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At least 37 records · Page 2

Applications of dynamic crystallization studies - Lunar olivine-normative basalts

Dynamic crystallization studies were performed on two synthetic glasses similar in composition to the mare olivine-normative basalt samples 12009 and 15555. The effects of viscosity (primarily a function of FeO) and the initial temperature of cooling on mineral chemistry, texture, and temperature of appearance of phases were investigated. Olivine compositions seem to indicate that, for the two types of melt cooled at the same rate, there are no significant differences in the degree of undercooling at which olivine nucleates, but it is found that olivine-nucleated densities differ. The cooling rate of 15555 is estimated. Since the temperature at which cooling is initiated affects texture, mineral chemistry, and temperature of appearance of phases so greatly, caution is recommended in the application of experimental data to natural rock systems.

Bianco, A. S.↗

Nutritional Status Assessment (SMO 016E)

It has not been possible to assess nutritional status of crew members on the ISS during flight because blood and urine could not be collected during ISS missions. Postflight observations of alterations in nutritional status for several nutrients are troubling, and we require the ability to monitor the status of these nutrients during flight to determine if there is a specific impetus or timeframe for these changes. In addition to the monitoring of crew nutritional status during flight, in-flight sample collection would allow better assessment of countermeasure effectiveness. SMO 016E is also designed to expand the current medical requirement for nutritional assessment (MR016L) to include additional normative markers for assessing crew health and countermeasure effectiveness. Additional markers of bone metabolism will be measured to better monitor bone health and the effectiveness of countermeasures to prevent bone resorption. New markers of oxidative damage will be measured to better assess the type of oxidative insults that occur during space flight. The array of nutritional assessment parameters will be expanded to include parameters that will allow us to better understand changes in folate and vitamin B6 status, and related cardiovascular risk factors during and after flight. Additionally, stress hormones and hormones that affect bone and muscle metabolism will also be measured. This additional assessment will allow us to better monitor the health of crew members and make more accurate recommendations for their rehabilitation. Several nutritional assessment parameters are altered at landing, but it is not known how long these changes persist. We extended the current protocol to include an additional postflight blood and urine sample collection 30 days after landing. Data are being collected before, during, and after flight. These data will provide a complete survey of how nutritional status and related systems are affected by space flight. Analyzing the data will help us to define nutritional requirements for long-duration missions. This expanded set of measurements will also aid in the identification of nutritional countermeasures to counteract, for example, the deleterious effects of microgravity on bone and muscle and the effects of space radiation.

Smith, S. M.↗

Nutritional Status Assessment (SMO 016E)

Until 2006, it was not been possible to assess nutritional status of crewmembers on the ISS during flight because blood and urine could not be collected during ISS missions. Postflight observations of alterations in status of several nutrients are troubling, and we require the ability to monitor the status of these nutrients during flight to determine if there is a specific impetus or timeframe for these changes. In addition to the monitoring of crew nutritional status during flight, in-flight sample collection would allow better assessment of countermeasure effectiveness. Collecting samples during flight is one of the objectives of SMO 016E, and it is also designed to expand the current medical requirement for nutritional assessment (MR016L) to include additional normative markers for assessing crew health and countermeasure effectiveness. Additional markers of bone metabolism will be measured to better monitor bone health and the effectiveness of countermeasures to prevent bone resorption. New markers of oxidative damage will be measured to better assess the type of oxidative insults that occur during space flight. The array of nutritional assessment variables will be expanded to include ones that will allow us to better understand changes in folate, vitamin K, and vitamin B6 status, as well as risk factors for cardiovascular and oxidative damage during and after flight. Stress hormones and hormones that affect bone and muscle metabolism will also be measured. Measuring these additional variables will allow us to better monitor the health of crewmembers and make more accurate recommendations for their rehabilitation. Several nutritional assessment variables are altered at landing, but it is not known how long these changes persist. We extended the original protocol to include an additional postflight blood and urine sample collection 30 days after landing. Data are being collected before, during, and after flight. These data will provide a complete survey of how nutritional status and related systems are affected by space flight. Analyzing the data will help us to define nutritional requirements for long-duration missions. This expanded set of measurements will also aid in the identification of nutritional countermeasures to counteract, for example, the deleterious effects of microgravity on bone and muscle and the effects of space radiation.

Smith, S. M.↗

The Exploration Ethic: Its Historical-Intellectual Basis. Outlook for Space (1980 - 2000)

Principle components of the exploration ethic are discussed. Attempts were made to justify both the historical and intellectual aspects of the concept. It was noted that intellectual justification is strongly grounded on: (1) the complementarity of objective and normative inquiry as to method, and (2) interdisciplinary alliance of ethics of adaptive systems with contemporary decision sciences, as a theoretical basis. Historical exploration justification was associated with: (1) periods of civilization transition, (2) changes in the process of exploration which cause change in types of rationals used, sponsors involved, and explorers interest, and (3) the incorrectness of proven prior cost/benefit calculations.

Priscoli, J. D.↗

Quantitative micro-luminescence and related studies of fine and/or glassy lunar surface materials

Papers on Raman and soft X-ray spectroscopy of lunar glasses and electron microscopy of lunar fines are presented. Individual particles of glasses from Apollo 11, 12, 14, and 15 samples were analyzed separately. Silicon emission shifts vary between parent rock types and can be interpreted as a range of Si-O distances from 1.612 to 1.637 A. Aluminum emission shifts relate to the amount of 4- and 6-coordinated Al in the glass. Raman spectra show broadened bands. Certain bands recur in many specimens and relate to the main normative minerals for the glass bulk composition, olivine, pyroxene, and anorthite. Quantitative size and shape analyses were carried out on six Apollo 14 and 15 samples of fines by computer evaluation of scanning electron microspace images. For the size range of 0.50 to 30 micron diameter, the distributions are log-normal on a number count basis. Aspect ratios range from 0.1 to 1.0 with an average value of about 0.6. The aspect ratios and a shape complexity factor vary only slightly among the samples.

Roy, R.↗

Structure of lunar glasses by Raman and soft X-ray spectroscopy.

X-ray spectra and Raman spectra have been measured from individual particles of lunar glasses. Each particle was analyzed separately by electron microprobe. Silicon emission shifts vary between parent rock types and can be interpreted as a range of Si-O distances from 1.612 to 1.637 A. Aluminum emission shifts relate to the amount of 4- and 6-coordinated Al in the glass. Raman spectra show broadened bands. Certain bands recur in many specimens and relate to the main normative minerals for the glass bulk composition, olivine, pyroxene, and anorthite.

Fabel, G. W.↗

Enigmatic Nodule-Bearing Rocks in the Mafic to Ultramafic Diana Mills Pluton, Piedmont Province, Virginia

The Silurian Diana Mills pluton is a metamorphosed mafic-ultramafic body in the Piedmont Province of Virginia. Major rock types in the pluton include metadiorite and chlorite‐amphibole rock, with lesser amounts of hornblendite. However, the most visually striking rocks, found at 4 locations, consist of tan‐weathering nodules in a dark green matrix. The purpose of this study was to investigate the origin of these nodular rocks. All rocks show evidence of greenschistfacies metamorphism, but relict igneous textures are preserved locally. Apart from the nodules, Ca‐amphibole is ubiquitous in all rock types. Nodules are dominated by serpentine or talc (+magnetite +/- chromite), and many show a thin (less than or equal to 5 mm) radially oriented shell of serpentine against adjacent matrix. The nodules are ultramafic (Mg# approx. 80-90, up to7,563 ppm Cr, up to 2,038 ppm Ni), and their normative mineralogy is dominated by olivine and orthopyroxene. Thus, they represent metamorphosed harzburgites and pyroxenites. Matrix minerals are dominantly amphibole + chlorite, along with variable amounts of talc + magnetite. Some matrix samples are chlorite‐rich, probably reflecting metasomatic reaction with nodules (i.e., they are small‐scale ''blackwalls''). Matrix samples are also ultramafic (high Mg#, Cr, and Ni). The matrix of the nodule‐bearing outcrops is essentially the same as other chlorite‐amphibole rocks elsewhere in the pluton. We consider these rocks to represent emplacement of an original hornblende peridotite crystal mush (a mixture of crystals and hydrous melt), which locally carried harzburgitic nodules. The nodules most likely represent the earliest‐formed cumulates from the Diana Mills parent magma.

Owens, Brent E.↗

Noritic fragments in the Apollo 14 and 12 soils and the origin of Oceanus Procellarum.

Fragments of noritic breccias having a range of recrystallization textures and noritic basalts comprise about 80% of the 1 to 2 mm soil samples from Cone Crater (14142) and the bottom of the trench (14151). In five other samples, noritic fragments range in abundance from 42 to 56%. The remaining particles in each case are glasses, soil breccias, and glass-bonded aggregates; other crystalline rock types such as anorthosites constitute less than 1% of the soil. Noritic materials - i.e., Apollo 12 and 14 norites and ropy (KREEP) glass particles, can be divided into two broad groups on a chemical basis. The particles in one group have relatively high bulk TiO2 contents and high Fe/(Fe + Mg) ratios in their normative pyroxenes; the ropy glasses from Apollo 12 and 14 and a few Apollo 12 noritic rock fragments are in this category. Particles in the other class contain pyroxenes with a lower Fe/(Fe + Mg) and have a range of TiO2 contents; most noritic rock fragments from Apollo 12 and 14 are in this group. The ropy glasses may be from Copernicus or other rayed craters, but almost all the norites derive from the Fra Mauro formation or other noritic occurrences associated with Oceanus Procellarum.

Taylor, G. J.↗

Reconciling justice and attribution research to advance climate policy

The Paris Climate Agreement is an important step for international climate policy, but the compensation for negative effects of climate change based on clear assignment of responsibilities remains highly debated. From both a policy and a science perspective, it is unclear how responsibilities should be defined and on what evidence base. We explore different normative principles of justice relevant to climate change impacts, and ask how different forms of causal evidence of impacts drawn from detection and attribution research could inform policy approaches in accordance with justice considerations. Here, we reveal a procedural injustice based on the imbalance of observations and knowledge of impacts between developed and developing countries. This type of injustice needs to be considered in policy negotiations and decisions, and efforts strengthened to reduce it.

54 ENVIRONMENTAL SCIENCES↗

Petrology and geochemistry of olivine-normative and quartz-normative basalts from regolith breccia 15498 - New diversity in Apollo 15 mare basalts

Analysis of mare basalt clasts from Apollo 15 shows a greater diversity than previously recognized and provides new constraints on the petrogenesis of these basalts. The quartz-normative basalts (QNB) from 15498 are divided into four groups based on chemical variations: primitive, intermediate/1, intermediate/2, and evolved. The olivine-normative basalts (ONB) are divided into three groups: low-SiO2, high-SiO2, and olivine-pyroxene cumulates. Least-squares mixing calculations show that the high SiO2 ONBs may be parental to the QNB suite. Variations within the low-SiO2 ONBs are explained by olivine factionation. It is suggested that the presence of these basalt types may result from the position of breccia 15498 near the edge of the mare plain where normal ONBs are scarce, and from its presumed origin as ejecta from Dune Crater.

Vetter, Scott K.↗

Factorized visual representations in the primate visual system and deep neural networks

Object classification has been proposed as a principal objective of the primate ventral visual stream and has been used as an optimization target for deep neural network models (DNNs) of the visual system. However, visual brain areas represent many different types of information, and optimizing for classification of object identity alone does not constrain how other information may be encoded in visual representations. Information about different scene parameters may be discarded altogether (‘invariance’), represented in non-interfering subspaces of population activity (‘factorization’) or encoded in an entangled fashion. In this work, we provide evidence that factorization is a normative principle of biological visual representations. In the monkey ventral visual hierarchy, we found that factorization of object pose and background information from object identity increased in higher-level regions and strongly contributed to improving object identity decoding performance. We then conducted a large-scale analysis of factorization of individual scene parameters – lighting, background, camera viewpoint, and object pose – in a diverse library of DNN models of the visual system. Models which best matched neural, fMRI, and behavioral data from both monkeys and humans across 12 datasets tended to be those which factorized scene parameters most strongly. Notably, invariance to these parameters was not as consistently associated with matches to neural and behavioral data, suggesting that maintaining non-class information in factorized activity subspaces is often preferred to dropping it altogether. Thus, we propose that factorization of visual scene information is a widely used strategy in brains and DNN models thereof.

59 BASIC BIOLOGICAL SCIENCES↗

Major element chemical compositions of chondrules in unequilibrated chondrites

The chemical compositions (except for metals and sulfides in chondrules) of more than 500 chondrules from unequilibrated E, H, L, LL, and C chondrites were measured using a broad beam of an electron-probe microanalyzer. The compositions of chondrules can be represented by various mixtures of normative compositions of olivine, low-Ca pyroxene, plagioclase, and high-Ca pyroxene with minor amounts of spinel, feldspathoid, SiO2-minerals, etc., indicating that the chondrule precursor materials consisted of aggregates of these minerals. The Al, Na, and K contents of most chondrules reflect the compositions of the ternary feldspar (An-Ab-Kf) of the chondrule precursor materials, and chemical types of chondrules (KF, SP, IP, and CP) are defined on the basis of the atomic proportion of Al, Na, and K.

Ikeda, Y.↗

Geology and petrology of the Apollo 15 landing site - Past, present, and future understanding

The main objectives of the Apollo 15 lunar mission were to investigate and sample materials from the Apennine Front (expected to be Imbrium ejecta and pre-Imbrian materials), the Hadley Rille, and the mare lavas of Palus Putredinis. The Hadley Rille was found to be a collapsed lava tube or channel, and from it, many mare basalt samples were collected which form two main chemical groups of the same age (3.3 b.y.), isotopic characteristics, and rate-earth element patterns. One group, olivine-normative, contains many vescular specimens and shows an olivine fraction trend. The other group, quartz-normative, is pigeonite-phyric and contains both vitrophyric and coarse-grained samples but exhibits little fractionation. The Apennine Front samples include such highland materials as ferroan anorthosites, spinel-bearing troctolites, norites, impact melts and metamorphosed breccias. A conspicuous component of the regolith breccias is volcanic green glass. The Apennine Front is characterized by a low-KREEP composition, a composition which has never been found as a pristine igneous rock type. Another unexpected discovey was the common occurrence of 3.5 b.y. old volcanic KREEP basalts. It is concluded that all major lunar processes can be profitably studied from the samples and observations at this single location.

Spudis, P. D.↗

Apollo 17 KREEPy basalt - A rock type intermediate between mare and KREEP basalts

The Apollo 17 KREEPy basalt is a unique lunar volcanic rock, observed only as clasts in the light friable breccia matrix (72275) of Boulder 1, Station 2 at Taurus-Littrow. Its status as a volcanic rock is confirmed by the absence of any meteoritic contamination, a lack of cognate inclusions or xenocrystal material, and low Ni contents in metal grains. The basalt was extruded 4.01 + or - 0.04 b.y. ago, approximately contemporaneously with the high-alumina mare basalts at Fra Mauro; shortly afterwards it was disrupted, probably by the Serenitatis impact, and its fragments emplaced in the South Massif. The basalt, which is quartz-normative and aluminous, is chemically and mineralogically intermediate between the Apollo 15 KREEP basalts and the high-alumina mare basalts in most respects. It consists mainly of plagioclase and pigeonitic pyroxene in approximately equal amounts, and 10-30% of mesostatis.

Ryder, G.↗

Trends and individual differences in response to short-haul fight operations

A survey of airline pilots was undertaken to determine normative patterns and individual differences in mood and sleep during short-haul flight operations. The results revealed that over the course of a typical 2-d trip, pilots experience a decline in positive mood, or activity, and an increase in negative mood, or tension. On layovers, pilots report experiencing sleep of shorter duration and poorer quality than at home. These patterns are very similar to those reported by Gander and Graeber and by Gander et al. using high-fidelity sleep and activity monitoring equipment. Examination of the impact of two personality dimensions extracted from the Jenkins Activity Survey measure of the Type A personality, Achievement Striving and Impatience/Irritability, suggested that Impatience/Irritability may serve as a marker of individuals most likely to experience health-related problems on trips. Achievement Striving may serve as a predictor of performance in crew settings.

Aircraft↗

Simulator Evaluation of a New Cockpit Descent Procedure

An experiment was conducted to evaluate flight crew performance of the "Precision Descent," a new cockpit procedure designed to support the Descent Advisor (DA), one of the components in a new air traffic control advisory system called the "Center-TRACON Automation System" (CTAS). The DA predicts when aircraft will reach a specific waypoint on the arrival route, and presents controllers with clearance advisories designed to improve the sequencing of arriving aircraft. The effectiveness of the DA depends on the aircraft's descent trajectory: where it begins descent, what speed it maintains, how fast and at what altitude it crosses the bottom-of-descent waypoint. The Precision Descent allows controllers to assign these descent parameters to the flight crew. A Field Evaluation of the DA was conducted in Denver in 1995. Three separate clearances using standard ATC phraseology were used to support the cockpit descent procedure during this evaluation. The number and length of these clearances caused problems for both controllers and flight crews, causing readback errors, repeat requests and procedure misunderstandings. These observations led to a focus group meeting in which controller and pilot participants in the 1995 FE assisted in the redesign of the procedure. The Precision Descent eliminates one clearance used in the earlier study, and greatly reduces the length of the remaining clearances. This was accomplished by using non-standard clearance phraseology that relies on a published procedure chart for correct interpretation. Eight type-rated flight crews flew eight Precision Descents in a Boeing 747-400 simulator. No training was provided: crews received either a procedure chart or a procedure chart with a flight manual bulletin describing procedure techniques. Video and digital data were recorded for each descent. Preliminary results indicate that moving information from the verbal clearance to the chart was successful: the shorter clearances and the procedure's default crossing restriction were understood, and procedure compliance of 81% was observed across all descents on six independent compliance measures. Some readback errors and procedure misunderstandings were still observed, however; particularly when descent clearances deviated from the normative procedure.

Crane, Barry↗

Trends and individual differences in response to short-haul flight operations

A survey of airline pilots was undertaken to determine normative patterns and individual differences in mood and sleep during short-haul flight operations. The results revealed that over the course of a typical 2-d trip, pilots experience a decline in positive mood, or activity, and an increase in negative mood, or tension. On layovers, pilots report experiencing sleep of shorter duration and poorer quality than at home. These patterns are very similar to those reported by Gander and Graeber (1987) and by Gander et al. (1988), using high-fidelity sleep and activity monitoring equipment. Examination of the impact of two personality dimensions extracted from the Jenkins Activity Survey measure of the Type A personality, Achievement Striving and Impatience/Irritability, suggested that Impatience/Irritability may serve as a marker of individuals most likely to experience health-related problems on trips. Achievement Striving may serve as a predictor of performance in crew settings.

Chidester, Thomas R.↗

Compositional Variation in Apollo 16 Impact-Melt Breccias and Inferences for the Geology and Bombardment History of the Central Highlands of the Moon

High-precision data for the concentrations of a number of lithophile and siderophile elements were obtained on multiple subsamples from 109 impact-melt rocks and breccias (mostly crystalline) from the Apollo 16 site. Compositions of nearly all Apollo 16 melt rocks fall on one of two trends of increasing Sm concentration with increasing Sc concentration. The Eastern trend (lower Sm/Sc, Mg/Fe, and Sm/Yb ratios) consists of compositional groups 3 and 4 of previous classification schemes. These melt rocks are feldspathic, poor in incompatible and siderophile elements, and appear to have provenance in the Descartes formation to the east of the site. The Western trend (higher Sm/Sc. Mg/Fe, and Sm/ Yb ratios) consists of compositional groups 1 and 2. These relatively mafic, KREEP-bearing breccias are a major component (approx.35%) of the Cayley plains west of the site and are unusual, compared to otherwise similar melt breccias from other sites, in having high concentrations of Fe-Ni metal ( 1-2 %). The metal is the carrier of the low-Ir/Au (approx. 0.3 x chondritic) siderophile-element signature that is characteristic of the Apollo 16 site. Four compositionally distinct groups (1M, 1F, 2DB, and 2NR) of Western-trend melt breccias occur that are each represented by at least six samples. Compositional group 1 or previous classification schemes (the 'poikilitic' or 'LKFM' melt breccias) can be subdivided into two groups. Group 1M (represented by six samples, including 60315) is characterized by lower Al2O3 concentrations, higher MgO and alkali concentrations, and higher Mg/Fe and Cr/Sc ratios than group 1F (represented by fifteen samples, including 65015). Group 1M also has siderophile-element concentrations averaging about twice those of group lF and Ir/Au and Ir/Ni ratios that are even lower than those of other Western-trend melt rocks (Ir/Au = 0.24 +/- 0.03. CI-normalized). At the mafic extreme of group 2 ('VHA' melt breccias), the melt lithology occurring as clasts in feldspathic fragmental breccias from North Ray crater (group 2NR) is compositionally distinct from the melt lithology ofdimict breccias from the Cayley plains (group 2DB) in having higher concentrations of Sc, Cr, and heavy rare earth elements and lower concentrations of siderophile elements. The distinct siderophile-element signature (high absolute abundances, low Ir/Au ratio) suggest that the four groups ofmafic melt breccia are all somehow related. Ratios ofsome lithophile elements also suggest that they are more closely related to each other than then, are to melt breccias from other Apoll sites. However, none of the breccia compositions can be related to any of the others by any simple process of igneous fractionation or mixing involving common lunar materials. Thus, the origin of the four groups of mafic melt breccia is enigmatic. If they were produced in only one or two impacts, then a mechanism exists for generating regimes of impact-melt breccia in a single impact that are substantially different from each other in composition. For various reasons, including the problem of delivering large volumes of four different types of melt to the Apollo 16 site, it is unlikely that any of these breccias were produced in basin-forming impacts. If they were produced in as many as four crater-forming impacts, then the unusual siderophile-element signature is difficult to explain. Possible explanations are (1) the four groups of melt breccia all contain metal from a single, earlier impact, (2) they were each formed by related metal-rich meteoroids, or (3) some common postimpact process has resulted in metal of similar composition in each of four melt pools. Within a compositional group, most intrasample and intersample variation in lithophile element concentrations is caused by differences among samples in the proportion of a component of normative anorthosite or noritic anorthosite. In most cases, this compositional variation probably reflects variation in clast abundance. For group 2DB (and probably 2NR), differences in abundance of a component of ferroan anorthosite (estimated Al2O3 approx. 32%) accounts for the compositional variation. For groups 1M and 1F, the anorthositic component is more mafic (estimated Al203 approx. 26%). Some group-2 samples may be related by a troctolitic component of varying abundance.

Korotev, Randy L.↗