• Near-roadway air pollution: evaluation of fine particulate matter (PM₂.₅) and ultrafine particulate matter (PM ₀.₁) in Interior Alaska

      Kadir, Abdul; Aggarwal, Srijan; Belz, Nathan; Barnes, David; Mao, Jingqiu (2019-05)
      Particulate air pollution in the form of fine (PM₂.₅) and ultrafine (PM₀.₁) particles has become a global concern, especially in urban areas with high population and vehicular traffic. Considerable research has been carried out to understand the underlying processes that impact particulate pollution, but most studies have been conducted in warmer and urban regions such as in California. The Fairbanks North Star Borough (FNSB), in Interior Alaska, provides an interesting example of a relatively small- to mid-sized northern locality (population ~100,000) with persistent air quality issues and extremely cold climatic conditions for a major part of the year. Since December 2009, the FNSB has been designated a nonattainment region by the U.S. Environmental Protection Agency for the federal PM₂.₅ standard. As part of their remediation efforts, the borough and state have undertaken increased monitoring by using an on-roadway monitoring vehicle (sniffer vehicle) and stationary near-roadway sites for air quality measurements, beyond what is required for regulatory compliance. One of the goals of this project was to develop a novel data investigation and analyses methodology for the geospatial air quality data collected by the borough's mobile monitoring vehicle (years 2012-15), to shed light on the PM₂.₅ issues faced by the FNSB. In addition, this research also undertook measurements of ultrafine particle (UFP) concentration levels at four road weather information system (RWIS) sites in the FNSB region. UFPs, though unregulated, are considered to have significant human health impacts and no known studies have investigated UFPs in FNSB. In addition to UFPs, other parameters such as PM₂.₅, traffic, and weather data were measured at the same locations to investigate any underlying trends/correlations with UFPs. In the first part of the research with mobile monitoring, data were categorized in nine different groups based on their mean and standard deviation values to determine the spatiotemporal distribution of PM₂.₅. This novel way of grouping data allows identification of locations with consistently poor and consistently better air quality, by going beyond the simple analyses of means and accounting for variability and standard deviation in the data. In addition to hotspot identification, analyses found that average on-roadway PM₂.₅ concentrations were higher in North Pole (27.2 μg/m³) than in Fairbanks (12.9 μg/m³), and that average concentrations were higher in the background stationary monitoring data (29.4 μg/m³) than in the mobile monitoring data (20.0 μg/m³) for the study period. Not surprisingly, significant negative correlations (R² = 0.49 for Fairbanks, and R² = 0.31 for North Pole) were found between temperature and PM₂.₅. Temporal distribution of the data suggests that PM₂.₅ levels increase gradually in the months of October and November, peak during the months of December, January, and February, and quickly plummet beginning March. In the latter part of the study, data on UFP measurements were collected at four RWIS sites in the FNSB for four days between March 1 and 18, 2017, for five continuous hours each day. Among other parameters, PM₂.₅ concentrations, temperature, relative humidity, wind speed, and traffic volume data were collected. Data were analyzed to develop correlations between UFPs and other parameters, to compare data from this study with other studies, and to determine current roadside UFP concentration levels in interior Alaska. Fairbanks roadside locations showed higher mean UFP counts (41,700 particles/cm³) than the North Pole (22,100 particles/cm³) locations. Similarly, for the period of study, Fairbanks roadside locations showed higher PM₂.₅ concentrations and traffic counts (6.3 μg/m³; 15 vehicles/min) than the North Pole (4.6 μg/m³; 10 vehicles/min) locations, both being well below the on-roadway and background PM₂.₅ concentrations estimated in the first part of this report. Multilinear predictive models were developed for estimation of UFPs and PM₂.₅ based on weather and traffic parameters. This first study of UFPs in Alaska improves our understanding of near-roadway UFPs in cold regions.
    • Negotiating the languages of landscape: place naming and language shift in an Inupiaq community

      Marino, Elizabeth K. (2005-12)
      This thesis examines the correlations between language shift, language death, and cultural change through the use of place names in White Mountain, Alaska. Traditionally Inupiaq place names have served as descriptive tools for navigating the landscape and as memory markers for oral histories, taboos, and places of harvest. Local Inupiaq place names have been inscribed in social memory for generations and, according to Inupiaq elders in White Mountain, none are without significance. As English replaces the Inupiaq language, these traditional place names fall out of use, as well as the local histories and other information associated with them. English place names used today continue to inscribe information into the land, but of a different sort. This thesis finds that cultural change and cultural resiliency can be clearly observed through and are related to language shift in White Mountain. Included in this thesis are listings and maps of traditional Inupiaq place names from White Mountain, Alaska.
    • Neotectonic framework of the north-central Alaska Range foothills

      Bemis, Sean Patrick (2004-12)
      The northern foothills of the Alaska Range form a northward-convex salient at the apex of this orogen and the Denali fault. Despite the proximity of the northern foothills to the Denali fault and several historic large-magnitude earthquakes, the tectonic framework of this region has not been well-studied. A distinct pattern of east-trending folds and faults exists in both the bedrock and the geomorphic features. To assess the active structures of the region, I interpreted previous geologic mapping, developed cross-sections across the foothills belt, analyzed topographic and stream profiles, mapped the sequence of Quaternary fluvial terraces, and performed GPS transects across several terrace treads. A northward topographic slope across the northern foothills corresponding with the pattern of faulting and folding suggests the presence of an orogenic wedge overlying a south-dipping basal detachment. Mapping and GPS transects show evidence for progressive deformation of the terraces. Geomorphic analyses suggest deformation and differential uplift over the entire foothills belt. These results indicate that the northern foothills are an active fold-and-thrust belt and are prograding northward into the Tanana Basin. Tectonic activity of these structures suggests that this region represents a potential seismic hazard for nearby military facilities and important transportation corridors.
    • The neotectonics, uplift, and accommodation of deformation of the Talkeetna mountains, south-central Alaska

      Mixon, Demi C.; Hanks, Catherine; Nadin, Elisabeth; Beget, James (2016-08)
      South-central Alaska is home to many tectonic structures and mountain ranges that have experienced active uplift and deformation within the past 5 to 10 Ma. The Talkeetna Mountains are located above the area of flat-slab subduction of the Yakutat microplate. I hypothesize that the Talkeetna Mountains have been uplifted as a result of this underlying flat-slab subduction and that areas of the Talkeetna Mountains are neotectonically active. The Talkeetna Mountains are deforming heterogeneously across four different structural domains defined by differences in geomorphic patterns, seismicity, dominant fault types, and the orientation of horizontal maximum stress (SHmax). A strain partitioning structure divides the northern and southern domains, and is observed by a change in SHmax orientation from E-W in southern domains to NW-SE in the northern domain. The strain partition is accommodated by a crustal break along the Talkeetna thrust fault, which is expressed at the surface as a wide zone of deformation. Apatite fission-track analysis suggests two distinct periods of uplift: one dated from 45 to 30 Ma and another from approximately 10 Ma to present, with uplift rates of 0.14 mm/yr and 0.24 mm/yr, respectively. The first phase of uplift coincides with a time of significant plate reorganization in the north Pacific which resulted in translation of terranes northwestward. The second phase of uplift correlates with Neogene accretion of the Yakutat microplate. I propose that the majority of Neogene deformation and uplift in the Talkeetna Mountains is due to farfield deformation in the upper plate above the subducting slab. Variations in both composition of the crust and depth to the downgoing slab resulted in strain partitioning and northwest-directed compression in the northern Talkeetna Mountains and northwest compression and warping in the southern Talkeetna Mountains.
    • Nest -Building Behavior In House Mice (Mus Musculus), A Potential Model Of Obsessive -Compulsive Disorder In Humans

      Greene-Schloesser, Dana M.; Bult-Ito, Abel (2007)
      OCD (obsessive-compulsive disorder) is a chronic and debilitating psychiatric condition characterized by intrusive and persistent thoughts (obsessions) and repetitive behaviors (compulsions) that become ritualistic in an attempt to escape the obsessions. Currently there is a paucity of animal models with robust and spontaneous (non-drug or non-behaviorally induced) compulsive-like behaviors. This study is aimed at validating a novel robust and spontaneous genetic mouse model of OCD. The compulsive-like nest-building behavior in mice selected for high levels of nest-building behavior (BIG) has good face validity, with a behavioral phenotype that resembles hoarding behavior characteristic of OCD. In addition, male and female BIG mice displayed compulsivelike digging behavior relative to mice selected for low levels of nest-building behavior (SMALL), as assessed by the marble-burying test. Both chronic oral fluoxetine and clomipramine treatment reduced compulsive-like nest-building behavior in male BIG mice. Furthermore, chronic oral fluoxetine administration decreased nest-building behavior of BIG mice in a dose-dependent manner, while desipramine, an antidepressant not effective for treating OCD, did not significantly alter this behavior. The administration of fluoxetine did not cause a decrease in general locomotor behavior. These findings suggest that the nest-building phenotype has predictive validity. In addition, chronic oral fluoxetine treatment reduced compulsive-like digging behavior in male and female BIG mice as compared to SMALL mice. Gender effects were also found in treatment response. Clomipramine did not reduce nest-building in female BIG mice in a dose-dependent manner, which is consistent with previous studies. These data are in contrast to previous studies using BIG male mice which had a significant decrease in nest-building behavior with oral clomipramine. These results are consistent with studies on humans, which have found gender differences in the treatment effects of antidepressants. Additional construct validity is implicated by the results of targeted serotonergic lesions of the raphe nuclei in male BIG mice, which reduced repetitive nest-building behavior. More research is necessary to confirm the appropriateness of this model for human OCD; however, this model is promising based on the data that support good face, predictive and construct validity.
    • Nest and duckling survival of scaup at Minto Flats, Alaska

      Walker, Johann (2004-05)
      To address the hypothesis that declines in recruitment were related to recent declines in abundance of lesser and greater scaup, I estimated variation in nest and duckling survival of these species at Minto Flats, Alaska (64°50'N, 148°50'W) during 2002-2003. I included nest survival data from two previous studies conducted during 1989-1993 in my analysis. Daily Survival Rate (DSR) of nests was variable within and among years and among habitats. Estimated nest survival of scaup ranged from 0.02 (95% CI: 0.00 to 0.06) in 1992 to 0.61 (95% CI: 0.50 to 0.74) in 1993. Predation was the primary apparent cause of nest failure, and flooding of nests was an important secondary influence. DSR of ducklings varied between years and increased with age of the ducklings and body condition of the brood female. Duckling survival to 30 days was: 0.24 (95% CI: 0.16 to 0.36) in 2002 and 0.03 (95% CI: 0.00 to 0.19) in 2003. I conclude that high temporal variability in production of scaup at Minto Flats was likely related to annual variation in the risks of predation and flooding and indicated that intermittent years of high production could be particularly influential to this population.
    • Nesting biology of the spectacled eider Somatera fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska

      Dau, Christian P. (1974-05)
      Nesting biology of the Spectacled Eider Somateria fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska, was studied in 1972 and 1973. These data are compared with data from 1969, 1970, and 1971 (Eisenhauer et al. 1971, Eisenhauer and Frazer 1972, and Mickelson 1973). Paired, the birds arrived mostly from the north within a 3-4 day period in mid-May. Before 7 June, 80 percent of the nests were initiated. Located on islands, shorelines and peninsulas, most nests were within 7 feet of water. Rate of egg laying was 1/day (mean clutch size 4.5 eggs). Incubation lasted 24 days. Hatching took place from 20 June to 10 July (nesting success range 35 percent to 83 percent). Timing of nest site availability appears to dictate clutch size and reproductive success. Ducklings are raised on shallow freshwater ponds within 1.5 miles of their nest site.
    • Nesting ecology of ducks in interior Alaska

      Petrula, Michael J. (1994-09)
      This study represents one of the first intensive efforts to locate and monitor duck nests in interior Alaska. We located 263, 409 and 450 nests of 12 duck species on Minto Flats in 1989, 1990 and 1991,respectively. We conclude that habitat for breeding waterfowl cannot be considered stable in interior Alaska. Flooding reduced the availability of meadows which precluded ducks from nesting in high-water years despite their presence during the Breeding Pair Survey. Differences in the length of the breeding season and differential response to photoperiod between sub-Arctic and prairie nesting ducks suggest the potential for genetic differences between populations. Similar clutch sizes between high and mid-latitudes, however, suggest that ducks are able to compensate for the additional energetic costs associated with breeding at high latitudes. Flooding of meadow habitat and low nest success resulting from predation probably limit overall duck production on Minto Flats.
    • Nesting ecology of migratory golden eagles (Aquila chrysaetos) in Denali National Park, Alaska

      McIntyre, Carol L. (1995-12)
      Between 1988 and 1993 I measured occupancy of nesting territories and reproduction of golden eagles (Aquila chrysaetos) in Denali National Park, Alaska. I collected data occupancy of nesting territories and three reproductive variables (pairs nesting, pairs producing fledglings, and fledgling production) at 74 nesting territories using three aerial surveys each year. During my study, annual fledgling production varied nearly threefold, from 20 fledglings in 1992 to 58 fledglings in 1989. Although rates of nesting territory occupancy did not vary significantly among years (yj = 8.21, d.f. = 5, P = 0.114), I noted significant variation in the proportion of pairs laying eggs (X2 = 33.12, d.f. = 5, P < 0.001) and the proportion of pairs fledging young (X2 = 16.03, d.f. = 5, P = 0.007) among years. Decreases in pairs laying eggs were correlated with decreases in average daily numbers of snowshoe hare (Lepus americanus) and willow ptarmigan (Lagopus lagopus) observed in the study area (rs = 0.83, P = 0.04).
    • Networks of change: extending Alaska-based communication networks to meet the challenges of the anthropocene

      Hum, Richard E.; Taylor, Karen; Chapin, F. Stuart, III; Koskey, Michael; Brower, Pearl Kiyawn Nageak; Carlson, Cameron (2017-08)
      The Anthropocene is a contested term. As I conceptualize it throughout this dissertation, the Anthropocene is defined by an increased coupling of social and environmental systems at the global scale such that the by-products of human processes dominate the global stratigraphic record. Additionally, I connect the term to a worldview that sees this increased coupling as an existential threat to humanity's ability to sustain life on the planet. Awareness that the planet-wide scale of this coupling is fundamentally a new element in earth history is implicit in both understandings. How individuals and communities are impacted by this change varies greatly depending on a host of locally specific cross-scale factors. The range of scales (physical and social) that must be negotiated to manage these impacts places novel demands on the communication networks that shape human agency. Concern for how these demands are being met, and whose interests are being served in doing so, are the primary motivation for my research. My work is grounded in the communication-oriented theoretical traditions of media ecology and the more recent social-ecological system conceptualizations promoted in the study of resilience. I combine these ideas through a mixed methodology of digital ethnography and social network analysis to explore the communication dynamics of four Alaska-based social-ecological systems. The first two examples capture communication networks that formed in response to singular, rapid change environmental events (a coastal storm and river flood). The latter two map communication networks that have formed in response to more diffuse, slower acting environmental changes (a regional webinar series and an international arctic change conference). In each example, individuals or organizations enter and exit the mapped network(s) as they engage in the issue and specific communication channel being observed. Under these parameters a cyclic pattern of network expansion and contraction is identified. Expansion events are heavily influenced by established relationships retained during previous contraction periods. Many organizational outreach efforts are focused on triggering and participating in expansion events, however my observations highlight the role of legacy networks in system change. I suggest that for organizations interested in fostering sustainable socialecological relationships in the Anthropocene, strategic intervention may best be accomplished through careful consideration of how communicative relationships are maintained immediately following and in between expansion events. In the final sections of my dissertation I present a process template to support organizations interested in doing so. I include a complete set of learning activities to facilitate organizational use as well as examples of how the Alaska Native Knowledge Network is currently applying the process to meet their unique organizational needs.
    • Neural control of singing in the dark-eyed junco (Junco hyemalis)

      Gulledge, Cynthia Corbitt (1997)
      This dissertation includes several discrete projects addressing various aspects of the neural control of singing in the Dark-eyed Junco (Junco hyemalis), a migratory songbird. I collected the birds from a local wild population during the breeding season and migration. Chapter 2 addresses the role of testosterone in controlling volumes of the brain regions that control song learning and song production (vocal control regions, VCRs), which grow and shrink seasonally and are correlated with changes in singing behavior. I found that: the role testosterone plays may depend on the age of the bird and the brain region in question. Expanding on that study, I investigated the independent roles of testosterone and photoperiod in the control of VCR volumes in adolescent male juncos (Chapter 3). In seasonally breeding species, circulating androgens increase with increasing photoperiod, so increases in VCR volumes in the spring had been thought to be a result of photoperiod-induced increases in testosterone. Experimental separation of photoperiod and testosterone revealed that long photoperiod alone can have stimulatory effects on VCR growth, despite low testosterone levels. In fact, in adolescent male juncos, lengthening photoperiod may play a greater role in determining VCR volumes than testosterone does, again suggesting that the role of testosterone in the vocal control system may change with age. Other neurochemicals besides testosterone are present in the vocal control system; Chapter 4 describes the first description of opioid peptide receptor localization and density measurement in the vocal control system of adult male songbirds. I expanded that study to include nonsinging female and juvenile juncos (Chapter 5). The results of the expanded study indicate that opioids may modulate development of the vocal control system between adolescence and adulthood, as well as auditory processing throughout life.
    • Neural Network Approach To Classification Of Infrasound Signals

      Lee, Dong-Chang; Szuberla, Curt (2010)
      As part of the International Monitoring Systems of the Preparatory Commissions for the Comprehensive Nuclear Test-Ban Treaty Organization, the Infrasound Group at the University of Alaska Fairbanks maintains and operates two infrasound stations to monitor global nuclear activity. In addition, the group specializes in detecting and classifying the man-made and naturally produced signals recorded at both stations by computing various characterization parameters (e.g. mean of the cross correlation maxima, trace velocity, direction of arrival, and planarity values) using the in-house developed weighted least-squares algorithm. Classifying commonly observed low-frequency (0.015--0.1 Hz) signals at out stations, namely mountain associated waves and high trace-velocity signals, using traditional approach (e.g. analysis of power spectral density) presents a problem. Such signals can be separated statistically by setting a window to the trace-velocity estimate for each signal types, and the feasibility of such technique is demonstrated by displaying and comparing various summary plots (e.g. universal, seasonal and azimuthal variations) produced by analyzing infrasound data (2004--2007) from the Fairbanks and Antarctic arrays. Such plots with the availability of magnetic activity information (from the College International Geophysical Observatory located at Fairbanks, Alaska) leads to possible physical sources of the two signal types. Throughout this thesis a newly developed robust algorithm (sum of squares of variance ratios) with improved detection quality (under low signal to noise ratios) over two well-known detection algorithms (mean of the cross correlation maxima and Fisher Statistics) are investigated for its efficacy as a new detector. A neural network is examined for its ability to automatically classify the two signals described above against clutter (spurious signals with common characteristics). Four identical perceptron networks are trained and validated (with >92% classification rates) using eight independent datasets; each dataset consists of three-element (each element being a characterization parameter) feature vectors. The validated networks are tested against an expert, Prof. Charles R. Wilson, who has been studying those signals for decades. From the graphical comparisons, we conclude that such networks are excellent candidate for substituting the expert. Advantages to such networks include robustness and resistance to errors and the bias of a human operator.
    • Neural-Network Modeling Of Placer Ore Grade Spatial Variability

      Ke, Jinchuan; Bandopadhyay, Sukumar (2002)
      Traditional geostatistical methods have been used in ore reserve estimation for decades. Research in the last two decades or so has added a number of other statistical methodologies for ore reserve estimation procedures. Recent advances in neural networks have provided a new approach to solve this problem. This thesis is focused on the Neural-network modeling for the estimation of placer ore reserve. Due to the spatial variability, multiple dimensional inputs and very noisy drill hole sample data from the selected region, it requires that the neural-network be organized in a multiple-layers to handle the non-linearity and hidden slabs for smoothing the predicted results. Various neural-network architectures are investigated and the Back-propagation is selected for modeling the ore reserve estimation problem. Sensitivity analysis is performed for the following parameters: the type of neural-network architecture, number of hidden layers and hidden neurons, type of activation functions, learning rate and momentum factors, input pattern schedule, weight updated, and so on. The influences of these parameters on the predicted output are analyzed in details and the optimal parameters are determined. To investigate the accuracy and promise of neural network modeling as a tool for ore reserve estimation, the ore grade and tonnage of Neural-network output is compared with those estimated by geostatistical methods under various cut-off grades. In addition, the overall performance is also validated by the analysis of R-squared (R2), Root-Mean-Squared (RMS), and the comparison between predicted values and 'actual' values. As the final part of this study, the optimized Neural Network was used to estimate the distribution of placer gold grade and volume of gold resource in offshore Nome. The predicted results for all the mining blocks in the lease area are validated by checking the values of RMS, R2, and Scatter plots. The estimated gold grades are also presented as contour maps for visualization.
    • Neuroendocrine control of song in the dark-eyed junco (Junco hyemalis)

      Dloniak, Stephanie Marie (2000-08)
      This dissertation includes three discrete projects addressing various aspects of the neuroendocrine control of song in the Dark-eyed Junco (Junco hyemalis), a migratory songbird. Specifically, the roles of testosterone, photoperiodic condition, opioids, and age were investigated with respect to song production and neural plasticity in the regions of the brain that control song (vocal control regions, VCRs)." The author "found that, in males photoperiodic condition and testosterone interact to regulate seasonal VCR volume plasticity, whereas testosterone alone controls song production. The opioid system is probably not involved in VCR plasticity or song production, but is indicated to play a role in song learning or auditory processing. Finally, VCR volumes and song production do not differ with age in photostimulated adult male juncos.
    • Neuroplasticity And Neurotoxicology: Central Breathing Control Following Developmental Nicotine Or Ethanol Exposure

      Brundage, Cord M.; Taylor, Barbara (2010)
      Nicotine or ethanol exposure early in development are both risk factors for Sudden Infant Death Syndrome (SIDS). I tested the hypothesis that both nicotine and ethanol may be linked to SIDS by impairing central breathing control responses to low oxygen (hypoxia) and high carbon dioxide (hypercapnia) stressors. Experiments were conducted in bullfrog tadpoles, a model system for respiratory neurotoxicology research. I addressed three specific aims: to characterize the effect of chronic ethanol on central responses to hypercapnia and hypoxia, to characterize the effect of chronic nicotine on central hypoxic responses, and to determine the persistence of hypercapnic impairments following 10-wk exposure to either nicotine or ethanol. 10-wk nicotine exposure resulted in neuroplastic changes that eliminated the central hypoxic responses of early but not late metamorphic tadpoles. Thus, central responses to both hypoxia and hypercapnia were impaired following nicotine exposure. The attenuated central hypercapnic response of nicotine-exposed tadpoles persisted for 1 - 3 wk. Following 10-wk chronic ethanol exposure central responses to hypercapnia and hypoxia were lost regardless of the developmental timing of exposure. Impairments in central hypercapnic responses persisted for 3 - 6 wk after ethanol exposure ended. The recovery of central hypercapnic responses in nicotine- and ethanol-exposed tadpoles may be an example of recuperative neuroplasticity resulting in either a reinstatement of network components and functions or an accommodation to deleterious nicotine- and ethanol-evoked neuroplastic changes. Collectively these data suggest that both nicotine and ethanol may target adaptive and compensatory mechanisms in central breathing control. The teratogen-induced impairments were developmentally dependent in the case of nicotine, and they persisted longer following ethanol exposure. The overall result of exposure to either neuroteratogen was an inability to respond to central breathing stressors, supporting the possible link to SIDS.
    • Neuroprotection in hippocampal slices from the hibernating species Arctic ground squirrel, Spermophilus parryii

      Ross, Austin Pfeiffer (2005-08)
      Stroke is the third leading cause of death in the U.S. and the leading cause of adult onset disability worldwide. Despite tremendous efforts to find therapeutics, only one currently approved treatment for stroke exists which is indicated for use in less than 5% of stroke victims. During a stroke, the brain experiences oxygen and nutrient deprivation due to lack of blood flow (i.e., ischemia) and tissue destruction ensues. Hibernating Arctic ground squirrels (AGS), Spermophilus parryii, are able to survive profound decreases in blood flow and cerebral perfusion during torpor, and return of blood flow (i.e., reperfusion) during intermittent euthermic periods without neurological damage. Hibernating species are a natural model of tolerance to insults, such as ischemia, that would be injurious to non-hibernating species, and are a novel model for investigating much needed therapeutics for pathologies such as stroke. Tolerance to traumatic brain injury demonstrated in hibernating AGS in vivo could be due to tissue properties, circulating factors or hypothermia. To investigate mechanisms of tolerance in brain of hibernating animals, the current project established a chronic culture system for hippocampal slices from AGS at 37°C. By using this in vitro approach, tissue properties of AGS brain could be assessed without effects of circulating factors or the protective nature of hypothermia. This project determined whether an intrinsic tissue tolerance to oxygen and nutrient deprivation, an in vitro model of ischemia-reperfusion, persists in chronic AGS slice culture and addressed associated mechanisms. Here, for the first time, slices from hibernating AGS were shown to possess a persistent tolerance to oxygen and nutrient deprivation. Thus, intrinsic tissue properties in hippocampus of hibernating AGS confer tolerance to oxygen and nutrient deprivation in addition to hypothermia. Evidence in the literature supports that neuroprotective factors are present in serum and tissue of hibernating animals, and here a preliminary investigation suggests that factors in AGS serum may play a role in protection in brain of hibernating AGS. Finally, a model is proposed that incorporates these findings, which suggests that mimicking properties of tissue and serum from hibernating animals in non-hibernating species may yield success in developing efficacious stroke therapeutics.
    • Neuroprotection in the hibernating brain: tissue trauma and glutamate studied by microdialysis

      Zhou, Fang (2001-08)
      Hibernation, a natural model of tolerance to 'cerebral ischemia', represents a state of pronounced fluctuation in cerebral blood flow where no brain damage occurs. This study systematically investigates the brain tissue response of hibernating and euthermic arctic ground squirrels to CNS trauma, modeled by insertion of microdialysis probes. The effect of glutamate, an excitatory amino acid neurotransmitter, on the cellular response and the origin of the significant amount of gltuamate were determined by quantitative microdialysis study. The present results indicate in euthermic brain tissue a typical inflammatory tissue response evidenced by the presence of activated microglia and astrocytes and the oxidative stress response. However, this response was profoundly suppressed in hibernating animals. Importantly, the progressive increase in [glu]dia is not necessarily associated with the enhanced tissue response observed in euthermic animals and could be avoided by using sterile microdialysis technique, which suggests a microbial origin of glutamate.
    • New 3-d video methods reveal novel territorial drift-feeding behaviors that help explain environmental correlates of Chena River chinook salmon productivity

      Neuswanger, Jason; Rosenberger, Amanda E.; Evenson, Matthew J.; Adkinson, Milo D.; Bradford, Michael J. (2014-08)
      Chinook salmon (Oncorhynchus tshawytscha) are critical to subsistence and commerce in the Yukon River basin, but several recent years of low abundance have forced devastating fishery closures and raised urgent questions about causes of the decline. The Chena River subpopulation in interior Alaska has experienced a decline similar to that of the broader population. To evaluate possible factors affecting Chena River Chinook salmon productivity, I analyzed both population data and the behavior of individual fish during the summer they spend as fry drift feeding in the river. Using a stereo pair of high definition video cameras, I recorded the fine-scale behavior of schools of juvenile Chinook salmon associated with woody debris along the margins of the Chena River. I developed a software program called VidSync that recorded 3-D measurements with sub-millimeter accuracy and provided a streamlined workflow for the measurement of several thousand 3-D points of behavioral data (Chapter 1). Juvenile Chinook salmon spent 91% of their foraging attempts investigating and rejecting debris rather than capturing prey, which affects their energy intake rate and makes foraging attempt rate an unreliable indicator of foraging success (Chapter 2). Even though Chinook salmon were schooling, some were highly territorial within their 3-D school configurations, and many others maintained exclusive space-use behaviors consistent with the population regulatory effects of territoriality observed in other salmonids (Chapter 3). Finally, a twenty-year population time series from the Chena River and neighboring Salcha River contained evidence for negative density dependence and a strong negative effect of sustained high summer stream discharge on productivity (Chapter 4). The observed territoriality may explain the population's density dependence, and the effect of debris on foraging efficiency represents one of many potential mechanisms behind the negative effect of high stream discharge. In combination, these findings contribute to a statistically and mechanistically plausible explanation for the recent decline in Chena River Chinook salmon. If they are, in fact, major causes of the decline (other causes cannot be ruled out), then we can be tentatively hopeful that the population may be experiencing a natural lull in abundance from which a recovery is possible.