Point-of-care breath test for biomarkers of active pulmonary tuberculosis

Rationale: Volatile organic compounds (VOCs) in breath provide biomarkers of tuberculosis (TB) because Mycobacterium tuberculosis manufactures VOC metabolites that are detectable in the breath of infected patients. Objectives: We evaluated breath VOC biomarkers in subjects with active pulmonary TB, using an internet-linked rapid point-of-care breath test. Methods: 279 subjects were studied at four centers in three countries, Philippines, UK, and India, and data was analyzed from 251 (130 active pulmonary TB, 121 controls). A point-of-care system collected and concentrated breath and air VOCs, and analyzed them with automated thermal desorption, gas chromatography, and surface acoustic wave detection. A breath test was completed in 6 min. Chromatograms were converted to a series of Kovats Index (KI) windows, and biomarkers of active pulmonary TB were identified by Monte Carlo analysis of KI window alveolar gradients (abundance in breath minus abundance in room air). Measurements and main results: Multiple Monte Carlo simulations identified eight KI windows as biomarkers with better than random performance. Four KI windows corresponded with KI values of VOCs previously identified as biomarkers of pulmonary TB and metabolic products of M. tuberculosis, principally derivatives of naphthalene, benzene and alkanes. A multivariate predictive algorithm identified active pulmonary TB with 80% accuracy (area under curve of receiver operating characteristic curve), sensitivity = 71.2%, and specificity = 72%. Accuracy increased to 84% in age-matched subgroups. In a population with 5% prevalence, the breath test would identify active pulmonary TB with 98% negative predictive value and 13% positive predictive value. Conclusions: A six-minute point-of-care breath test for volatile biomarkers accurately identified subjects with active pulmonary TB. © 2011 Elsevier Ltd. All rights reserved

Real-Time Visualization of Aerospace . . .

In this thesis, a new, general-purpose software system for computational steering has been developed to carry out simulations on parallel computers and visualize them remotely in real-time. The steering system is extremely lightweight, portable, robust and easy to use. As a demonstration of the capabilities of this system, two applications have been developed. A parallel wake-vortex simulation code has been written and integrated with a Virtual Reality (VR) system via a separate graphics client. The coupling of computational steering of paral-lel wake-vortex simulation with VR setup provides us with near real-time visualization of the wake-vortex data in stereoscopic mode. It opens a new way for the future Air-Traffic Control systems to help reduce the capacity constraint and safety problems resulting from the wake-vortex hazard that are plaguing the airports today. In another application, an existing compu-tational fluid dynamics code has been integrated with the steering system to enable interactive visualization of complex flow simulations from any remote workstation. Benefits of scalability and dimensional reduction arising from this approach have been imperative in the development of this system. This system makes the visualization of flow simulations easier, efficient, an

Real time visualization of wake vortex simulations using computational steering and beowulf clusters

In this paper, we present the design and implementation of POSSE, a new, lightweight computational steering system based on a client/server programming model. We demonstrate the effectiveness of this software system by illustrating its use for a visualization client designed for a particularly demanding real-time application--wake-vortex simulations for multiple aircraft running on a parallel Beowulf cluster. We describe how POSSE is implemented as an object-oriented, class-based software library and illustrate its ease of use from the perspective of both the server and client codes. We discuss how POSSE handles the issue of data coherency of distributed data structures, data transfer between different hardware representations, and a number of other implementation issues. Finally, we consider how this approach could be used to augment AVOSS (an air traffic control system currently being developed by the FAA) to significantly increase airport utilization while reducing the risks of accidents. Document type: Part of book or chapter of boo

Real-Time Visualization of Wake-Vortex Simulations using Computational Steering and Beowulf Clusters

Abstract. In this paper, we present the design and implementation of POSSE, a new, lightweight computational steering system based on a client/server programming model. We demonstrate the effectiveness of this software system by illustrating its use for a visualization client designed for a particularly demanding real-time application—wake-vortex simulations for multiple aircraft running on a parallel Beowulf cluster. We describe how POSSE is implemented as an object-oriented, class-based software library and illustrate its ease of use from the perspective of both the server and client codes. We discuss how POSSE handles the issue of data coherency of distributed data structures, data transfer between different hardware representations, and a number of other implementation issues. Finally, we consider how this approach could be used to augment AVOSS (an air traffic control system currently being developed by the FAA) to significantly increase airport utilization while reducing the risks of accidents.

Scalable Computational Steering System for Visualization Of Large-Scale CFD Simulations

A general-purpose computational steering system (POSSE) which can be coupled to any C/C++ simulation code, has been developed and tested with a 3-D Navier-Stokes flow solver (PUMA2). This paper illustrates how to use "computational steering" with PUMA2 to visualize CFD solutions while they are being computed, and even change the input data while it is running. In addition, the visualizations can be displayed using virtual reality facilities (such as CAVEs and RAVEs) to better understand the 3-D nature of the flowfields. The simulations can be run on parallel computers or Beowulf clusters, while the visualization is performed on other computers, through a clientserver approach. A key advantage of our system is its scalability. The visualization is performed using a parallel approach. This is essential for large-scale simulations, since it is often not possible to postprocess the entire flowfield on a single computer due to memory and speed constraints. Example solutions from this solver are presented to show the usefulness of POSSE. The examples include unsteady ship airwake simulations, unsteady flow over a helicopter fuselage, and unsteady simulations of a helicopter rotor. The results of the rotor simulations in hover are compared with the experimental measurement and discussed in some detail. The advantages of using object-oriented programming are also discussed