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Experiments are described in which monolithic glasses, short fibers, and glass ceramics were prepared by melt processing of simulated lunar regolith. The melt was formed by direct solar as well as resistive heating and was processed using a range of techniques. The processes used in making the three types of lunar ceramics are described together with physical properties of these ceramics and their potential uses.
Recent results of radio observations of the solar and stellar coronae are reviewed. Attention is given to the results obtained on quiet-sun fine structures; the active region observations, with particular consideration given to the soft X-ray and radio comparisons of observations made during the Coronal Magnetic Structures Observing Campaign and the strength of the magnetic fields in the corona; the radio observations of solar flares; and the radio observations of stellar coronae of the RS Canum Venaticorum binaries, M dwarf stars, pre-main-sequence stars, and chemically-peculiar B stars. Also discussed are current issues in stellar radiophysics and perspectives in solar radio physics.
Ferritin is a well-known iron-storage protein, and is a spherical shell that consists of 24 identical subunits packed in a 432 symmetry. The typically large protein size and its distinction from lysozyme as to chemical and physical characteristics make ferritin an attractive model protein for crystal growth and perfection investigation-as an alternative to the most widely studied lysozyme. In this contribution, the latest results obtained from coherence-based x-ray diffraction imaging and diffraction experiments will be presented on octahedral apoferritin (a demetalized form of ferritin) crystals grown from various growth conditions. Crystal specimens, which have the measured rocking-curve widths varying from a few arcseconds to several tens arcseconds (or more), are comparatively examined by intrinsically highly sensitive mapping of lattice perfection and defects. The richness of the observed defects and growth features offers insight into perfection and growth of protein crystals. Beautiful interference fringe patterns formed in diffraction images and fine oscillation structure of rocking curves observed will be discussed for understanding of physical origins and the underlying impact.
In a wind tunnel facility, the direct measurement of forces and moments induced on the model are performed by a force measurement balance. The measurement balance is a precision-machined device that has strain gages at strategic locations to measure the strain (i.e., deformations) due to applied forces and moments. The strain gages convert the strain (and hence the applied force) to an electrical voltage that is measured by external instruments. To address the problem of thermal gradients on the force measurement balance NASA-LaRC has initiated a research program called TIGER - Thermally-Induced Gradients Effects Research. The ultimate goals of the TIGER program are to: (a) understand the physics of the thermally-induced strain and its subsequent impact on load measurements and (b) develop a robust thermal gradient compensation technique. This paper will discuss the impact of thermal gradients on force measurement balances, specific aspects of the TIGER program (the design of a special-purpose balance, data acquisition and data analysis challenges), and give an overall summary.
Studies of the morphology and radar properties of volcanic deposits can aid in understanding their differences and formation. On Venus, volcanoes range in size from large highland edifices, such as Theia Mons, to small shields and domes which are often found in groups of tens to hundreds. In plains regions, windstreaks are sometimes found near shield fields, suggesting that there may be fine grained deposits associated with the volcanoes. Previous studies of Bell Regio suggest the presence of fine-grained material in a low dielectric constant triangular shaped region on the flank of Tepev Mons, which may be crater ejecta or a pyroclastic deposit spread westward by wind. The eastern caldera on Tepev Mons shows a steep trend in backscattered power with incidence angle and has high RMS-slopes, implying a finegrained covering such as ash. Radar waves can easily penetrate smooth mantling layers such as ash and aeolian deposits. If a radar system can measure two orthogonal polarizations, it is possible to detect subsurface scattering and infer the presence of surficial deposits. The Magellan spacecraft could only measure one polarization and was therefore not able to fully characterize the polarization state of the radar echoes. We compare Arecibo dual-polarization data for Venus to Magellan images and emissivity data to investigate the physical properties of volcanic deposits.
The San Joaquin Valley (SJV) suffers from severe health-endangering episodes of PM2.5 aerosol loadings in wintertime; episodes last approximately 5 days and differ in geographical distribution and composition. PM2.5 stations are scattered; consequently the use of remote sensing to map variable regional patterns of these varying respirable aerosol concentrations is desirable. High-precision AOT retrievals can capture column particulate loading. However,PM2.5 mapping is challenging due to several reasons: particularly thin mixed layers (ML) and thus relatively low aerosol optical thickness (AOT) close to current measurement limits, variable and a typical composition of the aerosols, and complex surface bidirectional reflectance. However, the West does present some advantages in analysis. Air basins are isolated from long-distance transport, and experience predominant strong meteorological subsidence. Thus these Western basin regions have fewer problematic cases of overriding aerosol layers detached from the surface. To counter such local overriding, Chu et al. have described an approach for the Eastern US, and He et al have described a synoptic classification approach useful in Shanghai. The Bay Area Air Quality Management District (BAAQMD) expands our experience with the use of AOT, with lower PM2.5 and several isolated sub-basins. We have prepared daily maps of episodes in each region. We present also a sequence of increasingly detailed statistical models, AOT initially appears to contribute little information; however, inclusion of weather information reveals its utility. Lyapustin and Wang's MultiAngle Implementation of Atmospheric Correction (MAIAC) retrieval for AOT provided the most useful operational remote sensing information for these regions. It provides high (1-km) spatial resolution maps and a high percentage of availability. Empirical regression methods have found that random effects regression models (aka mixed effects models, ME) employing AOT provide good estimates of ground PM2.5 concentrations.Here, we attempt to extend these methods and evaluate the usefulness of AOT with greater physical analysis, based on DISCOVER-AQ4 experience.
The structure and function of coral reef ecosystems is increasingly compromised by multiple stressors, even in the most remote locations. Severe, acute disturbances such as volcanic eruptions represent extreme events that can annihilate entire reef ecosystems, but also provide unique opportunities to examine ecosystem resilience and recovery. Here, we examine the destruction, persistence and initial recovery of reefs associated with the hydromagmatic eruption that created Earth’s newest landmass, the Hunga Tonga–Hunga Ha’apai volcanic island. Despite extreme conditions associated with the eruption, impacts on nearby reefs were spatially variable. Importantly, even heavily affected reefs showed signs of rapid recovery driven by high recruitment, likely from local refuges. The remote location and corresponding lack of additional stressors likely contribute to the resilience of Hunga’s reefs, suggesting that in the absence of chronic anthropogenic stressors, coral reefs can be resilient to one of the largest physical disturbances on Earth.
This study examined the role of ethnicity on the aerobic fitness, blood pressure, and selected blood chemistry values of women. One hundred twenty-four females (mean age 41.37 +/- 9.0) were medically Examined at the NASA/Johnson Space Center occupational health clinic. Ethnic groups consisted of 23 Black (B), 18 Hispanic (H) and 83 Non-minority (NM). Each woman had a maximum Bruce treadmill stress test (RER greater than or = 1.1) and a negative ECG. Indirect calorimetry, skinfolds, self-report physical activity (NASA activity scale), seated blood pressure, and blood chemistry panel determined VO2max, percent fat, level of physical activity, blood pressure and blood chemistry values. ANOVA revealed that the groups did not differ (p greater than 0.05) in age, VO2 max, weight, percent fat, level of physical activity, total cholesterol, or HDL-C. However, significant differences (p greater than 0.05) were noted in BMI, diastolic blood pressure, and blood chemistries. BMI was 3.17 higher in H than in NM; resting diastolic pressures were 5.69 and 8.05 mmHg. lower in NM and H than in B; triglycerides were 48.07 and 37.21 mg/dl higher in H than in B and NM; hemoglobin was .814 gm/dl higher in NM than B; fasting blood sugar was 15.41 mg/dl higher in H than NM; The results of this study showed that ethnic groups differed in blood pressure and blood chemistry values but not aerobic fitness or physical activity. There was an ethnic difference in BMI but not percent fat.
Chemical kinetics analysis of Mars atmosphere composition and physical properties
This talk deals with collision processes of the following kind: (a) an ionizing collision of an electron with a neutral atom, (b) a photon incident of a negative ion resulting in two-electron ejection. In both cases the final state is a positive ion and two outgoing electrons, and in principle both processes should be governed by the same form of threshold law. It is generally conceded that this is one of the most difficult basic problems in nonrelativistic quantum mechanics. The standard treatment (due to Wannier) will be briefly reviewed in terms of the derivation of his well- known threshold law for the yield (Q) of positive ions vs. the excess energy (E): Q(sub w) varies as E(exp 1.127...). The derivation is a brilliant analysis based on Newton's equations, leading to the dominance of events in which the two electrons emerge on opposite sides of the residual ion with similar energies. In contrast, I will argue on the basis of quantum mechanical ideas that in the threshold limit the more likely outcome are events in which the electrons emerge with decidedly different energies, leading to a formally different (Coulomb-dipole) threshold law Q(sub CD) varies as E(1 + C sin(alpha ln(E)+mu)]/[ln(E)](exp 2). Additional aspects of that approach will be discussed . Some: experimental results will be presented, and more incisive predictions involving polarized projectiles and targets will be given.
EUNIS (Extreme Ultraviolet Normal Incidence Spectrograph) is a high-efficiency extreme ultraviolet spectrometer that is expected to fly for the first time in 2004 as a sounding rocket payload. Using two independent optical systems, EUNIS will probe the structure and dynamics of the inner solar corona high spectral resolution in two wavelength regions: 17-21 nm with 3.5 pm resolution and 30-37 nm with 7 pm resolution. The long wavelength channel includes He II 30.4 nm and strong lines from Fe XI-XVI; the short wavelength channel includes strong lines of Fe IX-XIII. Angular resolution of 2 arcsec is maintained along a slit covering a full solar radius. EUNIS will have 100 times the throughput of the highly successful SERTS payloads that have preceded it. There are only two reflections in each optical channel, from the superpolished, off-axis paraboloidal primary and the toroidal grating. Each optical element is coated with a high-efficiency multilayer coating optimized for its spectral bandpass. The detector in each channel is a microchannel plate image intensifier fiber- coupled to three 1K x 1K active pixel sensors. EUNIS will obtain spectra with a cadence as short as 1 sec, allowing unprecedented studies of the physical properties of evolving and transient structures. Diagnostics of wave heating and reconnection wil be studied at heights above 2 solar radii, in the wind acceleration region. The broad spectral coverage and high spectral resolution will provide superior temperature and density diagnostics and will enable underflight calibration of several orbital instruments, including SOHO/CDS and EIT, TRACE, Solar-B/EIS, and STEREO/EUVI. EUNIS is supported by NASA through the Low Cost Access to Space Program in Solar and Heliospheric Physics.
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The NASA Solar Dynamics Observatory (SDO), scheduled for launch in early 2010, incorporates a suite of instruments including the Extreme Ultraviolet Variability Experiment (EVE). EVE has multiple instruments including the Multiple Extreme ultraviolet Grating Spectrographs (MEGS) A, B, and P instruments, the Solar Aspect Monitor (SAM), and the Extreme ultraviolet SpectroPhotometer (ESP). The radiometric calibration of EVE, necessary to convert the instrument counts to physical units, was performed at the National Institute of Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility (SURF III) located in Gaithersburg, Maryland. This paper presents the results and derived accuracy of this radiometric calibration for the MEGS A, B, P, and SAM instruments, while the calibration of the ESP instrument is addressed by Didkovsky et al. . In addition, solar measurements that were taken on 14 April 2008, during the NASA 36.240 sounding-rocket flight, are shown for the prototype EVE instruments.
Laser interferometry and photon scattering in high temperature plasma diagnostics
Flame structure of hydrazine burning in oxidizing atmosphere determined by measuring temperature and specific contractions at 90 degrees from stagnation point
Excited nuclei electromagnetic de-excitation rate by inelastic scattering in stellar particles calculated as function of temperature, density, transition energy and multipole functions