Physical Sciences and Mathematics Commons^™

Averaged Instrumental Variables Estimators, Yoonseok Lee, Yu Zhou

Center for Policy Research

We develop averaged instrumental variables estimators as a way to deal with many weak instruments. We propose a weighted average of the preliminary k-class estimators, where each estimator is obtained using different subsets of the available instrumental variables. The averaged estimators are shown to be consistent and to satisfy asymptotic normality. Furthermore, its approximate mean squared error reveals that using a small number of instruments for each preliminary k-class estimator reduces the finite sample bias, while averaging prevents the variance from inflating. Monte Carlo simulations find that the averaged estimators compare favorably with alternative instrumental-variable-selection approaches when the strength levels …

Modeling Seed Dispersal And Population Migration Given A Distribution Of Seed Handling Times And Variable Dispersal Motility: Case Study For Pinyon And Juniper In Utah, Ram C. Neupane

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The spread of fruiting tree species is strongly determined by the behavior and range of fruit-eating animals, particularly birds. Birds either consume and digest seeds or carry and cache them at some distance from the source tree. These carried and settled seeds provide some form of distribution which generates tree spread to the new location. Firstly, we modal seed dispersal by birds and introduce it in a dispersal model to estimate seed distribution. Using this distribution, we create a population model to estimate the speed at which juniper and pinyon forest boundaries move.

Secondly, we introduce a fact that bird …

Practicing Good Stewardship When Applying Herbicides For Pasture Weed Control, Jonathan D. Green

Agriculture and Natural Resources Publications

Various methods and strategies can be used to combat weed problems in pasture fields. These include mechanical and cultural practices such as mowing or clipping fields, maintaining a good soil fertility program, grazing methods, and other management practices that promote the growth of desirable forage grasses which in turn compete against weeds. Herbicides can be the best alternative to effectively control several troublesome broadleaf weeds. However, it is important to understand the proper use of herbicides and practice good stewardship. Below are some important tips to consider when choosing and applying a herbicide product.

Aquatic Macroinvertebrates: Biological Indicators Of Stream Health, Carmen T. Agouridis, Evan T. Wesley, Tyler M. Sanderson, Blake L. Newton

Agriculture and Natural Resources Publications

Streams are an important part of the landscape. Streams transport water, sediment and energy; provide habitat for aquatic life and support terrestrial life; provide a place for recreation; and in many cases serve as a water supply. The health of streams—or their ability to perform these important functions—is dependent on the conditions of the watersheds which they drain. Changes in land use within a watershed can affect a stream’s health (Figure 1).

Measuring Biological Cell Damage Due To Ionizing Radiation, Kathryn Jacobson

Honors Theses, 1963-2015

Radiation therapy is used to treat many different types of cancer. Ionizing radiation occurs at very high frequencies and can cause reparable or permanent damage to biological cells. Cancerous tumors are typically located behind layers of healthy tissue and when radiated, the healthy and cancerous cells are damaged. With new technology, radiation machines deliver radiation such that the tissue damage is uniform as a function of tissue depth by filtering out the low-energy photons. The purpose of this research was to determine the validity of using the change in dielectric constant to gauge tissue damage due to radiation. The change …

Extreme Value Theory And Backtest Overfitting In Finance, Daniel C. Byrnes

Honors Projects

In order to identify potentially profitable investment strategies, hedge funds and asset managers can use historical market data to simulate a strategy's performance, a process known as backtesting. While the abundance of historical stock price data and powerful computing technologies has made it feasible to run millions of simulations in a short period of time, this process may produce statistically insignificant results in the form of false positives. As the number of configurations of a strategy increases, it becomes more likely that some of the configurations will perform well by chance alone. The phenomenon of backtest overfitting occurs when a …

Mathematical Notions Of Resilience: The Effects Of Disturbancei In One-Dimensional Nonlinear Systems, Stephen Ligtenberg

Honors Projects

No abstract provided.

Modeling Lake Michigan Nearshore Carbon And Phosphorus Dynamics, Joseph Henry Fillingham

Theses and Dissertations

Dreissenid mussels, in particular quagga mussels (Dreissena rostiformis bugensis), are transforming the Lake Michigan ecosystem by clearing the water column, recycling phosphorus and modifying benthic habitat. These impacts are thought to have caused observed declines in the spring phytoplankton bloom in Lake Michigan, as well as changes to food web structure and declines in the abundance of critical invertebrate and fish species. In the nearshore zone, the resurgence of benthic Cladophora algae to nuisance levels not observed since phosphorus loading abatement policies instituted in the 1970s has also been attributed to water column clearing and phosphorus recycling by mussels. Using …

Sustainable Decolorization Of Reactive And Acid Dye Wastewater Using Photo-Fenton Oxidation Both With And Without Biodegradation: Laboratory And Field Studies, Marissa R. Jablonski

Theses and Dissertations

Photo-Fenton oxidation is an advanced oxidation process (AOP) used to degrade low-concentration textile dye wastewater using expensive chemicals. The technique has shown promise in laboratory-scale projects, but has not been scaled up sustainably to function for industry. Aerobic biodegradation is a common biological treatment method used in large-scale textile industrial applications that generates large amounts of hazardous biological waste. This waste is often left open to the elements and subsequently leaches into natural waterways or onto land. This is the first study of its kind to combine the two to treat cottage-scale industry-grade textile wastewater with a dye concentration of …

Multiple Generations Of Faulting: A Kinematic Analysis Of The Lagarfljót Region, Northeast Iceland, Keegan Runnals

Theses - ALL

The North American/Eurasian plate boundary in Iceland is structurally diverse with oblique rifts, volcanic fissure swarms, and transform zones, and a hotspot. Lagarfljót is a lake located in the Tertiary flood basalts of East Iceland, that range in age from ~7 to 3 Ma. The lake is approximately 50 km east of the actively spreading, NS-trending, Northern Rift Zone (NVZ), and occupies a northeast-trending depression in an area of strong NS lineaments. A flexure zone, or zone of steeply dipping lavas, runs N-S across the southern part of the lake, and predates an angular unconformity in the regional lava pile. …

Tio 2 Fibers: Tunable Polymorphic Phase Transformation And Electrochemical Properties, Edna Garcia, Qiang Li, Xing Sun, Karen Lozano, Yuanbing Mao

Chemistry Faculty Publications and Presentations

A series of one-dimensional (1D) nanoparticle-assembled TiO2 fibers with tunable polymorphs were prepared via a novel and large scale ForceSpinning® process of titanium tetraisopropoxide (TTIP)/polyvinylpyrrolidone (PVP) precursor fibers followed with a thermal treatment at various calcinations temperatures. The thermal and structural transformations were characterized by thermogravimetric analysis/differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction. The influence of polymorphic phase of the TiO2 fibers on the electrochemical performance in neutral aqueous 1 M Na2SO4 electrolyte was investigated. The polymorphic amorphous/anatase/rutile TiO2 fibers prepared at 450 °C achieved a highest capacitance of 21.2 F g−1 (6.61 mF cm−2) at a current …

Monitoring Invasive Plant Species: Summer Internship At Habitat Wildlife Sanctuary, Belmont, Massachusetts, Holly M. Zanoni

Sustainability and Social Justice

Habitat Wildlife Sanctuary, located in Belmont, Massachusetts is a dynamic suburban sanctuary that effectively upholds Mass Audubon’s three-part mission of advocacy, conservation, and education. Invasive plants threaten ecological integrity; however, proactive measures are taken to mitigate further encroachment. This is accomplished by surveying and taking inventory for presence of invasive species, then prioritizing them, and finally by incorporating high priority species into the immediate management strategy. Four invasive plants were formally analyzed using geographic information science during the 2014 growing season: Garlic mustard, Black swallowwort, Japanese knotweed, and Dame’s Rocket. The resulting density maps detected pattern changes from 2011, 2012, …

Exploring Ways Of Identifying Outliers In Spatial Point Patterns, Jie Liu

Electronic Theses and Dissertations

This work discusses alternative methods to detect outliers in spatial point patterns.

Outliers are defined based on location only and also with respect to associated variables. Throughout the thesis we discuss five case studies, three of them come from experiments with spiders and bees, and the other two are data from earthquakes in a certain region. One of the main conclusions is that when detecting outliers from the point of view of location we need to take into consideration both the degree of clustering of the events and the context of the study. When detecting outliers from the point of …

The Relationship Between Motivation And Volunteer Satisfaction In Conservation Programs 2015., Raena Blumenthal

Master's Theses

Conservation leisure service organizations are relying more heavily on volunteers to sustain their services and protect natural resources (Strigas, 2006). However, research focusing on volunteer vacationers, those who spend money to volunteer, is still in its infancy. Drawing on functional theorizing (Bruyer & Rappe, 2007; Clary, Snyder, Ridge, Copeland, Stukas, Haugen, & Miene, 1998; Houle, Sagarin, & Kaplan, 2005; Katz, 1960; Smith, Bruner, & White, 1956), this study explored volunteer vacationers’ motivations and the relationships between motivations to volunteer, satisfaction with the volunteer vacation experience, and inclinations to volunteer in the future (in both local and nonlocal settings). The study …

Breaking The News: First Impressions Matter On Online News, Julio Reis, Fabr´Icio Benevenuto, Pedro Olmo, Raquel Prates, Haewoon Kwak, Jisun An

Research Collection School Of Computing and Information Systems

A growing number of people are changing the way they consume news, replacing the traditional physical newspapers and magazines by their virtual online versions or/and weblogs. The interactivity and immediacy present in online news are changing the way news are being produced and exposed by media corporations. News websites have to create effective strategies to catch people’s attention and attract their clicks. In this paper we investigate possible strategies used by online news corporations in the design of their news headlines. We analyze the content of 69,907 headlines produced by four major global media corporations during a minimum of eight …

Efficient Reverse Top-K Boolean Spatial Keyword Queries On Road Networks, Yunjun Gao, Xu Qin, Baihua Zheng, Gang Chen

Research Collection School Of Computing and Information Systems

Reverse k nearest neighbor (RkNN) queries have a broad application base such as decision support, profile-based marketing, and resource allocation. Previous work on RkNN search does not take textual information into consideration or limits to the Euclidean space. In the real world, however, most spatial objects are associated with textual information and lie on road networks. In this paper, we introduce a new type of queries, namely, reverse top-k Boolean spatial keyword (RkBSK) retrieval, which assumes objects are on the road network and considers both spatial and textual information. Given a data set P on a road network and a …

Accuracy Of Supervised Classification Of Cropland In Sub–Saharan Africa, Sarah Lynn Lewis-Gonzales

Masters Theses

Mali is a country in sub–Saharan Africa where monitoring of cropped land area would greatly benefit food security initiatives and aid organizations. More importantly village–scale studies on cropped land are fundamental to making a difference in the way we look at cropped land area and food availability in this region of the world. Using Landsat surface reflectance imagery and World View–2 derived labeled data, this study focuses on accuracy of supervised classification methods while addressing various levels of scale. Several classification methods are taken into account to determine the best method possible to produce cropped area estimates using this data. …

Phase Dynamics Of Locset Control Methodology, Brendan Neschke

Masters Theses

Single-mode fiber amplifiers produce diffraction-limited beams very efficiently. Maximum beam intensity requires that an array of these amplifiers have their beams coherently combined at the target. Optical path differences and noise adversely affect beam quality. An existing closed loop phase control methodology, called the locking of optical coherence by single-detector electronic-frequency tagging (LOCSET), corrects phase errors in real time by electronically detecting path length differences and sending signals to lithium niobate phase adjusters. Broadening the line-width using “jitter” of the input signal can increase the output power of an individual amplifier by suppressing nonlinearity. The system dynamics of LOCSET are …

Fake And Spam Messages: Detecting Misinformation During Natural Disasters On Social Media, Meet Rajdev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

During natural disasters or crises, users on social media tend to easily believe contents of postings related to the events, and retweet the postings, hoping that the postings will be reached by many other users. Unfortunately, there are malicious users who understand the tendency and post misinformation such as spam and fake messages with expecting wider propagation. To resolve the problem, in this paper we conduct a case study of the 2013 Moore Tornado and Hurricane Sandy. Concretely, we (i) understand behaviors of these malicious users; (ii) analyze properties of spam, fake and legitimate messages; (iii) propose flat and hierarchical …

Tropical Arithmetics And Dot Product Representations Of Graphs, Nicole Turner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In tropical algebras we substitute min or max for the typical addition and then substitute addition for multiplication. A dot product representation of a graph assigns each vertex of the graph a vector such that two edges are adjacent if and only if the dot product of their vectors is greater than some chosen threshold. The resultS of creating dot product representations of graphs using tropical algebras are examined. In particular we examine the tropical dot product dimensions of graphs and establish connections to threshold graphs and the threshold dimension of a graph.

Annotation Tools For Multivariate Gene Set Testing Of Non-Model Organisms, Russell K. Banks

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Microarray chip technology enables researchers to obtain measures of gene activity for essentially all genes in an organism. After grouping genes into biologically meaningful sets, researchers employ certain statistical tests to identify which gene sets (biological processes) show different levels of activity across different treatment groups. The idea is to identify which biological processes are significantly affected by a certain treatment/condition in a given organism.

Non-model organisms (such as sheep) are not widely studied so gene set membership information is not always readily accessible. This thesis work utilizes two microarray studies involving sheep to provide researchers with working examples of …

Relative Toxicity Of Select Dehydropyrrolizidine Alkaloids And Evaluation Of A Heterozygous P53 Knockout Mouse Model For Dehydropyrrolizidine Alkaloid Induced Carcinogenesis, Ammon W. Brown

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dehydropyrrolizidine alkaloids (DHPAs) are toxins produced by approximately 3% of the world’s flowering plants that can be present naturally or as contaminants in animal feed and the human food supply. Many of these compounds have been determined to cause cancer in animals and probably also cause cancer in humans. Due to the difficulty in obtaining sufficient amounts of pure DHPAs most toxicity research has been done via injection of a small amount into the abdomen of a rodent, although natural exposure is exclusively oral. For the same reason, cancer research is limited to a handful of the hundreds of known …

Digital Soil Mapping Using Landscape Stratification For Arid Rangelands In The Eastern Great Basin, Central Utah, Brook B. Fonnesbeck

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In some parts of the western US there is limited publicly available soil information that can be used to make land management decisions on both public and private land. A goal of the USDI Bureau of Land Management (BLM) in Utah was to map an area in central Utah where such soil maps and value-added information was not available for management and restoration decisions following a wildfire. In 2007, the Milford Flat Fire had burned more than 363,000 acres, removing vegetation that was holding erosion-sensitive soils in place. Following inconsistent results from stabilization and restoration efforts, this study was funded …

Algorithmic Information Theory Applications In Bright Field Microscopy And Epithelial Pattern Formation, Hamid Mohamadlou

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The incredible patterns of multicellular organisms emerge as a result of the operation of Gene Regulatory Networks (GRN) that work during development. Understanding how GRNs produce these complex multicellular patterns is a significant challenge in biology. The primary goal of this dissertation is to employ Algorithmic Information Theory (AIT), also known as Kolmogorov complexity, to unravel the information complexity of GRNs and the resultant multicellular patterns. To obtain a better understanding of Kolmogorov complexity performance, first we study an application in cell image segmentation.

There are an estimated 20,000-25,000 protein-coding genes in the human genome. The sheer size of the …

Sequence Stratigraphy, Depositional Environments And Geochemistry Of The Middle Cambrian Bloomington Formation In Northern Utah, Christopher Ryan Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Bloomington Formation (~425 m thick) is a latest Middle Cambrian (~506.5-505 Ma.), mixed warm water, carbonate and shale unit on the Cordilleran passive margin in northern Utah and southern Idaho. The Hodges Shale and Calls Fort Shale Members are shale dominated and the Middle Limestone Member is a thick carbonate. Fossil diversity and abundance is surprisingly low for a Middle Cambrian carbonate/shale formation. Present, however, are 10-50 cm thrombolite mud mounds, associated with Girvanella oncoliths. These mud mounds represent shallow water carbonates that experienced a small flooding event that gives the mud mounds time and proper conditions to build …

Decision Environments To Encourage More Sustainable Infrastructure Outcomes, Earl Shealy

All Dissertations

Physical infrastructure (i.e. roads, pipelines, airports, dams, landfills, and water treatment systems) contributes directly to sustainability outcomes such as energy and water use and climate changing emissions. The infrastructure built today will likely impact future generations for many years. Planning, design and development decisions about infrastructure are critical to the future performance of these systems. Such decisions about infrastructure are complex with multiple variables, alternative options, and design stages. To manage decisions that exceed cognitive capacity to consider all options, decision makers often create mental shortcuts (heuristics), and accompanied errors (biases). The potential cognitive biases when dealing with complex decisions …

Linking Form And Process In Braided Rivers Using Physical And Numerical Models, Alan Kasprak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Braided rivers are characterized by their dynamic nature, and are often significantly reshaped during each flood capable of transporting sediment. Over time, they adjust in response to the frequency and magnitude of floods, along with the amount of sediment available for bar building. Factors such as climate change, dam construction, or land use alteration that change the amount of sediment or water available to braided rivers may subsequently affect channel form. One avenue toward understanding braided channel evolution is to develop simple relationships between channel form and sediment transport, and extrapolate those relationships over extended timescales. With funding from the …

Tunable Negative Permeability In A Three-Dimensional Superconducting Metamaterial, Cihan Kurter, T. Lan, L. Sarytchev, Steven Mark Anlage

Physics Faculty Research & Creative Works

We report on highly tunable radio-frequency (rf) characteristics of a low-loss and compact three-dimensional (3D) metamaterial made of superconducting thin-film spiral resonators. The rf transmission spectrum of a single element of the metamaterial shows a fundamental resonance peak at ~24.95 MHz that shifts to a 25% smaller frequency and becomes degenerate when a 3D array of such elements is created. The metamaterial shows an in situ tunable narrow frequency band in which the real part of the effective permeability is negative over a wide range of temperature. This narrow frequency band gradually possesses near-zero and positive values for the real …

Efficient Variations Of The Quality Threshold Clustering Algorithm, Frank Loforte Jr.

CCE Theses and Dissertations

Clustering gene expression data such that the diameters of the clusters formed are no greater than a specified threshold prompted the development of the Quality Threshold Clustering (QTC) algorithm. It iteratively forms clusters of non-increasing size until all points are clustered; the largest cluster is always selected first. The QTC algorithm applies in many other domains that require a similar quality guarantee based on cluster diameter. The worst-case complexity of the original QTC algorithm is (n5). Since practical applications often involve large datasets, researchers called for more efficient versions of the QTC algorithm.

This dissertation aimed to develop …

An Empirical Development Of Critical Value Factors For System Quality And Information Quality In Business Intelligence Systems Implementations, Paul Dooley

CCE Theses and Dissertations

Business intelligence (BI) systems have been widely recognized as a leading technology for many years. However, despite the high priority and importance placed on BI, there has been a significant lack of BI system implementation (BISI) success. BI systems are not considered to be conventional information systems (IS) and often rely on the integration of a complex information infrastructure. Consequently, the degree of information quality (IQ) and system quality (SQ) have not met expectations for BISI success.

This study was designed to determine how an organization may gain benefits in the context of BISI by uncovering the antecedents and critical …