Pavelchak M.A.,Diagnostics Group
MATEC Web of Conferences | Year: 2015
Buildings are subjected to a myriad of vibration excitation sources including mechanical systems, human activity, vehicular traffic, and other environmental conditions. The characteristics (amplitude and frequency) of the excitation from these sources can vary significantly overtime as building use patterns change, systems age, and maintenance activities vary. Overtime many building owners/operators find themselves dealing with vibration complaints which arise unexpectedly and without obvious cause. The complexity of many modern facilities can make pinpointing the source of bothersome vibrations equivalent to finding a needle in a haystack. The objective of this paper is to explore the process of vibration source detection in complex existing facilities through three recent case studies. The vibration testing and evaluation methodologies utilized for source detection on these case studies is explored to highlight challenges faced on these types of projects. Each of the case studies involve existing buildings with many years of successful operation before bothersome vibration events were reported. The case studies presented, explore complaints related to sensitive medical equipment as well as human perception of vibrations. © 2015 Owned by the authors, published by EDP Sciences.
De Luca A.,Diagnostics Group |
Nardone F.,University of Naples Federico II |
Lignola G.P.,University of Naples Federico II |
Prota A.,University of Naples Federico II |
And 2 more authors.
Advances in Structural Engineering | Year: 2013
This paper discusses the laboratory testing of wall-like reinforced concrete (RC) columns externally confined with glass fiber reinforced polymer (GFRP) laminates and subjected to pure axial load. Specimens were characterized by an overall length of 3.05 m (10 ft), cross-sectional dimensions of 356 by 1,041 mm (14 by 41 in). Three specimens were tested: one was unstrengthened (benchmark) and two were confined with GFRP laminates. Two different confining reinforcement ratios were considered. The experimental investigation aimed at characterizing: the confinement contribution in terms of axial strength and prevention of instability of longitudinal bars, and the sensitivity of any enhancement in performance to the confining reinforcement ratio. The experimental axial stress - axial strain curves are also discussed.
Madej R.M.,Roche Holding AG |
Davis J.,Diagnostics Group |
Holden M.J.,U.S. National Institute of Standards and Technology |
Kwang S.,Bio Rad Laboratories Inc. |
And 2 more authors.
Journal of Molecular Diagnostics | Year: 2010
The utility of quantitative molecular diagnostics for patient management depends on the ability to relate patient results to prior results or to absolute values in clinical practice guidelines. To do this, those results need to be comparable across time and methods, either by producing the same value across methods and test versions or by using reliable and stable conversions. Universally available standards and reference materials specific to quantitative molecular technologies are critical to this process but are few in number. This review describes recent history in the establishment of international standards for nucleic acid test development, organizations involved in current efforts, and future issues and initiatives. Copyright © American Society for Investigative Pathology and the Association for Molecular Pathology.
Pabian S.,Diagnostics Group |
Thomas A.,Palmer Engineering |
Davis B.,University of Kentucky |
Murray T.M.,Virginia Polytechnic Institute and State University
Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress | Year: 2013
Floor vibration serviceability is a primary design consideration for steel framed floors and numerous evaluation methods have been proposed over the last 35 years or so. However, there is relatively little information available on the accuracy of the methods. Therefore, the objective of this study is to investigate the accuracy of the following five well-known methods: Modified Reiher-Meister, Murray Criterion, Hugo Bachmann's Method, AISC Design Guide 11 Chapter 4, and the SCI P354 Simplified Method. The methods listed above were used to evaluate the bays in an extensive 122 bay database to determine the accuracy of prediction of natural frequencies and overall acceptability. The SCI P354 most accurately predicted the natural frequency, with an average measured-to-predicted ratio of 1.01 (24% COV). The AISC Design Guide 11 most accurately predicted floor bay acceptability, with a 91% agreement with observations. © 2013 American Society of Civil Engineers.
Golden A.,Diagnostics Group |
Steel C.,National Institute of Allergy and Infectious Diseases |
Yokobe L.,Diagnostics Group |
Jackson E.,Diagnostics Group |
And 7 more authors.
PLoS ONE | Year: 2013
Onchocerciasis is a neglected tropical disease caused by infection with the parasite Onchocerca volvulus (Ov). An estimated 180 million people are at risk for Ov infection, and 37 million people are infected, mostly in Africa. A lateral flow-based assay to detect human IgG4 antibodies to the Ov-specific antigen Ov-16 was developed as a rapid tool to detect exposure to Ov. The test, when performed on 449 sera specimens from patients with microfiladermia and Ov-negative patients, has a sensitivity of 89.1% (95% confidence interval: 86.2%-92.0%), and specificity of 97% (95% confidence interval: 95.4%-98.6%). Because the intended use of the test is for surveillance, it is highly desirable to have a stable, long-lasting result. An extended read window is thus desirable for a high-volume, busy workflow and facilitates post-surveillance quality assurance. The main restriction on achieving an extended read window for this assay was the erythrocyte lysis that can alter the signal-to-noise ratio, especially in those with low IgG4 levels (weak positives). We describe a test housing that incorporates a user-independent feature driven by assay fluid and an expanding wick that detaches the blood separation membrane from the nitrocellulose used in the assay, but before hemolysis occurs. We demonstrated material functionality at extreme operational conditions (37°C, 80% relative humidity) and a read window of a minimum of 70 days. The fluid-driven assay device performs equally as well with whole blood as with plasma, as demonstrated with 100 spiked clinical specimens (with a correlation coefficient of 0.96). We show a novel, inexpensive, and simple approach to actuating the detachment of the blood separation membrane from the nitrocellulose test with no impact on the performance characteristics of the test.