Laboratory Experiments on Astrophysical Dust Analogs at NASA/MSFC

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Laser Light Sheet Flow Visualization of the Space Launch System Booster Separation Test

Planar flow visualizations were obtained in a wind tunnel test in the NASA Langley Research Centers Unitary Plan Wind Tunnel using the laser-light-sheet method. This method uses a laser to illuminate fine particles generated in the wind tunnel to visualize flow structures. The test article was designed to simulate the separation of the two solid rocket boosters (SRBs) from the core stage of the NASA Space Launch System (SLS) at Mach 4 using a scale model. The test was run on of the SLS Block 1B Cargo (27005) configuration and the SLS Block 1B Crew (28005) configuration. Planar flow visualization was obtained only on the crew configuration. Air at pressures up to 1500 psi was used to simulate plumes from the booster separation motors (BSMs) located at the nose, and aft skirt of the two boosters. The facility free stream was seeded with water vapor, which condensed and froze into small ice crystals in the tunnel nozzle expansion. A continuous wave green (532 nm) laser sheet was used to illuminate the ice crystals, and the resulting Mie-scattered light was collected with a camera. The resulting images clearly identify shock waves and other flow features including BSM plume shapes. Measurements were acquired for different BSM pressures and booster separation locations

Observations of Metallic Species in Mercury's Exosphere

From observations of the metallic species sodium (Na), potassium (K), and magnesium (Mg) in Mercury's exosphere, we derive implications for source and loss processes. All metallic species observed exhibit a distribution and/or line width characteristic of high to extreme temperature - tens of thousands of degrees K. The temperatures of refractory species, including magnesium and calcium, indicate that the source process for the atoms observed in the tail and near-planet exosphere are consistent with ion sputtering and/or impact vaporization of a molecule with subsequent dissociation into the atomic form. The extended Mg tail is consistent with a surface abundance of 5-8% Mg by number, if 30% of impact-vaporized Mg remains as MgO and half of the impact vapor condenses. Globally, ion sputtering is not a major source of Mg, but locally the sputtered source can be larger than the impact vapor source. We conclude that the Na and K in Mercury's exosphere can be derived from a regolith composition similar to that of Luna 16 soil (or Apollo 17 orange glass), in which the abundance by number is 0.0027 (0.0028) for Na and 0.0006 (0.0045) for K

The magnitude of educational disadvantage amongst indigenous minority groups in Australia.

Indigenous groups are amongst the most disadvantaged minority groups in the developed world. This paper examines the educational disadvantage of indigenous Australians by assessing academic performance at a relatively early age. We find that, by the age of 10, indigenous Australians are substantially behind non-indigenous Australians in academic achievement. Their relative performance deteriorates further over the next 2 years. School and locality do not appear to be important determinants of the indigenous to non-indigenous achievement gap. However, geographic remoteness, indigenous ethnicity and language use at home have a marked influence on educational achievement. A current focus of Australian indigenous policy is to increase school resources. Our results suggest that this will not eliminate indigenous educational disadvantage on its own

Limits to Mercury's Magnesium Exosphere from MESSENGER Second Flyby Observations

The discovery measurements of Mercury's exospheric magnesium, obtained by the MErcury Surface. Space ENvironment, GEochemistry. and Ranging (MESSENGER) probe during its second Mercury flyby, are modeled to constrain the source and loss processes for this neutral species. Fits to a Chamberlain exosphere reveal that at least two source temperatures are required to reconcile the distribution of magnesium measured far from and near the planet: a hot ejection process at the equivalent temperature of several tens of thousands of degrees K, and a competing, cooler source at temperatures as low as 400 K. For the energetic component, our models indicate that the column abundance that can be attributed to sputtering under constant southward interplanetary magnetic field (IMF) conditions is at least a factor of five less than the rate dictated by the measurements, Although highly uncertain, this result suggests that another energetic process, such as the rapid dissociation of exospheric MgO, may be the main source of the distant neutral component. If meteoroid and micrometeoroid impacts eject mainly molecules, the total amount of magnesium at altitudes exceeding approximately 100 km is found to be consistent with predictions by impact vaporization models for molecule lifetimes of no more than two minutes. Though a sharp increase in emission observed near the dawn terminator region can be reproduced if a single meteoroid enhanced the impact vapor at equatorial dawn, it is much more likely that observations in this region, which probe heights increasingly near the surface, indicate a reservoir of volatile Mg being acted upon by lower-energy source processes

Effects of Wolf Removal on Livestock Depredation Recurrence and Wolf Recovery in Montana, Idaho and Wyoming

Wolf predation on livestock and management methods used to mitigate conflicts are highly controversial and scrutinized especially where wolf populations are recovering.  Wolves are commonly removed from a local area in attempts to reduce further depredations, but the effectiveness of such management actions is poorly understood.  We compared the effects of 3 management responses to livestock depredation by wolf packs in Montana, Idaho, and Wyoming:  no removal, partial pack removal, and full pack removal.  From 1989 to 2008, we documented 967 depredations by 156 packs: 228 on sheep and 739 on cattle and other stock.  Median time between recurrent depredations was 19 days following no removal (n = 593), 64 days following partial pack removal (n = 326), and 730 days following full pack removal (n = 48).  Partial pack removal was most effective if conducted within the first 7 days following depredation, after which there was only a marginally significant difference between partial pack removal and no action (HR = 0.86, P = 0.07), and no difference after 14 days (HR = 0.99, P = 0.93).   Ultimately, pack size was the best predictor of a recurrent depredation event; the probability of a depredation event recurring within 5 years increased by 7% for each animal left in the pack after the management response.  However, the greater the number of wolves left in a pack, the higher the likelihood the pack met federal criteria to count as a breeding pair the following year toward population recovery goals

Signal peptide peptidase (SPP) dimer formation as assessed by fluorescence lifetime imaging microscopy (FLIM) in intact cells

BACKGROUND: Signal peptide peptidase (SPP) is an intramembrane cleaving protease identified by its cleavage of several type II membrane signal peptides. Conservation of intramembrane active site residues demonstrates that SPP, SPP family members, and presenilins (PSs) make up a family of intramembrane cleaving proteases. Because SPP appears to function without additional protein cofactors, the study of SPP may provide structural insights into the mechanism of intramembrane proteolysis by this biomedically important family of proteins. Previous studies have shown that SPP isolated from cells appears to be a homodimer, but some evidence exists that in vitro SPP may be active as a monomer. We have conducted additional experiments to determine if SPP exists as a monomer or dimer in vivo. RESULTS: Fluorescence lifetime imaging microscopy (FLIM) can be is used to determine intra- or intermolecular interactions by fluorescently labeling epitopes on one or two different molecules. If the donor and acceptor fluorophores are less than 10 nm apart, the donor fluorophore lifetime shortens proportionally to the distance between the fluorophores. In this study, we used two types of fluorescence energy transfer (FRET) pairs; cyan fluorescent protein (CFP) with yellow fluorescent protein (YFP) or Alexa 488 with Cy3 to differentially label the NH2- or COOH-termini of SPP molecules. A cell based SPP activity assay was used to show that all tagged SPP proteins are proteolytically active. Using FLIM we were able to show that the donor fluorophore lifetime of the CFP tagged SPP construct in living cells significantly decreases when either a NH2- or COOH-terminally YFP tagged SPP construct is co-transfected, indicating close proximity between two different SPP molecules. These data were then confirmed in cell lines stably co-expressing V5- and FLAG-tagged SPP constructs. CONCLUSION: Our FLIM data strongly suggest dimer formation between two separate SPP proteins. Although the tagged SPP constructs are expressed throughout the cell, SPP dimer detection by FLIM is seen predominantly at or near the plasma membrane

Endocrine Effects of Inhaled Corticosteroids in Children

Inhaled corticosteroids (ICSs) are widely used as first-line treatment for various chronic respiratory illnesses. Advances in devices and formulations have reduced their local adverse effects. However, as delivery of ICSs to the lungs improves, the systemic absorption increases, and an adverse effect profile similar to, although milder than, oral corticosteroids has emerged. The most serious potential adverse effect is adrenal insufficiency, which can be life threatening. Adrenal insufficiency occurs most in patients taking the highest doses of ICSs but is reported with moderate or even low doses as well. Our recommendations include greater vigilance in testing adrenal function than current standard practice. In patients with diabetes mellitus (types 1 and 2), an increase in glucose levels is likely, and diabetes medication adjustment may be needed when initiating or increasing ICSs. The risk of linear growth attenuation and adverse effects on bone mineral density is generally low but should be considered in the face of additional risk factors. On behalf of the Pediatric Endocrine Society Drugs and Therapeutics Committee, we present a review of the endocrine adverse effects of ICSs in children and offer recommendations relating to testing and referral. Limited data in particular realms diminish the strength of certain recommendations, and clinical judgment continues to be paramount

Mercury's Exosphere During MESSENGER's Second Flyby: Detection of Magnesium and Distinct Distributions of Neutral Species

During MESSENGER's second Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer observed emission from Mercury's neutral exosphere. These observations include the first detection of emission from magnesium. Differing spatial distributions for sodium, calcium, and magnesium were revealed by observations beginning in Mercury's tail region, approximately 8 Mercury radii anti-sunward of the planet, continuing past the nightside, and ending near the dawn terminator. Analysis of these observations, supplemented by observations during the first Mercury flyby as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes