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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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This invention provides sealed access to the interior of a pressure vessel and consists of a tube. a collar, redundant seals, and a port. The port allows the seals to be pressurized and seated before the pressure vessel becomes pressurized.
Optimal extraction of pulses of constant known shape from a time series with stationary noise is well understood and widely used in detection applications. Applications where high resolution is required over a wide range of input signal amplitudes use much of the dynamic range of the sensor. The noise will in general vary over this signal range, and the response may be a nonlinear function of the energy input. We present an optimal least squares procedure for inferring input energy in such a detector with nonstationary noise and nonlinear energy response.
ASCA (Advanced Satellite for Cosmology and Astrophysics) and EUVE (Extreme Ultraviolet Explorer) spectra of active late-type stars imply that Fe and other medium-Z elements may be 2-10 times less abundant in the coronae of these stars than in their photo-spheres (the MAD effect). These deficiencies may be related to the solar FIP (First Ionization Potential) effect, in which Fe and other low First Ionization Potential elements appear enriched in the solar corona over their photospheric values. The FIP effect is time variable. As part of this proposal, the K0-2 III star, 29 Draconis, was observed in X rays with the ASCA spacecraft in order to measure the coronal abundances of this star at three different stellar longitudes over its 31-day rotation cycle. The goal of the observations was to learn whether coronal abundances, and hence coronal magnetic structure, vary across the surface of 29 Draconis in phase with the motion of dark star-spots across its disk. A second task included in this project was a systematic reanalysis of 18-20 deep exposures of active coronal stars, which were extracted from the ASCA public archives. New thermal models were computed for each spectrum in order to derive coronal metal abundances for each star. The goal of this survey was to search for possible trends in coronal abundance with various stellar parameters such as rotation, chromospheric activity levels at ultraviolet and optical wavelengths, or evolutionary stage.
This paper investigates the suitability of the equation for accurately defining solar cell parameter degradation as a function of hard particle radiation. Y = Y/sub o/ + C/sub 1/ * Log(1 + /spl phi///spl phi//sub x/) + C/sub 2/ * Log(1 + /spl phi///spl phi//sub y/) The paper also provides methods for determining the constants in the equation and compares results from this equation to those obtained by the more traditionally used. Y = /spl Sigma/(a/sub i/ * [In(/spl phi/)]/sup i/)
We present observations and an interpretation of a unique multiple-turn spiral flux tube eruption from AR10030 on 2002 July 15. The TRACE CIV observations clearly show a flux tube that is helical and that is erupting from within a sheared magnetic field. These observations are interpreted in the context of the breakout model for magnetic field explosions. The initiation of the helix eruption starts 25 seconds after the peak of the flare s strongest impulsive spike of microwave gryosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double CME. The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection heats the two-ribbon flare and might or might not produce the helix. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong magnetic shear in the region is associated with rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field magnetic inversion line within a filament channel, and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation. However, the observations are compatible with internal reconnection in a sheared magnetic arcade in the formation and eruption of the helix.
The concept of "Intermittency" was introduced by Bialas and Peschanski to try to explain the "large" fluctuations of multiplicity in restricted intervals of rapidity or pseudorapidity. A formalism was proposed to to study non-statistical (more precisely, non-Poisson) fluctuations as a function of the size of rapidity interval, and it was further suggested that the "spikes" in the rapidity fluctuations were evidence of fractal or intermittent behavior, in analogy to turbulence in fluid dynamics which is characterized by self-similar fluctuations at all scales-the absence of well defined scale of length.
We present observations and an interpretation of a unique multiple-turn spiral flux tube eruption from active region 10030 on 2002 July 15. The TRACE C IV observations clearly show a flux tube that is helical and erupting from within a sheared magnetic field. These observations are interpreted in the context of the breakout model for magnetic field explosions. The initiation of the helix eruption. as determined by a linear backward extrapolation, starts 25 s after the peak of the flare's strongest impulsive spike of microwave gyrosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double coronal mass ejection (CME). The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection releases the helix and heats the two-ribbon flare. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong magnetic shear in the region is compatible with the observed rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field magnetic inversion line within a filament channel. and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation.
Substantial death of migrating and differentiating neurons occurs within the developing CNS of mice that are deficient in genes required for repair of double-stranded DNA breaks. These findings suggest that large-scale, yet previously unrecognized, double-stranded DNA breaks occur normally in early postmitotic and differentiating neurons. Moreover, they imply that cell death occurs if the breaks are not repaired. The cause and natural function of such breaks remains a mystery; however, their occurrence has significant implications. They might be detected by histological methods that are sensitive to DNA fragmentation and mistakenly interpreted to indicate cell death when no relationship exists. In a broader context, there is now renewed speculation that DNA recombination might be occurring during neuronal development, similar to DNA recombination in developing lymphocytes. If this is true, the target gene(s) of recombination and their significance remain to be determined.
A chart review covering the first 5 years of clinical experience with a combined dietary and exercise intervention program for the reduction of hypercholesterolemia at the National Aeronautics and Space Administration headquarters demonstrated the program's success in maintaining high-density lipoprotein cholesterol (HDL-C) levels while significantly lowering total serum cholesterol levels. This combined program also resulted in improved ratios of total serum cholesterol to HDL-C and lowered levels of low-density lipoprotein cholesterol, thus further reducing the risk for cardiovascular disease. The National Aeronautics and Space Administration Cardiovascular Risk Reduction Program was developed after it was determined that although dietary intervention alone improved total cholesterol levels, it often resulted in a more than proportionate decrease in HDL-C and a worsening of the ratio of cholesterol to HDL-C. An approach was needed that would positively affect all factors of the lipid profile. The findings from the program indicate that reduction of cardiovascular risk can be accomplished easily and effectively at the worksite through dietary intervention, personal monitoring, and a reasonable exercise program.
Titan is the only satellite in our Solar System with a substantial atmosphere, the origins and evolution of which are still not well understood. Its primary (greater than 90%) component is nitrogen, with a few percent methane and lesser amounts of other species. Methane and ethane are stable in the liquid state under the temperature and pressure conditions in Titan s lower atmosphere and at the surface; indeed, clouds, likely composed of methane, have been detected. Photochemical processes acting in the atmosphere convert methane into more complex hydrocarbons, creating Titan s haze and destroying methane over relatively short timescales. Therefore, it has been hypothesized that Titan s surface has reservoirs of liquid methane which serve to resupply the atmosphere. Early observations of Titan s surface revealed albedo patterns which have been interpreted as dark hydrocarbon liquids occupying topographically low regions between higher-standing exposures of bright, water-ice bedrock, although this is far from being the only explanation for the observed albedo contrast. Observations made by the Imaging Science Subsystem during Cassini's approach to Saturn and its first encounters with Titan show the bright and dark regions in greater detail but have yet to resolve the question of whether there are liquids on the surface.
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In this paper, the metrology pointing sensor of the Starlight ground instrument prototype is characterized and a siderostat pointing control loop is closed between two optical benches with a 10 meter separation.
The Near Infrared Mapping Spectrometer (NIMS) has obtained spectra of volcanoes on the surface of the jovian satellite Io.
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Explore the source record for details and available documents.
Quantum mechanical simulations of carrier transport in Si require an accurate model of the complicated Si bandstructure. Tight-binding models are an attractive method of choice since they bear the full electronic structure symmetry in them and they can discretize a realistic device on an atomic scale.
This paper describes a new algorithmic paradigm for solving problems where a model is extracted from or it to data. This paradigm has numerous applications, particularly in computer vision.