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NASA NTRS2006

Feldspathic Clasts in Yamato 86032: Remnants of the Lunar Crust with Implications for its Formation and Impact History

Yamato (Y)-86032 is a relatively large, feldspathic lunar highlands meteorite composed of a variety of highland lithologies. Low bulk contents of Th and Fe indicated that it came from a region of the moon far distant from the Procellarum KREEP Terrain (PKT) and the Apollo landing sites, perhaps from the farside. A large (5.2 x 3.6 cm) slab was cut from Y-86032 . We report results from coordinated textural, mineralogical-petrological, chemical, and isotopic studies of lithologies identified in the slab, emphasizing the results of Ar-39/Ar-40, Rb-Sr, and Sm-Nd chronological studies as well as Sm-isotopic studies. These studies characterize the history of Y-86032 and its precursors in the farside mega-regolith, leading to inferences about the formation and evolution of the lunar crust. Textural studies establish that the Y-86032 breccia is composed of a variety of highland components including feldspathic breccias, and other components, such as possible VLT mare basalts. Impact melt veins smoothly abut the other lithologies. Thus, Y-86032 experienced at least two impact events. These impacts occurred on a predominantly feldspathic protolith, which formed 4.43+/-0.03 Ga ago as determined from a Sm-Nd isochron for mineral clasts separated from the two dominant lithologies. Initial Nd-143/Nd-144 in the protolith at that time was -0.64+/-0.13 epsilon-units below Nd-143/Nd-144 in reservoirs having chondritic Sm/Nd ratios, consistent with prior fractionation of mafic cumulates from the LMO. Although the mineral chemistry of these clasts differs in detail from that of minerals in Apollo 16 Ferroan Anorthosites (FANs), the Rb-Sr studies establish that the initial Sr-87/Sr-86 in them was the same as in the FANs.

Nyquist, L.↗
NASA NTRS2006

The Alpha Particle X-Ray Spectrometer (APXS): Results from Gusev Crater and Calibration Report

The chemical composition of rocks and soils on Mars analyzed during the Mars Exploration Rover Spirit Mission was determined by X-ray analyses with the Alpha Particle X-Ray Spectrometer (APXS). Details of the data analysis method and the instrument calibration are presented. Measurements performed on Mars to address geometry effects and background contributions are shown. Cross calibration measurements among several instrument sensors and sources are discussed. An unintentional swap of the two flight instruments is evaluated. New concentration data acquired during the first 470 sols of rover Spirit in Gusev Crater are presented. There are two geological regions, the Gusev plains and the Columbia Hills. The plains contain soils that are very similar to previous landing sites on Mars. A meteoritic component in the soil is identified. Rocks in the plains revealed thin weathering rinds. The underlying abraded rock was classified as primitive basalt. One of these rocks contained significant Br that is probably associated with vein-filling material of different composition. One of the trenches showed large subsurface enrichments of Mg, S, and Br. Disturbed soils and rocks in the Columbia Hills revealed different elemental compositions. These rocks are significantly weathered and enriched in mobile elements, such as P, S, Cl, or Br. Even abraded rock surfaces have high Br concentrations. Thus, in contrast to the rocks and soils in the Gusev Plains, the Columbia Hills material shows more significant evidence of ancient aqueous alteration.

Gellert, R.↗
NASA NTRS2006

Opaque Assemblages in CK and CV Carbonaceous Chondrites

CK carbonaceous chondrites are the only group of carbonaceous chondrites that exhibit thermal metamorphism. As a result, CKs display features of metamorphism such as silicate darkening, recrystallization and shock veins. Calcium Aluminum Inclusions and Fe-Ni metal are rare. CV carbonaceous chondrites are unequilibrated and have two subgroups; oxidized and reduced. The CV and CK carbonaceous chondrite groups have been compared to each other often because of petrographic similarities, such as overlapping oxygen isotopic ratios. Scientists have suggested the two groups of carbonaceous chondrites formed from the same parent body and CKs are equilibrated CV chondrites [1, 2]. The oxidized CV group has been most closely related to CKs. This study examines the petrology and mineralogy of CKs and CVs focusing on opaque minerals found in the meteorites. Using the oxide, metal and sulfide assemblages, constraints can be placed on the temperature and oxygen fugacity at which the meteorites equilibrated. The temperature and oxygen fugacity of the CK and CV chondrites can be compared in order to help define their formation history.

Neff, K. E.↗
NASA NTRS2008

The Lunar X-ray Observatory (LXO)

X-ray emission from charge exchange recombination between the highly ionized solar wind and neutral material i n Earth's magnetosheath has complicated x-ray observations of celestial objects with x-ray observatories including ROSAT, Chandra, XMM-Newton, and Suzaku. However, the charge-exchange emission can also be used as an important diagnostic of the solar-wind interacting with the magnetosheath. Soft x-ray observations from low-earth orbit or even the highly eccentric orbits of Chandra and XMM-Newton are likely superpositions of the celestial object of interest, the true extra-solar soft x-ray background, geospheric charge exchange, and heliospheric charge exchange. We show that with a small x-ray telescope placed either on the moon, in a similar vein as the Apollo ALSOP instruments, or at a stable orbit near L1, we can begin t o disentangle the complicated emission structure in the soft x-ray band. Here we present initial results of a feasibility study recently funded by NASA t o place a small x-ray telescope on the lunar surface. The telescope operates during lunar night to observe charge exchange interactions between the solar wind and magnetospheric neutrals, between the solar wind and the lunar atmosphere, and an unobstructed view of the soft x-ray background without the geospheric component.

Porter, F. Scott↗
NASA NTRS1993

Patent Foramen Ovale: Is Stroke Due to Paradoxical Embolism?

Background and Purpose: A patent foramen ovale has been reported to be significantly more frequent in young stroke patients than in matched control subjects, and paradoxical embolism has been suggested as the main mechanism of stroke in-this situation. The present study was designed to test this hypothesis. Methods: Sixty-eight consecutive patients under 55 years of age presenting with an ischemic stroke had an extensive workup, including transesophageal echocardiography with contrast. We compared the prevalence of criteria for the diagnosis of paradoxical embolism in patients with and without a patent foramen ovale. Results: A patent foramen ovale was found in 32 patients (47%). A Valsalva-provoking activity was present at stroke onset in six patients with a patent foramen ovale and in eight patients with no patent foramen ovale (X(sup 2)=0.1, nonsignificant). Clinical/radiological features suggestive of an embolic mechanism were not more frequent in patients with a patent foramen ovale. Clinical evidence of deep vein thrombosis was present in one patient with a patent foramen ovale and in none of the others. No occult venous thrombosis was found in a subgroup of patients with a patent foramen ovale and no definite cause for stroke who underwent venography (n=13). Conclusions. Our results do not support the hypothesis that paradoxical embolism is the primary mechanism of stroke in patients with a patent foramen ovale. (Stroke 1993;24:31-34) KEY WORDS e cerebral ischemia e embolism foramen ovale, patent

Ranoux, D.↗
NASA NTRS2009

Can a Satellite-Derived Estimate of the Fraction of PAR Absorbed by Chlorophyll (FAPAR(sub chl)) Improve Predictions of Light-Use Efficiency and Ecosystem Photosynthesis for a Boreal Aspen Forest?

Gross primary production (GPP) is a key terrestrial ecophysiological process that links atmospheric composition and vegetation processes. Study of GPP is important to global carbon cycles and global warming. One of the most important of these processes, plant photosynthesis, requires solar radiation in the 0.4-0.7 micron range (also known as photosynthetically active radiation or PAR), water, carbon dioxide (CO2), and nutrients. A vegetation canopy is composed primarily of photosynthetically active vegetation (PAV) and non-photosynthetic vegetation (NPV; e.g., senescent foliage, branches and stems). A green leaf is composed of chlorophyll and various proportions of nonphotosynthetic components (e.g., other pigments in the leaf, primary/secondary/tertiary veins, and cell walls). The fraction of PAR absorbed by whole vegetation canopy (FAPAR(sub canopy)) has been widely used in satellite-based Production Efficiency Models to estimate GPP (as a product of FAPAR(sub canopy)x PAR x LUE(sub canopy), where LUE(sub canopy) is light use efficiency at canopy level). However, only the PAR absorbed by chlorophyll (a product of FAPAR(sub chl) x PAR) is used for photosynthesis. Therefore, remote sensing driven biogeochemical models that use FAPAR(sub chl) in estimating GPP (as a product of FAPAR(sub chl x PAR x LUE(sub chl) are more likely to be consistent with plant photosynthesis processes.

Zhang, Qingyuan↗
NASA NTRS2009

Acute Hemodynamic Effects of the Braslet-M Device on the International Space Station

The Braslet-M occlusion device is prescribed for cosmonauts as a countermeasure for early phases of spaceflight to temporarily alleviate symptoms associated with the cephalad fluid shift. Using a multipurpose ultrasound (US) device onboard, we assessed the acute hemodynamic effects of the Bracelet-M device on a long duration International Space Station (ISS) crewmember. Methods A combination of just-in-time training and real-time remote expert assistance was used to conduct the imaging procedures. An HDI-5000 imager (Philips, Bothell, WA) was used, provided by the ISS Human Research Facility. Superficial femoral artery (SFA), femoral vein (FV) flow spectra were obtained at mid-thigh level. Left ventricle was imaged through the apical 4-chamber view, with Color M-Mode to measure propagation velocity (V (p)). After 10 minutes of Bracelet-M use, data collection was repeated. All data were transmitted in DICOM format to ground for analysis. Results With Braslet-M, cardiac V(p) slope decreased (56ms to 42ms). A stagnation signature in the FV was seen suggesting impeded flow (rouleaux formation, too-low-to-measure velocity, and increase in diameter). Quadri-phasic flow in SFA was seen both before and after Braslet-M application. Velocities in the SFA decreased with Braslet-M (65cm/sec to 52cm/sec) and so did the time velocity integrals (16.97 to 12.4); the flow pattern spoke of resistivity increase in the vascular bed. Conclusion In the long duration ISS crewmember we observed effects of lower extremity venous occlusion through both central and peripheral indicators. A part of circulating volume transferred to peripheral potential vascular space. Impediment to venous outflow was demonstrated objectively, with a commensurate change in the flow pattern of the main feeding artery. Central volume reduction caused lower V(p). Additional studies are warranted to determine the time course of the changes and the dynamics in interstitial fluid sequestration, as well as the safe levels and duration of the compression forces.

Hamilton, Douglas R.↗
NASA NTRS2010

Jarosite in the Shergottite Que 94201

Veins of the hydroxylated, potassium ferric sulfate mineral jarosite - KFe3(SO4)2(OH)6 - have been identified in the martian meteorite Queen Alexandra Range (QUE) 94201. Iron potassium sulfate had been reported in QUE 94201 by Wentworth and Gooding. Jarosite has been reported in other Martian meteorites - Roberts Massif (RBT) 04262, Miller Range (MIL) 03346, and Yamato 000593 - and it has been identified on the Martian surface by Moessbauer spectroscopy. Given the presence of jarosite on Mars, and the burgeoning interest in water-rock interactions on Mars, the question arises whether jarosite in Martian meteorites is formed by aqueous alteration on Mars, or in Antarctica. Hydrogen isotopes are potentially sensitive indicators of the site of formation or last equilibration of hydrous alteration minerals, because of the large difference between D/H ratio of the Martian atmosphere (and also presumably the cryosphere) and terrestrial hydrogen. The Martian atmospheric delta D(sub SMOW) ratio is approximately +4200%o, igneous minerals with substantial hydrogen (phosphates) have high D, ~ +2000%o to +4700%o versus terrestrial waters with approximately 480%o to +130%o. The crystal chemistry and structure of jarosite are reviewed in Papi ke et al. Here we report hydrogen isotopes measured in jarosite in QUE 94201 by ion microprobe, and also report on the major element composition of jarosite measured by electron microprobe.

Ross, D. K.↗
NASA NTRS2010

39Ar - 40Ar Studies of Lherzolitic Shergottites Yamato 000097 and 984028

Yamato 984028 (Y984028) was discovered by the Japanese Antarctic Research Expedition (JARE) in 1998 and recently classified as a lherzolitic shergottite with large pyroxene oikocrysts enclosing rounded olivine and chromites. It also contains shock veining and maskelynite. Y984028 is paired with the more recent lherzolitic shergottite finds Y000027/47/97 based on similarities in mineralogy and chemistry, as well as isotopic composition. We present here the studied Ar-39-Ar-40 of Y-984028 whole rock (WR) and pyroxene (Px), in order to gain better understanding of trapped Ar components with a comparison of the possibly-paired Y000097 Ar release.

Park, J.↗
NASA NTRS2001

Combining Information on Multiple Detection Techniques to Estimate the Effect of Patent Foramen Ovale on Susceptibility to Decompression Illness

The assembly and the maintenance of the International Space Station is expected to require hundreds of extravehicular excursions (EVA's) in the next 10 years. During an EVA, in order to allow movement and bending of limbs, spacesuit pressures are reduced to about 4.3 psi. as compared with about 14.7 psi. for normal atmospheric pressure at sea level. However, the exposure of astronauts to reduced pressures in spacesuits, is conducive to fonnation and growth of gas bubbles within venous blood or tissues, which could cause decompression illness (DCI), a pathology best known to occur among deep-sea divers when they return to the surface. To reduce the risk of DCI, astronauts adjust to the reduced pressure in stages for a prolonged time known as a "pre-breathe" period prior to their extravehicular activity. Despite the use of pre-breathe protocols, an increased risk of DCI can arise for about 25% of humans who have a small hole, known as a patent foramen ovale (PFO), between two chambers of the heart. The atrial septum's fossa oval is, an embryological remnant of a flap between the septae primum and secundum allows fetal right atrial blood to pass into the left atrium, and usually closes after birth (Hagen, et al,. 1984). If fusion does not occur, a valve-like opening, the foramen ovale persists between the two atria. It has been suggested that astronauts with PFO's might be at greater risk of stroke or other serious neurological DCI because bubbles from a venous site may traverse a PFO, travel to the aorta and then enter the cerebral circulatory system causing a stroke (Figure 1). Astronauts are not now screened for PFO's, however consideration is being given to doing so. Here, we study three main methods abbreviated here as "ITE", "TCD" and "TEE", for detecting PFO's in living subjects. All involve the introduction of bubbles into a vein, immediately after which a sensory probe attempts to detect the bubbles in systemic circulation. Presence of the injected bubbles in the systemic circulation is indicative of a PFO. More detailed descriptions are given after the explanation of PFO's under Figure I. Even if a true PFO affects the risk of DCI, there remains a question of how effective screening would be if the detection method has errors of omission and/or commission. Of the three methods studied here, TEE is the "gold standard", matching autopsy results with near-perfect sensitivity and specificity (Schneider, et al. , 1996). However TEE is also the most difficult method to implement, requiring an internal esophagal probe, and is therefore not widely used. Currently, the easiest to use and most common PFO detection method is TTE, which uses an external chest probe. This method has a specificity of near 100%, but suffers from a low sensitivity rate (about 30%). More recently, TCD has been developed, which uses ultrasound probes to detect the presence of bubbles in cerebral arteries. Studies indicate that TCD is quite effective, having a sensitivity of about 91% and a specificity of about 93% (Droste, et al., 1999) when applied correctly, however implementation is difficult and requires considerable training.

Feiveson, Alan H.↗
NASA NTRS2011

Cardiac and Vascular Responses to Thigh Cuffs and Respiratory Maneuvers on Crewmembers of the International Space Station

The transition to microgravity eliminates the hydrostatic gradients in the vascular system. The resulting fluid redistribution commonly manifests as facial edema, engorgement of the external neck veins, and a decrease in leg diameter. This experiment examined the responses to modified Valsalva and Mueller maneuvers measured by cardiac and vascular ultrasound (ECHO) in a baseline steady state and during preload reduction introduced with thigh occlusion cuffs used as a counter-measure device (Braslet cuffs) measured by cardiac and vascular ultrasound examinations. Methods: Nine International Space Station crewmember subjects (Expeditions 16 - 20) were examined in 15 experiment sessions 101 +/- 46.days after launch (mean +/- SD; 33 - 185). Twenty Seven cardiac and vascular parameters were obtained with/without respiratory maneuvers before and after tightening of the Braslet cuffs. Results: Non-physicians performed diagnostic-quality cardiac and vascular ultrasound examinations using remote guidance. Three of 27 combinations of maneuvers and Braslet or Braslet alone were identified as being significant changed when compared to baseline. Eleven of 81 differences between combinations of Mueller, Valsalva or baseline were significant and related to cardiac preload reduction or increase in lower extremity venous volume. Conclusions: Acute application of Braslet occlusion cuffs causes lower extremity fluid sequestration and exerts commensurate measurable effects on cardiac performance in microgravity. Ultrasound techniques to measure the hemodynamic effects of thigh cuffs in combination with respiratory maneuvers may serve as an invaluable tool in determining the volume status of the cardiac patient at the 'microgravity bedside'.

Hamilton, Douglas↗
NASA NTRS2004

Geochemical and Mineralogical Indicators for Aqueous Processes in Gusev Crater and on Meridiani Planum

The Athena Science Instrument Payload is providing geochemical and mineralogical information for determining the properties of rocks, soils, and outcrops at the Mars Exploration Rovers landing sites. These measurements indicate that a variety of aqueous processes as well as various degrees of alteration occurred at the two landing sites. Light-toned rocks around the Spirit landing site appear to have coatings or alteration rinds that may have resulted from limited aqueous alteration on the surfaces of basaltic rocks. Hematite and high Fe(III)lFe(total) occur at the surfaces of these rocks. High concentrations of elements highly mobile in water (i.e., S, Cl, and Br) occur in rock veins, vugs, and coatings and at the bottom of soil trenches in the "intercrater plains." One scenario for the formation of rock coatings or rinds and translocation of mobile elements is that water might have occurred briefly at the Martian surface during periods of high obliquity and thin films of water may have mobilized elements and altered the surfaces of rocks. Outcrops on the slopes of the Columbia Hills appear to be extensively altered as suggested by their relative "softness" (measured as resistance to abrasion) as compared to basalts on the adjacent plains, high Fe(III)lFe(total), iron mineralogy dominated by nanophase Fe(III) oxides and hematite, and high Br and CI concentrations beneath outcrop surfaces. These outcrops may have formed by the alteration of basaltic rocks and/or volcaniclastic materials by solutions that were rich in volatile elements (e.g., Br, CI, S). However, it is not clear whether aqueous alteration occurred at depth (e.g., metasomatism), by hydrothermal solutions (e.g., associated with volcanic or impact processes), by vapors rich in volcanic gases, or by low-temperature solutions. The occurrence of jarosite, hematite, and other sulfates (e.g., Mg sulfates) in Eagle and Endurance crater outcrops are strong indicators of aqueous processes at Meridiani Planum. These phases occur with siliciclastic materials in outcrops. Jarosite can only form by aqueous processes under very acidic conditions; e.g., acid sulfate weathering conditions resulting from the oxidation of Fe sulfides or by sulfuric acid alteration of basalts by solutions associated with S02-rich volcanic gases. It is plausible that acidic solutions rich in sulfur (and Fe(II)) reacted with basaltic sediments (which provided a host of soluble cations) under oxidizing conditions and then, through evaporation, formed sediments rich in jarosite and other sulfates along with siliciclastic materials. Hematite-rich spherules in outcrops may have formed by aqueous processes within the sedimentary layers, which promoted transport of Fe (II) solutions to nucleation sites where oxidation and precipitation occurred to form hematite-rich spherules.

Ming, Douglas W.↗
NASA NTRS2005

Microwave Treatment of Prostate Cancer and Hyperplasia

Microwave ablation in the form of microwave energy applied to a heart muscle by a coaxial catheter inserted in a vein in the groin area can be used to heat and kill diseased heart cells. A microwave catheter has been developed to provide deep myocardial ablation to treat ventricular tachycardia by restoring appropriate electrical activity within the heart and eliminating irregular heartbeats. The resulting microwave catheter design, which is now being developed for commercial use in treating ventricular tachycardia, can be modified to treat prostate cancer and benign prostatic hyperplasia (BPH). Inasmuch as the occurrence of BPH is increasing currently 350,000 operations per year are performed in the United States alone to treat this condition this microwave catheter has significant commercial potential.

Arndt, G. Dickey↗
NASA NTRS2010

Oscillation of Angiogenesis with Vascular Dropout in Diabetic Retinopathy by VESsel GENeration Analysis (VESGEN)

PURPOSE. Vascular dropout and angiogenesis are hallmarks of the progression of diabetic retinopathy (DR). However, current evaluation of DR relies on grading of secondary vascular effects, such as microaneurysms and hemorrhages, by clinical examination instead of by evaluation of actual vascular changes. The purpose of this study was to map and quantify vascular changes during progression of DR by VESsel GENeration Analysis (VESGEN). METHODS. In this prospective cross-sectional study, 15 eyes with DR were evaluated with fluorescein angiography (FA) and color fundus photography, and were graded using modified Early Treatment Diabetic Retinopathy Study criteria. FA images were separated by semiautomatic image processing into arterial and venous trees. Vessel length density (L(sub v)), number density (N(sub v)), and diameter (D(sub v)) were analyzed in a masked fashion with VESGEN software. Each vascular tree was automatically segmented into branching generations (G(sub 1)...G(sub 8) or G(sub 9)) by vessel diameter and branching. Vascular remodeling status (VRS) for N(sub v) and L(sub v) was graded 1 to 4 for increasing severity of vascular change. RESULTS. By N(sub v) and L(sub v), VRS correlated significantly with the independent clinical diagnosis of mild to proliferative DR (13/15 eyes). N(sub v) and L(sub v) of smaller vessels (G(sub >=6) increased from VRS1 to VRS2 by 2.4 X and 1.6 X, decreased from VRS2 to VRS3 by 0.4 X and 0.6X, and increased from VRS3 to VRS4 by 1.7 X and 1.5 X (P < 0.01). Throughout DR progression, the density of larger vessels (G(sub 1-5)) remained essentially unchanged, and D(sub v1-5) increased slightly. CONCLUSIONS. Vessel density oscillated with the progression of DR. Alternating phases of angiogenesis/neovascularization and vascular dropout were dominated first by remodeling of arteries and subsequently by veins.

Parsons-Wingerter, Patricia↗
NASA NTRS2011

Validation of On-Orbit Methodology for the Assessment of Cardiac Function and Changes in the Circulating Volume Using "Braslet-M" Occlusion Cuffs

BACKGROUND: The transition to microgravity eliminates the hydrostatic gradients in the vascular system. The resulting fluid redistribution commonly manifests as facial edema, engorgement of the external neck veins, nasal congestion, and headache. This experiment examined the responses to modified Valsalva and Mueller maneuvers as measured by cardiac and vascular ultrasound in a baseline microgravity steady state, and under the influence of thigh occlusion cuffs (Braslet cuffs). METHODS: Nine International Space Station crewmember subjects (Expeditions 16 - 20) were examined in 15 experiment sessions 101 46 days after launch (mean SD; 33 - 185). 27 cardiac and vascular parameters were obtained under three respiratory conditions (baseline, Valsalva, and Mueller) before and after tightening of the Braslet cuffs for a total of 162 data points per session. The quality of cardiac and vascular ultrasound examinations was assured through remote monitoring and guidance by Investigators from the NASA Telescience Center in Houston, TX, USA. RESULTS: Fourteen of the 81 measured conditions were significantly different with Braslet application and were apparently related to cardiac preload reduction or increase in the venous volume sequestered in the lower extremity. These changes represented 10 of the 27 parameters measured. In secondary analysis, 7 of the 27 parameters were found to respond differently to respiratory maneuvers depending on the presence or absence of thigh compression, with a total of 11 differences. CONCLUSIONS: Acute application of Braslet occlusion cuffs causes lower extremity fluid sequestration and exerts proportionate measurable effects on cardiac performance in microgravity. Ultrasound techniques measuring the hemodynamic effects of thigh cuffs in combination with respiratory maneuvers may serve as an effective tool in determining the volume status of a cardiac or hemodynamically compromised patient in microgravity.

Hamilton, D. R.↗
NASA NTRS2012

Lower Limb Venous Compliance is Different Between Men and Women Following 60 Days of Head-Down Bedrest but Is Not Associated with Venoconstriction Dysfunction

Space flight-induced orthostatic intolerance (OI) is more prevalent in female (F) than male (M) astronauts. The mechanisms explaining the higher incidence of OI in F are unclear. We tested the hypothesis that venous compliance would be higher in F more than M following 6 deg head-down bed rest (BR) and would be associated with constrictor dysfunction. Using 2-D ultrasound, dorsal hand (DHV) and dorsal foot (DFV) vein compliances were determined in 24 subjects (10 F, 14 M; 35 +/- 1 yr) by measuring mean diameter response to increasing congestion pressure (0, 20, 30, and 40 mmHg) before and after 60 d of BR. Constrictor function was assessed by intravenous infusions of Ketorolac (KE; 1.5 ig/min) Phenylephrine (PE; 3160 ng/min), and L-NMMA (50 ig/min). The effects of BR between F vs. M and hand vs. foot were determined using mixed-effects linear regression. DFV but not DHV compliance changed in response to BR (p=0.012). Mean DFV increased significantly (0.903 mm to 1.191mm) in F but decreased in M (1.353 mm to 1.154 mm). DFV constrictor response was not different between sexes in response to BR (KE; p=0.647, PE; p=0.717, and L-NMMA; p=0.825). These BR data suggest that the higher incidence of OI in F astronauts may be related to increased lower limb venous compliance, contributing to blood pooling upon standing. Notably, changes to DFV compliance was not accompanied by impaired constrictor function.

Westby, Christian M.↗
NASA NTRS2013

Towed Subsurface Optical Communications Buoy

The innovation allows critical, high-bandwidth submarine communications at speed and depth. This reported innovation is a subsurface optical communications buoy, with active neutral buoyancy and streamlined flow surface veins for depth control. This novel subsurface positioning for the towed communications buoy enables substantial reduction in water-absorption and increased optical transmission by eliminating the intervening water absorption and dispersion, as well as by reducing or eliminating the beam spread and the pulse spreading that is associated with submarine-launched optical beams.

Stirbl, Robert C.↗
NASA NTRS1997

Mineralogy of Meteorite Groups

Approximately 275 mineral species have been identified in meteorites, reflecting diverse redox environments, and, in some cases, unusual nebular formation conditions. Anhydrous ordinary, carbonaceous and R chondrites contain major olivine, pyroxene and plagioclase; major opaque phases include metallic Fe-Ni, troilite and chromite. Primitive achondrites are mineralogically similar. The highly reduced enstatite chondrites and achondrites contain major enstatite, plagioclase, free silica and kamacite as well as nitrides, a silicide and Ca-, Mg-, Mn-, Na-, Cr-, K- and Ti-rich sulfides. Aqueously altered carbonaceous chondrites contain major amounts of hydrous phyllosilicates, complex organic compounds, magnetite, various sulfates and sulfides, and carbonates. In addition to kamacite and taenite, iron meteorites contain carbides, elemental C, nitrides, phosphates, phosphides, chromite and sulfides. Silicate inclusions in IAB/IIICD and lIE iron meteorites consist of mafic silicates, plagioclase and various sulfides, oxides and phosphates. Eucrites, howardites and diogenites have basaltic to orthopyroxenitic compositions and consist of major pyroxene and calcic plagioclase and several accessory oxides. Ureilttes .are made up mainly of calcic, chromian olivine and low-Ca clinopyroxene embedded in a carbonaceous matrix; accessory phases include the C polymorphs graphite, diamond, lonsdaleite and chaoite as well as metallic Fe-Ni, troilite and halides. Angrites are achondrites rich in fassaitic pyroxene (i.e. , AI-Ti diopside); minor olivine with included magnesian kirschsteinite is also present. Martian meteorites comprise basalts, Iherzolites, a dunite and an orthopyroxenite. Major phases include various pyroxenes and olivine; minor to accessory phases include various sulfides, magnetite, chromite and Ca-phosphates. Lunar meteorites comprise mare basalts with major augite and calcic plagioclase and anorthositic breccias with major calcic plagioclase. Several meteoritic phases were formed by shock metamorphism. Martensite (a2-fe,Ni) has a distorted body-centered-cubic structure and formed by a shear transformation from taenite during shock reheating and rapid cooling. The C polymorphs diamond, lonsdaleite and chaoite formed by shock from graphite. Suessite formed in the North Haig ureilite by reduction of Fe and Si (possibly from olivine) via reaction with carbonaceous matrix material. Ringwoodite, the spinel form of (Mg,Fe)2Si04, and majorite, a polymorph of (Mg,Fe)Si03 with the garnet structure, formed inside shock veins in highly shocked ordinary chondrites. Secondary minerals in meteorite finds that formed during terrestrial weathering include oxides and hy-. droxides formed directly from metallic Fe-Ni by oxidation, phosphates formed by the alteration of schreibersite, and sulfates formed by alteration of troilite.

Rubin, Alan E.↗