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  • 1
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    Sakata-Taketani spin-0 theory with external field interactions - Lagrangian formalism and causal properties (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: To illustrate that a relativistic field theory need not be manifestly covariant, Lorentz-invariant Lagrangian densities are constructed that yield the equation satisfied by an interacting (two-component) Sakata-Taketani spin-0 field. Six types of external field couplings are considered, two scalars, two vectors, an antisymmetric second-rank tensor, and a symmetric second-rank tensor, with the results specialized to electromagnetic interactions. For either of the two second-rank couplings, the equation is found to describe noncausal wave propagation, a property that is apparent from the dependence of the coefficients of the space derivatives on the external field; in contrast, the noncausality of the corresponding manifestly covariant Duffin-Kemmer-Petiau spin-0 equation is not so obvious. The possibilities for generalizing the results to higher spin theories involving only the essential 2(2J + 1) components for a particle with a definite spin J and mass m are discussed in considerable detail.
    Keywords: NUCLEAR AND HIGH-ENERGY PHYSICS
    Type: Annals of Physics; 104; Apr. 197
    Format: text
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  • 2
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    Noncausal effects in relativistic wave equations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Manifestly covariant wave equations describing particles with a unique mass and spin can, for certain types of external-field interactions, possess noncausal solutions. The paper reports a procedure for applying Pierce decomposition of all six couplings expressed in the Duffin-Kemmer-Petiau spin-0 formula. This treatment converts the equation to a form in which the causal properties are apparent. The conditions under which the causal properties of higher-spin equations can be made manifest are discussed.
    Keywords: NUCLEAR AND HIGH-ENERGY PHYSICS
    Type: Nuovo Cimento; vol. 18
    Format: text
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  • 3
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    Noncausal propagation in spin-0 theories with external field interactions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The two-component Sakata-Taketani (ST) spin-0 theory and the single-component Klein-Gordon theory are obtained from the five-component Duffin-Kemmer-Petiau (DKP) theory with six types of external field interactions by means of a Peirce decomposition. Whereas the DKP equation manifests the covariance, the ST equation manifests the causal properties. In particular, the presence of noncausal wave propagation when there is coupling to a second-rank tensor field is apparent from the form of the ST equation, in which the coefficients of all the space derivatives depend on the external field. The results indicate that the causal properties of higher-spin equations should also be obvious when they are expressed in 2(2J + 1)-component Schroedinger form
    Keywords: NUCLEAR AND HIGH-ENERGY PHYSICS
    Type: Physical Review D - Particles and Fields; vol. 15
    Format: text
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  • 4
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    Neutrino tomography - Tevatron mapping versus the neutrino sky (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The feasibility of neutrino tomography of the earth's interior is discussed, taking the 80-GeV W-boson mass determined by Arnison (1983) and Banner (1983) into account. The opacity of earth zones is calculated on the basis of the preliminary reference earth model of Dziewonski and Anderson (1981), and the results are presented in tables and graphs. Proposed tomography schemes are evaluated in terms of the well-posedness of the inverse-Radon-transform problems involved, the neutrino generators and detectors required, and practical and economic factors. The ill-posed schemes are shown to be infeasible; the well-posed schemes (using Tevatrons or the neutrino sky as sources) are considered feasible but impractical.
    Keywords: NUCLEAR AND HIGH-ENERGY PHYSICS
    Type: Nature (ISSN 0028-0836); 309; 38-42
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  • 5
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    A comparison of high resolution radio and far-infrared maps of M 17 (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: New 3.5-cm radio and 69-micron far-infrared maps of M17, both made with an angular resolution of about 1.5 arcmin, are presented. Each map has three distinct maxima. Two of the maxima on the far-IR map agree in position with the corresponding maxima on the radio map. However, the positions of the brightest peak in the radio and far-infrared maps, located in the SW part of M17, differ by 4.6 + or - 2.2 s in right ascension and +44 + or - 20 sec in declination, with the far-infrared peak lying between the radio peak and the dense molecular cloud southwest of the H II region. It is believed that the positional offset of the radio and far-infrared peak is physically significant. The origin of the far-infrared radiation appears to be thermal emission from dust at the interface of the ionized gas and molecular cloud. This interface region is probably heated by radiation from the H II region.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 76; 1, Ju; June 197
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  • 6
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    Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 2: User's manual (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A user's manual which describes input/output routines and recommended operating procedures relating to MAPSEP is presented. Samples runs are included.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143935
    Format: application/pdf
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  • 7
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    Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 1: Analytical manual (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The mission analysis program for solar electric propulsion (MAPSEP) is comprised of the basic modes: TOPSEP (trajectory generation), GODSEP (linear error analysis), and SIMSEP (simulation). The program is designed to analyze any low thrust mission with respect to trajectory performance, guidance and navigation, and to provide system related requirements for the purpose of vehicle design. The MAPSEP organization is described along with all models and algorithms. Topics discussed include: trajectory and error covariance propagation methods, orbit determination processes, thrust modeling, and trajectory correction (guidance) schemes.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143934
    Format: application/pdf
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  • 8
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    Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 3: Program manual (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The internal structure of MAPSEP is described. Topics discussed include: macrologic, variable definition, subroutines, and logical flow. Information is given to facilitate modifications to the models and algorithms of MAPSEP.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143936
    Format: application/pdf
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  • 9
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    Application of small-signal modeling and measurement techniques to the stability analysis of an integrated switching-mode power system (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Small-signal modeling techniques are used in a system stability analysis of a breadboard version of a complete functional electrical power system. The system consists of a regulated switching dc-to-dc converter, a solar-cell-array simulator, a solar-array EMI filter, battery chargers and linear shunt regulators. Loss mechanisms in the converter power stage, including switching-time effects in the semiconductor elements, are incorporated into the modeling procedure to provide an accurate representation of the system without requiring frequency-domain measurements to determine the damping factor. The small-signal system model is validated by the use of special measurement techniques which are adapted to the poor signal-to-noise ratio encountered in switching-mode systems. The complete electrical power system with the solar-array EMI filter is shown to be stable over the intended range of operation.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: PESC ''80; Power Electronics Specialists Conference; Jun 16, 1980 - Jun 20, 1980; Atlanta, GA
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  • 10
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    NGC 2024: Multi-wavelength Infrared and Radio Observations (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of far-infrared maps obtained on the KAO find the total IR luminosity of NGC 2024 is to the 4th power L, and show a peak in flux density and optical depth about 1' south of IRS 2. High resolution spectra of IRS 2 in Brackett alfa and Pfund gamma indicate the presence of an optically thick wind with M approx. 7 x 10 to the minus 7 power M sub yr to minus 1 power, from which we infer that IRS 2 is unable to supply the luminosity observed. A six centimeter continuum map peaks near the location of the far-infrared peak and confirms it as a likely site for a source to provide this luminosity. Maps in HCN, CS, and H2CO show the gas is dense in the direction of the far IR peak. Velocity analysis shows the H2 region created by the far IR source and IRS 2 forms an expanding bubble in front of which the H2CO is seen in absorption, and which is bounded in the south and behind by dense material.
    Keywords: ASTRONOMY
    Type: NASA. Ames Research Center Airborne Astron. Symp.; p 164-171
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