• Do wintering conditions drive population trends in semipalmated sandpipers (Calidris pusilla)? Evidence from a corticosterone biomarker

      Boldenow, Megan L.; Powell, Abby; Kitaysky, Alexander; Lanctot, Richard (2018-05)
      Some of the most extreme long-distance migrants, Arctic-breeding shorebirds are disproportionately represented in tallies of declining species worldwide. For many shorebirds, including the semipalmated sandpiper (Calidris pusilla), the specific causes and mechanisms behind population declines have not been identified. Stressful conditions affecting birds during wintering are often implicated. Interactions between events and processes occurring in the disparate locations used throughout the annual cycle also may be critical in shaping both individual life histories and population demographics. The main objectives of my graduate research were: a) to examine whether semipalmated sandpipers wintering in specific locations incur differential levels of stress; and b) to test whether stressful conditions may carry over between different stages of an individual's life cycle. Using measurements of corticosterone (the primary avian stress hormone) deposited in winter-grown feathers, I examined the contribution of breeding season and fall migration to winter-incurred stress, and looked for evidence of carryover effects from wintering conditions to spring migration and subsequent reproductive performance. In Chapter 1, I compared the levels of stress exposure of 40 semipalmated sandpipers that bred at five Arctic sites and spent the austral summer in distinct regions (identified via light-sensing geolocators) across their tropical 'wintering' range. I found stress exposure varied by wintering region, and birds using locations along the Atlantic coast of northeastern South America and the Pacific coast of Central America had the highest feather corticosterone levels. I did not find evidence that carryover effects from the breeding season and/or fall migration influenced birds' physiology during winter. In Chapter 2, I investigated whether greater stress exposure during winter might subsequently affect birds during spring migration and/or breeding. I found that geolocator-tracked birds with increased stress levels delayed spring migration and initiated nests later. However, results for a larger dataset (including 254 birds breeding at seven sites across the North American Arctic) suggested low-stress birds nested later. It is possible the larger dataset included replacement clutches that could have confounded relationships with feather corticosterone, as only birds in better condition are likely to re-nest after clutch failure. In addition, I found evidence that stressful wintering conditions carryover to affect reproductive performance: females that accrued high levels of stress during wintering subsequently laid fewer eggs. In confirmed first nests, we found evidence for a clutch size-egg volume tradeoff, with high-stress females producing fewer offspring but potentially investing more in individual offspring. This research represents the first instance of the feather corticosterone technique being used to compare conditions across the wintering range of a calidrid shorebird and reveals specific wintering locations with high levels of stress exposure. This is also the first research that provides a mechanistic perspective on carryover effects between the wintering and breeding stages in a shorebird, through measurements of feather corticosterone. Finally, by showing that poor environmental conditions at wintering sites far from Arctic breeding areas may be detrimental to the reproductive performance of a species with declining populations, this research emphasizes the importance of considering full annual cycles in conservation and research efforts for migratory species.
    • Do you know Title IX: a sexual assault navigation tool for college students

      Napolski, Jamie; Koskey, Michael; Drew, Elaine; McGee, Sean; Ramos, Judith (2017-05)
      This paper presents a Master's Project in Cross-Cultural Studies at the University of Alaska Fairbanks (UAF) that sought to understand Alaska Native and first-year (freshman) students beliefs and behaviors about the Title IX process at UAF. Title IX is a federal law which states that no individual in the United States shall be discriminated or excluded from participation, denied the benefits or subject to discrimination, based on their sex, within any educational program or activity that receives Federal financial assistance. This project undertook a mixed-method study utilizing a survey and focus groups to identify what information students are being provided regarding Title IX, how much students understand regarding their rights and resources, and ultimately to develop a practical tool to improve students' understanding and navigation of the Title IX process. The results of the focus groups and surveys are presented and discussed. The tool includes an explanation of remedies and also where to locate resources here at the University of Alaska Fairbanks.
    • Doppler sodar observations of the winds and structure in the lower atmosphere over Fairbanks, Alaska

      Kankanala, Pavan Kumar Reddy (2007-12)
      Fairbanks, Alaska (64°49ʹ N, 147°52ʹ W) experiences strong temperature inversions which when combined with the low wind speeds prevailing during the winter cause serious air pollution problems. The SODAR (Sound Detection And Ranging) or acoustic sounder is a very useful instrument for studying the lower atmosphere as it can continuously and reliably measure the vertical profiles of wind speed and direction,vertical motions, turbulence and the thermal structure in the lower part of the troposphere. A Doppler sodar was operated from December 2005 to April 2006 at the National Weather Service site in Fairbanks. The wind observations from the sodar indicate that the majority of the winds during the winter months were from the North, Northeast or the East, which is in good agreement with the radiosonde measurements and the long term trends in the wind patterns over Fairbanks area. Case studies were carried out using the sodar data depicting drainage winds, low-level jets, formation and breakup of inversions and estimation of the mixing layer height.
    • Double-difference relocation of earthquakes at Uturuncu Volcano, Bolivia, and Interior Alaska

      Hutchinson, Laura; West, Michael; Christensen, Douglas; Freymueller, Jeffrey (2015-08)
      In order to reliably interpret seismic patterns, we must have reliable earthquake locations. To improve our catalog locations, I incorporate cross-correlations into double-difference earthquake relocations to generate high precision relative locations. I perform relocations for two regions, one volcanic and one tectonic. At Uturuncu volcano, I incorporate a wealth of previous studies to present a picture of the processes at play. Seismic, gravity, InSAR, and electromagnetic studies all show that there is a magma body underlying the entire region, and chemical studies suggest that this magma body (the Altiplano-Puna Magma Body, or APMB) is the source of the large ignimbrite eruptions that have occurred in the past. The recent uplift has been modeled as a new batch of magma rising off the APMB, beginning the ascent as a diapir. My relocation results indicate that the seismicity aligns with the top of one of the imaged low velocities zones, which I interpret as a diaper beneath Uturuncu. The earthquakes mark the depth at which the crust is cool enough for brittle deformation. I also perform cross-correlations to determine families of similar events. These families are located around the summit of Uturuncu and display a radial pattern. This suggests that they are due to local volcanic stresses, such as inflation of the volcano, rather than regional stresses. In Interior Alaska, I study a region that is very seismically active, yet has no mapped Holocene faults. There are a series of seismic zones in the area, each comprised of NNE-striking seismic lineations. I perform earthquake relocations on 40 years worth of seismicity in order to refine and interpret fault planes. I additionally examine three earthquake sequences in the Minto Flats Seismic Zone (MFSZ). These earthquakes are large enough (≥M5) to produce an aftershock sequence to map out the rupture plane. I find that two of the three earthquakes occurred on WNW-striking planes, roughly perpendicular to the dominant direction of the seismic zone. The third earthquake ruptured along a NNE-striking plane but generated a WNWESE halo of aftershocks, suggesting that the basement is highly fractured in the region. The NW pattern that I find for the three sequences falls in line with my findings for the rest of the Interior: there are a series of NE-striking faults that are cut by NW-striking faults. Throughout the Interior, these faults cross at approximately 60°, suggesting that they are conjugate faults. I believe that the three earthquake sequences in the MFSZ are also conjugate faults and are a part of the broader conjugate system throughout the Interior.
    • Down side up: representations of Down syndrome in Born This Way

      Olson, Bekah L.; May, Amy; Hum, Richard; Lazarus, Jason (2018-05)
      Stereotypical media representations of people with disabilities reinforce stigma, resulting in dehumanization. Conversely, positive representations create counter narratives that challenge stereotypes and stigmatized information disseminated by the media. While some studies have explored media depictions of people with disabilities in general, there is a lack of research focusing specifically on Down syndrome. Born This Way, a reality TV show, provides an opportunity to explore mass media depictions of Down Syndrome. Qualitative content analysis was used to understand how Born This Way constructs representations of adults with Down syndrome. Four major themes were identified. Born This Way's representation of people with Down syndrome is a departure from previous portrayals of people with disabilities. Specifically, people with Down syndrome speak for themselves and take back their narrative. Instead of dehumanizing individuals with Down syndrome, Born This Way represents people with Down syndrome as capable, independent, sexual, and multifaceted. Although Born This Way depicts differences associated with Down syndrome, these differences do not become more important than the person with Down syndrome. The portrayals in Born This Way have the ability to educate and influence viewer perceptions of people Down syndrome and positively influence viewers who have Down syndrome as well. Additionally, Born This Way seems to be offering a type of vicarious social support for parents of children with Down syndrome.
    • Dramatics in the classroom: activating and enhancing the elementary intermediate level reading curriculum

      Finnell, Sarah K.; Vinlove, Amy; Hornig, Joan; Brink-Hart, Paula (2014-07)
      Elementary classroom teachers have been using drama to teach a variety of subjects since the 1960s. There are a myriad of books on the subject to which educators can turn for ideas to use in their classrooms. Theorists and practitioners have recognized that it is not enough for teachers to simply read about and practice drama in their classrooms; they should be trained in using drama effectively. In the Fairbanks North Star Borough School District teachers are well-equipped and exposed to visual arts lessons. Nearly every school has a music program, but there remains limited training or resources teachers might use to incorporate drama into their curriculum. This project would begin to fill that gap. In this report, I outline the research that justifies the use of drama as a tool to support the reading curriculum in intermediate elementary classrooms. My final project is a set of nine lessons that can be used by any teacher to support reading comprehension skills in intermediate elementary classrooms.
    • Drawing my body nude

      Bennett, Nathan (2004-08)
      Divided into five sections that mirror mankind's fall and return to grace, Drawing My Body Nude is a modern-day examination of the Romantic notions of innocence, experience and experienced innocence. Covering a span of nearly fifteen years, the text weaves together four seemingly disparate storylines: the author's addiction to, and subsequent recovery from, pornography; his mother's enrollment in a nude drawing class at a local college; the death of his patriarchal grandfather; and his own coming of age as he and his wife raise a family of their own. The text is driven by religious (specifically Latter-Day Saint), artistic and metaphysical themes. By questioning the complex issues surrounding birth and death, human existence and the afterlife, nude art and pornography, love and lust, as well as raising children and what it means to be a child, the text is an attempt to both reconcile and understand physical and inherent beauty.
    • Drifting and directed: the post-high school plans of students from three communities in rural Alaska

      Doyle, Aaron T. (2006-12)
      Many students in Alaska's rural villages complete their secondary education without a direction for life after high school. Students consistently report high aspirations to vocational training, college, and careers that require postsecondary education, yet few end up realizing these plans. To understand this paradox, this thesis uses qualitative methods to examine the influences that shaped the post-high school plans of 49 rural Alaska Native students in three villages in western Alaska. This thesis finds that misgivings about the purpose of education, difficult choices about leaving home, a substandard education, a lack of information, and perceptions of failure all combined to create drifting students who left high school without direction. Directed students were attached to postsecondary programs that provided them with a structured script with specific guidelines to follow.
    • Dubble

      Abrams, David (2004-05)
      Set in Hollywood during the 1940s, "Dubble" is a novel about an adult midget/stuntman who goes to work for enfant terrible child actor Eddie Danger. As Eddie's personal stuntman and bodyguard, David Dubble gets drawn into a sinister plot which includes sex with older women, canine homicide and studio sabotage. Written in the rat-a-tat style of a classic screwball comedy movie but also nodding in the direction of postmodernism, the novel explores the porous boundary between reality and illusion, compounded by the fact that Eddie and Dubble are filming a Western about twin brothers-one good, one bad. With character names like Paige Turner, "Bunny" Torpor and Dubble himself, the reader inevitably enters the text on a symbolic level. My goal is to write not only an entertaining story, but also one which examines the duplicity of public versus private lives in Hollywood
    • Duckling survival and incubation behaviors in common goldeneyes in Interior Alaska

      Schmidt, Joshua Harold (2004-08)
      The lack of research on the common goldeneye (Bucephala clangula) in Interior Alaska prompted this study. My objectives were to estimate duckling survival relative to several explanatory variables and to characterize incubation behaviors in a subset of females nesting in the Chena River State Recreation Area. My estimates of duckling survival were higher than previously reported for this species: 0.65 (95% CI 0.49 to 0.82) and 0.68 (95% CI 0.58 to 0.79) for 2002 and 2003 respectively. Seasonally, duckling survival increased linearly throughout 2002, remained nearly constant in 2003, and was negatively related to daily precipitation in both years. Nest attendance patterns and incubation behaviors were not related to weather, female experience, clutch size, or day of incubation. Average number of recesses per day (2.9 ± 0.05), length of recesses (100.7 ± 1.5 min), and incubation constancy (79.8 ± 0.3%) were similar to values previously reported for this species (mean ± SE). I observed nocturnal recesses in this population. Although not previously reported for this species, these recesses may occur due to extended daylight hours during the incubation period.
    • Duff moisture dynamics in black spruce feather moss stands and their relation to the Canadian forest fire danger rating system

      Wilmore, Brenda (2001-08)
      The Canadian Forest Fire Danger Rating System's Fire Weather Index (FWI) system models 3 levels of fuel moisture within the forest floor using simple environmental inputs. Wildland fire managers in interior Alaska have expressed concern that the FWI System does not take northern latitude factors such as long day lengths and permafrost into account. During the 1999 fire season destructive sampling methods were employed to monitor moisture content throughout the feather moss profile in 3 interior Alaska black spruce stands. Measured moisture contents were compared to the FWI System's fuel moisture predictions. The FWI System followed general trends of the seasonal fuel moisture within the feather moss profile. However, the short-term response of the interior Alaska moss profile is more dynamic than the FWI System's fuel moistrue code predictions. Hydraulic properties that have been linked to bulk density may be the causative agent for the observed short-term discrepancy.
    • DUI courts: the need for standardized DUI court evaluations

      Cameron, Howard; May, Jeff; Boldt, Frank; Duke, J. Robert (2018-12)
      There have been numerous evaluations of driving under the influence (DUI) treatment courts. The evaluation process and tools vary widely. This research project reviewed seven individual courts' evaluations, including process evaluations and outcome evaluations to determine the strength of each court's evaluation. The research goal was to better understand how these courts are evaluated, the strength of those evaluation processes, and to determine what, if any, changes can and should be made to strengthen them. Presently, there are not any standardized evaluations tools for DUI treatment courts. This research concludes that evaluations should be standardized and such standardization will allow for a stronger evaluation and the ability to uniformly compare courts and court processes.
    • Dungeness crab depth distribution: effects of sea otters

      Scheding, Karen A. (2004-05)
      The distribution and abundance of Dungeness crabs in the Glacier Bay area were observed with a submersible in five bays with and three bays without sea otters. A matrix design was used with three levels of sea otter occupation and three depth categories. Goals of this study were to determine: 1) the depth distribution of crabs; 2) if depth was a refuge from sea otter predation; and, 3) the habitat of ovigerous female aggregations. Scuba was used to calibrate submersible counts and collect substrate samples; crab pots were used to confirm submersible sightings. Abiotic and biotic variables were analyzed to interpret distribution data and aggregation sites. A regional, long-term crab survey dataset was also examined. Sea otters may have decreased crab abundance in shallow waters. Two aggregations of ovigerous Dungeness crabs were observed in shallow water with sand substrate. However, only 1% of the 33 km of transects were classified as sand, suggesting that sand may be a limiting resource. No conclusions could be made about the independent effects of sea otter presence or depth due to strong interaction. Submersible observations, crab pot surveys, and marine topography together however, point towards a shift in crab depth distribution with sea otter presence
    • Dying intestate or with a will on toxic estate? an evaluation of petroleum fiscal systems and the economic and policy implications for decommissioning of onshore crude oil fields in Nigeria

      Afieroho, Erovie-Oghene Uyoyou-karo; Patil, Shirish L.; Dandekar, Abhijit; Reynolds, Douglas B.; Perkins, Robert (2018-05)
      Many giant fields in the world like the onshore fields in Nigeria which were initially discovered over half a century ago, have begun to see consistent decline in production and profit, and are gradually entering into the economic end of field life or decommissioning phase. Characteristically, in most regions with mature fields, the large multinational oil companies have begun to sell their oil fields to small indigenous companies who may not be financially robust enough to complete the decommissioning, when it occurs. Because of the pervasive societal impact of the oil industry, if an investor fails to properly decommissioning the infrastructure, a responsible government will have to pay for the proper decommissioning, else society will suffer the socioeconomic, political, health and environmental impact. Therefore, society needs to be effectively engaged in the development of a sustainable decommissioning policy framework, which is hindered if society is uninformed and lacks access to pertinent information. Currently, there is abysmal information in the public space on the cost of decommissioning liabilities of oil fields, especially in developing countries like Nigeria. The public also need simple interpretative ways to determine the vulnerability of a county or entity to decommissioning default risk and the imminence of a default risk. Furthermore, there is currently, no way to benchmark the level of maturity or level of preparedness for decommissioning phase such that countries and entities can identify their gaps to a sustainable decommissioning policy framework and define a roadmap to close the gaps. These are important challenges to vigorous public participation, which is an essential requirement for development and implementation of any sustainable public policy for a public issue like decommissioning of crude oil fields. This study adopted several research methods to develop and introduce a new cost estimating methodology that uses publicly declared cost of asset retirement obligations (ARO) to determine a plausible cost estimate range for decommissioning liabilities. It was demonstrated with Nigeria onshore crude oil fields, which it determined to have a rough order of magnitude cost estimate for decommissioning liabilities that could be as high as $3 billion. Secondly, it also introduced decommissioning coverage ratio (DCR) and decommissioning coverage ratio vector (DCRV) as new metrics to evaluate the vulnerability to and imminence of decommissioning default risk. In demonstrating these new metrics, this study determined that the imminence of and vulnerability to decommissioning default risk for the onshore crude oil fields in Nigeria, with respect to any of the available revenue streams, is high. Thirdly, it developed a graded scale maturity model for sustainable decommissioning of petroleum fields. The model described as Fairbanks maturity model for sustainable decommissioning in the petroleum industry, has five progressive levels of maturity. It leveraged the methodology used for similar maturity models developed in other industries and for business management, and a comparative analysis of level of progress in decommissioning frameworks between some countries with leading decommissioning experience in the petroleum industry, to develop the Fairbanks maturity model. Based on the Fairbanks maturity model, frameworks for sustainable decommissioning of Nigeria onshore crude oil fields were evaluated to be at Level 1, Ad hoc maturity level, which is the lowest maturity level. Recommendations to close the identified gaps were also were made. These methodologies can be applied to any petroleum producing region or entity in the world and are advancements to the frontier of knowledge in the management of decommissioning phase for petroleum fields in general and Nigeria onshore fields in particular.
    • Dynamic Assessment In A Yugtun Second Language Intermediate Adult Classroom

      Charles, Stephen Walkie; Siekmann, Sabine; Coles-Ritchie, Marilee; Brayboy, Bryan; Allen, James (2011)
      Dynamic Assessment is a new theoretical framework for language assessment, and it is particularly relevant for underrepresented languages and learners. For this study the process is investigated in the context of Yugtun second language learners at a university level. This qualitative teacher action research was a study that involved seven students enrolled in an intermediate Yup'ik language course and that comprised three DA sessions over the course of one semester. The intention in using DA was not to help learners do better on the tests but to understand their development in the language. The hope was that DA interactions would provide me with additional insights into learner knowledge and abilities while also helping them move toward more independent control over relevant features of the language. Assessments were organized as a two-stage process involving non-dynamic administration of chapter tests (targeting learner independent performance) followed by dynamic sessions. The dynamic sessions were conducted as 15-minute one-on-one interactions between each learner and the instructor the week after the tests. In order to gauge the students' ability to self-identify and correct their mistakes, their original static test was returned to them at the outset of the meeting without any corrections or grade. Students then corrected items directly on their test and were free to interact with instructor, asking questions, requesting specific forms of help, discussing problems, and so forth. Following the tenets of interactionist DA, the mediator set out with more implicit feedback and becoming more explicit as needed. However, no specific protocol was established prior to the dynamic sessions, in order to let interactions follow whatever course was needed to meet learner needs. Unassisted performance during the non-dynamic administration therefore reveals the students' actual level of development, while the dynamic session provided more in-depth understanding into the problems behind their performance and how close they were to gaining full control of the grammatical features in question. In addition, the quality of the instructor's interactions with learners served as individualized tutoring to further support their abilities. An additional data source that further highlights the study is the dialogue journal that each participant maintained. Journal-writing was incorporated as part of the assignments in the Yugtun course. I read and responded to journal entries weekly. Students were encouraged to ask questions and share their perspective of their learning and assessment experiences and to express themselves in the language of their choice. I responded to direct and indirect questions, offered praise and support, and gave corrective language feedback only when explicitly requested to by the learners. As will be made clear, dialogue journals also helped me identify learner struggles while tracking progress over time.
    • Dynamic Modeling Of The Hydrologic Processes In Areas Of Discontinuous Permafrost

      Bolton, William Robert; Hinzman, Larry (2006)
      The overarching hypothesis of this dissertation is "in the sub-arctic environment, the presence or absence of permafrost is dominant influence on hydrologic processes." The presence or absence of permafrost is the defining hydrologic characteristic in the sub-arctic environment. Discontinuous permafrost introduces very distinct changes in soil hydraulic properties, which introduce sharp discontinuities in hydrologic processes and ecosystem characteristics. Hydraulic properties vary over short and long time scales as the active layer thaws over the course of a summer or with changes in permafrost extent. The influence of permafrost distribution, active layer thaw depth, and wildfire on the soil moisture regime and stream flow were explored through a combination of field-based observations and computer simulations. Ice-rich conditions at the permafrost table do not allow significant percolation of surface waters, which result in saturated soils near the ground surface and limited subsurface storage capacity, compared to well-drained non-permafrost sites. The removal of vegetation by wildfire results in short-term (<10 years) increases in moisture content through reduced evapotranspiration. Long-term (>10 years) drying of soils in moderate to severe wildfire sites is the result of an increased active layer depth and storage capacity. A spatially-distributed, process-based hydrologic model, TopoFlow, was modified to allow spatial and temporal variation in the hydraulic conductivity and porosity of soils. By continual variation of the hydraulic conductivity (proxy for permafrost distribution and active layer thaw depth) and porosity (proxy for storage capacity), the dynamic soil properties found in the sub-arctic environment are adequately represented. The sensitivity of TopoFlow to changes in permafrost condition, vegetation regime, and evapotranspiration is analyzed. The net result of the field observations and computer simulations conducted in this research suggest the presence or absence of permafrost is the dominant influence on soil moisture dynamics and has an important, but secondary role in the stream flow processes.
    • Dynamic simulator for a grinding circuit

      Srivastava, Vaibhav; Ganguli, Rajive; Ghosh, Tathagata; Akdogan, Guven; Darrow, Margaret (2017-08)
      The grinding circuit is a primary and indispensable unit of a mineral processing plant. The product from a grinding circuit affects the recovery rate of minerals in subsequent downstream processes and governs the amount of concentrate produced. Because of the huge amount of energy required during the grinding operation, they contribute to a major portion of the concentrator cost. This makes grinding a crucial process to be considered for optimization and control. There are numerous process variables that are monitored and controlled during a grinding operation. The variables in a grinding circuit are highly inter-related and the intricate interaction among them makes the process difficult to understand from an operational viewpoint. Modeling and simulation of grinding circuits have been used by past researchers for circuit design and pre-flowsheet optimization in terms of processing capacity, recovery rate, and product size distribution. However, these models were solved under steady approximation and did not provide any information on the system in real time. Hence, they cannot be used for real time optimization and control purposes. Therefore, this research focuses on developing a dynamic simulator for a grinding circuit. The Matlab/Simulink environment was used to program the models of the process units that were interlinked to produce the flowsheet of a grinding circuit of a local gold mine operating in Alaska. The flowsheet was simulated under different operating conditions to understand the behavior of the circuit. The explanation for such changes has also been discussed. The dynamic simulator was then used in designing a neural network based controller for the semi-autogenous mill (SAG). A two-layer non-linear autoregressive (NARX) neural network with feed to the mill as exogenous input was designed using data generated by the simulator for a range of operating conditions. Levenberg-Marquardt (LM) and Bayesian Regularization (BR) training algorithms were used to train the network. Comparison of both algorithms showed LM performed better provided the number of parameters in the network were chosen in a prudent manner. Finally, the implementation of the controller for maintaining SAG mill power to a reference point is discussed.
    • Dynamics of a migratory fish population with applications to the management of sablefish in the Northeast Pacific Ocean

      Heifetz, Jonathan; Quinn, Terrance J. II (1996)
      Quantitative models are developed to describe the dynamics of an age-structured migratory fish population subject to exploitation. Migration rates are quantified, alternative ways of apportioning harvest among areas are examined, and the dynamics of a migratory population is described within the general theoretical framework of a projection matrix model. Application of these modeling efforts is within the context of the sablefish (Anoplopoma fimbria) fishery in the North Pacific Ocean. A Markov model that includes natural and fishing mortality, tag reporting and shedding rates, and migration is used to quantify migration rates of tagged sablefish among fishery regulatory areas. Estimates of annual migration rates out of an area are in the range 19-69% for small (<57 cm fork length (FL)), 25-72% for medium (57-66 cm FL), and 27-71% for large (>66 cm FL) sablefish. The predominant direction of migration along the continental slope is eastward for large sablefish and westward for small sablefish. Most estimates of migration are precise, unconfounded, and robust to perturbations of input constants. An age-structured model that includes migration is constructed to examine harvest policies for sablefish. Areal estimates of yield-per-recruit depends on the geographic distribution of recruitment. In general, when evaluated under the current annual exploitation rate of 10%, apportioning harvest among areas based on areal estimates of biomass and apportionment based on the steady-state distribution of biomass give similar results. A policy of apportionment based on a weighted moving average of areal estimates of available biomass is preferred to others. This policy adapts to current information about geographic distribution of biomass, reduces the effects of measurement error, and does not require estimates of migration probabilities for implementation. The reproduction, mortality and migration of an age-structured fish population are incorporated into a projection matrix model. The model is parameterized to include areal specificity in the stock-recruitment relationship and events such as larval dispersion that is decoupled from local reproduction. For the sablefish fishery where direction of movement is age dependent, fishing at a common rate among areas may be detrimental to the population in a given area. Area-specific fishing strategies can be devised to meet management objectives such as maintenance of areal spawning potential.
    • Dynamics of nutrient cycling on postharvested white spruce sites in interior Alaska

      Pare, David (1990)
      Various field and laboratory methods were used to characterize nutrient cycling on two mature white spruce sites, one recently harvested site and three 14-year-old harvested white spruce sites colonized by different plant communities and presenting different intensity of soil disturbance. Study sites were chosen on upland south facing sites and presented conditions of reduced environmental variability. Soil analysis showed no changes in pools of soil nutrient unless the forest floor was removed. On the other hand, some differences in the dynamics of nutrients were seen: (1) sites where the forest floor was removed showed low N mineralization rates; (2) N mineralization rates appeared faster in the surface soil of the recently harvested site than in mature white spruce sites; (3) the surface soil of sites regenerating to aspen showed the highest N mineralization rates of all 14-year-old sites. Field soil temperature, and field soil moisture content as well as N and lignin concentrations of the forest floor could not explain the differences in N mineralization rates between sites. This suggests that species colonization may influence N dynamics and that N cycling rate on regenerating sites is controlled by a small pool of rapidly cycling N. The determination of nutrient uptake and return by vegetation growing in the field indicated that nutrient cycling was much faster in 14-year-old aspen stands than on any other regenerating or mature site. The measurement of element availability with ion exchange resin bags indicated an increased leaching of nitrate, phosphate and sulfate at springtime, the second summer following harvesting. Poor correlations were obtained between conventional soil testing and ion exchange resin bag determinations. Comparisons between field and laboratory nutrient availability indices indicated that sites colonized by sprouting aspen exhibited the highest N cycling rates seen in this study. This observation makes aspen an interesting species to consider for mixed species management strategies.
    • Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia

      Andrews, Benjamin James (2004-08)
      The Ksudach Volcano KS-1 rhyodacite deposits offer an opportunity to study eruption dynamics and plume stability during a caldera-forming eruption. Stratigraphic relations indicate four phases of eruption, Initial, Main, Lithic, and Gray. Well-sorted, reverse-graded pumice fall deposits overlying a silty ash compose the Initial phase layers. The Main, Lithic and Gray phases are represented by pumice fall layers interbedded with pyroclastic flow and surge deposits (proximally) and co-ignimbrite ashes (distally). Although most of the deposit is <30 wt.% lithics, the Lithic phase layers are>50wt.% lithics. White and gray pumices are compositionally indistinguishable, however vesicle textures and microlite populations indicate faster ascent by the white pumices prior to the Gray phase. The eruption volume is estimated as 7.5 km³ magma (dense rock equivalent) and 2.4 km³ lithics. Isopleth maps indicate mass discharge rates (MDR) ranged from 5-10x10⁷ kg/s in the Initial phase to> 10⁸ kg/s in the Main, Lithic, and Gray phases. Stratigraphic, granulometric, and component analyses indicate simultaneous eruption of buoyant plumes and non-buoyant flows during the Main, Lithic and Gray phases. Caldera collapse during the Lithic phase is reflected by a large increase in lithic particles and the textural change from white to gray pumices; collapse occurred after eruption of 2/3 of the magma.