Physical Sciences and Mathematics Commons^™

Efficient Perpendicular Magnetization Switching By A Magnetic Spin Hall Effect In A Noncollinear Antiferromagnet, Shuai Hu, Ding-Fu Shao, Huanglin Yang, Chang Pan, Zhenxiao Fu, Meng Tang, Yumeng Yang, Weijia Fan, Shiming Zhou, Evgeny Y. Tsymbal, Xuepeng Qiu

Department of Physics and Astronomy: Faculty Publications

Current induced spin-orbit torques driven by the conventional spin Hall effect are widely used to manipulate the magnetization. This approach, however, is nondeterministic and inefficient for the switching of magnets with perpendicular magnetic anisotropy that are demanded by the high-density magnetic storage and memory devices. Here, we demonstrate that this limitation can be overcome by exploiting a magnetic spin Hall effect in noncollinear antiferromagnets, such as Mn3Sn. The magnetic group symmetry of Mn₃Sn allows generation of the out-of-plane spin current carrying spin polarization collinear to its direction induced by an in-plane charge current. This spin current drives an …

Nonbreeding Season Survival And Habitat Selection Of Northern Bobwhite In Northeastern Colorado, Joseph M. Wolske

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

Northern bobwhites (Colinus virginianus) have experienced range-wide population declines. Recent harvest data from northeastern Colorado suggests bobwhite populations have declined and populations can be sensitive to adult nonbreeding season survival. We monitored 157 bobwhites in northeastern Colorado, on the northern periphery of the species’ range, for the 2019-2020 and 2020-2021 nonbreeding seasons to estimate nonbreeding season survival and habitat selection. We used known-fate survival models to assess any variation in survival between the winter stages of early-winter, mid-winter, and late-winter, as well as sex, age class, and mass at the time of capture. Survival varied among winter stages, …

Towards Usable Environmental Information: A Case Study With The Santee Sioux Nation, Alexis Chavez

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

Across the United States (U.S.), Indigenous peoples have developed and implemented adaptation plans to improve their resilience to climate and weather disturbances. An essential component of these plans is to use environmental information effectively. Institutions like universities and government agencies usually provide this information, and its usability depends on the information’s quality and the relationships that establish its accessibility and validity. However, many studies have shown that much of this information is not usable for its intended users. Additionally, there has been little research into the issues that can affect Indigenous peoples’ usage of environmental information in the U.S. Therefore, …

Evidence For An Early Saginaw Lobe Ice Retreat And Drainage Adjustments Across Southern Michigan, Usa, Nathan Erber

Dissertations

The Saginaw lobe of the Laurentide Ice Sheet (LIS), flowed out of Saginaw Bay, across Lower Michigan and into northern Indiana. As it retreated, the Saginaw lobe deposited the Sturgis moraine, a recessional moraine of the lobe in southern Michigan. Positioned to the west and east of the Saginaw lobe were the Lake Michigan and Huron-Erie lobes, respectively. These lobes retreated across the region asynchronously, with the Saginaw lobe retreating first. The asynchronous behavior of the lobes allowed for the Lake Michigan and Huron-Erie lobes to overprint and alter landscapes once occupied by the Saginaw lobe ice.

The Kalamazoo moraine, …

Understanding Learners' Motivation Through Machine Learning Analysis On Reflection Writing, Elizabeth Pluskwik, Yuezhou Wang, Lauren Singelmann

Integrated Engineering Department Publications

Educational data mining (EDM) is an emerging interdisciplinary field that utilizes a machine learning (ML) algorithm to collect and analyze educational data, aiming to better predict students' performance and retention. In this WIP paper, we report our methodology and preliminary results from utilizing a ML program to assess students’ motivation through their upper-division years in the XYZ project-based learning (PBL) program. ML, or more specifically, the clustering algorithm, opens the door to processing large amounts of student-written artifacts, such as reflection journals, project reports, and written assignments, and then identifies keywords that signal their levels of motivation (i.e., extrinsic vs. …

Data Augmentation Strategies For Eeg-Based Motor Imagery Decoding, Olawunmi George, Roger Smith, Praveen Madiraju, Nasim Yahyasoltani, Sheikh Iqbal Ahamed

Computer Science Faculty Research and Publications

The wide use of motor imagery as a paradigm for brain-computer interfacing (BCI) points to its characteristic ability to generate discriminatory signals for communication and control. In recent times, deep learning techniques have increasingly been explored, in motor imagery decoding. While deep learning techniques are promising, a major challenge limiting their wide adoption is the amount of data available for decoding. To combat this challenge, data augmentation can be performed, to enhance decoding performance. In this study, we performed data augmentation by synthesizing motor imagery (MI) electroencephalography (EEG) trials, following six approaches. Data generated using these methods were evaluated based …

Variational And Covariational Reasoning Of Students With Disabilities, Lauren Rigby

Theses and Dissertations

Mathematics education reform has led to more conceptually focused instruction in the classroom. Yet, students with disabilities are receiving fewer chances than other students to engage in meaningful mathematics. Furthermore, a research divide between mathematics education and special education in mathematics has led to significant gaps in research on the individual and conceptual understanding of students with disabilities. Through task-based interviews and classroom observations, this study begins the process of closing this research gap through an examination of students' understanding of variational and covariational reasoning. Data suggest that the participants, two students with disabilities, increased their conceptual understanding in a …

Using Machine Learning To Classify Volleyball Jumps, Miki Jauhiainen

Theses and Dissertations

In this study, inertial measurement units (IMUs) were used to train a random forest classifier to correctly classify different jump types in volleyball. Athlete motion data were collected in a controlled setting using three IMUs, one on the waist and one on each ankle. There were 11 participants who at the time played volleyball at the collegiate level in the United States, seven male and four female. Each performed the same number of jumps across the eight jump types--five BASIC jumps and three each of the other seven--resulting in 26 jumps per subject for a total of 286. The data …

Fabrication And Characterization Of Dna Templated Electronic Nanomaterials And Their Directed Placement By Self-Assembly Of Block Copolymers, Dulashani Ruwanthika Ranasinghe Weerakkodige

Theses and Dissertations

Bottom-up self-assembly has the potential to fabricate nanostructures with advanced electrical features. DNA templates have been used to enable such self-assembling methods due to their versatility and compatibility with various nanomaterials. This dissertation describes research to advance several different steps of biotemplated nanofabrication, from DNA assembly to characterization. I assembled different nanomaterials including surfactant-coated Au nanorods, DNA-linked Au nanorods and Pd nanoparticles on DNA nanotubes ~10 micrometer long, and on ~400 nm long bar-shaped DNA origami templates. I optimized seeding by changing the surfactant and magnesium ion concentrations in the seeding solution. After successful seeding, I performed electroless plating on …

Deep Active Genetic Learning With Evidential Uncertainty For Agriculture Crops And Lake Water Quality Assessment, Oguz M. Aranay

Legacy Theses & Dissertations (2009 - 2024)

Despite significant advancements in the field of machine learning, there are two issues that still require further exploration. First, how to learn from a small dataset; and second, how to select appropriate features from the data. Although there exist many techniques to address these issues, choosing a combination of the techniques from these two groups is challenging, and worth investigating. To address these concerns, this thesis presents a learning framework that is based on a deep learning model utilizing active learning (with evidential uncertainty as a basis for acquisition function) for the first issue and a genetic algorithm for the …

Deep Learning For Protein Property And Structure Prediction, Yuzhi Guo

Computer Science and Engineering Dissertations

I present my work towards solving the fundamental, challenging, and valuable problem for protein property and structure prediction. Specifically, I focus on solving the problem from three critical aspects: (1) designing powerful deep learning networks for specific protein structure property prediction tasks; (2) proposing general methods that enhancing the protein sequence homologous feature, which is an important input feature of relevant tasks; (3) developing a self-supervised pre-training model for learning structure embeddings from protein tertiary structures. To evaluate the effectiveness of the developed methods, I apply several protein downstream tasks including protein secondary structure, solvent accessibility, backbone dihedral angles, protein …

Semi Automatic Hand Pose Annotation Using A Single Depth Camera, Marnim Galib

Computer Science and Engineering Dissertations

This thesis investigates the problem of 3D hand pose annotation using a single depth camera. While hand pose annotations are critically important for training deep neural networks, creating such reliable training data is challenging and manual labor intensive. Current datasets that rely on manual annotation on real images are limited in size due to the difficulty of annotating them. Although, large datasets have been generated using tracking based methods followed by manual refinement, these methods are prone to annotation errors due to tracking failure. Synthetic images have also been used to create large datasets but synthetic frames does not capture …

Glaciochemical Investigations In Three Southern Hemisphere Mountain Sites, Mariusz Potocki

Electronic Theses and Dissertations

The research presented in this dissertation focuses on glaciochemical records of trace elements, major ions, and stable water isotopes from three mountain regions: the Antarctic Peninsula, the Central Chilean Andes, and South Georgia Island.

The first section reports a significant increase in U concentration over 27 years on Detroit Plateau, Antarctic Peninsula. U concentrations in the ice core increase by as much as 102 between the 1980s and 2000s, accompanied by increased variability in recent years. The U concentration increase coincides with expanded open pit mining in the Southern Hemisphere, most notably Australia. Since other land-source dust elements do not …

El Niño And The Human-Environment Nexus: Drought And Vulnerability In Singapore 1877-1911, Fiona Williamson

Research Collection College of Integrative Studies

This chapter brings a climatic perspective to the study of Singaporean history by exploring the impacts of the strong El Niño inspired droughts of 1877, 1902 and 1911. The narrative focuses on unpacking the nexus of nature-inspired versus human-induced vulnerability to drought within the contexts of colonial urbanisation and looks at the short-to medium-term impacts of the events on society. It also explores how such events inspired new questions about the climate and regional teleconnections, as a wealth of evidence became available due to the increasingly connected nature of scientific institutions, scientific literature, and communications systems across the Indian Ocean …

An Integral Transform For Quantum Amplitudes, Jack C. Straton

Physics Faculty Publications and Presentations

The central impediment to reducing multidimensional integrals of transition amplitudes to analytic form, or at least to a fewer number of integral dimensions, is the presence of magnitudes of coordinate vector differences (square roots of polynomials) |x1−x2|2=x21−2x1x2cosθ+x2 √ in disjoint products of functions. Fourier transforms circumvent this by introducing a three-dimensional momentum integral for each of those products, followed in many cases by another set of integral transforms to move all of the resulting denominators into a single quadratic form in one denominator whose square my be completed. Gaussian transforms introduce a one-dimensional integral for each such product while squaring …

Evaluating Spatial-Temporal Patterns In Us Tornado Occurrence With Space Time Cube Analysis And Linear Kernel Density Estimation: 1950-2019, Darrell L. Wiser

Electronic Theses and Dissertations

This research estimated the spatial-temporal patterns of tornadoes in the continental United States from 1950-2019 using the National Weather Service Storm Prediction Center’s Severe Weather GIS (SVRGIS) database. This study employed Space-Time Cube Analysis and Linear Kernel Density (Kernel Density Linear Process, (KDLP)) rather than the standard Kernel Density Estimation (KDE) approach; to evaluate whether tornado hotspot locations and intensities shift over time.

The first phase of the study utilized KDLP to map changes in tornado hotspots and qualitatively assess decadal shifts in hotspot locations and intensities by occurrence and magnitude between decades using ArcGIS Pro and CrimeStat. Next an …

An Evaluation Of Castor Californicus And Implications For The Evolution And Distribution Of The Genus Castor (Rodentia: Castoridae) In North America, Kelly Lubbers

Electronic Theses and Dissertations

The genus Castor is represented in Eurasia by Castor fiber, North America by C. canadensis, and has been in North America since the late Miocene. This study aims to assess whether morphology of Miocene-Pliocene C. californicus and extant C. canadensis are distinctly different. Specimens of Castor were compared using geometric morphometrics on cranial material and linear measurements of postcranial material. Species occurrence data were compared with past and future climate data to assess Castor distribution in North America through time. Results show that C. canadensis is highly variable in both cranial and postcranial morphology and C. californicus falls …

Arrayed Waveguide Lens For Beam Steering, Mostafa Honari-Latifpour, Ali Binaie, Mohammad Amin Eftekhar, Nicholas Madamopoulos, Mohammad-Ali Miri

Publications and Research

Integrated planar lenses are critical components for analog optical information processing that enable a wide range of applications including beam steering. Conventional planar lenses require gradient index control which makes their on-chip realization challenging. Here, we introduce a new approach for beam steering by designing an array of coupled waveguides with segmented tails that allow for simultaneously achieving planar lensing and off-chip radiation. The proposed arrayed waveguide lens is built on engineering the evanescent coupling between adjacent channels to realize a photonic lattice with an equi-distant ladder of propagation constants that emulates the continuous parabolic index profile. Through coupled-mode analysis …

Data-Driven Population Inference From Gravitational-Wave Sources And Electromagnetic Counterparts, Siddharth Mohite

Theses and Dissertations

Gravitational-wave (GW) astronomy has presented an unprecedented way to view the universe and study populations of astrophysical objects such as merging compact binaries containing black holes (BHs) and neutron stars (NSs). With the latest catalog of observations detected by the Advanced LIGO-Virgo detector network, recent analyses are placing interesting constraints on the population of BHs and NSs in these binaries. In particular, we are learning a great deal about how these binaries are distributed as a function of their masses. Another aspect of GW astronomy that has the potential to provide insights into fundamental physics is the multi-messenger follow up …

Absolute Quantification Of Tc-99m Activity Distributions Using A Planar Molecular Breast Imaging Commercial System, Benjamin P. Lopez

Dissertations & Theses (Open Access)

Molecular breast imaging (MBI) uses two dedicated-breast semiconductor detectors to visualize the preferential uptake of technetium-99m-sestamibi (^99mTc-sestamibi) by breast cancer cells relative to surrounding benign breast tissues. Clinically, MBI is used primarily as a supplementary tool to standard-of-care mammography because of its improved detection of breast cancers, especially in women with mammographically-dense breasts. Because of a lack of image corrections, MBI applications are currently limited to qualitative evaluations of relative pixel intensities between image regions with suspected lesions and normal tissue.

The objective of this dissertation was to use Monte Carlo simulations to better characterize the MBI imaging …

Dvr-Matroids Of Algebraic Extensions, Anna L. Lawson

Doctoral Dissertations

A matroid is a finite set E along with a collection of subsets of E, called independent sets, that satisfy certain conditions. The most well-known matroids are linear matroids, which come from a finite subset of a vector space over a field K. In this case the independent sets are the subsets that are linearly independent over K. Algebraic matroids come from a finite set of elements in an extension of a field K. The independent sets are the subsets that are algebraically independent over K. Any linear matroid has a representation as an algebraic matroid, but the converse is …

The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier

Electronic Theses and Dissertations

The national mammal of the United States, the American Bison (Bison bison) was once nearly extinct. Populations have recovered to the degree that thousands roam the Great Plains today. Due to their large numbers and body size, this species has an oversized impact on the ecological communities where it lives and is considered a keystone herbivore in modern North American grasslands. This study explores the detailed, seasonally resolved, paleoecology of seven bison from the Greater Yellowstone Ecosystem during the Late Holocene through stable isotope analyses and species niche modeling. Isotopic analyses of δ¹³C, δ¹⁵N, …

Mercury Methylation Potentials In Sediments Of An Ancient Cypress Wetland Using Species-Specific Isotope Dilution Gc-Icp-Ms, Derek D. Bussan, Chris Douvris, James V. Cizdziel

Faculty and Student Publications

Wetlands are of a considerable environmental value as they provide food and habitat for plants and animals. Several important chemical transformations take place in wetland media, including the conversion of inorganic mercury (Hg) to monomethylmercury (MeHg), a toxic compound with a strong tendency for bioconcentration. Considering the fact that wetlands are hotspots for Hg methylation, we investigated, for the first time, Hg methylation and demethylation rates in an old growth cypress wetland at Sky Lake in the Mississippi Delta. The Sky Lake ecosystem undergoes large-scale water level fluctuations causing alternating periods of oxic and anoxic conditions in the sediment. These …

Identification And Quantitation Of Unspecified Impurities Discovered In Novel Oral Irinotecan By Lc-Ms/Ms And Uhplc, Laura B. Miller

Forensic Science Master's Projects

Irinotecan is a cancer medication approved for medical use in the United States in 1996. It is currently administered via intravenous injection. However, intravenous dosing has disadvantages such as requirement of administration by a trained professional in a medical facility, possible severe adverse effects, pain at the injection site, and possible hemolysis if injected too rapidly. Previously oral administration was not feasible because the p-glycoprotein (p-GP) on the cell membrane of stomach cells acts as a defense mechanism against harmful substances by pumping the irinotecan back into the intestinal lumen for excretion. With the discovery of the p-GP inhibitor encequidar …

Frameworks For Secure Collaborative And Concurrent Editing, Shashank Arora

Legacy Theses & Dissertations (2009 - 2024)

Cloud-based online document editing services, such as Google Docs and Office 365, provide an inexpensive and efficient means of managing documents. However, storing data on the cloud also raises certain security and privacy concerns, especially when the data is of confidential and sensitive nature. Storing data on third-party servers can potentially be compromising as it gives an opportunity to the third-party cloud service providers to turn semi-honest and become curious about user data. User data stored on third-party servers is also prone to attacks like virtual machine-based side-channel along with natural language processing and machine learning-based content search and retrieval …

An Ims-Ms/Md Workflow For Determining Higher Order Structure And Dynamics Of Nucleic Acids, Rebecca D'Esposito

Legacy Theses & Dissertations (2009 - 2024)

Ion mobility spectrometry - mass spectrometry (IMS-MS) has potential for the investigation of structure and dynamics in large biopolymers, which will come to full fruition only with a firmer understanding of how to interpret the experimental data. Numerous studies have employed elements of nucleic acid (NA) secondary structure, such as duplexes and hairpins, to explore the relationships between structure, experimental conditions, and actual observations. When combined with molecular dynamics simulations (MDS), IMS-MS can be effectively employed to perform structural elucidation of biomolecules that are not readily amenable to established techniques employed for structural analysis.

Human-Wildlife Coexistence With Coyotes In Los Angeles County, Ca And Cook County, Il, Alan Eapen

Legacy Theses & Dissertations (2009 - 2024)

The expansion of coyotes (Canis latrans) into urban and suburban areas where human concentration is high has led to human-coyote conflicts often leading to increased management actions against coyotes. Recently in Los Angeles and Cook Counties, municipalities have developed coyote management plans to foster human-wildlife coexistence in an effort to reduce conflict, an emerging concept that promotes the cohabitation of humans and animals in shared landscapes. The thesis investigates coyote management plans and policies concerning human-coyote interactions in Los Angeles and Cook Counties to address human-wildlife. Using a case study analysis of Los Angeles and Cook Counties, this study analyzed …

Examining The Impact Of Stratospheric Vortex Variability On Us Surface Temperature, Elena M. Fernandez

Legacy Theses & Dissertations (2009 - 2024)

Variability in high-latitude stratospheric flow, including major sudden stratospheric warming (SSW) or strong polar vortex events, can modulate tropospheric circulation and have meteorological implications on surface temperature and weather. The largest tropospheric impacts from Northern Hemisphere stratospheric variability – and the regions of focus in the literature – are observed in the North Atlantic, Europe and Asia. Impacts on North America occur but have received less research attention. The goal of this thesis research is to identify and quantify the relationship between high-latitude stratospheric variability and North American wintertime temperature.Using the ERA-Interim and ERA-5 reanalysis for the period of 1999/2000–2018/19, …

A Comparative Analysis Of The Impact Of Low-Level Jets And Atmospheric Rivers In The Central U.S, Nabindra Gyawali

Legacy Theses & Dissertations (2009 - 2024)

Atmospheric Rivers (AR) are the primary source of poleward moisture transport globally. In theUnited States, much recent attention has been placed on Pacific Coast ARs which occur between December and March. However, the central US is also substantially impacted by warm-season AR. An open question is whether these warm-season ARs are synonymous with Great Plains low-level jets (LLJs) that have long served as a focal point of mesoscale atmospheric research. In this study, we perform a comparative analysis of ARs and LLJs in the central U.S using ECMWF’s climate-quality reanalysis of the 20th century, CERA-20C. The aim is to identify …

Changes In Large-Scale Extreme Precipitation In Over Taiwan And The Northeast United States : Past And Future, Lexi Henny

Legacy Theses & Dissertations (2009 - 2024)

Large-scale extreme precipitation over (1) the mid-Atlantic and Northeast United States and (2) Taiwan is attributed to weather types such as atmospheric river (AR), TC, and extreme integrated vapor transport (IVT). Statistically significant increases in season-total EP day precipitation are seen at many GHCN stations in winter, summer, and fall in the mid-Atlantic and Northeast region, and at certain high-elevation grid points in Taiwan Mei-yu season. During the cold season of winter and spring, the U.S.-based changes come from AR-associated EP days and are associated with strengthened southwesterly winds and IVT either within EP days, in the season mean, or …