Physical Sciences and Mathematics Commons^™

Simulating Sub-Threshold Communication Channels Through Neurons, Richard Maina

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

Molecular Communication is an emerging paradigm with the potential to revolutionize the technology behind wearable and implantable devices and the broad range of functions they support, from tracking physical activity to medical diagnostics. This can be achieved through intra-body communication networks that take advantage of natural biological processes as a means of transmitting, propagating and receiving information. In this thesis we focus particularly on using the neuron as a means to facilitate information transfer for interconnected wearable or implantable devices through a technique known as sub-threshold electrical stimulation. We develop upon a prior work by introducing a linear model of …

Comparing Airborne Algorithms For Greenhouse Gas Flux Measurements Over The Alberta Oil Sands, Broghan M. Erland, Cristen Adams, Andrea Darlington, Mackenzie L. Smith, Andrew K. Thorpe, Gregory R. Wentworth, Steve Conley, John Liggio, Shao-Meng Li, Charles E. Miller, John A. Gamon

School of Natural Resources: Faculty Publications

To combat global warming, Canada has committed to reducing greenhouse gases to be (GHGs) 40 %–45 % below 2005 emission levels by 2025. Monitoring emissions and deriving accurate inventories are essential to reaching these goals. Airborne methods can provide regional and area source measurements with small error if ideal conditions for sampling are met. In this study, two airborne mass-balance box-flight algorithms were compared to assess the extent of their agreement and their performance under various conditions. The Scientific Aviation’s (SciAv) Gaussian algorithm and the Environment and Climate Change Canada’s top-down emission rate retrieval algorithm (TERRA) were applied to data …

Spatial Stream Modeling Of Louisiana Waterthrush (Parkesia Motacilla) Foraging Substrate And Aquatic Prey In A Watershed Undergoing Shale Gas Development, Mack W. Frantz, Petra B. Wood, Steven C. Latta

United States Geological Survey: Staff Publications

We demonstrate the use of spatial stream network models (SSNMs) to explore relationships between a semiaquatic bioindicator songbird, Louisiana Waterthrush (Parkesia motacilla), and stream monitoring and benthic macroinvertebrate data in an area undergoing shale gas development. SSNMs allowed us to account for spatial autocorrelation inherent to these environmental data types and stream properties that traditional modeling approaches cannot capture to elucidate factors that affect waterthrush foraging locations. We monitored waterthrush along 58.1 km of 1st- and 2nd-order headwater stream tributaries (n = 14) in northwestern West Virginia over a two year period (2013–2014), sampled benthic macroinvertebrates in waterthrush …

Spin-Neutral Tunneling Anomalous Hall Effect, Ding-Fu Shao, Shu-Hui Zhang, Rui-Chun Xiao, Zi-An Wang, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal

Department of Physics and Astronomy: Faculty Publications

Anomalous Hall effect (AHE) is a fundamental spin-dependent transport property that is widely used in spintronics. It is generally expected that currents carrying net spin polarization are required to drive the AHE. Here we demonstrate that, in contrast to this common expectation, a spin-neutral tunneling AHE (TAHE), i.e. a TAHE driven by spin-neutral currents, can be realized in an antiferromagnetic (AFM) tunnel junction where an AFM electrode with a non-spin-degenerate Fermi surface and a normal metal electrode are separated by a non-magnetic barrier with strong spin-orbit coupling (SOC). The symmetry mismatch between the AFM electrode and the SOC barrier results …

Optimising Response To An Introduction Of African Swine Fever In Wild Pigs, Kim M. Pepin, Vienna R. Brown, Anni Yang, James C. Beasley, Raoul Boughton, Kurt C. Vercauteren, Ryan S. Miller, Sarah N. Bevins

United States Department of Agriculture Wildlife Services: Staff Publications

African swine fever virus (ASFv) is a virulent pathogen that threatens domestic swine industries globally and persists in wild boar populations in some countries. Persistence in wild boar can challenge elimination and prevent disease-free status, making it necessary to address wild swine in proactive response plans. In the United States, invasive wild pigs are abundant and found across a wide range of ecological conditions that could drive different epidemiological dynamics among populations. Information on the size of the control areas required to rapidly eliminate the ASFv in wild pigs and how this area should change with management constraints and local …

Nmr And Metabolomics—A Roadmap For The Future, David S. Wishart, Leo L. Cheng, Valérie Copié, Arthur S. Edison, Hamid R. Eghbalnia, Jeffrey C. Hoch, Goncalo J. Gouveia, Wimal Pathmasiri, Robert Powers, Tracey B. Schock, Lloyd W. Sumner, Mario Uchimiya

Chemistry Department: Faculty Publications

Metabolomics investigates global metabolic alterations associated with chemical, biological, physiological, or pathological processes. These metabolic changes are measured with various analytical platforms including liquid chromatography-mass spectrometry (LC-MS), gas chromatographymass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). While LC-MS methods are becoming increasingly popular in the field of metabolomics (accounting for more than 70% of published metabolomics studies to date), there are considerable benefits and advantages to NMR-based methods for metabolomic studies. In fact, according to PubMed, more than 926 papers on NMR-based metabolomics were published in 2021—the most ever published in a given year. This suggests that NMR-based metabolomics …

Profiling A Community-Specific Function Landscape For Bacterial Peptides Through Protein-Level Meta-Assembly And Machine Learning, Mitra Vajjala, Brady Johnson, Lauren Kasparek, Michael Leuze, Qiuming Yao

School of Computing: Faculty Publications

Small proteins, encoded by small open reading frames, are only beginning to emerge with the current advancement of omics technology and bioinformatics. There is increasing evidence that small proteins play roles in diverse critical biological functions, such as adjusting cellular metabolism, regulating other protein activities, controlling cell cycles, and affecting disease physiology. In prokaryotes such as bacteria, the small proteins are largely unexplored for their sequence space and functional groups. For most bacterial species from a natural community, the sample cannot be easily isolated or cultured, and the bacterial peptides must be better characterized in a metagenomic manner. The bacterial …

Spatio-Temporal Models Of Infectious Disease With High Rates Of Asymptomatic Transmission, Aminur Rahman, Angela Peace, Ramesh Kesawan, Souparno Ghosh

Department of Statistics: Faculty Publications

The surprisingly mercurial Covid-19 pandemic has highlighted the need to not only accelerate research on infectious disease, but to also study them using novel techniques and perspectives. A major contributor to the dificulty of containing the current pandemic is due to the highly asymptomatic nature of the disease. In this investigation, we develop a modeling framework to study the spatio-temporal evolution of diseases with high rates of asymptomatic transmission, and we apply this framework to a hypothetical country with mathematically tractable geography; namely, square counties uniformly organized into a rectangle. We first derive a model for the temporal dynamics of …

Combining Solution Reuse And Bound Tightening For Efficient Analysis Of Evolving Systems, Clay Stevens, Hamid Bagheri

CSE Conference and Workshop Papers

Software engineers have long employed formal verification to ensure the safety and validity of their system designs. As the system changes—often via predictable, domain-specific operations—their models must also change, requiring system designers to repeatedly execute the same formal verification on similar system models. State-of-the-art formal verification techniques can be expensive at scale, the cost of which is multiplied by repeated analysis. This paper presents a novel analysis technique—implemented in a tool called SoRBoT—which can automatically determine domain-specific optimizations that can dramatically reduce the cost of repeatedly analyzing evolving systems. Different from all prior approaches, which focus on either tightening the …

Internal Model Control (Imc)-Based Active And Reactive Power Control Of Brushless Double-Fed Induction Generator With Notch Filter, Ahsanullah Memon, Mohd Wazir Bin Mustafa, Zohaib Hussain Laghari, Touqeer Ahmed Jumani, Waqas Anjum, Shafi Ullah, Muhammad Naveed Aman

School of Computing: Faculty Publications

The increase in demand for electricity and, in particular, green energy has put renewable energy systems at the focal point of energy policy worldwide. The higher reliability of brushless doubly fed induction generators (BDFIGs) makes them suitable for offshore and remote wind energy generation (WEG) applications. Besides, controlling the active and reactive powers in an electrical power system is critical for optimal voltage regulation, reduced power losses, and enhanced utilization of installed equipment. However, the existing literature on BDFIG’s active and reactive power control highlights the poor dynamic response and high transients with harmonic generation during inductive load insertion. It …

Amplification Of Black Vulture (Coragyps Atratus) Dna From Regurgitated Food Pellets, Daniel R. Taylor, Bryan M. Kluever, John S. Humphrey, Iona M. Hennessy, Amber Sutton, William E. Bruce, Antoinette J. Piaggio

United States Department of Agriculture Wildlife Services: Staff Publications

Studies that rely on noninvasive collection of DNA for birds often use feces or feathers. Some birds, such as vultures, regurgitate undigested matter in the form of pellets that are commonly found under roost sites. Our research demonstrates that regurgitated pellets are a viable, noninvasive source of DNA for molecular ecology studies of vultures. Our objectives were to amplify 5 microsatellite loci designed for distinguishing Turkey Vultures (Cathartes aura) and Black Vultures (Coragyps atratus) in a single, multiplexed PCR, and to determine how long the target nuclear DNA persists after a vulture pellet is regurgitated and …

Negative Photoresponse In Ti3C2TX Mxene Monolayers, Nataliia S. Vorobeva, Saman Bagheri, Angel Torres, Alexander Sinitskii

Chemistry Department: Faculty Publications

Two-dimensional transition metal carbides, nitrides, and carbonitrides, collectively known as MXenes, are finding numerous applications in many different areas, including optoelectronics and photonics, but there is limited information about their intrinsic photoresponse. In this study, we investigated the visible and near-infrared range photoresponse of Ti₃C₂T_x, the most popular MXene material to date. The electrical measurements were performed on devices based on individual monolayer Ti₃C₂T_x MXene flakes, which were characterized by a variety of microscopic and spectroscopic methods. For MXene devices with different electrode layouts, the current reproducibly decreased under …

Characterization Of Three-Dimensional Fractional Viscoelastic Models Through Complex Modulus Analysis And Polar Decomposition, Avradip Ghosh, Avinash Kumar Both, Chin Li Cheung

Chemistry Department: Faculty Publications

Soft materials such as gels, elastomers, and biological tissues have diverse applications in nature and technology due to their viscoelastic nature. These soft materials often exhibit complex rheology and display elastic and viscous characteristics when undergoing deformation. In recent years, fractional calculus has emerged as a promising tool to explain the viscoelastic behavior of soft materials. Scalar constants are primarily used to quantify viscoelastic elements such as springs and dashpots. However, in three-dimensional (3D) space, not all materials show the same elastic or viscoelastic properties in all directions, especially under elastic/viscoelastic wave propagation (or anisotropy). Though previously reported studies on …

Search For Flavor-Changing Neutral Current Interactions Of The Top Quark And Higgs Boson In Final States With Two Photons In Proton-Proton Collisions At √S =13 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb⁻¹. No significant excess above the background prediction is observed. Upper limits on the branching fractions (Ɓ) of the top quark decaying to a Higgs boson and an up (u) or charm …

Science Of The Total Environment, Benjamin Linhoff

United States Geological Survey: Staff Publications

Recently, the subsoils of ephemeral stream(arroyos) floodplains in the northern Chihuahuan Desert were discovered to contain large naturally occurring NO₃⁻ reservoirs (floodplain:~38,000 kg NO₃-N/ha; background:~60 kg NO₃-N/ha). These reservoirs may be mobilized through land use change or natural stream channel migration which makes differentiating between anthropogenic and natural groundwaterNO₃⁻sources challenging. In this study, the fate and sources of NO₃⁻ were investigated in an area with multiple NO₃⁻ sources such as accidental sewer line releases and sewage lagoons aswell as natural reservoirs of subsoil NO₃⁻. …

Multiplexed Monitoring Of Neurochemicals Via Electrografting- Enabled Site-Selective Functionalization Of Aptamers On Field-Effect Transistors, Zan Gao, Guangfu Wu, Yang Song, Huijie Li, Yuxuan Zhang, Michael J. Schneider, Yingqi Qiang, Jackson Kaszas, Zhengyan Weng, He Sun, Bryan D. Huey, Rebecca Lai, Yi Zhang

Chemistry Department: Faculty Publications

Neurochemical corelease has received much attention in understanding brain activity and cognition. Despite many attempts, the multiplexed monitoring of coreleased neurochemicals with spatiotemporal precision and minimal crosstalk using existing methods remains challenging. Here, we report a soft neural probe for multiplexed neurochemical monitoring via the electrografting-assisted site-selective functionalization of aptamers on graphene field-effect transistors (G-FETs). The neural probes possess excellent flexibility, ultralight mass (28 mg), and a nearly cellular-scale dimension of 50 μm × 50 μm for each G-FET. As a demonstration, we show that G-FETs with electrochemically grafted molecular linkers (−COOH or −NH2) and specific aptamers can be used …

Explosive Spontaneous Emulsification, Xuefei Wu, Gautam Bordia, Robert Streubel, Jaffar Hasnain, Ahmad K. Omar, Phillip L. Geissler, Dong Wang, Han Xue, Jianjun Wang, Thomas P. Russell

Department of Physics and Astronomy: Faculty Publications

Spontaneous emulsification, resulting from the assembly and accumulation of surfactants at liquid-liquid interfaces, is an interfacial instability where microdroplets are generated and diffusively spread from the interface until complete emulsification. Here, we show that an external magnetic field can modulate the assembly of paramagnetic nanoparticle surfactants (NPSs) at liquid-liquid interfaces and trigger an oversaturation in the areal density of the NPSs at the interface, as evidenced by the reduction in the interfacial tension, γ, and corroborated with a magnetostatic continuum theory. Despite the significant reduction in γ, the presence of the magnetic field does not cause stable interfaces to become …

Seasonal Climatic Niche And Migration Movements Of Double-Crested Cormorants, D. Tommy King, Guiming Wang, Fred L. Cunningham

United States Department of Agriculture Wildlife Services: Staff Publications

Avian migrants are challenged by seasonal adverse climatic conditions and energetic costs of long-distance flying. Migratory birds may track or switch seasonal climatic niche between the breeding and non-breeding grounds. Satellite tracking enables avian ecologists to investigate seasonal climatic niche and circannual movement patterns of migratory birds. The Double-crested Cormorant (Nannopterum auritum, hereafter cormorant) wintering in the Gulf of Mexico (GOM) migrates to the Northern Great Plains and Great Lakes and is of economic importance because of its impacts on aquaculture. We tested the climatic niche switching hypothesis that cormorants would switch climatic niche between summer and winter …

Nabat Ml: Utilizing Deep Learning To Enable Crowdsourced Development Of Automated, Scalable Solutions For Documenting North American Bat Populations, Ali Khalighifar, Benjamin S. Gotthold, Erin Adams, Jenny Barnett, Laura O. Beard, Eric R. Britzke, Paul A. Burger, Kimberly Chase, Zackary Cordes, Paul M. Cryan, Emily Emily, Christopher T. Fill, Scott E. Gibson, G. Scott Haulton, Kathryn M. Irvine, Lara S. Katz, William L. Kendall, Christen A. Long, Oisin Mac Aodha, Tessa Mcburney, Sara Mccarthy, Matthew W. Mckown, Joy O'Keefe, Lucy D. Patterson, Kristopher A. Pitcher, Matthew Rustand, Jordi L. Segers, Kyle Seppanen, Jeremy L. Siemers, Christian Stratton, Bethany R. Straw, Theodore J. Weller, Brian E. Reichert

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

1. Bats play crucial ecological roles and provide valuable ecosystem services, yet many populations face serious threats from various ecological disturbances. The North American Bat Monitoring Program (NABat) aims to use its technology infrastructure to assess status and trends of bat populations, while developing innovative and community-driven conservation solutions.

2. Here, we present NABat ML, an automated machine-learning algorithm that improves the scalability and scientific transparency of NABat acoustic monitoring. This model combines signal processing techniques and convolutional neural networks (CNNs) to detect and classify recorded bat echolocation calls. We developed our CNN model with internet-based computing resources (‘cloud environment’), and …

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Consemblex: A Consensus-Based Transcriptome Assembly Approach That Extends Consemble And Improves Transcriptome Assembly, Richard Mwaba

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

An accurate transcriptome is essential to understanding biological systems enabling omics analyses such as gene expression, gene discovery, and gene-regulatory network construction. However, assembling an accurate transcriptome is challenging, especially for organisms without adequate reference genomes or transcriptomes. While several methods for transcriptome assembly with different approaches exist, it is still difficult to establish the most accurate methods. This thesis explores the different transcriptome assembly methods and compares their performances using simulated benchmark transcriptomes with varying complexity. We also introduce ConSemblEX to improve a consensus-based ensemble transcriptome assembler, ConSemble, in three main areas: we provide the ability to use any …

Many Cliques In Bounded-Degree Hypergraphs, Rachel Kirsch, J. Radcliffe

Department of Mathematics: Faculty Publications

Recently Chase determined the maximum possible number of cliques of size t in a graph on n vertices with given maximum degree. Soon afterward, Chakraborti and Chen answered the version of this question in which we ask that the graph have m edges and fixed maximum degree (without imposing any constraint on the number of vertices). In this paper we address these problems on hypergraphs. For s-graphs with s ≥ 3 a number of issues arise that do not appear in the graph case. For instance, for general s-graphs we can assign degrees to any i-subset of the vertex set …

Probing Charm Quark Dynamics Via Multiparticle Correlations In Pb-Pb Collisions At √SNn =5.02 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

Multiparticle azimuthal correlations of prompt D⁰ mesons are measured in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of √^sNN = 5.02 TeV. For the first time, a four-particle cumulant method is used to extract the second Fourier coefficient of the azimuthal distribution (ν₂) of D⁰ mesons as a function of event centrality and the D⁰ transverse momentum. The ratios of the four-particle v₂ values to previously measured two-particle cumulant results provide direct experimental access to event-by-event fluctuations of charm quark azimuthal anisotropies. These ratios are also found to be comparable to …

Asymmetric Control Of Light At The Nanoscale, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

Breaking reciprocity at the nanoscale can produce directional formation of images due to the asymmetric nonlinear optical response of subwavelength anisotropic resonators. The self-induced passive non-reciprocity has advantages compared to magnet or time modulation approaches and may impact both classical and quantum photonics.

Reply To Response By Fbi Laboratory Filed In Illinois V. Winfield And Affidavit By Biederman Et Al. (2022) Filed In Us V. Kaevon Sutton (2018 Cf1 009709), Susan Vanderplas, Kori Khan, Heike Hofmann, Alicia Carriquiry

Department of Statistics: Faculty Publications

1 Preliminaries

1.1 Scope

The aim of this document is to respond to issues raised in Federal Bureau of Investigation¹ and Alex Biedermann, Bruce Budowle & Christophe Champod.²

1.2 Conflict of Interest

We are statisticians employed at public institutions of higher education (Iowa State University and University of Nebraska, Lincoln) and have not been paid for our time or expertise when preparing either this response or the original affidavit.³ We provide this information as a public service and as scientists and researchers in this area.

1.3 Organization

The rest of the document precedes as follows: we begin …

Solar Radiation And Soil Moisture Drive Tropical Forest Understory Responses To Experimental And Natural Hurricanes, J. Aaron Hogan, Joanne M. Sharpe, Ashley Van Beusekom, Sarah Stankavich, Samuel Matta Carmona, John E. Bithorn, Jamarys Torres-Díaz, Grizelle González, Jess K. Zimmerman, Aaron B. Shiels

United States Department of Agriculture Wildlife Services: Staff Publications

Tropical forest understory regeneration occurs rapidly after disturbance with compositional trajectories that depend on species availability and environmental conditions. To predict future tropical forest regeneration dynamics, we need a deeper understanding of how pulse disturbance events, like hurricanes, interact with environmental variability to affect understory demography and composition. We examined fern and sapling mortality, recruitment, and community composition in relation to solar radiation and soil moisture using 17 years of forest dynamics data (2003–2019) from the Canopy Trimming Experiment in the Luquillo Experimental Forest, Puerto Rico. Solar radiation increased 150% and soil moisture increased 40% following canopy trimming of experimental …

Comparative Susceptibility Of Eastern Cottontails And New Zealand White Rabbits To Classical Rabbit Haemorrhagic Disease Virus (Rhdv) And Rhdv2, Fawzi Mohamed, Thomas Gidlewski, Mary L. Berninger, Heather M. Petrowski, Alexa J. Bracht, Carla Bravo De Rueda, Roger W. Barrette, Meredith Grady, Emily S. O'Hearn, Charles E. Lewis, Karen E. Moran, Tracy L. Sturgill, Lorenzo Capucci, J. Jeffrey Root

United States Department of Agriculture Wildlife Services: Staff Publications

Rabbit haemorrhagic disease virus (RHDV) is associated with high morbidity and mortality in the European rabbit (Oryctolagus cuniculus). In 2010, a genetically distinct RHDV named RHDV2 emerged in Europe and spread to many other regions, including North America in 2016. Prior to this study it was unknown if eastern cottontails (ECT(s); Sylvilagus floridanus), one of the most common wild lagomorphs in the United States, were susceptible to RHDV2. In this study, 10 wild-caught ECTs and 10 New Zealand white rabbits (NZWR(s); O. cuniculus) were each inoculated orally with either RHDV (RHDVa/GI.1a; n = 5 per species) or RHDV2 (a recombinant …

Ultrafast Electron Diffraction: Visualizing Dynamic States Of Matter, D. Filipetto, P. Musumed, R. K. Li, B. J. Siwick, M. R. Otto, Martin Centurion, J. P.F. Nunes

Martin Centurion Publications

Since the discovery of electron-wave duality, electron scattering instrumentation has developed into a powerful array of techniques for revealing the atomic structure of matter. Beyond detecting local lattice variations in equilibrium structures with the highest possible spatial resolution, recent research efforts have been directed towards the long sought-after dream of visualizing the dynamic evolution of matter in real-time. The atomic behavior at ultrafast timescales carries critical information on phase transition and chemical reaction dynamics, the coupling of electronic and nuclear degrees of freedom in materials and molecules, the correlation between structure, function and previously hidden metastable or nonequilibrium states of …

Genomic Prediction Accuracy Of Stripe Rust In Six Spring Wheat Populations By Modeling Genotype By Environment Interaction, Kassa Semagn, Muhammad Iqbal, Diego Jarquin, Harpinder Randhawa, Reem Aboukhaddour, Reka Howard, Izabela Ciechanowska, Momna Farzand, Raman Dhariwal, Colin W. Hiebert, Amidou N’Diaye, Curtis Pozniak, Dean Spaner

Department of Statistics: Faculty Publications

Some previous studies have assessed the predictive ability of genome-wide selection on stripe (yellow) rust resistance in wheat, but the effect of genotype by environment interaction (GEI) in prediction accuracies has not been well studied in diverse genetic backgrounds. Here, we compared the predictive ability of a model based on phenotypic data only (M1), the main effect of phenotype and molecular markers (M2), and a model that incorporated GEI (M3) using three cross-validations (CV1, CV2, and CV0) scenarios of interest to breeders in six spring wheat populations. Each population was evaluated at three to eight field nurseries and genotyped with …

Ultra-High Carrier Mobilities In Ferroelectric Domain Wall Corbino Cones At Room Temperature, Conor J. Mccluskey, Matthew G. Colbear, James P.V. Mcconville, Shane J. Mccartan, Jesi R. Maguire, Michele Conroy, Kalani Moore, Alan Harvey, Felix Trier, Ursel Bangert, Alexei Gruverman, Manuel Bibes, Amit Kumar, Raymong G.P. Mcquaid, J. Marty Gregg

Alexei Gruverman Publications

Recently, electrically conducting heterointerfaces between dissimilar band-insulators (such as lanthanum aluminate and strontium titanate) have attracted considerable research interest. Charge transport has been thoroughly explored and fundamental aspects of conduction firmly established. Perhaps surprisingly, similar insights into conceptually much simpler conducting homointerfaces, such as the domain walls that separate regions of different orientations of electrical polarisation within the same ferroelectric band-insulator, are not nearly so well-developed. Addressing this disparity, we herein report magnetoresistance in approximately conical 180° charged domain walls, which occur in partially switched ferroelectric thin film single crystal lithium niobate. This system is ideal for such measurements: firstly, …

Asymmetrical Spectral Continuum Between Anti-Stokes And Stokes Scattering Revealed In Low-Frequency Surface-Enhanced Raman Spectroscopy, Shuo Sun, Dhanusha T.N. Rathnayake, Yinsheng Guo

Chemistry Department: Faculty Publications

An asymmetrical spectral continuum is observed in low-frequency surface-enhanced Raman spectroscopy (LF-SERS) in the terahertz (THz) region. This background continuum appears as a flat baseline in the Stokes side and a slope in the anti-Stokes side. Analysis shows this asymmetry originates from the different scaling of anti-Stokes and Stokes scattering with respect to the Bose−Einstein distribution. Such asymmetry is readily visible, under room temperature, in the low-frequency THz spectral range. Accounting for this spectral intensity asymmetry reveals the intrinsic continuum background of electronic origin, differing from local normal modes and collective relaxational motions. We also describe a numerical method, independent …