Characterizing Evaporation Ducts Within the Marine Atmospheric Boundary Layer Using Artificial Neural Networks

We apply a multilayer perceptron machine learning (ML) regression approach to infer electromagnetic (EM) duct heights within the marine atmospheric boundary layer (MABL) using sparsely sampled EM propagation data obtained within a bistatic context. This paper explains the rationale behind the selection of the ML network architecture, along with other model hyperparameters, in an effort to demystify the process of arriving at a useful ML model. The resulting speed of our ML predictions of EM duct heights, using sparse data measurements within MABL, indicates the suitability of the proposed method for real-time applications.Comment: 13 pages, 7 figure

Gaussian Process Regression for Estimating EM Ducting Within the Marine Atmospheric Boundary Layer

We show that Gaussian process regression (GPR) can be used to infer the electromagnetic (EM) duct height within the marine atmospheric boundary layer (MABL) from sparsely sampled propagation factors within the context of bistatic radars. We use GPR to calculate the posterior predictive distribution on the labels (i.e. duct height) from both noise-free and noise-contaminated array of propagation factors. For duct height inference from noise-contaminated propagation factors, we compare a naive approach, utilizing one random sample from the input distribution (i.e. disregarding the input noise), with an inverse-variance weighted approach, utilizing a few random samples to estimate the true predictive distribution. The resulting posterior predictive distributions from these two approaches are compared to a "ground truth" distribution, which is approximated using a large number of Monte-Carlo samples. The ability of GPR to yield accurate and fast duct height predictions using a few training examples indicates the suitability of the proposed method for real-time applications.Comment: 15 pages, 6 figure

Ready or Not? Protecting the Public's Health in the Age of Bioterrorism, 2004

Examines ten key indicators to evaluate state preparedness to respond to bioterrorist attacks and other public health emergencies. Evaluates the federal government's role and performance, and offers recommendations for improving readiness

F as in Fat: How Obesity Policies Are Failing in America, 2004

Examines national and state obesity rates and government policies. Focuses on setting a baseline of current policies and programs, and offers a comprehensive look at their range and quality

F as in Fat: How Obesity Policies Are Failing in America, 2005

Examines national and state obesity rates and government policies. Challenges the research community to focus on major research questions to inform policy decisions, and policymakers to pursue actions to combat the obesity crisis

Union representation, collective voice and job quality: an analysis of a survey of union members in the UK finance sector

This article seeks to identify whether employee perceptions of job quality are better in instances where an onsite union representative is present. It also seeks to identify whether the relationship between onsite representative presence and job quality is explained by employee perceptions of union collective voice. The analysis, based on a survey of union members in the UK finance sector, demonstrates that employee perceptions of several dimensions of job quality are better where an onsite representative is present, and that this can be explained by the higher perceptions of union collective voice that onsite representatives engender