Physical Sciences and Mathematics Commons^™

Capacity-Weighted Figures-Of-Merit For Battery Transport Metrics, Cj Sturgill, Christopher Sutton, Julian Schwenzel, Morgan Stefik

Faculty Publications

New battery materials with improved transport are needed. Typical measurements yield widely varying voltage-dependent diffusivities and reporting practices are diverse. Some materials (e.g. first-order phase change) have most redox occur at a specific voltage and may be sufficiently represented by singular transport metrics. Many rapid intercalation materials, however, exhibit second-order phase transitions with redox over a broad voltage range. How should such cases be compared? The use of capacity-weighted average values is suggested where voltage-dependent metrics are consolidated into representative descriptors as figures-of-merit. Examples are elaborated where differential capacity (dQ/dV) is used to derive a …

Mental Health Care Disparities Among Us Pregnant Individuals In 2020–2021: A Cross-Sectional Study, Julisa Tindall, Monique J. Brown Ph.D., Mph, Peiyin Hung

Faculty Publications

Purpose

To examine maternal characteristics associated with perceived unmet mental health needs and mental health care settings, focusing on residential rurality and race/ethnicity.

Methods

This cross-sectional study analyzed self-reported unmet mental health needs and mental health care settings among 1097 pregnant respondents in the 2020–2021 National Survey on Drug Use and Health, incorporating the complex sampling weights for national representativeness.

Findings

Non-Hispanic Black pregnant individuals and those living in nonmetro rural areas reported lower odds of unmet mental health needs compared to those in large metro areas and non-Hispanic White individuals. Pregnant individuals in nonmetro rural areas and non-Hispanic other …

Organic Alkalinity Distributions, Characteristics, And Application To Carbonate System Calculations In Estuarine And Coastal Systems, Christopher W. Hunt, Joseph Salisbury, Xuewu Liu, Robert H. Byrne

Faculty Publications

The capacity of aquatic systems to buffer acidification depends on the sum contributions of various chemical species to total alkalinity (TA). Major TA contributors are inorganic, with carbonate and bicarbonate considered the most important. However, growing evidence shows that many rivers, estuaries, and coastal waters contain dissolved organic molecules with charge sites that create organic alkalinity (OrgAlk). This study describes the first comparison of (1) OrgAlk distributions and (2) acid–base properties in contrasting estuary-plume systems: the Pleasant (Maine, USA) and the St. John (New Brunswick, CA). The substantial concentrations of OrgAlk in each estuary were sometimes not conservative with salinity …

New Insights Into Supradense Matter From Dissecting Scaled Stellar Structure Equations, Bao-Jun Cai, Bao-An Li

Faculty Publications

The strong-field gravity in general relativity (GR) realized in neutron stars (NSs) renders the equation of state (EOS) P(ε) of supradense neutron star matter to be essentially nonlinear and refines the upper bound for ϕ≡P/ε to be much smaller than the special relativity (SR) requirement with linear EOSs, where P andεare respectively the pressure and energy density of the system considered. Specifically, a tight bound ϕ ≲ 0.374 is obtained by perturbatively anatomizing the intrinsic structures of the scaled Tolman–Oppenheimer–Volkoff (TOV) equations without using any input nuclear EOS. New insights gained from this novel analysis provide EOS-model-independent constraints on the …

Ultraviolet And Blue Stimulated Emission From Cs Alkali Vapor Pumped Using Two-Photon Absorption And Four-Wave Mixing, Ricardo C. Davila, Christopher A. Rice, Nathan B. Terry, Glen P. Perram

Faculty Publications

Stimulated emission on the ultraviolet and blue transitions in Cs has been achieved by pumping via two-photon absorption and four-wave mixing for the pump transition 6²S½ → 8²D_3/2,5/2. The emission performance of the optically pumped cesium vapor laser operating in ultraviolet and blue has been extended to 650 nJ/pulse for 387 nm, 1 to 3 μ J / pulse for 388 nm, 200 nJ/pulse for 455 nm, and 500 nJ/pulse for 459 nm. Emission performance improves dramatically as the cesium vapor density is increased, and no scaling limitations associated with energy pooling or …

Na2B12Si6Se18: A Novel B12-Cluster-Containing Quaternary Selenoborate Framework Material, Gopabandhu Panigrahi, Hunter B. Tisdale, Gregory Morrison, Hans Conrad Zur Loye

Faculty Publications

We report the successful synthesis of the new quaternary, three-dimensional Na₂B₁₂Si₆Se₁₈ material using a solid-state synthesis route. This compound is characterized by a unique framework structure that features the rare icosahedral [B₁₂]¹⁰⁺ cation which is connected via Si2Se6 polyhedral units into a 3D framework structure with Na+ ions located inside the channels. The Na₂B₁₂Si₆Se₁₈ compound crystallizes in the cubic crystal system in the space group Im, with lattice parameter a = 11.91110(10) Å and unit cell volume of 1689.88(4) ų. …

Machine Visual Perception From Sim-To-Real Transfer Learning For Autonomous Docking Maneuvers, Derek Worth, Jeffrey Choate, Ryan M. Raettig, Scott L. Nykl, Clark N. Taylor

Faculty Publications

This paper presents a comprehensive approach to enhancing autonomous docking maneuvers through machine visual perception and sim-to-real transfer learning. By leveraging relative vectoring techniques, we aim to replicate the human ability to execute precise docking operations. Our study focuses on autonomous aerial refueling as a use case, demonstrating significant advancements in relative navigation and object detection. We introduce a novel method for aligning digital twins using fiducial targets and motion capture data, which facilitates accurate pose estimation from real-world imagery. Additionally, we develop cost-efficient annotation automation techniques for generating high-quality You Only Look Once training data. Experimental results indicate that …

Everyone Brings Something To The Table: A Culturally Sustaining Analysis Of Teacher Candidates’ Mixed Reality Teaching Simulations, Erin Scott

Faculty Publications

Discussions of HBCU students’ content knowledge have centered around developing high impact, asset-based approaches to learning (Williams et al, 2022). So, HBCU teacher preparation providers (TPPs) can also focus efforts on culturally sustaining approaches to developing candidates’ content knowledge and researching how high impact practices, like teaching simulations, can help prepare candidates for classrooms. This exploratory case study uses critical cases (n=2); findings suggest candidates have a developing understanding of content, which forms a solid basis for increasing their knowledge. MRTSs are addressed as a potential high impact, culturally sustaining practice for building candidates’ content knowledge. Further, HBCU TPPs can …

Investigation Of Magnesium-Potassium Phosphates As Potential Nuclear Waste Form For The Immobilization Of Minor Actinides, Hans Conrad Zur Loye, Petr Vecernik, Monika Kiselova, Vlastislav Kašpar, Hana Korenkova, Vlastimil Miller, Petr Bezdicka, Jan Šubrt, Natalija Murafa, Volodymyr Shkuropatenko, Sergey Sayenko

Faculty Publications

Several recent studies have evaluated technologies of spent nuclear fuel processing specifically for solidifying transuranic (TRU) waste as a by-product of fission. Of the TRU group, plutonium and the minor actinides will be responsible for the bulk of the radiotoxicity and heat generation of spent nuclear fuel in the long term (300 to 20,000 years). In this study, we investigated magnesium potassium phosphate (MKP)-based compounds as host waste forms for the encapsulation of inactive trivalent Nd and Sm as analogues of the minor trivalent actinides, Am and Cm. Waste forms were fabricated under ambient atmospheric conditions by adding 5 wt.% …

Temporal Metadata Analysis: A Learning Classifier System Approach, Michael C. Todd, Gilbert L. Peterson

Faculty Publications

Digital forensics is a complex field that requires expert knowledge (EK) and specialized tools to collect, analyze, and report on digital evidence. Temporal metadata analysis is particularly challenging, requiring expert knowledge to understand and interpret underlying traces and associate them with their source. This paper introduces Digital Trace Inspector (DTI), a Learning Classifier System (LCS)-based decision support tool for temporal metadata analysis. DTI leverages a binary Michigan-style LCS to locate and group corroborating temporal digital traces of targeted user activity. Rules are built from expert-created atomics encoded as feature vectors using patterns defined in a structured EK rule framework. The …

Spatial Pattern And Differential Expression Analysis With Spatial Transcriptomic Data, Fei Qin, Xizhi Luo, Bo Cai Ph.D., Feifei Xiao, Guoshuai Cai

Faculty Publications

The emergence of spatial transcriptomic technologies has opened new avenues for investigating gene activities while preserving the spatial context of tissues. Utilizing data generated by such technologies, the identification of spatially variable (SV) genes is an essential step in exploring tissue landscapes and biological processes. Particularly in typical experimental designs, such as case-control or longitudinal studies, identifying SV genes between groups is crucial for discovering significant biomarkers or developing targeted therapies for diseases. However, current methods available for analyzing spatial transcriptomic data are still in their infancy, and none of the existing methods are capable of identifying SV genes between …

Bound States And Particle Production By Breather-Type Background Field Configurations, Abhishek Rout, Brett Altschul

Faculty Publications

We investigate the interaction of fermion fields with oscillating domain walls, inspired by breather-type solutions of the sine-Gordon equation, a nonlinear system of fundamental importance. Our study focuses on the fermionic bound states and particle production induced by a time-dependent scalar background field. The fermions couple to two domain walls undergoing harmonic motion, and we explore the resulting dynamics of the fermionic wave functions. We demonstrate that while fermions initially form bound states around the domain walls, the energy provided by the oscillatory motion of the scalar field induces an outward flux of fermions and antifermions, leading to particle production …

Applying Machine‐Learning Methods To Laser Acceleration Of Protons: Lessons Learned From Synthetic Data, Ronak Desai, Thomas Zhang, J. J. Felice, Ricky Oropeza, Joseph R. Smith, Alona Kryshchenko, Chris Orban, Michael L. Dexter, Anil K. Patnaik

Faculty Publications

In this study, we consider three different machine-learning methods—a three-hidden-layer neural network, support vector regression, and Gaussian process regression—and compare how well they can learn from a synthetic data set for proton acceleration in the Target Normal Sheath Acceleration regime. The synthetic data set was generated from a previously published theoretical model by Fuchs et al. 2005 that we modified. Once trained, these machine-learning methods can assist with efforts to maximize the peak proton energy, or with the more general problem of configuring the laser system to produce a proton energy spectrum with desired characteristics. In our study, we focus …

Strategies To Alleviate Flickering: Bayesian And Smoothing Methods For Deep Learning Classification In Video, Noah Miller, Glen Ryan Drumm, Lance Champagne, Bruce A. Cox, Trevor Bihl

Faculty Publications

Excerpt: Increasing reliance on autonomous systems requires confidence in the accuracies produced from computer vision classification algorithms. Computer vision (CV) for video classification provides phenomenal abilities, but it often suffers from “flickering” of results. Flickering occurs when the CV algorithm switches between declared classes over successive frames. Such behavior causes a loss of trust and confidence in their operations.

Time Domain Spectral Lidar Enabled By Cascaded Raman In A Hydrogen-Filled Transmitter, Richard K. Martin, Trevor L. Courtney, Arielle M. Adams, Daniel E. Leaird, Luke Ausley, Christian K. Keyser

Faculty Publications

We introduce what we believe to be novel spectral light detection and ranging (LiDAR) architectures that enable ultra-compact systems by a transition from spectral signal processing in space (gratings) to processing in time. The architectures leverage temporal dispersion and the unique spectro-temporal waveforms produced from the cascaded Raman scattering generated in the (H₂) filled hollow core fiber. The characterized Raman source yields as many as six Raman orders from 1.06-1.70 μm; their unique spectro-temporal waveforms are measured. System performance simulations based on measured Raman waveforms show that high accuracy measurement of range and reflectivity are possible with proper …

Limitations Of Beam-Control Compensation, Matthew Kalensky, Darren Getts, Matthias T. Banet, Derek J. Burrell, Milo W. Hyde, Mark F. Spencer

Faculty Publications

In this paper, we use wave-optics simulations to explore the limitations of beam-control compensation. We evaluate performance in terms of the normalized power in a diffraction-limited bucket for the cases of no beam-control compensation, perfect phase compensation, and perfect full-field compensation. From these results, we are able to arrive at the following conclusions: (1) without any form of beam-control compensation, performance begins to degrade when D/r₀ > 1; (2) with perfect phase compensation, performance begins to degrade when D/r₀ > 1 and (λ/r₀)/θ₀ > 1; and (3) with perfect full-field compensation, performance begins to degrade when D/r_{0 …}

Inferring Tlb Configuration With Performance Tools, Cristian Agredo, Tor J. Langehaug, Scott R. Graham

Faculty Publications

Modern computing systems are primarily designed for maximum performance, which inadvertently introduces vulnerabilities at the micro-architecture level. While cache side-channel analysis has received significant attention, other Central Processing Units (CPUs) components like the Translation Lookaside Buffer (TLB) can also be exploited to leak sensitive information. This paper focuses on the TLB, a micro-architecture component that is vulnerable to side-channel attacks. Despite the coarse granularity at the page level, advancements in tools and techniques have made TLB information leakage feasible. The primary goal of this study is not to demonstrate the potential for information leakage from the TLB but to establish …

Constraining Accreted Neutron Star Crust Shallow Heating With The Inferred Depth Of Carbon Ignition In X-Ray Superbursts, Zachary P. Meisel

Faculty Publications

Evidence has accumulated for an as-yet unaccounted for source of heat located at shallow depths within the accreted neutron star crust. However, the nature of this heat source is unknown. I demonstrate that the inferred depth of carbon ignition in X-ray superbursts can be used as an additional constraint for the magnitude and depth of shallow heating. The inferred shallow heating properties are relatively insensitive to the assumed crust composition and carbon fusion reaction rate. For low-accretion rates, the results are weakly dependent on the duration of the accretion outburst, so long as accretion has ensued for enough time to …

Global Empirical Model Of Sporadic-E Occurrence Rates, Eli V. Parsch, Anthony L. Franz, Eugene V. Dao, Dong L. Wu, Nimalan Swarnalingam, Cornelius C. J. H. Salinas, Daniel J. Emmons

Faculty Publications

Intense ionization enhancements in the Earth’s ionosphere, known as sporadic-E (E_s), can degrade and severely disrupt the propagation of radio signals. Although many previous studies have analyzed the characteristics and morphologies of sporadic-E, few efforts have attempted to model global E_s occurrence rates (ORs) at high time resolutions. This study develops a global empirical model of blanketing sporadic-E occurrence rates using a Karhunen–Loéve Expansion (KLE) of a global OR climatology built with Global Navigation Satellite System radio occultation (GNSS-RO) and ionosonde observations. Using an fbE ≥ threshold of 3 MHz, the model outputs a blanketing sporadic-E …

Adverse Childhood Experiences And Hiv-Related Stigma: A Quantitative Survey Of Tanzanian Men, June 2019, Amandeep Kaur, Monique J. Brown Ph.D., Mph, Geoffrey K. Kangogo, Xiaoming Li Ph.D., Ivan E. Teri, Gaspar Mbita, Aima A. Ahonkhai, Donaldson F. Conserve

Faculty Publications

Experiencing adverse childhood experiences (ACEs) may impact personal opinions, attitudes, and judgments, which can further result in HIV-related stigma. HIV-related stigma consequentially may impact HIV preventive measures such as HIV testing, pre-exposure prophylaxis uptake, and condom use. The extent to which ACEs influence HIV-related stigma perception has not been well studied. Therefore, the study aimed to examine the association between ACEs and perceived and interpersonal HIV-related stigma among Tanzanian HIV-negative men. Quantitative survey data were obtained from the Tanzania STEP (Self-Testing Education and Promotion) project established in four wards: Mabibo, Manzese, Tandale, and Mwanyanamala. A total of 507 men responded …

Evaluation And Lessons Learned From The Dissemination And Implementation Science Scholars Program In The National Cancer Prevention And Control Research Network, Daniela B. Friedman, Cam Escoffery, Elaine H. Morrato, Cynthia A. Thomson, Courtney N. Petagna, Freda Allyson Hucek, Mary Wangen, Aubrey Villalobos, James R. Hébert Scd, Samuel Noblet, Mayank Sakhuja, David O. Garcia, Jennifer L. Cruz, Stephanie B. Wheeler

Faculty Publications

Background:

The Centers for Disease Control and Prevention (CDC)-funded Cancer Prevention and Control Research Network (CPCRN) has been a leader in cancer-related dissemination & implementation (D&I) science. Given increased demand for D&I research, the CPCRN Scholars Program launched in 2021 to expand the number of practitioners, researchers, and trainees proficient in cancer D&I science methods. Methods:

The evaluation was informed by a logic model and data collected through electronic surveys. Through an application process (baseline survey), we assessed scholars’ competencies in D&I science domains/subdomains, collected demographic data, and asked scholars to share proposed project ideas. We distributed an exit survey …

Personalized Learning Path Problem Variations: Computational Complexity And Ai Approaches, Sean A. Mochocki, Mark Reith, Brett J. Borghetti, Gilbert L. Peterson, John Jasper, Laurence D. Merkle

Faculty Publications

E-learning courses often suffer from high dropout rates and low student satisfaction. One way to address this issue is to use personalized learning paths (PLPs), which are sequences of learning materials that meet the individual needs of students. However, creating PLPs is difficult and often involves combining knowledge graphs (KGs), student profiles, and learning materials. Researchers typically assume that the problem of creating PLPs belong to the nondeterministic polynomial (NP)-hard class of computational problems. However, previous research in this field has neither defined the different variations of the PLP problem nor formally established their computational complexity. Without clear definitions of …

Exploring The Association Between Parenting Stress And A Child’S Exposure To Positive Childhood Experiences (Pces), Elizabeth Crouch Ph.D., Elizabeth Radcliff, Monique J. Brown Ph.D., Mph, Peiyin Hung Ph.D

Faculty Publications

High levels of parenting stress, defined as a caregiver or parent feeling stress or aggravation from parenting, has been previously shown to be associated with an increased likelihood of neglect, child maltreatment, and household dysfunction: adverse childhood experiences (ACEs). Despite the potential mitigation of positive childhood experiences (PCEs) on ACEs, prior studies on the increased likelihood of a child experiencing ACEs due to parenting stress have left a critical question unanswered: whether high parenting stress may decrease a child’s likelihood of experiencing PCEs. We analyzed the 2019–2020 National Survey of Children’s Health to examine whether higher levels of parenting stress …

Predictability Limit Of The 2021 Pacific Northwest Heatwave From Deep‐Learning Sensitivity Analysis, P. Trent Vonich, Gregory J. Hakim

Faculty Publications

The traditional method for estimating weather forecast sensitivity to initial conditions uses adjoint models, which are limited to short lead times due to linearization around a control forecast. The advent of deep‐learning frameworks enables a new approach using backpropagation and gradient descent to iteratively optimize initial conditions, minimizing forecast errors. We apply this approach to the June 2021 Pacific Northwest heatwave using the GraphCast model, yielding over 90% reduction in 10‐day forecast errors over the Pacific Northwest. Similar improvements are found for Pangu‐Weather model forecasts initialized with the GraphCast‐derived optimal, suggesting that model error is an unimportant part of the …

Numerically Efficient Coherent Mode Representations For Partially Coherent Beams With Separable Phases, Milo W. Hyde, Carolina Rickenstorff

Faculty Publications

We present a method to numerically compute the coherent mode representations (CMRs) for partially coherent beams with separable phases. This special class of random light field has the ability to self-focus and is resistant to turbulence-induced degradation, making it potentially useful in applications such as optical communications. We validate our method by generating (in simulation) two such sources from the literature using their computed CMRs. Lastly, we conclude with a summary of our approach and a discussion of potential applications.

Social Isolation And Loneliness Prevention Among Rural Older Adults Aging-In-Place: A Needs Assessment, Jodi L. Southerland, Shimin Zheng, Kayla Dodson, Erin Mauck, Juanita-Dawne R. Bacsu, Monique J. Brown Ph.D., Mph, Jeremy Holloway, Steffi M. Kim, Ayse Malatyali, Matthew Lee Smith

Faculty Publications

Introduction: The adverse effects of social isolation and loneliness (SI/L) have been documented among older adults in rural communities and contribute to poor health outcomes, premature disability and mortality, and increased burden on the healthcare system. The identification of factors contributing to SI/L among older adults can build the foundation for rural policymakers and leaders to allocate resources and develop tailored strategies more efficiently. The purpose of this article is to describe findings from a needs assessment designed to understand local factors that contribute to SI/L among rural older adults in a county in Northeast Tennessee. Findings from the needs …

Distributed Software Build Assurance For Software Supply Chain Integrity, Ken Lew, Arijet Sarker, Simeon Wuthier, Jinoh Kim

Faculty Publications

Computing and networking are increasingly implemented in software. We design and build a software build assurance scheme detecting if there have been injections or modifications in the various steps in the software supply chain, including the source code, compiling, and distribution. Building on the reproducible build and software bill of materials (SBOM), our work is distinguished from previous research in assuring multiple software artifacts across the software supply chain. Reproducible build, in particular, enables our scheme, as our scheme requires the software materials/artifacts to be consistent across machines with the same operating system/specifications. Furthermore, we use blockchain to deliver the …

Closed-Loop Adaptive Optics In The Presence Of Speckle And Weak Scintillation, Derek J. Burrell, Mark F. Spencer, Ronald G. Driggers

Faculty Publications

In this paper, we show that speckle averaging helps to improve adaptive-optics (AO) performance in closed loop as a result of reduced measurement error associated with a Shack–Hartmann wavefront sensor (SHWFS); however, this reduction is rendered ineffective with increasing beacon anisoplanatism. We do so operating in a weak-scintillation regime, where the SHWFS offers robust performance, and using in-plane translation of the illuminated rough surface to accomplish frame-to-frame speckle diversity. Understanding these trade-space limitations is critical when performing AO with non-cooperative, extended-source beacons.

A Comparison Of Gaussian Processes And Polynomial Chaos Emulators In The Context Of Haemodynamic Pulse–Wave Propagation Modelling, L. Mihaela Paun, Mitchel J. Colebank, Dirk Husmeier

Faculty Publications

Computational modelling of the cardiovascular system is a promising future direction for patient-specific healthcare. However, the computational cost of these simulators is a bottleneck for their practical use in clinic for real-time digital twins. Emulation can overcome this, yet an extensive investigation into cardiovascular emulators is warranted. In this study, we emulate two one-dimensional haemodynamics models of the pulmonary circulation and compare two common emulation strategies: Gaussian processes (GPs) and polynomial chaos expansions (PCEs). We start by reducing the parameter space of the models through global sensitivity analysis, and then compare both emulation strategies using a multivariate, time-series output …

Examination Of Photoinduced Radicals In Two Crystal Forms Of Triphenylamine Bis-Urea Macrocycles, Md Faizul Islam, Gamage Isuri P. Wijesekera, Anmon J. Sindt, Mark D. Smith, Linda S. Shimizu

Faculty Publications

This study probes two solvates of triphenylamine (TPA) bis-urea macrocycle 1 and their activated structures to evaluate their maximum photoinduced radicals (PIRs), the subsequent decay of the radicals, and their regeneration. The hierarchical assembly of TPAs shows promise in stabilizing less substituted derivatives, potentially expanding the utility of TPAs that lack stabilizing para-substituents. Single crystal structure analysis reveals that host 1 adopts a planar conformation with the two ureas pointing in opposite directions when dimethoxyethane (DME) is encapsulated within the channel. Whereas previously, 1 adopted a bowl-shaped conformation with the two ureas pointing in the same direction (syn …