541 research outputs found

    Systems Engineering and Integration (SE and I)

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    The issue of technology advancement and future space transportation vehicles is addressed. The challenge is to develop systems which can be evolved and improved in small incremental steps where each increment reduces present cost, improves, reliability, or does neither but sets the stage for a second incremental upgrade that does. Future requirements are interface standards for commercial off the shelf products to aid in the development of integrated facilities; enhanced automated code generation system slightly coupled to specification and design documentation; modeling tools that support data flow analysis; and shared project data bases consisting of technical characteristics cast information, measurement parameters, and reusable software programs. Topics addressed include: advanced avionics development strategy; risk analysis and management; tool quality management; low cost avionics; cost estimation and benefits; computer aided software engineering; computer systems and software safety; system testability; and advanced avionics laboratories - and rapid prototyping. This presentation is represented by viewgraphs only

    Levels of some heavy Metals in Cocoyam (Colocasia esculentum) grown on Soil receiving Effluent from a Paint Industry

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    The levels of some heavy metals in soil samples and tubers of cocoyam (Colocasia esculentum) grown on  soil receiving paint wastes (PWS) has been investigated using Atomic Absorption spectrophotometer  (Unicam 939/959 model). Similar analyses were carried out for the same plant from a control area. The  studies revealed that although the P.W.S contained abnormally high levels of Pb (474.14mgkg-1) and Cu  (137.85mgkg-1). The paint waste tuber (PWT) recorded low levels of these metals: Pb (2.13mgkg-1) and  Cu (13.85mgkg-1) respectively. Correlation analysis tested at 0.05 level of significance show that no significant correlation existed between the metals levels in the soil and the level in the tuber. In all cases the levels of the metals in the tubers were well below the upper limit documented for unpolluted plant. The results however suggest the ineffectiveness of the use of Colocasia esculentum as a bioindicator for heavy metal pollution in soil. © JASE

    A Change of Climate

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    A collection of poems about climate change, written by poets from across the globe and offering their local perspective on a global issue. This collection represents the top 20 poems that were selected as part of a global competition to find poems about climate change. Some of the poems in this collection are sad, some of them are angry, some of them are even funny. But all of them are real. Real poems from real people about the very real topic of climate change. All profits from this book will be used to support the Environmental Justice Foundation, who investigate and expose environmental and human rights abuses through film and photography. By purchasing this book, you are helping to support their Climate Campaign, which is centred on fighting for the rights of climate refugees

    On the Photometric Accuracy of RHESSI Imaging and Spectrosocopy

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    We compare the photometric accuracy of spectra and images in flares observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)}spacecraft. We test the accuracy of the photometry by comparing the photon fluxes obtained in different energy ranges from the spectral-fitting software SPEX with those fluxes contained in the images reconstructed with the Clean, MEM, MEM-Vis, Pixon, and Forward-fit algorithms. We quantify also the background fluxes, the fidelity of source geometries, and spatial spectra reconstructed with the five image reconstruction algorithms. We investigate the effects of grid selection, pixel size, field-of-view, and time intervals on the quality of image reconstruction. The detailed parameters and statistics are provided in an accompanying CD-ROM and web page. We find that Forward-fit, Pixon, and Clean have a robust convergence behavior and a photometric accuracy in the order of a few percents, while MEM does not converge optimally for large degrees of freedom (for large field-of-views and/or small pixel sizes), and MEM-Vis suffers in the case of time-variable sources. This comparative study documents the current status of the RHESSI spectral and imaging software, one year after launch.Comment: 2 Figures, full version on http://www.lmsal.com/~aschwand/eprints/2003_photo/index.htm

    The Effectiveness and Cost-Effectiveness of Spinal Cord Stimulation for Refractory Angina (RASCAL Study): A Pilot Randomized Controlled Trial

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    Background: Patients with “refractory angina” (RA) unsuitable for coronary revascularization experience high levels of hospitalization and poor health‐related quality of life. Randomized trials have shown spinal cord stimulation (SCS) to be a promising treatment for chronic stable angina and RA; however, none has compared SCS with usual care (UC). The aim of this pilot study was to address the key uncertainties of conducting a definitive multicenter trial to assess the clinical and cost‐effectiveness of SCS in RA patients, i.e., recruitment and retention of patients, burden of outcome measures, our ability to standardize UC in a UK NHS setting. Methods: RA patients deemed suitable were randomized in a 1:1 ratio to SCS plus UC (SCS group) or UC alone (UC group). We sought to assess: recruitment, uptake, and retention of patients; feasibility and acceptability of SCS treatment; the feasibility and acceptability of standardizing UC; and the feasibility and acceptability of the proposed trial outcome measures. Patient outcomes were assessed at baseline (prerandomization) and three and six months postrandomization. Results: We failed to meet our planned recruitment target (45 patients) and randomized 29 patients (15 SCS group, 14 UC group) over a 42‐month period across four sites. None of the study participants chose to withdraw following consent and randomization. With exception of two deaths, all completed evaluation at baseline and follow‐up. Although the study was not formally powered to compare outcomes between groups, we saw a trend toward larger improvements in both primary and secondary outcomes in the SCS group. Conclusions: While patient recruitment was found to be challenging, levels of participant retention, outcome completion, and acceptability of SCS therapy were high. A number of lessons are presented in order to take forward a future definitive pragmatic randomized trial

    Invasive Species Forecasting System: A Decision Support Tool for the U.S. Geological Survey: FY 2005 Benchmarking Report v.1.6

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    The National Institute of Invasive Species Science (NIISS), through collaboration with NASA's Goddard Space Flight Center (GSFC), recently began incorporating NASA observations and predictive modeling tools to fulfill its mission. These enhancements, labeled collectively as the Invasive Species Forecasting System (ISFS), are now in place in the NIISS in their initial state (V1.0). The ISFS is the primary decision support tool of the NIISS for the management and control of invasive species on Department of Interior and adjacent lands. The ISFS is the backbone for a unique information services line-of-business for the NIISS, and it provides the means for delivering advanced decision support capabilities to a wide range of management applications. This report describes the operational characteristics of the ISFS, a decision support tool of the United States Geological Survey (USGS). Recent enhancements to the performance of the ISFS, attained through the integration of observations, models, and systems engineering from the NASA are benchmarked; i.e., described quantitatively and evaluated in relation to the performance of the USGS system before incorporation of the NASA enhancements. This report benchmarks Version 1.0 of the ISFS
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