• Crude oil bioremediation in Arctic seashore sediments

      Sharma, Priyamvada; Schiewer, Silke; Trainor, Thomas; Schnabel, William (2015-08)
      Oil is an important energy source but also an environment pollutant. Crude oil spills along Arctic shorelines might occur due to the expected increase in offshore oil production. To reduce adverse effects on the environment in the case of a spill, it is important to develop approaches to remove spilled oil. Bioremediation with addition of nutrients has shown promising results in enhancing oil degradation rates. This research focuses on determining the effect of different environmental conditions on the rate of crude oil biodegradation in laboratory experiments, as a proxy for oil spills at Arctic seashores. Laboratory microcosms were set up containing beach sediments collected from Barrow, spiked with North Slope Crude. These microcosms were incubated at varying temperatures (3°C vs. 20°C), salinities (30 vs. 35 g/L) and crude oil concentrations (1 vs. 5 mL/kg), all with a standard concentration of nutrients. Measurements of respiration rates (breakdown of hydrocarbons to CO₂), hydrocarbons remaining in the sediment (GC/FID), and hydrocarbons volatilized and sorbed to activated carbon (GC/MS) were performed. In all microcosms, higher respiration rates by naturally occurring microorganisms were observed at 20ºC compared to 3°C. Surprisingly, volatile organic compounds (VOC) release was similar at both temperatures, for different crude oil concentration and salinities. High total petroleum hydrocarbon (TPH) levels remained at 3°C for microcosms with high initial crude oil concentration. Regardless of temperature, increased salinity had a positive impact on the rate of crude oil removal, i.e. high CO₂ release, high VOC production and low amount of TPH in sediments. At higher crude oil dosages, a larger amount of volatiles was released, however CO₂ production did not significantly increase with the contaminant concentration. The results of this study will assist decision-makers in choosing effective spill response strategies for future crude oil spills in Arctic shorelines.
    • Crustal and upper mantle velocity structure in Alaska

      Searcy, Cheryl Kaye; Christensen, Douglas; Layer, Paul; Stringer, William; Kawasaki, Koji; Stone, David (1996)
      The crustal and upper-mantle velocity structure of Alaska testifies to a complex tectonic framework. Much of the structure and history of this framework remains to be conclusively determined. This thesis presents the results of three independent investigations of velocity structure in Alaska in an attempt to provide some insight into its tectonic development. The first study involved the analysis of receiver functions to determine velocity structure beneath College Station (COL), located in Fairbanks, Alaska. Receiver functions from several back azimuths facilitate a fairly detailed analysis of deep crustal velocity structure beneath COL, including an indication that Moho dips to the northeast. The second study also employed receiver function methods to investigate velocity structure for four temporary three-component seismic stations placed in the Brooks Range. Due to the short deployment of these stations in the Brooks Range only a rough estimate of crustal velocities were obtained. Nevertheless, crustal thickening beneath the Brooks range is clearly indicated by an increase in the depth to Moho. The final study undertaken was a three-dimensional tomographic P-wave velocity inversion for the subduction zone region of south central Alaska. Data for the tomographic inversion consisted of local and teleseismic ray paths. The resulting velocity perturbations indicate a positive velocity anomaly associated with the subducting Pacific plate. Furthermore, the tomographic images clarify physical characteristics of the subducting plate such as structure, thickness, and depth of penetration into the mantle.
    • Crustal Deformation Along The San Andreas Fault And Within The Tibetan Plateau Measured Using Gps

      Chen, Qizhi; Freymueller, Jeffrey T. (2002)
      Using the Global Positioning System (GPS), we study crustal deformation along the San Andreas Fault (SAF) in the San Francisco Bay area and within the Tibetan Plateau, and provide new constraints for the kinematics of these actively deforming plate boundaries. GPS measurements in 1996 and 1997 and Electronic Distance Measuring (EDM) data from the 1970s and 1980s at sites along the SAF in northern California were used to determine the near-fault strain rate and to investigate the slip rate, locking depth, and rheology. We found a pronounced high near-fault shear strain rate that can be explained by a 2-D inhomogeneous model in which a low-rigidity compliant zone concentrates strain near the fault. We suggest that the materials on either side of the fault and the cumulative fault offset play a role in the development of the compliant zone. If such a compliant zone is present but unmodeled, the geodetic estimates of slip rate and locking depth (seismogenic depth) would be biased. This would lead to a miscalculated seismic hazard. Thirteen GPS sites in southern Tibet, surveyed in 1995, 1998 and 2000, were merged with other data from China and Nepal into a single, self-consistent velocity field. The Himalaya and southern Tibet was modeled using a kinematically-consistent block model and elastic dislocation theory. We show a significantly lower convergence rate between India and Eurasia in central Himalaya than that previously estimated. We observe that southern Tibet undergoes non-uniform (spatial) east-west extension with one-half of the extension across the Yadong-Gulu rift. We infer that spatially non-uniform extension in southern Tibet results in variation of the arc-normal convergence rates along the Himalaya, and that the Yarlung-Zangbo suture or adjacent structure may be active as a right-lateral strike slip fault. From 44 GPS sites in the Tibetan Plateau, we show that deformation of Tibet is distributed and strain accumulation is spatially uniform across the entire plateau. We propose a kinematic model for the Tibetan Plateau to be a combination of rigid block motion, pure shear and uniaxial contraction in the direction of about N32�E, comparable to the convergence direction between India and Eurasia.
    • Crustal Deformation In Alaska Measured Using The Global Positioning System

      Fletcher, Hilary Jane; Freymueller, Jeffrey T. (2002)
      Repeat observations using the Global Positioning System at sites on the Earth's surface enable the velocity of those sites to be estimated. These velocity estimates can be used to model the processes of the crust's deformation by faulting and folding. The focus of this study is crustal deformation in Alaska and in particular the region of interior Alaska within 300km of Fairbanks, including the Denali fault; the Fairweather fault and Yakutat block in southern Alaska; and the Semidi region of the Aleutian arc. This deformation is driven by the relentless northwestward motion of the Pacific plate relative to North America. The Yakutat block, an allocthonous terrane located in the 'armpit' of southern Alaska is shown to be moving at neither the Pacific Plate rate nor is it attached to North America. Instead it has a velocity parallel to the Fairweather fault, which means that some offshore structure, possibly the Transition Zone, must accommodate some of the Pacific-North American relative motion. The slip on the Fairweather fault is estimated to be 44 +/- 3 mm/yr with a locking depth of 8 +/- 1 km, which implies a recurrence time of ~80 years for an MS 7.9 earthquake. Using a model of southern Alaska block rotation with the Denali fault as the northern boundary, the slip rate on the McKinley segment of the Denali fault is estimated to be ~6--9 mm/yr for a locking depth of 12 km. Moving to the southwest, data from sites in the Semidi segment of the Alaska subduction zone, between the fully-coupled segment to the northeast and the slipping Shumagin segment to the southwest are studied. This region, which sustained a magnitude 8.2 earthquake in 1938, is determined to be highly coupled and accumulating strain. Finally, all of these pieces are connected in a quantitative model for southern Alaska. This model involves three crustal blocks, the Yakutat block, Fairweather block and southern Alaska block, which lie between North America and the Pacific plate and move relative to these major plates.
    • Crustal Thickness Variation In South Central Alaska: Results From Broadband Experiment Across The Alaska Range

      Veenstra, Elizabeth (2009)
      The Broadband Experiment Across the Alaska Range (BEAAR) was a passive source seismic study in which 36 three-component broadband seismic stations were deployed over a period of 27 months to collect high quality data to study the Alaska Range and perhaps elucidate tectonic processes. The wavetrain of a teleseismic body wave may be interpreted in terms of reflection and transmission of waves converted at discontinuities. The recorded signal may be regarded as a convolution of the source-time function, the receiver function, and the instrument response. A receiver function is the contribution to the seismic waveform recorded at a single station due to the response of local crustal structure, and can be inverted for vertical velocity structure beneath the three-component broadband seismic station. Receiver function analyses reveal typical crust beneath the lowlands north of the Alaska Range is 26 km thick, while beneath the mountains typical crust is 35--45 km thick. Receiver function analysis of ~15,000 teleseismic waveforms recorded by BEAAR broadband seismometers provided over 100 crustal thickness data points. Similarity between crustal thicknesses determined from receiver function analysis and crustal thicknesses predicted from topography assuming Airy isostasy indicate the observed crustal root is sufficient to support the Alaska Range. North of the range, however, the crust is systematically thinner than predicted by simple Airy isostasy. A crustal density contrast of 4.6% across the Hines Creek Fault 2700 kgm-3 to the north and 2830 kgm-3 to the south, explains the observed difference between the crustal thicknesses predicted by simple Airy isostasy and the crustal thicknesses determined by receiver function analysis. Our results indicate that variations in both crustal thickness and density are required to explain the seismic and gravity data. Crustal thicknesses across the central Alaska Range suggest that these mountains are supported by a crustal root developed due to contractional thickening. Crustal thickness data reveal differences in terrane thickness: a thin Yukon-Tanana terrane north of the Hines Creek fault and thicker Kahiltna/Wrangellia terranes to the south. Finally, the pattern of thin crust to the north and thicker crust to the south appears to be modified by late Cenozoic structures such as the Denali fault, with contractional thickening in the Alaska Range, including areas north of the Hines Creek fault in the northern foothills fold and thrust belt. BEAAR crustal thickness data suggest that major faults extend to the base of the crust.
    • Cubesat Attitude Control Utilizing Low-Power Magnetic Torquers & A Magnetometer

      Mentch, Donald B.; Thorsen, Denise (2011)
      The CubeSat Project has lowered development time and costs associated with university satellite missions that conform to their 10 centimeter cube design specification. Providing attitude control to a spacecraft, of such small volume, with a very limited power budget has been a challenge around the world. This work describes the development of an attitude control system based on a very low-power magnetic torquer used in conjunction with a magnetometer. This will be the first flight use of this torquer which is composed of a hard magnetic material wrapped inside of a solenoid. By discharging a capacitor through the solenoid, the magnetic dipole moment of this permanent magnet can be reversed. The completed attitude control system will make the first use of the low-power magnetic torquer to arrest satellite tip-off rates. It will then make the first known use of a dual axis magnetic dipole moment bias algorithm to achieve three-axis attitude alignment. The complete system is standalone for high inclination orbits, and will align the spacecraft to within 5 degrees of ram, nadir, and local vertical, without any requirement for attitude determination. The system arrests tip-off rates of up to 5� per second (in all 3 axes) for a satellite in a 600 kilometer polar orbit expending 0.56 milliwatts of power. Once in the proper alignment, it utilizes 0.028 milliwatts to maintain it. The system will function for low inclination orbits with the addition of a gravity boom. The system utilizes the magnetometer to calculate spacecraft body rates. This is the only known use of a magnetometer to directly measure spacecraft body rates without prior knowledge of spacecraft attitude.
    • Cultivating Sustainability Through Participatory Action Research: Place -Based Education And Community Food Systems In Interior Alaska

      Henry-Stone, Laura R.; Barnhardt, Ray; Gerlach, Craig; Kofinas, Gary; Webster, Joan Parker (2008)
      As the environmental movement grows into a broader sustainability revolution, we must move beyond the traditional scope of environmental education to address social-ecological challenges through integrated education for sustainability. This research explores how place-based education can promote sustainability of a community food system in which feedbacks between production and consumption are integrated within a biocultural region. Through participatory action research, the project develops and demonstrates pedagogical components of sustainability that are applicable to formal and non-formal educational contexts. In this pedagogy, the purpose of sustainability education is to foster a community culture that will promote the emergence of sustainability in complex adaptive systems with social and ecological components. This work is based at the Effie Kokrine Charter School (EKCS), a junior-senior high school in Fairbanks, Alaska that teaches with an Alaska Native approach, emphasizing place-based, experiential, and holistic education by utilizing students' natural and human communities to facilitate learning. The collaborative design of an Interior Alaska gardening curriculum serves as both an organizing framework for the project's fieldwork as well as an outcome of the research. The resultant gardening curriculum and the rationale behind its design demonstrate components of pedagogy for sustainability, including systems thinking, place-based and problem-based learning, eco-cultural literacy, eco-justice values, and appropriate assessment. Sustainability pedagogy within settings of higher education should also include action research. The structure of this dissertation research reflects how action research incorporates components of sustainability pedagogy. This pedagogical framework has theoretical and practical implications in multiple educational settings and indicates ways for our educational institutions to participate in the global sustainability revolution.
    • Culturability, Temporal Change, Phylogenetic Analysis, And Yield Of Bacterial Communities In A Subarctic Lake: Harding Lake

      Zhao, Xiaoming; Button, Don (2005)
      Heterotrophic bacteria, adapted to small concentrations of substrate, are a main component of the microbial flywheel. However, understandings of their activity, isolation, genetics, and nutrition are restricted to the large, easily isolated and culturable bacteria. By using the dilution culture method, apparent culturabilities could approach 10% in unamended lake water and were inversely proportional to the number of cells inoculated from mixed species in a natural environment from Harding Lake. Substrate additions could not improve bacterial culturability in the dilution cultures. Comparative sequence analyses of 16S rDNA genes showed that all bacterial species have similar lengths in the phylogenetic tree, suggesting similar evolution rates. These indicated close relationships among the six bacterial divisions: alpha-proteobacteria, beta-proteobacteria, gamma-proteobacteria, cytophaga/flexibacter/bacteriodes, acidobacteria, and cyanobacteria. Possible reasons include that metabolic enzymes of these bacteria were modified to adapt to low temperatures from tropical temperatures in arctic areas at the same time. These findings may provide insight into the recent evolution of the bacteria in near polar freshwater. Moreover, a high abundance of alpha-proteobacteria and gamma-proteobacteria was found in Harding Lake, suggesting high growth rates of these bacteria in the freshwater region. This is consistent with a rapid continuous shift in the distribution of dominant species observed in Harding Lake, according to the TRFLP, DGGE, and flow cytometry data. Our results also suggested that input of dissolved organic matter derived from terrestrial plants and soils, introduction of terrestrial bacteria, and bacteria themselves led to the bacterial species shifts associated with the seasonal change. Bacterial growth yield is used to measure this carbon conversion efficiency. However, bacterial growth yields have been seriously underestimated in previous studies. Our in situ values for bacterial growth yield from an amino acid mix were actually closer to 50% and 70% in active systems by using a modified, sensitive and accurate method and increased with the increase of temperature between 1�C and 6�C.
    • Cultural activity and market enterprise: a circumpolar comparison of reindeer herding communities at the end of the 20th century

      Koskey, Michael Stephen (2003-12)
      Reindeer herding throughout the circumpolar North is in decline. Investigating this decline, this dissertation takes a comparative approach with a focus on four case studies: the Chukchi of Chukotskii Peninsula, the Iñupiat of the Seward Peninsula, the Saami of the Kola Peninsula, and the Saami of Finnmark. Because various rates and types of decline are occurring in these different cases, a comparative method leads to a systematic analysis of how patterns develop in the practice of contemporary reindeer herding, both locally and globally. Comparing and contrasting the trajectories of declines in reindeer herding identifies and explains the dimensions of specific local-global processes, and situates them in wider contexts. These dimensions include economic incompatibilities, ecological stresses, and power inequities. By focusing on changes in reindeer herding over the last decade, this study reveals the effects of the incorporation of reindeer herding into the global economy, which is heavily dependent on existing infrastructure. This study also demonstrates the social position of reindeer herders and the cultural meaning of reindeer herding to the herders themselves. The willingness of regional and national governments to subsidize herding, and to ensure its survival through consistent access to pastures, is critically important to the success of reindeer herding as a productive agricultural enterprise. Furthermore, changing ecological factors potentially threaten reindeer herding as a subsistence activity. The consequences of decline, then, are explained through the identification of decline-inducing factors, such as ecological change, political vagaries, and the inappropriateness of reindeer herding as a capital-based enterprise under existing conditions of market and transportation infrastructural development.
    • Cultural and linguistic sensitivity in assessment tools: an adaptation of the drinkers inventory of consequences for Alaska Natives

      Cantil, Tony (2002-12)
      The purpose of this study was to determine the validity of a new assessment tool for Alaska Native clients with alcoholism. A sample of 23 Yup'ik clients at a regional treatment center were interviewed using the Drinker Inventory of Consequences for Alaska Natives (DrInC-AN), an adaption of the Drinker Inventory of Consequence (DrInC), the Alcohol Use Disorders Identification Test (AUDIT) and the Yup'ik Cultural Practices and Traditions (YCPT). These clients were selected, on a voluntary basis during the intake interview to the treatment center. Historically, assessment tools in alcoholism have not been culturally or linguistically sensitive to Alaska Native and Native American clientele. This study investigated the reliability and validity of the DrInC-AN in the assessment of severity of negative consequences of alcholol use among Alaska Natives.
    • Cultural Significance Of The 14(H) (1) Historic Sites Of Southeast Alaska

      Debaluz, Gail Marie; Wright, Miranda; Pullar, Gordon; Dayo, Dixie (2010)
      The study provides a literary review of first person accounts regarding section 14 (h) (1) of the Alaska Native Claims Settlement Act (ANCSA). This subsection is the legal mechanism for Alaska Native Corporations (ANC's) to obtain title to historic sites. Historic sites include villages, seasonal camps and cemeteries. The 14 (h) (1) collection is a nationally unique library and invaluable resource for tribal members to enhance the understanding of indigenous knowledge. It offers a profound appreciation of our ancestor's fortitude in challenging circumstances, instilling strength toward maintaining our identity as a dynamic, living, culture. The dissertation imparts the conceptual framework for tribal members to utilize the repository at their regional corporate office. The study seeks to understand Tlingit philosophy, inter-generational concepts, indigenous land stewardship, resource management, customary food practices, and cultural mores. It is complimented with an examination of local, state and national policy resulting from implementing ANCSA.
    • Culturally responsive teaching and student self-efficacy in Alaskan middle schools

      Christian, Scott; Kaden, Ute; John, Theresa; Sesko, Amanda; Ontooguk, Paul; Jester, Timothy (2017-12)
      Culturally responsive teaching may provide practices and dispositions which support closing the achievement gap between minority and Caucasian student populations. For this research, culturally responsive teaching can be considered as teaching practices that address students' specific cultural characteristics. These characteristics include common practices such as language, values and traditions but also include concepts such as communication, learning styles, and relationship norms. The research also presents a definition of culturally responsive teaching that extends beyond curriculum and instruction to focus on student teacher relationships, empathy, and the teacher as learner. This research explores the beliefs and practices around Culturally Responsive Teaching in ten Alaskan Middle Schools. A mixed-methods, sequential explanatory research design was used to answer the research questions: 1. How do teachers identify what is culturally responsive teaching, and what is not? 2. How is culturally responsive teaching implemented in Alaskan middle schools? 3. How is culturally responsive teaching connected to student self-efficacy in Alaskan middle schools? Although culturally responsive teaching has become a recognized practice in the fields of teacher preparation and professional development for teachers, the working definitions as well as evaluation tools are inadequate to describe the actual practice that teachers enact when they are engaged in culturally responsive teaching. Despite state regulations requiring Alaska school districts to include teaching practice of the Alaska Cultural Standards in teacher evaluations, there is only limited focused research available about the implementation of the standards in classrooms. Through semi-structured interviews and surveys with teachers and principals, formal classroom observations, as well as a student self-efficacy survey, this research addresses the lack of research and understanding regarding the relationship between culturally responsive teaching and self-efficacy for middle school students. This study identified the integration of local culture and language into academic content areas, teaching through culture, and the establishment of positive, respectful working relationships with students as promising practices for culturally responsive teaching.
    • Culturally-based primary prevention: an Alaskan native dance group

      Culp, Renée Irene (2005-08)
      This study investigated a culturally-based primary prevention program in Alaska. This program is a Native dance group that focuses on increasing the number of developmental assets within each member. Previous research has indicated that involvement in activities, such as the program described, may work to instill developmental assets, decreasing the likeliness of youths engaging in risk behaviors and increasing engagement in healthy behaviors. Findings from this study did not support the notion that youths who participate in a culturally-based primary prevention program demonstrate more assets of clinical significance than those youths who do not participate in such a program. Further, specific internal (self-esteem) and external (positive adult role models) developmental assets did not appear to result in benefits for those youths participating in this culturally-based primary prevention program. While it is evident that, within the scope of the present study, no apparent benefits for increasing developmental assets were found, this research highlights that the youths within this sample were remarkably high functioning. Considering these findings, it may be beneficial to first investigate factors that are contributing to the balance and wellness in the lives of these particular youths. Such factors may indeed encompass the essence of culturally-based primary prevention.
    • Culture And Empire: Rudyard Kipling's Indian Fiction

      Grekowicz, Eric John; Blalock, Susan (1996)
      A survey of Rudyard Kipling's Indian fiction indicates that his writings reflect a deeply-felt ambivalence toward the imperial projects of his contemporaries. Kipling condemns British characters who denigrate Indians or India, and in doing so, he subverts the Victorian notion of Britain's innate superiority. Kipling's early fiction reveals the author's respect for Eastern culture and religion. His India represents a utopic vision of cultural mixing. An anthropological perspective on these stories shows that the Indian fiction is designed to create cross-cultural communication. Kipling illustrates how failure to understand India ultimately destroys the British, and by attacking many of the injustices of imperialism, he fosters an atmosphere condusive to the synthesis of cultures. Kipling's ultimate enterprise is to promote tolerance of difference through understanding and respect of the other. <p>
    • Current Primary Production Rates Of The Western Arctic Ocean Estimated By Stable Carbon And Nitrogen Isotope Tracers

      Lee, Sang Heon; Whitledge, Terry E. (2005)
      Currently, the environments in the Arctic are rapidly changing. These changes of climate and ice conditions may alter the quantity, quality, and timing of production of ice algae and phytoplankton in the Arctic Ocean. The objectives in this study were to detect any change in the carbon production between current and previous studies and lay the groundwork for the future monitoring of ecosystem response to climate change in the different regions of the western Arctic Ocean. As an Arctic ocean mostly covered by multi or first-year ice, the deep Canada Basin had generally low photosynthetic rates and the maximum rates were found between 50 and 60 m in the basin. Based on the percentage of ice cover, the annual production ranged from 3 to 7.5 g C m-2 Z in the basin. Nutrients appear to be a main limiting factor at surface, whereas the phytoplankton activity might be limited by the low light in the Chl a-max layer. At the surface below the ice, photosynthetic activity might be controlled by both low light and nutrients. Studies of ice algae and phytoplankton at the first-year sea ice of Barrow in Alaska showed that bottom sea ice algae and phytoplankton are limited mainly by light. Therefore, the current downward trend of sea ice thickness and extent in Arctic Oceans might cause an increase in primary production or/and change in timing of the production. In addition, the composition in macromolecules of primary producers might be changed under the current ice conditions and thus nutritional status of higher trophic levels might be altered. As shallow shelf regions, Bering Strait/Chukchi Sea showed that the range of nitrate in the central Chukchi Sea was rather higher whereas the biomass of phytoplankton was lower in this study than in previous studies. Consistently, the mean carbon and nitrogen productivities from this study were almost half of values from previous studies. In conclusion, it appears that lower phytoplankton biomass in Bering Strait and the Chukchi Sea resulted in the lower carbon and nitrogen uptake rates and consequently more unused nitrate in the regions.
    • Current state of Alaska's glaciers and evolution of Black Rapids Glacier constrained by observations and modeling

      Kienholz, Christian; Hock, Regine; Arendt, Anthony; Bliss, Andrew; Braun, Matthias; Meyer, Franz; Truffer, Martin (2016-12)
      Glaciological studies rely on a wide range of input data, the most basic of which, accurate glacier extents, were not available on an Alaska wide scale prior to this work. We thus compiled a glacier database for Alaska and neighboring Canada using multi-sensor satellite data from 2000 to 2011. The inventory yielded a glacierized area of 86,720 km², which corresponds to ~12% of the global glacierized area outside the ice sheets. For each of the ~27,100 glaciers, we derived outlines and 51 variables, including centerline lengths, outline types, and debris cover, which provide key input for observational and modeling studies across Alaska. Expanding on this large-scale observational snapshot, we conducted two case studies on Black Rapids Glacier, Eastern Alaska Range, to assess its evolution during the late 20th and 21st centuries. Black Rapids Glacier, 250 km² in area, was chosen given its surge-type dynamics and proximity to critical infrastructure. Remotely sensed and in-situ elevation observations over the 1980--2001--2010 period indicated strong mass loss of Black Rapids Glacier (~0.5 m w.e. a⁻¹), with higher thinning rates over the 2001--2010 (~0.65 m w.e. a⁻¹) than the 1980--2001 period (~0.4 m w.e. a⁻¹). A coupled surface mass balance-glacier dynamics model, driven by reanalysis climate data, reproduced the glacier shrinkage. It identified the increasingly negative summer balances, a consequence of the warming atmosphere, as the main driver for the negative mass balance trend. Elevation observations in Black Rapids' surge reservoir suggested a surge was not imminent at the time of the analysis due to the lack of ice thickening. Re-initiation of sufficient elevation growth in the surge reservoir would require more favorable surface mass balances, as observed in the early 1980s. Compared to nearby Gulkana Glacier (a USGS benchmark glacier), the observed specific mass losses at Black Rapids Glacier were less pronounced, ~0.4 vs. 0.5 m w.e. a⁻¹ (1980--2001) and ~0.65 vs. 0.95 m w.e. a⁻¹ (2001--2010). The larger difference between the two glaciers' mass balances over the 2001--2010 period was partly caused by rockslide debris deposited on Black Rapids Glacier in 2002. This ~4.5 m thick debris layer, spread across 11.7 km² of Black Rapids lower ablation area, was modeled to suppress Black Rapids' glacier wide mass loss by ~20%. Modeling Black Rapids' evolution until 2100 suggested sustained glacier retreat, even under a repeated constant climate scenario, with ~225 km² of area remaining in 2100. Using a warming scenario (RCP 8.5), the modeled retreat was strongly accelerated with only ~50 km² of glacier area left in 2100. Given its thick, low-slope valley portion, Black Rapids Glacier is very susceptible to climate change. Its neighboring glaciers in the Eastern Alaska Range have similar properties, suggesting region wide glacier retreat in the future. To constrain this further, the Black Rapids case studies should be extended to the regional scale, a step now facilitated by the new Alaska wide glacier database.
    • The cyanide catalyzed dimerization of 2,3 naphthalenedicarboxaldehyde: a unique oxidative condensation product and derivatives

      McGill, Colin (2005-05)
      2,3 Naphthalenedicarboxaldehyde (NDA), in the presence of cyanide, is commonly used for the derivitization of amino acids and peptides to fluorescent 2-substituted 1-cyanobenzo[f]isoindoles, providing high sensitivity in capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) separations. CE studies of the neurotransmitters glutamate and aspartate have shown the formation of a number of competitive side products. Although mentioned in the literature, these side products have not been characterized. The product, 15-hydroxybenzo[g]benzo [6, 7]isochromeno[4,3-c]isochromen- 7(15H)-one (2), is reported here, as a dimerization of NDA in the presence of cyanide and atmospheric oxygen. The structure is confirmed by IR, LRFAB-MS, IRMS, and NMR spectra. Possible mechanisms for the formation of 2, its air oxidation, and an alternative benzoin condensation product are discussed. 15-hydroxybenzo[g]benzo [6,7]isochromeno[4,3-c]isochromen-7(15H)-one (2) is easily converted to full acetals via reflux in an alcohol solvent in the presence of an acid catalyst. Oxidation by NaOCI (aq) yields 3-(3-chloro-1,4-dioxo-3,4-dihydro-1H-benzo[g]isochromen-3-yl)-2-napthaldahyde (4) by capturing hypochlorite at the position æ the enolate. Oxidation by pyridinium chlorochromate (PCC) yields naptho[2,3-c]furan-1,3-dione (5) by multiple oxidations and the formation of the anhydride.
    • Cytogenetics and sex determination in collared lemmings

      Jarrell, Gordon Hamilton; Shields, Gerald F. (1989)
      Collared lemmings (Dicrostonyx groenlandicus rubricatus) from northeastern Alaska were found to have sex chromosomes that differ from those of their Siberian congeners, because of fusion to a particular pair of autosomes. But, as in Siberian lemmings, breeding experiments showed that sex determination involves an X-linked "male-repressor," which causes carriers to develop as fertile females, despite the presence of a Y chromosome. Genotypic frequencies in offspring are consistent with Mendelian expectations of such a system, hence natal sex ratios normally favor females. X-linkage of the male-repressor in Siberia and in Alaska indicates that the gene is probably located on the "original" arms of the X chromosome rather than on the fused autosomal arms, which differ on the two continents. One consequence of the autosomal fusion to the sex chromosomes is that deleterious recessive alleles on the autosome fused to the X chromosome are more resistant to selection than at truly autosomal loci. Another consequence is that, because males are heterozygous for loci fused to the sex chromosomes, they are more resistant to inbreeding depression than XX females. One inbred line produced a natal sex ratio of 67% males. The male-bias probably resulted from loss of the male-repressor and from a lethal carried on the formerly autosomal arm of the X chromosome. As inbreeding coefficients approached 0.3, the lethal would have been homozygous in half of the homogametic (female) zygotes. This phenomenon may explain the excess of males and XY females observed in earlier work. Also, if under the natural mating system, inbreeding depression limits fitness, then fusions of autosomal chromatin to the heterochromosomes could be an adaptation to reduce inbreeding depression in heterogametic individuals. Some other genetic features of collared lemmings do suggest endogamy. Female-biased sex ratios can evolve when mating occurs between neighboring individuals who are more related than if mating occurred randomly. Two proposed sources of such "viscous" gene flow in lemmings are cyclical changes in population density and mosaic habitat. Alternatively, could climate may favor winter aggregation and inhibit the dispersal of winter-born offspring, which would mature and mate with close relatives; dispersal and outbreeding would occur in summer. Thus, inbreeding would be seasonal rather than density-dependent and it is unnecessary to suppose discontinuous habitat.