47 research outputs found
A factor analytic study of the Italian National Institute of Health Quality of Life – Core Evaluation Form (ISSQoL-CEF)
Objectives: The Italian National Institute of Health Quality of Life - Core Evaluation Form (ISSQoL-CEF) is a specific questionnaire measuring health-related quality of life for human immunodeficiency virus-infected people in the era of highly active antiretroviral therapy. The main goal of this study was to examine the construct validity of this questionnaire by confirmation of its hypothesized dimensional structure. Methods: Baseline quality of life data from four clinical studies were collected and a confirmatory factor analysis of the ISSQoL-CEF items was carried out. Both first-order and secondorder factor models were tested: Model 1 with nine correlated first-order factors; Model 2 with three correlated second-order factors (Physical, Mental, and Social Health); Model 3 with two correlated second-order factors (Physical and Mental/Social Health); Model 4 with only one second-order factor (General Health). Results: A total of 261 patients were surveyed. Model 1 had a good fit to the data. Model 2 had an acceptable fit to the data and it was the best of all hierarchical models. However, Model 2 fitted the data worse than Model 1. Conclusions: The findings of in this study, consistent with the results of previous study, pointed out the construct validity of the ISSQoL-CEF. © 2010 Lauriola et al, publisher and licensee Dove Medical Press Ltd
Sub-wavelength surface IR imaging of soft-condensed matter
Outlined here is a technique for sub-wavelength infrared surface imaging
performed using a phase matched optical parametric oscillator laser and an
atomic force microscope as the detection mechanism. The technique uses a novel
surface excitation illumination approach to perform simultaneously chemical
mapping and AFM topography imaging with an image resolution of 200 nm. This
method was demonstrated by imaging polystyrene micro-structures
Seven Key Principles of Program and Project Success: A Best Practices Survey
The National Aeronautics and Space Administration (NASA) Organization Design Team (ODT), consisting of 20 seasoned program and project managers and systems engineers from a broad spectrum of the aerospace industry, academia, and government, was formed to support the Next Generation Launch Technology (NGLT) Program and the Constellation Systems Program. The purpose of the ODT was to investigate organizational factors that can lead to success or failure of complex government programs, and to identify tools and methods for the design, modeling, and analysis of new and more-efficient program and project organizations. The ODT conducted a series of workshops featuring invited lectures from seasoned program and project managers representing 25 significant technical programs spanning 50 years of experience. The result was the identification of seven key principles of program success that can be used to help design and operate future program organizations. This paper presents the success principles and examples of best practices that can significantly improve the design of program, project, and performing technical line organizations, the assessment of workforce needs and organization performance, and the execution of programs and projects
Probabilistic risk assessment of the Space Shuttle. Phase 3: A study of the potential of losing the vehicle during nominal operation. Volume 4: System models and data analysis
In this volume, volume 4 (of five volumes), the discussion is focussed on the system models and related data references and has the following subsections: space shuttle main engine, integrated solid rocket booster, orbiter auxiliary power units/hydraulics, and electrical power system
Probabilistic risk assessment of the Space Shuttle. Phase 3: A study of the potential of losing the vehicle during nominal operation. Volume 5: Auxiliary shuttle risk analyses
Volume 5 is Appendix C, Auxiliary Shuttle Risk Analyses, and contains the following reports: Probabilistic Risk Assessment of Space Shuttle Phase 1 - Space Shuttle Catastrophic Failure Frequency Final Report; Risk Analysis Applied to the Space Shuttle Main Engine - Demonstration Project for the Main Combustion Chamber Risk Assessment; An Investigation of the Risk Implications of Space Shuttle Solid Rocket Booster Chamber Pressure Excursions; Safety of the Thermal Protection System of the Space Shuttle Orbiter - Quantitative Analysis and Organizational Factors; Space Shuttle Main Propulsion Pressurization System Probabilistic Risk Assessment, Final Report; and Space Shuttle Probabilistic Risk Assessment Proof-of-Concept Study - Auxiliary Power Unit and Hydraulic Power Unit Analysis Report
Probabilistic risk assessment of the Space Shuttle. Phase 3: A study of the potential of losing the vehicle during nominal operation. Volume 2: Integrated loss of vehicle model
The application of the probabilistic risk assessment methodology to a Space Shuttle environment, particularly to the potential of losing the Shuttle during nominal operation is addressed. The different related concerns are identified and combined to determine overall program risks. A fault tree model is used to allocate system probabilities to the subsystem level. The loss of the vehicle due to failure to contain energetic gas and debris, to maintain proper propulsion and configuration is analyzed, along with the loss due to Orbiter, external tank failure, and landing failure or error
Probabilistic risk assessment of the Space Shuttle. Phase 3: A study of the potential of losing the vehicle during nominal operation, volume 1
This document is the Executive Summary of a technical report on a probabilistic risk assessment (PRA) of the Space Shuttle vehicle performed under the sponsorship of the Office of Space Flight of the US National Aeronautics and Space Administration. It briefly summarizes the methodology and results of the Shuttle PRA. The primary objective of this project was to support management and engineering decision-making with respect to the Shuttle program by producing (1) a quantitative probabilistic risk model of the Space Shuttle during flight, (2) a quantitative assessment of in-flight safety risk, (3) an identification and prioritization of the design and operations that principally contribute to in-flight safety risk, and (4) a mechanism for risk-based evaluation proposed modifications to the Shuttle System. Secondary objectives were to provide a vehicle for introducing and transferring PRA technology to the NASA community, and to demonstrate the value of PRA by applying it beneficially to a real program of great international importance