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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

X-33 LH2 Tank Failure Investigation Findings

This viewgraph presentation gives an overview of the X-33 LH2 tank failure investigation findings. The conclusions of the investigation include the following: (1) the inner skin microcracked and hydrogen infiltrated; (2) the cracks grew larger under pressure; (3) when pressure was removed, the cracks closed slightly; (4) when the tank was drained and warmed, the cracks closed and blocked the leak path; (5) FOD and debond areas provided an opportunity for a leak path; and (6) there is still hydrogen in the the other three lobes today.

Niedermeyer, Melinda↗
NASA NTRS2003

Finding the Onset of Convection in Main Sequence Stars

The primary goal of the work performed under this grant was to locate, if possible, the onset of subphotospheric convection zones in normal main sequence stars by using the presence of emission in high temperature lines in far ultraviolet spectra from the FUSE spacecraft as a proxy for convection. The change in stellar structure represented by this boundary between radiative and convective stars has always been difficult to find by other empirical means. A search was conducted through observations of a sample of A-type stars, which were somewhat hotter and more massive than the Sun, and which were carefully chosen to bridge the theoretically expected radiative/convective boundary line along the main sequence.

Simon, Theodore↗
NASA NTRS2003

Web-Enhanced Instruction and Learning: Findings of a Short- and Long-Term Impact Study and Teacher Use of NASA Web Resources

Over a three-year period, researchers and educators from the Pennsylvania State University (PSU), University Park, Pennsylvania, and the NASA Dryden Flight Research Center (DFRC), Edwards, California, worked together to analyze, develop, implement and evaluate materials and tools that enable teachers to use NASA Web resources effectively for teaching science, mathematics, technology and geography. Two conference publications and one technical paper have already been published as part of this educational research series on Web-based instruction and learning. This technical paper, Web-Enhanced Instruction and Learning: Findings of a Short- and Long-Term Impact Study, is the culminating report in this educational research series and is based on the final report submitted to NASA. This report describes the broad spectrum of data gathered from teachers about their experiences using NASA Web resources in the classroom. It also describes participating teachers responses and feedback about the use of the NASA Web-Enhanced Learning Environment Strategies reflection tool on their teaching practices. The reflection tool was designed to help teachers merge the vast array of NASA resources with the best teaching methods, taking into consideration grade levels, subject areas and teaching preferences. The teachers described their attitudes toward technology and innovation in the classroom and their experiences and perceptions as they attempted to integrate Web resources into science, mathematics, technology and geography instruction.

McCarthy, Marianne C.↗
NASA NTRS2004

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA s Origins program is a series of space telescopes designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, I will concentrate on the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with the Hubble Space Telescope through to the present day. I will introduce several of the tools that astronomers use to measure distances, measure velocities, and look backwards in time. I will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope, which is designed to find the first galaxies that formed in the distant past. I will finish with a short discussion of other missions in the Origins theme, including the Terrestrial Planet Finder.

Gardner, Jonathan P.↗
NASA NTRS1987

See-saw nystagmus and brainstem infarction: MRI findings

A patient with see-saw nystagmus had a lesion localized by Magnetic Resonance Imaging (MRI) to the paramedian ventral midbrain with involvement of the right interstitial nucleus of Cajal. This the first MRI study of see-saw nystagmus associated with a presumed brainstem vascular event. Our findings support animal and human studies suggesting that dysfunction of the interstitial nucleus of Cajal or its connections is central in this disorder.

Non-NASA Center↗
NASA NTRS2003

Finding Our Origins with the Hubble and James Webb Space Telescopes

NASA's Origins program is a series of space telescopes designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, I will concentrate on the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with the Hubble Space Telescope through to the present day. I will introduce several of the tools that astronomers use to measure distances, measure velocities, and look backwards in time. I will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope, which is designed to find the first galaxies that formed in the distant past. I will finish with a short discussion of other missions in the Origins theme, including the Terrestrial Planet Finder.

Gardner, Jonathan P.↗
NASA NTRS1998

Submaximal delayed-onset muscle soreness: correlations between MR imaging findings and clinical measures

PURPOSE: To assess correlations between muscle edema on magnetic resonance (MR) images and clinical indexes of muscle injury in delayed-onset muscle soreness (DOMS) produced by submaximal exercise protocols. MATERIALS AND METHODS: Sixteen subjects performed 36 elbow flexions ("biceps curls") at one of two submaximal workloads that emphasized eccentric contractions. Changes in MR imaging findings, plasma levels of creatine kinase, and pain scores were correlated. RESULTS: Both exercise protocols produced DOMS in all subjects. The best correlation was between change in creatine kinase level and volume of muscle edema on MR images, regardless of the workload. Correlations tended to be better with the easier exercise protocol. CONCLUSION: Whereas many previous studies of DOMS focused on intense exercise protocols to ensure positive results, the present investigation showed that submaximal workloads are adequate to produce DOMS and that correlations between conventionally measured indexes of injury may be enhanced at lighter exercise intensities.

Clinical Trial↗
NASA NTRS2004

Finding Bounded Rational Equilibria: Iterative Focusing - Part 1

A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality characterizing all real-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. It has recently been shown that the same information theoretic mathematical structure, known as Probability Collectives (PC) underlies both issues. This relationship between statistical physics and game theory allows techniques and insights from the one field to be applied to the other. In particular, PC provides a formal model-independent definition of the degree of rationality of a player and of bounded rationality equilibria. This pair of papers extends previous work on PC by introducing new computational approaches to effectively find bounded rationality equilibria of common-interest (team) games.

Wolpert, David H.↗
NASA NTRS2004

Finding Bounded Rational Equilibria: Alternative Lagrangians and Uncountable Move Spaces - Part 2

A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality characterizing all real-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. It has recently been shown that the same information theoretic mathematical structure, known as Probability Collectives (PC) underlies both issues. This relationship between statistical physics and game theory allows techniques and insights &om the one field to be applied to the other. In particular, PC provides a formal model-independent definition of the degree of rationality of a player and of bounded rationality equilibria. This pair of papers extends previous work on PC by introducing new computational approaches to effectively find bounded rationality equilibria of common-interest (team) games.

Wolpert, David H.↗
NASA NTRS2004

cWINNOWER algorithm for finding fuzzy dna motifs

The cWINNOWER algorithm detects fuzzy motifs in DNA sequences rich in protein-binding signals. A signal is defined as any short nucleotide pattern having up to d mutations differing from a motif of length l. The algorithm finds such motifs if a clique consisting of a sufficiently large number of mutated copies of the motif (i.e., the signals) is present in the DNA sequence. The cWINNOWER algorithm substantially improves the sensitivity of the winnower method of Pevzner and Sze by imposing a consensus constraint, enabling it to detect much weaker signals. We studied the minimum detectable clique size qc as a function of sequence length N for random sequences. We found that qc increases linearly with N for a fast version of the algorithm based on counting three-member sub-cliques. Imposing consensus constraints reduces qc by a factor of three in this case, which makes the algorithm dramatically more sensitive. Our most sensitive algorithm, which counts four-member sub-cliques, needs a minimum of only 13 signals to detect motifs in a sequence of length N = 12,000 for (l, d) = (15, 4). Copyright Imperial College Press.

Evaluation Studies↗
NASA NTRS2007

GRB 050826: A Subluminous Event at z=0.296 Finds Its Place in the Luminosity Distribution of Gamma-Ray Burst Afterglows

We present the optical identification and spectroscopy of the host galaxy of GRB 050826 at redshift z = 0.296 +/- 0.001. Image subtraction among observations obtained on three consecutive nights reveals a fading object 5 hr after the burst, confirming its identification as the optical afterglow of this event. Deep imaging shows that the optical afterglow is offset by 0.4" (1.76 kpc) from the center of its irregular host galaxy, which is typical for long-duration gamma-ray bursts. Combining these results with X-ray measurements acquired by the Swift XRT instrument, we find that GRB 050826 falls entirely within the subluminous, subenergetic group of long gamma-ray bursts at low redshift (z less than or equal to 0.3). The results are discussed in the context of models that possibly account for this trend, including the nature of the central engine, the evolution of progenitor properties as a function of redshift, and incompleteness in current gamma-ray burst samples.

Mirabal, N.↗
NASA NTRS2008

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA is planning a successor to the Hubble Space Telescope designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, Dr. Gardner will discuss the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with Hubble through to the present day. He will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope. Webb is scheduled to launch in 2013, and is designed to find the first galaxies that formed in the distant past and to penetrate the dusty clouds of gas where stars are still forming today. He will compare Webb to Hubble, and discuss recent progress in the construction of the observatory.

Gardner, Jonathan P.↗
NASA NTRS2007

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA is planning a successor to the Hubble Space Telescope designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, Dr. Gardner will discuss the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with Hubble through to the present day. He will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope. Webb is scheduled to launch in 201 3, and is designed to find the first galaxies that formed in the distant past and to penetrate the dusty clouds of gas where stars are still forming today. He will compare Webb to Hubble, and discuss recent progress in the construction of the observatory.

Gardner, Jonathan P.↗
NASA NTRS2008

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA is planning a successor to the Hubble Space Telescope designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, Dr. Gardner will discuss the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with Hubble through to the present day. He will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope. Webb is scheduled to launch in 2013, and is designed to find the first galaxies that formed in the distant past and to penetrate the dusty clouds of gas where stars are still forming today. He will compare Webb to Hubble, and discuss recent progress in the construction of the observatory.

Gardner, Jonathan↗
NASA NTRS2009

A Direct Path to Finding Earth-Like Planets

As envisaged by the 2000 astrophysics decadal survey panel: The main goal of Terrestrial Planet Finder (TPF) is nothing less than to search for evidence of life on terrestrial planets around nearby stars . Here, we consider how an optical telescope paired with a free-flying occulter blocking light from the star can reach this goal directly, without knowledge of results from prior astrometric, doppler, or transit exoplanet observations. Using design reference missions and other simulations, we explore the potential of TPF-O to find planets in the habitable zone around their central stars, to spectrally characterize the atmospheres of detected planets, and to obtain rudimentary information about their orbits. We emphasize the importance of ozone absorption in the UV spectrum of a planet as a marker of photosynthesis by plants, algae, and cyanobacteria.

Heap, Sara R.↗
NASA NTRS2003

cWINNOWER Algorithm for Finding Fuzzy DNA Motifs

The cWINNOWER algorithm detects fuzzy motifs in DNA sequences rich in protein-binding signals. A signal is defined as any short nucleotide pattern having up to d mutations differing from a motif of length l. The algorithm finds such motifs if multiple mutated copies of the motif (i.e., the signals) are present in the DNA sequence in sufficient abundance. The cWINNOWER algorithm substantially improves the sensitivity of the winnower method of Pevzner and Sze by imposing a consensus constraint, enabling it to detect much weaker signals. We studied the minimum number of detectable motifs qc as a function of sequence length N for random sequences. We found that qc increases linearly with N for a fast version of the algorithm based on counting three-member sub-cliques. Imposing consensus constraints reduces qc, by a factor of three in this case, which makes the algorithm dramatically more sensitive. Our most sensitive algorithm, which counts four-member sub-cliques, needs a minimum of only 13 signals to detect motifs in a sequence of length N = 12000 for (l,d) = (15,4).

Liang, Shoudan↗
NASA NTRS2009

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA is planning a successor to the Hubble Space Telescope designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, Dr. Gardner will discuss the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with Hubble through to the present day. He will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope. Webb is scheduled to launch in 2014, and is designed to find the first galaxies that formed in the distant past and to penetrate the dusty clouds of gas where stars are still forming today. He will compare Webb to Hubble, and discuss recent progress in the construction of the observatory.

Gardner, Jonathan P.↗