Initiation of atrial fibrillation by interaction of pacemakers with geometrical constraints.

Atrial fibrillation (AF) is the most common arrhythmia of the heart in industrialized countries. Its generation and the transitory behavior of paroxysmal AF are still not well understood. In this work we examine the interaction of two activation sources via an isthmus as possible cause for the initiation of fibrillation episodes.

Multifaceted syndromic surveillance in a public health department using the early aberration reporting system.

Local health departments concerned with early detection of potential terrorist threats are beginning to explore novel approaches to syndromic surveillance. Using the Early Aberration Reporting System (EARS) developed by the Centers for Disease Control and Prevention, a metropolitan health department in Tennessee and five community partners have agreed to exchange data in order to implement a multifaceted syndromic surveillance system for early detection of a biological attack. This article describes how we used EARS as the foundation for implementing a surveillance system that encompasses a rich variety of data sources.

Comparing aberration detection methods with simulated data.

We compared aberration detection methods requiring historical data to those that require little background by using simulated data. Methods that require less historical data are as sensitive and specific as those that require 3-5 years of data. These simulations can determine which method produces appropriate sensitivity and specificity.

A simulation model for assessing aberration detection methods used in public health surveillance for systems with limited baselines.

Public health officials continue to develop and implement new types of ongoing surveillance systems in an attempt to detect aberrations in surveillance data as early as possible. In public health surveillance, aberrations are traditionally defined as an observed value being greater than an expected historical value for that same time period. To account for seasonality, traditional aberration detection methods use three or more years of baseline data across the same time period to calculate the expected historical value.

The bioterrorism preparedness and response Early Aberration Reporting System (EARS).

Data from public health surveillance systems can provide meaningful measures of population risks for disease, disability, and death. Analysis and evaluation of these surveillance data help public health practitioners react to important health events in a timely manner both locally and nationally. Aberration detection methods allow the rapid assessment of changes in frequencies and rates of different health outcomes and the characterization of unusual trends or clusters.