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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Research priorities and plans for the International Space Station-results of the 'REMAP' Task Force

Recent events in the International Space Station (ISS) Program have resulted in the necessity to re-examine the research priorities and research plans for future years. Due to both technical and fiscal resource constraints expected on the International Space Station, it is imperative that research priorities be carefully reviewed and clearly articulated. In consultation with OSTP and the Office of Management and budget (OMB), NASA's Office of Biological and Physical Research (OBPR) assembled an ad-hoc external advisory committee, the Biological and Physical Research Maximization and Prioritization (REMAP) Task Force. This paper describes the outcome of the Task Force and how it is being used to define a roadmap for near and long-term Biological and Physical Research objectives that supports NASA's Vision and Mission. Additionally, the paper discusses further prioritizations that were necessitated by budget and ISS resource constraints in order to maximize utilization of the International Space Station. Finally, a process has been developed to integrate the requirements for this prioritized research with other agency requirements to develop an integrated ISS assembly and utilization plan that maximizes scientific output. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

NASA Center HQS↗
NASA NTRS2003

The Interplanetary Internet: a communications infrastructure for Mars exploration

A strategy is being developed whereby the current set of internationally standardized space data communications protocols can be incrementally evolved so that a first version of an operational "Interplanetary Internet" is feasible by the end of the decade. This paper describes its architectural concepts, discusses the current set of standard space data communications capabilities that exist to support Mars exploration and reviews proposed new developments. We also speculate that these current capabilities can grow to support future scenarios where human intelligence is widely distributed across the Solar System and day-to-day communications dialog between planets is routine. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

Internet/standards↗
NASA NTRS2003

Physical sciences research plans for the International Space Station

The restructuring of the research capabilities of the International Space Station has forced a reassessment of the Physical Sciences research plans and a re-targeting of the major scientific thrusts. The combination of already selected peer-reviewed flight investigations with the initiation of new research and technology programs will allow the maximization of the ISS scientific and technological potential. Fundamental and applied research will use a combination of ISS-based facilities, ground-based activities, and other experimental platforms to address issues impacting fundamental knowledge, industrial and medical applications on Earth, and the technology required for human space exploration. The current flight investigation research plan shows a large number of principal investigators selected to use the remaining planned research facilities. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

manned↗
NASA NTRS2003

Physiology, medicine, long-duration space flight and the NSBRI

The hazards of long-duration space flight are real and unacceptable. In order for humans to participate effectively in long-duration orbital missions or continue the exploration of space, we must first secure the health of the astronaut and the success of such missions by assessing in detail the biomedical risks of space flight and developing countermeasures to these hazards. Acquiring the understanding necessary for building a sound foundation for countermeasure development requires an integrated approach to research in physiology and medicine and a level of cooperative action uncommon in the biomedical sciences. The research program of the National Space Biomedical Research Institute (NSBRI) was designed to accomplish just such an integrated research goal, ameliorating or eliminating the biomedical risks of long-duration space flight and enabling safe and productive exploration of space. The fruits of these labors are not limited to the space program. We can also use the gained understanding of the effects and mechanisms of the physiological changes engendered in space and the applied preventive and rehabilitative methods developed to combat these changes to the benefit of those on Earth who are facing similar physiological and psychological difficulties. This paper will discuss the innovative approach the NSBRI has taken to integrated research management and will present some of the successes of this approach. c2003 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.

NASA Discipline General Space Life Sciences↗
NASA NTRS2003

Characteristics of covert and overt visual orienting: Evidence from attentional and oculomotor capture

Five visual search experiments found oculomotor and attentional capture consistent with predictions of contingent orienting, contrary to claims that oculomotor capture is purely stimulus driven. Separate saccade and attend-only conditions contained a color target appearing either singly, with an onset or color distractor, or both. In singleton mode, onsets produced oculomotor and attentional capture. In feature mode, capture was absent or greatly reduced, providing evidence for top-down modulation of both types of capture. Although attentional capture by color abstractors was present throughout, oculomotor capture by color occurred only when accompanied by transient change, providing evidence for a dissociation between oculomotor and attentional capture. Oculomotor and attentional capture appear to be mediated by top-down attentional control settings, but transient change may be necessary for oculomotor capture. ((c) 2003 APA, all rights reserved).

Clinical Trial↗
NASA NTRS2003

Electronic nose for space program applications

The ability to monitor air contaminants in the shuttle and the International Space Station is important to ensure the health and safety of astronauts, and equipment integrity. Three specific space applications have been identified that would benefit from a chemical monitor: (a) organic contaminants in space cabin air; (b) hypergolic propellant contaminants in the shuttle airlock; (c) pre-combustion signature vapors from electrical fires. NASA at Kennedy Space Center (KSC) is assessing several commercial and developing electronic noses (E-noses) for these applications. A short series of tests identified those E-noses that exhibited sufficient sensitivity to the vapors of interest. Only two E-noses exhibited sufficient sensitivity for hypergolic fuels at the required levels, while several commercial E-noses showed sufficient sensitivity of common organic vapors. These E-noses were subjected to further tests to assess their ability to identify vapors. Development and testing of E-nose models using vendor supplied software packages correctly identified vapors with an accuracy of 70-90%. In-house software improvements increased the identification rates between 90 and 100%. Further software enhancements are under development. Details on the experimental setup, test protocols, and results on E-nose performance are presented in this paper along with special emphasis on specific software enhancements. c2003 Elsevier Science B.V. All rights reserved.

Air Pollution, Indoor/analysis↗
NASA NTRS2003

Search-based optimization

The problem of determining the minimum cost hypothetical ancestral sequences for a given cladogram is known to be NP-complete (Wang and Jiang, 1994). Traditionally, point estimations of hypothetical ancestral sequences have been used to gain heuristic, upper bounds on cladogram cost. These include procedures with such diverse approaches as non-additive optimization of multiple sequence alignment, direct optimization (Wheeler, 1996), and fixed-state character optimization (Wheeler, 1999). A method is proposed here which, by extending fixed-state character optimization, replaces the estimation process with a search. This form of optimization examines a diversity of potential state solutions for cost-efficient hypothetical ancestral sequences and can result in greatly more parsimonious cladograms. Additionally, such an approach can be applied to other NP-complete phylogenetic optimization problems such as genomic break-point analysis. c2003 The Willi Hennig Society. Published by Elsevier Science (USA). All rights reserved.

Non-NASA Center↗
NASA NTRS2003

Molecular modeling of polymer composite-analyte interactions in electronic nose sensors

We report a molecular modeling study to investigate the polymer-carbon black (CB) composite-analyte interactions in resistive sensors. These sensors comprise the JPL electronic nose (ENose) sensing array developed for monitoring breathing air in human habitats. The polymer in the composite is modeled based on its stereoisomerism and sequence isomerism, while the CB is modeled as uncharged naphthalene rings with no hydrogens. The Dreiding 2.21 force field is used for the polymer, solvent molecules and graphite parameters are assigned to the carbon black atoms. A combination of molecular mechanics (MM) and molecular dynamics (NPT-MD and NVT-MD) techniques are used to obtain the equilibrium composite structure by inserting naphthalene rings in the polymer matrix. Polymers considered for this work include poly(4-vinylphenol), polyethylene oxide, and ethyl cellulose. Analytes studied are representative of both inorganic and organic compounds. The results are analyzed for the composite microstructure by calculating the radial distribution profiles as well as for the sensor response by predicting the interaction energies of the analytes with the composites. c2003 Elsevier Science B.V. All rights reserved.

NASA Center JPL↗
NASA NTRS2003

Implied alignment: a synapomorphy-based multiple-sequence alignment method and its use in cladogram search

A method to align sequence data based on parsimonious synapomorphy schemes generated by direct optimization (DO; earlier termed optimization alignment) is proposed. DO directly diagnoses sequence data on cladograms without an intervening multiple-alignment step, thereby creating topology-specific, dynamic homology statements. Hence, no multiple-alignment is required to generate cladograms. Unlike general and globally optimal multiple-alignment procedures, the method described here, implied alignment (IA), takes these dynamic homologies and traces them back through a single cladogram, linking the unaligned sequence positions in the terminal taxa via DO transformation series. These "lines of correspondence" link ancestor-descendent states and, when displayed as linearly arrayed columns without hypothetical ancestors, are largely indistinguishable from standard multiple alignment. Since this method is based on synapomorphy, the treatment of certain classes of insertion-deletion (indel) events may be different from that of other alignment procedures. As with all alignment methods, results are dependent on parameter assumptions such as indel cost and transversion:transition ratios. Such an IA could be used as a basis for phylogenetic search, but this would be questionable since the homologies derived from the implied alignment depend on its natal cladogram and any variance, between DO and IA + Search, due to heuristic approach. The utility of this procedure in heuristic cladogram searches using DO and the improvement of heuristic cladogram cost calculations are discussed. c2003 The Willi Hennig Society. Published by Elsevier Science (USA). All rights reserved.

Non-NASA Center↗
NASA NTRS2003

Iterative pass optimization of sequence data

The problem of determining the minimum-cost hypothetical ancestral sequences for a given cladogram is known to be NP-complete. This "tree alignment" problem has motivated the considerable effort placed in multiple sequence alignment procedures. Wheeler in 1996 proposed a heuristic method, direct optimization, to calculate cladogram costs without the intervention of multiple sequence alignment. This method, though more efficient in time and more effective in cladogram length than many alignment-based procedures, greedily optimizes nodes based on descendent information only. In their proposal of an exact multiple alignment solution, Sankoff et al. in 1976 described a heuristic procedure--the iterative improvement method--to create alignments at internal nodes by solving a series of median problems. The combination of a three-sequence direct optimization with iterative improvement and a branch-length-based cladogram cost procedure, provides an algorithm that frequently results in superior (i.e., lower) cladogram costs. This iterative pass optimization is both computation and memory intensive, but economies can be made to reduce this burden. An example in arthropod systematics is discussed. c2003 The Willi Hennig Society. Published by Elsevier Science (USA). All rights reserved.

NASA Discipline Evolutionary Biology↗
NASA NTRS2003

Multi-scale variation in spatial heterogeneity for microbial community structure in an eastern Virginia agricultural field

To better understand the distribution of soil microbial communities at multiple spatial scales, a survey was conducted to examine the spatial organization of community structure in a wheat field in eastern Virginia (USA). Nearly 200 soil samples were collected at a variety of separation distances ranging from 2.5 cm to 11 m. Whole-community DNA was extracted from each sample, and community structure was compared using amplified fragment length polymorphism (AFLP) DNA fingerprinting. Relative similarity was calculated between each pair of samples and compared using geostatistical variogram analysis to study autocorrelation as a function of separation distance. Spatial autocorrelation was found at scales ranging from 30 cm to more than 6 m, depending on the sampling extent considered. In some locations, up to four different correlation length scales were detected. The presence of nested scales of variability suggests that the environmental factors regulating the development of the communities in this soil may operate at different scales. Kriging was used to generate maps of the spatial organization of communities across the plot, and the results demonstrated that bacterial distributions can be highly structured, even within a habitat that appears relatively homogeneous at the plot and field scale. Different subsets of the microbial community were distributed differently across the plot, and this is thought to be due to the variable response of individual populations to spatial heterogeneity associated with soil properties. c2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

NASA Discipline Life Support Systems↗
NASA NTRS2003

Effect of gravitational sedimentation on simulated aerosol dispersion in the human acinus

We studied the effect of gravitational sedimentation on the dispersion of 0.5 and 1 micrometer-diameter particle boluses within a two-dimensional symmetric six-generation model of the human acinus. Boluses were introduced at the beginning of a 2-s inspiration immediately followed by a 4-s expiration, in normal gravity (1 G) and in the absence of gravity (0 G). The flow corresponded to a flow rate at the mouth of 500 ml/s. In 0 G, simulated dispersion (Hsim) was 16 ml for both particle sizes. In 1 G, Hsim was 71 and 242 ml for 0.5 and 1 micrometer-diameter particles, respectively, showing the effect of gravitational sedimentation. The difference between experimental data (J. Appl. Physiol. 86 (1999) 1402) and simulations was independent of particle size. This suggests that the residual dispersion was independent of the intrinsic properties of the particles and was more likely due to other mechanisms such as ventilation inhomogeneities, cardiogenic oscillations and alveolar wall motion. c2003 Elsevier Science Ltd. All rights reserved.

short duration↗
NASA NTRS2003

Spaceflight hardware for conducting plant growth experiments in space: the early years 1960-2000

The best strategy for supporting long-duration space missions is believed to be bioregenerative life support systems (BLSS). An integral part of a BLSS is a chamber supporting the growth of higher plants that would provide food, water, and atmosphere regeneration for the human crew. Such a chamber will have to be a complete plant growth system, capable of providing lighting, water, and nutrients to plants in microgravity. Other capabilities include temperature, humidity, and atmospheric gas composition controls. Many spaceflight experiments to date have utilized incomplete growth systems (typically having a hydration system but lacking lighting) to study tropic and metabolic changes in germinating seedlings and young plants. American, European, and Russian scientists have also developed a number of small complete plant growth systems for use in spaceflight research. Currently we are entering a new era of experimentation and hardware development as a result of long-term spaceflight opportunities available on the International Space Station. This is already impacting development of plant growth hardware. To take full advantage of these new opportunities and construct innovative systems, we must understand the results of past spaceflight experiments and the basic capabilities of the diverse plant growth systems that were used to conduct these experiments. The objective of this paper is to describe the most influential pieces of plant growth hardware that have been used for the purpose of conducting scientific experiments during the first 40 years of research. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Non-NASA Center↗
NASA NTRS2003

Farming in space: environmental and biophysical concerns

The colonization of space will depend on our ability to routinely provide for the metabolic needs (oxygen, water, and food) of a crew with minimal re-supply from Earth. On Earth, these functions are facilitated by the cultivation of plant crops, thus it is important to develop plant-based food production systems to sustain the presence of mankind in space. Farming practices on earth have evolved for thousands of years to meet both the demands of an ever-increasing population and the availability of scarce resources, and now these practices must adapt to accommodate the effects of global warming. Similar challenges are expected when earth-based agricultural practices are adapted for space-based agriculture. A key variable in space is gravity; planets (e.g. Mars, 1/3 g) and moons (e.g. Earth's moon, 1/6 g) differ from spacecraft orbiting the Earth (e.g. Space stations) or orbital transfer vehicles that are subject to microgravity. The movement of heat, water vapor, CO2 and O2 between plant surfaces and their environment is also affected by gravity. In microgravity, these processes may also be affected by reduced mass transport and thicker boundary layers around plant organs caused by the absence of buoyancy dependent convective transport. Future space farmers will have to adapt their practices to accommodate microgravity, high and low extremes in ambient temperatures, reduced atmospheric pressures, atmospheres containing high volatile organic carbon contents, and elevated to super-elevated CO2 concentrations. Farming in space must also be carried out within power-, volume-, and mass-limited life support systems and must share resources with manned crews. Improved lighting and sensor technologies will have to be developed and tested for use in space. These developments should also help make crop production in terrestrial controlled environments (plant growth chambers and greenhouses) more efficient and, therefore, make these alternative agricultural systems more economically feasible food production systems. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Review↗
NASA NTRS2003

Long-term changes in amphetamine-induced reinforcement and aversion in rats following exposure to 56Fe particle

Exposing rats to heavy particles produces alterations in the functioning of dopaminergic neurons and in the behaviors that depend upon the integrity of the dopaminergic system. Two of these dopamine-dependent behaviors include amphetamine-induced reinforcement, measure using the conditioned place preference procedure, and amphetamine-induced reinforcement, measured using the conditioned place preference procedure, and amphetamine-induced aversion, measured using the conditioned taste aversion. Previous research has shown that exposing rats to 1.0 Gy of 1GeV/n 56Fe particles produced a disruption of an amphetamine-induced taste aversion 3 days following exposure, but produced an apparent enhancement of the aversion 112 days following exposure. The present experiments were designed to provide a further evaluation of these results by examining taste aversion learning 154 days following exposure to 1.0 Gy 56Fe particles and to establish the convergent validity of the taste aversion results by looking at the effects of exposure on the establishment of an amphetamine-induced conditioned place preference 3, 7, and 16 weeks following irradiation. The taste aversion results failed to confirm the apparent enhancement of the amphetamine-induced CTA observed in the prior experiment. However, exposure to 56Fe particles prevented the acquisition of amphetamine-induced place preference at all three-time intervals. The results are interpreted as indicating that exposure to heavy particles can produce long-term changes in behavioral functioning. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Non-NASA Center↗
NASA NTRS2003

Planetary protection and the search for life beneath the surface of Mars

The search for traces of extinct and extant life on Mars will be extended to beneath the surface of the planet. Current data from Mars missions suggesting the presence of liquid water early in Mars' history and mathematical modeling of the fate of water on Mars imply that liquid water may exist deep beneath the surface of Mars. This leads to the hypothesis that life may exist deep beneath the Martian surface. One possible scenario to look for life on Mars involves a series of unmanned missions culminating with a manned mission drilling deep into the Martian subsurface (approximately 3Km), collecting samples, and conducting preliminary analyses to select samples for return to earth. This mission must address both forward and back contamination issues, and falls under planetary protection category V. Planetary protection issues to be addressed include provisions stating that the inevitable deposition of earth microbes by humans should be minimized and localized, and that earth microbes and organic material must not contaminate the Martian subsurface. This requires that the drilling equipment be sterilized prior to use. Further, the collection, containment and retrieval of the sample must be conducted such that the crew is protected and that any materials returning to earth are contained (i.e., physically and biologically isolated) and the chain of connection with Mars is broken. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

NASA Discipline Exobiology↗
NASA NTRS2003

Issues of exploration: human health and wellbeing during a mission to Mars

Today, the tools are in our hands to enable us to travel away from our home planet and become citizens of the solar system. Even now, we are seriously beginning to develop the robust infrastructure that will make the 21st century the Century of Space Travel. But this bold step must be taken with due concern for the health, safety and wellbeing of future space explorers. Our long experience with space biomedical research convinces us that, if we are to deal effectively with the medical and biomedical issues of exploration, then dramatic and bold steps are also necessary in this field. We can no longer treat the human body as if it were composed of muscles, bones, heart and brain acting independently. Instead, we must lead the effort to develop a fully integrated view of the body, with all parts connected and fully interacting in a realistic way. This paper will present the status of current (2000) plans by the National Space Biomedical Research Institute to initiate research in this area of integrative physiology and medicine. Specifically, three example projects are discussed as potential stepping stones towards the ultimate goal of producing a digital human. These projects relate to developing a functional model of the human musculoskeletal system and the heart. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

NASA Discipline General Space Life Sciences↗
NASA NTRS2002

A geostatistical analysis of small-scale spatial variability in bacterial abundance and community structure in salt marsh creek bank sediments

Small-scale variations in bacterial abundance and community structure were examined in salt marsh sediments from Virginia's eastern shore. Samples were collected at 5 cm intervals (horizontally) along a 50 cm elevation gradient, over a 215 cm horizontal transect. For each sample, bacterial abundance was determined using acridine orange direct counts and community structure was analyzed using randomly amplified polymorphic DNA fingerprinting of whole-community DNA extracts. A geostatistical analysis was used to determine the degree of spatial autocorrelation among the samples, for each variable and each direction (horizontal and vertical). The proportion of variance in bacterial abundance that could be accounted for by the spatial model was quite high (vertical: 60%, horizontal: 73%); significant autocorrelation was found among samples separated by 25 cm in the vertical direction and up to 115 cm horizontally. In contrast, most of the variability in community structure was not accounted for by simply considering the spatial separation of samples (vertical: 11%, horizontal: 22%), and must reflect variability from other parameters (e.g., variation at other spatial scales, experimental error, or environmental heterogeneity). Microbial community patch size based upon overall similarity in community structure varied between 17 cm (vertical) and 35 cm (horizontal). Overall, variability due to horizontal position (distance from the creek bank) was much smaller than that due to vertical position (elevation) for both community properties assayed. This suggests that processes more correlated with elevation (e.g., drainage and redox potential) vary at a smaller scale (therefore producing smaller patch sizes) than processes controlled by distance from the creek bank. c2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Non-NASA Center↗