547 research outputs found

    ISO 15859 Propellant and Fluid Specifications: A Review and Comparison with Military and NASA Specifications

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    This work presents an overview of the International Organization for Standardization (ISO) 15859 International Standard for Space Systems Fluid Characteristics, Sampling and Test Methods Parts 1 through 13 issued in June 2004. These standards establish requirements for fluid characteristics, sampling, and test methods for 13 fluids of concern to the propellant community and propellant characterization laboratories: oxygen, hydrogen, nitrogen, helium, nitrogen tetroxide, monomethylhydrazine, hydrazine, kerosene, argon, water, ammonia, carbon dioxide, and breathing air. A comparison of the fluid characteristics, sampling, and test methods required by the ISO standards to the current military and NASA specifications, which are in use at NASA facilities and elsewhere, is presented. Many ISO standards composition limits and other content agree with those found in the applicable parts of NASA SE-S-0073, NASA SSP 30573, military performance standards and details, and Compressed Gas Association (CGA) commodity specifications. The status of a current project managed at NASA Johnson Space Center White Sands Test Facility (WSTF) to rewrite these documents is discussed

    Nonrandom Territory Occupancy by Nesting Gyrfalcons (\u3ci\u3eFalco rusticolus\u3c/i\u3e)

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    We know little regarding how specific aspects of habitat influence spatial variation in site occupancy by Arctic wildlife, yet this information is fundamental to effective conservation. To address this information gap, we assessed occupancy of 84 Gyrfalcon (Falco rusticolus Linnaeus, 1758) breeding territories observed annually between 2004 and 2013 in western Alaska. In line with the theory of population regulation by site dependence, we asked whether Gyrfalcons exhibited a nonrandom pattern of site selection and if heterogeneous landscape attributes correlated with observed occupancy patterns. We characterized high- and low-occupancy breeding territories as those occupied more or less often than expected by chance, and we evaluated land cover at 1 and 15 km circles centered around nesting territories to identify habitat variables associated with observed occupancy patterns. We tested 15 competing models to rank hypotheses reflecting prey and habitat variables important to nesting Gyrfalcons. We confirmed a nonrandom pattern of site selection but found only weak evidence that the distribution of prey habitat was responsible for this pattern. We reason that preferential habitat use by nesting Gyrfalcons may be determined by spatial scales other than those we measured or may be driven by landscape-level attributes at time periods other than during the brood rearing period

    A Synthetic 21-cm Galactic Plane Survey of an SPH Galaxy Simulation

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    We have created synthetic neutral hydrogen (HI) Galactic Plane Survey data cubes covering 90 degrees < l < 180 degrees, using a model spiral galaxy from SPH simulations and the radiative transfer code TORUS. The density, temperature and other physical parameters are fed from the SPH simulation into TORUS, where the HI emissivity and opacity are calculated before the 21-cm line emission profile is determined. Our main focus is the observation of Outer Galaxy `Perseus Arm' HI, with a view to tracing atomic gas as it encounters shock motions as it enters a spiral arm interface, an early step in the formation of molecular clouds. The observation of HI self-absorption features at these shock sites (in both real observations and our synthetic data) allows us to investigate further the connection between cold atomic gas and the onset of molecular cloud formation.Comment: MNRAS accepted; 11 pages, 12 figure

    Can Increased Training and Awareness Take Forest Research to New Heights?

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    Forest canopies contribute significantly to global forest biodiversity and ecosystem functioning, yet are declining and understudied. One reason for a knowledge gap is that accessing forest canopies can be difficult and dangerous. Thus, lack of relevant canopy access skills may compromise knowledge gain and personal safety. We assessed skill levels in canopy access methods and self-perception of skills amongst ecologists worldwide via a web-based survey, available in four languages. We obtained responses from expert arborists as a control group. From 191 respondents who said canopy access is relevant to their research (of 1,070 total responses), we found that ecologists are not attaining the full potential provided by existing methods of canopy access. Specifically, most respondents are unable to access much of the forest canopy, especially areas away from the trunk and between trees. The survey further revealed the common use of unsafe and inefficient practices among ecologists and that few are adequately equipped with aerial rescue skills. Importantly, ecologists with the lowest skill levels overestimate their expertise the most. Proper field techniques are key components of good science: they can improve study design, increase potential for data collection, and ultimately reveal greater knowledge on canopy organisms and processes. By safely allowing greater access to the forest canopy, proper techniques can reduce bias in our scientific understanding of forest ecology. To facilitate safe and effective canopy access for ecological research, we recommend increasing instruction and collaboration, implementing certification programs, and conducting audits of canopy research programs. With increased access to such opportunities, ecologists will acquire improved skills in accessing forest canopies, develop a greater appreciation for the full breadth of possibilities among methods of canopy access, and more safely and effectively gather the data needed to better understand forest ecosystems

    Including ultrasound scans in antenatal care in low-resource settings: Considering the complementarity of obstetric ultrasound screening and maternity waiting homes in strengthening referral systems in low-resource, rural settings

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    Recent World Health Organization (WHO) antenatal care recommendations include an ultrasound scan as a part of routine antenatal care. The First Look Study, referenced in the WHO recommendation, subsequently shows that the routine use of ultrasound during antenatal care in rural, low-income settings did not improve maternal, fetal or neonatal mortality, nor did it increase women\u27s use of antenatal care or the rate of hospital births. This article reviews the First Look Study, reconsidering the assumptions upon which it was built in light of these results, a supplemental descriptive study of interviews with patients and sonographers that participated in the First Look study intervention, and a review of the literature. Two themes surface from this review. The first is that focused emphasis on building the pregnancy risk screening skills of rural primary health care personnel may not lead to adaptations in referral hospital processes that could benefit the patient accordingly. The second is that agency to improve the quality of patient reception at referral hospitals may need to be manufactured for obstetric ultrasound screening, or remote pregnancy risk screening more generally, to have the desired impact. Stemming from the literature, this article goes on to examine the potential for complementarity between obstetric ultrasound screening and another approach encouraged by the WHO, the maternity waiting home. Each approach may address existing shortcomings in how the other is currently understood. This paper concludes by proposing a path toward developing and testing such a hybrid approach

    EVA-SCRAM operations

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    This paper wrestles with the on-orbit operational challenges introduced by the proposed Space Construction, Repair, and Maintenance (SCRAM) tool kit for Extra-Vehicular Activity (EVA). SCRAM undertakes a new challenging series of on-orbit tasks in support of the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These new EVA tasks involve welding, brazing, cutting, coating, heat-treating, and cleaning operations. Anticipated near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by atomic oxygen, and cleaning of optical, solar panel, and high emissivity radiator surfaces which have been degraded by contaminants. Future EVA-SCRAM applications are also examined, involving mass production tasks automated with robotics and artificial intelligence, for construction of large truss, aerobrake, and reactor shadow shield structures. Realistically achieving EVA-SCRAM is examined by addressing manual, teleoperated, semi-automated, and fully-automated operation modes. The operational challenges posed by EVA-SCRAM tasks are reviewed with respect to capabilities of existing and upcoming EVA systems, such as the Extravehicular Mobility Unit, the Shuttle Remote Manipulating System, the Dexterous End Effector, and the Servicing Aid Tool

    The Indo-U.S. Library of Coude Feed Stellar Spectra

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    We have obtained spectra for 1273 stars using the 0.9m Coud\'e Feed telescope at Kitt Peak National Observatory. This telescope feeds the coud\'e spectrograph of the 2.1m telescope. The spectra have been obtained with the #5 camera of the coud\'e spectrograph and a Loral 3K X 1K CCD. Two gratings have been used to provide spectral coverage from 3460 \AA to 9464 \AA, at a resolution of \sim1\AA FWHM and at an original dispersion of 0.44 \AA/pixel. For 885 stars we have complete spectra over the entire 3460 \AA to 9464 \AA wavelength region (neglecting small gaps of << 50 \AA), and partial spectral coverage for the remaining stars. The 1273 stars have been selected to provide broad coverage of the atmospheric parameters Teff_{eff}, log g, and [Fe/H], as well as spectral type. The goal of the project is to provide a comprehensive library of stellar spectra for use in the automated classification of stellar and galaxy spectra and in galaxy population synthesis. In this paper we discuss the characteristics of the spectral library, viz., details of the observations, data reduction procedures, and selection of stars. We also present a few illustrations of the quality and information available in the spectra. The first version of the complete spectral library is now publicly available from the National Optical Astronomy Observatory (NOAO) via FTP and HTTP.Comment: 18 pages, 6 figures, 4 table

    The SCRAM tool-kit

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    This paper proposes a new series of on-orbit capabilities to support the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These proposed capabilities form a toolkit termed Space Construction, Repair, and Maintenance (SCRAM). SCRAM addresses both intra-Vehicular Activity (IVA) and Extra-Vehicular Activity (EVA) needs. SCRAM provides a variety of tools which enable welding, brazing, cutting, coating, heating, and cleaning, as well as corresponding nondestructive examination. Near-term IVA-SCRAM applications include repair and modification to fluid lines, structure, and laboratory equipment inside a shirt-sleeve environment (i.e. inside Spacelab or Space Station). Near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by contaminants. The SCRAM tool-kit also promises future EVA applications involving mass production tasks automated by robotics and artificial intelligence, for construction of large truss, aerobrake, and nuclear reactor shadow shields structures. The leading candidate tool processes for SCRAM, currently undergoing research and development, include Electron Beam, Gas Tungsten Arc, Plasma Arc, and Laser Beam. A series of strategic space flight experiments would make SCRAM available to help conquer the space frontier

    Development of NASA's Small Fission Power System for Science and Human Exploration

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    Exploration of our solar system has brought many exciting challenges to our nations scientific and engineering community over the past several decades. As we expand our visions to explore new, more challenging destinations, we must also expand our technology base to support these new missions. NASAs Space Technology Mission Directorate is tasked with developing these technologies for future mission infusion and continues to seek answers to many existing technology gaps. One such technology gap is related to compact power systems (1 kWe) that provide abundant power for several years where solar energy is unavailable or inadequate. Below 1 kWe, Radioisotope Power Systems have been the workhorse for NASA and will continue to be used for lower power applications similar to the successful missions of Voyager, Ulysses, New Horizons, Cassini, and Curiosity. Above 1 kWe, fission power systems become an attractive technology offering a scalable modular design of the reactor, shield, power conversion, and heat transport subsystems. Near term emphasis has been placed in the 1-10kWe range that lies outside realistic radioisotope power levels and fills a promising technology gap capable of enabling both science and human exploration missions. History has shown that development of space reactors is technically, politically, and financially challenging and requires a new approach to their design and development. A small team of NASA and DOE experts are providing a solution to these enabling FPS technologies starting with the lowest power and most cost effective reactor series named Kilopower that is scalable from approximately 1-10 kWe

    A Report of Florida’s Cancer History, Risk Factors, and Screening Behaviors: Data from the National Health Interview Survey

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    To target populations at greatest risk ofdeveloping cancer, it is vital to understand the patterns ofrisk factors and screening behaviors along with cancer surveillance data. This study provides data on the prevalence of self-reported cancer history, can- cer risk factors, and cancer screening behaviors in Florida and compares them to rates in the rest ofthe U.S. Data were ob- tained from the National Health Interview Survey (NHIS), an annual, cross-sectional household survey of the U.S. civilian non-institutionalized population. We analyzed pooled data from the 2000 and 2005 Cancer Control Modules. Compared to the rest ofthe U.S., Floridians reported a lower prevalence ofcurrent smoking, risky drinking, and obesity, and a greater pre- valence ofProstate Specific Antigen (PSA) testing. However, Floridians reported a greater prevalence ofcancer history and a lower prevalence of physical activity, concern for sun protection, lifetime colorectal cancer screening, lifetime breast exam, life- time mammography screening, and lifetime and past year Pap test. The data indicate that Florida lags behind the rest of the U.S. in several areas, particularly cancer screening, and falls short ofthe Healthy People 2020 objectives for health behaviors and screening. These results provide information for key stakeholders and public health policy makers to effectively target Flor- ida residents at greatest risk for cancer and those not receiving recommended cancer screenings. This study also represents a model ofvaluable state-level evaluations that can be conducted using NHIS data. These types ofanalyses can provide a great- er understanding of state-level variations and lead to more effective public health interventions aimed at reducing cancer bur- den
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