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Articles 40081 - 40110 of 196067

Full-Text Articles in Engineering

Data Supporting Effects Of Uv-C Disinfection On N95 And Kn95 Filtering Facepiece Respirator Reuse, Castine A. Bernardy, James Malley Jan 2022

Data Supporting Effects Of Uv-C Disinfection On N95 And Kn95 Filtering Facepiece Respirator Reuse, Castine A. Bernardy, James Malley

Data Catalog

UV is a proven decontamination tool for microbial pathogens, including the SARS-CoV-2 virus. Lower log inactivation was observed on FFRs than would have been predicted by aqueous-based UV dose-response data for MS-2 bacteriophage and E. coli. Results have demonstrated that FFR materials yield varying results in terms of effective disinfection in experiments conducted on KN95 and N95 face respirators. The highest inactivation for both surrogates was observed with respirator KN95 B. The respirator yielded 3 and 2.75 log inactivation for E. coli and MS-2, respectively at UV doses of 1500 mJ/cm2. KN95 A yielded the lowest …

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Academy Presidents And Institutional Members, Academy Editors Jan 2022

Academy Presidents And Institutional Members, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Table Of Contents, Academy Editors Jan 2022

Table Of Contents, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Seasonal Testicular Histology And Acystic Lobular Spermatogenesis In The Western Lesser Siren, Siren Intermedia Nettingi (Caudata: Sirenidae), Stanley E. Trauth Jan 2022

Seasonal Testicular Histology And Acystic Lobular Spermatogenesis In The Western Lesser Siren, Siren Intermedia Nettingi (Caudata: Sirenidae), Stanley E. Trauth

Journal of the Arkansas Academy of Science

I investigated the seasonal testicular histology and acystic lobular spermatogenesis in the Western Lesser Siren, Siren intermedia nettingi, from periodic sampling of this salamander over a span of 21 yr (1994-2015) in northeastern Arkansas. My results include the following general findings: 1) the largest testicular lobules occurred primarily in January-February during spermiogenesis and spermatozoa maturation; 2) lobular regression and spermatogenic cell recrudescence were underway by late March; 3) proliferation of secondary spermatogonia in lobules was prominent in May; 4) transformation of secondary spermatogonia into primary spermatocytes occurred by mid-July, and these cells became larger in diameter through increased nuclear …

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Dominant Frequency Component Tracking Of Noisy Time-Varying Signals Using The Linear Predictive Coding Pole Processing Method, Jin Xu, Mark Davis, Ruairí De Fréin Jan 2022

Dominant Frequency Component Tracking Of Noisy Time-Varying Signals Using The Linear Predictive Coding Pole Processing Method, Jin Xu, Mark Davis, Ruairí De Fréin

Articles

The linear predictive coding pole processing (LPCPP) method proposed in our previous work overcomes the shortcomings of the LPC method, especially its sensitivity to noise and the filter order. The LPCPP method is a parameterised method that involves processing the LPC poles to produce a series of reduced-order filter transfer functions to estimate the dominant frequency components of a signal. This paper analyses the ability of the LPCPP method to track the frequency changes of noisy, time-varying signals in real-time. Linear chirped frequency modulation signals are used in a series of experiments to simulate signals with different rates of frequency …

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Formation Of Gold Nanoparticle Self-Assembling Films In Various Polymer Matrices For Sers Substrates, Ksenia A. Maleeva, Ilia E. Kaliya, Anton P. Tkach, Anton A. Babaev, Michail Baranov, Kevin Berwick, Tatiana S. Perova, Alexander V. Baranov, Kirill V. Bogdanov Jan 2022

Formation Of Gold Nanoparticle Self-Assembling Films In Various Polymer Matrices For Sers Substrates, Ksenia A. Maleeva, Ilia E. Kaliya, Anton P. Tkach, Anton A. Babaev, Michail Baranov, Kevin Berwick, Tatiana S. Perova, Alexander V. Baranov, Kirill V. Bogdanov

Articles

Surface-enhanced Raman spectroscopy (SERS) is regarded as a versatile tool for studying the composition and structure of matter. This work has studied the preparation of a SERS substrate based on a self-assembling plasmonic nanoparticle film (SPF) in a polymer matrix. Several synthesis parameters for the SPF are investigated, including the size of the particles making up the film and the concentration and type of the self-assembling agent. The result of testing systems with different characteristics is discussed using a model substance (pseudo isocyaniniodide). These models can be useful in the study of biology and chemistry. Research results contain the optimal …

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Mos2 Based Memristive Synapses For Neuromorphic Computing, Adithi Pandrahal Krishnaprasad Sharada Jan 2022

Mos2 Based Memristive Synapses For Neuromorphic Computing, Adithi Pandrahal Krishnaprasad Sharada

Electronic Theses and Dissertations, 2020-2023

Brain inspired computing enabled by memristors have gained prominence over the years due to its nano-scale footprint, reduced complexity for implementing synapses and neurons. Several demonstrations show two-dimensional (2D) materials as a promising platform for realization of robust and energy-efficient memristive synapses. Ideally, a synapse should exhibit low cycle-to-cycle (C-C) and device-to-device (D-D) variability along with high maximum /minimum conductance (Gmax/Gmin) ratio, linearity and symmetry in weight update for obtaining high learning accuracy in neural networks (NNs). However, the demonstration of neuromorphic circuits using conventional materials systems has been limited by high C-C and D-D variability and non-linearity in the …

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Reconfigurable Load-Modulated Power Amplifier For Energy- And Spectrum-Efficient Wireless Communications, Haifeng Lyu Jan 2022

Reconfigurable Load-Modulated Power Amplifier For Energy- And Spectrum-Efficient Wireless Communications, Haifeng Lyu

Electronic Theses and Dissertations, 2020-2023

With the increasing demand for faster date rates and extensive user connectivities, the complex modulation schemes and large-scaled arrays have been widely researched and employed in the modern wireless links e.g., 5G and beyond-5G systems. These pose major challenges to design the power amplifiers (PAs) to accommodate the system level evolution. As the critical part, the power amplifiers (PAs) dominate the output power, efficiency, linearity and reliability of the radio frequency (RF) transmitter. Consequently, the PA's capability of maintaining an efficient, linear and reliable signal amplification operation is essential to the communication systems. On the other hand, due to the …

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4.74 Ghz Harmonically Operated Saw Device For Sensing Applications And Interrogation System, Michael Morales Otero Jan 2022

4.74 Ghz Harmonically Operated Saw Device For Sensing Applications And Interrogation System, Michael Morales Otero

Electronic Theses and Dissertations, 2020-2023

Surface acoustic wave (SAW) devices have provided solutions to many sensor applications. With the increasing use of the electromagnetic spectrum, the adoption of higher frequencies for new developments is becoming a necessity. SAW devices represent a solution for advancing many emerging sensor's needs given their inherent advantages such as: wireless operation, low cost, and ease of fabrication. However, the SAW technology has been typically limited to frequencies under 3 GHz due to size limitations, increased SAW losses, and the need of an interrogation system suitable for reading SAW sensors at higher frequencies. This dissertation presents the work done to push …

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Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry Jan 2022

Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry

Electronic Theses and Dissertations, 2020-2023

Medical diagnostic devices are in high demand due to increasing cases of neurodegenerative diseases in the aging population and pandemic outbreaks in our increasingly connected global community. Devices capable of detecting the presence of a disease in its early stages can have dramatic impacts on how it can be treated or eliminated. High cost and limited accessibility to diagnostic tools are the main barriers preventing potential patients from receiving a timely disease diagnosis. This dissertation presents several devices that are aimed at providing higher quality medical diagnostics at a low cost. Brain function is commonly studied with systems detecting the …

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Power Inductors: Design, Modeling And Analysis, Subash Pokharel Jan 2022

Power Inductors: Design, Modeling And Analysis, Subash Pokharel

Electronic Theses and Dissertations, 2020-2023

Power inductors, or reactors as they are called in the power industry, are one of the fundamental components of a power system. They serve various purposes in both conventional and emerging power systems including: power flow control, fault current limitation, reactive power compensation, harmonic filtering, and others. This dissertation explores the design and applications of conventional power inductors and ways to overcome their shortcomings and expand their functionalities. In addition, novel inductor designs are proposed and analyzed to address power system challenges. A series of inductors, including traditional constant reactance inductor, gapless ferromagnetic core reactor (GFCR) (both costant and variable …

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Reduced Footprint Probabilistic Inference Networks Using Novel Hybrid She-Mtj/Cmos Based Majority Gate, Harshavardhan Reddy Thummala Jan 2022

Reduced Footprint Probabilistic Inference Networks Using Novel Hybrid She-Mtj/Cmos Based Majority Gate, Harshavardhan Reddy Thummala

Electronic Theses and Dissertations, 2020-2023

In recent years, innovations in machine learning using artificial neural networks (ANN) have significantly increased and led to various applications like image recognition, text classification, machine translation, sequence recognition, etc. Earlier, research was focused on software-based DBNs, which are implemented on conventional von-Neumann architectures that provided flexibility but had few limitations. Recent studies have implemented hardware-based designs like FPGA-based, CMOS based, RRAM-based, and MRAM-based designs to overcome these limitations. Hybrid CMOS-MTJ-based RBMs provided significant area and energy improvements compared to other techniques. We herein implemented Spatial and Temporal redundant probabilistic interpolation network to improve the accuracy and provide fault tolerance …

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Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian Jan 2022

Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian

Electronic Theses and Dissertations, 2020-2023

Smart grids and smart buildings are two highly interdependent energy infrastructure systems. Buildings rely on the grid to provide reliable power while their flexibility can also be utilized to enhance the reliability and efficiency of power system operations. The quantification of heating, ventilation, and air condition (HVAC) system flexibility is critical to the operations of both the grid and buildings in demand response (DR) programs. However, the flexibility quantification is challenging due to the non-linearity and non-convexity of thermal dynamics associated with HVAC components. This dissertation proposes a novel HVAC flexibility quantification method based on a semidefinite programming (SDP) formulation. …

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Interactions Of Aerosol Droplets With Ventilated Airflows In The Context Of Airborne Pathogen Transmission, Steven Schroeder Jan 2022

Interactions Of Aerosol Droplets With Ventilated Airflows In The Context Of Airborne Pathogen Transmission, Steven Schroeder

Electronic Theses and Dissertations, 2020-2023

This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with a crossflow of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how ventilation can alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and …

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Characteristics Of Rotating Detonation Engines For Propulsion And Power Generation, Robert Burke Jan 2022

Characteristics Of Rotating Detonation Engines For Propulsion And Power Generation, Robert Burke

Electronic Theses and Dissertations, 2020-2023

Conventional engines are limited by the efficiency of their combustion mode. Compared to present constant pressure deflagration-based engines, detonation-based systems can realize a higher thermodynamic cycle efficiency, making them an attractive candidate for next generation propulsion systems that will take humanity to hypersonic speeds and even to Mars. For all its performance gains, detonation engines are still far off from implementation. One system, the rotating detonation engine (RDE) is promising as a detonation-based engine concept for its stability, simplicity, and versatility. For these reasons, RDEs have been the subject of studies internationally in efforts to understand their operation and integration …

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An Investigation Of The Relationship Between Respiration And Seismocardiographic Signals Using Signal Processing, Machine Learning And Finite Element Analysis, Tanvir Hassan Jan 2022

An Investigation Of The Relationship Between Respiration And Seismocardiographic Signals Using Signal Processing, Machine Learning And Finite Element Analysis, Tanvir Hassan

Electronic Theses and Dissertations, 2020-2023

Cardiovascular disease (CVD) is one of the major causes of death worldwide. Disease management, as well as patient health, can be significantly improved by early detection of patient deterioration and proper intervention. Review of the patient's medical history and physical examination including stethoscope auscultation and electrocardiograms (ECG), echocardiography imaging, numerous blood testing, and computed tomography are common means of evaluating cardiac function. Seismocardiographic (SCG) signals are the vibrations of the chest wall due to the mechanical activity of the heart. These signals can provide useful information about heart function and could be used to diagnose cardiac problems. The variability in …

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Enhancing The Decision-Making Process For Public-Private Partnerships' Concession Agreements: Socio-Economic Sustainability Approaches, Faisal Alghamdi Jan 2022

Enhancing The Decision-Making Process For Public-Private Partnerships' Concession Agreements: Socio-Economic Sustainability Approaches, Faisal Alghamdi

Electronic Theses and Dissertations, 2020-2023

Designing a concession for Public-Private Partnerships (PPP) agreements is a complicated process due to the number of variables that need to be considered. The PPP concession has many parameters and components, and a change in one component will considerably impact other components. Hence, the determination of the fair values of the concession components needs to be based on mutual benefits between the concession participants. The concession participants have different parts in the development of the concession; hence, they have different perspectives and goals. Therefore, the concession design needs to be constructed to balance the interests of the involved parties to …

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The Effects Of Supersonic Reacting Flow Over A Wedge, Taylor R. Brown Jan 2022

The Effects Of Supersonic Reacting Flow Over A Wedge, Taylor R. Brown

Honors Undergraduate Theses

There is a growing need for a fundamental understanding of how detonations are formed and sustained as propulsion technology advances toward the use of detonation-based engines. The deflagration-to-detonation transition (DDT) phenomenon is studied to better understand both the fundamentals of detonation physics and the conditions surrounding how detonations are formed and sustained. This research aims to study the effects of a wedge on DDT and detonation formation. A hydrogen-air mixture is pumped into a chamber and ignited by a spark plug. Turbulence-driven flame acceleration is induced by turbulators in the chamber through which the flame propagates. The flame then flows …

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Exploration Of Warm-Up Protocols On Muscular Fatigue, Sahil Kapadia Jan 2022

Exploration Of Warm-Up Protocols On Muscular Fatigue, Sahil Kapadia

Honors Undergraduate Theses

Muscular dystrophy is a genetically linked myopathy with no cure available. The lack of a cure makes early detection and treatment of muscular dystrophy imperative. When reviewing protocols examining muscular fatigue at submaximal isometric contractions, proper warm-up appeared to be absent and could have caused skewed results and conclusions. This study examines the effects of implementing a warm-up protocol before fatiguing trials. In this study, 10 adult subjects conducted fatiguing protocols with the right rectus at submaximal isometric contractions. The warm-up period included a light walk along with contractions at 20% and 33% of maximal voluntary isometric contraction (MVIC) levels. …

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Probing The Effect Of Hyperglycemia On Endothelial Force Generation And Transmission, Jovani J. Gutierrez Jan 2022

Probing The Effect Of Hyperglycemia On Endothelial Force Generation And Transmission, Jovani J. Gutierrez

Honors Undergraduate Theses

This thesis intends to utilize biomechanics to study the endothelial biomechanical response in a static hyperglycemic microenvironment. Hyperglycemia is a diabetic condition with abnormally high levels of glucose in the bloodstream. The effects of hyperglycemia over time lead to vascular complications resulting in patients being more prone to cardiovascular diseases. Current studies have focused on the molecular mechanisms affected by hyperglycemia; however, the mechanical mechanisms by which hyperglycemia causes vascular structural and functional changes are understudied. Therefore, to study the effects of hyperglycemia in the endothelium, Human Umbilical Vein Endothelial Cells (HUVEC) were cultured under three glucose conditions: normal glucose …

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Influence Of Growth Parameters On The Synthesis Of Mos2 Films, Victor Okonkwo Jan 2022

Influence Of Growth Parameters On The Synthesis Of Mos2 Films, Victor Okonkwo

Honors Undergraduate Theses

Information processing is crucial in modern society, placing a great emphasis on the performance of optoelectronic devices to match ever increasing processing and memory needs. Within these devices, MoS2 has demonstrated great potential as transistors due to its enhanced electrostatic control. As increased layer thickness of quality MoS2 films have been shown to boost the performance of its transistors, growth parameters for the synthesis of ideally uniform and large area multilayered films via chemical vapor deposition were investigated. By increasing the flow pressure in the system and the growth time, increasing levels of thickness and nucleation density was …

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Examining Cooperative System Responses Against Grid Integrity Attacks, Alexander D. Parady Jan 2022

Examining Cooperative System Responses Against Grid Integrity Attacks, Alexander D. Parady

Honors Undergraduate Theses

Smart grid technologies are integral to society’s transition to sustainable energy sources, but they do not come without a cost. As the energy sector shifts away from a century’s reliance on fossil fuels and centralized generation, technology that actively monitors and controls every aspect of the power infrastructure has been widely adopted, resulting in a plethora of new vulnerabilities that have already wreaked havoc on critical infrastructure. Integrity attacks that feedback false data through industrial control systems, which result in possible catastrophic overcorrections and ensuing failures, have plagued grid infrastructure over the past several years. This threat is now at …

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Thrust Augmentation Of Rotating Detonation Rocket Engines, Alexander G. Rodriguez Jan 2022

Thrust Augmentation Of Rotating Detonation Rocket Engines, Alexander G. Rodriguez

Honors Undergraduate Theses

This thesis aims to perform a detailed analysis on a 5th Order Polynomial Nozzle, verifying its effectiveness in improving the thrust performance of a Rotating Detonation Rocket Engine. Rotating detonation engines are a promising engine type that uses detonations as a means of combustion rather than traditional conflagration. Through this method, these engines can produce significant amounts of energy while burning less fuel in the process. However, exhaust flow instabilities and swirl limit the engine's potential for use as a means of propulsion. The 5th Order Polynomial Nozzle was previously demonstrated to reduce and control this swirl; however, analysis was …

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Learning And Decision Making In Social Media Networks, Zhecheng Qiang Jan 2022

Learning And Decision Making In Social Media Networks, Zhecheng Qiang

Electronic Theses and Dissertations, 2020-2023

Social media is a virtual community where users share news, ideas, interests, and information. Learning the information diffusion dynamics and making decisions correspondingly, e.g., selecting the seed nodes to maximize the influence, have been widely applied to the areas of viral marketing and cyber security. In this dissertation, we study the problem of learning diffusion process, i.e., infection prediction, in social media networks utilizing both feature-based machine learning methods and mathematical model-based methods. For feature-based machine learning methods, the neighborhood information is treated as an important feature together with user profile and content similarity features. For model-based methods, two distinctive …

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Engineering The Electrode Properties For Developing High Performance Supercapacitors, Kowsik Sambath Kumar Jan 2022

Engineering The Electrode Properties For Developing High Performance Supercapacitors, Kowsik Sambath Kumar

Electronic Theses and Dissertations, 2020-2023

Rising global warming concern demands the need for a rapid transition to renewable energy sources. The intermittent nature of these sources emphasizes the requirement of developing highly efficient electrochemical energy storage devices like supercapacitors and batteries. Supercapacitors are at the forefront of powering various devices spanning from electric cars to aircraft. Here, we have engineered the electrode material properties for developing supercapacitors with high capacitance, energy density and cycle life. Among the electrode materials, we have focused on improving the energy storage performance of 2D materials like graphene oxide (GO) and tungsten disulfide (WS2), in addition to metal oxides such …

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An Investigative Design Of Gas Jet Nozzles And Their Flow Field Effect On Spatial Distribution, Adam Phengsomphone Jan 2022

An Investigative Design Of Gas Jet Nozzles And Their Flow Field Effect On Spatial Distribution, Adam Phengsomphone

Honors Undergraduate Theses

Within this study, the presented material has the objective of providing insight and design characteristics for gas jet nozzles that experimentalists and researchers should consider when utilizing this experimental method. Firstly, this study introduces the developing history and necessity for gas jet experiments and its well-known drawbacks, eventually leading to recent studies and founded knowledge regarding the nozzle geometry dependence on the flow field. The simulation methodology of this study will be presented where the discretization of the computational domain, selection of the flow physics model, and overall design of the nozzle geometry is explained and justified. The flow field …

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An Introduction To The Comparison Of Seismocardiography And Phonocardiography, Anna C. Voyatzoglou Jan 2022

An Introduction To The Comparison Of Seismocardiography And Phonocardiography, Anna C. Voyatzoglou

Honors Undergraduate Theses

The intent of this thesis is to lay groundwork for examining the relationship between seismocardiography (SCG) and phonocardiography (PCG). Both are methods of measuring and describing heart mechanical function. SCG is described as chest vibrations while the heart beats, and PCG is described as acoustic chest surface signal believed to represent the heart valves opening or closing. SCG and PCG have both been used separately in clinical and research settings, but there is currently no clear comparison between the two. Therefore, there has been no way at the present to understand how one signal might inform the other. This study …

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Design And Development Of Medical Devices For Multifaceted Applications, Madisyn Messmore Jan 2022

Design And Development Of Medical Devices For Multifaceted Applications, Madisyn Messmore

Honors Undergraduate Theses

The fields of biotechnology and biomedical sciences are rapidly evolving and involve the constant growth of knowledge. As a consequence, engineering design has to also remain at the cutting edge in order to not inhibit the growth of these fields. This study focuses on engineering design and analysis as it pertains to the field of biotechnology, at every step of the engineering process. More specifically, how the engineering design and analysis approach can assist in solving medical problems relating to bone diseases and biomaterials. The first part of the study focuses on a project to design and manufacture a novel …

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Decoding Task-Based Fmri Data Using Graph Neural Networks, Considering Individual Differences, Maham Saeidi Jan 2022

Decoding Task-Based Fmri Data Using Graph Neural Networks, Considering Individual Differences, Maham Saeidi

Electronic Theses and Dissertations, 2020-2023

Functional magnetic resonance imaging (fMRI) is a non-invasive technology that provides high spatial resolution in determining the human brain's responses and measures regional brain activity through metabolic changes in blood oxygen consumption associated with neural activity. Task fMRI provides an opportunity to analyze the working mechanisms of the human brain during specific task performance. Over the past several years, a variety of computational methods have been proposed to decode task fMRI data that can identify brain regions associated with different task stimulations. Despite the advances made by these methods, several limitations exist due to graph representations and graph embeddings transferred …

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Self-Powered Microgravity Resistance Exercise With Soft Pneumatic Exoskeletons, Aislinn Marcee, Emma Treadway Jan 2022

Self-Powered Microgravity Resistance Exercise With Soft Pneumatic Exoskeletons, Aislinn Marcee, Emma Treadway

Engineering Faculty Research

As preparations continue towards sending humans on a 3-year mission to Mars, space programs must find solutions to combat muscular atrophy experienced by astronauts during extended time in microgravity. One method currently used to combat muscle deterioration is daily resistance training sessions using an apparatus like the ARED or CEVIS exercise devices, but these daily exercise sessions are not expected to be enough to protect the muscles during longer missions. To help combat muscular atrophy, we propose self-resistance outside of the daily exercise sessions implemented through soft pneumatic exoskeletons that could be integrated into astronauts’ suits, augmenting the formal exercise …

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