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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Exercise countermeasure protocol management expert system

Exercise will be used primarily to countermeasure against deconditioning on extended space flight. In this paper we describe the development and evaluation of an expert system for exercise countermeasure protocol management. Currently, the system includes two major subsystems: baseline prescription and prescription adjustment. The baseline prescription subsystem is designed to provide initial exercise prescriptions while prescription adjustment subsystem is designed to modify the initial prescription based on the exercised progress. The system runs under three different environments: PC, SUN workstation, and Symbolic machine. The inference engine, baseline prescription module, prescription adjustment module and explanation module are developed under the Symbolic environment by using the ART (Automated Reasoning Tool) software. The Sun environment handles database management features and interfaces with PC environment to obtain physical and physiological data from exercise units on-board during the flight. Eight subjects' data have been used to evaluate the system performance by comparing the prescription of nine experienced exercise physiologists and the one prescribed by the expert system. The results of the validation test indicated that the performance of the expert system was acceptable.

NASA Discipline Data Analysis↗
NASA NTRS1992

Field-testing the new DECtalk PC system for medical applications

Synthesized human speech has now reached a new level of performance. With the introduction of DEC's new DECtalk PC, the small system developer will have a very powerful tool for creative design. It has been our privilege to be involved in the beta-testing of this new device and to add a medical dictionary which covers a wide range of medical terminology. With the inherent board level understanding of speech synthesis and the medical dictionary, it is now possible to provide full digital speech output for all medical files and terms. The application of these tools will cover a wide range of options for the future and allow a new dimension in dealing with the complex user interface experienced in medical practice.

NASA Discipline Data Analysis↗
NASA NTRS1993

Earthbound applications for NASA's physician workstation

The dream of a space probe to Mars or an astronaut colony on the moon persists. Despite years of setbacks and delays, NASA continues to lay the foundation for a new frontier in space. The necessity of a self contained health maintenance facility is an integral part of this stellar venture. As a subsystem of this health maintenance facility, the physician or astronaut workstation was envisioned as the vehicle of interface between the computer resources of the space station and the care provider. Our efforts to define and build this interface have resulted in a series of programs which can now be tested and refined using earth-based applications. The modules which have dual-use application from the NASA workstation include: patient scheduling and master patient index, pharmacy, laboratory, medical library, problem list/progress notes, and digital medical records. Our current plan is to develop these tools as objects that can be assembled in a variety of configurations. This will allow the technology to be used by the private sector where each doctor can select the starting point of his outpatient office system and add modules as he makes progress in system integration and training.

NASA Discipline Number 70-30↗
NASA NTRS1997

Evaluation of cardiac rhythm disturbances during extravehicular activity

This study represents the first systematic evaluation of dysrhythmias before, during, and after spaceflight including extravehicular activity (EVA). The data, based on 7 Shuttle crew members, revealed a nonsignificant decrease in ventricular and supraventricular ectopy during EVA, suggesting that the incidence of dysrhythmias is no greater during EVA than with any other phase of a mission or preflight.

NASA Program Flight↗
NASA NTRS1993

Mathematical modelling of the human cardiovascular system in the presence of stenosis

This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large number of interconnected segments in the model. Values for the model parameters are based upon the published data on the physiological and rheological properties of blood. Computational results show how blood flow through various parts of the cardiovascular system is affected by stenosis in different blood vessels. No significant changes in the flow parameters of the cardiovascular system were found to occur when the reduction in the lumen diameter of the stenosed vessels was less than 65%.

NASA Program Data Analysis↗
NASA NTRS1997

Modeling the effects of exercise during 100% oxygen prebreathe on the risk of hypobaric decompression sickness

BACKGROUND: Several previous studies indicated that exercise during prebreathe with 100% O2 decreased the incidence of hypobaric decompression sickness (DCS). We report a meta-analysis of these investigations combined with a new study in our laboratory to develop a statistical model as a predictive tool for DCS. HYPOTHESIS: Exercise during prebreathe increases N2 elimination in a theoretical 360-min half-time compartment decreasing the incidence of DCS. METHODS: A dose-response probability tissue ratio (TR) model with 95% confidence limits was created for two groups, prebreathe with exercise (n = 113) and resting prebreathe (n = 113), using nonlinear regression analysis with maximum likelihood optimization. RESULTS: The model predicted that prebreathe exercise would reduce the residual N2 in a 360-min half-time compartment to a level analogous to that in a 180-min compartment. This finding supported the hypothesis. The incidence of DCS for the exercise prebreathe group was significantly decreased (Chi-Square = 17.1, p < 0.0001) from the resting prebreathe group. CONCLUSIONS: The results suggested that exercise during prebreathe increases tissue perfusion and N2 elimination approximately 2-fold and markedly lowers the risk of DCS. Based on the model, the prebreathe duration may be reduced from 240 min to a predicted 91 min for the protocol in our study, but this remains to be verified. The model provides a useful planning tool to develop and test appropriate prebreathe exercise protocols and to predict DCS risks for astronauts.

NASA Program Environmental Health↗
NASA NTRS1997

Regulation of body fluid volume and electrolyte concentrations in spaceflight

Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian rhythms. Atrial natriuretic peptide does not seem to play an important role in the control of natriuresis during spaceflight. Inflight activity of the sympathetic nervous system, assessed by measuring catecholamines and their metabolites and precursors in body fluids, generally seems to be no greater than on Earth, but this system is usually activated at landing. Collaborative experiments on the Mir and the International Space Station should provide more of the data needed from long-term flights, and perhaps help to resolve some of the discrepancies between U.S. and Russian data. The use of alternative methods that are easier to execute during spaceflight, such as collection of saliva instead of blood and urine, should permit more thorough study of circadian rhythms and rapid hormone changes in weightlessness. More investigations of dietary intake of fluid and electrolytes must be performed to understand regulatory processes. Additional hormones that may participate in these processes, such as other natriuretic hormones, should be determined during and after spaceflight. Alterations in body fluid volume and blood electrolyte concentrations during spaceflight have important consequences for readaptation to the 1-G environment. The current assessment of fluid and electrolyte status during weightlessness and at landing and our still incomplete understanding of the processes of adaptation to weightlessness and readaptation to Earth's gravity have resulted in the development of countermeasures that are only partly successful in reducing the postflight orthostatic intolerance experienced by astronauts and cosmonauts. More complete knowledge of these processes can be expected to produce countermeasures that are even more successful, as well as expand our comprehension of the range of adaptability of human physiologic processes.

NASA Discipline Number 18-10↗
NASA NTRS1994

The effect of blood volume loss on cardiovascular response to lower body negative pressure using a mathematical model

Different mathematical models of varying complexity have been proposed in recent years to study the cardiovascular (CV) system. However, only a few of them specifically address the response to lower body negative pressure (LBNP), a stress that can be applied in weightlessness to predict changes in orthostatic tolerance. Also, the simulated results produced by these models agree only partially with experimental observations. In contrast, the model proposed by Melchior et al., and modified by Karam et al. is a simple representation of the CV system capable of accurately reproducing observed LBNP responses up to presyncopal levels. There are significant changes in LBNP response due to a loss of blood volume and other alterations that occur in weightlessness and related one-g conditions such as bedrest. A few days of bedrest can cause up to 15% blood volume loss (BVL), with consequent decreases in both stroke volume and cardiac output, and increases in heart rate, mean arterial pressure, and total peripheral resistance. These changes are more pronounced at higher levels of LBNP. This paper presents the results of a simulation study using our CV model to examine the effect of BVL on LBNP response.

NASA Discipline Number 70-30↗
NASA NTRS1997

A mathematical model of diurnal variations in human plasma melatonin levels

Studies in animals and humans suggest that the diurnal pattern in plasma melatonin levels is due to the hormone's rates of synthesis, circulatory infusion and clearance, circadian control of synthesis onset and offset, environmental lighting conditions, and error in the melatonin immunoassay. A two-dimensional linear differential equation model of the hormone is formulated and is used to analyze plasma melatonin levels in 18 normal healthy male subjects during a constant routine. Recently developed Bayesian statistical procedures are used to incorporate correctly the magnitude of the immunoassay error into the analysis. The estimated parameters [median (range)] were clearance half-life of 23.67 (14.79-59.93) min, synthesis onset time of 2206 (1940-0029), synthesis offset time of 0621 (0246-0817), and maximum N-acetyltransferase activity of 7.17(2.34-17.93) pmol x l(-1) x min(-1). All were in good agreement with values from previous reports. The difference between synthesis offset time and the phase of the core temperature minimum was 1 h 15 min (-4 h 38 min-2 h 43 min). The correlation between synthesis onset and the dim light melatonin onset was 0.93. Our model provides a more physiologically plausible estimate of the melatonin synthesis onset time than that given by the dim light melatonin onset and the first reliable means of estimating the phase of synthesis offset. Our analysis shows that the circadian and pharmacokinetics parameters of melatonin can be reliably estimated from a single model.

NASA Discipline Number 70-10↗
NASA NTRS1996

Lessons from operational cardiovascular studies in space

The Space Shuttle program has produced a database of information on the cardiovascular responses to spaceflight, based on in-flight as well as pre- and post-flight assessments undertaken as part of the assessment of the health, safety, and efficiency of Shuttle crews. The methods used in routine cardiovascular assessments of Space Shuttle astronauts are reviewed, and the major findings of these investigations are presented.

NASA Program Data Analysis↗
NASA NTRS1999

CRITICA: coding region identification tool invoking comparative analysis

Gene recognition is essential to understanding existing and future DNA sequence data. CRITICA (Coding Region Identification Tool Invoking Comparative Analysis) is a suite of programs for identifying likely protein-coding sequences in DNA by combining comparative analysis of DNA sequences with more common noncomparative methods. In the comparative component of the analysis, regions of DNA are aligned with related sequences from the DNA databases; if the translation of the aligned sequences has greater amino acid identity than expected for the observed percentage nucleotide identity, this is interpreted as evidence for coding. CRITICA also incorporates noncomparative information derived from the relative frequencies of hexanucleotides in coding frames versus other contexts (i.e., dicodon bias). The dicodon usage information is derived by iterative analysis of the data, such that CRITICA is not dependent on the existence or accuracy of coding sequence annotations in the databases. This independence makes the method particularly well suited for the analysis of novel genomes. CRITICA was tested by analyzing the available Salmonella typhimurium DNA sequences. Its predictions were compared with the DNA sequence annotations and with the predictions of GenMark. CRITICA proved to be more accurate than GenMark, and moreover, many of its predictions that would seem to be errors instead reflect problems in the sequence databases. The source code of CRITICA is freely available by anonymous FTP (rdp.life.uiuc.edu in/pub/critica) and on the World Wide Web (http:/(/)rdpwww.life.uiuc.edu).

Non-NASA Center↗
NASA NTRS2000

An architecture for a brain-image database

The widespread availability of methods for noninvasive assessment of brain structure has enabled researchers to investigate neuroimaging correlates of normal aging, cerebrovascular disease, and other processes; we designate such studies as image-based clinical trials (IBCTs). We propose an architecture for a brain-image database, which integrates image processing and statistical operators, and thus supports the implementation and analysis of IBCTs. The implementation of this architecture is described and results from the analysis of image and clinical data from two IBCTs are presented. We expect that systems such as this will play a central role in the management and analysis of complex research data sets.

NASA Discipline Neuroscience↗
NASA NTRS1994

Computer simulation of the effect of dDAVP with saline loading on fluid balance after 24-hour head-down tilt

Fluid loading (FL) before Shuttle reentry is a countermeasure currently in use by NASA to improve the orthostatic tolerance of astronauts during reentry and postflight. The fluid load consists of water and salt tablets equivalent to 32 oz (946 ml) of isotonic saline. However, the effectiveness of this countermeasure has been observed to decrease with the duration of spaceflight. The countermeasure's effectiveness may be improved by enhancing fluid retention using analogs of vasopressin such as lypressin (LVP) and desmopressin (dDAVP). In a computer simulation study reported previously, we attempted to assess the improvement in fluid retention obtained by the use of LVP administered before FL. The present study is concerned with the use of dDAVP. In a recent 24-hour, 6 degree head-down tilt (HDT) study involving seven men, dDAVP was found to improve orthostatic tolerance as assessed by both lower body negative pressure (LBNP) and stand tests. The treatment restored Luft's cumulative stress index (cumulative product of magnitude and duration of LBNP) to nearly pre-bedrest level. The heart rate was lower and stroke volume was marginally higher at the same LBNP levels with administration of dDAVP compared to placebo. Lower heart rates were also observed with dDAVP during stand test, despite the lower level of cardiovascular stress. These improvements were seen with only a small but significant increase in plasma volume of approximately 3 percent. This paper presents a computer simulation analysis of some of the results of this HDT study.

NASA Discipline Cardiopulmonary↗
NASA NTRS2018

Challenges in Development of Online Visualization and Analysis Tools for Satellite Data

Over the years, various online visualization and analysis tools have been developed to facilitate satellite data access and help scientific users around the world to conduct research and develop applications (e.g., data product evaluation, what-if questions, etc.). For those who are new to satellite data products, using them can be a daunting task due to many obstacles in data processing such as data formats, complex data structures, special software packages, unfamiliar terminology, etc., especially when one is not sure whether a dataset is suitable for his/er research project. Even for experienced users, developing software for data processing and analysis can be a costly and time-consuming task. Online visualization tools can overcome many of these difficulties and allow users to focus on scientific questions. For example, Giovanni (the Geospatial Interactive Online Visualization and Analysis Infrastructure, https://giovanni.gsfc.nasa.gov), developed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), allows access over 1900 satellite and model variables in 82 measurement groups of 8 disciplines without downloading data and software. Main features include basic functions for data analysis and visualization, data provenance, output data in different formats (ASCII, NetCDF, GeoTIFF), and more. Over the years, ~1700 peer-reviewed publications in different disciplines have been benefited from Giovanni in research activities (e.g. initial investigation, what-if questions, product evaluation). Despite the success of online visualization and analysis tools, challenges and new opportunities still exist and more can be done with new requirements and technology. Examples are: a) how to increase the efficiency of dataset search by enhancing intuitive aspects; b) how to facilitate interdisciplinary research; c) how to provide data quality information; d) how to engage users to participate in data quality assessment; and more. NASA Earth Observing System Data and Information System (EOSDIS) satellite-based data products are processed at various levels ranging from Level 0 to Level 4. While most users use data products at higher levels (Level-3 and 4), products at lower levels are still important for case studies, algorithm development, ground validation, etc. In this presentation, we will use Giovanni as an example to present and discuss challenges and near-future opportunities for satellite data online visualization and analysis tools.

Liu, Zhong↗
NASA NTRS2010

VIIRS Product Evaluation at the Ocean PEATE

The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) mission will support the continuation of climate records generated from NASA missions. The NASA Science Data Segment (SDS) relies upon discipline-specific centers of expertise to evaluate the NPP data products for suitability as climate data records, The Ocean Product Evaluation and Analysis Tool Element (PEATE) will build upon Well established NASA capabilities within the Ocean Color program in order to evaluate the NPP Visible and Infrared Imager/Radiometer Suite (VIIRS) Ocean Color and Chlorophyll data products. The specific evaluation methods will support not only the evaluation of product quality but also the sources of differences with existing data records.

Patt, Frederick S.↗
NASA NTRS2010

Problem Reporting Taxonomy and Data Preparation Tool Evaluation

A member of the NASA Engineering and Safety Center (NESC) Systems Engineering Office (SEO) Technical Discipline Team (TDT) requested a SEO-managed activity to perform a gap analysis on the proposed NASA Standard 0006, "Common NASA Taxonomy for Problem Reporting, Analysis, and Resolution", and to create an input filter and set of instructions for using the data-mining/data-cleansing tool TechOasis1 with Space Shuttle Program (SSP) problem reporting data. The work that achieved these objectives and deployment of TechOasis are discussed in this report.

Beil, Robert J.↗
NASA NTRS1986

Performance Evaluation Tests for Environmental Research (PETER): evaluation of 114 measures

The goal of the Performance Evaluation Tests for Environmental Research (PETER) Program was to identify a set of measures of human capabilities for use in the study of environmental and other time-course effects. 114 measures studied in the PETER Program were evaluated and categorized into four groups based upon task stability and task definition. The Recommended category contained 30 measures that clearly obtained total stabilization and had an acceptable level of reliability efficiency. The Acceptable-But-Redundant category contained 15 measures. The 37 measures in the Marginal category, which included an inordinate number of slope and other derived measures, usually had desirable features which were outweighed by faults. The 32 measures in the Unacceptable category had either differential instability or weak reliability efficiency. It is our opinion that the 30 measures in the Recommended category should be given first consideration for environmental research applications. Further, it is recommended that information pertaining to preexperimental practice requirements and stabilized reliabilities should be utilized in repeated-measures environmental studies.

NASA Program Space Medicine↗
NASA NTRS2008

Description of the NASA Hypobaric Decompression Sickness Database (1982-1998)

The availability of high-speed computers, data analysis software, and internet communication are compelling reasons to describe and make available computer databases from many disciplines. Methods: Human research using hypobaric chambers to understand and then prevent decompression sickness (DCS) during space walks has been conducted at the Johnson Space Center (JSC) from 1982 to 1998. The data are archived in the NASA Hypobaric Decompression Sickness Database, within an Access 2003 Relational Database. Results: There are 548 records from 237 individuals that participated in 31 unique tests. Each record includes physical characteristics, the denitrogenation procedure that was tested, and the outcome of the test, such as the report of a DCS symptom and the intensity of venous gas emboli (VGE) detected with an ultrasound Doppler bubble detector as they travel in the venous blood along the pulmonary artery on the way to the lungs. We documented 84 cases of DCS and 226 cases where VGE were detected. The test altitudes were 10.2, 10.1, 6.5, 6.0, and 4.3 pounds per square inch absolute (psia). 346 records are from tests conducted at 4.3 psia, the operating pressure of the current U.S. space suit. 169 records evaluate the Staged 10.2 psia Decompression Protocol used by the Space Shuttle Program. The mean exposure time at altitude was 242.3 minutes (SD = 80.6), with a range from 120 to 360 minutes. Among our test subjects, 96 records of exposures are females. The mean age of all test subjects was 31.8 years (SD = 7.17), with a range from 20 to 54 years. Discussion: These data combined with other published databases and evaluated with metaanalysis techniques would extend our understanding about DCS. A better understanding about the cause and prevention of DCS would benefit astronauts, aviators, and divers.

Wessel, J. H., III↗