Local Hemodynamic Conditions Associated With Focal Changes In The Intracranial Aneurysm Wall,
2019
George Mason University
Local Hemodynamic Conditions Associated With Focal Changes In The Intracranial Aneurysm Wall, Juan R. Cebral, F. Detmer, Bong Jae Chung, J. Choque-Velasquez, B. Rezai, H. Lehto, R. Tulamo, J. Hernesniemi, M. Niemela, A. Yu, R. Williamson, Khaled Aziz, S. Sakur, S. Amin-Hanjani, F. Charbel, Y. Tobe, A. Robertson, J. Frösen
Department of Applied Mathematics and Statistics Faculty Scholarship and Creative Works
BACKGROUND AND PURPOSE: Aneurysm hemodynamics has been associated with wall histology and inflammation. We investigated associations between local hemodynamics and focal wall changes visible intraoperatively. MATERIALS AND METHODS: Computational fluid dynamics models were constructed from 3D images of 65 aneurysms treated surgically. Aneurysm regions with different visual appearances were identified in intraoperative videos: 1) “atherosclerotic” (yellow), 2) “hyperplastic” (white), 3) “thin” (red), 4) rupture site, and 5) “normal” (similar to parent artery), They were marked on 3D reconstructions. Regional hemodynamics was characterized by the following: wall shear stress, oscillatory shear index, relative residence time, wall shear stress gradient and divergence, …
The Use Of 3-D Highway Differential Geometry In Crash Prediction Modeling,
2019
University of Kentucky
The Use Of 3-D Highway Differential Geometry In Crash Prediction Modeling, Kiriakos Amiridis
Theses and Dissertations--Civil Engineering
The objective of this research is to evaluate and introduce a new methodology regarding rural highway safety. Current practices rely on crash prediction models that utilize specific explanatory variables, whereas the depository of knowledge for past research is the Highway Safety Manual (HSM). Most of the prediction models in the HSM identify the effect of individual geometric elements on crash occurrence and consider their combination in a multiplicative manner, where each effect is multiplied with others to determine their combined influence. The concepts of 3-dimesnional (3-D) representation of the roadway surface have also been explored in the past aiming to …
Fixed Choice Design And Augmented Fixed Choice Design For Network Data With Missing Observations,
2019
Smith College
Fixed Choice Design And Augmented Fixed Choice Design For Network Data With Missing Observations, Miles Q. Ott, Matthew T. Harrison, Krista J. Gile, Nancy P. Barnett, Joseph W. Hogan
Statistical and Data Sciences: Faculty Publications
The statistical analysis of social networks is increasingly used to understand social processes and patterns. The association between social relationships and individual behaviors is of particular interest to sociologists, psychologists, and public health researchers. Several recent network studies make use of the fixed choice design (FCD), which induces missing edges in the network data. Because of the complex dependence structure inherent in networks, missing data can pose very difficult problems for valid statistical inference. In this article, we introduce novel methods for accounting for the FCD censoring and introduce a new survey design, which we call the augmented fixed choice …
Finite Mixture Of Regression Models For Complex Survey Data,
2019
South Dakota State University
Finite Mixture Of Regression Models For Complex Survey Data, Abdelbaset Abdalla
Electronic Theses and Dissertations
Over time, survey data has become an essential source of information for modern society. However, to be effective, the structures of survey data require sampling designs that are more complex than simple random sampling. The complex sampling data collected from enormous national surveys via these complex designs ideally include sample weights that allow analysis to take account of complicated population structures. When the target of inference is the parameters of a regression model, it is crucial to know whether these weights should be incorporated into the sampling weight when fitting the model to the survey data. The finite mixture models …
Performance Measurement In Maine’S Social Sector: The Intersection Of Philanthropy And Nonprofits,
2019
The Data Innovation Project
Performance Measurement In Maine’S Social Sector: The Intersection Of Philanthropy And Nonprofits, Susy Hawes, Sarah Goan
Publications
The Data Innovation Project undertook this project to better understand foundations’ expectations of grantees in terms of performance measures and outcomes as outlined in their grant applications. Over the past two years, the Data Innovation Project has engaged with over 250 Maine nonprofits who are navigating the data reporting requirements of a diverse portfolio of funders with varying degrees of success and challenges. This paper looks more closely at how the important relationship between foundations and nonprofits may benefit from increased understanding and clarity around measurement approaches so that both dollars and efforts lead to meaningful and measureable results across …
Methods For Estimating Mountain Goat Occupancy And Abundance,
2019
University of Montana
Methods For Estimating Mountain Goat Occupancy And Abundance, Molly Mcdevitt
Graduate Student Theses, Dissertations, & Professional Papers
Abundance and occupancy are two parameters of central interest to the field of ecology. Furthermore, accurate (both precise and unbiased) estimates are key pieces to the puzzle of effective wildlife management decision-making. While there exist a variety of sampling techniques and statistical models for effectively estimating population parameters for frequently encountered and large mammals, methods for sampling unmarked and rare species are few and far between. The first step to acquiring usable parameter estimates is through the use of sampling theory and incorporation of probabilistic sampling designs to collect count-data and occurrence-data. Often, it is assumed that probabilistic sampling designs …
Spatiotemporal Dynamics Of Nitrogen And Carbon Biogeochemistry In A Wetland-Stream Sequence,
2019
University of Montana
Spatiotemporal Dynamics Of Nitrogen And Carbon Biogeochemistry In A Wetland-Stream Sequence, Patrick E. Hurley
Graduate Student Theses, Dissertations, & Professional Papers
Studies of aquatic ecosystems often segregate streams from the influential ponds, lakes, and wetland zones that act as important transitions between terrestrial and fluvial systems. Across the aquatic landscape, these zones interact to form linked ecosystems that function as discrete nutrient processing domains, shifting biogeochemical signals due to spatial and temporal variability in hydrologic and biologic controls. Using a mass-balance approach, we profiled nutrient dynamics along a 23-km wetland-stream sequence over three seasons. Hydrologic, morphologic, and biologic conditions, as well as landscape attributes, were quantified to determine potential controls on biogeochemical cycling in a tributary of the Upper Clark Fork …
High Dimensional Outlier Detection,
2019
University of Montana
High Dimensional Outlier Detection, Omid Khormali
Graduate Student Theses, Dissertations, & Professional Papers
In statistics and data science, outliers are data points that differ greatly from other observations in a data set. They are important attributes of the data because they can dramatically influence patterns and relationships manifested by non-outliers. It is therefore very important to detect and adequately deal with outliers. Recently, a novel algorithm, the ROMA algorithm, has been proposed [11]. In this paper, we propose a modification of the ROMA algorithm that reduces its computational complexity from $O(n^2 m)$ to $O((n/(2^m-o(1)))^2 m)$ where $n$ is the number of data points and $m$ is the dimension of the space. And as …
Biodiversity And Distribution Of Benthic Foraminifera In Harrington Sound, Bermuda: The Effects Of Physical And Geochemical Factors On Dominant Taxa,
2019
Colby College
Biodiversity And Distribution Of Benthic Foraminifera In Harrington Sound, Bermuda: The Effects Of Physical And Geochemical Factors On Dominant Taxa, Nam Le
Honors Theses
Harrington Sound, Bermuda, is a nearly enclosed lagoon acting as a subtropical/tropical, carbonate-rich basin in which carbonate sediments, reef patches, and carbonate-producing organisms accumulate. Here, one of the most important calcareous groups is the Foraminifera. Analyses of common benthic orders, including miliolids (Quinqueloculina and Triloculina spp.) and rotaliids (Homotrema rubrum, Elphidium spp., and Ammonia beccarii), are essential in understanding past and present environmental conditions affecting the island's coastal environment. These taxa have been studied previously; however, factors explaining their individual patterns of abundance in the Sound are not well detailed. The goal of this study is …
Bayesian Nonparametric Analysis Of Longitudinal Data With Non-Ignorable Non-Monotone Missingness,
2019
Virginia Commonwealth University
Bayesian Nonparametric Analysis Of Longitudinal Data With Non-Ignorable Non-Monotone Missingness, Yu Cao
Theses and Dissertations
In longitudinal studies, outcomes are measured repeatedly over time, but in reality clinical studies are full of missing data points of monotone and non-monotone nature. Often this missingness is related to the unobserved data so that it is non-ignorable. In such context, pattern-mixture model (PMM) is one popular tool to analyze the joint distribution of outcome and missingness patterns. Then the unobserved outcomes are imputed using the distribution of observed outcomes, conditioned on missing patterns. However, the existing methods suffer from model identification issues if data is sparse in specific missing patterns, which is very likely to happen with a …
Cramer Type Moderate Deviations For Random Fields And Mutual Information Estimation For Mixed-Pair Random Variables,
2019
University of Mississippi
Cramer Type Moderate Deviations For Random Fields And Mutual Information Estimation For Mixed-Pair Random Variables, Aleksandr Beknazaryan
Electronic Theses and Dissertations
In this dissertation we first study Cramer type moderate deviation for partial sums of random fields by applying the conjugate method. In 1938 Cramer published his results on large deviations of sums of i.i.d. random variables after which a lot of research has been done on establishing Cramer type moderate and large deviation theorems for different types of random variables and for various statistics. In particular results have been obtained for independent non-identically distributed random variables for the sum of independent random to estimate the mutual information between two random variables. The estimates enjoy a central limit theorem under some …
The Role Of Glucose Level On The Performance Of The Framingham Risk Score,
2019
Walden University
The Role Of Glucose Level On The Performance Of The Framingham Risk Score, Uohna June Thiessen
Walden Dissertations and Doctoral Studies
Cardiovascular diseases (CVD) are responsible for more deaths than any other disease, continue to threaten the quality of life for many, and is a major burden to the health care system. The Framingham Heart Study (FHS) identified the major CVD risk factors that became essential to effective CVD screening strategies and the Framingham Risk Score (FRS), is used to assess CVD risk. Based on the concepts of the health behavior model and CVD as a cardiometabolic disorder, multivariate logistic regression analysis was used to evaluate the association between fasting blood glucose (FBG) levels and a CHD event, and to determine …
A Geographic Study Of Lung And Bronchus Cancer Rates In Kentucky,
2019
Walden University
A Geographic Study Of Lung And Bronchus Cancer Rates In Kentucky, Gabriel Njoh Dikong
Walden Dissertations and Doctoral Studies
The average age-adjusted incidence and mortality rates of lung and bronchus cancer is 55% and 56% higher in Kentucky than the national averages in the United States, respectively. Populations with low income and educational attainment, and those who live close to the mining regions across Kentucky are more affected by the high prevalence and resulting mortality rates of lung and bronchus cancer. This study was conducted because of the high incidence of lung and bronchus cancer and resulting mortality rates in the state of Kentucky that may not be caused solely by social and demographic factors. The theoretical foundation for …
Development Of A Data-Driven Patient Engagement Score Using Finite Mixture Models,
2019
South Dakota State University
Development Of A Data-Driven Patient Engagement Score Using Finite Mixture Models, Eric Bae
Electronic Theses and Dissertations
Patient activation measure (PAM) is widely adopted by health care providers to access individual's knowledge, skill, and confidence for managing one's health and healthcare. Patient activation measure (PAM), licensed by Insignia Health, is widely adopted by health care providers to access individual's knowledge, skill, and confidence for managing one's health and healthcare. Multiple studies corroborate the effectiveness of activation measure in predicting most health behaviors, including preventive behaviors, healthy behaviors, self-management behaviors, and health information seeking. However, PAM is heavily dependent on subjective patient-reported data, which are often incomplete. The purpose of this study is to develop an objective statistical …
Quasilinearization And Boundary Value Problems At Resonance For Caputo Fractional Differential Equations,
2019
Qassim University
Quasilinearization And Boundary Value Problems At Resonance For Caputo Fractional Differential Equations, Saleh S. Almuthaybiri, Paul W. Eloe, Jeffrey T. Neugebauer
Mathematics Faculty Publications
The quasilinearization method is applied to a boundary value problem at resonance for a Caputo fractional differential equation. The method of upper and lower solutions is first employed to obtain the uniqueness of solutions of the boundary value problem at resonance. The shift argument is applied to show the existence of solutions. The quasilinearization algorithm is then developed and sequences of approximate solutions are constructed that converge monotonically and quadratically to the unique solution of the boundary value problem at resonance. Two applications are provided to illustrate the main results.
The Effect Of Neonicotinoids On Apis Mellifera: A Revisit,
2019
Eastern Michigan University
The Effect Of Neonicotinoids On Apis Mellifera: A Revisit, Qingchen Liang
Master's Theses and Doctoral Dissertations
Colony collapse disorder (CCD), which has caused high colony mortality rates in the European honeybee (Apis mellifera), is a pressing economical and ecological problem. I revisited Woodcock et al.'s (2017a) paper, "Country-specic Effects of Neonicotinoid Pesticides on Honey Bees and Wild Bees", in light of unsound statistical methods used in the original study. In the first part of this paper, I attempted to replicate the analysis underlying key findings in the original paper. In the second part, I reanalyzed the data using mostly non-parametric methods in order to obtain robust results. I did not find any evidence for a harmful …
Time-Reflective Text Representations For Semantic Evolution Tracking And Trend Analytics,
2019
University of Texas at El Paso
Time-Reflective Text Representations For Semantic Evolution Tracking And Trend Analytics, Roberto Camacho Barranco
Open Access Theses & Dissertations
The extraction of significant, relevant, and useful trends from massive document collections, such as a streaming newswire or scientific publications, is a challenging and significant problem in many different fields, including intelligence analysis, recommendation systems, and scientific research. However, techniques that tackle trend analytics of such large text corpora are limited because research that addresses the temporal nature of these publications is still in its early stages. In this work, we first show that it is possible to capture the evolution of a story (or trend) by connecting the dots between different documents in a text corpus. The observed results …
Robust And Adaptive Design Approaches For Stepped Wedge Cluster Randomized Trials,
2019
Southern Methodist University
Robust And Adaptive Design Approaches For Stepped Wedge Cluster Randomized Trials, Jijia Wang
Statistical Science Theses and Dissertations
The stepped wedge (SW) cluster randomized design has been increasingly employed by pragmatic trials in health services research. In this study, based on the GEE approach, I present a closed-form sample size that is applicable to both closed-cohort and cross-sectional SW trials with outcomes from the exponential family. On the other hand, I proposed a Bayesian adaptive design for cross-sectional SW cluster randomized trials. It is more adaptable than traditional designs because it allows early termination of the trial when interim data indicate that the intervention is sufficient efficacious or inefficacious. A decision to terminate or continue the trial will …
Estimation And Variable Selection In High-Dimensional Settings With Mismeasured Observations,
2019
Southern Methodist University
Estimation And Variable Selection In High-Dimensional Settings With Mismeasured Observations, Michael Byrd
Statistical Science Theses and Dissertations
Understanding high-dimensional data has become essential for practitioners across many disciplines. The general increase in ability to collect large amounts of data has prompted statistical methods to adapt for the rising number of possible relationships to be uncovered. The key to this adaptation has been the notion of sparse models, or, rather, models where most relationships between variables are assumed to be negligible at best. Driving these sparse models have been constraints on the solution set, yielding regularization penalties imposed on the optimization procedure. While these penalties have found great success, they are typically formulated with strong assumptions on the …
Modeling Stochastically Intransitive Relationships In Paired Comparison Data,
2019
Southern Methodist University
Modeling Stochastically Intransitive Relationships In Paired Comparison Data, Ryan Patrick Alexander Mcshane
Statistical Science Theses and Dissertations
If the Warriors beat the Rockets and the Rockets beat the Spurs, does that mean that the Warriors are better than the Spurs? Sophisticated fans would argue that the Warriors are better by the transitive property, but could Spurs fans make a legitimate argument that their team is better despite this chain of evidence?
We first explore the nature of intransitive (rock-scissors-paper) relationships with a graph theoretic approach to the method of paired comparisons framework popularized by Kendall and Smith (1940). Then, we focus on the setting where all pairs of items, teams, players, or objects have been compared to …
