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Cai L.,University of Pittsburgh | Rizzo P.,University of Pittsburgh | Al-Nazer L.,Office of Research and Development
International Journal of Solids and Structures | Year: 2013

This paper describes the coupling mechanism between highly nonlinear solitary waves propagating along a granular system and slender beams in contact with the granular medium. Nonlinear solitary waves are compact non-dispersive waves that can form and travel in nonlinear systems such as one-dimensional chains of particles, where they are conventionally generated by the mechanical impact of a striker. These waves have a constant spatial wavelength and their speed, amplitude, and duration can be tuned by modifying the particles' material or size, or the velocity of the striker. In the study presented in this article we investigated numerically the interaction between solitary waves propagating along a chain of granular particles and a slender beam. Some of the numerical findings were validated experimentally. We found that the geometric and mechanical properties of the beam or thermal stress applied to the beam alter certain features of the solitary waves. In the future, these findings may be used to develop a novel sensing system for the nondestructive assessment of beams. © 2013 Elsevier Ltd. All rights reserved. Source

Chang N.-B.,University of Central Florida | Xuan Z.,University of Central Florida | Yang Y.J.,Office of Research and Development
Remote Sensing of Environment | Year: 2013

This paper explores the spatiotemporal patterns of total phosphorus (TP) in Tampa Bay (Bay), Florida, with the aid of Moderate Resolution Imaging Spectroradiometer (MODIS) images and genetic programming (GP) models. The study was designed to link TP concentrations with relevant water quality parameters and remote sensing reflectance bands in aquatic environments using in-situ data from a local database to support the calibration and validation of the GP model. The GP models show the effective capacity to demonstrate snapshots of spatiotemporal distributions of TP across the Bay, which helps to delineate the short-term seasonality effects and the decadal trends of TP in an environmentally sensitive coastal bay area. In the past decade, urban development and agricultural activities in the Bay area have substantially increased the use of fertilizers. Landfall hurricanes, including Frances and Jeanne in 2004 and Wilma in 2005, followed by continuous droughts from 2006 to 2008 in South Florida, made the Bay area an ideal place for a remote sensing impact assessment. A changing hydrological cycle, triggered by climate variations, exhibited unique regional patterns of varying TP waste loads into the Bay over different time scales ranging from seasons to years. With the aid of the derived GP model in this study, we were able to explore these multiple spatiotemporal distributions of TP concentrations in the Tampa Bay area aquatic environment and to elucidate these coupled dynamic impacts induced by both natural hazards and anthropogenic perturbations. This advancement enables us to identify the hot moments and hot spots of TP concentrations in the Tampa Bay region. © 2013 Elsevier Inc.. Source

Atkins D.,Quality Enhancement Research Initiative | Kupersmith J.,Office of Research and Development | Eisen S.,Health Services Research and Development
Health Affairs | Year: 2010

Comparative effectiveness research is a tool to use in achieving patient-centered, high-value health care. However, applying the results to individual patients and health systems raises unique issues. Here, we review lessons learned by the Veterans Health Administration (VHA) in developing and implementing the research in a large integrated health system. Decision makers should examine whether individual studies apply to diverse populations, align tools and incentives to adopt evidence-based practices, and consider both the patient and population perspectives. A key challenge remains how to incorporate comparative evidence and patient values into busy clinical practices. © 2010 Project HOPE-The People-to-People Health Foundation, Inc. Source

Karn B.,Office of Research and Development
Journal of Environmental Monitoring | Year: 2011

Rare earth elements and several metals formerly uncommon in commerce are being introduced into new products, particularly as nanoscaled materials. Until recently, little attention has been paid to their sustainability issues. This perspective addresses these elements, their commercial uses, health and environment issues, sustainability, and suggests a path forward. © 2011 The Royal Society of Chemistry. Source

Steelman V.M.,Office of Research and Development | Steelman V.M.,Center for Research in the Implementation of Innovative Strategies in Practice
American Journal of Surgery | Year: 2011

Background: A retained surgical sponge is a serious medical error that results in negative patient outcomes. Radiofrequency (RF) technology has recently been introduced to evaluate for the presence of a retained sponge. The aim of this study was to evaluate the sensitivity and specificity of the detection of surgical sponges embedded with an RF chip through the torsos of subjects of varying body habitus, including the morbidly obese. Methods: A prospective, crossover, and observer blinded study design was used. Subjects served as their own controls. With the subject supine, 4 surgical sponges were sequentially placed behind the subject's torso in locations approximating abdominal quadrants. Results: Two hundred ten subjects were enrolled in the study. Nearly half (n = 101) were morbidly obese. Eight hundred forty readings were taken. There were no false-positive or false-negative readings. The sensitivity and specificity of detection of the RF sponges through the torsos of subjects of varying body habitus were 100%. Conclusions: The sensitivity and specificity of RF sponge technology are much higher than published reports of surgical counts or published findings of intraoperative radiographs for retained sponges. Copyright © 2011 Published by Elsevier Inc. Source

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