1,192 research outputs found
Gaps in Thermal Design Guidelines in the Goddard Space Flight Center GOLD Rules
The GSFC (Goddard Space Flight Center) GOLD Rules (Goddard Open Learning Design; GSFC-STD-1000) provide a reasonably comprehensive list of guidelines for the design and testing of spacecraft and instruments based on the long heritage of successful GSFC missions. In general, all GSFC missions are required to comply with the GOLD Rules across a number of subsystems or to seek waivers to particular GOLD rules where compliance is not practical, either due to the risk posture of a mission or the cost and/or schedule associated with compliance. In thermal subsystems, GOLD Rules are applied to design margins throughout the project life cycle and include temperature margins, heater power margins, and two-phase transport margins. However, no explicit guidance is provided for two thermal design aspects: heater control authority (for stability requirements) and cryogenic design margins (which are often not reasonable to express in terms of temperatures). This can lead to ambiguity and inconsistency among projects when demonstrating GOLD Rules compliance. Two current GSFC projects, TIRS-2 (Thermal InfraRed Sensor 2) and WFIRST (Wide Field InfraRed Survey Telescope), are both missions with cryogenic aspects and active thermal control for stability. This paper seeks to outline the characterization of cryogenic margins during the design process for TIRS-2 and WFIRST as well as the project derived guidelines for heater control authority margin. This effort serves as potential first steps for updating the GOLD Rules to address these two areas in guiding thermal designs at GSFC
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An Application of Spatially Based Crash Analyses and Road Safety Investigations to Increase Older Driver Safety
Arguably the greatest issue facing the transportation profession is the ability to provide social equity with regards to both safety and mobility given the aging population. Given the overall dominance of the automobile within the transportation system, the ability to provide feasible alternatives is daunting. This fact, when coupled with the well-documented challenges of older drivers, underscores the need for improved safety features and system-wide safety approaches with a focus on the older driver. This paper describes an application of spatial crash analysis and road safety investigations that were employed in Massachusetts with a direct focus on the older driver. Specifically, the paper outlines an approach for identifying high crash locations for older drivers and presents the results of older driver focused road safety investigations for selected locations. The research approach targets both intersections and roadway segments identifying locations where older drivers are overrepresented in crashes. The road safety investigations resulted in recommended countermeasures aimed at mitigating the older driver crash problem at the identified locations. Although the resulting countermeasures, which were based upon established literature such as the Older Driver Design Handbook, included a full spectrum of recommendations, a specific emphasis was placed upon short-term and low cost measures that could be readily employed. Techniques to identify relationships between high crash location identification methods and the recommended countermeasures for the identified locations are considered. Ultimately the application of these techniques may provide transportation professionals with a means to associate specific older driver focused countermeasures with the results of particular methods of high crash location identification
2005 The Maine Warden Service and The State of Maine: A Contemporary and Historical Overview
Multi facet changes in many aspects of the State of Maine has not necessarily been followed by proportional changes in the structure of the Maine Warden Service. The following areas will be reviewed in this report Increased Population -A review of population trends in the state from 1970 to 1997. Reference will be made to population movements in the state creating more of an interaction between people and wildlife. Increased Access - Road access to remote sections of the state has increased dramatically over the past 20 years; creating increased opportunity for recreational use. Development of water access sites allows for more opportunity to enjoy water related sports. Expanded Constituency and User Trends - Hunting, fishing , and trapping are still popular but increased interest and industry developments in other outdoor related activities has created a new workload. Increased Responsibilities - Increased responsibilities through user trends and mandates Reduced Warden Service Personnel - Structure of the Maine \Varden Service peaked in 197 5. Restructuring since that time has left less working officers for our current operation. Reduced Available Work Hours and Labor Issues - Today Wardens are faced with time constraints that were unheard of 20 years ago. A look at work schedules and labor mandates show the changes in service provided.https://digitalcommons.usm.maine.edu/maine-ifw/1000/thumbnail.jp
Design and Requirements Creep In A Build-To-Print Mission
Build-to-Print designs, or rebuilds of flight proven designs, are attractive to mission stakeholders, as they give the appearance of minimal engineering development cost, risk, and schedule. The reality is that seldom is a project an exact duplicate of a predecessor. Mission reclassification, improvements in hardware, and science objective changes can all serve as a source of requirements and design creep and have ramifications often not fully anticipated during initial proposals. The Thermal Infrared Sensor Instrument (TIRS) was a late addition to the LandSat-8 program to provide infrared imaging to measure evapotranspiration for water cycle management. To meet the launch requirements for LandSat-8, instrument design life requirements were relaxed, the sensor development expedited, and technology development was minimized. Consequently, TIRS was designed as a higher risk instrument, with less redundancy than an instrument critical to mission success. After the successful LandSat-8 launch in 2013 and instrument performance, a rebuild of the instrument for the next LandSat spacecraft was included in the baseline mission success criteria. This paper discusses the technical challenges encountered during the rebuild of the TIRS-2 (Thermal Infrared Sensor 2) instrument and the resultant impacts on the thermal system design
Effect of response format for clinical vignettes on reporting quality of physician practice
<p>Abstract</p> <p>Background</p> <p>Clinical vignettes have been used widely to compare quality of clinical care and to assess variation in practice, but the effect of different response formats has not been extensively evaluated. Our objective was to compare three clinical vignette-based survey response formats – open-ended questionnaire (A), closed-ended (multiple-choice) questionnaire with deceptive response items mixed with correct items (B), and closed-ended questionnaire with only correct items (C) – in rheumatologists' pre-treatment assessment for tumor-necrosis-factor (TNF) blocker therapy.</p> <p>Methods</p> <p><b><it>Study design</it></b>: Prospective randomized study. <b><it>Setting</it></b>: Rheumatologists attending the 2004 French Society of Rheumatology meeting. Physicians were given a vignette describing the history of a fictitious woman with active rheumatoid arthritis, who was a candidate for therapy with TNF blocking agents, and then were randomized to receive questionnaire A, B, or C, each containing the same four questions but with different response formats, that asked about their pretreatment assessment. <b><it>Measurements</it></b>: Long (recommended items) and short (mandatory items) checklists were developed for pretreatment assessment for TNF-blocker therapy, and scores were expressed on the basis of responses to questionnaires A, B, and C as the percentage of respondents correctly choosing explicit items on these checklists. <b><it>Statistical analysis</it></b>: Comparison of the selected items using pairwise Chi-square tests with Bonferonni correction for variables with statistically significant differences.</p> <p>Results</p> <p>Data for all surveys distributed (114 As, 118 Bs, and 118 Cs) were complete and available for analysis. The percentage of questionnaire A, B, and C respondents for whom data was correctly complete for the short checklist was 50.4%, 84.0% and 95.0%, respectively, and was 0%, 5.0% and 5.9%, respectively, for the long version. As an example, 65.8%, 85.7% and 95.8% of the respondents of A, B, and C questionnaires, respectively, correctly identified the need for tuberculin skin test (p < 0.0001).</p> <p>Conclusion</p> <p>In evaluating clinical practice with use of a clinical vignette, a multiple-choice format rather than an open-ended format overestimates physician performance. The insertion of deceptive response items mixed with correct items in closed-ended (multiple-choice) questionnaire failed to avoid this overestimation.</p
The Quality Improvement Demonstration Study: An example of evidence-based policy-making in practice
<p>Abstract</p> <p>Background</p> <p>Randomized trials have long been the gold-standard for evaluating clinical practice. There is growing recognition that rigorous studies are similarly needed to assess the effects of policy. However, these studies are rarely conducted. We report on the Quality Improvement Demonstration Study (QIDS), an example of a large randomized policy experiment, introduced and conducted in a scientific manner to evaluate the impact of large-scale governmental policy interventions.</p> <p>Methods</p> <p>In 1999 the Philippine government proposed sweeping reforms in the National Health Sector Reform Agenda. We recognized the unique opportunity to conduct a social experiment. Our ongoing goal has been to generate results that inform health policy. Early on we concentrated on developing a multi-institutional collaborative effort. The QIDS team then developed hypotheses that specifically evaluated the impact of two policy reforms on both the delivery of care and long-term health status in children. We formed an experimental design by randomizing matched blocks of three communities into one of the two policy interventions plus a control group. Based on the reform agenda, one arm of the experiment provided expanded insurance coverage for children; the other introduced performance-based payments to hospitals and physicians. Data were collected in household, hospital-based patient exit, and facility surveys, as well as clinical vignettes, which were used to assess physician practice. Delivery of services and health status were evaluated at baseline and after the interventions were put in place using difference-in-difference estimation.</p> <p>Results</p> <p>We found and addressed numerous challenges conducting this study, namely: formalizing the experimental design using the existing health infrastructure; securing funding to do research coincident with the policy reforms; recognizing biases and designing the study to account for these; putting in place a broad data collection effort to account for unanticipated findings; introducing sustainable policy interventions based on the reform agenda; and providing results in real-time to policy makers through a combination of venues.</p> <p>Conclusion</p> <p>QIDS demonstrates that a large, prospective, randomized controlled policy experiment can be successfully implemented at a national level as part of sectoral reform. While we believe policy experiments should be used to generate evidence-based health policy, to do this requires opportunity and trust, strong collaborative relationships, and timing. This study nurtures the growing attitude that translation of scientific findings from the bedside to the community can be done successfully and that we should raise the bar on project evaluation and the policy-making process.</p
Comparison of soil properties measurements in pipeline corrosion estimation
Soil corrosion is a hazardous electrochemical process that affects buried metals in contact with soil. Corrosion in soils resembles atmospheric corrosion with corrosion rates usually higher and depending on the soil type. There are numerous properties of soil and thus soils can be classified in many different ways. Soil resistivity is one of the main indicators of soil corrosivity and thus of the hazardous impact the soil has on metal materials in soil environment, although it is not the only parameter affecting the risk of corrosion damage. In this work on-site measurements and laboratory measurements of soil characteristics are performed and compared. On- site measurements include measuring the redox potential and soil resistivity by Wenner 4-pin method, while the measurements in laboratory include measuring soil conductivity, as well as moisture content, pH, content of sulphates, chlorides and sulfides and polarization measurements, which give the most accurate results. The measurements have shown that if the Wenner 4- pin method is performed in a convenient way the obtained results are not precise but can give an indicative picture of the corrosivity of the observed soil
Methods for pronunciation assessment in computer aided language learning
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 149-176).Learning a foreign language is a challenging endeavor that entails acquiring a wide range of new knowledge including words, grammar, gestures, sounds, etc. Mastering these skills all require extensive practice by the learner and opportunities may not always be available. Computer Aided Language Learning (CALL) systems provide non-threatening environments where foreign language skills can be practiced where ever and whenever a student desires. These systems often have several technologies to identify the different types of errors made by a student. This thesis focuses on the problem of identifying mispronunciations made by a foreign language student using a CALL system. We make several assumptions about the nature of the learning activity: it takes place using a dialogue system, it is a task- or game-oriented activity, the student should not be interrupted by the pronunciation feedback system, and that the goal of the feedback system is to identify severe mispronunciations with high reliability. Detecting mispronunciations requires a corpus of speech with human judgements of pronunciation quality. Typical approaches to collecting such a corpus use an expert phonetician to both phonetically transcribe and assign judgements of quality to each phone in a corpus. This is time consuming and expensive. It also places an extra burden on the transcriber. We describe a novel method for obtaining phone level judgements of pronunciation quality by utilizing non-expert, crowd-sourced, word level judgements of pronunciation. Foreign language learners typically exhibit high variation and pronunciation shapes distinct from native speakers that make analysis for mispronunciation difficult. We detail a simple, but effective method for transforming the vowel space of non-native speakers to make mispronunciation detection more robust and accurate. We show that this transformation not only enhances performance on a simple classification task, but also results in distributions that can be better exploited for mispronunciation detection. This transformation of the vowel is exploited to train a mispronunciation detector using a variety of features derived from acoustic model scores and vowel class distributions. We confirm that the transformation technique results in a more robust and accurate identification of mispronunciations than traditional acoustic models.by Mitchell A. Peabody.Ph.D
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Are there valid proxy measures of clinical behaviour?
Background: Accurate measures of health professionals' clinical practice are critically important to guide health policy decisions, as well as for professional self-evaluation and for research-based investigation of clinical practice and process of care. It is often not feasible or ethical to measure behaviour through direct observation, and rigorous behavioural measures are difficult and costly to use. The aim of this review was to identify the current evidence relating to the relationships between proxy measures and direct measures of clinical behaviour. In particular, the accuracy of medical record review, clinician self-reported and patient-reported behaviour was assessed relative to directly observed behaviour.
Methods: We searched: PsycINFO; MEDLINE; EMBASE; CINAHL; Cochrane Central Register of Controlled Trials; science/social science citation index; Current contents (social & behavioural med/clinical med); ISI conference proceedings; and Index to Theses. Inclusion criteria: empirical, quantitative studies; and examining clinical behaviours. An independent, direct measure of behaviour (by standardised patient, other trained observer or by video/audio recording) was considered the 'gold standard' for comparison. Proxy measures of behaviour included: retrospective self-report; patient-report; or chart-review. All titles, abstracts, and full text articles retrieved by electronic searching were screened for inclusion and abstracted independently by two reviewers. Disagreements were resolved by discussion with a third reviewer where necessary.
Results: Fifteen reports originating from 11 studies met the inclusion criteria. The method of direct measurement was by standardised patient in six reports, trained observer in three reports, and audio/video recording in six reports. Multiple proxy measures of behaviour were compared in five of 15 reports. Only four of 15 reports used appropriate statistical methods to compare measures. Some direct measures failed to meet our validity criteria. The accuracy of patient report and chart review as proxy measures varied considerably across a wide range of clinical actions. The evidence for clinician self-report was inconclusive.
Conclusion: Valid measures of clinical behaviour are of fundamental importance to accurately identify gaps in care delivery, improve quality of care, and ultimately to improve patient care. However, the evidence base for three commonly used proxy measures of clinicians' behaviour is very limited. Further research is needed to better establish the methods of development, application, and analysis for a range of both direct and proxy measures of behaviour
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