• Validating a GPS collar-based method to estimate parturition events and calving locations for two barren-ground caribou herds

      Hepler, Joelle D.; Griffith, Brad; Falke, Jeff; Roach, Jen (2019-12)
      In remote landscapes, it is difficult and expensive to document animal behaviors such as location and timing of parturition. When aerial surveys cannot be conducted as a result of weather, personnel or fiscal constraints, analyses of GPS collar movement data may provide an alternate way to estimate parturition rates and calving ground locations. I validated two methods (population-based method and individual-based method), developed to detect calving events of sedentary woodland caribou, on multiple years of data for two different migratory barren-ground caribou herds in Alaska, the Porcupine and Fortymile herds. I compared model estimates of population parturition rates, individual calving events, calving locations and calving dates to estimates from aerial survey data for both herds. For the Porcupine herd we also compared model estimates of annual calving ground sizes and locations of concentrated calving area centroids to those found with aerial survey. More years of data would be required for additional statistical power but for both the Porcupine and Fortymile herds, we found no significant difference between the population-based and individual-based method in: 1) individual classification rate accuracy (0.85 vs. 0.88, respectively; t = -7, P = 0.09, df = 1 and 0.85 vs. 0.83, respectively; t = 0.46, P = 0.69, df = 2) or 2) annual average distance from aerial survey calving locations (8.9 vs. 7.8 km, respectively; t = 0.16, P = 0.90, and 5.2 vs. 3.7 km, respectively; t = 1.03, P = 0.20). Median date of calving was estimated within 0-3 days of that estimated by aerial survey for both methods. Population parturition rate estimates from aerial survey, the population-based and individual-based methods were not significantly different for the PCH or FCH (0.91, 0.88 and 0.95, respectively; F = 0.67, P = 0.60, df = 2, and 0.83, 0.83 and 0.96, respectively; F = 3.85, P = 0.12, df = 2). Ultimately, more years of data would be required to support or reject the lack of significant differences between methods that we observed.
    • Validation and application of infrared thermography for the assessment of body condition in pinnipeds

      Nienaber, Jeanette (2009-08)
      Infrared thermography (IRT) was used to collect baseline information on skin surface temperatures of two species of pinnipeds, the harbor seal (Phoca vitulina; n = 6) and the Steller sea lion (Eumetopias jubatus; n = 2). The IRT technique was validated against objects of known temperature and through post-collection software manipulation of environmental parameters that influence IRT output (emissivity, distance, relative humidity, ambient temperature and reflected temperature). From February 2007 to February 2008, biweekly measurements were taken of skin surface temperature (FLIR P25 infrared camera) with subsequent measurements of blubber depth (SonoSite Vet 180 portable imaging ultrasound system) on captive individuals at the Alaska SeaLife Center, Seward, Alaska. Once validated, skin surface temperatures in 10 defined regions (whole body, torso, head, eye, muzzle, shoulder, axillae, hip, fore and hind flipper) were used to determine seasonal variability as well as consistent hot or cold spots, and of those spots, which may act as thermal windows (defined areas of active heat loss and/or retention). Concurrent measurements of blubber depth were compared to skin surface temperatures at eight body sites to assess: a) the impact of insulation level on skin surface temperature on a site-specific scale, and b) the potential use of IRT as an alternative method for the non-invasive measurement of body condition. Both species varied seasonally in skin surface temperature from winter to reproductive and molt to winter, however, harbor seals had greater regional variation. Similar hot and cold spots were consistently recognized in both species with shoulder, axillae, fore and hind flipper identified as likely thermal windows. While some site-specific significant relationships were found between skin surface temperature and blubber thickness, insulation level alone explained a very small portion of the variance. Future studies to determine the factors influencing the variance on skin surface temperature (i.e., blood flow to the skin) warrant further exploration.
    • A validity study of the reasons for life scale with emerging adult college students

      Curns, Daniel B.; Gonzalez, Vivian M.; Swift, Joshua K.; Skewes, Monica C.; Ashdown, Brien K. (2014-12)
      This study examined the validity of the Reasons for Life Scale (RFLS) with emerging adult college students. The RFLS measures "reasons for life." It was developed for use with Alaska Native youth as a way to assess potential risk of suicide without directly questioning about suicidal ideation or history of suicide attempts. This study sought to adapt the RFLS for use with emerging adult (age 18-25) college students, and to examine its factor structure and convergent validity with this population. First, a focus group was conducted to assist in rewording two Alaska Native-specific items from the RFLS for non-Natives. Then, with the additional items from the focus group, the revised version of the RFLS (RFLS-R) and other suicide-related measures were administered to a sample of 116 emerging adult college students. Exploratory factor analysis indicated a unidimensional factor structure for the RFLS-R with this sample. The RFLS-R showed a significant and strong correlation with the Reasons for Living Inventory (RLI; r = .70), which, like the RFLS-R, measures reasons for living but makes direct reference to suicide. There also were significant moderate negative correlations with the Suicidal Behavior Questionnaire - Revised (SBQ-R; r = -.36) and the Adult Suicidal Ideation Questionnaire (ASIQ; r = -.29). There was a significant moderate correlation between the RFLSR and a measure of socially desirable responding, the Balanced Inventory of Desirable Responding (BIDR; r = .31), with similar correlations found between the BIDR and other suicide-related measures included in this study. The results suggest that socially desirable responding did not strongly affect participants' responding or explain the associations found among the measures. The high correlation with the RLI suggests that the RFLS-R measures a similar construct, providing evidence of convergent validity; however, the RLI was more highly correlated with measures of suicidality than the RFLS-R -- suggesting that while the RFLS was moderately associated with measures of suicidality, it is a weaker predictor of suicide risk than the RLI. Although the RFLS-R was not as highly correlated with measures of suicidality as the RLI, which directly mentions suicide, the RFLS-R is the only known suicide measure that completely avoids items and instructions that mention suicide, therefore it may be useful in contexts where directly discussing suicide is not acceptable or appropriate.
    • Valuing residential energy efficiency in two Alaska real estate markets: a hedonic approach

      Pride, Dominique J.; Little, Joseph; Baek, Jungho; Lovecraft, Amy Lauren; Mueller-Stoffels, Marc (2017-05)
      Alaska households have high home energy consumption and expenditures. Improving the energy efficiency of the housing stock can reduce home energy consumption, thereby reducing home energy expenditures and CO₂ emissions. Improving the energy efficiency of a home may also increase its transaction price if the energy efficiency improvements are capitalized into the value of the home. The relationship between energy efficiency and transaction prices in the Fairbanks and Anchorage, Alaska residential real estate markets is examined. Using a hedonic pricing framework and difference-in-differences analysis, the impact of the Alaska Home Energy Rebate program on the transaction prices of single-family homes in the Fairbanks and Anchorage housing markets from 2008 through 2015 is examined. The results indicate that compared to homes that did not complete the program, homes that completed the program sell for a statistically significant price premium between 15.1% and 15.5% in the Fairbanks market and between 5% and 11% in the Anchorage market. A hedonic pricing framework is used to relate energy efficiency ratings and transaction prices of homes in the Fairbanks and Anchorage residential real estate markets from 2008 through 2015. The results indicate that homes with above-average energy efficiency ratings sell for a statistically significant price premium between 6.9% and 17.5% in the Fairbanks market and between 1.8% and 6.0% in the Anchorage market.
    • Variability in foraging by humpback whales (Megaptera novaenangliae) on the Kodiak, AK, feeding ground

      Wright, Dana Louise; Witteveen, Briana; Quinn, Terrance II; Wynne, Kate; Horstmann-Dehn, Lara (2014-12)
      The North Pacific humpback whale (Megaptera novaeangliae) population has been growing rapidly following a moratorium on commercial whaling in 1986. Knowledge of humpback whale foraging on feeding grounds is becoming increasingly important as the growing population consumes more prey, including economically important commercial fishes. The goal of this thesis is to better understand how marine resources are shared among the growing humpback whale population and sympatric apex predators, including western Steller sea lions (SSLs; Eumetopias jubatus), on the Kodiak, AK, feeding ground. To address this, we explored spatial and temporal (inter-annual and within-feeding season) variability in summer foraging by humpback whales along the eastern side of the Kodiak Archipelago as described by stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios of humpback whale skin (n = 118; 2004-2013). We found evidence for the existence of two sub-aggregations of humpback whales ('North', 'South') on the feeding ground that fed at different trophic levels (TLs) throughout the study period. Bayesian stable isotopic mixing models were applied to describe the proportional contribution of prey species to the diet of humpback whales for the two regions. The 'North' region humpback whale sub-aggregation consumed a mixed diet of euphausiids and forage fishes, whereas the 'South' region sub-aggregation foraged predominantly on euphausiids. Results from these analyses were compared to diet composition of Kodiak SSLs of the recovering western SSL population estimated from fecal samples (n = 656; 2000-2005), to explore spatial differences in the degree of overlap in trophic niche between these predators. Western SSLs underwent a marked population decline starting in the late 1970's and have shown slow and variable signs of recovery. Regional variability in SSL and humpback whale diets resulted in a higher degree of overlap in trophic niche, although not biologically significant (Ojk < 0.60), for individuals in the 'North' region compared with the 'South'. However, humpback whale consumption appears to overlap considerably with multiple piscivorous fishes that are prominent prey for SSLs, and thus, consumption by humpback whales may indirectly impact the prey resources of SSLs. Therefore, this study highlights the complexity of the Kodiak ecosystem and suggests consumption by an increasing population of humpback whales has the potential to indirectly impact the recovery of SSLs on a regional scale depending on the biomass of prey species and diet composition of humpback whales in the region.
    • Variability In Population Trends, Life History Characteristics, Amd Milk Composition Of Northern Fur Seals In Alaska

      Hayden, Alison Banks; Springer, Alan; Iverson, Sara; Castellini, Michael (2012)
      The northern fur seal population on the Pribilof Islands has been declining since the 1960s and is now less than 30% of its former size. Chapter 1 examines factors that might cause a population to decrease to such an extent and concludes that only nutritional limitation caused by climate change or commercial fisheries, predation by killer whales, or a combination of factors that includes conditions in the North Pacific during the winter were possible explanations. Chapter 2 reports the seasonal patterns in proximate composition of fur seal milk between St. Paul Island (one of the Pribilof Islands) and Bogoslof Island (an increasing population) to understand the energy requirements of lactation and the energetics of pup growth and body condition at weaning. Factors that caused variability in milk composition included days postpartum, time ashore, individual phenotype, island and preceding trip duration. Average milk lipid increased from 45.5+/-0.7% to 53.8+/-1.0% at St. Paul and from 45.8+/-0.7% to 57.3+/-0.8% at Bogoslof between July and October, while average milk protein remained relatively stable ranging between 10.0% and 10.5%. The lipid content of northern fur seal milk near peak lactation is the highest reported among otariid seals and among the highest known for all mammals.
    • Variability in Steller sea lion (Eumetopias jubatus) prey quality in Southeastern Alaska

      Vollenweider, Johanna Jill; Kelly, Brendan; Adkison, Milo; Stekoll, Michael (2005-05)
    • Variability In The Circulation, Temperature, And Salinity Fields Of The Eastern Bering Sea Shelf In Response To Atomospheric Forcing

      Danielson, Seth Lombard; Weingartner, Thomas; Aagaard, Knut; Coyle, Kenneth; Hedstrom, Katherine; Kowalik, Zygmunt (2012)
      Although the Bering Sea shelf plays a critical role in mediating the global climate and supports one of the world's largest fisheries, fundamental questions remain about the role of advection on its salt, fresh water, heat and nutrient budgets. I quantify seasonal and inter-annual variability in the temperature, salinity and circulation fields. Shipboard survey temperature and salinity data from summer's end reveal that advection affects the inter-annual variability of fresh water and heat content: heat content anomalies are set by along-shelf summer Ekman transport anomalies whereas fresh water content anomalies are determined by wind direction anomalies averaged over the previous fall, winter and early spring. The latter is consistent with an inverse relationship between coastal and mid-shelf salinity anomalies and late summer -- winter cross-shelf motion of satellite-tracked drifters. These advection anomalies result from the position and strength of the Aleutian Low pressure system. Mooring data applied to the vertically integrated equations of motion show that the momentum balance is primarily geostrophic within at least one external deformation radius of the coast. Local accelerations, wind stress and bottom friction account for < 20% (up to 40%) of the along- (cross-) isobath momentum balance, depending on location and season. Wind-forced surface Ekman divergence is primarily responsible for flow variations. The shelf changes abruptly from strong coastal convergence conditions to strong coastal divergence conditions for winds directed to the south and for winds directed to the west, respectively, and substantial portions of the shelf's currents reorganize between these two modes of wind forcing. Based on the above observations and supporting numerical model integrations, I propose a simple framework for considering the shelf-wide circulation response to variations in wind forcing. Under southeasterly winds, northward transport increases and onshore cross-isobath transport is relatively large. Under northwesterly winds, onshore transport decreases or reverses and nutrient-rich waters flow toward the central shelf from the north and northwest, replacing dilute coastal waters that are carried south and west. These results have implications for the advection of heat, salt, fresh water, nutrients, plankton, eggs and larvae across the entire shelf.
    • Variability Of Pink Salmon Family Size Has Implications For Conservation And Management Models

      Geiger, Harold Joseph, Iii; Gharrett, A. J. (2002)
      In several populations of pink salmon, the short-term dynamics population size was related to both the mean and variance of individual family sizes, because not all families were equally productive. In the marine lifestage, population increases came disproportionately from the most productive families, especially in populations with the highest average marine survival. Moreover, the trait of marine survival itself had a statistically detectable genetic component. This implies that the most favored phenotypes change from generation to generation, and that the marine environment is unpredictable and changing. These results, together with laboratory studies of freshwater survival and measurements of wild pink salmon in Prince William Sound, Alaska, seemed to indicate that family-specific variation in marine survival and variation in egg retention within the redd were the most important potential influences on variation of pink salmon family size in the studied populations, when density was controlled to intermediate levels. These results provide more justification for maintaining stock sizes at intermediate or high levels, and for protecting metapopulation structure. These results also show the importance of variation and instability in the recruitment process of Pacific salmon, and highlight the inadequacy of current models of salmon recruitment, which emphasize stability and long-term averages.
    • A variable-boundary numerical tidal model

      Mungall, J. C. H. (1970-05)
      A numerical tidal model using equations developed by Hansen (1952) and Yuen (1967) is automated to the point where a potential user need not undertake extensive reprogramming. The user adds to the program only those cards needed to specify tides at input points as a function of time; the application of the relevant calculations at each grid point being controlled by an integer matrix that corresponds to the inlet boundary. A sample problem is covered in detail and applications of the model to the M₂ tide of the Gulf of California, and to a hypothetical mean tide in Cook Inlet are shown.
    • Variation in abundance and physiological status of juvenile chum salmon (Oncorhynchus keta) in relation to marine factors in Southeast Alaska

      Kohan, Michael L.; McPhee, Megan V.; Mundy, Phillip R.; Orsi, Joseph A.; Mueter, Franz J. (2015-08)
      Little is known about the mechanisms influencing the critical early life stages of juvenile chum salmon (Oncorhynchus keta) from coastal to offshore marine waters. There is mounting evidence to suggest that fluctuations in early marine conditions affect juvenile salmon physiological status and year class strength. We investigated relationships of a suite of marine factors at local, regional, and basin scales to the physiological status and abundance of juvenile chum salmon in northern Southeast Alaska (SEAK) from 1997-2013. Correlation analyses were used to identify potential mechanisms influencing year class strength. Marine factors at the local scale were correlated to the observed physiological status of juvenile chum salmon: average June/July wind speed was negatively correlated to weight-at-length residuals, sea surface temperatures in July were positively correlated with length, and the June mixed-layer depth was positively correlated to the energy density of juvenile chum salmon in July. Marine factors at the regional scale influenced juvenile chum salmon abundance: freshwater discharge was positively correlated whereas upwelling was negatively correlated with abundance, linking high abundance to characteristics of strong Aleutian Low (AL) climatic conditions. Comparisons of juvenile chum salmon physiological status were also made between: 1) SEAK habitats (Icy Strait and the Eastern Gulf of Alaska, EGOA), 2) stock groups (hatchery and wild), and 3) years 2010 and 2011 possible mechanisms influencing productivity of chum salmon. Between habitats, length of juvenile chum salmon did not differ. However, both weight-at-length residuals and energy density values were significantly higher in the EGOA, irrespective of year, indicating juvenile salmon allocate energy to somatic growth in Icy Strait, while the EGOA may serve as a habitat for juvenile chum salmon to store energy as lipids. Between chum salmon stocks, wild stocks were shorter and had higher weight-at-length residuals than hatchery stocks. Between years, the 2010 ocean year was associated with a strong AL that coincided with higher physiological status of juvenile chum salmon and relatively higher returning adult commercial harvests and ocean survival of hatchery fish compared to the 2011 ocean year. Our results suggest differences in juvenile chum salmon physiological status in 2010 and 2011 coincided with positive and negative anomalies of the coupled ocean-atmosphere system, which were linked to previous winter environmental conditions, and have the potential to be used as a predictive salmon management tool to forecast year class strength in SEAK.
    • Variation in age and size at maturity of Lake Clark, Alaska sockeye salmon

      Benolkin, Elizabeth B.; Margraf, Joseph; Woody, Carol Ann; Adkison, Milo (2009-12)
      Salmon returning to Lake Clark, Alaska are a valuable subsistence, commercial and ecological resource, and are an important component of the larger Kvichak River escapement. Average escapement to the Kvichak River declined sharply during 1996-2005, prompting studies to investigate age and size at maturity, key life history traits of salmon linked to reproductive success and survival. We examined potential factors which may influence sockeye salmon Oncorhynchus nerka age and size at maturity: spawning habitat and ocean environment, and examined variation in both traits over time. Sockeye salmon age and length at maturity differed among spawning locations and between brood years, but no consistent patterns were observed among habitat types. Age and length at maturity differed over time; the proportion of older marine age 3 fish was larger in recent brood years, while fish were smaller during 1997-2001 compared to 1976-1980. Sea surface temperatures and coastal upwelling appeared to be important indicators of fish length, highlighting the importance of the ocean environment in salmon growth. These results demonstrate the complexity and importance of both the freshwater and ocean ecosystems in variation in age and size at maturity, and indicate that trends may not necessarily be similar among systems or years.
    • Variation of agonistic behavior and morphology among juvenile chinook salmon (Oncorhynchus tshawytscha) of hatchery, wild, and hybrid origin under common rearing conditions

      Lang Wessel, Maria Elena (2004-05)
      Hatcheries play an important role in the enhancement of Pacific salmon (genus Oncorhynchus) as a resource, but genetic and phenotypic divergence trom wild populations may occur as a result of founder effects, genetic drift and/or domestication. In this study, agonistic behavior, ability to establish dominance, and morphology were compared among juveniles of chinook salmon (Oncorhynchus tshawytscha) that have experienced five generations of hatchery ranching culture, juveniles derived trom the wild founding stock, and second generation hybrids of the two lines. The parent generation of all lines was cultured in the same hatchery environment as the juveniles tested. Behavioral observations were conducted in replicate artificial stream tanks; hatchery and hybrid fish were significantly more aggressive than wild derived fish. No difference was detected in the ability of fish lines to win dyadic dominance contests. Thin-plate spline analysis was used to characterize morphometric variation; hatchery and wild derived juveniles differed significantly. Canonical discriminant analysis correctly classified 88% of hatchery fish and 90% of wild derived fish. Morphologically, hybrid fish were significantly different trom both hatchery and wild derived fish. These results suggest that the differences observed between lines are genetic in origin although the sources of the divergence were not conclusively identified.
    • Variation of electron and ion density distribution along earth's magnetic field line deduced from whistler mode (wm) sounding of image/rpi satellite below altitude 5000 km

      Hazra, Susmita; Truffer, Martin; Simpson, William; Newman, David; Braddock, Joan (2015-05)
      This thesis provides a detailed survey and analysis of whistler mode (WM) echoes observed by IMAGE/RPI satellite during the years 2000-2005 below the altitude of 5000 km. Approximately 2500 WM echoes have been observed by IMAGE during this period. This includes mostly specularly reflected whistler mode (SRWM) echoes and ~400 magnetospherically reflected whistler mode (MRWM) echoes. Stanford 2D raytracing simulations and the diffusive equilibrium density model have been applied to 82 cases of MRWM echoes, observed during August-December of the year 2005 below 5000 km to determine electron and ion density measurements along Earth's magnetic field line. These are the first results of electron and ion density measurements from WM sounding covering L-shells ~1.6-4, a wide range of geomagnetic conditions (Kp 0+ to 7), and during solar minima (F10.2~70-120) in the altitude range 90 km to 4000 km. The electron and ion density profiles obtained from this analysis were compared with in situ measurements on IMAGE (passive recording; electron density (Ne)), DMSP (~850 km; Ne and ions), CHAMP (~350 km; Ne), Alouette (~500-2000 km; Ne and ions), ISIS-1, 2 (~600-3500 km; Ne, ions), AE (~130-2000 km; ions) satellites, bottom side sounding from nearby ionosonde stations (Ne), and those by GCPM (Global Core Plasma Model), IRI-2012 (International Reference Ionosphere). Based on this analysis it is found that: (1) Ne shows a decreasing trend from L-shell 1.6 to 4 on both the day and night sides of the plasmasphere up to altitude ~1000 km, which is also confirmed by the GCPM and IRI-2012 model. (2) Above ~2000 km altitude, GCPM underestimates Ne by ~30-90% relative to RPI passive measurements, WM sounding results. (3) Below 1500 km, the Ne is higher at day side than night side MLT (Magnetic Local Time). Above this altitude, significant MLT dependence of electron density is not seen. (4) Ion densities from WM sounding measurements are within 10-35% of those from the Alouette, AE, and DMSP satellites. (5) The effective ion mass in the day side is more than two times higher than night side below altitude ~500 km. (6) The O⁺/H⁺ and O⁺/(H⁺+H⁺+) transition heights at day side are ~300-500 km higher than night side; the transition heights from the IRI-2012 model lie within the uncertainty limit of WM sounding for night side, but for day side (L-shell>2.5) they are 200 km higher than WM uncertainty limits. (7) foF2 (F2 peak plasma densities) from ionosonde stations and the IRI-2012 model are ~1.5-3 MHz higher than those from WM sounding during daytime. These measurements are very important as the ion density profile along geomagnetic field lines is poorly known. They can lead to a better understanding of global cold plasma distribution inside the plasmasphere at low altitude and thereby bridge the gap between high topside ionosphere and plasmasphere measurements. These results will provide important guidance for the design of future space-borne sounders in terms of frequency and virtual range, in order to adequately cover ion density measurements at low altitudes and wide range of MLTs, solar and geophysical conditions.
    • Variation of the plasmaspheric field-aligned electron density and ion composition as a function of geomagnetic storm activity

      Reddy, Amani; Sonwalkar, Vikas S.; Watkins, Brenton; Hawkins, Joseph G.; Bogosyan, Seta (2015-08)
      Whistler mode (WM) radio sounding is a powerful new method that provides measurement of both field-aligned electron and ion densities from the satellite altitude (<5,000 km) down to 90 km. Using radio sounding data from the Radio Plasma Imager (RPI) onboard the IMAGE (Imager for Magnetosphere-to-Aurora Global Exploration) satellite, this thesis presents a systematic and efficient approach to implement the whistler mode radio sounding method and discusses the uncertainties in the measured plasma parameters. The sounding method is applied to obtain the first measurements of plasmaspheric field-aligned electron density and ion composition as a function of geomagnetic storm activity during the mid-August to September 2005 period. This period included several geomagnetic storms of varying strength that occurred in succession. The plasmapause was located at L~2.4 during the onset and main phases of the storms. The whistler mode sounding results were augmented by measurements from the CHAMP and DMSP satellites, and ground ionosonde stations during the same period. On the day-side, at L~2, as a function of storm activity the following general results were found: (1) The electron density, relative ion concentrations, and O⁺/H⁺ transition height underwent temporal changes as a function of geomagnetic storm activity, and each species had different temporal behavior thus indicating different recovery times. (2) O⁺/=H⁺ transition height increased by ~200-300 km during the onset, main and early recovery phases of the storms. (3) Variation in the electron density below the O⁺=H⁺ transition height was different than that above. (4) Electron density at F2 peak increased during the onset or main phase of storms followed by a decrease in the recovery phase. (5) Electron density above O+=H+ transition height increased either in the onset or on the first day of recovery phase followed by a decrease. (6) αH₊ decreased during the onset, main and/or early recovery phases of storms; αo₊ increased in the early recovery phases of the storms; αHe₊ varied in a complex manner but in general there was an increase in αHe₊ during the onset phases and decrease in αHe₊ during the recovery phases of the storms. (7) When storms occurred in succession in an interval of roughly less than a day, the latter storms had little or no effect on the electron density and/or ion composition. On the night-side, WM sounding data was sparse. In the case of one moderate storm, we found that 3 days after the storm, at L~2.3, electron density at F2 peak and relative ion concentrations (at all altitudes) were comparable to those before the storm, whereas electron density above O⁺=H⁺ transition height decreased. WM sounding results for the day-side and night-side were in agreement with measurements from CHAMP (~350 km) and DMSP (~850 km). Whistler mode sounding results coupled with physics-based models will allow: (a) investigation of the role of thermospheric winds, dynamo electric fields, and storm time electric fields in causing the variations in electron and ion densities and (b) testing of current theories and validating physics-based models of the thermosphere-ionosphere-magnetosphere.
    • Variational anodic oxidation of aluminum for the formation of conically profiled nanoporous alumina templates

      Wallace, Patrick D. (2012-05)
      Anodic oxidation of metals, otherwise known as anodization, is a process by which the metal in question is intentionally oxidized via an electrochemical reaction. The sample to be oxidized is connected to the anode, or positive side of a DC power source, while a sample of similar characteristics is attached to the cathode or negative side of the same power source. Both leads are then immersed in an acidic solution called the electrolyte and a current is passed between them. Certain metals such as aluminum or titanium anodized in this way form a porous oxide barrier, the characteristics of which are dependent on the anodization parameters including the type of acid employed as the electrolyte, pH of the electrolyte, applied voltage, temperature and current density. Under specific conditions the oxide formed can exhibit highly ordered cylindrical nanopores uniformly distributed in a hexagonal pattern. In this way anodization is employed as method for nanofabrication of ordered structures. The goal of this work is to investigate the effects of a varied potential difference on the anodization process. Specifically to affect a self-assembled conical pore profile by changing the applied voltage in time. Although conical pore profiles have been realized via post-processing techniques such as directed wet etching and multi-step anodization, these processes result in pore dimensions generally increasing by an order of magnitude or more. To date there has been reporting on galvanostatic or current variations which directly effected the resulting pore profiles, but to our knowledge there has not been a reported investigation of potentiostatic or voltage variation on the anodization process. We strive to realize a conical pore profile in process with the traditional two-step anodization method while maintaining the smallest pore dimensions possible. Pores having diameters below 20nm with aspect ratios about 1.0 would be ideal as those dimensions would be much closer to some of the characteristic lengths governing the quantum confined spatial domain. Thus we set out to answer the question of what effect a time varied potential difference will have on the traditional two-step anodization method, a technique we refer to as variational iodization, and if in fact conically profiled nanopores can be realized via such a technique.
    • Variations In Ice Flow And Glaciers Over Time And Space

      Elsberg, Daniel Harry; Harrison, William D. (2003)
      Ice flows and glaciers change over many time and spatial scales. Glacier surfaces evolve over decades, and this change affects the glacier-climate interaction. When a mass balance is computed using an outdated map, that computation does not reveal actual mass change. We present a method by which a mass balance computed with an outdated map can be transformed into actual mass change. While the actual volume change of a glacier is relevant to hydrological studies, the change that would have occurred on a static surface is more relevant to certain glacier dynamics problems and most climate problems. We term this the reference-surface balance and propose that such a balance is better correlated to climatic variations than the conventional one. Ice responds to stresses over time scales from seconds to millennia. We observed this using two independent strain-gauge systems to measure the strain rates as functions of depth and time at Siple Dome, Antarctica. One system employed optical fibers to measure annual strain rates over 175 m depth intervals. The other used one-meter resistance wires to measure strain approximately hourly at discrete depths. The long-term average strain rates from the two systems agreed to within 16%. The time-dependent strain rates measured beneath the divide by the resistance-wire gauges included intermittent strain events lasting up to 24 hours. We used the results from each system to compute an age-depth relationship assuming a time-independent ice flow geometry. Equilibrium line altitudes are related to climate, and they vary from year to year and among neighboring glaciers. We measured a regional pattern of equilibrium lines using remote sensing. Our goals were to evaluate the accuracy of such measurements, and to assess the spatial and temporal variability of the resulting data. Individual glacier equilibrium line altitudes varied by 100 m relative to a smoothed surface, and inter-annual variations in equilibrium line altitudes at one glacier were 74 m. A map of the regional pattern of equilibrium line altitudes shows variations of 1000 meters from the south to the north side of the range, but no major trend from east to west.
    • Variations on a theme: the Benjy section of 'The sound and the fury' in black and white, color and hypertext

      Porter, Thomas Albert (2000-05)
      The Benjy section of William Faulkner's 'The sound and the fury' presents reader's with a shattered chronology. Meaning, in the original, arises from the reader's internal creation of a linear chronology, the internal linking of discreet events into larger sequences of events. Applying color to the section along chronological lines allows for the reader to assemble a more coherent chronology of the section internally by allowing for more easily intuited links. Transforming the Benjy section into a hypertext incorporates the links between Events directly. These three variations, black and white print, color print, and hypertext all demonstrate and highlight different aspects of the section's inherent complications, as well as demonstrating that the original text's abandonment of traditional narrative time was a serious and direct challenge to the medium of print itself.
    • Vascular endothelial growth factor's angiogenic role in tumor growth and metastasis

      Kemp, Scott W.; Duffy, Lawrence K.; Clausen, Tom; Reynolds, Arleigh (2005-05)
      Angiogenesis and vasculogenesis are two very important processes in the development and maintenance of mammalian health. All structures of the body (human or animal) need certain essential elements in order to live thrive and maintain. The angiogenic role is to supply and support tissue with ample vasculature, thus providing a route of access for the transportation of essential nutrients and the removal of waste in a sustained fashion. Just like normal tissue, tumorogenic tissue is no exception; neoplastic tissue has the same nutritional requirements which must be supported via vascularization. Vascular endothelial growth factor (VEGF) has been shown to be a key mediating factor in the underlying cascade of chemical events leading to angiogenesis, which makes it a very important precursor molecule for early neoplasia detection. The overall purpose of this study was to establish circulatory baseline VEGF levels in healthy dog models. Baseline levels of VEGF in plasma will aid as a model in detection, comparison and evaluating of disease progression in sled dogs. There were significant differences between male and female dogs and exercising males and exercising females. A significant factor affecting baseline levels was gender. In addition there is some data which suggest that breed may playa role in baseline VEGF levels.
    • Vegetation reconstruction and climate evolution of Lake Dood, Darhad Basin, Northern Mongolia, over the past 4,500 years

      Wang, Yiming (2004-05)
      A semi-quantitative pollen index and stable isotopes of carbon and nitrogen are used to reconstruct late Holocene changes in moisture availability in the Darhad Basin, northern Mongolia. Palynomorphs extracted from cores of lake Dood indicate that the surrounding Darhad Basin was much wetter at 4,200 cal. yrs B.P. Beginning at 2,900 cal. yrs B.P., humidity in the Darhad Basin decreased until 300 cal. yrs B.P. Humidity and warmth returned briefly during the Medieval Warm Epoch, from 1,370 to 930 cal yrs B.P. (AD. 580 to 892). Increasing proportions of forest to steppe pollen types suggests a response to warmer summer temperatures and/or increased moisture during the 20th century warming. Differences in lake levels between lakes Dood, Telmen (300km to the south), and Hövsgöl (60km to the east), suggest that available moisture varies over short distances. Temperature changes driven by solar insolation appear to exert significant control over the regional water budgets of both lake Telmen and lake Hövsgöl, whereas moisture availability in the lake Dood region is affected by changes in atmospheric circulation over Eurasia.