University of Nebraska at Lincoln
  • Lincoln, Nebraska, United States
Recent publications
Although automatic impact hammers are often used in dynamics and vibration research, they are seldom if ever used in resource-constrained environments such as undergraduate labs or in emerging nations. The cost of a commercially available automatic modal hammer, which typically costs more than USD 10,000, is the primary reason for the technology’s limited adoption. An inexpensive, automatic modal hammer could thus be useful in educational labs for studying dynamical systems. The goal of this research is to develop a low-cost, repeatable, and scalable automatic modal hammer. The study’s primary goal is to develop and test an open-source modal hammer for studying dynamical systems, including the ones which are strongly nonlinear. A standard modal hammer is mounted on the shaft of a stepper motor, with an encoder controlled by a hybrid servo drive and a microcontroller. The combination of the motor, servo drive, and encoder allows for micro-stepping and precise control of the motor shaft, and thus the motion of the modal hammer. The stepper motors used in this hammer are similar to those found in small 3D printers and CNC machines and are thus widely available and inexpensive. An airplane wing model with a non-smooth nonlinear vibration absorber is used to demonstrate the automatic hammer’s functionality.
Social anxiety disorder is common among emerging adults and is associated with serious functional impairment. Cognitive-behavioral therapy (CBT) is an effective intervention for social anxiety. An online version may increase access but low completion rates limit utility. This study investigated a self-guided, internet based CBT (ICBT) with peer coach support. Participants were 35 undergraduate students randomized for immediate treatment (IT) or wait-list control (WL) in a randomized controlled trial design. IT participants completed a six-week ICBT program on their own and met briefly with a minimally trained undergraduate student as a “coach” between each lesson. IT participants had a greater decline in social anxiety relative to WL participants. High treatment retention and satisfaction ratings demonstrate the acceptability of this online intervention with peer coach support. The higher than expected enrollment from international students suggests ICBT may serve hard-to-reach college populations. This model of care could augment traditional mental health services to expand the availability of care.
Ivermectin is widely used in both animals and humans as an FDA-approved parasiticide. Ivermectin has also been reported to have antiviral activity against several viruses including coronaviruses. There are reports that indicate ivermectin may have some role in diminishing the disease caused by SARS-CoV-2, but the evidence is inconclusive. The objective of this study was to determine if ivermectin was efficacious in inhibiting avian infectious bronchitis virus (IBV, a coronavirus) replication in chicken embryos. Briefly, our approach was to use the Massachusetts vaccine strain of IBV in combination with various doses of ivermectin and then inoculate these preparations into chicken embryos to determine if IBV replication was inhibited. The embryos were examined for IBV lesions and samples of chorioallantoic fluid were collected for IBV RT-PCR analysis. Several trials were performed, and the results of our study indicate that ivermectin did not inhibit IBV replication in chicken embryos.
Predicting phenotype from genotype is a central challenge in biology. By understanding genomic information to predict and improve traits, scientists can address the challenges and opportunities of achieving sustainable genetic improvement of complex, economically important traits in agriculturally relevant species. Converting the enormous, recent technical advances in all areas of genomics and phenomics into sustained and ecologically responsible improvements in food and fuel production is complex. It will require engaging agricultural genome to phenome (G2P) experts, drawing from a broad community, including crop and livestock scientists and essential integrative disciplines (e.g., engineers, economists, data and social scientists). To achieve this vision, the USDA NIFA-funded project inaugurating the Agricultural Genome to Phenome Initiative (AG2PI) is working to: Develop a cohesive vision for agricultural G2P research by identifying research gaps and opportunities; advancing community solutions to these challenges and gaps; and rapidly disseminating findings to the broader community. Towards these ends, this AG2PI project is organizing virtual field days, conferences, training workshops, and awarding seed grants to conceive new insights (details at www.ag2pi.org). Since October 2020, more than 10,000 unique participants from every inhabited continent have engaged in these activities. To illustrate AG2PI’s scope, we present survey results on agricultural G2P research needs and opportunities, highlighting opinions and suggestions for the future. We invite stakeholders interested in this complex but critical effort to help create an optimal, sustainable food supply for society and challenge the community to add to our vision for future accomplishments by a fully actualized AG2PI enterprise.
Christoph Ransmayr's novels are known for complex interactions with time and the reimaging of historical events. This article considers the function of historical imagination in Cox oder der Lauf der Zeit (2016). The novel's fictional transposition to China of an eighteenth‐century quest for perpetual motion serves to link the control of time to the unprecedented worldly power of the Chinese emperor, but also to the decline of that power vis‐à‐vis the rise of industrial capitalism. The novel layers together the histories of perpetual motion and renewable energy, connecting both to emergent human geological agency. By framing this agency as the expression of the power of a few individuals, the novel opens spaces in which we can imagine a kind of thinking that might confront the constraints placed upon all of humanity by the actions of small groups in the past.
With the rapid growth of electric vehicles (EVs) in the past decade, many new traffic safety challenges are also emerging. With the crash data of Norway from 2011 to 2018, this study gives an overview of the status quo of EV crashes. In the survey period, the proportion of EV crashes in total traffic crashes had risen from zero to 3.11% in Norway. However, in terms of severity, EV crashes do not show statistically significant differences from the Internal Combustion Engine Vehicle (ICEV) crashes. Compared to ICEV crashes, the occurrence of EV crashes features on weekday peak hours, urban areas, roadway junctions, low-speed roadways, and good visibility scenarios, which can be attributed to the fact that EVs are mainly used for urban local commuting travels in Norway. Besides, EVs are confirmed to be much more likely to collide with cyclists and pedestrians, probably due to their low-noise engines. Then, the separate logistic regression models are built to identify important factors influencing the severity of ICEV and EV crashes, respectively. Many factors show very different effects on ICEV and EV crashes, which implies the necessity of re-evaluating many current traffic safety strategies in the face of the EV era. Although the Norway data is analyzed here, the findings are expected to provide new insights to other countries also in the process of the complete automotive electrification.
The solar spectrum energy absorption is very important for designing any solar absorber. The need for absorbing visible, infrared, and ultraviolet regions is increasing as most of the absorbers absorb visible regions. We propose a metasurface solar absorber based on Ge2Sb2Te5 (GST) substrate which increases the absorption in visible, infrared and ultraviolet regions. GST is a phase-changing material having two different phases amorphous (aGST) and crystalline (cGST). The absorber is also analyzed using machine learning algorithm to predict the absorption values for different wavelengths. The solar absorber is showing an ultra-broadband response covering a 0.2–1.5 µm wavelength. The absorption analysis for ultra-violet, visible, and near-infrared regions for aGST and cGST is presented. The absorption of aGST design is better compared to cGST design. Furthermore, the design is showing polarization insensitiveness. Experiments are performed to check the K-Nearest Neighbors (KNN)-Regressor model’s prediction efficiency for predicting missing/intermediate wavelengths values of absorption. Different values of K and test scenarios; C-30, C-50 are used to evaluate regressor models using adjusted R² Score as an evaluation metric. It is detected from the experimental results that, high prediction proficiency (more than 0.9 adjusted R² score) can be accomplished using a lower value of K in KNN-Regressor model. The design results are optimized for geometrical parameters like substrate thickness, metasurface thickness, and ground plane thickness. The proposed metasurface solar absorber is absorbing ultraviolet, visible, and near-infrared regions which will be used in solar thermal energy applications.
A sensitive Enzyme-linked Immunosorbent Assay (ELISA) with improved broad species specificity was developed for the detection of southern hemisphere fish residues in processed foods. The polyclonal antibodies were raised against parvalbumins from 13 fish species representing 7 fish orders selected for their molecular diversity and immunoreactivity profile. The optimized ELISA-2 (based on the rabbit capture antibody (RB#4) - sheep detection antibody (S2#4) pair) displayed an improved detection limit of 0.6 μg/L (3.7 μg of /kg). Our immunoreactivity-directed species selection approach in the strategized antibody production significantly improved the detection of no or weakly immunoreactive fish species previously not detected immunochemically. Of 37 commercially important fish species tested, the ELISA-2 could detect 28 fish species (76%). The optimized sample extraction with a buffer additive achieved good protein recoveries of 87.2 – 117.3% (within the AOAC recommended range). The ELISA-2 was able to detect fish residues in five highly processed food products.
This study was conducted to investigate the impact of intermittent feeding on performance, clogging, and gaseous emission on macrophyte assisted vermifiltration (MAVF) based treatment system. Synthetic slaughterhouse wastewater was applied to two different integrated vertical flow based MAVFs. Triplicates were used throughout the study. Eisenia fetida earthworms were added to MAVFs, and Carex muskingmenis plants were planted. Wastewater was applied to the reactors on 1) intermittent (8 h/day) (IMAVF) and 2) continuous (24 h/day) (CMAVF) basis. The average chemical oxygen demand, total nitrogen, and total phosphorous removals achieved by the IMAVF were 80.2 ± 1.6%, 53.9 ± 1.3% and 66.5 ± 1% respectively, and 68.3 ± 1.3%, 61.2 ± 1.4%, and 60.5 ± 1.4% by the CMAVF, respectively. The diffusion of air to the bedding of IMAVFs during no-flow conditions facilitated higher organics oxidation, adsorption of phosphorous, nitrification, and ammonification. At the end of the study, hydraulic conductivity of IMAVF and CMAVF were found to be 0.036 cm/s and 0.037 cm/s, respectively. CO 2 , CH 4 and N 2 O emissions from IMAVF were 245.5 ± 38.0 mg C/m ² , 5.0 ± 4.6 mg C/m ² and 2513.5 ± 2629.9 μg N/m ² respectively, while CO 2 , CH 4 and N 2 O emissions from CMAVF were 123.3 ± 14.5 mg C/m ² , 74.8±45.2 mg C/m ² and 328.4 ± 93.4 μg N/m ² , respectively. Intermittent application of influent could be considered for improving the performance and lifespan of MAVFs, causing lower environmental footprints.
The integration of dissimilar materials into heterostructures has become a powerful tool for engineering interfaces and electronic structure. The advent of 2D materials has provided unprecedented opportunities for novel heterostructures in the form of van der Waals stacks, laterally stitched 2D layers and more complex layered and 3D architectures. This Primer provides an overview of state-of-the-art methodologies for producing such van der Waals heterostructures, focusing on the two fundamentally different strategies, top-down deterministic assembly and bottom-up synthesis. Successful techniques, advantages and limitations are discussed for both approaches. As important as the fabrication itself is the characterization of the resulting engineered materials, for which a range of analysis techniques covering structure, composition and emerging functionality are highlighted. Examples of the properties of artificial van der Waals structures include optoelectronics and plasmonics, twistronics and unique functionality arising from the generalization of van der Waals assembly from 2D to 3D crystalline components. Finally, current issues of reproducibility, limitations and opportunities for future breakthroughs in terms of enhanced homogeneity, interfacial purity, feature control and ultimately orders-of-magnitude increased complexity of van der Waals heterostructures are discussed. Van der Waals epitaxy provides numerous opportunities for materials integration in heterostructures. This Primer provides an overview of methodologies for producing van der Waals heterostructures, focusing on top-down assembly and bottom-up synthesis, and discusses future opportunities for their continued development.
Molecular dynamics simulations reveal slip transmutation mechanisms between basal 〈a〉 dislocations and {112¯1} twinning in titanium. When a co-planar pileup of basal 〈a〉 dislocations approaches (112¯4) coherent twin boundary (CTB), the 1st dislocation transmutes into a four-layer (112¯1) twin in the (112¯4) twin, forming a (112¯4)−(112¯1) double twin, and the 2nd and 3rd dislocations climb along the (112¯4) CTB and then transmute into twinning dislocations, thickening the (112¯1) secondary twin. When the (112¯1) secondary twin propagates and encounters the other (112¯4) CTB, a reverse transmutation happens associated with the nucleation and emission of partial dislocations.
How no-till management affects soil-profile compactibility in the long-term is unknown. The few previous studies measured soil compactibility for the upper 20 cm soil depth, which limits a complete understanding of the potential changes in compactibility for deeper depths. The objective of this study was to determine Proctor bulk density at different soil water contents, Proctor maximum bulk density (MaxBD), water content at MaxBD termed as critical water content (CWC), and relationships of MaxBD and CWC with soil organic C (SOC) and mean weight diameter of water-stable aggregates (MWD) for the 0–15, 15–30, and 30–60 cm depths in two long-term (32 and 36 yr) tillage experiments in the western US Corn Belt on silty clay loam soils. Treatments were: moldboard plow, disk, and no-till under continuous corn (Zea mays L.) and corn-soybean (Glycine max L.) rotation at the 32-yr site, and moldboard plow, chisel plow, double disk, and no-till under corn-soybean rotation at the 36-yr site. No-till reduced Proctor bulk density and MaxBD only at the 32-yr site and shallow depth (0–15 cm) by 5% compared with moldboard plow. However, disking reduced Proctor bulk density compared with plowed systems to 60 cm depth at the 32-yr site and to 30 cm depth at the 36-yr site. Disking at both sites reduced MaxBD by 7% (0.10 Mg m⁻³) to 30 cm depth compared with plowed treatments. Compared with moldboard plow, disk till increased CWC by 3% for the 30–60 cm depth at the 32-yr site, while both disk and no-till increased CWC by 5% at the 0–15 cm depth at the 36-yr site. Maximum compactibility decreased as SOC concentration and MWD increased, while CWC increased as SOC concentration increased at most soil depths. No-till reduces soil compactibility only near the surface compared with plowed systems but reduced till (disk) reduces compactibility to deeper depths in the profile, suggesting it can be more effective than no-till at reducing compactibility.
Emerging research suggests that trait neuroticism is associated with enhanced attention to and perception of negative emotional stimuli, increasing the risk for multiple forms of psychopathology including depression and anxiety. However, modifiable factors such as certain forms of emotion regulation have the potential to weaken this association. In a large sample (N = 1252), we investigated the link between neuroticism and valence bias in response to stimuli that have the potential for both positive and negative interpretations and examined the moderating role of interpersonal emotion regulation. Primary tests of hypotheses demonstrated that increased neuroticism was associated with a more negative valence bias in response to ambiguity, but only for individuals who are less likely to rely on interpersonal resources to regulate negative affect. Supplemental analyses suggest that this moderation effect of interpersonal emotion regulation might depend on the nature of the stimuli, and that regulation of positive emotions—not just negative affect—can also contribute to a less negative valence bias. Taken together, results suggest that individuals who are high in neuroticism, but consistently rely on interpersonal relationships to regulate their emotions, are better able to override the bias toward negativity that can occur when appraising ambiguity.
Red snow algal blooms reduce albedo and increase snowmelt, but little is known of their extent, duration, and radiative forcing. We calibrated an established index by comparing snow algal field spectroradiometer measurements with direct counts of algal cell abundance in British Columbia, Canada. We applied the field calibrated index to Sentinel-2, Landsat-8, and MODIS/Terra images to monitor snow algae on the Vowell and Catamount Glaciers (Purcells, British Columbia) in summer 2020. The maximum extent of snow algal bloom cover was 1.4 and 2.0 km² respectively, about one third of the total surface area of the two glaciers, making these among the largest contiguous bloom areas yet reported. Blooms were first detected following the onset of above-freezing temperatures in early July and persisted for about two months. Algal abundance increased through July, after which the red snow algal bloom area decreased due to snow cover loss. At their peak in late July the blooms reduced albedo by 0.04 ± 0.01 on average. Snow algae caused an additional 5.25 ± 1.0 × 10⁷ J/m² of solar energy to be absorbed by the snowpack in July–August, which is enough energy to melt 31.5 cm of snow. This is equivalent to an average snow algal radiative forcing of 8.25 ± 1.6 W/m² through July and August. Our results suggest that the extent, duration, and radiative forcing of snow algal blooms are sufficient to enhance glacial melt rates.
The relationship between biodiversity and spectral diversity is highly scale-dependent, and temporal variation in leaf morphological, biochemical traits and canopy structure can alter this relationship. However, the temporal dependence of the spectral diversity – biodiversity relationship is poorly understood, in part due to the difficulties of obtaining consistent measurements across space and time. Using leaf pigments and leaf and canopy reflectance throughout a growing season in the Cedar Creek prairie biodiversity experiment, we explored phenological effects on the scale dependence of the spectral biodiversity – biodiversity relationship. Leaf reflectance spectra displayed larger among-species variation than leaf pigments, indicating that leaf reflectance contained more information for distinguishing species than some leaf trait measurements. At the canopy scale, spectral variation derived using reflectance was mainly driven by among-species variation. The canopy scale spectral diversity was also influenced by changing vegetation percent cover, key phenological events (e.g., flowering), and disturbance (drought). Our results revealed that contrasting phenological patterns of spectral diversity metrics emerged at leaf and canopy scales. Because a misunderstanding of these contrasting temporal effects across spatial scales can lead to possible misinterpretations of the spectral diversity – biodiversity relationship or of their underlying causes, more research effort is needed to understand these cross-scale temporal effects.
Irrigation has traditionally been managed as uniform applications where an entire field receives the same depth of water. Motivation to improve current irrigation practices has led to different approaches utilizing remotely-sensed images to inform variable rate irrigation management. This study conducted in 2019 and 2020 implemented the Spatial EvapoTranspiration Modeling Interface (SETMI), a remote-sensing-based evapotranspiration (ET) and water balance model, for managing variable rate irrigation of a maize and soybean field. This model tracked soil water content through the estimation of daily ET and tracking of various water fluxes entering and leaving a field. SETMI was used in two different irrigation treatments informed using Planet satellite (SETMI-SAT) and unmanned aerial system (UAS, SETMI-UAS) remotely-sensed images. A uniform irrigation approach managed by a professional crop consultant and a non-irrigated approach were used as the baseline in comparing irrigation management approaches. The irrigation treatments were evaluated on dry grain yield, gross irrigation, actual ET, deep percolation, change in soil water content, and water productivity. The uniform irrigation approach managed by the crop consultant applied the highest irrigation in 2019 and 2020 for maize (2019: 155 mm, 2020: 213 mm) and soybean (2019: 124 mm; 2020: 183 mm) while the SETMI irrigation treatments applied less irrigation for maize (2019: 131, 132 mm; 2020: 154, 140 mm) and soybean (2019: 116, 94 mm; 2020: 154, 175 mm). Maize yield was highest for the uniform irrigation approach in 2019 (14.9 Mg ha⁻¹) and 2020 (13.3 Mg ha⁻¹). The highest soybean yield was produced by the SETMI-SAT irrigation management approach in 2019 (5.0 Mg ha⁻¹) and 2020 (4.8 Mg ha⁻¹). Significant differences (p-value < 0.05) in applied irrigation between the uniform and SETMI irrigation management approaches were observed while there were no significant differences in dry grain yield for both maize and soybean in 2019 and 2020. At least one of the SETMI irrigation treatments produced higher crop, irrigation, and ET water productivity values in comparison to those produced by the uniform irrigation treatment for all crop-years. A post-season analysis was completed using the SETMI-UAS and SETMI-SAT treatments to evaluate the accuracy of estimated rootzone soil water depletion provided by SETMI. Rootzone depletion calculated from neutron probe volumetric soil water content measurements were compared to the modeled depletion from the SETMI-UAS and SETMI-SAT treatments. The 2020 modeled and measured depletion comparison produced better agreement resulting in a root mean squared error (RMSE) < 17 mm compared to 2019 (RMSE < 27 mm). The VRI center pivot malfunctioned during the 2019 season which caused unresolved discrepancies between actually applied irrigation and what the system was programmed to apply. The VRI system was fixed before the 2020 season.
Binary transgender and nonbinary people face interpersonal and societal discrimination which can contribute to minority stress and negative mental health. Thus, it is important that family therapists understand what factors contribute to psychological well-being to be able to offer helpful and inclusive therapy services to these communities. This study addresses a gap in the literature regarding differences in factors contributing to psychological well-being between binary transgender and nonbinary people as well as understanding these factors in a predominantly People of Color (POC) sample. Utilizing secondary data from the Social Justice Sexuality Project (Battle and DeFreece in Women Gend Fam Color 2(1):1–31. https://doi.org/10.5406/womgenfamcol.2.1.0001, 2014; Battle et al. in Social justice sexuality survey: cumulative codebook, City University of New York-Graduate Center, New York, 2012), this study examined the relationships between perceived family support, religiosity, community connectedness and psychological well-being in a sample of binary transgender and nonbinary people. Results from a multiple group path analysis show that perceived family support, religiosity and being connected to an LGBT community were significantly associated with psychological well-being for binary transgender people, while only LGBT community connectedness was significantly associated with psychological well-being for nonbinary people. Implications for family therapists include helping families support binary transgender and nonbinary family members, deconstructing non-affirming religious messages about gender identity and connecting clients to affirmative religions and religious leaders, and being knowledgeable about community resources for binary transgender and nonbinary POC.
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7,152 members
J. D. Burton
  • Department of Physics and Astronomy
Tsegaye Tadesse
  • National Drought Mitigation Center
Jon E Pedersen
  • Department of Teaching, Learning and Teacher Education
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1400 R St, 68588, Lincoln, Nebraska, United States
Head of institution
Dr. Ronnie Green
Website
http://www.unl.edu/