Statistics and Probability Commons^™

Profiles Of Drug Endangered Children: Investigation In A Clinical Sample, Imanie Samanmali Wijayaratne

Loma Linda University Electronic Theses, Dissertations & Projects

Despite the increase in children born prenatally exposed to methamphetamine, little is known about the cognitive and neuropsychological outcomes of these children. Research specific to prenatal-methamphetamine exposure is extremely limited and has been primarily restricted to rat studies. This research combined with the few studies examining children prenatally exposed to methamphetamine suggests that methamphetamine-exposure is associated with various cognitive and neuropsychological delays and is impacted by both biological and environmental factors. Given the scarcity of research in this area, the current study used archival data from a psychological assessment clinic to (1) describe the frequency of prenatal methamphetamine-exposure cases, (2) …

Observer Reliability Of Cephalometric Landmark Identification On 3-D Mr Images, Michael S. Pollack

Loma Linda University Electronic Theses, Dissertations & Projects

Introduction: Cephalometric analysis is a cornerstone of orthodontic diagnosis, yet much information is lost when 3-dimensional structures are assessed with 2-dimensional methods. CBCT offers 3-dimensional imaging but at the cost of higher levels of ionizing radiation. Magnetic resonance imaging provides 3-dimensional imaging without ionizing radiation and additionally imparts visualization of soft tissue structures. Prior to employing MR images for cephalometric analysis, reliability of landmark identification must be assessed. The purpose of this study was to evaluate intra- and interobserver reliability in 3-dimensional landmark identification using MR images.

Materials and Methods: Fifteen cranial MR images (3.0 T, MP-RAGE) from subjects between …

Comparing Risk Scoring Systems Beyond The Roc Paradigm In Survival Analysis, Hajime Uno, Lu Tian, Tianxi Cai, Isaac S. Kohane, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

The Effects Of Physical Activity And Nutrient Intake On The Risk Of Hip Fracture : Results From The Adventist Health Study-2, Wen-Ling Liao

Loma Linda University Electronic Theses, Dissertations & Projects

This is a two year of follow up study of Adventist Health Study-2 (AHS-2). We assessed the association between physical activity, nutrient intake and risk of hip fracture among peri- and post menopausal Caucasian women using unconditional logistic regression models. All subjects completed a lifestyle questionnaire which including information of physical activity and frequency and portion size of food intake at enrollment into the study (2002-2007). The “Bi-Annual Hospitalization History” questionnaire which included a question about hip fractures due to minor trauma/falls was sent to subjects approximately two years after enrollment, with a response rat of 82.84%. In this cohort, …

A Spatio-Temporal Approach For Estimating Chronic Effects Of Air Pollution, Sonja Greven, Francesca Dominici, Scott L. Zeger

Johns Hopkins University, Dept. of Biostatistics Working Papers

Estimating the health risks associated with air pollution exposure is of great importance in public health. In air pollution epidemiology, two study designs have been used mainly. Time series studies estimate acute risk associated with short-term exposure. They compare day-to-day variation of pollution concentrations and mortality rates, and have been criticized for potential confounding by time-varying covariates. Cohort studies estimate chronic effects associated with long-term exposure. They compare long-term average pollution concentrations and time-to-death across cities, and have been criticized for potential confounding by individual risk factors or city-level characteristics.

We propose a new study design and a statistical model, …

Spatial Cluster Detection For Repeatedly Measured Outcomes While Accounting For Residential History, Andrea J. Cook, Diane Gold, Yi Li

Harvard University Biostatistics Working Paper Series

No abstract provided.

Spatial Cluster Detection For Weighted Outcomes Using Cumulative Geographic Residuals, Andrea J. Cook, Yi Li, David Arterburn, Ram C. Tiwari

Harvard University Biostatistics Working Paper Series

No abstract provided.

A Machine-Learning Algorithm For Estimating And Ranking The Impact Of Environmental Risk Factors In Exploratory Epidemiological Studies, Jessica G. Young, Alan E. Hubbard, B Eskenazi, Nicholas P. Jewell

U.C. Berkeley Division of Biostatistics Working Paper Series

No abstract provided.

The Effects Of A Psychoneuroimmunology Based Lifestyle Intervention In Modifying The Progression Of Major Depression In Clinically Depressed Adults, Ruth A. Tanyi

Loma Linda University Electronic Theses, Dissertations & Projects

Chronic stress can lead to poorly controlled upsurges of cortisol and dysregulation of the hypothalamic pituitary-adrenal axis, thereby contributing to major depression. Hence, researchers have begun to examine the effects of individual psychoneuroimmunology (PNI) interventions and their impact on modifying stress and depression. However, there is a lack of studies that have examined the composite effect(s) of a PNI-based lifestyle intervention and major depression. Thus, this randomized interventional study examined the composite effect(s) of a PNI-based lifestyle intervention: combined progressive muscle relaxation and spiritual guided imagery and humor as an adjunct therapy to modifying the progression of depression. Participants were …

Anthropometric Parameters Of Under-Five Years Old Children With Different Dietary Habits In Ukambani Region : A Study In Eastern Rural Kenya, Hellen M. Ndiku

Loma Linda University Electronic Theses, Dissertations & Projects

The objective of this descriptive cross sectional study was to assess dietary intake and nutritional status of children under-five years in two rural sites of Eastern Kenya where the staple cereals may differ. A modified rapid, knowledge, practice and coverage (KPC) questionnaire and a 24-hr dietary recall form were used to collect the data. A total of 403 households were surveyed from four randomly selected divisions. This yielded 629 surrogate 24-hr dietary recalls of children < 5 years with 314 from Mwingi district and 315 from Makueni district (49 % boys and 51 % girls).

Statistical analysis was done using SPSS and SAS. Comparison of means was done using t- test and chi square was used for proportions. The 24-hr …

The Importance Of Scale For Spatial-Confounding Bias And Precision Of Spatial Regression Estimators, Christopher J. Paciorek

Harvard University Biostatistics Working Paper Series

Increasingly, regression models are used when residuals are spatially correlated. Prominent examples include studies in environmental epidemiology to understand the chronic health effects of pollutants. I consider the effects of residual spatial structure on the bias and precision of regression coefficients, developing a simple framework in which to understand the key issues and derive informative analytic results. When the spatial residual is induced by an unmeasured confounder, regression models with spatial random effects and closely-related models such as kriging and penalized splines are biased, even when the residual variance components are known. Analytic and simulation results show how the bias …

Smoking Enhances Risk For New External Genital Warts In Men, Dorothy J. Wiley, David Elashoff, Emmanuel V. Masongsong, Diane M. Harper

Dartmouth Scholarship

Repeat episodes of HPV-related external genital warts reflect recurring or new infections. No study before has been sufficiently powered to delineate how tobacco use, prior history of EGWs and HIV infection affect the risk for new EGWs. Behavioral, laboratory and examination data for 2,835 Multicenter AIDS Cohort Study participants examined at 21,519 semi-annual visits were evaluated. Fourteen percent (391/2835) of men reported or were diagnosed with EGWs at 3% (675/21,519) of study visits. Multivariate analyses showed smoking, prior episodes of EGWs, HIV infection and CD4+ T-lymphocyte count among the infected, each differentially influenced the risk for new EGWs.

Analysis Of Randomized Comparative Clinical Trial Data For Personalized Treatment Selections, Tianxi Cai, Lu Tian, Peggy H. Wong, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Group Comparison Of Eigenvalues And Eigenvectors Of Diffusion Tensors, Armin Schwartzman, Robert F. Dougherty, Jonathan E. Taylor

Harvard University Biostatistics Working Paper Series

No abstract provided.

Immediate Loading Of Unsplinted Implants In The Anterior Mandible For Overdentures, Phillip Roe

Loma Linda University Electronic Theses, Dissertations & Projects

In this one-year prospective study, eight completely edentulous patients were selected from the Loma Linda University School of Dentistry (LLUSD) patient population to participate. There were five male and three female patients, between the ages of 58 and 82 (mean age of 69.1 years). All participants received new maxillary and mandibular complete dentures prior to implant placement. Two 4.0 mm x 13 mm threaded implants with a fluoride-modified, micro-roughened, titanium surface were placed mesial to each mandibular canine position. Locator abutments were connected and torqued to 25 Ncm and primary closure was achieved with a nonresorbable suture material. The Locator …

The Prevalence And Determinants Of Health Risk Behaviors Among High School Students In Mexico, Nellie León

Loma Linda University Electronic Theses, Dissertations & Projects

The Centers for Disease Control and Prevention report that despite health promotion efforts, adolescents continue to engage in behaviors that put them at risk for morbidity and mortality. Alcohol consumption, illicit drug use, smoking, and risky sexual behaviors are among the behaviors that contribute to leading causes of morbidity and mortality in youth; these four behaviors were explored in this study. An observational cross-sectional design was utilized. The Youth Risk Behavior Survey from the Centers for Disease Control and Prevention was utilized to assess the prevalence of the four risk behaviors among high school students in Jalisco, Mexico. Items constructed …

Understanding The Physical Properties That Control Protein Crystallization By Analysis Of Largescale Experimental Data, W. Nicholson Price Ii, Yang Chen, Samuel K. Handelman, Helen Neely, Philip Manor, Richard Karlin, Rajesh Nair, Jinfeng Liu, Michael Baran, John Everett, Saichiu N. Tong, Farhad Forouhar, Swarup S. Swaminathan, Thomas Acton, Rong Xiao, Joseph R. Luft, Angela Lauricella, George T. Detitta, Burkhard Rost, Gaetano T. Montelione, John T. Hunt

Law Faculty Scholarship

Crystallization is the most serious bottleneck in high-throughput protein-structure determination by diffraction methods. We have used data mining of the large-scale experimental results of the Northeast Structural Genomics Consortium and experimental folding studies to characterize the biophysical properties that control protein crystallization. This analysis leads to the conclusion that crystallization propensity depends primarily on the prevalence of well-ordered surface epitopes capable of mediating interprotein interactions and is not strongly influenced by overall thermodynamic stability. We identify specific sequence features that correlate with crystallization propensity and that can be used to estimate the crystallization probability of a given construct. Analyses of …

Barriers Encountered During Enrollment In An Internet-Mediated Randomized Controlled Trial, Lorraine R. Buis, Adrienne W. Janney, Michael L. Hess, Silas A. Culver, Caroline R. Richardson

Wayne State University Associated BioMed Central Scholarship

Abstract

Background

Online technology is a promising resource for conducting clinical research. While the internet may improve a study's reach, as well as the efficiency of data collection, it may also introduce a number of challenges for participants and investigators. The objective of this research was to determine the challenges that potential participants faced during the enrollment phase of a randomized controlled intervention trial of Stepping Up to Health, an internet-mediated walking program that utilized a multi-step online enrollment process.

Methods

We conducted a quantitative content analysis of 623 help tickets logged in a participant management database during the enrollment …

The Influence Of Familism On Descriptive And Injunctive Norms In Predicting The Intention To Eat A Vegetarian Diet Among Chinese Seventh-Day Adventists, See Wei Toh

Loma Linda University Electronic Theses, Dissertations & Projects

According to the theory of planned behavior (TpB), one determinant of intention to engage in a behavior is the subjective norm. Various studies have found that subjective norm is often the weaker predictor of intention compared to perceived behavioral control and attitude. This study examined whether familism (emphasis on the family rather than the individual) would contribute positively to the predictive power of the TpB model through interactions with the family portion of descriptive and injunctive norms. Descriptive and injunctive norms are component variables of the subjective norm. A sample of 284 adult Chinese Seventh-day Adventists 18 years and older …

Complete Identification Of Permissible Sampling Rates For First-Order Sampling Of Multi-Band Bandpass Signals, Yan Wu, Daniel F. Linder

Biostatistics: Faculty Publications

The first-order sampling of multi-band bandpass signals with arbitrary band positions is considered in this paper. Gaps between the spectral sub-bands are utilized to achieve lower sampling rates than the Nyquist. The lowest possible sampling rate along with other permissible sampling rates is identified via a unique partition of the frequency axis. With the complete identification of all the permissible sampling rates, a necessary and sufficient sampling theorem for multi-band bandpass signals is presented in terms of a series of csinc-interpolators.

A Small Sample Correction For Estimating Attributable Risk In Case-Control Studies, Daniel B. Rubin

U.C. Berkeley Division of Biostatistics Working Paper Series

The attributable risk, often called the population attributable risk, is in many epidemiological contexts a more relevant measure of exposure-disease association than the excess risk, relative risk, or odds ratio. When estimating attributable risk with case-control data and a rare disease, we present a simple correction to the standard approach making it essentially unbiased, and also less noisy. As with analogous corrections given in Jewell (1986) for other measures of association, the adjustment often won't make a substantial difference unless the sample size is very small or point estimates are desired within fine strata, but we discuss the possible utility …

Spatial Misalignment In Time Series Studies Of Air Pollution And Health Data, Roger D. Peng, Michelle L. Bell

Johns Hopkins University, Dept. of Biostatistics Working Papers

Time series studies of environmental exposures often involve comparing daily changes in a toxicant measured at a point in space with daily changes in an aggregate measure of health. Spatial misalignment of the exposure and response variables can bias the estimation of health risk and the magnitude of this bias depends on the spatial variation of the exposure of interest. In air pollution epidemiology, there is an increasing focus on estimating the health effects of the chemical components of particulate matter. One issue that is raised by this new focus is the spatial misalignment error introduced by the lack of …

Focus On Rna Isolation: Obtaining Rna For Microrna (Mirna) Expression Profiling Analyses Of Neural Tissue, Wang-Xia Wang, Bernard R. Wilfred, Donald A. Baldwin, R. Benjamin Isett, Na Ren, Arnold J. Stromberg, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are present in all known plant and animal tissues and appear to be somewhat concentrated in the mammalian nervous system. Many different miRNA expression profiling platforms have been described. However, relatively little research has been published to establish the importance of 'upstream' variables in RNA isolation for neural miRNA expression profiling. We tested whether apparent changes in miRNA expression profiles may be associated with tissue processing, RNA isolation techniques, or different cell types in the sample. RNA isolation was performed on a single brain sample using eight different RNA isolation methods, and results were correlated using a conventional …

Calibrating Parametric Subject-Specific Risk Estimation, Tianxi Cai, Lu Tian, Hajime Uno, Scott D. Solomon, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Evaluating Subject-Level Incremental Values Of New Markers For Risk Classification Rule, Tianxi Cai, Lu Tian, Donald M. Lloyd-Jones, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Cephalometric Analysis Using Magnetic Resonance Imaging, Wade A. Williams

Loma Linda University Electronic Theses, Dissertations & Projects

Purpose: The purpose of this study was to determine if T1-weighted 3D magnetic resonance images performed at 3.0 Tesla could be used to conduct routine orthodontic cephalometric analysis.

Methods: Three cranial imaging methods were compared using sixteen non-growing subjects (10 male and 6 female) who were not claustrophobic, did not have any metallic restorations on the distal of first molars, had no medical implants and the female subjects were not pregnant. Sagittal cranial images were produced by three methods: (1) a digital lateral cephalometric (LC) radiograph (Orthophos XG Plus, Sirona^TM, Bensheim, Germany), (2) a 12-inch FOV cone beam …

Orthodontic Mini-Implant Failure: Assessing The Relationship To Bone Quality Using Qcbct, Joshua Schneider

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to evaluate the cortical bone thickness (mm), cortical bone density (HU), and trabecular bone density (HU) of mini-implants sites in both the maxilla and mandible using QCBCT to determine if they had any effect on mini-implant failure rate. Patient characteristics (age, gender, facial type), mini-implant characteristics (date of placement, manufacturer, length, and diameter), and the mini-implant site (region) were also evaluated. One hundred and six mini-implants in 50 consecutive patients with complete patient records, CBCT information, and T1 radiographs were included in the study. Thirty-four of the 106 mini-implants were considered "failures" resulting in …

The Comparative Radiopacity Between Primary And Permanent Teeth, Robert C. Lee

Loma Linda University Electronic Theses, Dissertations & Projects

Purpose: This in vitro study compared the radiopacity between human primary and permanent enamel and dentin. It also compared the radiopacity between human anterior and posterior teeth.

Methods: Extracted primary and permanent teeth were used in this study. One mm enamel and one mm dentin slices were cut from each extracted tooth. Radiographs were taken of each enamel and dentin specimen 1 mm in thickness along with an aluminum step-wedge using procedures specified in International Standards Organization (ISO) 4049:2000. A densitometer was used to measure the Optical Density (OD) of the radiographs of the specimen and the accompanying aluminum step-wedge. …

Volunteer Studies In Pain Research — Opportunities And Challenges To Replace Animal Experiments: The Report And Recommendations Of A Focus On Alternatives Workshop, C. K. Langley, Q. Aziz, C. Bountra, N. Gordon, P. Hawkins, A. Jones, G. Langley, T. Nurmikko, I. Tracey

Experimentation Collection

Despite considerable research, effective and safe treatments for human pain disorders remain elusive. Understanding the biology of different human pain conditions and researching effective treatments continue to be dominated by animal models, some of which are of limited value. British and European legislation demands that non-animal approaches should be considered before embarking on research using experimental animals. Recent scientific and technical developments, particularly in human neuroimaging, offer the potential to replace some animal procedures in the study of human pain. A group of pain research experts from academia and industry met with the aim of exploring creatively the tools, strategies …

Joint Spatial Modeling Of Recurrent Infection And Growth With Processes Under Intermittent Observation, Farouk S. Nathoo

COBRA Preprint Series

In this article we present new statistical methodology for longitudinal studies in forestry where trees are subject to recurrent infection and the hazard of infection depends on tree growth over time. Understanding the nature of this dependence has important implications for reforestation and breeding programs. Challenges arise for statistical analysis in this setting with sampling schemes leading to panel data, exhibiting dynamic spatial variability, and incomplete covariate histories for hazard regression. In addition, data are collected at a large number of locations which poses computational difficulties for spatiotemporal modeling. A joint model for infection and growth is developed; wherein, a …