• Imagining Ityoppia: Ethiopian diaspora and Rastafarianism

      Antohin, Esther Sellassie (2005-08)
      On a very general level, this thesis explores why Ethiopians and Rastafarians - who share Ityoppi, as a general point of reference - have historically been at odds. More specifically, however, I am interested in whether the rather recent emergence of Ethiopian communities in the United States - which share experiences of diaspora and processes of "imagining from afar" with Rastafarians - has resulted in a change of Ethiopian Americans' attitude toward adherents to Rastafarianism. The main aim of this study is to give an accurate account of the Ethiopian perspective of Rastafari, which has not been articulated till the present time. To this end I first give a broad description of their arrival in the United States, and their particular diasporic experiences, which encompasses only thirty years. Finally, I explore the prevailing attitudes and perceptions of Ethiopians in the United States with respect to the Rastafarian movement. This study utilizes primary source such as interviews and surveys conducted with first and second generation Ethiopians. It employs data collected via virtual communities along with other resources on the Internet and printed publications.
    • An impact assessment of current rural Alaska village solid waste management systems: a case study

      Wilkins, William H. III; Zhang, Mingchu; Greenberg, Joshua; Mouton, Michele (2016-08)
      The purpose of this study is to examine the impacts of current and alternative solid waste management practices of two rural Alaskan villages. The EASETECH life-cycle assessment modeling tool was used to compare the current solid waste management systems for the remote villages of Kalskag and Fort Yukon across eight alternative scenarios. Annual waste generation and composition data for these two villages and data specific to processes and functions for each waste system were collected and used to modify templates within the EASETECH program to provide a life-cycle assessment for current and proposed waste management practices. The results indicate that integrated waste management practices for these remote villages may not be economically feasible or environmentally favorable. Waste management options, though limited for these remote villages, may benefit from minor system changes. These changes include transport services and burn practices that only slightly increase operating costs, but significantly reduce local social and environmental impacts. Local, accurate, and complete waste stream data could help support future management planning for the solid waste management systems of these rural villages.
    • Impact Of Freeze -Thaw On Liquefaction Potential And Dynamic Properties Of Mabel Creek Silt

      Zhang, Yu (2009)
      In the early winter of 2002 (November), the Alaska Denali earthquake (Mw=-7.9) caused significant damage in partially frozen fine-grained soil and extensive liquefaction was observed in glacial fine-grained saturated soil surface deposits near Tok, Alaska. It illustrated that there was a need to evaluate the seismic response and liquefaction potential of fine-grain soil in cold regions; however, until now most of the research on the liquefaction phenomenon and seismic response were mainly about soil in non-cold regions. The seismic response and liquefaction potential of soils in cold regions, especially those of fine-grained nature, has not been studied thoroughly and therefore is not well-understood. This document presents a laboratory study on liquefaction potential and cyclic response of fine-grained soil in cold regions. As the main features of the soil in the ground of cold regions, temperature change at below freezing temperatures or near-freezing temperatures, and the seasonal climate change were evaluated on liquefaction potential, dynamic properties, and post-cyclic-loading settlement of fine-grained soils. Increasing temperatures from near freezing to the completely thawed temperature (i.e., 24�C, 5�C, 1�C, and 0.5�C) were used to thaw the frozen Mabel Creek silt to simulate temperature change on it, or the Mabel Creek silt experienced several freezing and thawing alternating processes (i.e., 1, 2, and 4 freeze-thaw cycles) to simulate seasonal climate change. Triaxial strain-controlled cyclic tests were conducted to evaluate liquefaction potential, dynamic properties, and post-cyclic-loading settlement. Based on this limited laboratory effort, results show that in most cases, temperature rise and freeze-thaw cycles can impact: (a) liquefaction potential, (b) dynamic properties and (c) post-cyclic-loading settlement of fine-grained soils. However, there was one case exception and this is decribed in the following sentence. When a fine-grained soil was conditioned in a partially frozen state, the possibility and threat of liquefaction significantly increased.
    • The impact of HLA-DM on peptide binding to MHC class II

      Templeton, Megan; Ferrante, Andrea; Kuhn, Thomas; Hueffer, Karsten (2016-05)
      Recognition of peptides bound to class II major histocompatibility complex (MHCII) molecules by T cell receptors of CD4+ T cells initiates an adaptive immune response. Analysis of the antigen presentation pathway indicates that elements of the epitope selection process are critical to generation of the peptide repertoire presented to T cells. Antigen presentation by dedicated cells (APCs) involves the intracellular fragmentation of protein antigens by cathepsins, binding of the derived peptide epitopes to MHCII with the participation of the peptide-editing molecule HLA-DM (DM), and subsequent transport to the surface for recognition. This thesis focuses on the energetics and structural flexibility of the peptide-MHCII complex, and their correlation with DM-susceptibility, to identify the criteria associated with the selection of peptides by APCs for subsequent presentation to T cells. Using the human MHCII HLA-DR (DR), and peptides derived from influenza H3 HA305-318 as test system, it was observed that, in the absence of DM, stable peptide binding is not reached through independent contributions of single-point interactions, but is a distributive process that involves the peptide-DR groove dyad in its entirety highlighting the inherent flexibility of the binding process. Here, DM mechanism is investigated in its ability to impact structural flexibility of the complex. Analysis of release from and binding to DR of a gamut of HA-derived peptides at two different levels of pH reveals that structural stability is reduced as a consequence of DM function. The results indicate that the outcome of DM activity is favoring the endurance of complexes with limited structural flexibility.
    • Impact of specific CSR activities, executive & board diversity on equity valuations

      Williams, David J.; Little, Joseph; Baek, Jungho; Greenberg, Joshua (2018-05)
      The objective of this study is to identify the impact of specific corporate social responsibility behaviors on equity prices. This study uses fixed effect parametric and nonparametric regressions to quantify the effect of specific corporate social responsibility activities on the equity price multiples of a number of US firms from 1999 to 2009. The results of these empirical models consistently show that CEO diversity, corporate charitable giving, and work-life balance benefit plans, are associated with lower equity price multiples compared against similar firms that lack these characteristics. Additionally, board diversity and support of the LBGTQ community is associated with a positive impact on equity price multiples. This study provides evidence that individual corporate social responsibility activities can have drastic impacts on equity prices, leading the way for future research testing whether the magnitudes of these impacts are rational and in-line with their expected impact on financial performance and risk, or a deviation from the efficient market hypothesis.
    • The impact of teacher achievement emotions on the co-production of education services

      Kelly, Kimberly A.; Lardon, Cécile; Arthur, Melanie; Porter, David; Burleson, Derick (2013-08)
      Educational policy in the United States has evolved into a more intense system of accountability, resulting in an intensification of achievement emotions experienced by teachers. Two theoretical paradigms were used to analyze whether such emotions impact teacher effectiveness in the classroom: the control-value theory of achievement emotions and the theory of co-production. Path analysis was used to test the hypothesized model of teacher effectiveness. Two of the four hypothesized factors contributing to teacher achievement emotions, perceived level of control over instruction and perceived levels of student achievement, were found to be significant. The remaining two variables, attribution of responsibility for student achievement and the correlation between teachers' values and educational reforms, were non-significant. The post-hoc model removed these two non-significant factors and added additional paths from the variable teachers' perceived control to teacher's coping response and teacher effectiveness. The post-hoc model fit the data well as demonstrated by significant path.and goodness of fit scores. The path model was transferable across the study's demographic subgroups with the exception of experience level. Modifications were made to the post-hoc model for this subgroup by addressing paths to the coping response variable, and such changes resulted in a significant fit to the data for this subgroup. The results of this study underscore the need for teachers to feel in control of their teaching in order to implement effective teaching strategies. Therefore, educational policies that diminish or remove such control may impact teacher effectiveness Under No Child Left Behind legislation, schools labeled as failing progressively remove more and more control from the teacher. The findings of this study indicate that such practices may be counterproductive and instead may be contributing to the problem of undesired student achievement levels. Enhancing teachers' feelings of self-efficacy in the classroom is recommended for enhancing student achievement, as is looking at the issue through the lens of co-production. Co-production of education services posits that education is co-produced by the teacher and the student. Effective reforms in education, therefore, must address both sides of the teacher-student nexus.
    • Impacts of a top predator (Esox lucius) on salmonids in Southcentral Alaska: genetics, connectivity, and vulnerability

      Jalbert, Chase S.; Falke, Jeffrey; Westley, Peter; López, J. Andrés; Dunker, Kristine (2018-12)
      Worldwide invasion and range expansion of northern pike (pike; Esox lucius) have been linked to the decline of native fishes and new techniques are needed to assess the effects of invasion over broad geographic scales. In Alaska, pike are native north and west of the Alaska Mountain Range but were introduced into Southcentral Alaska in the 1950s and again in the 1970s. To investigate the history of the invasion into Southcentral Alaska, I identified 7,889 single nucleotide polymorphisms (SNPs) from three native and seven introduced populations in Alaska and examined genetic diversity, structure, and affinities of native and invasive pike. Pike exhibited low genetic variability in native populations (mean heterozygosity = 0.0360 and mean π = 0.000241) and further reductions in introduced populations (mean heterozygosity = 0.0227 and mean π = 0.000131), which suggests a bottleneck following introduction. Population differentiation was high among some populations (global FST = 0.424; max FST = 0.668) when compared to other freshwater fishes. I identified five genetically distinct clusters of populations, consisting of three native groups, a single Susitna River basin invasive group, and a Kenai Peninsula group, with little evidence of admixture among groups. The extremely reduced genetic diversity observed in invasive northern pike populations does not appear to affect their invasion success as the species range Southcentral Alaska continues to expand. To assess the vulnerability of five species of Pacific salmon (Oncorhynchus spp.) to the invasion, I combined intrinsic potential habitat modeling, connectivity estimates, and Bayesian networks across 22,875km of stream reaches in the Matanuska-Susitna basin, Alaska, USA. Pink salmon were the most vulnerable species, with 15.2% (2,458 km) of their range identified as "highly" vulnerable. They were followed closely by chum salmon (14.8%) and coho salmon (14.7%). Finally, analysis of the intersection of vulnerable salmon habitats revealed 1,001 km of streams that were highly vulnerable for all five Pacific salmon. This framework is easy to implement, adaptable to any species or region, and cost effective. With increasing threats of species introductions, fishery managers need new tools like those described here to efficiently identify critical areas shared by multiple species, where management actions can have the greatest impact.
    • Impacts of storm on sea ice: from case study to climate scale analysis

      Peng, Liran; Zhang, Xiangdong; Collins, Richard; Fochesatto, Javier; Polyakov, Igor (2019-12)
      Recent studies have shown that intense and long-lasting storms potentially facilitate sea ice melting. Under the background of extratropical storm tracks poleward shift, significant reductions of Arctic sea ice coverage, and thinning of sea ice thickness over the last several decades, a better understanding on how storms impact sea ice mass balance is obviously of great importance to better predict future sea ice and the Arctic climate changes. This thesis presents a multi-scale study on how storms impact sea ice, consisting of three different parts of the effort. In the first part, we examined the impacts of the 2016 summer intense storm on sea ice changes over the Chukchi Sea using ship-borne observations. The results show that the intense storm can accelerate ice melt through enhanced upper-ocean mixing and upward heat transport. The satellite-observed long-term sea ice variations potentially can be impacted by many factors. In the second part, we first explore key physical processes controlling sea ice changes under no-storm condition. We examined and compared results from 25 sensitivity experiments using the NCAR's Community Earth System Model (CESM). We found that sea ice volume, velocity, and thickness are highly sensitive to perturbed air-ice momentum flux and sea ice strength. Increased sea ice strength or decreased air-ice momentum flux causes counter-clockwise rotation of the transpolar drift, resulting in an increase in sea ice export through Fram Strait and therefore reduction of the pan-Arctic sea ice thickness. Following four tracers released over the Arctic, we found the sea ice thickness distributions following those tracers are broader over the western Arctic and becomes narrower over the eastern Arctic. Additionally, thermodynamic processes are more dominant controlling sea ice thickness variations, especially over periphery seas. Over the eastern Arctic, dynamic processes play a more important role in controlling sea ice thickness variation. Previous studies show that thin ice responds to external perturbations much faster than the thick ice. Therefore, the impacts of storms on sea ice are expected to be different compared with the western/eastern Arctic and the entral/periphery seas. In the third part, we conduct a new composite analysis to investigate the storm impact on sea ice over seven regions for all storms spanning from 1979 to 2018. We focused on sea ice and storm changes over seven regions and found storms tend to have different short-term (two days before and after storm passage), mid-term (one-two weeks after storm passage), and long-term (from 1979 to 2018) impact on sea ice area over those regions. Over periphery seas (Chukchi, East Siberian, Laptev, Kara, and Barents Seas), storms lead to a short-term sea ice area decrease below the climatology, and a mid-term sea ice increase above the climatology. This behavior causes sea ice area to have a small correlation with the storm counts from 1979 to 2018, which suggest that storms have a limited long-term impact on sea ice area over periphery seas. Both the short term and mid-term storm impacts on sea ice area are confined within a 400 km radius circle with maximum impacts shown within a 200 km radius circle. Storms over the western Arctic (Chukchi, East Siberian, and Laptev Seas) have a stronger short-term and mid-term impact on sea ice area compared with the Eastern Arctic (Barents and Kara Seas). Storms over both Atlantic and Pacific entrance regions have a small impact on sea ice area, and storms over the Norwegian, Iceland, and Greenland Seas have the smallest impact on the sea ice area. Compared to the periphery seas, storms tend to have a stronger long-term impact on sea ice area over the central Arctic. The correlation coefficients between the storm count and sea ice area exceed 0.75.
    • The implementation and evaluation of a black carbon aerosol sampler used on an unmanned aircraft during the prescribed fire experiment RxCADRE

      Craft, Tara L.; Cahill, Caherine; Douglas, Thomas; Simpson, William (2014-12)
      Black carbon (BC) aerosols impact the earth's climate by absorbing solar radiation in the atmosphere and depositing on ice surfaces and lowering the albedo of those surfaces. Black carbon aerosols have been widely studied; however, using small unmanned aircraft systems (UAS) for the airborne study of the vertical and horizontal concentrations of BC is an emerging field. Using UAS to study BC poses some challenges due to size and weight restrictions of the aircraft, as well as issues that arise when adapting ground based instrumentation for use on different aircraft. University of Alaska Fairbanks researchers successfully integrated and flew a microAeth AE-51 on a Boeing ScanEagle to measure the concentration of BC and other absorbing and scattering particles in the smoke plume from a prescribed fire experiment, RxCADRE, conducted at Eglin AFB, FL, during October and November 2012. The ScanEaglemounted microAeth successfully collected black carbon aerosols in the smoke plume. The optical particle sizing and mass loadings from an optical particle counter disagreed with the results from the microAeth, which measures absorbing aerosols. The microAeth was tested in the laboratory-using two optical particle sizers to verify the sizes and concentrations of laboratory-generated aerosols entering the instrument and determine the capabilities and limits of the instrument. The optical particle counters were used in other applications as well showing the versatility of the instruments in extreme conditions.
    • Implementation of middle school best practice in a K-8 school: a case study of the planning year for Barnette Magnet School in Fairbanks, Alaska

      Smith-Thomas, Colleen; Lipka, Jerry; Rickard, Anthony; Reyes, Maria Elena; Monahan, John (2006-12)
      This study used a case study design to investigate the planning year for Barnette Magnet School, which opened in the fall of 2005. The conversion to a K-8 school is met with some difficulty by school districts across the nation because, while there are many benefits to keeping these 7th and 8th grade adolescents in their neighborhood elementary school where supportive relationships have already been developed, the fact remains that they have different social, emotional and academic needs than either elementary or high school students. This case study seeks to examine the current research into best educational practice for this age group and to what extent the planning of the magnet school aligned with this research. The data revealed that the Magnet School, by implementing an innovative school-wide structure based on exploratory curriculum and dynamic interactions between school and community, generally did align its plans to what is considered best practice for adolescents. Several areas of weakness are identified and described.
    • Implementation of various bed load transport equations at monitoring sites along the Sagavanirktok River

      Laurio, Jenah C.; Toniolo, Horacio; Barnes, Dave; Stuefer, Svetlana (2019-05)
      In May 2015, the Sagavanirktok River in Alaska flooded, spilling over the Dalton Highway and destroying several sections of the road near the community of Deadhorse. The Alaska Department of Transportation and Public Facilities made repairs to the road and funded the University of Alaska Fairbanks, Water and Environmental Research Center (WERC), to conduct a multiyear study of hydro-sedimentological conditions on the Sagavanirktok River. Personnel from the WERC installed four monitoring stations for research purposes. The first monitoring station (DSS1) is located near Deadhorse at Milepost (MP) 405 of the Dalton Highway, the second (DSS2) is located below the Ivishak River (MP 368), the third (DSS3) is located in Happy Valley (MP 335), and the fourth (DSS4) is located at MP 318. Near each monitoring station, large pits were excavated to trap bed sediment as it moves downstream. Researchers involved in the Sagavanirktok River study have been collecting bathymetry measurements from the sediment pits since fall of 2015. The following document discusses a research project that focused on bed load transport along the Sagavanirktok River at monitoring sites DSS1, DSS2, and DSS3. Monitoring site DSS4 was not included in this study due to difficulties retrieving sediment data caused by high water levels. Sediment transport volumes measured from the test pits were compared with volume estimations calculated using Acronym (a computer program), and applying the bed load equations of Meyer-Peter and Muller, Wong and Parker, Ashida and Michue, Fernandez Luque and Van Beek, Engelund and Fredsoe, the Parker fit to Einstein’s relation, Lajeunesse et al., and Wilson, with a critical Shields value ( t #) of 0.06 and 0.03. The study results showed that in all cases the bed load transport volumes measured at sites DSS2 and DSS3 were far smaller than those calculated using the bed load transport equations. For monitoring site DSS1, a few of the bed load transport equations estimated volumes were close to those measured. The Acronym program was used only for sites DSS2 and DSS3 due to difficulties creating the grain size distribution curve at DSS1. Data show that the volumes calculated by Acronym are greater than those measured at both sites. The bed load transport equations used for the project were not applicable to the Sagavanirktok River.
    • Implementing path coloring algorithms on planar graphs

      Bross, Daniel Aven; Chappell, Glenn; Lawlor, Orion; Hartman, Chris (2017-08)
      A path coloring of a graph partitions its vertex set into color classes such that each class induces a disjoint union of paths. In this project we implement several algorithms to compute path colorings of graphs embedded in the plane. We present two algorithms to path color plane graphs with 3 colors based on a proof by Poh in 1990. First we describe a naive algorithm that directly follows Poh's procedure, then we give a modified algorithm that runs in linear time. Independent results of Hartman and Skrekovski describe a procedure that takes a plane graph G and a list of 3 colors for each vertex, and computes a path coloring of G such that each vertex receives a color from its list. We present a linear time implementation based on Hartman and Skrekovski's proofs. A C++ implementation is provided for all three algorithms, utilizing the Boost Graph Library. Instructions are given on how to use the implementation to construct colorings for plane graphs represented by Boost data structures.
    • Implications for strain accommodation in an oblique subduction zone: new paleomagnetic and geologic data from the central Aleutian arc, Alaska

      Krutikov, Lena (2006-12)
      Oblique subduction results in partitioning of strain into arc-normal and arc-parallel components, and a complex pattern of upper plate deformation. Although partitioning of strain is observed in areas of oblique subduction around the world, the kinematics of strain accommodation are poorly understood. This is particularly true in the Aleutian arc because of a paucity of geologic and geophysical data. In the Aleutian arc, models previously proposed for forearc deformation have been characterized by clockwise rotation and westward translation of discrete tectonic blocks. This study utilizes two separate datasets to help constrain these mechanisms. The first step utilizes new high-resolution multibeam sonar data that provides a first detailed look at deformational structures on the seafloor. The second step is to examine the validity of paleomagnetic data previously collected from the arc, by re-measuring samples with improved methods. The multibeam sonar data reveal dense deformational patterns on the seafloor that suggest considerable diffuse strain between block boundaries. Remeasured paleomagnetic samples produce results that are similar to previous findings, but with reduced error bars and improved resolution. Younger rocks indicate little rotation, while samples from Amchtika Island indicate greater rotation than expected.
    • Implications of pore-scale distribution of frozen water for the production of hydrocarbon reservoirs located in permafrost

      Venepalli, Kiran Kumar (2011-08)
      Frozen reservoirs are unique with the extra element of ice residing in them along with the conventional components of a reservoir. The sub-zero temperatures of these reservoirs make them complicated to explore. This study investigates reduction in relative permeability to oil with decrease in temperature and proposes a best-production technique for reservoirs occurring in sub zero conditions. Core flood experiments were performed on two clean Berea sandstone cores under permafrost conditions to determine the sensitivity of the relative permeability to oil (kro) over a temperature range of 23°C to -10°C and for connate water salinities ranging from 0 to 6467 ppm. Both cores showed maximum reduction in relative permeability to oil when saturated with deionized water; they showed minimum reduction when saturated with 6467 ppm of saline water. Theoretically, the radius of ice formed in the center of the pore can be determined using the Kozeny-Carman Equation by assuming the pores and pore throats as a cube with 'N' identical parallel pipes embedded in it. With obtained values of kro as input to the Kozeny-Carman Equation at -10°C, the radius of ice dropped from 0.145 [upsilon]rn to 0.069 [upsilon]rn when flooding, water salinity is increased to 6467 ppm. This analysis quantifies the reductions in relative permeability solely due to different formation salinities. Other parameters like fluid saturations and pore structure effects also are discussed. Fluids like deionized water, saline water, and antifreeze (a mixture of 60% ethylene or propylene glycol with 40% water) were tested to find the best flooding agent for frozen reservoirs. At 0°C, 9% greater recovery was observed with antifreeze than with saline water. Antifreeze showed 48% recovery even at -10°C, at which temperature the rest of the fluids failed to increase production.
    • The Importance of communication in land use planning for interior Alaska: a participant observation study

      Lunsford, Olivia K.; Trainor, Sarah; Veazey, Pips; Dawe, Janice (2019-04)
      Three case studies (i.e., (1) FNSB Marijuana Zoning, (2) The Joint Land Use Study, and (3) Rethinking Smith Ranch) were examined in the context of land use planning to assist the reader in understanding some of the challenges a second-class borough in Alaska faces. The researcher utilized an opportunity with the Fairbanks North Star Borough to perform a participant observation study which demonstrated the complexity in engaging and communicating with citizens of the area. The researcher identified the three following critical themes and referenced planning literature to analyze them: (1) challenges to accomplishing goals, (2) the importance of communication, and (3) potential solutions to overcoming challenges. Upon identifying the challenges experienced both during the case studies, as well as outside of the case studies, the researcher determined possible solutions to help the borough’s Department of Community Planning overcome the difficulties associated with communication and engagement of citizens.
    • Improved Membrane Filtration For Water And Wastewater Using Air Sparging And Backflushing

      Psoch, Christian (2005)
      The goal of this research was to investigate methods and techniques that enhance mass transfer through the membranes. Two general types of fluids were investigated: synthetic wastewater treated in a membrane bioreactor (MBR) and natural and simulated river water. For both fluids, a wide range of solid concentrations (up to 18 g/L) were tested. The membranes investigated were all tubular modules at pilot scale between 0.75 and 1.20 m length, with tubular diameters of 5.5--6.3 mm, 0.2 mum pore size, and membrane surface areas of 0.036--0.1 m2. For flux enhancement, two techniques were applied: air sparging (AS), and backflushing (BF). Both techniques were compared with the sponge ball cleaning method. The experimental temperature ranged between 10 and 30�C, cross-flow velocities (CFV) ranged between 0.5 and 5.2 m/s, and transmembrane pressure (TMP) ranged between 30 and 350 kPa. Research results showed, that AS was able to enhance the conventional flux over weeks to months up to factor of 4.5 for river water and a factor of 3 for wastewater. At modest CFV of 1.5--2 m/s, AS was as successful as BF. If higher CFV (up to 5.2 m/s) were supplied for BF, this technique could enhance the wastewater flux by factor 4.5. The supply of AS and BF combined was superior to the single application even at moderate CFV. The major finding of this research was that cake thickness on the membrane surface was decreased by AS, contrary to research by other authors. AS can be used as substitute aeration in MBRs, without impairing the degradation performance. The combination of AS and BF generated the least filter cake, but the lowest fouling was observed for AS. An empirical equation was proposed to calculate the viscosity in a sidestream MBR depending on reactor temperature and mixed liquor suspended solids (MLSS).
    • An improved method of ice nucleus measurement

      Shih, Chi-Fan G. (1982-09)
      Ice nuclei, which initiate the ice nucleation process at a higher temperature than the homogeneous nucleation temperature, are essential for the initiation of the ice phase in clouds. Unfortunately, no standard method has been established for the measurement of ice nucleus concentration. The filter technique is a promising candidate if the tendency for ice nucleus concentrations to decreases as the volume sampled increases can be explained. For this study, an improved ventilation method for the development of exposed filters was developed and tested. The results were compared with results obtained in a static diffusion chamber. The volume effect was observed to be less with the new dynamic system. Further work needs to be done to find the optimum flow rate in order to reduce the vapor depletion problem to a minimum. The ratio of total counts of dynamic and static system appears to be a promising evaluation index.
    • Improved Modeling Of Turbulent Transport: From Noise In Transport Models To The Parareal Algorithm Applied To Full Turbulence Codes

      Samaddar, Debasmita; Newman, David (2010)
      Turbulence and turbulent transport are ubiquitous in nature and are of fundamental importance in everything from the spread of pollution to confinement in fusion plasmas. In order to study this, turbulence models need to be as realistic as possible and one must also be able to evolve the turbulence and the profiles of the quantities of interest on transport (long) time scales. Improving turbulence simulations by the introduction of new techniques forms the basis of this research. One part of this work involved improving the performance of a 1D transport model by the addition of noise. On a more fundamental level, studying long time dynamics for turbulence simulations is very difficult even with the fastest computers available now or in the near future. To help overcome this difficulty, a new way of simulating turbulence has been presented, namely parallelizing in time. Time parallelization of a fully developed turbulent system is a new application. Parallelizing the space domain to computationally solve partial differential equations has been extensively used and is one of the most common forms of parallelization. In contrast, the Parareal Algorithm parallelizes the time domain and has been found to significantly reduce the computational wall time in many simpler systems. Despite its success in other less complex problems, it has not yet been successfully applied to a turbulent system (to the best of our knowledge). If efficiently applied, this algorithm will allow study of the turbulent transport dynamics on transport time scales - something that has heretofore been very difficult. In this work, the results of applying the Parareal Algorithm to simulations of drift wave turbulence in slab geometry in which the relative dominance of the polarization and E x B nonlinearities are tuned artificially, are presented. These turbulent systems are in many ways similar to neutral fluid turbulence models, so success of the Parareal scheme in them expands the prospect of a broader range of application to many other turbulent problems. This thesis also presents the results of a modification to the algorithm. A model to study and predict the parameters governing the convergence of the scheme is also explored.
    • Improving CubeSat downlink capacity with active phased array antennas

      Klein, Jonathan; Hawkins, Joe; Thorsen, Denise; Raskovic, Dejan (2017-08)
      Power budgets on small satellites are restricted by the limited surface area for solar panels. This limits the power available for radio communications, which constrains the downlink budget. The limited transmit power translates to low downlink data rates on small satellites. Antenna gain from directive antennas may be a power efficient way of improving the downlink budget, thereby increasing the downlink rate of small satellites. This project focuses on the design and development of a prototype low-power, electrically-steered S-band phased array RF front-end suitable for a CubeSat that could efficiently increase the EIRP, permitting higher data rates. A prototype of the array has been constructed and tested in an anechoic chamber. The four element array provides a minimum gain of 2.5 dB and average gain of 5 dB compared to a single patch antenna element with a 5W power envelope across a range of up to 60 degrees from broadside of the array.
    • Improving postsecondary transitions for students in rural Alaska: applying solution focused brief therapy in the school setting

      Elliott, Jill M.; Cook, Christine; Gifford, Valerie; Simpson, Joni (2015)
      Successful postsecondary transitions present several challenges for adolescents, and statistics show that Alaska Native youth experience additional adverse conditions and risks compared to their peers in the dominant culture. An effective intervention plan may assist rural Alaskan students in obtaining desirable education and increase opportunities for achieving personal and professional goals. This project is focused on answering the following research questions: What research has been done to show that SFBT groups could be effective in rural school settings to aid in postsecondary transitions? What components are necessary to include in an effective transition support plan for rural Alaskan students? A literature review was conducted to gain insight as to the aspects of Alaska Native culture that influence counseling outcomes, information regarding current postsecondary transition programs that are available, and the key facets of career development interventions for adolescents. This research guided the creation of a small group counseling curriculum that is grounded in the tenets of Solution Focused Brief Therapy and Family Systems Theory. The activities and discussion that are incorporated into the project target high schools in rural Alaska, and are designed to increase awareness, enhance self-efficacy, and embrace family, community and culture as vital supports in the career development process of adolescents.