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Many tons of dust grains, including samples of asteroids and comets, fall from space into the Earth's atmosphere each day. NASA periodically collects some of these particles from the Earth's stratosphere using sticky collectors mo...
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Many tons of dust grains, including samples of asteroids and comets, fall from space into the Earth's atmosphere each day. NASA periodically collects some of these particles from the Earth's stratosphere using sticky collectors mounted on NASA's high-flying aircraft. Sometimes, especially when the Earth experiences a known meteor shower, a special opportunity is presented to associate cosmic dust particles with a known source. NASA JSC's Cosmic Dust Collection Program has made special attempts to collect dust from particular meteor showers and asteroid families when flights can be planned well in advance. However, it has rarely been possible to make collections on very short notice. In 2012, the Draconid meteor shower presented that opportunity. The Draconid meteor shower, originating from Comet 21P/Giacobini-Zinner, has produced both outbursts and storms several times during the last century, but the 2012 event was not predicted to be much of a show. Because of these predictions, the Cosmic Dust team had not targeted a stratospheric collection effort for the Draconids, despite the fact that they have one of the slowest atmospheric entry velocities (23 km/s) of any comet shower, and thus offer significant possibilities of successful dust capture. However, radar measurements obtained by the Canadian Meteor Orbit Radar during the 2012 Draconids shower indicated a meteor storm did occur October 8 with a peak at 16:38 (+/-5 min) UTC for a total duration of approximately 2 hours.
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Whether groups make better judgments and decisions than individuals has been studied extensively, but most of this research has focused on static tasks. How do groups and individuals compare in settings where the decision environm...
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Whether groups make better judgments and decisions than individuals has been studied extensively, but most of this research has focused on static tasks. How do groups and individuals compare in settings where the decision environment changes unexpectedly and without notification. This article examines group and individual behavior in decisions from experience where the underlying probabilities change after some trials. Consistent with the previous literature, the results showed that groups performed better than the average individual while the decision task was stable. However, group performance was no longer superior after a change in the decision environment. Group performance was closer to the benchmark of Bayesian updating, which assumed perfect memory. Findings suggest that groups did not adopt decision routines that might have delayed their adaption to change in the environment. Rather, they seem to have coordinated their responses, which led them to behave as if they had better memory and subsequently delayed adaptation.
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Papers presented at the first Lunar Science Conference (1) and those published in the subsequent Science Moon Issue (2) reported the C content of Apollo II soils, breccias, and igneous rocks as rang-ing from approx.50 to 250 parts...
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Papers presented at the first Lunar Science Conference (1) and those published in the subsequent Science Moon Issue (2) reported the C content of Apollo II soils, breccias, and igneous rocks as rang-ing from approx.50 to 250 parts per million (ppm). Later Fegley & Swindle (3) summarized the C content of bulk soils from all the Apollo missions as ranging from 2.5 (Apollo 15) to 280 ppm (Apollo 16) with an overall average of 124+/- 45 ppm. These values are unexpectedly low given that multiple processes should have contributed (and in some cases continue to contribute) to the lunar C inventory. These include exogenous accretion of cometary and asteroidal dust, solar wind implantation, and synthesis of C-bearing species during early lunar volcanism. We estimate the contribution of C from exogenous sources alone is approx. 500 ppm, which is approx. 4x greater than the reported average.
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The assessment of indigenous organic matter in returned lunar samples was one of the primary scientific goals of the Apollo program. The levels of such organic material were expected to be and found to be small. Previous work on t...
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The assessment of indigenous organic matter in returned lunar samples was one of the primary scientific goals of the Apollo program. The levels of such organic material were expected to be and found to be small. Previous work on this topic includes Murphy et al. (1) who reported the presence of anthropogenic organics with sub-ppm concentrations in Apollo 11 fines. In Apollo 12 samples, Preti et al. (2) detected low levels, < 10 ppb or below, of more complex organic material that may have been synthesized by abrupt heating during analysis. Kvenvolden et al. (3) detected porphyrin-like pigments at the ng to pg level in an Apollo 11 bulk sample. Hodgson et al. (4) and Ponnamperuma et al. (5) suggested that most if not all porphyrins were synthesized from rocket fuel during module landing. Chang et al. (6) reported indigenous carbon ranging from 5-20 g/g in the form of metal carbides in Apollo 11 fines. Hare et al. (7) reported amino acids at he 50 ng/g level in Apollo 11 samples but suggested the results may be explained as contamination. More recently, Clemett et al. (8) reported simple polycyclic aromatic hydrocarbons at concentrations of < 1ppm in an Apollo 16 soil. Low concentrations of lunar organics may be a consequence not only of its paucity, but also its heterogeneous distribution. If the sample size required for a measurement is large relative to the localization of organics, detection is limited not by ultimate sensitivity but rather by the ability to distinguish an indigenous signature from background contamination (9).
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What type of analysis should be used to inform design when both the future organizational structure and the experimental simulation are tenuous? Neither the application of a qualitative process tracing method nor low-level quantit...
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What type of analysis should be used to inform design when both the future organizational structure and the experimental simulation are tenuous? Neither the application of a qualitative process tracing method nor low-level quantitative organizational designs are warranted. We hypothesized the analyses of high-level communication patterns in a role-playing exercise of a future organization structure would yield results that could both inform organizational design and shape iterative experimental designs. This study summarizes the comparison between communication patterns in an envisioned organizational structure and the actual patterns of information exchange of experienced military participants role-playing staff members in a future organizational design. The comparison between the hypothesized and actual communication performance indicated a different distribution of communication interaction from the expected. These results help guide both the future organizational concept as well as next iteration experiments.
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The regional convective heat transfer coefficients(hc) on the human body were determined using sublimating naphthalene disks. Circular naphthalene disks were affixed to various body segments of a stationary, life-size mannequin, u...
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The regional convective heat transfer coefficients(hc) on the human body were determined using sublimating naphthalene disks. Circular naphthalene disks were affixed to various body segments of a stationary, life-size mannequin, under constant temperature and wind speed in an environmental chamber. The amount of naphthalene weight loss through sublimation was translated to hc using the Chilton-Colburn j-factor analogy between heat and mass transfer. The regional convective heat transfer coefficients can be determined by using strictly the heat-mass transfer analogy, excluding any supplementary technique of cylindrical body segment approximations or other shape extrapolations. The logarithmic mean density factor for naphthalene sublimating in air (PAM,n) was also determined. PAM,n for the naphthalene-air sublimation environment is only one third of the water vapor-air diffusion environment (Pam). Pam,n is an essential factor for extracting the correct hc value from the naphthalene mass transfer data. Keywords; Heat transfer coefficients; Convective heat transfer; Heat-mass transfer analogy; Naphthalene disk sublimation; Body temperature. (kt)
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