Digital Commons Network^™

Interaction With Augmented Reality Sandbox Does Not Produce Greater Gains In Topographic Map Skills For Undergraduate Students, Celeste Kenworthy

Honors Program: Senior Projects (Public)

The augmented reality (AR) sandbox allows students to interact with topographic maps in a 3D space. Being able to understand topographic maps is important to geologists and they are taught in many introductory geology courses. Recent research has focused on whether the AR sandbox can improve students’ topographic map skills. Previous studies have found that students who interact with the AR sandbox do not score significantly better on topographic map assessments (TMAs) than their peers. One proposed reason for this is the limited time students have to interact with the AR sandbox. This study sought to address this by creating …

Replicating Or Franchising A Stem Afterschool Program Model: Core Elements Of Programmatic Integrity, Nikolaus Stevenson, Amie S. Sommers, Neal Grandgenett, William Tapprich, Julia Mcquillan, Michelle Phillips, Rachael Jensen, Christine Cutucache

Department of Sociology: Faculty Publications

Background: Designed in 2012 with a first implementation in 2013, NE STEM 4U is a professional development program for post-secondary students/undergraduates, and serves as a source of outreach, content knowledge generation, and STEM literacy for youth in grades kindergarten through 8th grade (ages 5–14). The model empowers post-secondary students as facilitators of inquiry-based learning within the context of an out-of-school time program. This study investigated the potential for replicating or ‘franchising’ this model by evaluating on the following: (1) Is the model replicable? And, if so, (2) what core elements are necessary for program fidelity? And (3) is there …

Electronic Reconstruction At The Polar (111)-Oriented Oxide Interface, S. Ryu, H. Zhou, Tula R. Paudel, Neil Campbell, J. Podkaminer, C. W. Bark, T. Hernandez, D. D. Fong, Y. Zhang, L. Xie, X. Q. Pan, Evgeny Y. Tsymbal, M. S. Rzchowski, Chang-Beom Eom

Evgeny Tsymbal Publications

Atomically flat (111) interfaces between insulating perovskite oxides provide a landscape for new electronic phenomena. For example, the graphene-like coordination between interfacial metallic ion layer pairs can lead to topologically protected states [Xiao et al., Nat. Commun. 2, 596 (2011) and A. Rüegg and G. A. Fiete, Phys. Rev. B 84, 201103 (2011)]. The metallic ion/metal oxide bilayers that comprise the unit cell of the perovskite (111) heterostructures require the interface to be polar, generating an intrinsic polar discontinuity [Chakhalian et al., Nat. Mater. 11, 92 (2012)]. Here, we investigate epitaxial heterostructures of (111)-oriented LaAlO₃/SrTiO₃ (LAO/STO). We …

A Pivotal New Approach To Groundwater Quality Assessment, M. L. Cherry, T. Gilmore, T. Messer, Y. Li, J. Westrop

School of Natural Resources: Faculty Publications

No abstract provided.

Plague Risk In The Western United States Over Seven Decades Of Environmental Change, Colin J. Carlson, Sarah N. Bevins, Boris V. Schmid

United States Department of Agriculture Wildlife Services: Staff Publications

After several pandemics over the last two millennia, the wildlife reservoirs of plague (Yersinia pestis) now persist around the world, including in the western United States. Routine surveillance in this region has generated comprehensive records of human cases and animal seroprevalence, creating a unique opportunity to test how plague reservoirs are responding to environmental change. Here, we test whether animal and human data suggest that plague reservoirs and spillover risk have shifted since 1950. To do so, we develop a new method for detecting the impact of climate change on infectious disease distributions, capable of disentangling long-term trends (signal) and …

Wild Pig Removal Reduces Pathogenic Bacteria In Low-Order Streams, Sara A. Bolds, B. Graeme Lockaby, Latif Kalin, Stephen S. Ditchkoff, Mark D. Smith, Kurt Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Invasive wild pig populations have undergone enormous increases in the United States and particularly across the southern U.S. in recent years. High fecundity rates and abilities to adapt quickly to varied habitats have enabled pig populations to become entrenched and difficult to eliminate. The pigs cause many negative impacts on ecosystems including degradation of water quality through infusion of fecal contamination and other non-point source pollutants. Our goal was to determine the effects of pig removal on water quality in streams that were known to be significantly polluted by pig activity Bolds (J Environ Qual 50: 441–453, 2021). We compared …

A Model For Leveraging Animal Movement To Understand Spatio-Temporal Disease Dynamics, Mark Q. Wilber, Anni Yang, Raoul Boughton, Kezia R. Manlove, Ryan S. Miller, Kim M. Pepin, George Wittemyer

United States Department of Agriculture Wildlife Services: Staff Publications

The ongoing explosion of fine-resolution movement data in animal systems provides a unique opportunity to empirically quantify spatial, temporal and individual variation in transmission risk and improve our ability to forecast disease outbreaks. However, we lack a generalizable model that can leverage movement data to quantify transmission risk and how it affects pathogen invasion and persistence on heterogeneous landscapes. We developed a flexible model ‘Movement-driven modelling of spatio-temporal infection risk’ (MoveSTIR) that leverages diverse data on animal movement to derive metrics of direct and indirect contact by decomposing transmission into constituent processes of contact formation and duration and pathogen deposition …

Transverse Oscillating Bubble Enhanced Laser‑Driven Betatron X‑Ray Radiation Generation, Rafal Rakowski, Ping Zhang, Kyle Jensen, Brendan Kettle, Tim Kawamoto, Sudeep Banerjee, Colton Fruhling, Grigory Golovin, Daniel Haden, Matthew S. Robinson, Donald Umstadter, Bradley A. Shadwick, Matthias Fuchs

Department of Physics and Astronomy: Faculty Publications

Ultrafast high-brightness X-ray pulses have proven invaluable for a broad range of research. Such pulses are typically generated via synchrotron emission from relativistic electron bunches using large-scale facilities. Recently, significantly more compact X-ray sources based on laser-wakefield accelerated (LWFA) electron beams have been demonstrated. In particular, laser-driven sources, where the radiation is generated by transverse oscillations of electrons within the plasma accelerator structure (so-called betatron oscillations) can generate highly-brilliant ultrashort X-ray pulses using a comparably simple setup. Here, we experimentally demonstrate a method to markedly enhance the parameters of LWFA-driven betatron X-ray emission in a proof-of-principle experiment. We show a …

Spin Hall Effect Of Vorticity, Edward Schwartz, Hamed Vakili, Moaz Ali, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

Using mapping between topological defects in an easy-plane magnet and electrical charges, we study interplay between vorticity and spin currents. We demonstrate that the flow of vorticity is accompanied by the transverse spin current generation; an effect which can be termed as the spin Hall effect of vorticity. We study this effect across the BKT transition and establish the role of dissipation and spin nonconservation in the crossover from spin superfluidity to diffusive spin transport. Our results pave the way for low power computing devices relying on vorticity and spin flows that can propagate over long distances.

Superfluid Spin Transistor, Edward Schwartz, Bo Li, Alexey Kovalev

Alexey Kovalev Papers

We propose to use the Hall response of topological defects, such as merons and antimerons, to spin currents in two-dimensional magnetic insulator with in-plane anisotropy for identification of the Berezinskii-Kosterlitz-Thouless (BKT) transition in a transistorlike geometry. Our numerical results relying on a combination of Monte Carlo and spin dynamics simulations show transition from spin superfluidity to conventional spin transport, accompanied by the universal jump of the spin stiffness and exponential growth of the transverse vorticity current. We propose a superfluid spin transistor in which the spin and vorticity currents are modulated by changes in density of free topological defects, e.g., …

Second Twenty-Five Year Index: Volumes 26–50, 1994–2018, Jane E. Austin

The Prairie Naturalist

The first 50 years of the Prairie Naturalist reside on the shelves of libraries and personal collections. The articles and notes published over those years provide invaluable knowledge about Great Plains biota, communities, conservation, and landscape ecologies. Awareness of the wealth of information in those 50 print volumes has been limited, relying on references from other published papers or the limited number of articles that have been made available online by authors. This index serves as resource for individuals to digitally tap into the information published since 1994. This index, together with the first 25-year index, serves to complement the …

Review Of Loon Lessons: Uncommon Encounters With The Great Northern Diver, By James D. Paruk, Kristin Bianchini

The Prairie Naturalist

Gavia immer Brunnich (Common Loon) is a bird that has captivated bird watchers, wildlife enthusiasts, campers, cottagers, and others interested in the natural world for centuries. The loon also features prominently in Native American mythology. For many, the loon symbolizes the wildness of the north, and it is often used as a sentinel of lake health. Indeed, the Common Loon has inspired a wealth of literature, both scientific and popular, describing this species’ ecology, behavior, and fitness in the face of environmental changes. To this literature, Loon Lessons: Uncommon Encounters with the Great Northern Diver adds a complete and accurate …

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In This Issue

Infrared Dielectric Functions And Brillouin Zone Center Phonons Of Α-Ga2O3 Compared To Α-Al2O3, Megan Stokey, Rafal Korlacki, Matthew J. Hilfiker, Sean Knight, Steffen Richter, Vanya Darakchieva, Riena Jinno, Yongjin Cho, Huili Grace Xing, Debdeep Jena, Yuichi Oshima, Kamruzzaman Khan, Elaheh Ahmadi, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

We determine the anisotropic dielectric functions of rhombohedral α-Ga₂O₃ by far-infrared and infrared generalized spectroscopic ellipsometry and derive all transverse optical and longitudinal optical phonon mode frequencies and broadening parameters. We also determine the high-frequency and static dielectric constants. We perform density functional theory computations and determine the phonon dispersion for all branches in the Brillouin zone, and we derive all phonon mode parameters at the Brillouin zone center including Raman-active, infrared-active, and silent modes. Excellent agreement is obtained between our experimental and computation results as well as among all previously reported partial information from experiment …

Construction Of A Peridynamic Model For Viscous Flow, Jiangming Zhao, Adam Larios, Florin Bobaru Ph.D.

Department of Mechanical and Materials Engineering: Faculty Publications

We derive the Eulerian formulation for a peridynamic (PD) model of Newtonian viscous flow starting from fundamental principles: conservation of mass and momentum. This formulation is different from models for viscous flow that utilize the so-called “peridynamic differential operator” with the classical Navier- Stokes equations. We show that the classical continuity equation is a limiting case of the PD one, assuming certain smoothness conditions. The PD model for viscous flow is calibrated to the classical Navier-Stokes equations by enforcing linear consistency for the viscous stress term. Couette and Poiseuille flows, and incompressible fluid flow past a regular lattice of cylinders …

Recent Advances In Biosensors For Detection Of Covid-19 And Other Viruses, Shobhit K. Patel, Jaymit Surve, Juveriya Parmar, Kawsar Ahmed, Francis M. Bui, Fahad Ahmed Al-Zahrani

Department of Mechanical and Materials Engineering: Faculty Publications

This century has introduced very deadly, dangerous, and infectious diseases to humankind such as the influenza virus, Ebola virus, Zika virus, and the most infectious SARS-CoV-2 commonly known as COVID-19 and have caused epidemics and pandemics across the globe. For some of these diseases, proper medications, and vaccinations are missing and the early detection of these viruses will be critical to saving the patients. And even the vaccines are available for COVID-19, the new variants of COVID-19 such as Delta, and Omicron are spreading at large. The available virus detection techniques take a long time, are costly, and complex and …

Malaria Resilience In South America: Epidemiology, Vector Biology, And Immunology Insights From The Amazonian International Center Of Excellence In Malaria Research Network In Peru And Brazil, Kathrine Torres, Marcelo U. Ferreira, Marcia C. Castro, Ananias A. Escalante, Jan E. Conn, Elizabeth Villasis, Maisa Da Silva Araujo, Gregorio Almeida, Priscila T. Rodrigues, Rodrigo M. Corder, Anderson R.J. Fernandes, Priscila R. Calil, Winni A. Ladeia, Stefano S. Garcia-Castillo, Joaquin Gomez, Lis Ribeiro Do Valle Antonelli, Ricardo T. Gazzinelli, Douglas T. Golenbock, Alejandro Llanos-Cuentas, Dionicia Gamboa, Joseph M. Vinetz

Harold W. Manter Laboratory of Parasitology: Library Materials

The 1990s saw the rapid reemergence of malaria in Amazonia, where it remains an important public health priority in South America. The Amazonian International Center of Excellence in Malaria Research (ICEMR) was designed to take a multidisciplinary approach toward identifying novel malaria control and elimination strategies. Based on geographically and epidemiologically distinct sites in the Northeastern Peruvian and Western Brazilian Amazon regions, synergistic projects integrate malaria epidemiology, vector biology, and immunology. The Amazonian ICEMR’s overarching goal is to understand how human behavior and other sociodemographic features of human reservoirs of transmission— predominantly asymptomatically parasitemic people—interact with the major Amazonian malaria …

Male Mastodon Landscape Use Changed With Maturation (Late Pleistocene, North America), Joshua H. Miller, Daniel C. Fisher, Brooke E. Crowley, Ross Secord, Bledar A. Konomi

Department of Earth and Atmospheric Sciences: Faculty Publications

Under harsh Pleistocene climates, migration and other forms of seasonally patterned landscape use were likely critical for reproductive success of mastodons (Mammut americanum) and other megafauna. However, little is known about how their geographic ranges and mobility fluctuated seasonally or changed with sexual maturity. We used a spatially explicit movement model that coupled strontium and oxygen isotopes from two serially sampled intervals (5+ adolescent years and 3+ adult years) in a male mastodon tusk to test for changes in landscape use associated with maturation and reproductive phenology. The mastodon’s early adolescent home range was geographically restricted, with no evidence of …

Cloud Radiative Effects On Mjo Development In Dynamo, Qi Hu, Zihang Han, Shuguang Wang

Department of Earth and Atmospheric Sciences: Faculty Publications

Observed Madden–Julian oscillation (MJO) events are examined with the aid of regional model simulations to understand the role of cloud radiative effects in the MJO development. The importance of this role is demonstrated by the absence of the MJO in the model simulations that contain no cloud radiative effects. Comparisons of model simulations with and without the cloud radiative effects and observation help identify the major processes arising from those effects. Those processes develop essentially from heating in the upper troposphere due to shortwave absorption within anvil clouds in the upper troposphere and the convergence of longwave radiation in the …

Recent Advances Toward Transparent Methane Emissions Monitoring: A Review, Broghan M. Erland, Andrew K. Thorpe, John Gamon

Department of Earth and Atmospheric Sciences: Faculty Publications

Given that anthropogenic greenhouse gas (GHG) emissions must be immediately reduced to avoid drastic increases in global temperature, methane emissions have been placed center stage in the fight against climate change. Methane has a significantly larger warming potential than carbon dioxide. A large percentage of methane emissions are in the form of industry emissions, some of which can now be readily identified and mitigated. This review considers recent advances in methane detection that allow accurate and transparent monitoring, which are needed for reducing uncertainty in source attribution and evaluating progress in emissions reductions. A particular focus is on complementary methods …

High Throughput Analysis Of Leaf Chlorophyll Content In Sorghum Using Rgb, Hyperspectral, And Fluorescence Imaging And Sensor Fusion, Huichun Zhang, Yufeng Ge, Xinyan Xie, Abbas Atefi, Nuwan Wijewardane,, Suresh Thapa

School of Computing: Faculty Publications

Leaf chlorophyll content plays an important role in indicating plant stresses and nutrient status. Traditional approaches for the quantification of chlorophyll content mainly include acetone ethanol extraction, spectrophotometry and high-performance liquid chromatography. Such destructive methods based on laboratory procedures are time consuming, expensive, and not suitable for high-throughput analysis. High throughput imaging techniques are now widely used for non-destructive analysis of plant phenotypic traits. In this study three imaging modules (RGB, hyperspectral, and fluorescence imaging) were, separately and in combination, used to estimate chlorophyll content of sorghum plants in a greenhouse environment. Color features, spectral indices, and chlorophyll fluorescence intensity …

Strange Stones Of Skull Creek: Basalt Glacial Erratics And Omars In Eastern Nebraska, Robert M. Joeckel, Jesse T. Korus, Judith Turk, C. C. Arps, N. V. Arps, Leslie M. Howard

Conservation and Survey Division: Faculty and Staff Publications

We describe unusual stream- reworked glacially transported rocks (erratics) from a locality 50 km east of the limit of all pre- Illinoian (pre- 190 ka) Pleistocene glaciations in the central USA. Almost all these erratics consist of the igneous rock basalt, and of those, the vast majority have at least one fl at, smooth face. Some have two or more such faces that meet at obtuse angles along one or more well- defi ned, straight edges. We attribute these features, as well as laminations, plumose marks, and other features, to columnar jointing in ancient lava fl ows and shallow intrusions. …

The Impact Of Sampling Methodology On Soil Bulk Density Measurement By The Clod Method, Aldi J. Airori, Trinity Baker, Judith Turk

Conservation and Survey Division: Faculty and Staff Publications

The clod method is a widely used and accurate bulk density method. However, its use is limited to sampling from soil pits. This study was conducted to: 1) determine whether clods collected from cores provide similar bulk density measurements to those collected from soil pits and 2) evaluate the impact of various clod bulk density methods on carbon stock calculation. Clods were collected from soil pits, 5.1 cm soil cores, and 8.9 cm soil cores. Three-dimensional laser scanning was used to measure the volume of the soil clods before and after oven-drying and bulk density was calculated as the dry …

Mathematics Of Generalized Versions Of The Melitz, Krugman, And Armington Models With Detailed Derivations, Edward J. Balistreri, David G. Tarr

Department of Economics: Faculty Publications

We provide detailed textbook style mathematical derivations of an extended version of the heterogenous firms model of Melitz (2003), as well as the Armington (1969) and Krugman (1980) models. Our model of heterogeneous firms extends the model of Melitz (2003) by allowing multiple sectors, intermediates, heterogeneous regions based on data, labor-leisure choice, initial heterogeneous tariffs, multiple factors of production, the possibility of sector-specific inputs and trade imbalances based on data, and we incorporate global and unilateral tariff policy shocks. Although the models in this paper are extensions in numerous directions of the Melitz trade model of heterogeneous firms, the pedagogical …

Amphibians And Reptiles Of Nebraska Coloring Pages, John Lokke

Conservation and Survey Division: Faculty and Staff Publications

Black and white images from original art by John Lokke. Suitable for coloring pages. Published by the Nebraska Maps & More Store at the School of Natural Resources, University of Nebraska - Lincoln.

Using Deep Learning To Detect Digitally Encoded Dna Trigger For Trojan Malware In Bio‑Cyber Attacks, M. S. Islam, S. Ivanov, H. Awan, J. Drohan, Sasitharan Balasubramaniam, L. Coffey, Srivatsan Kidambi, W. Sri-Saan

School of Computing: Faculty Publications

This article uses Deep Learning technologies to safeguard DNA sequencing against Bio-Cyber attacks. We consider a hybrid attack scenario where the payload is encoded into a DNA sequence to activate a Trojan malware implanted in a software tool used in the sequencing pipeline in order to allow the perpetrators to gain control over the resources used in that pipeline during sequence analysis. The scenario considered in the paper is based on perpetrators submitting synthetically engineered DNA samples that contain digitally encoded IP address and port number of the perpetrator’s machine in the DNA. Genetic analysis of the sample’s DNA will …

Mr-Pipa: An Integrated Multi-Level Rram (Hfox) Based Processing-In-Pixel Accelerator, Minhaz Abedin, Arman Roohi, Maximilian Liehr, Nathaniel Cady, Shaahin Angizi

School of Computing: Faculty Publications

This work paves the way to realize a processing-in-pixel accelerator based on a multi-level HfO_x RRAM as a flexible, energy-efficient, and high-performance solution for real-time and smart image processing at edge devices. The proposed design intrinsically implements and supports a coarse-grained convolution operation in low-bit-width neural networks leveraging a novel compute-pixel with non-volatile weight storage at the sensor side. Our evaluations show that such a design can remarkably reduce the power consumption of data conversion and transmission to an off-chip processor maintaining accuracy compared with the recent in-sensor computing designs. Our proposed design, namely MR-PIPA, achieves a frame rate …

Decision-Theoretic Planning With Communication In Open Multiagent Systems, Anirudh Kakarlapudi, Gayathri Anil, Adam Eck, Prashant Doshi, Leen-Kiat Soh

School of Computing: Faculty Publications

In open multiagent systems, the set of agents operating in the environment changes over time and in ways that are nontrivial to predict. For example, if collaborative robots were tasked with fighting wildfires, they may run out of suppressants and be temporarily unavailable to assist their peers. Because an agent’s optimal action depends on the actions of others, each agent must not only predict the actions of its peers, but, before that, reason whether they are even present to perform an action. Addressing openness thus requires agents to model each other’s presence, which can be enhanced through agents communicating about …

Revisiting The Complexity Of Racial Understandings And Subjective Experiences Of Race Among Students Of Color In Stem Higher Education: Toward A Racial Reappraisal Framework, Elvira Abrica

Department of Educational Administration: Faculty Publications

Despite significant investment in expanding post-secondary access and success for racially minori­tized populations within science, technology, engineering, and mathematics (STEM) fields, persistent educational disparities remain. While the literature has importantly identified and described the myri­ad ways in which students of color experience exclusion within STEM fields on the basis of race (and, perhaps, other social identity statuses), this area of scholarship is not always theoretically grounded in an understanding of racial hierarchies, processes of racialization, or theories of race and racism. That is, despite the abundant literature on students of color in STEM, there is comparatively limited theo­retical attention to …

Impossible Worlds And The Safety Of Philosophical Beliefs, Zack Garrett, Zachariah Wrublewski

Department of Philosophy: Faculty Publications

Epistemological accounts that make use of a safety condition on knowledge, historically, face serious problems regarding beliefs that are necessarily true. This is because necessary truths are true in all possible worlds, and so such beliefs can be safe even when the bases for the beliefs are epistemically problematic. The existence of such problematically safe beliefs would undermine a major motivation for the condition itself: the ability to evaluate how well a belief tracks the truth. This paper argues that incorporating impossible worlds into the evaluation of beliefs solves this problem, but only if the relevant account of impossible worlds …