Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Electronic Theses and Dissertations

Discipline
Institution
Keyword
Publication Year
File Type

Articles 1141 - 1170 of 4195

Full-Text Articles in Physical Sciences and Mathematics

A Multi-Proxy Paleoecological Reconstruction Of Holocene Climate, Vegetation, Fire And Human Activity In Jamaica, West Indies, Mario A. Williams May 2019

A Multi-Proxy Paleoecological Reconstruction Of Holocene Climate, Vegetation, Fire And Human Activity In Jamaica, West Indies, Mario A. Williams

Electronic Theses and Dissertations

Jamaica is located in the Caribbean biodiversity hotspot and has a rich flora and fauna, most notably characterized by exceptional levels of plant endemism. These natural resources are imperiled by climate change and increasing anthropogenic pressures, therefore highlighting the importance of implementing effective conservation programs to mitigate ecosystem degradation. Paleoecological studies that investigate the diversity and distributions of organisms and their habitats over millennial timescales provide critical long-term spatial and temporal context for the assessment of contemporary environmental problems. Lake sediments are a highly useful archive for the study of prehistoric climate and ecological changes, as biological, chemical and geophysical …

Go to article

Perspectives On Water Resources Risk, Policy, And Stewardship, Anne Marie Lausier May 2019

Perspectives On Water Resources Risk, Policy, And Stewardship, Anne Marie Lausier

Electronic Theses and Dissertations

Water management approaches have historically optimized water for human use and placed lower emphasis on the relationship between ecosystems and humans. Despite efforts to balance human and ecosystem needs, existing management approaches tend to prioritize some needs, knowledges, and values over others. Natural and anthropogenic changes pose challenges to water governance institutions due to policy inflexibility, and may lead to ecosystem degradation, water stress, and conflict among water users. This work seeks to redress these shortcomings through three scholarly contributions. First, a conceptual framework for Water Resources Stewardship is developed in support of equitable and adaptive solutions under changing conditions. …

Go to article

Using Question Variations To Access Alternate Student Thinking About The Same Physical Situations, Jeffrey Mathis Hawkins May 2019

Using Question Variations To Access Alternate Student Thinking About The Same Physical Situations, Jeffrey Mathis Hawkins

Electronic Theses and Dissertations

Assessing students’ understanding of physics is a critical element for improving physics education. This dissertation presents and demonstrates a method to better assess student understanding of physics by varying the types of questions asked of students. The method presented herein, which is based on the Specific Difficulties and Resources frameworks, involves modifying the task students are asked to complete when analyzing the physics of a particular physical situation. Creating question variations that ask students to address a particular correct or incorrect outcome of the physical situation, eliminate an incorrect outcome, or justify a correct outcome provided to them can provide …

Go to article

Optimizing Legume-Based Nitrogen Fertility For Organic Small Grain Systems, Margaret A. Pickoff May 2019

Optimizing Legume-Based Nitrogen Fertility For Organic Small Grain Systems, Margaret A. Pickoff

Electronic Theses and Dissertations

In the past decade, Maine has witnessed a steady rise in consumer demand for organic small grain products, accompanied by the swift creation of new businesses that cater to this demand, including bakeries, flour mills, malt houses, and distilleries. Maine’s farmers have been slower to respond; only a small percentage of the 40,000+ acres of oats and barley being grown in the state, for example, is certified organic (National Agricultural Statistics Service, 2012). Given this combination of land resources, infrastructure, and consumer demand, Maine has the potential to become a regional leader in organic small grain production. According to our …

Go to article

Microplastics In The Digestive System Of The Atlantic Sharpnose Shark (Rhizoprionodon Terraenovae) In Winyah Bay, Sc, Elise Virginia Pullen May 2019

Microplastics In The Digestive System Of The Atlantic Sharpnose Shark (Rhizoprionodon Terraenovae) In Winyah Bay, Sc, Elise Virginia Pullen

Electronic Theses and Dissertations

The digestive tracts and livers of adult male Atlantic sharpnose sharks (N=16), Rhizoprionodon terraenovae, from Winyah Bay, South Carolina were examined for ingested microplastics. R. terraenovae is a small, locally abundant, coastal mesopredatory elasmobranch belonging to the family Carcharhinidae. Microfibers comprised the largest categories of plastics (94% of the total), and were found in 100% of sharks examined. The number of micro- and other plastics ranged from 34 to 75 per individual and totaled 927. The majority of plastics (40%) were blue in coloration, and 55% were <1 mm in length. Microplastics were observed on both the interior and exterior of the organs examined, and three microfibers were embedded within the stomach lining, an observation not previously reported in marine vertebrates and one which represents a potential pathway for the translocation of ingested microplastics.

Go to article

Synergistic Visualization And Quantitative Analysis Of Volumetric Medical Images, Neslisah Torosdagli May 2019

Synergistic Visualization And Quantitative Analysis Of Volumetric Medical Images, Neslisah Torosdagli

Electronic Theses and Dissertations

The medical diagnosis process starts with an interview with the patient, and continues with the physical exam. In practice, the medical professional may require additional screenings to precisely diagnose. Medical imaging is one of the most frequently used non-invasive screening methods to acquire insight of human body. Medical imaging is not only essential for accurate diagnosis, but also it can enable early prevention. Medical data visualization refers to projecting the medical data into a human understandable format at mediums such as 2D or head-mounted displays without causing any interpretation which may lead to clinical intervention. In contrast to the medical …

Go to article

Light Matter Interaction In Single Molecule Magnets, Rebecca Cebulka May 2019

Light Matter Interaction In Single Molecule Magnets, Rebecca Cebulka

Electronic Theses and Dissertations

This dissertation includes a series of experimental realizations which focus on studying the coupling between photons and single-molecule magnets (SMMs) in both the weak and strong coupling regimes. In the weak coupling regime, the aim is to achieve coherent control over the time evolution of the spin of SMMs while applying rapid microwave pulses at sub-Kelvin temperatures, where polarization of the spin bath may be achieved without large magnetic fields, allowing the suppression of dipolar dephasing. The continuing results of this experiment will be to provide a window into fundamental sources of decoherence in single-crystal SMMs in an energy range …

Go to article

Detection Of Mercury Through Surface Plasmon Resonance Of Immobilized Gold Nanorods, Khang Trieu May 2019

Detection Of Mercury Through Surface Plasmon Resonance Of Immobilized Gold Nanorods, Khang Trieu

Electronic Theses and Dissertations

Mercury is a known environmental pollutant that can damage the brain, heart, kidney and lungs upon exposure. Emissions from fossil fuel plants can release mercury into the air, where it can settle into the water supply and be exposed to human and aquatic life. The use of gold nanorods functionalized on solid substrates as a mercury sensor in tap water samples is investigated herein. The functionalization of the substrates involves the physical immobilization of the nanorods onto the solid surface through the use of (3-mercaptopropyl)trimethoxysilane (MPTMS). The immobilization of the nanorods drastically increases their stability, allowing for use in complicated …

Go to article

Methodological Improvements In The Mrna Profiling Assays For Incorporation Into Dna Casework Workflows, Paris Volk May 2019

Methodological Improvements In The Mrna Profiling Assays For Incorporation Into Dna Casework Workflows, Paris Volk

Electronic Theses and Dissertations

Currently, DNA profiling is the gold standard to identify an individual. However, determining body fluid origin is important in criminal investigations, offering additional information surrounding the circumstances of a crime. However, crime labs can only definitively identify blood and semen and presumptively saliva using techniques that consume time and sample and do not simultaneously identify all forensically relevant body fluids. This causes many crime labs to want to bypass body fluid identification altogether. Therefore, advances into more definitive molecular-based body fluid methods are necessary. One such technique is mRNA profiling because it provides a highly sensitive and specific approach to …

Go to article

Synthetic Design And Characterization Of Polycyclic Aromatic Compounds In Molecular And Extended System, Gavin Pour May 2019

Synthetic Design And Characterization Of Polycyclic Aromatic Compounds In Molecular And Extended System, Gavin Pour

Electronic Theses and Dissertations

The work presented herein focuses on the synthesis and characterization of polycyclic aromatic compounds for a wide variety of toxicological, analytical, and electronic applications. First, the modular synthesis of 12 dibenzo- and naphtho- fluoranthene polycyclic aromatic hydrocarbons (PAHs) via a Pd-catalyzed five-membered ring closing procedure is discussed. By understanding the various modes through which the Pd migrates during transformation, structural rearrangements were bypassed, obtaining regioselectivity through various redesigns in the synthetic route. Each compound in the serious was rigorously characterized via 1D/2D NMR, absorption and emission spectroscopy as well as cyclic voltammetry, which shows vast differences due to small structural …

Go to article

Student Community Detection And Recommendation Of Customized Paths To Reinforce Academic Success, Yuan Shao May 2019

Student Community Detection And Recommendation Of Customized Paths To Reinforce Academic Success, Yuan Shao

Electronic Theses and Dissertations

Educational Data Mining (EDM) is a research area that analyzes educational data and extracts interesting and unique information to address education issues. EDM implements computational methods to explore data for the purpose of studying questions related to educational achievements. A common task in an educational environment is the grouping of students and the identification of communities that have common features. Then, these communities of students may be studied by a course developer to build a personalized learning system, promote effective group learning, provide adaptive contents, etc. The objective of this thesis is to find an approach to detect student communities …

Go to article

Engineering Noble-Metal Nanostructures For Biosensing Applications, Haihang Ye May 2019

Engineering Noble-Metal Nanostructures For Biosensing Applications, Haihang Ye

Electronic Theses and Dissertations

The ability to engineer noble-metal nanostructures (NMNSs) in a controllable manner and to understand the structure-dependent properties greatly boost our knowledge in rational design of biosensing technologies. In particular, as a type of highly efficient peroxidase mimics, NMNSs hold promising potential to break through the bottleneck of conventional enzyme-based in vitro diagnostics. During the time of my Ph.D. study, I have successfully: 1) directed a two-step method involving seed-mediated growth and chemical etching for the synthesis of Ru nanoframes (RuNFs) with face-centered cubic crystal phase and enhanced catalytic activities; 2) demonstrated, for the first time, the inherent peroxidase-like activity of …

Go to article

Framework For Modeling Attacker Capabilities With Deception, Sharif Hassan May 2019

Framework For Modeling Attacker Capabilities With Deception, Sharif Hassan

Electronic Theses and Dissertations

In this research we built a custom experimental range using opensource emulated and custom pure honeypots designed to detect or capture attacker activity. The focus is to test the effectiveness of a deception in its ability to evade detection coupled with attacker skill levels. The range consists of three zones accessible via virtual private networking. The first zone houses varying configurations of opensource emulated honeypots, custom built pure honeypots, and real SSH servers. The second zone acts as a point of presence for attackers. The third zone is for administration and monitoring. Using the range, both a control and participant-based …

Go to article

Quality Diversity: Harnessing Evolution To Generate A Diversity Of High-Performing Solutions, Justin Pugh May 2019

Quality Diversity: Harnessing Evolution To Generate A Diversity Of High-Performing Solutions, Justin Pugh

Electronic Theses and Dissertations

Evolution in nature has designed countless solutions to innumerable interconnected problems, giving birth to the impressive array of complex modern life observed today. Inspired by this success, the practice of evolutionary computation (EC) abstracts evolution artificially as a search operator to find solutions to problems of interest primarily through the adaptive mechanism of survival of the fittest, where stronger candidates are pursued at the expense of weaker ones until a solution of satisfying quality emerges. At the same time, research in open-ended evolution (OEE) draws different lessons from nature, seeking to identify and recreate processes that lead to the type …

Go to article

A Deep Learning Approach To Diagnosing Schizophrenia, Justin Barry May 2019

A Deep Learning Approach To Diagnosing Schizophrenia, Justin Barry

Electronic Theses and Dissertations

In this article, the investigators present a new method using a deep learning approach to diagnose schizophrenia. In the experiment presented, the investigators have used a secondary dataset provided by National Institutes of Health. The aforementioned experimentation involves analyzing this dataset for existence of schizophrenia using traditional machine learning approaches such as logistic regression, support vector machine, and random forest. This is followed by application of deep learning techniques using three hidden layers in the model. The results obtained indicate that deep learning provides state-of-the-art accuracy in diagnosing schizophrenia. Based on these observations, there is a possibility that deep learning …

Go to article

Realtime Editing In Virtual Reality For Room Scale Scans, Charles Greenwood May 2019

Realtime Editing In Virtual Reality For Room Scale Scans, Charles Greenwood

Electronic Theses and Dissertations

This work presents a system for the design and implementation of tools that support the editing of room-scale scans within a virtual reality environment, in real time. The moniker REVRRSS ("reverse") thus stands for Real-time Editing (in) Virtual Reality (of) Room Scale Scans. The tools were evaluated for usefulness based upon whether they meet the criterion of real time usability. Users evaluated the editing experience with traditional keyboard-video-mouse compared to a head mounted display and hand-held controllers for Virtual Reality. Results show that users prefer the VR approach. The quality of the finished product when using VR is comparable to …

Go to article

Novel Fuel-Producing Fungi And Methodologies For Increasing Fuel Production, Yuemin Wang Kovaleff May 2019

Novel Fuel-Producing Fungi And Methodologies For Increasing Fuel Production, Yuemin Wang Kovaleff

Electronic Theses and Dissertations

An endophytic fungus Hypoxylon sp. (BS15) has recently been isolated and found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. In the work described here, the traditional refined carbohydrate (e.g., sucrose) diet source was replaced by simple sugars produced using a solvent free green chemistry mechanocatalytic method involving ball milling in the solid. BS15 is able to grow on this degraded cellulose as well as the more traditional potato dextrose broth. The volatile compounds produced from both media were largely the same. Unfortunately, it is observed that long term in vitro growth of BS15 results …

Go to article

Transparency And Communication Patterns In Human-Robot Teaming, Shan Lakhmani May 2019

Transparency And Communication Patterns In Human-Robot Teaming, Shan Lakhmani

Electronic Theses and Dissertations

In anticipation of the complex, dynamic battlefields of the future, military operations are increasingly demanding robots with increased autonomous capabilities to support soldiers. Effective communication is necessary to establish a common ground on which human-robot teamwork can be established across the continuum of military operations. However, the types and format of communication for mixed-initiative collaboration is still not fully understood. This study explores two approaches to communication in human-robot interaction, transparency and communication pattern, and examines how manipulating these elements with a robot teammate affects its human counterpart in a collaborative exercise. Participants were coupled with a computer-simulated robot to …

Go to article

Lattice-Valued T-Filters And Induced Structures, Frederick Reid May 2019

Lattice-Valued T-Filters And Induced Structures, Frederick Reid

Electronic Theses and Dissertations

A complete lattice is called a frame provided meets distribute over arbitrary joins. The implication operation in this context plays a central role. Intuitively, it measures the degree to which one element is less than or equal to another. In this setting, a category is defined by equipping each set with a T-convergence structure which is defined in terms of T-filters. This category is shown to be topological, strongly Cartesian closed, and extensional. It is well known that the category of topological spaces and continuous maps is neither Cartesian closed nor extensional. Subcategories of compact and of complete spaces are …

Go to article

Efficient String Graph Construction Algorithm, S.M. Iqbal Morshed May 2019

Efficient String Graph Construction Algorithm, S.M. Iqbal Morshed

Electronic Theses and Dissertations

In the field of genome assembly research where assemblers are dominated by de Bruijn graph-based approaches, string graph-based assembly approach is getting more attention because of its ability to losslessly retain information from sequence data. Despite the advantages provided by a string graph in repeat detection and in maintaining read coherence, the high computational cost for constructing a string graph hinders its usability for genome assembly. Even though different algorithms have been proposed over the last decade for string graph construction, efficiency is still a challenge due to the demand for processing a large amount of sequence data generated by …

Go to article

A Theoretical Investigation Of Small Organic Molecules On Transition Metal Surfaces, Walter Malone May 2019

A Theoretical Investigation Of Small Organic Molecules On Transition Metal Surfaces, Walter Malone

Electronic Theses and Dissertations

With the ever growing number of proposed desnity functional theory (DFT) functionals it becomes necessary to thoroughly screen any new method to determine its merit. Especially relevant methods include a proper description of the van der Waals (vdW) interaction, which can prove vital to a correct description of a myriad of systems of technological importance. The first part of this dissertation explores the utility of several vdW-inclusive DFT functionals including optB86b-vdW, optB88-vdW, optPBE-vdW, revPBE-vdW, rPW86-vdW2, and SCAN+rVV10 by applying them to model systems of small organic molecules, pyridine and thiophene, on transition metal surfaces. Overall, we find the optB88-vdW functional …

Go to article

Chemistry And Structure Of Ru/Sio2 And Ru/Al2o3 Interfaces, Sameer Ezzat May 2019

Chemistry And Structure Of Ru/Sio2 And Ru/Al2o3 Interfaces, Sameer Ezzat

Electronic Theses and Dissertations

The resistivity size effect in nanoscale metals is of both scientific and technological interest, the latter due to its importance to interconnects between transistors in integrated circuits. In this work we report the variation of resistivity associated with surface scattering of ex-situ annealed single crystal Ru thin films grown on sapphire substrates by sputter deposition. A set of samples were overcoated with dielectric and subjected to a variety of reducing and oxidizing anneals. The changes in the chemistry and structure of the dielectric interface induced by the anneals, as determined by x-ray reflectivity and x-ray photoelectron spectroscopy measurements, are related …

Go to article

Analysis Of Hydrodynamic And Bathymetric Gradients In Canaveral National Seashore Following Living Shoreline And Oyster Restorations, David Spiering May 2019

Analysis Of Hydrodynamic And Bathymetric Gradients In Canaveral National Seashore Following Living Shoreline And Oyster Restorations, David Spiering

Electronic Theses and Dissertations

Coastal vulnerability has been gaining recognition as a critical issue, especially with the increasing predictions of sea level rise. Susceptibility to extreme events, eutrophication, and shoreline modification has left many coastal regions in a degraded state. Shoreline protection has traditionally taken the form of seawalls and offshore breakwaters which can be detrimental to both the local ecosystems and adjoining shorelines. The objective of this thesis is to analyze the hydrodynamic and bathymetric variation that occurs within Mosquito Lagoon, Florida following living shoreline and oyster reef restorations. The shoreline sites were sampled using a Before-After-Control-Impact (BACI) design and data were analyzed …

Go to article

Leaning Robust Sequence Features Via Dynamic Temporal Pattern Discovery, Hao Hu May 2019

Leaning Robust Sequence Features Via Dynamic Temporal Pattern Discovery, Hao Hu

Electronic Theses and Dissertations

As a major type of data, time series possess invaluable latent knowledge for describing the real world and human society. In order to improve the ability of intelligent systems for understanding the world and people, it is critical to design sophisticated machine learning algorithms for extracting robust time series features from such latent knowledge. Motivated by the successful applications of deep learning in computer vision, more and more machine learning researchers put their attentions on the topic of applying deep learning techniques to time series data. However, directly employing current deep models in most time series domains could be problematic. …

Go to article

Predicting Students' Academic Performance With Decision Tree And Neural Network, Junshuai Feng May 2019

Predicting Students' Academic Performance With Decision Tree And Neural Network, Junshuai Feng

Electronic Theses and Dissertations

Educational Data Mining (EDM) is a developing research field that involves many techniques to explore data relating to educational background. EDM can analyze and resolve educational data with computational methods to address educational questions. Similar to EDM, neural networks have been utilized in widespread and successful data mining applications. In this paper, synthetic datasets are employed since this paper aims to explore the methodologies such as decision tree classifiers and neural networks to predict student performance in the context of EDM. Firstly, it introduces EDM and some relative works that have been accomplished previously in this field along with their …

Go to article

Biogeochemical Effects Of Sea Level Rise-Induced Transitions Within Coastal Wetlands, Havalend Steinmuller May 2019

Biogeochemical Effects Of Sea Level Rise-Induced Transitions Within Coastal Wetlands, Havalend Steinmuller

Electronic Theses and Dissertations

As sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation shifts, and submergence were investigated. Changes in nutrient dynamics associated with saltwater intrusion were evaluated by artificially adding saline water to different freshwater wetland soil types, indicating that potential exports of critical nutrients (forms of nitrogen, phosphorus, and …

Go to article

Chemistry And Dissipation At Mineral Surfaces In The Space Environment, William Tucker May 2019

Chemistry And Dissipation At Mineral Surfaces In The Space Environment, William Tucker

Electronic Theses and Dissertations

The composition and morphology of mineral surfaces is known to play an important role in various phenomena relevant to planetary science. For example, the synthesis and processing of complex organics likely occurs at mineral surfaces strongly affected by the space environment. Furthermore, the dissipative and adhesive properties of dust grains may depend strongly on the chemical state of the surface including the presence of dangling bonds, adsorbates, and radicals. In this dissertation, experimental results are first presented which demonstrate that mineral grains subjected to high temperatures in a reducing environment lead to iron nanoparticles which are strongly catalytic for the …

Go to article

Determining The Influence Of Lateral Margin Mechanical Properties On Glacial Flow, Kate Hruby May 2019

Determining The Influence Of Lateral Margin Mechanical Properties On Glacial Flow, Kate Hruby

Electronic Theses and Dissertations

The lateral margins of glaciers and ice streams play a significant role in glacial flow. Depending on their properties, like temperature and ice crystal orientation, they can cause a resistance to flow or enhance it. In combination with our current changing climate, flow patterns can dictate the mass balance of an ice body. It is therefore more important than ever to understand the impact that variations at the margins can have on flow. However, the lateral margins of glaciers and ice streams are an often-neglected part of ice dynamics; they are harder to sample than the center of a glacier’s …

Go to article

Ecological And Economic Implications Of Increased Storm Frequency And Severity For Boreal Lakes, Kathryn Warner May 2019

Ecological And Economic Implications Of Increased Storm Frequency And Severity For Boreal Lakes, Kathryn Warner

Electronic Theses and Dissertations

In boreal regions, increased precipitation events have been linked to increased concentrations of dissolved organic carbon (DOC), however less is known about the extent and implications of these events on lakes. We assessed the effects of precipitation events on six drinking water lakes in Maine, USA to better understand how DOC concentration and quality change in response to precipitation events. Our results revealed three types of responses: (1) an initial spike in DOC concentrations and quality metrics; (2) a sustained increase in DOC concentrations and quality metrics and; (3) no change during all sampling periods. Lake residence time was a …

Go to article

Federal, State And Local Law Enforcement Agency Interoperability Capabilities And Cyber Vulnerabilities, Tyrone Trapnell May 2019

Federal, State And Local Law Enforcement Agency Interoperability Capabilities And Cyber Vulnerabilities, Tyrone Trapnell

Electronic Theses and Dissertations

The National Data Exchange (N-DEx) System is the central informational hub located at the Federal Bureau of Investigation (FBI). Its purpose is to provide network subscriptions to all Federal, state and local level law enforcement agencies while increasing information collaboration across all domains. The National Data Exchange users must satisfy the Advanced Permission Requirements, confirming the terms of N-DEx information use, and the Verification Requirement (verifying the completeness, timeliness, accuracy, and relevancy of N-DEx information) through coordination with the record-owning agency (Management, 2018). A network infection model is proposed to simulate the spread impact of various cyber-attacks within Federal, state …

Go to article

First Prev Next Last