Now showing items 1259-1278 of 3493

• #### Foxtail barley (Hordeum jubatum) control with propoxycarbazone-sodium and fluazifop-p-butyl in three Alaska Native grass species

Foxtail barley is one of the most detrimental weeds for the Alaska native grass seed industry. Its control is essential for improving seed production and stand longevity so producers can meet statewide seed demands. The objective of this study was to determine suitable chemical controls of foxtail barley for three different native grass species: 'Nortran' tufted hairgrass (Deschampsia caespitosa L.), 'Gruening' alpine bluegrass (Poa alpina L.), and 'Wainwright' slender wheatgrass (Elymus trachycalus L.) formerly (Agropyron pauciflorum L.). Field and greenhouse experiments were performed to identify selectivity between two herbicide compounds and the crops studied. Foxtail barley was extremely sensitive to both compounds at the 1X rate whereas 'Nortran' tufted hairgrass was tolerant of propoxycarbazone. 'Gruening' alpine bluegrass and 'Wainwright' slender wheatgrass were not tolerant of either compound at the full rate but showed greater tolerance of propoxycarbazone at the 1/2X rate. Propoxycarbazone is a potential tool for foxtail barley control in all three native grass species used for seed production in Alaska.
• #### Fracture and shakedown of pavements under repeated traffic loads

Under repeated external loads, engineering structures or objects may fail by large plastic deformation or fatigue. Shakedown will occur when the accumulation of plastic deformation ceases under repeated loads; the response of the system is then purely elastic. Fatigue and shakedown have been individually studied for decades and no attempt has been made to couple these two mechanisms in the mechanics analysis. In this study, an attempt is made to couple shakedown and fatigue in pavement mechanics analysis using numerical simulation. The study covers three main areas: fatigue, static shakedown, and kinematic shakedown analysis. A numerical approach to fatigue analysis is proposed based on elastic-plastic fracture mechanics. The amount of the crack growth during each load cycle is determined by using the J-integral curve and $\rm R\sb{-}curve.$ Crack propagation is simulated by shifting the $\rm R\sb{-}curve$ along the crack growth direction. Fatigue life is predicted based on numerically estabiished fatigue equation. The numerical results indicate that the algorithm can be applied to fatigue analyses of different materials. A numerical algorithm based on the finite element method coupled with the nonlinear programming is proposed in static shakedown analysis. In this algorithm, both the inequality and equality constraints are included in the pseudo-objective function. These constraints are normalized by the material yield stress and the reference load, respectively. A multidirectional search algorithm is used in the optimization process. The influence of finite element mesh on shakedown loads is investigated. An algorithm that utilizes eigen-mode to construct the arbitrary admissible plastic deformation path is proposed in kinematic shakedown analysis. This algorithm converts the shakedown theorem into a convex optimization problem and can be solved by using a multidirectional search algorithm. Fatigue behavior of a two-layer full-depth pavement system of asphalt concrete is analyzed using the proposed numerical algorithm. Fatigue crack growth rate is estimated and fatigue life is predicted for the system. Shakedown analyses are also carried out for the same pavement system. The comparison between the shakedown load and the fatigue failure load with respect to the same crack length indicates that the shakedown dominates the response of the pavement system under traffic load.
• #### Fracture characteristics and distribution in exposed cretaceous rocks near the Umiat anticline, North Slope of Alaska

Umiat oil field in the southeast part of the National Petroleum Reserve-Alaska is a shallow, thrust-related anticline in the northern foothills of the Brooks Range and was one of the earliest discovered oil fields on the North Slope of Alaska. Despite significant reserves of light oil, Umiat has remained undeveloped because the reservoirs are located at shallow depths within the permafrost. Recent development of horizontal drilling techniques could provide access to this shallow reservoir with a minimal surface footprint, and has caused industry to take a second look at Umiat. Fracture networks are valuable in petroleum systems because they can enhance both porosity and permeability in a reservoir and they act as migration pathways from source rocks to reservoir. At Umiat, natural fractures, if open, could enhance reservoir permeability or, if filled with cement or ice, could impede fluid flow. In order to determine the potential of fractures at Umiat, I examined core from older Umiat wells and surveyed fractures at four exposed anticlines similar to Umiat anticline. Three fracture sets were observed in the surface anticlines: an early north-south set of calcite-filled regional extension fractures that predate folding and are interpreted as due to elevated pore pressures during burial and under north-south compression; east-west oriented, unfilled hinge-parallel extension fractures that formed during folding due to outer arc tangential longitudinal strain in fold hinges; and a set of unfilled, vertical conjugate shear fractures oriented perpendicular to fold hinges that is interpreted as having developed on the fold limbs. Several natural fractures were identified in unoriented core from Umiat wells. These natural fractures dip steeply with respect to bedding and are calcite cemented and/or open. Lack of orientation data precludes assigning these fractures directly to a fracture set observed in surface exposures, but the presence of, calcite cement suggest that these fractures belong to the early, north-south oriented calcite-filled fracture set seen in nearby surface exposures. These observations suggest that production in horizontal legs could vary depending on the azimuth of the borehole. North-south, calcite-filled fractures could serve as permeability baffles and reduce flow in north-south oriented legs. Alternatively, horizontal legs that encounter the open hinge-parallel fractures or hinge perpendicular conjugate set could experience early water breakthrough or loss of circulation.
• #### Fractured reservoir potential and tectonic development of the Iniskin -- Tuxedni region, Lower Cook Inlet, Alaska

Fracture patterns can provide insight into the strain history and stress evolution of deformed strata. In southern Alaska's Cook Inlet forearc basin, hydrocarbon traps are typically fault-cored anticlines, where fractures likely aid in the migration of hydrocarbons from lower Jurassic marine strata into Cenozoic non-marine deposits. Consequently, understanding the distribution and orientation of fracture sets with respect to these structures is necessary to improving the understanding of one of Alaska's largest petroleum provinces. Furthermore, recent refinements in understanding southern Alaska's Dynamic Cenozoic tectonic evolution allow us to interpret fractures in a regional tectonic context. Despite the important role fractures likely play in the Cook Inlet petroleum system, limited work exists linking fractures to regional tectonic events and structures. The objective of chapter one is to characterize from field and remote sensing observations the orientations, distributions, and relative ages of several regionally prominent fracture sets. Field observations focus on the area of the western Cook Inlet near Augustine Volcano, north to Tuxedni Bay. Remote sensing observations expand the study area from the Alaska Peninsula in the south to Mount Spurr in the north. I identified four fracture sets—with common orientations, opening modes, and relative ages—within the sedimentary sequence that spans early Jurassic to Miocene time in the Cook Inlet forearc basin. Within the field area, these sets fall into two structural domains: 1) the Iniskin Peninsula, site of an anticline--syncline pair and reverse slip on the SW-striking Bruin Bay fault; and 2) north of Chinitna Bay, where the Bruin Bay fault strikes ~N--S and preserves primarily sinistral displacement. Chapter two is aimed at quantifying the fracture intensity of the four regional fracture sets defined in Chapter 1, which are pervasive in deformed forearc basin strata of Jurassic age in the Iniskin--Tuxedni region of the lower Cook Inlet, Alaska. I document how fracture intensity changes between the four regionally identified fracture sets of chapter one. Analysis of fracture intensity indicates that changes in fracture intensity are guided by the opening of other fractures and grain size. I also measured fractures at the thin-section scale, via back-scattered electron microscopy, to test the feasibility of using micro fracture analysis to estimate macro fracture abundance. I conclude by discussing how natural fractures could enhance sub-surface permeability for the lower Cook Inlet hydrocarbon province; and serve as migration pathways in the lower and upper Cook Inlet petroleum systems.
• #### FRAM based low power systems for low duty cycle applications

Ferro-Electric Random Access Memory (FRAM) is a leap forward in non-volatile data storage technology for embedded systems. It allows for persistent storage without any power consumption, fulfilling the same role as flash memory. FRAM, however, provides several major advantages over flash memory, which can be leveraged to substantially reduce sleep current in a device. In applications where most of the time is spent sleeping these reductions can have a large impact on the average current. With careful design sleep currents as low as 72 nA have been demonstrated. A lower current consumption allows for more flexibility in deploying the device; smaller batteries or alternative power sources can be considered, and operating life can be extended. FRAM is not appropriate for every situation and there are some considerations to obtain the maximum benefit from its use. An MSP430FR2311 microcontroller is used to measure the performance of the FRAM and how to structure a program to achieve the lowest power consumption. Clock speed and instruction caching in particular have a large effect on the power consumption and tests are performed to quantify their effect. Two case studies are considered, a feedback control system and a data logger. Both cases involve large amounts of data writes and allow for the effects of the FRAM to be easily observed. Expected battery life is determined for each case when the sample rate is varied, suggesting that average operating current for the two solutions will nearly converge when the sampling period exceeds 1000 s. For sampling periods on the order of one second operating current can be reduced from 15.4 μA to 730 nA by utilizing FRAM in lieu of flash.
• #### A Framework for teachers in education for sustainable development for upper elementary grades in the Fairbanks North Star Borough School District

Education for Sustainable Development (ESD) is a holistic approach to education that seeks to create a better world for this generation and the next. The aim of ESD is for students to gain knowledge, skills, attitudes and values that will shape the planet for a sustainable future. The United Nations has adopted 17 Global Goals as a "universal call to action to end poverty, protect the planet and ensure that all people enjoy peace and prosperity by 2030” (United Nations Development Program, 2020, para. 1). Models for sustainability look very different depending on where one lives. The context of this work is Alaska, and more specifically the Fairbanks North Star Borough. The purpose of this project is to build a website resource to aid teachers in developing a mindset toward ESD and provide locally relevant resources and curriculum aligned with the United Nations Global Goals. This project is guided by the question of how Indigenous Ways of Knowing & Culturally responsive practices can be incorporated into curriculum development alongside district standards and ESD competencies. The methods of this project seek to engage students by incorporating real-world challenges and authentic experiences into core subject areas allowing students to connect classroom learning to real life, and thus creating engaged citizens. The aims are for students to become environmentally aware, while developing life-skills including leadership, communication, collaboration, and management. By developing a sense of place and equipping students with environmental knowledge and skills they can excel at living lives which further humanity while caring for and respecting our planet and it's resources.
• #### Framing Complexity: Teachers And Students Use Of Technology In Alaska One To One Laptop Learning Environments

The topic for this dissertation is to investigate perceptions within the implementation of established one to one laptop learning programs in Alaska high schools. A primary purpose is to gain understanding of teacher and student perception of their technology use levels by establishing a level of adoption. A secondary purpose is to gain understanding of teacher perceptions regarding concerns and implementation concepts. The theoretical framework for this study used a concurrent mixed methods approach, beginning with a quantitative broad survey with supporting qualitative open-ended questions. The sample used for this study includes public high school teachers and students, who are part of a one-to-one laptop program in thirteen schools districts across Alaska. Analysis of frequencies of technology use and levels of proficiency for both students and teachers were made in areas of personal and classroom use. Teacher professional practice was also analyzed with an emphasis on professional development. Statistical analysis included analysis of variance of demographic measures and classroom use, correlation and regression of teachers' levels of proficiency. Findings indicated a mature implementation of one to one programs throughout the teacher population sample with teachers reporting high stages of concern and moderate levels of technology use focused on the students' use of technology for learning. Implementation recommendations indicated by this study include the use of a framework to measure program progress and to gather teacher voices through the life of a project, clear communication of program goals, and a professional development model suited toward teachers' needs. This study will provide a baseline of knowledge for future studies in Alaska.
• #### Frances Anne Hopkins and the George Back connection: tracking through the Canadian landscapes of two nineteenth-century artists to find where lines converge

My paper examines the artistic influence of the renowned British explorer and artist George Back on fellow Rupert's Land artist Frances Anne Hopkins, wife of Edward Hopkins, the man in charge of the Montreal Division of the Hudson's Bay Company in the mid-nineteenth century. The aesthetic gap between the two artists is wide in that Back's sketches depict a kind of terrifying wasteland quality best described as sublime. Hopkins' Canadian landscapes are colorful, on the other hand, and show people who are at ease with their surroundings. Other notable artists also documented nineteenth-century Canadian landscapes in visual images and may have had an indirect influence on Hopkins. I suggest, however, a more direct link may be made between the artists beyond the similarities drawn out of their sublime and beautiful images. My study proposes to show that influence may exist based on Hopkins' father and his Admiralty connection to Back. After a discussion on the important historical aspects coloring the artists' work, I will clarify the Hopkins family-tie relationship to Back, followed by a discussion of their art and potential evidence of influence.
• #### Freeze-thaw effect on soil microbial activity with biochar application in subarctic soils

Alaska has limited agricultural production due to extreme climatic conditions and weakly developed soils, which affect productivity. In higher latitudes, freeze-thaw cycles are common and influence soil biology and nutrient dynamics, offering a unique opportunity to investigate the use of soil amendments like biochar to enhance native biota and soil's intrinsic properties. Biochar for this study was produced from locally harvested black spruce (Picea mariana), using a fixed bed pyrolysis unit. The production of biochar was electronically controlled with temperatures kept at 550°C, and residence times manipulated by a mechanical auger, in order to yield five distinct biochar products. Chemical analyses showed differences among the biochar samples, including cation exchange capacity (CEC), micronutrients and pH. To evaluate the influence of each biochar on higher latitude native soils and biota, a response surface model was employed to design a set of experiments that measured CO₂ accumulation during a 15-day freeze -thaw cycle. Microbial activity during this experimental phase was monitored before and after freeze-thaw. Results of this study demonstrated that cultivated soils amended with biochar showed higher microbial activity before and after freeze-thaw. Forest soil on the contrary showed no significant results when amended with biochar. These results on different microbial activity were likely due to the amounts of organic carbon present in each soil type. The study serves as an evaluative tool for determining the impact that biochar may have in subarctic regions of the US that have limited agricultural potential as a result of climatic and native soil conditions.
• #### Freezing tolerance and survival experiments with various intertidal organisms from Kachemak Bay, Alaska

Intertidal organisms at high latitudes experience multiple stresses created by freezing, including ischemia, free water reduction, and distortion and destruction of cells, and in response have adapted behavioral and physiological solutions. This study examined the response of intertidal organisms in Kachemak Bay, Alaska to freezing through laboratory experiments and field studies. Mytilus trossulus, Balanus glandula, Protothaca staminea and various limpets (Lottidae) survived freezing conditions to -10 and -20°C, depending on the season. Mytilus trossulus and B. glandula survived multiple freeze events at -10°C. Seasonal freeze response was not induced by exposure to low air temperature in M trossulus. Exposure to O⁰C was not fatal to any of the species studied: M trossulus, B. glandula, P. staminea, limpets, Fusitriton oregonensis, Katharina tunicata and Leptasterias hexactis. Preliminary results suggest that M trossulus and P. staminea have an ice nucleator. Freezing avoidance may be one cause for the differences seen in seasonal distribution patterns of F. oregonensis, Nucella lima, Onchidella borealis, Siphonaria thersites and Littorina sitkana. The current study demonstrated that intertidal organisms in this region exhibit differing responses to freezing. Some organisms survive freezing conditions by freeze tolerance, while others may avoid it by moving lower in the intertidal.

• #### Freshwater growth and recruitment of Yukon and Kuskokwim River Chinook salmon: a retrospective growth analysis.

Chinook salmon Oncorhynchus tshawytscha recruitment in the Yukon and Kuskokwim (Y-K) region of western Alaska is important for subsistence and commercial harvest. Recruitment of Chinook salmon in this region has been unpredictable in recent years, and managers and subsistence harvesters are searching for answers. Chinook salmon require freshwater growth to smolt, and larger smolts are thought to have higher marine survival. In this study, I tested for correlations between freshwater growth and recruitment using measurements from scale digitizations. All analyses were conducted at the tributary scale, with one tributary representing each river system. Linear regressions were used to check for correlations between freshwater growth and Chinook salmon returns (female productivity - recruits per spawner), number and size of female spawners present, marine growth, and water temperature. Tukey multiple comparison tests and stacked bar plots were used to check for correlations between freshwater growth and the age at which females mature and between freshwater growth and early maturation. I found no direct correlation between freshwater growth and recruitment in either tributary. However, freshwater growth appears to be decreasing as time progresses. These results suggest that, while important, freshwater growth is not the factor directly limiting recruitment in either of these tributaries.
• #### From a snowflake to the snow cover: processes that shape polar and taiga snowpacks

Snowpacks found in boreal and polar regions are the most widespread types of snow in the world, covering up to 14% of the globe. In both regions, snow accumulates over a long period (6-7 months), transforming the landscape by the presence of a thin snowpack (≤70 cm), affecting the local climate, ecology, and hydrology. In the case of polar snow, wind plays a crucial role in redistributing snow, and shaping the snow surface. But in the case of the taiga snow found in the forests of the boreal regions, micro-topography and vegetation are stronger drivers of snow distribution than wind. In this dissertation, I explore the mechanisms responsible for shaping the snow surfaces in windy and in calm conditions. Collecting data at the plot scale with a terrestrial lidar, I sought explanations of the features geometry visible on the snow surfaces in grain scale physical processes. Because snow is close to its fusion temperature in this environment, its behavior at the grain scale can greatly influence its bulk properties. So finding linkages between processes occurring at the grain scale and the observable features at the plot scale may be key to furthering our understanding of snow distribution. In the first study, I found that the morphology and the occurrence of the seven known types of snow bedforms are dependent on the ability for wind to erode the surface. Erodibility is directly linked to the sintering of wind-slab grains. For this reason, every snow dune eventually turns into sastrugi. In the second study, I studied the effects of underlying topography on the accumulation of snow in calm conditions. I found that processes such as bouncing, cohesion or interlocking of snowflakes can either enhance or inhibit the smoothing of initial bumps. In the third study, I found that plant canopies affect the deposition of snow in the boreal forest. I could differentiate up to five types of canopies for their effects on snow accumulation. Despite the complexity of the canopy structures we observed, over three years, similar accumulation patterns and reactions of canopies to snow loading were seen. I was surprised to find the presence of subnivean cavities associated to plants with a size equivalent to the average snow depth.
• #### From camps to communities: Neets'ąįį Gwich'in planning and development in a pre- and post-settlement context

This study focuses on the Neets'aii Gwich'in, whose traditional territory is located in the northeastern interior of Alaska, and their experiences with planning and development. Prior to settling into permanent villages, the Neets'ąįį lived in widely scattered camps moving in relation to seasonal subsistence resources. Equipped with extensive knowledge of their country, Neets'ąįį people knew at any given time where the best places for certain animals and resources were and thus would camp closer to those areas. According to Neets'ąįį oral history, life in the "those days" was preoccupied with basic survival. Planning ahead, being prepared, and adapting to changing conditions were some of the key strategies that enabled the Neets'ąįį to survive from one generation to the next in one of the harshest climates in the world. The past 170 years has brought unprecedented change to the Neets'ąįį. The socio-economic and political context which historically defined the experience of the Neets'ąįį shifted dramatically as a result of colonization, the establishment of permanent settlements and the ensuing need for community infrastructure. Today, the Neets'ąįį are centralized in two villages, Vashrąįį K'ǫǫ (Arctic Village) and Vįįhtąįį (Venetie), located within the boundaries of the 1.8 million-acre Venetie Indian Reserve. The transition from Neets'ąįį camps to permanent communities has introduced many new needs including landfills, roads, power generation, etc. Whereas Neets'ąįį ancestors traditionally used planning as a survival strategy, their descendants today use planning to attract external investment for much needed infrastructure. This dissertation explores the ways in which the Neets'ąįį Gwich'in have engaged in planning and development in a pre- and post-settlement context.
• #### From Forest To Tundra: Historical Biogeography, Floristic Diversity And Nucleotide Variation In Balsam Poplar

The North America boreal forest extends across more than 10� of latitude from central Labrador to interior Alaska. Periods of major climate fluctuations, including glacial and interglacial cycles, drove major migrations in the Quaternary history of the boreal forest. Beringia, the unglaciated region between the Lena and Mackenzie rivers, is recognized as an important refugium for arctic plants during the last ice age, but its role for boreal trees remains controversial. The paleobotanical record indicates Populus balsamifera (balsam poplar) survived within Beringia during the last glacial. My research employed an interdisciplinary approach, combining techniques in the fields of ecology, evolution and population genetics, to reconstruct the late Quaternary migration history of balsam poplar and to describe and classify balsam poplar plant communities in the Alaskan Arctic. Chapter 1 describes the motivation for the research. Chapter 2 addresses whether a demographically-detectable population of balsam poplar was present within Beringia during the most recent ice age. I found that patterns of variation in chloroplast DNA are most consistent with the presence of a single population of balsam poplar south of the continental ice sheets through the Late Quaternary. Chapter 3 is an analysis of floristic diversity in balsam poplar communities across the Arctic Slope, Interior Alaska and the Yukon Territory and asks whether one balsam poplar-associated plant community spans the arctic and boreal regions, or if these communities differ. I found that arctic communities are dominated by arctic-alpine taxa, whereas boreal communities are dominated by boreal taxa. A strong linkage between climate and the occurrence of balsam poplar also was observed on the Arctic Slope. Chapter 4 is a study of nucleotide diversity in three nuclear loci across the range of balsam poplar. This was the first study to document geographic structure in genetic variation within the species. It also showed that diversity in three North American poplars (P. balsamifera, P. deltoides and P. trichocarpa) was substantially less than that of three Eurasian poplars (P. alba, P. nigra and P. tremula). Chapter 5 summarizes the research and points toward future research directions.
• #### Froth flotation characterization and processing plant design for the platiniferous and auriferous marine sediments of Southwestern Alaska

The purpose of this study was to characterize, and investigate the beneficiation of, the platiniferous and auriferous marine sediments of Southwestern Alaska, located near Platinum, Alaska. The majority of placer gold particles are contained in the 50 x 150 mesh size fraction, while the platinum is finer, residing in the 100 x 200 mesh size fraction. Liberated placer gold and placer platinum group metals (PGM) particles are visible to the naked eye and readily observed under a binocular microscope. Preliminary, qualitative microprobe analysis of PGM grains from the flotation concentrate showed grains of nearly pure iridium, isoferroplatinum and Pt-Rh-Ir-Fe-S-As mineralogy. Froth flotation showed that placer gold responded very well to all the collectors used, with gold recoveries of 82.7-99.8%. Flotation of platinum responded well to only potassium amyl xanthate, with a recovery of 80.4%. Results of low intensity magnetic separation showed that virtually all the liberated gold and platinum reported to the non magnetic product. A flowsheet, with estimated capital and operating costs, was developed to process 1500 tph of marine placer feed. Annualized costs per ton to process marine sediments were estimated to be $2.40 to$3.72 depending upon plant availability, 90% to 50%, respectively.
• #### Fuel penetration rates in frozen and unfrozen soils: Bethel, Alaska

Alaska fuel-storage facilities are required by law to provide secondary containment for their largest tank-volume. Secondary containment commonly includes berms, catchment basins and ditches. Fuel-penetration rates on site soils are needed to predict potential fuel-penetration depths. Field and lab tests quantified fuel-penetration rates for three site soils in Bethel, Alaska. In-situ tests following ASTM D 5093-90 allowed measurement of fuel infiltration rates using a falling-head permeameter allowed quantification of hydraulic conductivities, permeabilities and infiltration rates in frozen and unfrozen soils prepared at various moisture contents. Unfrozen samples were tested at room temperature, 19.8-24.0C̊ (67.6-75.2F̊). Fuel-penetration rates were similar regardless of moisture contents. Tests for frozen samples occurred at -4C̊ (25F̊). Fuel-penetration rates decreased as ice-saturation increased. The permeant used for each test was a Diesel #2/Jet A-50 fuel mixture (heating fuel) consisting of predominately Jet A-50.