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2022

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Articles 17731 - 17760 of 18217

Full-Text Articles in Physical Sciences and Mathematics

Enterprise Resource Planning Implementation Strategies In Small- And Medium-Sized Manufacturing Enterprises, Tatianna Gilliam Jan 2022

Enterprise Resource Planning Implementation Strategies In Small- And Medium-Sized Manufacturing Enterprises, Tatianna Gilliam

Walden Dissertations and Doctoral Studies

The difficulty SME leaders of manufacturing firms experience in the executing of enterprise resource planning (ERP) systems threatens the longevity of innovative change within firms seeking to adopt ERP systems. Grounded in the diffusion of innovation theory, the purpose of this multiple case study was to examine critical success factors used to successfully implement ERP systems. The participants were four ERP business leaders of small to medium size manufacturing firms based on the east and west coasts of the United States. Data were collected using semistructured online interviews and a review of company documents. Through thematic analysis, five themes were …


Strategies That Improve Ux (User Experience) Design Through Product Innovation, Jibing Zhao Jan 2022

Strategies That Improve Ux (User Experience) Design Through Product Innovation, Jibing Zhao

Walden Dissertations and Doctoral Studies

User Experience (UX) design improvement can alter business results. Information technology (IT) company leaders are concerned with UX design improvement, as it is the number one indication of product innovation success and user satisfaction. Grounded in Christensen’s disruptive innovation theory, the purpose of the qualitative single case study was to explore strategies IT company leaders and UX designers used to identify critical UX design elements that lead to improved product innovations. The participants were five IT company leaders and a focus group of four UX designers employed by a sizeable telecom organization in Beijing, China. The data were collected from …


Reinforcement Learning: Low Discrepancy Action Selection For Continuous States And Actions, Jedidiah Lindborg Jan 2022

Reinforcement Learning: Low Discrepancy Action Selection For Continuous States And Actions, Jedidiah Lindborg

College of Graduate Studies: Theses & Dissertations

In reinforcement learning the process of selecting an action during the exploration or exploitation stage is difficult to optimize. The purpose of this thesis is to create an action selection process for an agent by employing a low discrepancy action selection (LDAS) method. This should allow the agent to quickly determine the utility of its actions by prioritizing actions that are dissimilar to ones that it has already picked. In this way the learning process should be faster for the agent and result in more optimal policies.


Eeg Signals Classification Using Lstm-Based Models And Majority Logic, James A. Orgeron Jan 2022

Eeg Signals Classification Using Lstm-Based Models And Majority Logic, James A. Orgeron

College of Graduate Studies: Theses & Dissertations

The study of elecroencephalograms (EEGs) has gained enormous interest in the last decade with the increase of computational power and availability of EEG signals collected from various human activities or produced during medical tests. The applicability of analyzing EEG signals ranges from helping impaired people communicate or move (using appropriate medical equipment) to understanding people's feelings and detecting diseases.

We proposed new methodology and models for analyzing and classifying EEG signals collected from individuals observing visual stimuli. Our models rely on powerful Long-Short Term Memory (LSTM) Neural Network models, which are currently the state of the art models for performing …


Characterization Of Functionalized Carbon Nanotubes And Polystyrene/Cnt Composites Prepared With Microwave-Induced Polymerization, Allen Hulette Jan 2022

Characterization Of Functionalized Carbon Nanotubes And Polystyrene/Cnt Composites Prepared With Microwave-Induced Polymerization, Allen Hulette

College of Graduate Studies: Theses & Dissertations

The use of carbon nanotubes in polymer composites can increase the mechanical properties of the resulting product. Carbon nanotubes are known to have chemical interactions that make them attracted to one another and fall out of solution. To reduce this agglomeration and disperse the mechanical properties throughout the composite, functional groups are covalently added to the carbon nanotubes. Another known property of carbon nanotubes is their ability to absorb microwaves and convert it into other forms of energy. This research investigates the effects of carbon nanotube absorption of microwaves and initiation of styrene monomer polymerization. Grignard reactions are used to …


Toward Novel Optical Functionalities Through Intelligent Photonic Structure Design, Robert J. Williamson Jan 2022

Toward Novel Optical Functionalities Through Intelligent Photonic Structure Design, Robert J. Williamson

College of Graduate Studies: Theses & Dissertations

Photonic Metamaterials is a branch of electromagnetism that has been of great interest in recent years. This is further enhanced by the introduction of micro- and nanofabrication methods capable of producing metamaterial structures with which it is possible to create specific optical phenomena. The study of iso-frequency k-surfaces is of importance when discussing optical interactions with media. Previous research found evidence of materials exhibiting k-surfaces of bi-hyperbolic nature, though they failed to find any further hyperboloid dispersions. In this thesis we describe the k-surface topologies and including tri- and tetra-hyperbolic as well as analyze the polariton-interactions that cause these hyperbolic …


Developing And Validating A Machine Learning-Based Student Attentiveness Tracking System, Andrew L. Sanders Jan 2022

Developing And Validating A Machine Learning-Based Student Attentiveness Tracking System, Andrew L. Sanders

College of Graduate Studies: Theses & Dissertations

Academic instructors and institutions desire the ability to accurately and autonomously measure the attentiveness of students in the classroom. Generally, college departments use unreliable direct communication from students (i.e. emails, phone calls), distracting and Hawthorne effect-inducing observational sit-ins, and end-of-semester surveys to collect feedback regarding their courses. Each of these methods of collecting feedback is useful but does not provide automatic feedback regarding the pace and direction of lectures. Young et al. discuss that attention levels during passive classroom lectures generally drop after about ten to thirty minutes and can be restored to normal levels with regular breaks, novel activities, …


Non-Inferiority Testing: Kernel Estimation And Overlap Measure, Larie C. Ward Jan 2022

Non-Inferiority Testing: Kernel Estimation And Overlap Measure, Larie C. Ward

College of Graduate Studies: Theses & Dissertations

In non-inferiority testing, the decision of whether a proposed treatment is non-inferior to a reference treatment depends on model assumptions and choices of acceptable tolerance limits. Here, we consider a method that employs kernels to estimate the probability density functions of both the experimental and reference populations from two independent samples. Based on these densities, we introduce a quantity called the overlap coefficient or overlap measure. A bootstrap technique is helpful in exploring the distribution and variance empirically. We derive the distribution of this measure and define a hypothesis test that can be applied to the non-inferiority setting under some …


Synthesis Of Functionalized Aromatic Heterocyclic Compounds And Its Applications In Organized Self-Assemblies, Emmanuel T. Fasusi Jan 2022

Synthesis Of Functionalized Aromatic Heterocyclic Compounds And Its Applications In Organized Self-Assemblies, Emmanuel T. Fasusi

College of Graduate Studies: Theses & Dissertations

1,2,3-triazoles due to their structure, possess good optical properties and are capable of molecular recognition by their supramolecular capabilities of utilizing weak forces of interaction (such as hydrogen bonding, dipole interaction) in establishing a close association with targets. They are easy to synthesize, which opened the opportunity for a wide pharmaceutical application, mostly as pharmacological scaffolds. However, challenges such as poor water solubility, inefficient drug delivery and increased toxicities due to frequent dosing of drugs are commonly faced which reduces the efficacy of the drugs. It is therefore important to have “delivery vehicles” which could help transport the drugs to …


License Plate Image Quality Enhancement Utilizing Super Resolution Generative Adversarial Networks, Mark Moelter Jan 2022

License Plate Image Quality Enhancement Utilizing Super Resolution Generative Adversarial Networks, Mark Moelter

College of Graduate Studies: Theses & Dissertations

This thesis focuses primarily on enhancing the image quality of blurred license plates through the use of Super-Resolution Generative Adversarial Networks (SRGANs) [1]. We propose a synthetic dataset with SRGAN model to promote blurred image quality enhancement, and allow for model evaluation on a multitude of image input and output size combinations. SRGAN is mainly used for low-resolution image enhancement, but by heavily blurring the input images, the model is tested on its ability to blindly deblur and upsample images to the desired super-resolution (SR) size. The model enhances the image quality to nearly that of the reference images. The …


Synthesis And Characterization Of Multimetallic Clusters Featuring Iron, Cobalt, And 2,6-Bis(Trialkylsilylamino)Pyridines, Lynn Nguyen Jan 2022

Synthesis And Characterization Of Multimetallic Clusters Featuring Iron, Cobalt, And 2,6-Bis(Trialkylsilylamino)Pyridines, Lynn Nguyen

College of Graduate Studies: Theses & Dissertations

Extended metal atom chain (EMAC) complexes are multimetallic complexes of three or more metals, often containing M-M bonds, with the metal ions arranged linearly. These complexes have significant potential as molecular wires. They can elicit unique physical properties and reactivities, sometimes a result of direct magnetic exchange between metal centers, especially when incorporating first row transition metals. The synthesis of the first linear, triiron (II) complex with 2,6-bis[(trimethylsilyl)amino]pyridine (H2LMe) featuring Fe-Fe bonding from our group, Fe3LMe3, motivated the expansion of linear multimetallic EMAC complexes with Fe and Co, incorporating M-M bonds. …


Cryptography Through The Lens Of Group Theory, Dawson M. Shores Jan 2022

Cryptography Through The Lens Of Group Theory, Dawson M. Shores

College of Graduate Studies: Theses & Dissertations

Cryptography has been around for many years, and mathematics has been around even longer. When the two subjects were combined, however, both the improvements and attacks on cryptography were prevalent. This paper introduces and performs a comparative analysis of two versions of the ElGamal cryptosystem, both of which use the specific field of mathematics known as group theory.


Evaluation Of Tidal Fresh Forest Distributions And Tropical Storm Impacts Using Sentinel-2 Msi Imagery, Galen Costomiris Jan 2022

Evaluation Of Tidal Fresh Forest Distributions And Tropical Storm Impacts Using Sentinel-2 Msi Imagery, Galen Costomiris

College of Graduate Studies: Theses & Dissertations

Situated in the transitional zone between non-tidal forests upstream and tidal fresh marshes downstream, tidal fresh forests occupy a unique and increasingly precarious habitat. The threat of intensifying anthropogenic climate change, compounded by the effects of historical logging and drainage alterations, could reduce the extent of this valuable ecosystem. The overall goals of this project were to identify forest communities present in the Altamaha tidal fresh forest; develop satellite imagery-based classifications of tidal fresh forest and tidal marsh vegetation along the Altamaha River, Georgia; and to quantify changes in vegetation distribution in the aftermath of hurricanes Matthew and Irma. Based …


Biomimetic Synthesis Of Palladium Nanoparticles For Catalytic Application, Emily A. Groover Jan 2022

Biomimetic Synthesis Of Palladium Nanoparticles For Catalytic Application, Emily A. Groover

College of Graduate Studies: Theses & Dissertations

The synthesis of palladium nanoparticles (Pd NPs) using materials-directed peptides is a novel, nontoxic approach which exerts a high level of control over the particle size and shape. This biomimetic technique is environmentally benign, featuring nonhazardous ligands and ambient conditions. Nanoparticles are extremely reactive catalysts, boasting a large surface-to-volume ratio when compared to their bulk counterparts. The rational design of these nanoparticles using peptides has been very successful in aqueous environments, but no research has been done to apply it in organic systems. As such, the biomimetic synthesis of Pd NPs in an organic system is here investigated, with ethanol …


Performance Of Black Soldier Fly Frass Fertiliser On Maize (Zea Mays L.) Growth, Yield, Nutritional Quality, And Economic Returns, C. M. Tanga, D. Beesigamukama, M. Kassie, P. J. Egonyu, Changeh J. Ghemoh, Kiatoko Nkoba, S. Subramanian, A. O. Anyega, S. Ekesi Jan 2022

Performance Of Black Soldier Fly Frass Fertiliser On Maize (Zea Mays L.) Growth, Yield, Nutritional Quality, And Economic Returns, C. M. Tanga, D. Beesigamukama, M. Kassie, P. J. Egonyu, Changeh J. Ghemoh, Kiatoko Nkoba, S. Subramanian, A. O. Anyega, S. Ekesi

All Peer-Reviewed Publications

Although the black soldier fly frass fertiliser (BSFFF) is globally recognised as a promising and potential high-quality organic fertiliser, there is inadequate information on its impact on the growth performance and nutritional status of maize. Furthermore, no information exist on their combination with mineral fertiliser (NPK) as well as economic impact on maize production. This study evaluated the comparative impact of BSFFF, NPK and commercial organic fertiliser (Evergrow®) on growth, nitrogen use efficiency, yield, nutritional quality, and profitability of maize under greenhouse conditions. The treatments included: (1) sole application of BSFFF, conventional compost of brewers’ spent grain (BSG), Evergrow, and …


Nitrogen Use Efficiency Trends For Sustainable Crop Productivity In Lake Victoria Basin: Smallholder Farmers' Perspectives On Nitrogen Cycling, Winnie Ntinyari, Joseph Gweyi-Onyango, Mekonnen Giweta, Benson Mochoge, James Mutegi, Generose Nziguheba, Cargele Masso Jan 2022

Nitrogen Use Efficiency Trends For Sustainable Crop Productivity In Lake Victoria Basin: Smallholder Farmers' Perspectives On Nitrogen Cycling, Winnie Ntinyari, Joseph Gweyi-Onyango, Mekonnen Giweta, Benson Mochoge, James Mutegi, Generose Nziguheba, Cargele Masso

All Peer-Reviewed Publications

Nitrogen Use Efficiency (NUE) is one of the established metrics for benchmarking management of Nitrogen (N) in various systems. Numerous approaches to calculateNUEexist, making it difficult to compare the performances of systems depending on the methodology used. This study adopted the conceptualized framework by European Union Nitrogen Expert Panel (EUNEP) to calculateNUE values for cereal crops to determine future trends for the first time in the Lake Victoria region. Data were collected through in-person interviews among maize and rice smallholder farmers within the Lake Victoria region. Atotal of 293 observations were recorded. Collected data on yield andNfertilizer were used to …


Inter-Population Variation And Phenotypic Plasticity In Kairomone Use By A Poly-Specialist Spider-Eating Predator, Ana M. Cerveira, Robert R. Jackson Jan 2022

Inter-Population Variation And Phenotypic Plasticity In Kairomone Use By A Poly-Specialist Spider-Eating Predator, Ana M. Cerveira, Robert R. Jackson

All Peer-Reviewed Publications

Previous research on Cyrba algerina (Araneae, Salticidae) has shown this jumping spider expresses predatory specialisation with respect to spiders as prey as well as inter-population variation in responsiveness to prey-spider odour. However, this earlier research pertained to a single prey species (Oecobius machadoi) and only field-collected C. algerina individuals were tested. Here we extend the previous research by using laboratory-reared, as well as field-collected, individuals of C. algerina and also by using another prey-spider species, Zelotes thorelli, as well as O. machadoi. Two localities in Portugal are considered, Sintra where C. algerina and both prey species are abundant and Tavira …


Defi Governance And Decision-Making On Blockchain, Hassan Hamid Ekal, Shams N. Abdul-Wahab Jan 2022

Defi Governance And Decision-Making On Blockchain, Hassan Hamid Ekal, Shams N. Abdul-Wahab

Mesopotamian Journal of Computer Science

This research paper explores the concept of Decentralized Finance (DeFi) and the importance of governance and decision-making in DeFi platforms. The paper reviews the literature on traditional finance governance models and blockchain-based governance mechanisms in DeFi platforms, and discusses the challenges and opportunities in designing decentralized governance models for DeFi platforms. The research question is "What are the challenges and opportunities in designing decentralized governance models for DeFi platforms?" and the study objectives are to review the literature on traditional finance governance models, analyze blockchain-based governance mechanisms in DeFi platforms, and discuss the challenges and opportunities in designing decentralized governance …


Drivers And Challenges Of Wearable Devices Use: Content Analysis Of Online Users Reviews, Ahmed El Noshokaty, Omar El-Gayar, Abdullah Wahbeh, Mohammad A. Al-Ramahi, Tareq Nasralah Jan 2022

Drivers And Challenges Of Wearable Devices Use: Content Analysis Of Online Users Reviews, Ahmed El Noshokaty, Omar El-Gayar, Abdullah Wahbeh, Mohammad A. Al-Ramahi, Tareq Nasralah

Computer Information Systems Faculty Publications (Archived)

With recent advancements in wearable device technologies, there is still a need to investigate drivers and challenges associated with the use of these devices. Following a content analysis approach, this study leverages recent “found large-scale” data to better understand the drivers and challenges that affect the adoption and use of such devices. Analyzing a total of 16,717 online reviews about wearable devices, the findings emphasized the importance of various functionalities (perceived usefulness), appeal, and a number of device design features as the most prominent drivers, while concerns about quality, credibility, and perceived value as potential challenges to wearable adoption and …


Red Spruce Ecological Sites, Ecological States, And Restoration Pathways Quantified Through Soil Organic Carbon, James Edward Leonard Jan 2022

Red Spruce Ecological Sites, Ecological States, And Restoration Pathways Quantified Through Soil Organic Carbon, James Edward Leonard

Graduate Theses, Dissertations, and Problem Reports (ETD)

Tools used by agencies and organizations like the Forest Service (FS), the Natural Resource Conservation Service (NRCS), the Nature Conservancy (TNC), and the Central Appalachian Spruce Restoration Initiative (CASRI) to help guide red spruce (Picea rubens) ecosystem restoration within Central Appalachia could better address outcomes from management practices implemented in terms of soil organic carbon (SOC) stock changes. These high-elevation landscapes have a natural capacity to produce diverse ecosystem services that affect humans, animals, and plants alike. Ecological site descriptions (ESD) are an important tool used to restore impacted landscapes and provide detailed management prescriptions specific to red spruce ecological …


Regional Correlation And Depositional History Using Well Log And Core Data Of The Geneseo-Burket From The Poseidon 8m Well, Westmoreland County Pa, Usa, Spencer Leonard Williams Jr. Jan 2022

Regional Correlation And Depositional History Using Well Log And Core Data Of The Geneseo-Burket From The Poseidon 8m Well, Westmoreland County Pa, Usa, Spencer Leonard Williams Jr.

Graduate Theses, Dissertations, and Problem Reports (ETD)

Abstract

Regional Correlation and Depositional History using Well Log and Core Data of the Geneseo-Burket from the Poseidon 8M Well, Westmoreland County PA, USA



Spencer Williams

Natural gas producers have invested billions of dollars in Pennsylvania and West Virginia to establish significant gas production from the Devonian Marcellus Shale and the deeper Ordovician Utica-Point Pleasant interval. In addition, commercial gas production has been reported from several other Devonian shale units in the Appalachian region, including the Rhinestreet, Levanna, and Geneseo-Burket. The Marcellus Shale is the largest natural gas play in the United States. The Marcellus is located directly under the …


Using Drones To Evaluate Revegetation Success On Natural Gas Pipelines, Anthony Nelson Mesa Jan 2022

Using Drones To Evaluate Revegetation Success On Natural Gas Pipelines, Anthony Nelson Mesa

Graduate Theses, Dissertations, and Problem Reports (ETD)

The Appalachian region of the United States has significant growth in the production of natural gas. Developing the infrastructure required for this resource creates significant disturbances across the landscape, as both well pads and transportation pipelines must be created in this mountainous terrain. Midstream infrastructure, which includes pipeline rights-of-way and associated infrastructure, can cause significant environmental degradation, especially in the form of sedimentation. The introduction of this non-point source pollutant can be detrimental to freshwater ecosystems found throughout this region. This ecological risk has necessitated the enactment of regulations related to midstream infrastructure development. Weekly, inspectors travel afoot along pipeline …


Effect Of Connection State & Transport/Application Protocol On The Machine Learning Outlier Detection Of Network Intrusions, George Yuchi, Torrey J. Wagner, Paul Auclair, Brent T. Langhals Jan 2022

Effect Of Connection State & Transport/Application Protocol On The Machine Learning Outlier Detection Of Network Intrusions, George Yuchi, Torrey J. Wagner, Paul Auclair, Brent T. Langhals

Faculty Publications

The majority of cyber infiltration & exfiltration intrusions leave a network footprint, and due to the multi-faceted nature of detecting network intrusions, it is often difficult to detect. In this work a Zeek-processed PCAP dataset containing the metadata of 36,667 network packets was modeled with several machine learning algorithms to classify normal vs. anomalous network activity. Principal component analysis with a 10% contamination factor was used to identify anomalous behavior. Models were created using recursive feature elimination on logistic regression and XGBClassifier algorithms, and also using Bayesian and bandit optimization of neural network hyperparameters. These models were trained on a …


Electronic Reconstruction At The Polar (111)-Oriented Oxide Interface, S. Ryu, H. Zhou, Tula R. Paudel, Neil Campbell, J. Podkaminer, C. W. Bark, T. Hernandez, D. D. Fong, Y. Zhang, L. Xie, X. Q. Pan, Evgeny Y. Tsymbal, M. S. Rzchowski, Chang-Beom Eom Jan 2022

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

Evgeny Tsymbal Publications

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


A Pivotal New Approach To Groundwater Quality Assessment, M. L. Cherry, T. Gilmore, T. Messer, Y. Li, J. Westrop Jan 2022

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

School of Natural Resources: Faculty Publications

No abstract provided.


Plague Risk In The Western United States Over Seven Decades Of Environmental Change, Colin J. Carlson, Sarah N. Bevins, Boris V. Schmid Jan 2022

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

United States Department of Agriculture Wildlife Services: Staff Publications

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


Wild Pig Removal Reduces Pathogenic Bacteria In Low-Order Streams, Sara A. Bolds, B. Graeme Lockaby, Latif Kalin, Stephen S. Ditchkoff, Mark D. Smith, Kurt Vercauteren Jan 2022

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

United States Department of Agriculture Wildlife Services: Staff Publications

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


A Model For Leveraging Animal Movement To Understand Spatio-Temporal Disease Dynamics, Mark Q. Wilber, Anni Yang, Raoul Boughton, Kezia R. Manlove, Ryan S. Miller, Kim M. Pepin, George Wittemyer Jan 2022

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

United States Department of Agriculture Wildlife Services: Staff Publications

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


Transverse Oscillating Bubble Enhanced Laser‑Driven Betatron X‑Ray Radiation Generation, Rafal Rakowski, Ping Zhang, Kyle Jensen, Brendan Kettle, Tim Kawamoto, Sudeep Banerjee, Colton Fruhling, Grigory Golovin, Daniel Haden, Matthew S. Robinson, Donald Umstadter, Bradley A. Shadwick, Matthias Fuchs Jan 2022

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

Department of Physics and Astronomy: Faculty Publications

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


Spin Hall Effect Of Vorticity, Edward Schwartz, Hamed Vakili, Moaz Ali, Alexey Kovalev Jan 2022

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

Department of Physics and Astronomy: Faculty Publications

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