Physical Sciences and Mathematics Commons^™

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

Promoting Diversity In Academic Research Communities Through Multivariate Expert Recommendation, Omar Salman

Graduate Theses and Dissertations

Expert recommendation is the process of identifying individuals who have the appropriate knowledge and skills to achieve a specific task. It has been widely used in the educational environment mainly in the hiring process, paper-reviewer assignment, and assembling conference program committees. In this research, we highlight the problem of diversity and fair representation of underrepresented groups in expertise recommendation, factors that current expertise recommendation systems rarely consider. We introduce a novel way to model experts in academia by considering demographic attributes in addition to skills. We use the h-index score to quantify skills for a researcher and we identify five …

Investigation Of Factors Influencing Recombination Versus Disproportionation Of Complex Radicals Formed By C-N Homolysis Of Breslow Type Intermediates And Related Compounds, Taylor Burnett

Graduate Theses and Dissertations

Electron rich enamines are capable of C-N bond homolysis and subsequent recombination and/or disproportionation. It is unclear what causes these radicals to undergo recombination or disproportionation. Density Functional Theory (DFT) calculations do not provide a transition state for the recombination and disproportionation processes and therefore they cannot be used to predict the favorable reaction. Breslow intermediates formed by deprotonation of thiazolium salts and reaction with aromatic aldehydes are examples of electron rich enamines. These breslow intermediates can undergo C-N bond homolysis to form a radical pair the either recombine or disproportionate. Upon investigation of the factors influencing recombination and disproportionation, …

Privacy-Preserving Cloud-Assisted Data Analytics, Wei Bao

Graduate Theses and Dissertations

Nowadays industries are collecting a massive and exponentially growing amount of data that can be utilized to extract useful insights for improving various aspects of our life. Data analytics (e.g., via the use of machine learning) has been extensively applied to make important decisions in various real world applications. However, it is challenging for resource-limited clients to analyze their data in an efficient way when its scale is large. Additionally, the data resources are increasingly distributed among different owners. Nonetheless, users' data may contain private information that needs to be protected.

Cloud computing has become more and more popular in …

Knowledge Discovery From Complex Event Time Data With Covariates, Samira Karimi

Graduate Theses and Dissertations

In particular engineering applications, such as reliability engineering, complex types of data are encountered which require novel methods of statistical analysis. Handling covariates properly while managing the missing values is a challenging task. These type of issues happen frequently in reliability data analysis. Specifically, accelerated life testing (ALT) data are usually conducted by exposing test units of a product to severer-than-normal conditions to expedite the failure process. The resulting lifetime and/or censoring data are often modeled by a probability distribution along with a life-stress relationship. However, if the probability distribution and life-stress relationship selected cannot adequately describe the underlying failure …

Assessing Impacts Of Winter-Hay Feeding On Soil And Forage Nutrient Dynamics In A Rotationally-Grazed Pasture System In Arkansas, Lawrence Gordon Berry Iv

Graduate Theses and Dissertations

More than 38 % of United States’ rural land area was used for grazing (i.e., pastureland or rangeland) ruminant animals in 2017, constituting the largest private land use group. The expansive nature of these lands means that grazing and pasture management decisions have potential to impact water quality as well as profit margins. As a result, beef producers are under increased pressure from economic and environmental standpoints to limit application of nutrients beyond those required to grow the forage needed for animal consumption. At the same time, a large amount of nutrients is recycled back to pasture systems directly from …

Structural And Electronic Properties Of Few-Layer Monochalcogenides, Brandon Joel Miller

Graduate Theses and Dissertations

This work discusses a new class of materials with novel properties that have only recently begun being studied. These materials are two-dimensional group IV-VI monochalcogenides, so named because they are formed from group IV (carbon group) and group VI (chalcogens) elements. These materials display several interesting physical properties such as ferroelasticity and ferroelectricity, and the contents within Chapters Two, Three, and Four concern a collaborative effort between theory and experiment between our group at the University of Arkansas and Dr. Kai Chang at the Max Planck Institute of Microstructure Physics in Halle, Germany in studying these properties. This thesis is …

Paying Attention To Video Object Pattern Understanding, Wenguan Wang, Jianbing Shen, Xiankai Lu, Steven C. H. Hoi, Haibin Ling

Research Collection School Of Computing and Information Systems

This paper conducts a systematic study on the role of visual attention in video object pattern understanding. By elaborately annotating three popular video segmentation datasets (DAVIS) with dynamic eye-tracking data in the unsupervised video object segmentation (UVOS) setting. For the first time, we quantitatively verified the high consistency of visual attention behavior among human observers, and found strong correlation between human attention and explicit primary object judgments during dynamic, task-driven viewing. Such novel observations provide an in-depth insight of the underlying rationale behind video object pattens. Inspired by these findings, we decouple UVOS into two sub-tasks: UVOS-driven Dynamic Visual Attention …

Performance Optimization With An Integrated View Of Compiler And Application Knowledge, Ruiqin Tian

Dissertations, Theses, and Masters Projects

Compiler optimization is a long-standing research field that enhances program performance with a set of rigorous code analyses and transformations. Traditional compiler optimization focuses on general programs or program structures without considering too much high-level application operations or data structure knowledge. In this thesis, we claim that an integrated view of the application and compiler is helpful to further improve program performance. Particularly, we study integrated optimization opportunities for three kinds of applications: irregular tree-based query processing systems such as B+ tree, security enhancement such as buffer overflow protection, and tensor/matrix-based linear algebra computation. The performance of B+ tree query …

Ultrafast Optical Control And Characterization Of Carrier And Spin Dynamics In Novel Magnetic Topological Insulator Systems, Peiwen Liu

Dissertations, Theses, and Masters Projects

Magnetic topological insulators (MTIs) are of considerable interest in developing novel spintronics and quantum computing applications. Under the topological protection by time-reversal Z2 invariant number, magnetic topological insulators are provided with robust electronic and magnetic properties against local perturbations. The quantum anomalous Hall effect (QAHE), which harbors dissipationless chiral edge states in MTIs, provides a competitive platform for future low-power consumption and high-speed spintronic devices. Although the present studies on both bulk and surface magnetic properties in MTIs have made significant progress, the in-depth understanding of the exchange couplings and the interaction between the two magnetization sources is far from …

Low-Overhead Techniques For Secure And Reliable Gpu Computing, Gurunath Kadam

Dissertations, Theses, and Masters Projects

In recent years, Graphics Processing Units (GPUs) have become a de facto choice to accelerate the computations in various domains such as machine learning, security, financial and scientific computing. GPUs leverage the inherent data parallelism in the target applications to provide high throughput at superior energy efficiency. Due to the rising usage of GPUs for a large number of applications, they are facing new challenges, especially in the security and reliability domains. From the security side, recently several microarchitectural attacks targeting GPUs have been demonstrated. These attacks leak the secret information stored on GPUs, for example, the parameters of a …

Estuarine Microbiomes And Biogeochemistry: Impacts Of Spatiotemporal Variation, Algal Blooms, And Microplastics, Samantha Grace Fortin

Dissertations, Theses, and Masters Projects

Estuaries are biogeochemical hotspots connecting terrestrial and coastal ecosystems. Anthropogenic disturbances, including increased nitrogen loading and plastic pollution, may have significant impacts on estuarine carbon and nitrogen cycling by altering microbiome structure and functions. The overarching goal of this dissertation was to examine how microbiomes and their associated biogeochemical processes are influenced by natural variation and anthropogenic disturbances in the York River Estuary (YRE). In chapter 2, spatial and temporal variation in benthic microbiomes and the rates of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were examined to determine biotic and abiotic drivers of nitrogen …

Differential Nitrogen Uptake By Aquatic Communities In A Chesapeake Bay Tributary And In The Coastal Alaskan Arctic, Brianna Stanley

Dissertations, Theses, and Masters Projects

Nitrogen (N) is one of the essential building blocks for all life and is available in the form of dissolved N in aquatic ecosystems. It is important to understand how this N can support primary and secondary production mediated by phytoplankton and bacteria, respectively, as it can affect both microbial loop biogeochemistry and the higher trophic levels of food webs. Nitrogen studies have traditionally focused on dissolved inorganic N (DIN) as a labile N source. Dissolved organic N (DON), while still often considered refractory, has been increasingly recognized as an important N source supporting primary and secondary production. However, the …

Sediment Transport And Trapping On The Ayeyarwady-Martaban Continental Shelf, Matthew Joshua Fair

Dissertations, Theses, and Masters Projects

The Ayeyarwady and Thanlwin Rivers, which primarily drain Myanmar, are together one of the largest point sources of freshwater and sediment to the global ocean. Much of the estimated 600 Mt of river sediment annually carried by the combined Ayeyarwady and Thanlwin River system is delivered to a wide continental shelf in the northern Andaman Sea. Called here the Ayeyarwady-Martaban continental shelf, this area is influenced by strong tides, monsoon conditions, and periodic cyclones; however, the processes that dominate dispersal of fluvial material in the coastal ocean of this system remain poorly understood. The shelf exhibits a dramatic asymmetry of …

Mobile Application To Travel The World Using Virtual Reality And Machine Learning, Valentina Quiroga, Francisco Olivares, José Najera

ICT

This research intends to make travel and culture an accessible possibility for all. With a phone and a VRHeadset, people will have the opportunity to see some of the most amazing scenes in the world and learn about the history and culture of famous landmarks without leaving the comfort of their own homes.

The Shape Of A Photon, Christopher C. O’Neill

ICT

The purpose of this research is to use quantum operators, known as ‘Dimensional Gate Operator’ (DGO) as a means of investigating the properties of quantum wave functions; in this case the shape of the wave function of light.

Observation Of Gravitational Waves From Two Neutron Star–Black Hole Coalescences, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We report the observation of gravitational waves from two compact binary coalescences in LIGO's and Virgo's third observing run with properties consistent with neutron star–black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo and the second by all three LIGO–Virgo detectors. The source of GW200105 has component masses and , whereas the source of GW200115 has component masses and (all measurements quoted at the 90% credible level). The probability that the secondary's mass is below the maximal mass of a neutron star is …

Comparing Dietary Score Associations With Lipoprotein Particle Subclass Profiles: A Cross-Sectional Analysis Of A Middle-To Older-Aged Population, Seán R. Millar, Pilar Navarro, Janas M. Harrington, Nitin Shivappa Mbbs, Mph, Ph.D., James Hébert Scd, Ivan J. Perry, Catherine M. Phillips

Faculty Publications

Background and objectives: Lipoprotein particle concentrations and size are associated with increased risk for atherosclerosis and premature cardiovascular disease. Studies also suggest that certain dietary behaviours may be cardioprotective. Limited comparative data regarding any dietary score/index-lipoprotein particle subclass associations exist. Thus, our objective was to assess relationships between the Dietary Approaches to Stop Hypertension (DASH), Health Eating Index-2015 (HEI-2015), Mediterranean Diet (MD) and Energy-adjusted Dietary Inflammatory Index (E-DII™) scores and plasma lipids and lipoprotein profiles to test the hypothesis that healthier diet (better quality and more anti-inflammatory) would be associated with a more favourable lipoprotein profile.

Materials and methods: This …

Evaluation Of Circulating Levels Of Interleukin-10 And Interleukin-16 And Dietary Inflammatory Index In Lebanese Knee Osteoarthritis Patients, Zeina El-Ali, Germine El-Kassas, Fouad M. Ziade, Nitin Shivappa Mbbs, Mph, Ph.D., James Hébert Scd, Nisrine Bissar

Faculty Publications

Objectives

To investigate plasma concentrations of Interleukin-16 (IL-16) and Interleukin-10 (IL-10) in Lebanese knee osteoarthritis (KOA) patients and to examine the association between the diet-associated inflammation and increased risk for KOA.

Methods

A total of 208 study participants were assigned to one of the 3 groups: Diagnosed Knee Osteoarthritis group (DKOA) (N = 78); Undiagnosed Knee Osteoarthritis group (UKOA) (N = 60) and controls matched on age, sex and sociodemographic characteristics (N = 70). UKOA represents KOA features before they are altered by therapeutic intervention and lifestyle modifications that follow the diagnosis. Energy-adjusted dietary inflammatory index (E-DII™) scores were calculated …

Measurements Of Partial Branching Fractions Of Inclusive B →Xuℓ+Νℓ Decays With Hadronic Tagging, L. Cao, W. Sutcliffe, R. Van Tonder, F. U. Bernlochner, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu, M. Bauer, P. Behera, K. Belous, J. Bennett, M. Bessner, V. Bhardwaj, T. Bilka

Faculty and Student Publications

We present measurements of partial branching fractions of inclusive semileptonic B→Xuℓ+νℓ decays using the full Belle dataset of 711 fb-1 of integrated luminosity at the ϒ(4S) resonance and for ℓ=e, μ. Inclusive semileptonic B→Xuℓ+νℓ decays are Cabibbo-Kobayashi-Maskawa (CKM) suppressed and measurements are complicated by the large background from CKM favored B→Xcℓ+νℓ transitions, which have a similar signature. Using machine learning techniques, we reduce this and other backgrounds effectively, while retaining access to a large fraction of the B→Xuℓ+νℓ phase space and high signal efficiency. We measure partial branching fractions in three phase-space regions covering about 31% to 86% of the …

Comparing Instruments For Measuring Runoff From Experimental Ecoroof Platforms: A Case Study On Test Plots At Portland State University, Chance F. Hodges

University Honors Theses

Stormwater management is a primary ecological benefit ecoroofs provide to ecosystems. Quantification of runoff from large scale ecoroofs is difficult to replicate, so researchers often utilize smaller experimental ecoroof platforms. This approach is becoming increasingly common, so it is useful to compare and contrast approaches for runoff measurement at the platform scale. This paper uses the four 17.86 m² ecoroof platforms located on the Science Research and Teaching Center (SRTC) at Portland State University (PSU) in Portland, OR as a case study. A unique condition of these platforms is that they are installed at grade on the roof with …

Hierarchical Mapping For Crosslingual Word Embedding Alignment, Ion Madrazo Azpiazu, Maria Soledad Pera

Computer Science Faculty Publications and Presentations

The alignment of word embedding spaces in different languages into a common crosslingual space has recently been in vogue. Strategies that do so compute pairwise alignments and then map multiple languages to a single pivot language (most often English). These strategies, however, are biased towards the choice of the pivot language, given that language proximity and the linguistic characteristics of the target language can strongly impact the resultant crosslingual space in detriment of topologically distant languages. We present a strategy that eliminates the need for a pivot language by learning the mappings across languages in a hierarchicalway. Experiments demonstrate that …

Exploring Author Gender In Book Rating And Recommendation, Michael D. Ekstrand, Daniel Kluver

Computer Science Faculty Publications and Presentations

Collaborative filtering algorithms find useful patterns in rating and consumption data and exploit these patterns to guide users to good items. Many of these patterns reflect important real-world phenomena driving interactions between the various users and items; other patterns may be irrelevant or reflect undesired discrimination, such as discrimination in publishing or purchasing against authors who are women or ethnic minorities. In this work, we examine the response of collaborative filtering recommender algorithms to the distribution of their input data with respect to one dimension of social concern, namely content creator gender. Using publicly available book ratings data, we measure …

A Coprocessor-Based Introspection Framework Via Intel Management Engine, Lei Zhou, Fengwei Zhang, Jidong Xiao, Kevin Leach, Westley Weimer, Xuhua Ding, Guojun Wang

Computer Science Faculty Publications and Presentations

During the past decade, virtualization-based (e.g., virtual machine introspection) and hardware-assisted approaches (e.g., x86 SMM and ARM TrustZone) have been used to defend against low-level malware such as rootkits. However, these approaches either require a large Trusted Computing Base (TCB) or they must share CPU time with the operating system, disrupting normal execution. In this article, we propose an introspection framework called Nighthawk that transparently checks system integrity and monitor the runtime state of target system. Nighthawk leverages the Intel Management Engine (IME), a co-processor that runs in isolation from the main CPU. By using the IME, our approach has …

Stability Of Peakons And Periodic Peakons For A Nonlinear Quartic Camassa-Holm Equation, Aiyong Chen, Tongjie Deng, Zhijun Qiao

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, we study the orbital stability of peakons and periodic peakons for a nonlinear quartic Camassa-Holm equation (QCHE).We first verify that the QCHE has global peakon and periodic peakon solutions. Then by the invariants of the equation and controlling the extrema of the solution, we prove that the shapes of the peakons and periodic peakons are stable under small perturbations in the energy space.

Oesense: Employing Occlusion Effect For In-Ear Human Sensing, Dong Ma, Andrea Ferlini, Cecilia Mascolo

Research Collection School Of Computing and Information Systems

Smart earbuds are recognized as a new wearable platform for personal-scale human motion sensing. However, due to the interference from head movement or background noise, commonly-used modalities (e.g. accelerometer and microphone) fail to reliably detect both intense and light motions. To obviate this, we propose OESense, an acoustic-based in-ear system for general human motion sensing. The core idea behind OESense is the joint use of the occlusion effect (i.e., the enhancement of low-frequency components of bone-conducted sounds in an occluded ear canal) and inward-facing microphone, which naturally boosts the sensing signal and suppresses external interference. We prototype OESense as an …

How Important Is The Train-Validation Split In Meta-Learning?, Yu Bai, Minshuo Chen, Pan Zhou, Tuo Zhao, D. Jason Lee, Sham Kakade, Huan Wang, Caiming Xiong

Research Collection School Of Computing and Information Systems

Meta-learning aims to perform fast adaptation on a new task through learning a “prior” from multiple existing tasks. A common practice in meta-learning is to perform a train-validation split (train-val method) where the prior adapts to the task on one split of the data, and the resulting predictor is evaluated on another split. Despite its prevalence, the importance of the train-validation split is not well understood either in theory or in practice, particularly in comparison to the more direct train-train method, which uses all the pertask data for both training and evaluation. We provide a detailed theoretical study on whether …

Page: A Simple And Optimal Probabilistic Gradient Estimator For Nonconvex Optimization, Zhize Li, Hongyan Bao, Xiangliang Zhang, Peter Richtarik

Research Collection School Of Computing and Information Systems

In this paper, we propose a novel stochastic gradient estimator---ProbAbilistic Gradient Estimator (PAGE)---for nonconvex optimization. PAGE is easy to implement as it is designed via a small adjustment to vanilla SGD: in each iteration, PAGE uses the vanilla minibatch SGD update with probability $p_t$ or reuses the previous gradient with a small adjustment, at a much lower computational cost, with probability $1-p_t$. We give a simple formula for the optimal choice of $p_t$. Moreover, we prove the first tight lower bound $\Omega(n+\frac{\sqrt{n}}{\epsilon^2})$ for nonconvex finite-sum problems, which also leads to a tight lower bound $\Omega(b+\frac{\sqrt{b}}{\epsilon^2})$ for nonconvex online problems, where …

Exploring Cross-Modality Utilization In Recommender Systems, Quoc Tuan Truong, Aghiles Salah, Thanh-Binh Tran, Jingyao Guo, Hady W. Lauw

Research Collection School Of Computing and Information Systems

Multimodal recommender systems alleviate the sparsity of historical user-item interactions. They are commonly catalogued based on the type of auxiliary data (modality) they leverage, such as preference data plus user-network (social), user/item texts (textual), or item images (visual) respectively. One consequence of this categorization is the tendency for virtual walls to arise between modalities. For instance, a study involving images would compare to only baselines ostensibly designed for images. However, a closer look at existing models' statistical assumptions about any one modality would reveal that many could work just as well with other modalities. Therefore, we pursue a systematic investigation …

The Multi-Vehicle Cycle Inventory Routing Problem: Formulation And A Metaheuristic Approach, Vincent F. Yu, Audrey Tedja Widjaja, Aldy Gunawan, Pieter Vansteenwegen

Research Collection School Of Computing and Information Systems

This paper presents a new variant of the Multi-Vehicle Cyclic Inventory Routing Problem (MV-CIRP) which aims to determine a subset of customers to be visited, the appropriate number of vehicles used, and the corresponding cycle time and route sequence, such that the total cost (e.g. transportation, inventory, and rewards) is minimized. The MV-CIRP is formulated as a mixed-integer nonlinear programming model. We propose a Simulated Annealing (SA) based algorithm to solve the problem. SA is first tested on the available benchmark Single-Vehicle CIRP (SV-CIRP) instances and compared to the state-of-the-art algorithms. SA is then tested on the benchmark MV-CIRP instances …