Now showing items 1417-1436 of 3496

• #### Helping veterans through outreach

The present Master's project seeks to develop a better understanding of Veterans and what they are going through. Research methods include extensive data on the high suicide rates of Veterans. Veteran and service members are in need of a service to them that will address the issue of suicide and what can be done to help and eliminate this problem. The programs that need to be designed to help needs should be in locations that have Veteran populations so as to serve them with their needs. Ultimately, Veterans Affairs (VA) officials have boosted their mental health personnel and suicide hotline staff in recent years, but at this time their data does not reflect it helping Veterans getting the help that they so desperately need.
• #### Hemocyte and tissue changes by crude oil in the blue mussel Mytilus edulis

This study examines the effects of Prudhoe Bay crude oil on the number and types of circulating hemocytes, on the phagocytic response, on spawning progression, and on internal structural changes. The number of hemocytes was reduced with 4-5 week exposure to 1000 nL/L of oil; a significant number of individuals showed a higher than average cell count with longer exposure. An increase in agranulocytes in the 8-9 week control population does not occur in populations exposed to 1000 nL/L and 500 nL/L of oil for 8-9 weeks, but, the phagocytic response was significantly depressed. The Chi-square test showed that oil interferes significantly with progression of spawning. Analysis of internal tissue structure indicates that oil can affect adipogranular storage cells, vesicular tissue, and digestive tubule cells. The changes occurring in circulating hemocytes are not necessarily consistent with changes in internal morphology.
• #### Hepatitis B in Arctic ground squirrels (Spermophylus parryi): epidemiology and population biology

Using a mark-recapture design, an epidemiological investigation of Hepatitis B was performed on four colonies of Spermophylus parryi. Animals were trapped, marked and bled. Serum samples were screened for Hepatitis B markers. Program MARK was used to estimate survival rates. Prevalence rates ranged over 55% and 1999 rates were 10% higher than 1998. Vertical transmission of the virus was not observed and juveniles were unaffected by the mother's hepatitis status. Immigrants had lower prevalence rates than residents and incidence rates accelerated throughout the study. Survival was highest during the over-winter period and adult rates were lower in 1999. Recovered animals had different survival rates than other animals and survival rates of recovered animals were lower in 1999. Evidence suggests that delayed development of disease and/or environmental conditions lowered survival rates of recovered adults in 1999. Techniques that integrated epidemiology and population biology proved fruitful and worthy of further development.
• #### Herbivore-mediated effects on ecosystem processes in a near-Arctic salt marsh

Herbivores influence, and often regulate energy flow. I investigated interactions between herbivory and the foods on which geese rely while nesting and rearing their broods on the Yukon-Kuskokwim Delta in southwestern Alaska. In a captive Cackling Canada gosling (Branta Canadensis minima) experiment I decoupled the effects of seasonal declines in forage quality and availability on gosling development. An 11% decline in forage quality translated to goslings that were structurally smaller and 100 g lighter at 31 days of age. Forage availability had similar effects on gosling size, and the combined magnitude of these effects are similar to those observed in wild populations. I manipulated within-season grazing history of 'Carex subspathacea' swards within brood-rearing areas used by Black Brant geese (Branta bernicla nigricans). Spatial variation in forage quality and availability exceeded seasonal variation. Brant consumed over 95% of the annual aboveground production of these swards without any short- or apparent long-term effects on aboveground growth. Adding grazing pressure to 'C. ramenskii, ' or removing grazing pressure from 'C. subspathacea, ' resulted in a bi-directional shift in the morphology and nutritional characteristics of these sedges. The areal extent of 'C. subspathacea' increased 2 to 8% of the Tutakoke landscape with a concomitant decrease in 'C. ramenskii' meadows between 1991-1998. Brant have been increasing the carrying capacity of the Tutakoke River colony following a population decline in the early 1980's. The population has increased beginning in 1988, yet remains below historic numbers. Density-dependent effects on gosling growth accompanied the population increase initially. However, gosling mass has increased over the past decade due to herbivore-mediated increases in the areal extent of grazing lawns.
• #### Heterogeneity and bias in abundance estimates of outmigrating chinook salmon in the Chena River, Alaska

The objective was to examine bias due to heterogeneity in capture probability (p) in an abundance estimate for chinook salmon (Oncorhynchus tschawytscha) outmigrants in the Chena River, Alaska. A higher proportion of day-marked fish (21 / 636 = 0.0330) compared to night-marked fish (17 / 1724 = 0.0098; p<0.0001, α=0.05) was recaptured at the lower site in a Cormack-Jolly-Seber experiment with upper, middle and lower sites. Heterogeneity was also likely at the middle site between upper site-marked and unmarked fish. Simulations with heterogeneity confined to the middle and lower sites (i.e., due to inadequate mixing) caused small bias (<2.5%) in the upper site abundance estimate. With heterogeneity at all three sites (a subpopulation effect), the upper site estimate had 22.9% to 29.3% negative bias. Because heterogeneity observed in the Chena was probably due to inadequate mixing (related to daytime trap evasion), bias in the upper site estimate was probably small.
• #### Heterogeneity And Bias In Abundance Estimates Of Outmigrating Chinook Salmon In The Chena River, Alaska

The objective was to examine bias due to heterogeneity in capture probability (p) in an abundance estimate for chinook salmon (Oncorhynchus tschawytscha) outmigrants in the Chena River, Alaska. A higher proportion of day-marked fish (21/636 = 0.0330) compared to night-marked fish (17/1724 = 0.0098; p $<$ 0.0001, $\alpha$ = 0.05) was recaptured at the lower site in a Cormack-Jolly-Seber experiment with upper, middle and lower sites. Heterogeneity was also likely at the middle site between upper site-marked and unmarked fish. Simulations with heterogeneity confined to the middle and lower sites (i.e., due to inadequate mixing) caused small bias ($<$2.5%) in the upper site abundance estimate. With heterogeneity at all three sites (a subpopulation effect), the upper site estimate had 22.9% to 29.3% negative bias. Because heterogeneity observed in the Chena was probably due to inadequate mixing (related to daytime trap evasion), bias in the upper site estimate was probably small. <p>

• #### High latitude ionospheric effects on error rates over a geostationary satellite-to-earth transmission path at 136 mhz

Error rate data obtained for a high latitude transionospheric earth-space VHF communications channel are presented. Interpretation of these data with respect to certain ionospheric indicators has resulted in qualitative as well as quantitative correlation between the observed error rate data and F-region irregularities. Amplitude scintillation has been found to be of the most critical importance to data channel efficiency and reliability. Indications of extra-terrestriaI (i.e., solar) control have also been documented. Transionospheric propagation phenomena have been shown to give rise to adverse channel carrier/noise ratios, while waveform distortion and timing instability remain essentially unaffected. Information on channel reliability during extreme geomagnetic storms has shown that fading margins in excess of 20 dB are necessary in order to maintain channel error rates of 10⁻⁵ or better at VHF over a transionospheric channel at high latitudes.
• #### A high performance neural network javascript library

This report covers Intellect.js, a new high-performance Artificial Neural Network (ANN) library written in JavaScript and intended for use within a web browser. The library is designed to be easy to use, whilst remaining highly customizable and flexible. A brief history of JavaScript and ANNs is presented, along with decisions made while developing Intellectjs. Lastly, performance benchmarks are provided, including comparisons with existing ANN libraries written in JavaScript. Appendices include a code listing, usage examples, and complete performance data. Intellect.js is available on GitHub under the MIT License. https://github.com/sutekidayo/intellect.js
• #### High resolution sequence stratigraphy and geochemistry of middle and upper Triassic sedimentary rocks, northeast and central Brooks Range, Alaska

Triassic age rocks constitute an important sedimentary interval on the North Slope of Alaska, because they include organic-rich source rocks that generated much of the oil that accumulated in the Prudhoe Bay field. Three detailed measured sections in the northeast and north-central Brooks Range are characterized using sequence stratigraphy, chemostratigraphy, biostratigraphy and ichnofabric, allowing interpretations about the evolution of the depositional environment and general paleogeographic setting through the Middle and Upper Triassic. High resolution correlation provides insight into the timing and pattern of source rock accumulation in the Shublik and Otuk Formations. Sequence and chemo-stratigraphic analyses suggest that deposition took place on a broad, low-angle shelf under fluctuating paleoceanographic conditions. Recorded are three third order sequences, each containing a sea level rise and highstand. Glauconitic, phosphatic, and organic-rich rocks of the Shublik and Otuk Formations indicate deposition in an environment characterized by oceanic upwelling. Organic and inorganic geochemical data support interpretations concerning paleoxygenation gradients. The cerium anomaly, manganese, phosphorus, vanadium, total organic carbon, and calcium-manganese ratio indicate dominantly oxic bottom waters during the Middle Triassic, dominantly low oxygen or anoxic conditions during much of the Upper Triassic, and a return to more oxic conditions in the late Upper Triassic.
• #### High tunnel production of lettuce (Lactuca sativa) and snap beans (Phaseolus vulgaris l.) in a High Latitude location

Fairbanks, Alaska (lat. 64°49’N) has a short, variable growing season which necessitates alternative growing techniques for reliable vegetable production. Air and soil temperatures, relative humidity, light penetration, and management requirements were evaluated for a double bay high tunnel [15.8 m wide × 3.7 m high × 14.6 m long]. Mean air temperature was 0.5 °C and soil 1.2 °C higher in the high tunnel than the adjacent field, but differences varied with ventilation and heating practices. Yield and growth characteristics of lettuce (Lactuca sativa: ‘Paris Island cos’ and ‘Two Star’) and snap beans (Phaseolus vulgaris L.: ‘Concesa’ and ‘Provider’) were evaluated. Lettuce was frost hardy in the open field, prone to bolting in the high tunnel, and in general did not benefit from the high tunnel environment, except in quality due to cleanliness. ‘Concesa’ produced significantly more in the high tunnel compared with the field (P < 0.005). ‘Provider’, produced more in the high tunnel in 2006 compared to the field, but differences were not statistically significant over two seasons. The perceived benefits of high tunnel production included protection from frost, wind, pest, and rain, improved yields depending on crop and cultivar, and decreased weed emergence and moisture accumulation.
• #### High-latitude over-the-horizon radar applications

Over-the-horizon radar (OTHR) systems that operate at high-latitudes often must contend with multipath and pronounced diffusive scattering effects produced by the anisotropic, birefringent, and heterogeneous nature of the ionosphere. In this thesis, radar performance at high-latitudes is quantified and several applications for either mitigating the deleterious effects of multipath and diffusive scattering or deriving information about the state of the ionosphere are proposed. The first application is inspired by adaptive optics techniques in other fields and involves the coherent summation of the received plane wave spectrum in order to improve angular resolution and array gain. The second application involves deriving ionospheric E x B drift from applying spatial correlation analysis to ground clutter echoes. The third application is the development of a new spatial adaptive processing technique designed specifically to preserve the Doppler spectrum of angle-Doppler coupled clutter like that observed at high-latitudes.
• #### High-Resolution Paleoceanography Of The Gulf Of Alaska, Subarctic Northeast Pacific Ocean, Since The Last Glacial Maximum: Insights Into A Dynamic Atmosphere-Ocean-Ecosystem Linkage At Decadal To Millennial Timescales

Environmental conditions in the Subarctic Northeast Pacific Ocean are an important component of North American climate patterns, as well as a potential driver of Northern Hemisphere climate variability. The North Pacific Ocean is also the terminus of modern global thermohaline circulation, suggesting that paleoceanographic records from this region have the potential to preserve evidence of both climate forcing and response on regional and global scales. A suite of high-resolution marine sediment cores collected from the Gulf of Alaska margin in 2004 provide new paleoceanographic records at decadal and centennial timescales from fjord and continental slope environments. Key findings include: (i) decadal oscillations in marine productivity correlate with previously identified terrestrial records, indicative of forcing by the Aleutian Low pressure cell; (ii) the standard binary model of the modern Pacific Decadal Oscillation (PDO) as the major pattern of ocean-atmosphere variability is insufficient to describe the full range of Holocene paleoenvironmental fluctuations observed in Gulf of Alaska records of marine productivity, freshwater discharge, and bottom-water anoxia; (iii) the North Pacific ecosystem is a sensitive recorder of abrupt climate events observed in global records; and (iv) the fjords of Southeast Alaska contain a detailed record of volcanic activity and fallout events useful for developing composite chronological models of sedimentation that correlate with other regionally important stratigraphic records. Collectively, the results presented here will potentially redefine current theoretical models of atmosphere-ocean-ecosystem variability in the North Pacific Ocean, as well as contribute to a growing body of high-resolution paleoenvironmental time-series datasets from the high latitudes.
• #### Highland Hunters: Prehistoric Resource Use In The Yukon-Tanana Uplands

The purpose of this study was to conduct a first approximation of explorations and excavations throughout the White Mountain and Steese Conservation areas during the summer field seasons of 2010 and 2011 in the Yukon Tanana Uplands. An analysis of the lithic artifacts from five site excavations (the Big Bend, Bachelor Creek, Bear Creek, US Creek and Cripple Creek) was then undertaken. These assemblages were then examined and modeled using risk-assessments, optimal resource use, and behavior processes in order to explore the interdependence of environment, ecology, and material culture that drove prehistoric subsistence cycles in this area. This archaeological research will supplement ethnographies to indicate patterns of change in landscape value, trade networks, and local economic strategies.
• #### Highlighting School of Education successes to build community

The project is a WordPress site to showcase faculty and students. This site is a companion piece to the redesigned University of Alaska Fairbanks School of Education website. It is intended to provide a visual resource to be used by faculty and staff to promote the uniqueness of current and recent developments in the School o f Education. The site should serve as a space where staff and faculty may promote opportunities for current and recent graduates. It will also include graduate students’ experiences via research, projects, career stories and testimonials provided by students. These materials will be linked in from the School of Education website under the proposed title of Showcase.
• #### Histone H2A-S122 is required for nuclear and mitochondrial genome stability

Organization and maintenance of the mitochondrial and nuclear genomes are vastly different, yet I have shown that a single serine in the H2A C-terminal tail (H2A-S122) is critical for stability of both genomes in the budding yeast, Saccharomyces cerevisiae. Phosphorylation of H2A-S 122 has previously been implicated in the spindle assembly checkpoint (SAC), however I show that by mutating the serine to an alanine (H2A-S122A), the resulting aneuploidy occurs at a much higher rate than is observed by deleting its immediate downstream kinase BUB1. Furthermore, the H2A-S122A mutant displays an increased susceptibility to DNA damaging agents that is not observed in bubΔ1 deletion cells. Our studies also implicate H2A-S122 as critical to the maintenance of the mitochondrial genome, as upon introduction of the H2A-S122A mutation, cells rapidly lose their mitochondrial genomes.
• #### Historical archaeology of Alaskan placer gold mining settlements: Evaluating process-pattern relationships

The objective of this research is to explicate appropriate methods for investigating relationships between past historical processes and variables, and resulting contemporary patterns in archaeological and historical data sets. Turn-of-the-twentieth century placer gold mining in interior Alaska is used as a case study to evaluate these relationships. By linking observable patterns in historical data sets with the variables and processes that in part create and shape them, a more-complete, context-specific explanation of past events and actions emerges when the data are evaluated in specific historical settings. The methodological approach used here is to just formulate explicit "expectations," and then to evaluate them against independent Alaskan historical and archaeological data sets. The expectations derive from independent comparative historical geographical, and archaeological research. One series of nine expectations evaluates attributes of artifacts relating to site and feature abandonment processes relating to curation and scavenging, including specific traits of artifacts in curated and scavenged deposits; the changing effects of continued curation and scavenging on an artifactual assemblage through time; and spatial characteristics of artifacts within curated and scavenged foundations. Four types of data are used evaluate the expectations, including the size of artifacts, whether they are still functional or usable, their spatial provenience within excavated structures, and a feature's data range. Seven of these expectations are corroborated, one is falsified, and one requires further data for a full evaluation. A second series of seven expectations examines aspects of placer gold mining settlement and transportation systems, including the core-peripheral relationship between Alaska and the United States; the nature of expansion of gold mining settlements into new areas; locational, demographic, and physical layout characteristics of settlement systems; the mining settlement hierarchy and its changing components through time; and characteristics of the supporting transportation supply system. These expectations, while also corroborated by the Alaskan data, lend themselves more to historical context-specific understanding and interpretation, as opposed to the strict corroboration-falsification dichotomy of the abandonment analyses.