• The interaction of Io and the Jovian magnetic field: Io's Alfven wings and particle acceleration

      Dols, Vincent (2001-08)
      Conditions for the formation of an electric field along the field lines of Jupiter crossing the satellite Io are investigated by examining the properties of Io's Alfven wave. A three-dimensional self-consistent MHD model, using a simplified magnetosphere description, illustrates the formation of this electric field and of Io's related auroral emission in the Jovian ionosphere. The Alfven wing properties between Io and Jupiter are studied with a one-dimensional MHD model and a realistic magnetosphere. Any change in the Io/Jupiter system affects the structure of the Alfven wing and likely affects the structure of Io's auroral emissions. This emission is likely structured in multi-spots and the angle between the first spot and the instantaneous projection of Io is less than 3°. In the limited context of the 1D approximation, the acceleration mechanism is expected close to Jupiter.
    • Interaction of two tributary glacier branches and implications for surge behavior

      Knowles, Christopher P.; Truffer, Martin; Larsen, Chris; Newman, David; Wackerbauer, Renate (2018-05)
      A glacier surge is a dynamic phenomenon where the glacier after a long period of quiescence, increases its velocities by up to two orders of magnitude. These surges tend to have complex interactions with tributaries, yet the role of these tributary interactions towards glacier surging has yet to be fully investigated. In this work we construct a synthetic glacier with an adjustable tributary intersection angle to study tributary interaction with the trunk glacier. The geometry we choose is loosely based on the main trunk and tributary interaction of Black Rapids Glacier, AK, USA, which last surged in 1936-1937. We investigate surface elevations, medial moraine locations, and erosive power at the bed of the glacier in response to our adjustable domain and relative flux. A nonlinear relationship between tributary flux and surface elevations is found that indicates flow restrictions can occur with geometries like Black Rapids Glacier. These flow restrictions cause increased ice thicknesses up-glacier which can lead to surges via increased stresses.
    • Interactions Among Climate, Fire, And Vegetation In The Alaskan Boreal Forest

      Duffy, Paul Arthur; Rupp, Scott (2006)
      The boreal forest covers 12 million kM2 of the northern hemisphere and contains roughly 40% of the world's reactive soil carbon. The Northern high latitudes have experienced significant warming over the past century and there is a pressing need to characterize the response of the disturbance regime in the boreal forest to climatic change. The interior Alaskan boreal forest contains approximately 60 million burnable hectares and, relative to the other disturbance mechanisms that exist in Alaska, fire dominates at the landscape-scale. In order to assess the impact of forecast climate change on the structure and function of the Alaskan boreal forest, the interactions among climate, fire and vegetation need to be quantified. The results of this work demonstrate that monthly weather and teleconnection indices explain the majority of observed variability in annual area burned in Alaska from 1950-2003. Human impacts and fire-vegetation interactions likely account for a significant portion of the remaining variability. Analysis of stand age distributions indicate that anthropogenic disturbance in the early 1900's has left a distinct, yet localized impact. Additionally, we analyzed remotely sensed burn severity data to better understand interactions among fire, vegetation and topography. These results show a significant relationship between burn severity and vegetation type in flat landscapes but not in topographically complex landscapes, and collectively strengthen the argument that differential flammability of vegetation plays a significant role in fire-vegetation interactions. These results were used to calibrate a cellular automata model based on the current conceptual model of interactions among weather, fire and vegetation. The model generates spatially explicit maps of simulated stand ages at 1 km resolution across interior Alaska, and output was validated using observed stand age distributions. Analysis of simulation output suggests that significant temporal variability of both the mean and variance of the stand age distribution is an intrinsic property of the stand age distributions of the Alaskan boreal forest. As a consequence of this non-stationarity, we recommend that simulation based methods be used to analyze the impact of forecast climatic change on the structure and function of the Alaskan boreal forest. To assess the impact climate change has on the Alaskan boreal forest, interactions among climate, fire and vegetation were quantified. This work shows that climatic signals exert the dominant influence on area burned. These results inform a simulation model to assess the historical and future states of the Alaskan boreal forest.
    • Interannual and spatial variation in the population genetic composition of young-of-the-year Pacific Ocean Perch (Sebastes alutus) in Alaskan waters

      Kamin, Lisa M.; Gharrett, Anthony J.; Heifetz, Jonathan; Tallmon, David (2010-05)
      We know little about the population structure of Gulf of Alaska (GOA) and Bering Sea rockfish, including Pacific ocean perch (POP, Sebastes alutus), and early life history information is sparse for many rockfish species. Young-of-the-year (YOY) POP were collected with surface trawls during surveys of juvenile salmon in the GOA and Bering Sea. These samples presented a unique opportunity to study POP genetics and life history. Fourteen microsatellite loci were used to characterize the genetic variation in POP collected in a total of 45 hauls over five years. The coincidence in timing and location of several collections between years allowed examination of both fine- and broad-scale geographic variation (within cohorts) as well as interannual (between cohorts) genetic variation. The geographic genetic structure of these collections was also compared to geographic structure of adult POP described in a previous study (Palof, 2008). As in the adult study, significant broad-scale geographic divergence was observed in YOY POP in the GOA. Fine-scale geographic divergence was also observed and may be the result of variable current regimes and oceanographic features at several locations. The limited amount of temporal variation observed seems to be the result of variable oceanography and fine-scale population structure rather than the influence of a sweepstakes effect. The relationship between genetic divergence and geographic separation is virtually identical in YOY and adult POP, which confirms that dispersal of POP is limited in all life stages and also demonstrates that most YOY are produced by adults that are located nearby.
    • Interannual variability of epibenthic communities in the Chukchi Sea, Alaska

      Powell, Kimberly Keeler; Konar, Brenda; Coyle, Ken; Winsor, Peter (2015-08)
      Epibenthic communities contain a wide range of organisms and serve an important role in marine ecosystems. They are involved in carbon remineralization, benthic production, and are important prey items for higher trophic levels. Arctic epibenthic communities may be experiencing significant changes in species composition, abundance, and biomass at both short and long term time scales. While epibenthic communities may be responding to long term shifts in the environment, differentiating long term trends from short term interannual variation can be problematic. The present study examined interannual differences of epibenthic communities and potential environmental drivers of their variability in the Chukchi Sea. For this, a plumb-staff beam trawl was used to sample epibenthic species composition, abundance, and biomass of the dominant invertebrate taxa at 71 stations around the Chukchi Sea during the ice free seasons of 2009, 2010, 2012, and 2013. Over the entire study area and within a smaller area with the most temporal coverage, the largest separation was between 2009 and 2013, with more difference between 2009 to 2010 than between 2012 and 2013. Crustaceans were the most significant contributors to community composition, based on abundance, and biomass. The important environmental drivers that varied along with the epibenthic community in some but not all years included bottom water temperature, salinity, dissolved oxygen, mean sediment chlorophyll a, and sediment organic matter. In contrast, sediment grain size was important in all years and, therefore, was the least likely to contribute to the biological variability among years. While these data provide a benchmark on interannual variability of epibenthic communities in the Chukchi Sea, more monitoring is essential to determine long term trends.
    • Interannual variations in the carbon to chlorophyll a ratios during the spring bloom in Prince William Sound, Alaska

      Tamburello, Kathereen Rachel (2005-05)
      The carbon to chlorophyll a ratio of phytoplankton during the spring bloom in Prince William Sound, Alaska was investigated for 3 seasons and related to major physical and chemical variables. Carbon to chlorophyll a ratios (C:Chl) were determined by two methods, based on particulate organic carbon to chlorophyll (POC:Chl) and phytoplankton cell carbon to chlorophyll (PCC:Chl). These ratios were compared to a more commonly used estimate, a fixed ratio of C:Chl, taken from literature, for the spring phytoplankton community. The hypothesis that the C:Chl ratios were significantly different between years was proven false. This research indicates that the C:Chl ratio is primarily determined by species composition of the phytoplankton community rather than external factors such as nutrients, temperature or salinity. In addition, this research indicates that the identification and enumeration method, although rarely used because it is the most time and labor intensive method, provides the best estimate of phytoplankton carbon. The mean PCC:Chl ratio for all three years was 18, and is the best fixed ratio to estimate spring phytoplankton carbon in Prince William Sound when an EI Niño is not present.
    • Intercultural mentoring: how international students identify and foster key socialization relationships

      Rossi, Elizabeth A.; Taylor, Karen M.; Richey, Jean A.; DeCaro, Peter A. (2014-05)
      Mentoring is a widely studied relationship because of the critical job it serves for socialization and integration into the university system. Mentoring relationships can serve as sources of academic, social, and emotional support. Support while adapting to a new environment can heighten overall satisfaction an individual feels as well as increase the individual's overall success. Mentoring for domestic students entering the university is clearly valuable, but becomes more complex for international students. Intercultural communication is an interaction that takes place between individuals or groups who are from different cultural backgrounds. Understanding how diverse our world is can bring better awareness to all who come to the university for learning and teaching. Also, understanding how exchange students from dissimilar countries maneuver throughout the socialization process and how mentors helped can allow organizations to encourage mentoring of international students. This understanding can help faculty and administrators formulate a process where exchange students can rapidly move through the socialization process and become integrated members of the organization. Although extant research has investigated the ways mentorship can be a helpful resource for newcomers in expediting the socialization process, this particular study looks at how those key relationships were identified and transformed over time. The scope of this research offers the University of Alaska a better understanding of different types of mentors and how they help international students. It also shows how mentorship bonds are formed and maintained over time between individuals who are from different cultural backgrounds.
    • Interdisciplinary assessment of the skate fishery in the Gulf of Alaska

      Farrugia, Thomas J.; Seitz, Andrew C.; Kruse, Gordon H.; Criddle, Keith R.; Goldman, Kenneth J.; Tribuzio, Cindy A. (2017-12)
      Skates are common bottom-dwelling fishes and valuable non-target species in Gulf of Alaska fisheries. Although there is little demand for skates in the United States, markets in Europe and Asia are fueling desires for additional fishing opportunities on skates in Alaska. Management agencies, however, have been hesitant to allow increased harvests due to the lack of information on the ecology and population dynamics of skates, and the bioeconomics of skate fisheries. Specifically focusing on the two most commonly landedskate species in the Gulf of Alaska (GOA), the big skate (Beringraja binoculata) and the longnose skate (Raja rhina), I conducted an interdisciplinary project to address these knowledge gaps. First, I advanced our understanding of the movement patterns and habitat use of skates by satellite tagging big skates in the GOA. The results show that big skates can, and likely frequently do, travel long distances, cross management boundaries within the GOA, and spend more time in deeper waters than previously thought. Second, I used the insights from the movement study to develop the first stock assessment models for skates in the GOA. This represents an important improvement in modeling, laying the groundwork for the North Pacific Fishery Management Council to move from Tier 5 (more data limited) to Tier 3 (less data limited) harvest control rules, which should lead to increased confidence with which the total allowable catch (TAC) for skates is set. Finally, I used the sustainable harvest estimates from the stock assessment models to develop a model that examined the impacts of management decisions on the profitability of skate fishing. My research provides essential information about these understudied fishes, helping to improve the sustainability and profitability of skate harvests. Incorporation of best available science regarding skate ecology, population dynamics, and bioeconomics into fishery management fosters more responsible development of skate fisheries, sustainable fishery revenues, and employment, and reduces the risk of overfishing, stock collapse, and prolonged fishery closures. It is my hope that fishery management agencies and the fishing industry make use of the new information and insights presented in this dissertation to work collaboratively towards the responsible development of skate fisheries.
    • Intermittent hypercapnia induces long-lasting ventilatory plasticity to enhance CO₂ responsiveness to overcome dysfunction

      Mosher, Bryan Patrick; Harris, Michael B.; Taylor, Barbara E.; Hueffer, Karsten; Edmonds, Brian W. (2014-05)
      The ability of the brain to detect (central CO₂ chemosensitivity) and respond to (central CO₂ chemoresponsiveness) changes in tissue CO₂/pH, is a homeostatic process essential for mammalian life. Dysfunction of the serotonin (5-HT) mechanisms compromises ventilator CO₂ chemosensitivity/responsiveness and may enhance vulnerability to pathologies such as the Sudden Infant Death Syndrome (SIDS). The laboratory of Dr. Michael Harris has shown medullary raphe' contributions to central chemosensitivity involving both 5-HT- and y-aminobutyric acid (GABA)-mediated mechanisms. I tested the hypothesis that postnatal exposure to mild intermittent hypercapnia (IHc) induces respiratory plasticity, due in part to strengthening of bicuculline- and saclofen-sensitive mechanisms (GABAA and GABAB receptor antagonists respectively). Rats were exposed to IHc-pretreatment (8 cycles of 5 % CO₂) for 5 days beginning at postnatal day 12 (P12). I subsequently assessed CO₂ responsiveness using an in situ perfused brainstem preparation. Hypercapnic responses were determined with and without pharmacological manipulation. In addition, IHc-pretreatment effectiveness was tested for its ability to overcome dysfunction in the CO₂ responsiveness induced by a dietary tryptophan restriction. This dysfunctional CO₂ responsiveness has been suggested to arise from a chronic, partial 5-HT reduction imparted by the dietary restriction. Results show IHc-pretreatment induced plasticity sufficient for CO₂ responsiveness despite removal of otherwise critical ketanserin-sensitive mechanisms. CO₂ responsiveness following IHc-pretreatment was absent if ketanserin was combined with bicuculline and saclofen, indicating that the plasticity was dependent upon bicuculline- and saclofen-sensitive mechanisms. IHc-induced plasticity was also capable of overcoming the ventilatory defects associated with maternal dietary restriction. Duration of IHc-induced plasticity was also investigated and found to last far into life (up to P65). Furthermore, I performed experiments to investigate if IHc-induced plasticity was more robust at a specific developmental period. No such critical period was identified as IHc-pretreatment induced robust respiratory plasticity when administered at all developmental periods tested (P12-16, P21-25 and P36-40). I propose that IHc-induced plasticity may be able to reduce the severity of reflex dysfunctions underlying pathologies such as SIDS.
    • International and domestic drivers of military shifts in Alaska

      Burkhart, Peter K.; Boylan, Brandon M.; Ehrlander, Mary F.; Speight, Jeremy S. (2018-05)
      Since WWII, Alaska has witnessed dramatic influxes and reductions in military personnel and funding. This thesis explores the drivers of these events. It applies two theories to analyze the trends: realist theory from international relations and the advocacy coalition framework from public policy. The thesis uses a case study framework and process-tracing to analyze three different time periods in Alaska's history: 1) World War II (1940-1945), 2) the early Cold War era (1950-1958), and 3) the immediate post-Cold War era (1993-1999). This thesis argues that the level of international threat accounts for the United States' decisions to increase or decrease its military forces, while the strength of advocacy coalitions comprised of a diverse array of actors determines the amount of military personnel and funding transferred to Alaska.
    • Internet based data collection and monitoring for wireless sensor networks

      Revuri, Venkatramana Reddy (2007-05)
      The omnipresence of the Internet and the advances in integrated circuit technologies has expanded the potential modes of communication and data collection. Adding Internet capabilities to any electronic device greatly extends the device's user interface, allowing the user to remotely configure and monitor the device over the network through the embedded web server. The embedded web server is expected to establish two-way communication and serve dynamic web pages using very limited resources. We adapted an existing embedded web server to allow remote control and monitoring of wireless sensor networks (WSN). This required establishing an interface to the WSN and developing firmware and user programs to communicate with the remote client. An interactive and flexible web-based user management interface is developed to allow the two-way interaction between the remote user and the wireless sensor network. The embedded server generates email alerts to the administrator about critical issues in the WSN, provides secure access to the WSN control modules, etc. Two embedded web servers are developed using different hardware platforms. The first solution is a low cost, energy efficient solution with somewhat limited functionality. The other uses a more powerful microcontroller-based platform and implements a fully-functional, dynamic web server with multiple web pages.
    • Interpretation of radarsat SAR scenes of Sagwon Alaska, to establish temporal, spatial and physical active layer behavior

      Lovick, Joseph Thomas (2003-05)
      Radarsat SAR images of the Kuparuk Basin in North Alaska can be used to describe the timing and characteristics of the seasonal freeze-thaw cycle and the spatial distribution of two types of Arctic Tundra. The freezing of the ground surface; decreases backscatter brightness by 3dB allowing the date of freeze-up and thaw to be established. Using Empirical Orthogonal Functions on amplitude images allows the subtle change in the brightness (during winter) of different tundra types to be enhanced, which provides a technique for discriminating between areas of Moist Acidic Tundra and Moist Non-acidic Tundra. The sand to clay ratio affects the backscatter properties of frozen soil and is inferred to cause this brightness difference. Coherence images show the dynamic nature of Arctic tundra, and low coherence limits the applicability of interferometric techniques to describe active layer heave, however, preliminary results show promise in the application of a differential interferometric technique.
    • Interpreters perspective on intercultural communication

      Seyidova, Gulchin F. (2007-05)
      Although Translation/Interpreting Studies and Intercultural Communication Studies appear to be closely related fields of studies, both seem to have ignored their potential connectedness. In Interpreting Studies, scholars and practitioners have begun to recognize that interpreters have intercultural communication functions and do not simply automatically convey messages across parties. In Intercultural Communication Studies, scholars have neglected examining intercultural communication in the interpreting context. This study explores professional Azerbaijani interpreters' lived experiences of intercultural challenges they face in the interpreting setting to help better understand both the communication processes involved in interpreting, and interpreting as a scene for intercultural communication. Conversational interviews were employed to access lived human experiences of the researcher and the co-researchers, and thematic analysis of the capta revealed four broad themes regarding intercultural challenges encountered by interpreters during interpreting: 'the interpreter is not a robot, ' 'the interpreter has her/his sex, religion, and culture, ' 'the interpreter is between two cultures, ' and 'it depends.' These themes are intertwined and point to the conclusion that cultural difference should not be ignored in the interpreting setting.
    • Interrelationship among temperature, metabolism, swimming performance and recovery in Pacific cod (Gadus macrocephalus): implications of a changing climate

      Hanna, Shannon K. (2006-12)
      Physiological constraints are suggested to contribute to the observed changes in relative abundance of Pacific cod (Gadus macrocephalus) seen in association with interdecadal changes in sea surface temperatures. To examine this concept, two experiments were conducted to determine critical swimming speed (Ucrit), rates of oxygen consumption and recovery post-exhaustion of adult cod acclimated to different temperatures. In addition, hematocrit and plasma concentrations of cortisol, metabolites and ions from resting and exhausted fish were measured to assess the impact of swim trials on fish condition. In experiment one, fish acclimated to 4°C had similar mean Ucrit (1.07 BL/s) and resting metabolic rates (35.34 mg O₂/kg⁰⁸/hr) compared to fish acclimated to 11°C fish (1.07 BL/s; 49.43 mg O₂/kg⁰⁸/hr). Similarly, concentrations of blood constituents differed little between temperature treatments; each exhibited increases in plasma cortisol and metabolites from pre- to post-swim. Experiment two illustrated few differences in rates of recovery between temperature groups (2 and 7°C). After four hours of recovery there was no evidence of plasma cortisol or metabolites returning to pre-swim concentrations in either temperature group. It seems unlikely that physiological constraints on the metabolic performance of adult Pacific cod contribute to changes in their relative abundance.
    • Interrelationships of Pacific herring, Clupea pallasi, populations and their relation to large-scale environmental and oceanographic variables

      Williams, Erik Hamilton; Quinn, T. II (1999)
      Recruitment estimates for Pacific herring, Clupea pallasi, populations in the Bering Sea and Northeast Pacific Ocean are highly variable, difficult to forecast, and crucial for determining optimum harvest levels. Age-structured population models for annual stock assessments of the sac-roe fisheries rely on fishery and survey age composition data tuned to an auxiliary survey of total biomass. In Chapter 1, the first age-structured model for Norton Sound herring was developed similarly to existing models. Estimates of variability from age-structured stock assessment models for Pacific herring are often not calculated. In Chapter 2, a parametric bootstrap procedure using a fit of the Dirichlet distribution to observed age composition data was developed as a quick and easy method for computing error estimates of model estimates. This bootstrap technique was able to capture variability beyond that of the multinomial distribution. This technique can provide estimates of variability for existing population models with age composition data requiring little change to the original model structure. Recruitment time series from Pacific herring stock assessment models for 14 populations in the Bering Sea and Northeast Pacific Ocean were analyzed for links to the environment. For some populations, recruitment series were extended backward in time using cohort analysis. In chapter 3, correlation and multivariate cluster analyses were applied to determine herring population associations. There appear to be four major herring groups: Bering Sea, outer Gulf of Alaska, coastal SE Alaska, and British Columbia. These associations were combined with an exploratory correlation analysis of environmental data in chapter 4. Appropriate time periods for environmental variables were determined for use in Ricker type environmentally dependent spawner-recruit forecasting models. Global and local scale environmental variables were examined in forecasting models, resulting in improvements in recruitment forecasts compared to models without environmental data. The exploratory correlation analysis and best fit models, determined by jackknife error prediction, indicated temperature data corresponding to the year of spawning resulted in the best forecasting models. The Norton Sound age-structured model, parametric bootstrap procedure, and recruitment forecasting models serve as enhancements to the decision process of managing Pacific herring fisheries.
    • Intertidal community development along a distance/age gradient in a tidewater glacial fjord

      Sharman, Lewis Crook (1987-12)
      Glacier Bay has recently undergone rapid deglaciation, exposing new substrates to colonization and biological development. There is a clearly defined increase in marine intertidal community development with substrate age (0-200 y) and distance (0-90 km) from present-day locations of tidewater glacier termini. The objectives of this research were (1) to describe length-of-fjord patterns of intertidal community composition and corresponding gradients of the near-surface marine physical environment and (2) to use this approach to evaluate the relative contributions of substrate age and physical factors to determining the degree of community development. Distance and age were almost perfectly correlated. Intertidal species richness increased linearly with distance/age. Environmental factors can be grouped into those that also varied linearly along this gradient, and those that varied exponentially. Distance from the glaciers and the other linearly correlated marine environmental factors of water temperature, salinity, and suspended particulate nitrogen factors are probably the most important determinants of intertidal community development.
    • Intrinsic Markers In Avian Populations: Explorations In Stable Isotopes, Contaminants, And Genetics

      Rocque, Deborah Anne; Winker, Kevin; Duffy, Lawrence K.; Ben-David, Merav; Barry, Ronald P. (2003)
      This research outlines the diversity of questions that intrinsic markers have the potential to answer and demonstrates some of these marker's limitations and successes. To test the working hypothesis that feathers grown on different continents have significantly different stable isotope ratios in commonly used markers, I analyzed stable isotopes in two generations of feathers from three species of birds that breed at high latitudes and winter on different continents. As expected, significant differences in stable isotope ratios were detected between summer- and winter-grown feathers in both plover species (Pluvialis fulva and P. domininca). However, no differences were found between the two groups of winter-grown plover feathers, despite being grown on different continents. Similarly, no differences were detected in isotope values between summer- and winter-grown feathers in northern wheatears (Oenanthe oenanthe). Large variances in isotope ratios limited the percentage of feathers correctly assigned to their origins to 41%. Atmospheric transport has been identified as the source of pollutants in several arctic ecosystems and has the potential to severely impact high-latitude populations. To determine whether long-range atmospheric transport, point sources, or migratory prey were sources of contaminants in the North Pacific, birds from two trophic levels were sampled across the longitudinal transect of the Aleutian Archipelago. Carbon isotope ratios differed among islands, thereby linking birds to island food webs and ruling out contaminant transfer through migratory prey. Patterns in some PCB congeners indicated local point sources, but significant west-to-east declines in contaminant concentrations for the majority of detected organochlorines provided evidence of long-range transport. Linking individuals to source populations using intrinsic markers has only been successful at broad scales. To determine whether increased resolution among populations could be achieved by merging multiple intrinsic marker classes, a new analytical procedure was developed. Discrete and continuous markers were combined to evaluate a Bayesian method of assignment across marker classes. For three datasets, two real and one simulated, the percentage of individuals assigned to correct source populations increased with the addition of markers and marker classes. In all cases, the maximum number of individuals was correctly assigned when all marker classes were combined.