Physical Sciences and Mathematics Commons^™

Semiclassical Theory Of Laser-Assisted Dissociative Recombination, Ilya I. Fabrikant, H. B. Ambalampitiya, I. F. Schneider

Department of Physics and Astronomy: Faculty Publications

We study the process of laser-assisted dissociative recombination of an electron with a molecular cation using a semiclassical approach. In the region outside a reaction sphere the electron motion in the combined laser and Coulomb fields is treated classically. Within the sphere the laser-field effects are neglected, and the recombination probability is obtained from quantum-mechanical cross sections calculated for the laser-free process. Specific calculations are performed for dissociative recombination of H₂⁺ in the field of the intensity 2.09 GW/cm² and the wavelength 22.8 μm. In the energy region above 1 meV the cross section is significantly …

Landscape Genetics Of American Beaver In Coastal Oregon, Clinton W. Epps, Vanessa M. Petro, Tyler G. Creech, Rachel S. Crowhurst, Matthew J. Weldy, Jimmy D. Taylor

United States Department of Agriculture Wildlife Services: Staff Publications

American beaver (Castor canadensis) have been translocated for population restoration, reduction of human‐wildlife conflict, and enhancement of ecosystem function. Yet few studies have assessed dispersal of beaver, making it difficult to determine at what scale translocations are appropriate. Genetic studies can provide inferences about gene flow, and thus dispersal. We used a landscape genetic approach to evaluate whether landscape features influenced gene flow among beaver in the Coast Range of western Oregon, USA, using samples collected April–September 2014. We collected genetic samples from live‐captured (n=232), road‐killed (n=2) and trapper‐provided (n=58) tissue samples and genotyped them at 10 microsatellite loci. We …

Magnetism And Topological Hall Effect In Antiferromagnetic Ru2Mnsn-Based Heusler Compounds, Wenyong Zhang, Balamurugan Balasubramanian, Yang Sun, Ahsan Ullah, Ralph Skomski, Rabindra Pahari, Shah R. Valloppilly, Xingzhong Li, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Heusler compounds and alloys based on them are of great recent interest because they exhibit a wide variety of spin structures, magnetic properties, and electron-transport phenomena. Their properties are tunable by alloying and we have investigated L2₁-ordered compound Ru₂MnSn and its alloys by varying the atomic Mn:Sn composition. While antiferromagnetic ordering with a Néel temperature of 361 K was observed in Ru₂MnSn, the Mn-poor Ru₂Mn_0.8Sn_1.2 alloy exhibits properties of a diluted antiferromagnet in which there are localized regions of uncompensated Mn spins. Furthermore, a noncoplanar spin structure, evident from …

Off-Grid Solar Energy Systems Adoption Or Usage - A Bibliometric Study Using The Bibliometrix R Tool, Amartya Ghosh, Dr. V. K. Satya Prasad

Library Philosophy and Practice (e-journal)

Over the years, off-grid solar energy system usage has gained traction around the world - primarily due to the environmental benefits offered, and also facilitating decentralized generation and consumption of electricity in the remote-most pockets. Subsequently, the research on the variety of solar-powered off-grid system applications has attracted much attention and has led to an expansion in the literature. Through a bibliometric analysis, this study aims to identify the most influential research done by academic stakeholders who have contributed in the field of solar off-grid system adoption or usage. To achieve the objectives of the study, peer-reviewed journal articles indexed …

Short Term Safety, Immunogenicity, And Reproductive Effects Of Combined Vaccination With Anti-Gnrh (Gonacon) And Rabies Vaccines In Female Feral Cats, Shiri Novak, Boris Yakobson, Shir Sorek, Liat Morgan, Smadar Tal, Ran Nivy, Roni King, Lauren Jaebker, Douglas C. Eckery, Tal Raz

United States Department of Agriculture Wildlife Services: Staff Publications

Overpopulation of free-roaming cats is a major problem leading to negative impacts on animal health and welfare, public nuisance, transmission of zoonotic diseases, and well-documented harm to wildlife. Surgical sterilization had failed to provide a practical solution to free-roaming cats’ overpopulation under field conditions; therefore, efficient and safe non-surgical immunocontraception methods are aspired. Rabies is a deadly virus that may infect people and animals. However, the safety and efficacy of combined vaccination with anti-GnRH and rabies vaccines in feral cats, which often suffer from disrupted health conditions and experienced high stress level, has never been studied. Therefore, our objective was …

Short Term Safety, Immunogenicity, And Reproductive Effects Of Combined Vaccination With Anti-Gnrh (Gonacon) And Rabies Vaccines In Female Feral Cats, Shiri Novak, Boris Yakobson, Shir Sorek, Liat Morgan, Smadar Tal, Ran Nivy, Roni King, Lauren Jaebker, Douglas C. Eckery, Tal Raz

United States Department of Agriculture Wildlife Services: Staff Publications

Overpopulation of free-roaming cats is a major problem leading to negative impacts on animal health and welfare, public nuisance, transmission of zoonotic diseases, and well-documented harm to wildlife. Surgical sterilization had failed to provide a practical solution to free-roaming cats' overpopulation under field conditions; therefore, efficient and safe non-surgical immunocontraception methods are aspired. Rabies is a deadly virus that may infect people and animals. However, the safety and efficacy of combined vaccination with anti-GnRH and rabies vaccines in feral cats, which often suffer from disrupted health conditions and experienced high stress level, has never been studied. Therefore, our objective was …

Multi-Dimensional Drought Assessment In Abbay/Upper Blue Nile Basin: The Importance Of Shared Management And Regional Coordination Efforts For Mitigation, Yared Bayissa, Semu Moges, Assefa Melesse, Tsegaye Tadesse, Anteneh Z. Abiy, Abeyou Worqlul

Drought Mitigation Center: Faculty Publications

Drought is one of the least understood and complex natural hazards often characterized by a significant decrease in water availability for a prolonged period. It can be manifested in one or more forms as meteorological, agricultural, hydrological, and/or socio-economic drought. The overarching objective of this study is to demonstrate and characterize the different forms of droughts and to assess the multidimensional nature of drought in the Abbay/ Upper Blue Nile River (UBN) basin and its national and regional scale implications. In this study, multiple drought indices derived from in situ and earth observation-based hydro-climatic variables were used. The meteorological drought …

Analysis Of Students’ Multi-Representation Ability In Augmented Reality-Assisted Learning, Sri Jumini, Edy Cahyono, Muhamad Miftakhul Falah

Library Philosophy and Practice (e-journal)

Not all learning sources can directly and cheaply be presented, so augmented reality media is needed to be applied to students with various talents and intelligence. This study aims to analyze students’ multi-representation ability through the use of augmented reality media. The research method was carried out through pre-experiment with one group posttest only design. Test question items were given to see the students’ multi-representation ability. Data analysis was carried out through the percentage of the number of students achieving test scores of more than or equal to 80 on a scale of 100. The results showed that 88% (28 …

Separator Of Diametral Path Graphs, Cuong Than

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Nowadays, graph algorithms have been applied to many practical issues such as networking, very large-scale integration (VLSI), and transport systems, etc. Constructing an algorithm to find a maximum independent set (MIS) is one of the first NP-Hard problems which have been studied for a long time. Most scientists believe that there is no polynomial-time algorithm for this problem in general graphs. However, many efficient algorithms and approximation schemes to resolve the MIS problem are found in some special graph classes. In this thesis, we are going to introduce a separator construction for a diametral path graph. By using a property …

Spirals And Skyrmions In Antiferromagnetic Triangular Lattices, Wuzhang Fang, Aldo Raeliarijaona, Po-Hao Chang, Alexey Kovalev, Kirill Belashchenko

Department of Physics and Astronomy: Faculty Publications

We study realizations of spirals and skyrmions in two-dimensional antiferromagnets with a triangular lattice on an inversion-symmetry-breaking substrate. As a possible material realization, we investigate the adsorption of transition-metal atoms (Cr, Mn, Fe, or Co) on a monolayer of MoS2, WS2, or WSe2 and obtain the exchange, anisotropy, and Dzyaloshinskii-Moriya interaction parameters using first-principles calculations. Using energy minimization and parallel-tempering Monte Carlo simulations, we determine the magnetic phase diagrams for a wide range of interaction parameters. We find that skyrmion lattices can appear even with weak Dzyaloshinskii-Moriya interactions, but their stability is hindered by magnetic anisotropy. However, a weak easy …

Students’ Civic Engagement Self-Efficacy Varies Across Socioscientific Issues Contexts, Jenny Dauer, Amanda E. Sorensen, Jena Wilson

School of Natural Resources: Faculty Publications

In STEM learning focused on science literacy, socioscientific issues instruction is often proposed as a way to bolster students’ civic engagement, however few studies in science education have explicitly examined this connection. We define civic engagement as the work of influencing legitimately public matters using means within the existing political structure. In this work we investigate students’ feelings of self-efficacy for this type of civic engagement in the context of four socioscientific issues (prairie dog conservation, food insecurity, biofuels and water conservation). This study was in the context of a large enrollment introductory science college course, where students used a …

Model Counting Meets F0 Estimation, A. Pavan, N. V. Vinodchandran, Arnab Bhattacharyya, Kuldeep S. Meel

School of Computing: Faculty Publications

Constraint satisfaction problems (CSP’s) and data stream models are two powerful abstractions to capture a wide variety of problems arising in different domains of computer science. Developments in the two communities have mostly occurred independently and with little interaction between them. In this work, we seek to investigate whether bridging the seeming communication gap between the two communities may pave the way to richer fundamental insights. To this end, we focus on two foundational problems: model counting for CSP’s and computation of zeroth frequency moments (F₀) for data streams.

Our investigations lead us to observe striking similarity …

Modernizing Legacy Business Practices And Maintaining Backwards Compatibility When Replacing Legacy Software, Thomas Hillebrandt

Honors Theses

As technology advances and hardware as well as user expectations becomes more advanced, software systems must change alongside or go obsolete. When software is no longer developed, decisions must be made regarding its future. Through various methods, legacy software may continue to see usage far past its obsolescence, however legacy software will sooner or later face replacement by new applications, built for state-of-the-art machines, to comply with modern requirements. When writing new software to replace older programs, the added challenge for developers is to help the client also modernize their workflow. When a program has been in long time use …

Groundwater Education: An Investigation Of Students' Use Of A Groundwater Modeling Tool, Holly White

School of Natural Resources: Dissertations, Theses, and Student Research

Groundwater is a critical resource for life on Earth. However, our groundwater resources are at risk due to human activities, making this a topic of importance within K-12 and undergraduate environmental education. Yet, students hold alternative conceptions and may have limited awareness about groundwater systems. One way to support students’ learning is by incorporating computer-based modeling tools into classrooms. Here, we explore the use a groundwater modeling tool, the Hydrogeology Challenge (HGC), among two age groups of students: seventh grade students and undergraduate students. In the seventh-grade population, we investigated how students relate or map model components to their real-world …

Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko

Kirill Belashchenko Publications

The magnetic anisotropy in MgO-capped MnPt films and its voltage control are studied using first-principles calculations. Sharp variation of the magnetic anisotropy with film thickness, especially in the Pt-terminated film, suggests that it may be widely tuned by adjusting the film thickness. In thick films the linear voltage control coefficient is as large as 1.5 and -0.6 pJ/Vm for Pt-terminated and Mn-terminated interfaces, respectively. The combination of a widely tunable magnetic anisotropy energy and a large voltage-control coefficient suggest that MgO-capped MnPt films can serve as a versatile platform for magnetic memory and antiferromagnonic applications.

Constructing Non-Proxy Small Test Modules For The Complete Intersection Property, Benjamin Briggs, Eloísa Grifo, Josh Pollitz

Department of Mathematics: Faculty Publications

A local ring R is regular if and only if every finitely generated R-module has finite projective dimension. Moreover, the residue field k is a test module: R is regular if and only if k has finite projective dimension. This characterization can be extended to the bounded derived category Df(R), which contains only small objects if and only if R is regular. Recent results of Pollitz, completing work initiated by Dwyer-Greenlees-Iyengar, yield an analogous characterization for complete intersections: R is a complete intersection if and only if every object in Df(R) is proxy small. In this paper, we study a …

Conceptual Framework Linking Resource Size And Recreational Use, Derek Kane

School of Natural Resources: Dissertations, Theses, and Student Research

Participation in recreational activities at natural resource systems is important to many people. However, the use of these resource systems can cause negative social and ecological impacts. To manage the potential negative impacts of resource use, natural resource managers must have the ability to quantify and monitor the amount of use that is occurring. Unfortunately, it is difficult and costly to quantify and monitor resource system use. Natural resource management would benefit from uncovering a simple, easily accessible metric that could predict resource system use. The size of a resource system is related to social and ecological aspects of the …

Museum Exploration Club, Celeste Kenworthy, Aurora Kenworthy

Honors Expanded Learning Clubs

Afterschool club that virtually visits museums in order to help students gain an appreciation for museums and learn about concepts related to art, history, and science.

Population Genomics Of Invasive Rodents On Islands: Genetic Consequences Of Colonization And Prospects For Localized Synthetic Gene Drive, Kevin P. Oh, Aaron B. Shiels, Laura Shiels, Dimitri V. Blondel, Karl J. Campbell, J. Royden Saah, Alun L. Lloyd, Paul Q. Thomas, Fred Gould, Zaid Abdo, John R. Godwin, Antoinette J. Piaggio

United States Department of Agriculture Wildlife Services: Staff Publications

Introduced rodent populations pose significant threats worldwide, with particularly severe impacts on islands. Advancements in genome editing have motivated interest in synthetic gene drives that could potentially provide efficient and localized suppression of invasive rodent populations. Application of such technologies will require rigorous population genomic surveys to evaluate population connectivity, taxonomic identification, and to inform design of gene drive localization mechanisms. One proposed approach leverages the predicted shifts in genetic variation that accompany island colonization, wherein founder effects, genetic drift, and island-specific selection are expected to result in locally fixed alleles (LFA) that are variable in neighboring nontarget populations. Engineering …

“The Revolution Will Not Be Supervised": An Investigation Of The Efficacy And Reasoning Process Of Self-Supervised Representations, Atharva Tendle

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Transfer learning technique enables training Deep Learning (DL) models in a data-efficient way for solving computer vision tasks. It involves pretraining a DL model to learn representations from a large and general-purpose source dataset, then fine-tuning the model using the task-specific target dataset. The dominant supervised learning (SL) approach for pretraining representations suffers from some limitations that include expensive labeling and poor generalizability. Recent advancements in the self-supervised learning (SSL) approach made it possible to learn effective representations from unlabeled data. The performance of the fine-tuned DL models based on pretrained SSL representations is on par with the state-of-the-art pretrained …

Teachability And Interpretability In Reinforcement Learning, Jeevan Rajagopal

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

There have been many recent advancements in the field of reinforcement learning, starting from the Deep Q Network playing various Atari 2600 games all the way to Google Deempind's Alphastar playing competitively in the game StarCraft. However, as the field challenges more complex environments, the current methods of training models and understanding their decision making become less effective. Currently, the problem is partially dealt with by simply adding more resources, but the need for a better solution remains.

This thesis proposes a reinforcement learning framework where a teacher or entity with domain knowledge of the task to complete can assist …

Frobenius And Homological Dimensions Of Complexes, Taran Funk

Department of Mathematics: Dissertations, Theses, and Student Research

Much work has been done showing how one can use a commutative Noetherian local ring R of prime characteristic, viewed as algebra over itself via the Frobenius endomorphism, as a test for flatness or projectivity of a finitely generated module M over R. Work on this dates back to the famous results of Peskine and Szpiro and also that of Kunz. Here I discuss what work has been done to push this theory into modules which are not necessarily finitely generated, and display my work done to weaken the assumptions needed to obtain these results.

Adviser: Tom Marley

Nitrogen Supply And Physical Disturbance Shapes Arctic Stream Nitrogen Uptake Through Effects On Metabolic Activity, Maria Myrstener, Steven A. Thomas, Reiner Giesler, Ryan A. Sponseller

School of Natural Resources: Faculty Publications

1. Climate change in the Arctic is altering the delivery of nutrients from terrestrial to aquatic ecosystems. The impact of these changes on downstream lakes and rivers is influenced by the capacity of small streams to retain such inputs. Given the potential for nutrient limitation in oligotrophic Arctic streams, biotic demand should be high, unless harsh environmental conditions maintain low biomass standing stocks that limit nutrient uptake capacity.

2. We assessed the drivers of nutrient uptake in two contrasting headwater environments in Arctic Sweden: one stream draining upland tundra and the other draining an alluvial valley with birch forest. At …

Polarimetric Radar Characteristics Of Tornadogenesis Failure In Supercell Thunderstorms, Matthew S. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Many nontornadic supercell storms have times when they appear to be moving toward tornadogenesis, including the development of a strong low-level vortex, but never end up producing a tornado. These tornadogenesis failure (TGF) episodes can be a substantial challenge to operational meteorologists. In this study, a sample of 32 pre-tornadic and 36 pre-TGF supercells is examined in the 30 min pre-tornadogenesis or pre-TGF period to explore the feasibility of using polarimetric radar metrics to highlight storms with larger tornadogenesis potential in the near-term. Overall the results indicate few strong distinguishers of pre-tornadic storms. Differential reflectivity (Z_DR) arc size …

Challenges And Opportunities In Precision Irrigation Decision-Support Systems For Center Pivots, Jingwen Zhang, Kaiyu Guan, Bin Peng, Chongya Jiang, Wang Zhou, Yi Yang, Ming Pan, Trenton Franz, Derek M. Heeren, Daran R. Rudnick, Olufemi P. Abimbola, Hyungsuk Kimm, Kelly Caylor, Stephen Good, Madhu Khanna, John Gates, Yaping Cai

Department of Biological Systems Engineering: Papers and Publications

Irrigation is critical to sustain agricultural productivity in dry or semi-dry environments, and center pivots, due to their versatility and ruggedness, are the most widely used irrigation systems. To effectively use center pivot irrigation systems, producers require tools to support their decision-making on when and how much water to irrigate. However, currently producers make these decisions primarily based on experience and/or limited information of weather. Ineffective use of irrigation systems can lead to overuse of water resources, compromise crop productivity, and directly reduce producers’ economic return as well as bring negative impacts on environmental sustainability. In this paper, we surveyed …

Bioaccumulation And Partitioning Of Heavy Metals In Cicindelidia Haemorrhagica In Yellowstone National Park, Monica Gotschall

School of Natural Resources: Dissertations, Theses, and Student Research

The tiger beetle Cicindelidia haemorrhagica (Coleoptera: Cicindelidae) are widely distributed in Yellowstone National Park (YNP) and exclusively living on thermal areas. Heavy metals including arsenic, copper, lead, and selenium are present in these thermal springs, presenting an unique environment for C. haemorrhagica. Therefore, from 2018 – 2020 I sampled adult C. haemorrhagica from YNP and adult C. haemorrhagica from a known population in a salt flat in Idaho not associated with a hot spring and measured heavy metal concentrations. All populations of C. haemorrhagica bioaccumulated heavy metals. Cuticular waxes showed small concentrations of metals indicating that those metals are …

Structure Formation And Coupling Reactions Of Hexaphenylbenzene And Its Brominated Analog, Jacob D. Teeter, Paulo S. Costa, Christoph Dobner, Mamun Sarker, Alexander Sinitskii, A Enders

Chemistry Department: Faculty Publications

The on-surface coupling of the prototypical precursor molecule for graphene nanoribbon synthesis, 6,11-dibromo-1,2,3,4-tetraphenyltriphenylene (C₄₂Br₂H₂₆, TPTP), and its non-brominated analog hexaphenylbenzene (C₄₂H₃₀, HPB), was investigated on coinage metal substrates as a function of thermal treatment. For HPB, which forms non-covalent 2D monolayers at room temperature, a thermally induced transition of the monolayer’s structure could be achieved by moderate annealing, which is likely driven by π-bond formation. It is found that the dibrominated carbon positions of TPTP do not guide the coupling if the growth occurs on a substrate at temperatures that …

The Analysis Of Groundwater Recharge In Mongolia Using Vadose Zone Modeling, Khulan Batsukh

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Knowledge of groundwater recharge (GR) is vital for optimal water resources management under an arid continental climate. However, in vast territories such as Mongolia, direct measurements of GR are unfeasible because they mandate excessive costs, stemming from time-consuming and labor-demanding efforts. A valid alternative to direct measurements is numerical models based on the monitoring of precipitation (P) and evapotranspiration (ET) for simulating GR. While direct measurements of ET are logistically problematic and unpractical for large-scale applications, a reliable prediction may be derived from crop reference evapotranspiration (ET₀) which is calculable …

Surface Functionalization Of Elastomers For Tunable Crystal Growth And Smart Adhesives, John Kapitan

Department of Chemistry: Dissertations, Theses, and Student Research

Silicone rubbers have seen extensive work on modulation of their surface environments for use in microfluidics, cell adhesion, and sensing. Most surface procedures utilize a common initial step of oxidation of the surface to increase the number of active surface functional groups. Following oxidation more permanent functionalities can be imparted on the surface using silanization, grafting polymer brushes, or creating ionic bonds to the surface. Of these three, silanization proves to be the most pervasive due to the range of procedures available and how easy the procedures prove to be. However, the mechanism by which silanization is performed heavily involves …

Informing Drought Mitigation Policy By Estimating The Value Of Water For Crop Production, Renata Rimsaite, Justin Gibson, Nicholas Brozovic

School of Natural Resources: Faculty Publications

Farmers use irrigation to mitigate drought risk and reduce yield uncertainty. A clear understanding of the monetary value of irrigation water and how it varies across time and space can help to inform farmers and policymakers about the potential impacts of water shortages and reduce uncertainty in decision making. Here, we introduce a framework for understanding the economic value of water used to produce corn in the central High Plains region during the period 2010–2017. Our analysis uses publicly available data for corn price and for irrigated and non-irrigated yields and incorporates irrigation requirement adjustments to account for the hydrologic …