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NASA Technical Reports Server (NTRS) (685.044 recursos)

The NTRS is a valuable resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994. NTRS provides access to approximately 500K aerospace related citations, 90K full-text online documents, and 111K images and videos. NTRS numbers continues to grow over time as new scientific and technical information (STI) is created or funded by NASA. The type of information found in NTRS include: conference papers, images, journal articles, photos, meeting papers, movies, patents, research reports, and technical videos.

NASA Center for AeroSpace Information (CASI)

Mostrando recursos 1 - 20 de 424.139

  1. Cell Cycle Progression of Human Cells Cultured in Rotating Bioreactor

    Parks, Kelsey
    Space flight has been shown to alter the astronauts immune systems. Because immune performance is complex and reflects the influence of multiple organ systems within the host, scientists sought to understand the potential impact of microgravity alone on the cellular mechanisms critical to immunity. Lymphocytes and their differentiated immature form, lymphoblasts, play an important and integral role in the body's defense system. T cells, one of the three major types of lymphocytes, play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and natural killer cells by the presence of a...

  2. Digital Astronaut Photography: A Discovery Dataset for Archaeology

    Stefanov, William L.
    Astronaut photography acquired from the International Space Station (ISS) using commercial off-the-shelf cameras offers a freely-accessible source for high to very high resolution (4-20 m/pixel) visible-wavelength digital data of Earth. Since ISS Expedition 1 in 2000, over 373,000 images of the Earth-Moon system (including land surface, ocean, atmospheric, and lunar images) have been added to the Gateway to Astronaut Photography of Earth online database (http://eol.jsc.nasa.gov ). Handheld astronaut photographs vary in look angle, time of acquisition, solar illumination, and spatial resolution. These attributes of digital astronaut photography result from a unique combination of ISS orbital dynamics, mission operations, camera systems,...

  3. An Analytical Model for the Prediction of a Micro-Dosimeter Response Function

    Xapsos, Mike; Badavi, Francis F.
    A rapid analytical procedure for the prediction of a micro-dosimeter response function in low Earth orbit (LEO), correlated with the Space Transportation System (STS, shuttle) Tissue Equivalent Proportional Counter (TEPC) measurements is presented. The analytical model takes into consideration the energy loss straggling and chord length distribution of the detector, and is capable of predicting energy deposition fluctuations in a cylindrical micro-volume of arbitrary aspect ratio (height/diameter) by incoming ions through both direct and indirect (ray) events. At any designated (ray traced) target point within the vehicle, the model accepts the differential flux spectrum of Galactic Cosmic Rays (GCR) and/or...

  4. Arctic Mixed-phase Clouds Simulated by a Cloud-Resolving Model: Comparison with ARM Observations and Sensitivity to Microphysics Parameterizations

    Mcfarquhar, G.M.; Xu, Kuan-Man; Luo, Yali; Morrison, Hugh
    Single-layer mixed-phase stratiform (MPS) Arctic clouds, which formed under conditions of large surface heat flux combined with general subsidence during a subperiod of the Atmospheric Radiation Measurement (ARM) Program Mixed-Phase Arctic Cloud Experiment (M-PACE), are simulated with a cloud resolving model (CRM). The CRM is implemented with either an advanced two-moment (M05) or a commonly used one-moment (L83) bulk microphysics scheme and a state-of-the-art radiative transfer scheme. The CONTROL simulation, that uses the M05 scheme and observed aerosol size distribution and ice nulei (IN) number concentration, reproduces the magnitudes and vertical structures of cloud liquid water content (LWC), total ice...

  5. Consistency, Verification, and Validation of Turbulence Models for Reynolds-Averaged Navier-Stokes Applications

    Rumsey, Christopher L.
    In current practice, it is often difficult to draw firm conclusions about turbulence model accuracy when performing multi-code CFD studies ostensibly using the same model because of inconsistencies in model formulation or implementation in different codes. This paper describes an effort to improve the consistency, verification, and validation of turbulence models within the aerospace community through a website database of verification and validation cases. Some of the variants of two widely-used turbulence models are described, and two independent computer codes (one structured and one unstructured) are used in conjunction with two specific versions of these models to demonstrate consistency with...

  6. Overview of the NASA Subsonic Rotary Wing Aeronautics Research Program in Rotorcraft Crashworthiness

    Jackson, Karen E.; Fuchs, Yvonne T.; Kellas, Sotiris
    This paper provides an overview of rotorcraft crashworthiness research being conducted at NASA Langley Research Center under sponsorship of the Subsonic Rotary Wing (SRW) Aeronautics Program. The research is focused in two areas: development of an externally deployable energy attenuating concept and improved prediction of rotorcraft crashworthiness. The deployable energy absorber (DEA) is a composite honeycomb structure, with a unique flexible hinge design that allows the honeycomb to be packaged and remain flat until needed for deployment. The capabilities of the DEA have been demonstrated through component crush tests and vertical drop tests of a retrofitted fuselage section onto different...

  7. Cytotoxic Effects of Re-Activated Lunar Dust Stimulant on Human Lung Cells

    Upadhyaya, Krishna
    Lunar dust has been of significant concern due to various problems observed on the Apollo missions. Reports from astronauts have shown that the dust may have caused eye and nasal irritation as well as possible hay fever like symptoms. As NASA hopes to go to the Moon within the next few years, we hope to understand the possible toxic effects the dust might have. In these studies, we are looking at the effect of "re-activated" lunar dust stimulant on human bronchial cells. A simple grinding analog as a method of simulating micrometeorite crushing on the moon is used to "activate"...

  8. Preparation and Properties of Nanocomposites from Pristine and Modified SWCNTs of Comparable Average Aspect Ratios

    Smith, Joseph G.; Haddon, R.; Connell, John W.; Watson, Kent A.; Yu, A.; Bekyarova, E.; Delozier, Donavon M.
    Low color, flexible, space-durable polyimide films with inherent and robust electrical conductivity to dissipate electrostatic charge (ESC) have been under investigation as part of a materials development activity for future NASA space missions. The use of single-walled carbon nanotubes (SWCNTs) is one means to achieving this goal. Even though the concentration of SWCNTs needed to achieve ESC dissipation is typically low, it is dependent upon purity, size, dispersion, and functionalization. In this study, SWCNTs prepared by the electric arc discharge method were used to synthesize nanocomposites using the LaRC(TradeMark) CP2 backbone as the matrix. Pristine and functionalized SWCNTs were mixed...

  9. A 16-yr Comparison of Fine Particle and Aerosol Strong Acidity at the Interface Zone (1,540 m) and Within (452 m) the Planetary Boundary Layer of the Great Gulf and Presidential-Dry River Class I Wildernesses on the Presidential Range, New Hampshire

    Wolfson, Jack M.; Doddridge, Bruce G.; Hill, Bruce; Seidel, Thomas M.; Murray, Georgia L.; Allen, George A.; Kimball, Kenneth
    Mount Washington, NH in the White Mountain National Forest, is flanked to the north-northeast and south by two Class I Wilderness areas, the Great Gulf and Presidential Range-Dry River Wildernesses, respectively. The Clean Air Act protects Class I area natural resource values from air pollution. Aerosol sulfate, a fine particulate component that is often transported long distances, is a known contributor to visibility degradation and acidic deposition. We examined summertime fine particulate aerosol mass and sulfate, strong acidity and ammonium concentrations from 1988 to 2004 on Mount Washington at two elevations, 452 and 1,540 meters (msl). The former site is...

  10. Effect of Lunar Dust Simulant on Human Epithelial Cell Lines

    Jeevarajan, Antony S.; Myers, Nicholas J.; Wallace, William T.
    The purpose of this project is to assess the potential toxicity of lunar dust to cause the release of pro-inflammatory cytokines by human lung cells. Some of this dust is on the scale of 1-2 micrometers and could enter the lungs when astronauts track dust into the habitat and inhale it. This could be a serious problem as NASA plans on going back to the moon for an extended period of time. Literature shows that quartz, which has a known cytoxicity, can cause acute cases of silicosis within 6 months, and in most cases cause silicosis after 3 years. The...

  11. Modulation by Hydrocortisone of the Free Amino Acid Pool and the Immune Response in Vitro

    Uchakin, Peter N.; Uchakina, Olga N.; Smith, Scott M.
    The main objective for this study was to assess changes in amino acid metabolism and immune response in a modeled "stress" environment. Heparinized blood samples from healthy donors were collected by venipuncture. Peripheral blood mononuclear cells were isolated and then incubated with a mixture of lipopolysaccharides and phytohemagglutinin in RPMI-1640 medium. Cell cultures were treated with hydrocortisone at physiological (10(exp -8) M, HCS-8) and "stress" (10(exp -6) M, HCS-6) concentrations. Surface expression of CD25 by T cells was analyzed at 24 hours by flow cytometry. Levels of the cytokines IL-2, IFN-gamma, IL-4, and IL-10 were measured at 48 hours with...

  12. Immune System Dysregulation during Spaceflight: Clinical Risk for Exploration-Class Missions

    Crucian, Brian; Sams, Clarence
    Spanning the last 30 years there have been a great many investigations of spaceflight effects on human immunity. Probably more than any other space life sciences discipline, there are many qualifiers when considering the published evidence. These include in-flight vs. ground analog studies, animal vs. human studies, studies on differing vehicles and mission durations, a myriad of immune cell subpopulations to monitor, and differing types of functional assays. These qualifiers aside, the current review by Gueguinou et al in this issue does an admirable job of summarizing the current knowledge base. The authors thoroughly describe the factors that will affect...

  13. All-Organic Actuator Fabricated with Single Wall Carbon Nanotube Electrodes

    Harrison, Joycelyn S.; Park, Cheol; Kang, Jinho; Park, Chan Eon; Lowther, Sharon E.
    Compliant electrodes to replace conventional metal electrodes have been required for many actuators to relieve the constraint on the electroactive layer. Many conducting polymers have been proposed for the alternative electrodes, but they still have a problem of poor thermal stability. This article reports a novel all-organic actuator with single wall carbon nanotube (SWCNT) films as the alternative electrode. The SWCNT film was obtained by filtering a SWCNT solution through an anodized alumina membrane. The conductivity of the SWCNT film was about 280 S/cm. The performance of the SWCNT film electrode was characterized by measuring the dielectric properties of NASA...

  14. Kinetics of Organic Matter Degradation in the Murchison Meteorite for the Evaluation of Parent Body Thermal History

    Kebukawa, Yoko; Nakashima, Satoru; Zolensky, Michael E.
    In order to evaluate kinetic parameters for thermal degradation of organic matter, in-situ heating experiments of bulk and insoluble organic matter (IOM) of Murchison (CM2) meteorite were conducted under micro FTIR combined with a heating stage. Decreases of aliphatic C-H band area under Ar flow were well fitted with Ginstling-Brounshtein three dimensional diffusion model, and the rate constants for decreases of aliphatic C-H were determined. Activation energies E(sub a), and frequency factors A obtained from these rate constants at different temperatures using the Arrhenius equation were E(sub a) = 109+/-3 kJ/mol and A = approx.8.7 x 10(exp 4)/s for IOM,...

  15. Orion Landing Simulation Eight Soil Model Comparison

    Mark, Stephen D.
    LS-DYNA finite element simulations of a rigid Orion Crew Module (CM) were used to investigate the CM impact behavior on eight different soil models. Ten different landing conditions, characterized by the combination of CM vertical and horizontal velocity, hang angle, and roll angle were simulated on the eight different soils. The CM center of gravity accelerations, pitch angle, kinetic energy, and soil contact forces were the outputs of interest. The simulation results are presented, with comparisons of the CM behavior on the different soils. The soils analyzed in this study can be roughly categorized as soft, medium, or hard, according...

  16. Errors in Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) Kinetic Temperature Caused by Non-Local Thermodynamic Equilibrium Model Parameters

    Garcia-Comas, Maya; Bermejo-Pantaleon, D.; Russell, James M.; Lopez-Puertas, M.; Gordley, L. L.; Mertens, Christopher J.; Marshall, Benjamin T.; Remsberg, Ellis E.; Funke, B.; Mlynczak, Martin G.
    The vast set of near global and continuous atmospheric measurements made by the SABER instrument since 2002, including daytime and nighttime kinetic temperature (T(sub k)) from 20 to 105 km, is available to the scientific community. The temperature is retrieved from SABER measurements of the atmospheric 15 micron CO2 limb emission. This emission separates from local thermodynamic equilibrium (LTE) conditions in the rarefied mesosphere and thermosphere, making it necessary to consider the CO2 vibrational state non-LTE populations in the retrieval algorithm above 70 km. Those populations depend on kinetic parameters describing the rate at which energy exchange between atmospheric molecules...

  17. Spectrally Resolved Flux Derived from Collocated AIRS and CERES Observations and its Application in Model Validation

    Yang, Wenze; Loeb, Norman G.; Ramaswamy, V.; Huang, Xianglei
    Spectrally resolved outgoing IR flux, the integrand of the outgoing longwave radiation (OLR), has its unique value in evaluating model simulations. Here we describe an algorithm of deriving such clear-sky outgoing spectral flux through the whole IR region from the collocated Atmospheric Infrared Sounder (AIRS) and the Clouds & the Earth's Radiant Energy System (CERES) measurements over the tropical oceans. Based on the scene types and corresponding angular distribution models (ADMs) used in the CERES Single Satellite Footprint (SSF) dataset, spectrally-dependent ADMs are developed and used to estimate the spectral flux at each AIRS channel. A multivariate linear prediction scheme...

  18. Induction of Micronuclei in Human Fibroblasts from the Los Alamos High Energy Neutron Beam

    Cox, Bradley
    The space radiation field includes a broad spectrum of high energy neutrons. Interactions between these neutrons and a spacecraft, or other material, significantly contribute to the dose equivalent for astronauts. The 15 degree beam line in the Weapons Neutron Research beam at Los Alamos Nuclear Science Center generates a neutron spectrum relatively similar to that seen in space. Human foreskin fibroblast (AG1522) samples were irradiated behind 0 to 20 cm of water equivalent shielding. The cells were exposed to either a 0.05 or 0.2 Gy entrance dose. Following irradiation, micronuclei were counted to see how the water shield affects the...

  19. Validity of the Aluminum Equivalent Approximation in Space Radiation Shielding

    Adams, Daniel O.; Wilson, John W.; Badavi, Francis F.
    The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space...

  20. International Space Station Research and Facilities for Life Sciences

    Robinson, Julie A.; Ruttley, Tara M.
    Assembly of the International Space Station is nearing completion in fall of 2010. Although assembly has been the primary objective of its first 11 years of operation, early science returns from the ISS have been growing at a steady pace. Laboratory facilities outfitting has increased dramatically 2008-2009 with the European Space Agency s Columbus and Japanese Aerospace Exploration Agency s Kibo scientific laboratories joining NASA s Destiny laboratory in orbit. In May 2009, the ISS Program met a major milestone with an increase in crew size from 3 to 6 crewmembers, thus greatly increasing the time available to perform on-orbit...

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