. In Domain II, I interpret fracture sets are related to the evolution of the fold-and-thrust belt north of the Alaska Range. By combining fracture characteristics and apatite fission track analyses I provide constraints for the timing and shear sense of larger structural features related to the opening history of the Nenana basin. Furthermore, I propose that the evolution of the Nenana basin took place in three distinct tectonic phases during the Cenozoic. The three phases represent the transition from a pure extensional setting in the Late Paleocene to oblique-extensional faulting from the Late Miocene to present day.
• #### Natural fracturing in carbonate rocks as a function of lithology and structural position in a detachment fold: examples from the northeastern Brooks Range, Alaska

Fractures in detachment folded Mississippian-Pennsylvania Lisburne Group carbonates provide insight into the distribution and character of natural fractures as a function of folding and lithology. Data from five detachment folds suggest that hinges show a higher fracture density than limbs. This study also suggests that the amount of shortening does not play a significant role in determining fracture density or uniformity of fracture orientation. A mechanical classification based on lithologic homogeneity reflects natural fracture distribution as a function of lithology more accurately than conventional lithologic classifications. Two main fracture sets were observed, a N-S set, perpendicular to fold axes, and an E-W set, parallel to fold axes. Statistical analyses suggest that E-W fracturing occurred before and during folding and that N-S fracturing occurred both before and after folding.
• #### Natural histories of Yup'ik memoirs

This thesis explores how cultural knowledge is committed to textual form and circulated within and outside of linguistically marginalized communities. Working within a Central Yup'ik context, I have focused my research on collections of Yup'ik elders' memoirs housed within the Alaska Native Language Archive. Published Yup'ik elders' memoirs offer rich descriptions of Yup'ik cultural histories, epistemologies and statements about language, the expression and inclusion of which varies based on the interactional contexts, participant frameworks and funding institutions through which they were produced. This study incorporates both Indigenous and non-Indigenous theoretical frameworks related to the process of entextualization, or text creation, and the transmission of cultural knowledge. Drawing from archival materials and interviews with participants involved in their production and circulation, I identify the relevant linguistic ideologies and participant frameworks involved in the creation of these publications or "text artifacts" and frame my analysis with respect to the following research questions: How have published memoirs of Yup'ik elders emerged as a culturally salient genre of text? Who are the primary participants in the production, publication and circulation of Yup'ik memoirs? How do issues of identity, agency, authenticity and essentialism shape the form, thematic content and circulation of Yup'ik memoirs in Alaska? This thesis seeks to identify the primary participants and ideologies contributing to the publication of Yup'ik elders' memoirs, as well as the visibility or erasure of these actors within the published text of the memoirs. I further explore the specific ways in which individual voices, tribal, political and academic institutions and their ideological goals presuppose and contribute to broader cultural processes and shape the linguistic structure and content of textual artifacts produced. Although the documentation, description and analysis of Yup'ik language and culture has received sustained attention both within and outside the academy, this project is the first to investigate the processes and participant frameworks through which traditional Yup'ik cultural knowledge is entextualized and circulated as contemporary published text. This research offers significant insights into the collaborative efforts of Native and non-Native participants in the production of Yup'ik textual materials, while also contributing to a broader understanding of ideological goals and obstacles relative to processes of entextualization within communities facing marginalization or language endangerment within, and outside of, the circumpolar north. An analysis of the participants and ideologies shaping the production and circulation of Yup'ik memoirs provides and empirical framework for understanding the relationship between text artifacts and ongoing cultural processes, and contributes to an increasingly reflexive approach to anthropological and sociolinguistic research concerning identity, authenticity and the entextualization of traditional knowledge.