Methods for Meta–Analyses of Rare Events, Sparse Data, and Heterogeneity

The vast and complex wealth of information available to researchers often leads to a systematic review, which involves a detailed and comprehensive plan and search strategy with the goal of identifying, appraising, and synthesizing all relevant studies on a particular topic. A meta–analysis, conducted ideally as part of a comprehensive systematic review, statistically synthesizes evidence from multiple independent studies to produce one overall conclusion. The increasingly widespread use of meta–analysis has led to growing interest in meta–analytic methods for rare events and sparse data. Conventional approaches tend to perform very poorly in such settings. Recent work in this area has provided options for sparse data, but these are still often hampered when heterogeneity across the available studies differs based on treatment group. Heterogeneity arises when participants in a study are more correlated than participants across studies, often stemming from differences in the administration of the treatment, study design, or measurement of the outcome. We propose several new exact methods that accommodate this common contingency, providing more reliable statistical tests when such patterns on heterogeneity are observed. First, we develop a permutation–based approach that can also be used as a basis for computing exact confidence intervals when estimating the effect size. Second, we extend the permutation–based approach to the network meta–analysis setting. Third, we develop a new exact confidence distribution approach for effect size estimation. We show these new methods perform markedly better than traditional methods when events are rare, and heterogeneity is present

Combining Confidence Distributions for Rare Event Meta-Analyses in the Presence of Heterogeneity: Comparisons and Extensions

Confidence distributions have received increasing attention in recent years for statistical inference, specifically for meta-analyses involving rare events. Tian et al. [2009] proposed one application of confidence distributions for meta-analyses that involves combining confidence intervals, which have been shown to be a confidence distribution. Another approach by Liu et al. [2014] combines p-value functions, which are a type of confidence distribution. Additionally, an extension of Fisher\u27s p-value combination method is a confidence distribution. While several confidence distribution methods exist, no comparisons have been made to determine which method is best suited for meta-analyses with rare events or heterogeneity. This article compares the performance of these three confidence distribution approaches. We also propose and compare modifications of these three methods to better handle situations with rare events or heterogeneity

Effectiveness of Multilayer Graded-Z Forms of Radiation Shielding

This study explored how different forms of radiation shielding were more or less effective than standard single-layer shielding. Beta and gamma radiation sources were used and measured using a Geiger counter to determine how well the various forms of shielding protect against the radiation. The shielding effectiveness of standard homogeneous materials (e.g., graphite, carbon/epoxy composites, aluminum, and lead) of various thicknesses for different radiation sources was measured to provide standards for comparison. Once a basis of effective shielding was established, the study can go into greater depth into how to use shielding materials to be more effective, to better shield from secondary radiation (e.g., Bremsstrahlung x-rays), or allow controlled amounts of radiation to penetrate. Measurements investigated whether interleaved layering of different high-Z and low-Z shielding materials can be more effective or have different benefits than using a single material for shielding. Braided cabling and mesh materials were used to determine how much radiation, if any, still penetrated through such shielding configurations. The study provides a basis to understand the nature of multilayer graded-Z or braided cable coaxial radiation shielding proposed for the use in high radiation space environments

Effects of Communication Disorders on Children\u27s Development

This senior capstone research project examines the different forms of literature in regard to the effect of communicative disorders on children’s development. The paper discusses the implications of communication that influences a child’s development, such as personal development, social development, and academic success. It analyzes the different factors associated with communicative disorders, including the environmental and biological aspects. This capstone also emphasizes the importance and awareness of children’s communication disorders and further investigates how teachers and parents could provide support these children. The findings reveal that effective intermediation can help support and aid children in overcoming communication difficulties and avoid negative repercussions and enable children to overcome the developmental obstacles and help them to reach their full potential

Applications of Time-lapse Imagery for Monitoring and Illustrating Ecological Dynamics in a Water-stressed System

Understanding and perceiving the natural world is a key part of management, policy, conservation, and inevitably for our future. Increased demand on natural resources has heightened the importance of documenting ecosystem changes, and knowledge-sharing to foster awareness. The advancement of digital technologies has improved the efficiency of passive monitoring, connectivity among systems, and expanded the potential for innovative and communicative approaches. From technological progression, time-lapse imagery has emerged a valuable tool to capture and depict natural systems. I sought to enhance our understanding of a water-stressed system by analyzing imagery, in addition to integrating images with data visualization to illustrate the complexity of a river basin in central Nebraska. Image analysis was used to quantify wetland water inundation and vegetation phenology. These measurements from visible changes were combined with less visible data from additional passive monitoring to examine the relationship between vegetation phenology and bat activity, as well as wetland inundation and water quality. Moreover, time-lapse data sequences were constructed by integrating time-lapse imagery with data visualization in an interactive digital framework to examine the applications for communicating social-ecological dynamics. Findings suggest vegetation phenology was differentially associated with seasonal bat activity, possibly related to migratory versus resident life history strategies. In regards to examining wetland hydrology, water inundation was found to be correlated with nitrate, dissolved oxygen, and DEA, and negatively correlated with water temperature, indicating the importance of understanding water levels. AEM-RDA analysis identified several significant temporal patterns occurring with the wetland as well as the river site. Similarities between river and wetland patterns were suggestive of regional conditions driving fluctuations, while discrepancies were indicative of structural, biological, and local differences within individual sites. In examining communicative applications, time-lapse data sequences depicted a range of ecological dynamics while linking visible and invisible occurrences. The framework shows potential to offer a tangible context with explanatory content to aid in understanding environmental changes that are often too subtle to see or beyond the temporal scale of unaided human observation. Overall, cumulative findings suggest time-lapse imagery is of dual utility and has high potential for collecting data and illustrating ecological dynamics. Advisor: Craig R. Alle

The Last Rose of Summer

https://digitalcommons.library.umaine.edu/mmb-ps/3391/thumbnail.jp

Where the Warbling Waters Flow

Where the warbling waters flow, And the Zephyrs gently blow,Where the warbling waters flow,And the Zephyrs gently blow,The Fairies dwell, In grassy dell, Where the forest flowers grow-And the Zephyrs gently blow, And a joyous home is theirs,For it know not mortal cares.And its only tear, is the dew-drop clear;That the bending lily bears,And the only tear,Is the dew-drop clear;That the bending lily bears

A History and Economic Analysis of the Hyrum Reclamation Project

The Hyrum Project is located in northern Utah near the Cache County seat of Logan, and includes lands bordering the towns of Hyrum, Wellsville, and Mendon, Utah. The primary features of the project include a dam and reservoir on the Little Bear River, and three canals that total slightly more than 20 miles in length. Its principal purpose is to provide supplemental irrigation water to 6,800 acres of fertile land. This project is the result of several investigations relative to the improvement of water utilization in Cache County. A report prepared in 1922 entitled, Report on the Utilization of the Land and Water Resources of Cache Valley, Utah, stimulated interest and concern over the insufficient water supply. Beginning with this report, and until the final approval of the project in 1933, various county, state, and federal agencies worked together to devise a feasible method of increasing the supply of irrigation water in Cache Valley

Some experimental and theoretical aspects of structure and bonding as studied by ESCA

Not availabl