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  • 1
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    Monte Carlo approach in assessing damage in higher order structures of DNA (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We have developed a computer monitor of nuclear DNA in the form of chromatin fibre. The fibres are modeled as a ideal solenoid consisting of twenty helical turns with six nucleosomes per turn. The chromatin model, in combination with are Monte Carlo theory of radiation damage induces by charged particles, based on general features of tack structure and stopping power theory, has been used to evaluate the influence of DNA structure on initial damage. An interesting has emerged from our calculations. Our calculated results predict the existence of strong spatial correlations in damage sites associated with the symmetries in the solenoidal model. We have calculated spectra of short fragments of double stranded DNA produced by multiple double strand breaks induced by both high and low LET radiation. The spectra exhibit peaks at multiples of approximately 85 base pairs (the nucleosome periodicity), and approximately 1000 base pairs (solenoid periodicity). Preliminary experiments to investigate the fragment distributions from irradiated DNA, made by B. Rydberg at Lawrence Berkeley Laboratory, confirm the existence of short DNA fragments and are in substantial agreement with the predictions of our theory.
    Keywords: Life Sciences (General)
    Type: Basic life sciences (ISSN 0090-5542); Volume 63; 225-35; discussion 235-41
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  • 2
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    Information transfer from DNA to peptide nucleic acids by template-directed syntheses (1997)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Peptide nucleic acids (PNAs) are analogs of nucleic acids in which the ribose-phosphate backbone is replaced by a backbone held together by amide bonds. PNAs are interesting as models of alternative genetic systems because they form potentially informational base paired helical structures. Oligocytidylates have been shown to act as templates for formation of longer oligomers of G from PNA G2 dimers. In this paper we show that information can be transferred from DNA to PNA. DNA C4T2C4 is an efficient template for synthesis of PNA G4A2G4 using G2 and A2 units as substrates. The corresponding synthesis of PNA G4C2G4 on DNA C4G2C4 is less efficient. Incorporation of PNA T2 into PNA products on DNA C4A2C4 is the least efficient of the three reactions. These results, obtained using PNA dimers as substrates, parallel those obtained using monomeric activated nucleotides.
    Keywords: Exobiology
    Type: Nucleic acids research (ISSN 0305-1048); Volume 25; 23; 4792-6
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  • 3
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    Information transfer from peptide nucleic acids to RNA by template-directed syntheses (1997)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Peptide nucleic acids (PNAs) are uncharged analogs of DNA and RNA in which the ribose-phosphate backbone is substituted by a backbone held together by amide bonds. PNAs are interesting as models of alternative genetic systems because they form potentially informational base paired helical structures. A PNA C10 oligomer has been shown to act as template for efficient formation of oligoguanylates from activated guanosine ribonucleotides. In a previous paper we used heterosequences of DNA as templates in sequence-dependent polymerization of PNA dimers. In this paper we show that information can be transferred from PNA to RNA. We describe the reactions of activated mononucleotides on heterosequences of PNA. Adenylic, cytidylic and guanylic acids were incorporated into the products opposite their complement on PNA, although less efficiently than on DNA templates.
    Keywords: Exobiology
    Type: Nucleic acids research (ISSN 0305-1048); Volume 25; 23; 4797-802
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  • 4
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    HIGH-SPEED MOTION PICTURE STUDIES OF FLOW IN A CAVITATING VENTURI. INTERNAL REPORT 12 (1962)
    In:  CASI
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    Publication Date: 2006-10-26
    Description: High-speed motion picture studies of flow in a cavitating venturi
    Keywords: FACILITIES, RESEARCH, AND SUPPORT
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  • 5
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    Sequence dependent N-terminal rearrangement and degradation of peptide nucleic acid (PNA) in aqueous solution (1998)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The stability of the PNA (peptide nucleic acid) thymine monomer inverted question markN-[2-(thymin-1-ylacetyl)]-N-(2-aminoaminoethyl)glycine inverted question mark and those of various PNA oligomers (5-8-mers) have been measured at room temperature (20 degrees C) as a function of pH. The thymine monomer undergoes N-acyl transfer rearrangement with a half-life of 34 days at pH 11 as analyzed by 1H NMR; and two reactions, the N-acyl transfer and a sequential degradation, are found by HPLC analysis to occur at measurable rates for the oligomers at pH 9 or above. Dependent on the amino-terminal sequence, half-lives of 350 h to 163 days were found at pH 9. At pH 12 the half-lives ranged from 1.5 h to 21 days. The results are discussed in terms of PNA as a gene therapeutic drug as well as a possible prebiotic genetic material.
    Keywords: Exobiology
    Type: Nouveau journal de chimie (ISSN 0398-9836); Volume 22; 1055-9
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  • 6
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    Impact of changing fuel characteristics on supersonic cruise airplane (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The question of an advanced supersonic cruise research airplane is related to future oil supplies and prices. Technical data on the impact of changing fuel characteristics on the SCR airplane were developed. Projections of crude oil characteristics typical of the 1985 to 2000 time period were made with the help of consultants to the oil industry. Refineries for the future were modeled to establish jet fuel of engine and aircraft systems for future airplanes, with emphasis on supersonic cruise airplanes. Study results do not show a need for broadening the fuel specification. Hypothetical study fuels with broader specifications were defined, however, as was the impact of their properties on the SCR airplane and systems.
    Keywords: PROPELLANTS AND FUELS
    Type: NASA. Langley Research Center Supersonic Cruise Res., 1979, Pt. 2; p 855-872
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  • 7
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    End-wall boundary layer measurements in a two-stage fan (1983)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Detailed flow measurements made in the casing boundary layer of a two-stage transonic fan are summarized. These measurements were taken at stations upstream of the fan, between all blade rows, and downstream of the last blade row. At the design tip speed of 429 m/sec the fan achieved a peak efficiency of 0.846 at a pressure ratio of 2.471. The boundary layer data were obtained at three weight flows at the design speed: one near choke flow, one near peak efficiency, and one near stall. Conventional boundary layer parameters were calculated from the data measured at each measuring station for each of the three flows. A classical two dimensional casing boundary layer was measured at the fan inlet and extended inward to approximately 15 percent of span. A highly three dimensional boundary layer was measured at the exit of each blade row and extended inward to approximately 10 percent of span. The steep radial gradient of axial velocity noted at the exit of the rotors was reduced substantially as the flow passed through the stators. This reduced gradient is attributed to flow mixing. The amount of flow mixing was reflected in the radial redistribution of total temperature as the flow passed through the stators. The data also show overturning of the tip flow at the stator exits that is consistent with the expected effect of the secondary flow field. The blockage factors calculated from the measured data show an increase in blockage across the rotors and a decrease across the stators.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Viscous Effects in Turbomachines; 23 p
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  • 8
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    CME Flux Rope and Shock Identifications and Locations: Comparison of White Light Data, Graduated Cylindrical Shell Model, and MHD Simulations (2016)
    In:  Other Sources
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    Publication Date: 2017-04-15
    Description: Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the graduated cylindrical shell (GCS) model to fit a flux rope to the CME directed toward STEREO A after about 19:00 UT on 29 November 2013 and check the quality of the heliocentric distance-time evaluations by carrying out a three-dimensional magnetohydrodynamic (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the CME and shock leading edges are determined from the simulated white light images and magnetic field strength data. We find very good agreement between the predicted and observed heliocentric distances, showing that the GCS model and the BATS-R-US simulation approach work very well and are consistent. In order to assess the validity of CME and shock identification criteria in coronagraph images, we also compute synthetic white light images of the CME and shock. We find that the outer edge of a cloud-like illuminated area in the observed and predicted images in fact coincides with the leading edge of the CME flux rope and that the outer edge of a faint illuminated band in front of the CME leading edge coincides with the CME-driven shock front.
    Keywords: Solar Physics
    Type: GSFC-E-DAA-TN40667 , Journal of Geophysical Research: Space Physics (e-ISSN 2169-9402); Volume 121; Issue 3; 1886-1906
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  • 9
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    CIR Morphology, Turbulence, Discontinuities, and Energetic Particles (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns of turbulence and energetic particles.
    Type: Space Science Reviews
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  • 10
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    An experimental study of the behavior of liquid streams injected into a low-pressure chamber (1949)
    In:  CASI
    Details
    Publication Date: 2019-05-31
    Keywords: unknown
    Type: JPL-PR-4-94
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