University of Alaska Fairbanks
  • Fairbanks, Alaska, United States
Recent publications
For more than 50 years, government programmes in the USA have been in place to help those in need have consistent access to food and education. However, questions have surfaced regarding whether or not these support impact traditional ways, such as cultural activities, food preferences, and overall health, particularly for Indigenous populations. In this paper, we share insights voiced by Alaska Native Elders in the Yukon-Kuskokwim region of Alaska and their perceptions of regulations, assistance, and the impact government assistance programmes have had on their culture. Elders raised concerns so that those administering these programmes will consider how best to meet food security and education needs without interfering with Indigenous cultural practices and traditional lifestyle.
In Southeast Alaska (SE-AK), rapid ground uplift of up to 3 cm/yr has been observed associated with post-Little Ice Age glacial isostatic adjustment (GIA). Geodetic techniques such as global navigation satellite system (GNSS) and absolute gravimetry have been applied to monitor GIA since the last 1990s. Rheological parameters for SE-AK were determined from dense GNSS array data in earlier studies. However, the absolute gravity rate of change observed in SE-AK was inconsistent with the ground uplift rate, mainly because few gravity measurements from 2006 to 2008 resulted in imprecise gravity variation rates. Therefore, we collected absolute gravity data at six gravity points in SE-AK every June in 2012, 2013, and 2015, and updated the gravity variation rate by reprocessing the absolute gravity data collected from 2006 to 2015. We found that the updated gravity variation rate at the six gravity points ranged from −2.05 to −4.40 $$\upmu$$ μ Gal/yr, and its standard deviation was smaller than that reported in the earlier study by up to 88 %. We also estimated the rheological parameters under the assumption of the incompressible Earth to explain the updated gravity variation rate, and their optimal values were determined to be 55 km and $$1.2 \times 10^{19}$$ 1.2 × 10 19 Pa s for lithospheric thickness and upper mantle viscosity, respectively. These optimal values are consistent with those independently obtained from GNSS observations, and this fact indicates that absolute gravimetry can be one of the most effective methods in determining sub-surface structural parameters associated with GIA accurately. Moreover, we utilized the gravity variation rates for estimating the ratio of gravity variation to vertical ground deformation at the six gravity points in SE-AK. The viscous ratio values were obtained as −0.168 and −0.171 $$\upmu$$ μ Gal/mm from the observed data and the calculated result, respectively. These ratios are greater (in absolute) than those for other GIA regions (−0.15 to −0.16 $$\upmu$$ μ Gal/mm in Antarctica and Fennoscandia), because glaciers in SE-AK have melted more recently than in other regions. Graphical Abstract
Power ultrasonic assisted reservoir modification is a promising technique for enhanced coalbed methane recovery. The current studies confirm the coal structural alteration and the improvement of gas deliverability in coal pores with ultrasound stimulation. However, the in-site performance of ultrasound-assisted CBM production has not yet been revealed. In the current study, the in-situ antireflection test was conducted with high power ultrasound ∼18 kW in underground coal seam, and the antireflection performance was evaluated by measuring the borehole drainage gas data in the field test zone. The result shows, within 40 days’ drainage after ultrasonic antireflection in coal seam, the average gas concentration of single borehole in the experimental group increased by 81.4% ∼ 227.3% than that in control group, the average borehole gas flowrate has a 20% ∼106% improvement over the control group, and the pure methane production in single borehole increased by about 3.83 times. The ultrasonic anti-reflection influence radius exceeds 8 m in the coalseam with water injection in this study, and the increment of methane production in single borehole decreases with the distance increase from the ultrasound source, which is due to the energy attenuation of ultrasound propagation in the porous coalseam. This study preliminarily demonstrates the on-site implementability and effectiveness of power ultrasound in enhancing coalbed methane recovery.
Examining relationships between formal and informal institutions for governing small-scale fisheries may reveal pathways for effectively engaging resource users in management. This study explored formal and informal institutions for management of rockfish (Sebastes spp.) fisheries in the Gulf of Alaska. Forty-three experts (fishers and agency staff) were interviewed about their engagement with rockfish management. We analyzed interactions and gaps between formal and informal management institutions using the Inter-Institutional Gap (IIG) framework. Participation in the State of Alaska Board of Fisheries (BOF) process, a formal management institution, was viewed by some experts as more effective for enacting regulatory change, compared to informal institutions. However, fishers who were deterred from engaging with the BOF by complex bureaucratic processes tended to favor informal interactions with the Alaska Department of Fish and Game (ADF&G) through visits to local offices and communication with port samplers. Formal institutional gaps identified by experts included transparency issues regarding regulatory decisions and/or interpretation, underrepresentation of recreational and subsistence harvesters in the BOF process, complexity of regulations, and bureaucratic barriers to coordination between the Sport and Commercial divisions of ADF&G. Informal institutions of self-governance, such as stewardship actions taken by fishers to reduce bycatch and minimize harm to incidentally caught fish, were identified by fishers and agency staff as important to rockfish fishery sustainability. Communication gaps in rockfish management may also be addressed by strengthening informal institutions that build trust and relationships between fishers and agency staff, such as collaborative research to coproduce knowledge about rockfish ecology.
The transition from fossil-fuel based power generation to renewable energy is well underway; however, this transition is highly uneven and not all regions and communities are engaging equally. The circumpolar north is one region where disparities in the uptake of community renewable energy (CRE) projects is evident. Many Northern, remote communities are not connected to national electricity grids and as a result, rely heavily on imported and expensive fuels for power generation. However, within this context, there are places in the US state of Alaska that have forged a leading path toward CRE. This paper investigates why some remote communities develop renewable energy projects while others do not. Using Qualitative Comparative Analysis (QCA), we compare 24 remote communities in Alaska to identify the combination of explanatory factors that can lead to CRE. We first identified 37 potential conditions, from which we drew three primary explanatory factors: community capacity, electricity subsidies, and pooled resources. Results show the absence of large electricity subsidies is a necessary condition to the development of CRE. It also shows that the presence of subsidies (above a state-wide program) stymies transitions. We also found that particular combinations of the absence of large subsidies, community capacity, and working collaboratively to pool resources across communities, were found to be key explanatory variables in the establishment of CRE. These findings may have implications for other communities both in the Circumpolar North and elsewhere, clarifying the conditions that support CRE development.
Plain Language Summary Previous studies have shown that intense low frequency electromagnetic waves called dispersive Alfvén waves (DAWs) are a prominent occurrence in the nightside equatorial inner magnetosphere during active geomagnetic storm time conditions. In the inner magnetosphere DAWs have ion gyroradius transverse scales and thus are generally referred to as kinetic Alfvén waves. These waves are invariably associated with energized field‐aligned electrons that are often counterstreaming along the magnetic field. Characteristic of their field‐aligned counterstreaming nature, these electrons are associated with highly anisotropic plateaued cigar shaped velocity space distribution functions. How these distribution function signatures are locally produced by the interaction of electrons in the fields of these waves are not fully understood. We use satellite observations combined with computer simulations to study how electrons get energized by these waves. Particular attention is focused on traveling modes, which we show occur at the interface of energetic plasma injections into the inner magnetosphere. We determined that the features of the observed energized electrons are best reproduced when cold electrons (with origins in the ionosphere) are considered in the simulations and that the magnitude of the energization is a sensitive function of the fraction of these cold electrons.
Isolating seasonal deformation from Interferometric Synthetic Aperture Radar (InSAR) time‐series is critical to quantitative understanding the freeze‐thaw processes in permafrost regions. Physics‐ or statistics‐based approaches have been developed to extract seasonal deformation, yet both constraining their evolution in time domain, and thus impeded the quantification of their amplitude variability especially over large scales. By applying Independent Component Analysis (ICA) on Sentinel‐1 InSAR measurements during 2015–2019 on the central Qinghai‐Tibet Plateau, we reveal that the averaged seasonal deformation is increasing with a linear trend of around 0.17 cm/year. The growing seasonal amplitude is attributed to an 8 cm increase of the Equivalent Water Thickness in the active layer. The results demonstrate the capability of ICA‐based decomposition on isolating freeze‐thaw‐related deformation from other components. The large‐scale spatial distribution of varied seasonal deformation can provide new insight into quantifying the water mass balance in vast permafrost regions.
Plain Language Summary The ocean mitigates the extent of global warming by absorbing a portion of the carbon dioxide gas (CO2) released into the atmosphere by human activities. However, this comes at a cost to ocean health because the uptake of this anthropogenic CO2 causes changes in ocean chemistry, called ocean acidification (OA), that can be detrimental to marine ecosystems. This study explores how OA metrics have changed in the upper waters of the open North Pacific Ocean and coastal California Current Large Marine Ecosystem (CCLME). We focus on the CCLME due to its global importance and economically important fisheries. We find that different OA metrics exhibit different patterns of change with depth in the water column due to the natural, background ocean chemistry. One such metric shows that there is now more subsurface water containing CO2 levels elevated enough to threaten the health of marine organisms than there was before the anthropogenic CO2 addition. Our finding of expanded volumes of water with high‐CO2 levels near the coast is important to consider as a source of stress for marine organisms living both on the seafloor and in the water column.
Water, energy, and food are all essential components of human societies. Collectively, their respective resource systems are interconnected in what is called the “nexus”. There is growing consensus that a holistic understanding of the interdependencies and trade-offs between these sectors and other related systems is critical to solving many of the global challenges they present. While nexus research has grown exponentially since 2011, there is no unified, overarching approach, and the implementation of concepts remains hampered by the lack of clear case studies. Here, we present the results of a collaborative thought exercise involving 75 scientists and summarize them into 10 key recommendations covering: the most critical nexus issues of today, emerging themes, and where future efforts should be directed. We conclude that a nexus community of practice to promote open communication among researchers, to maintain and share standardized datasets, and to develop applied case studies will facilitate transparent comparisons of models and encourage the adoption of nexus approaches in practice.
Increased industrial development in the Arctic has led to a rapid expansion of infrastructure in the region. Localized impacts of infrastructure on snow distribution, road dust, and snowmelt timing and duration feeds back into the coupled Arctic system causing a series of cascading effects that remain poorly understood. We quantify spatial and temporal patterns of snow-off dates in the Prudhoe Bay Oilfield, Alaska, using Sentinel-2 data. We derive the Normalized Difference Snow Index (NDSI) to quantify snow persistence in 2019-2020. The Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) were used to show linkages of vegetation and surface hydrology, in relationship to patterns of snowmelt. Newly available infrastructure data was used to analyze snowmelt patterns in relation infrastructure. Results show a relationship between snowmelt and distance to infrastructure varying by use and traffic load, and orientation relative to the prevailing wind direction (up to 1 month difference in snow-free dates). Post-snowmelt surface water area showed a strong negative correlation (up to -0.927) with distance to infrastructure. Results from field observations indicate an impact of infrastructure on winter near-surface ground temperature and snow depth. This study highlights the impact of infrastructure on a large area beyond the direct human footprint and the interconnectedness between snow-off timing, vegetation, surface hydrology, and near-surface ground temperatures.
Zooplankton plays a major role in ocean food webs and biogeochemical cycles, and provides major ecosystem services as a main driver of the biological carbon pump and in sustaining fish communities. Zooplankton is also sensitive to its environment and reacts to its changes. To better understand the importance of zooplankton, and to inform prognostic models that try to represent them, spatially-resolved biomass estimates of key plankton taxa are desirable. In this study we predict, for the first time, the global biomass distribution of 19 zooplankton taxa (1-50 mm Equivalent Spherical Diameter) using observations with the Underwater Vision Profiler 5, a quantitative in situ imaging instrument. After classification of 466,872 organisms from more than 3,549 profiles (0-500 m) obtained between 2008 and 2019 throughout the globe, we estimated their individual biovolumes and converted them to biomass using taxa-specific conversion factors. We then associated these biomass estimates with climatologies of environmental variables (temperature, salinity, oxygen, etc.), to build habitat models using boosted regression trees. The results reveal maximal zooplankton biomass values around 60°N and 55°S as well as minimal values around the oceanic gyres. An increased zooplankton biomass is also predicted for the equator. Global integrated biomass (0-500 m) was estimated at 0.403 PgC. It was largely dominated by Copepoda (35.7%, mostly in polar regions), followed by Eumalacostraca (26.6%) Rhizaria (16.4%, mostly in the intertropical convergence zone). The machine learning approach used here is sensitive to the size of the training set and generates reliable predictions for abundant groups such as Copepoda (R2 ≈ 20-66%) but not for rare ones (Ctenophora, Cnidaria, R2 < 5%). Still, this study offers a first protocol to estimate global, spatially resolved zooplankton biomass and community composition from in situ imaging observations of individual organisms. The underlying dataset covers a period of 10 years while approaches that rely on net samples utilized datasets gathered since the 1960s. Increased use of digital imaging approaches should enable us to obtain zooplankton biomass distribution estimates at basin to global scales in shorter time frames in the future.
The increased fraction of first year ice (FYI) at the expense of old ice (second-year ice (SYI) and multi-year ice (MYI)) likely affects the permeability of the Arctic ice cover. This in turn influences the pathways of gases circulating therein and the exchange at interfaces with the atmosphere and ocean. We present sea ice temperature and salinity time series from different ice types relevant to temporal development of sea ice permeability and brine drainage efficiency from freeze-up in October to the onset of spring warming in May. Our study is based on a dataset collected during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 and 2020. These physical properties were used to derive sea ice permeability and Rayleigh numbers. The main sites included FYI and SYI. The latter was composed of an upper layer of residual ice that had desalinated but survived the previous summer melt and became SYI. Below this ice a layer of new first-year ice formed. As the layer of new first-year ice has no direct contact with the atmosphere, we call it insulated first-year ice (IFYI). The residual/SYI-layer also contained refrozen melt ponds in some areas. During the freezing season, the residual/SYI-layer was consistently impermeable, acting as barrier for gas exchange between the atmosphere and ocean. While both FYI and SYI temperatures responded similarly to atmospheric warming events, SYI was more resilient to brine volume fraction changes because of its low salinity ( < 2). Furthermore, later bottom ice growth during spring warming was observed for SYI in comparison to FYI. The projected increase in the fraction of more permeable FYI in autumn and spring in the coming decades may favor gas exchange at the atmosphere-ice interface when sea ice acts as a source relative to the atmosphere. While the areal extent of old ice is decreasing, so is its thickness at the onset of freeze-up. Our study sets the foundation for studies on gas dynamics within the ice column and the gas exchange at both ice interfaces, i.e. with the atmosphere and the ocean.
1. Recent empirical studies have quantified correlation between survival and recovery by estimating these parameters as correlated random effects with Bayesian multivariate mixed effects models fit to tag-recovery data. In these applications, increasingly negative correlation between survival and recovery indicates increasingly additive harvest mortality. The power of mixed effects models to detect non-zero correlations has rarely been evaluated and these few studies have not focused on a common data type in the form of tag recoveries. 2. We assessed the power of multivariate mixed effects models to estimate negative correlation between annual survival and recovery. Using three priors for multivariate normal distributions, we fit mixed effects models to a mallard (Anas platyrhychos) tag-recovery dataset and to simulated data with sample sizes corresponding to different levels of monitoring intensity. We also demonstrate a method of calculating effective sample size for capture-recapture data. 3) Different priors lead to different inference about additive harvest when we fit our models to the mallard data. Our power analysis of simulated data indicated most prior distribution and sample size combinations resulted in correlation estimates with substantial bias and imprecision. Many correlation estimates spanned the available parameter space (–1,1) and were biased towards zero. Only one prior combined with our most intensive monitoring scenario allowed our models to consistently recover negative correlation without bias. Underestimating the magnitude of correlation coincided with overestimating the variability of annual survival, but not annual recovery. 4) The inadequacy of prior distributions and sample size combinations typically assumed adequate for robust inference represents a concern in the application of Bayesian mixed effects models for the purpose of informing harvest management. Our analysis approach provides a means for examining prior influence and sample size on mixed-effects models fit to capture-recapture data while emphasizing transferability of results between empirical and simulation studies.
An electrostatic voltage is formed in the proposed thermocouple by the induced electrostatic potentials at the metallurgical junctions created by the n - and the p -type legs and their semiconductor emitters that are embedded on their exterior surfaces. The usable range of the electrostatic voltage was defined and used to enhance the output power and the efficiency of the thermocouple. An analytical formulation for and the numerical simulation of the thermocouple showed that the electrostatic voltage, as an addition to the Seebeck voltage, could enhance the output power and the efficiency up to four times those of the original thermocouple design with the same leg doping densities. Furthermore, the numerical simulation showed that for a given n - and a given p -type leg doping densities, an optimal combination of the emitter doping densities could always be found so that the output power and the efficiency of the thermocouple could be enhanced up to four times those of the thermocouple without the emitters.
Background The Children's Healthy Living study provided dietary intake information for understudied Native Hawaiian and Other Pacific Islander (NHOPI) young children. Objectives To describe food group and macronutrient intakes of NHOPI children in the US-affiliated Pacific region (USAP), overall and by jurisdiction, income level, and metabolic status. Methods 2-8 year olds (n = 3520), were evaluated in a cross-sectional cluster sampled study using two days of dietary records completed by caregivers using provided tools, quantified by a specially developed food composition table and compared to US dietary recommendations. Overweight and obesity (OWOB) and acanthosis nigricans (AN) assessment (metabolic status) was completed by trained evaluators using standard tools. Demographic data were collected by questionnaire. Regression analysis identified differences in dietary component means by jurisdiction, World Bank income groups (WBIG) and metabolic status, adjusted for age and sex. Results Few children met US recommendations for vegetable (2.4%) and milk (4.1%) food groups. US macronutrient recommendations were generally met. Food group and macronutrient intakes were significantly different by jurisdiction and WBIG. Means for food groups, except meats, and macronutrients, except protein, were higher among overweight/obese (OWOB) compared to healthy weight children. Grain intake of 7.25 (SE: 0.08) oz was higher (P<0.05) and milk intake of 0.90 (SE: 0.05) cups was lower (P<0.05) among children with OWOB compared to those without OWOB (grains: 7.17 [SE: 0.07] oz and milk: 0.96 [SE: 0.04] cups). Monounsaturated fat intake of 11.68 (SE: 0.10) % energy was higher among those with OWOB, compared to healthy weight children (11.56 [SE: 0.08] % energy, P<0.05). Conclusions Young children's diets in the USAP did not meet milk, vegetable or fruit intake recommendations. There was variability in dietary patterns across the USAP and by WBIG. Grain intake and monounsaturated fat intake was lower and milk intake was higher in children with better metabolic status.
Cycling of organic carbon in the ocean has the potential to mitigate or exacerbate global climate change, but major questions remain about the environmental controls on organic carbon flux in the coastal zone. Here, we used a field experiment distributed across 28° of latitude, and the entire range of 2 dominant kelp species in the northern hemisphere, to measure decomposition rates of kelp detritus on the seafloor in relation to local environmental factors. Detritus decomposition in both species were strongly related to ocean temperature and initial carbon content, with higher rates of biomass loss at lower latitudes with warmer temperatures. Our experiment showed slow overall decomposition and turnover of kelp detritus and modeling of coastal residence times at our study sites revealed that a significant portion of this production can remain intact long enough to reach deep marine sinks. The results suggest that decomposition of these kelp species could accelerate with ocean warming and that low-latitude kelp forests could experience the greatest increase in remineralization with a 9% to 42% reduced potential for transport to long-term ocean sinks under short-term (RCP4.5) and long-term (RCP8.5) warming scenarios. However, slow decomposition at high latitudes, where kelp abundance is predicted to expand, indicates potential for increasing kelp-carbon sinks in cooler (northern) regions. Our findings reveal an important latitudinal gradient in coastal ecosystem function that provides an improved capacity to predict the implications of ocean warming on carbon cycling. Broad-scale patterns in organic carbon decomposition revealed here can be used to identify hotspots of carbon sequestration potential and resolve relationships between carbon cycling processes and ocean climate at a global scale.
The profound impacts that maternal provisioning of finite energy resources has on offspring survival have been extensively studied across mammals. This study shows that in addition to calories, high hemoprotein concentrations in diving mammals necessitates exceptional female-to-pup iron transfer. Numerous indices of iron mobilization (ferritin, serum iron, total-iron-binding-capacity, transferrin saturation) were significantly elevated during lactation in adult female Weddell seals (Leptonychotes weddellii), but not in skip-breeders. Iron was mobilized from endogenous stores for incorporation into the Weddell seal’s milk at concentrations up to 100× higher than terrestrial mammals. Such high rates of iron offload to offspring drew from the female’s own heme stores and led to compromised physiologic dive capacities (hemoglobin, myoglobin, and total body oxygen stores) after weaning their pups, which was further reflected in shorter dive durations. We demonstrate that lactational iron transfer shapes physiologic dive thresholds, identifying a cost of reproduction to a marine mammal.
The complete genome of Erysipelothrix sp. strain Poltava, isolated from fatal acute septic erysipelas of swine in Ukraine, was assembled using Nanopore sequences. One circular chromosome of 1,794,858 bp ( N 50 , 1,794,858 bp) encodes 16 putative antibiotic resistance genes and secreted virulence factors, highlighting the risk of cross-species livestock and human infection.
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2,285 members
Randi Jandt
  • International Arctic Research Center
Wilford Frank Weeks
  • Geophysical Institute
Anne M. Jensen
  • Department of Anthropology
Dirk Lummerzheim
  • Geophysical Institute
Lawrence Duffy
  • Department of Chemistry and Biochemistry
1731 South Chandalar Drive, 99775, Fairbanks, Alaska, United States
Head of institution
Chancellor Dan White; Vice Chancellor for Research Larry Hinzman