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  • Life and Medical Sciences  (9,859)
  • SPACE RADIATION
  • 1990-1994  (8,943)
  • 1960-1964  (1,326)
  • 1945-1949  (453)
  • 1930-1934  (365)
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  • 1
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    Voyager measurements of the isotopic composition of cosmic-ray aluminum and implications for the propagation of cosmic rays (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We report a new measurement of the cosmic-ray isotopic composition of aluminum in the low-energy range form 75 to 206 MeV per nucleon.This measurement was made using the high-energy telescope of the CRS experiment on the Voyager 1 and 2 spacecraft during the time period from 1977 to 1993 with an average solar modulation level about 497 MV, roughly the same as at Earth near sunspot minimum. We obtain approximately 430 Al events of which approximately 35 are Al-26 and 395 are Al-27. The Al isotopes were separated with an average mass resolution sigma of 0.35 amu. Our interpretation of the isotopic composition of cosmic-ray aluminum is based on a standard Leaky-Box model for the interstellar propagation of cosmic-ray nuclei using the latest cross sections of the New Mexico-Saclay collaboration as well as a disk-halo diffusion model. From our observed ratio Al-26/Al-27 of 8.3 +/- 2.4 % we deduce an average interstellar density of about 0.52 (+0.26, -0.2) atoms per cu cm. This density is larger than the value of 0.28 (+0.14, -0.11) atoms per cu cm we found from an analysis of the observed abundance of the longer lived Be-10 made using data from the Voyager detectors over almost the same time interval and using essentially the same propagation program.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 430; 1; p. L69-L72
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  • 2
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    SOFIP-A SHORT ORBITAL FLUX INTEGRATION PROGRAM (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The Short Orbital Flux Integration Program, SOFIP, was developed to provide a fast and accurate evaluation of the space radiation environment expected to be encountered by geocentric satellites. SOFIP uses Vette's standardized models of the terrestrial trapped particle environment in performing the evaluation. For a given trajectory, the basic analysis involves the calculation of the composite integral orbit spectrum of either protons or electrons. Additional calculations which may be performed include exposure index, peaks per orbit, percent time in electron trapping zones, differential spectrum, and solor proton fluences. The results of the SOFIP calculations should provide the analyst with a detailed picture of the radiation environment in which the vehicle will operate. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 computer with a central memory requirement of approximately 60K of 8 bit bytes. The SOFIP program was developed in 1979.
    Keywords: SPACE RADIATION
    Type: GSC-12554
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  • 3
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    Galactic cosmic ray modulation and interplanetary medium perturbations due to a long-living active region during October 1989 (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: During October 1989, three very energetic flares were ejected by the same active region at longitudes 9 deg E, 32 deg W, and 57 deg W, respectively. The shape of the galactic cosmic ray variations suggests the presence of large magnetic cloud structures (Nagashima et al., 1990) following the shock-associated perturbations. In spite of long data gaps the interplanetary observations at Interplanetary Monitoring Platform (IMP) 8 (near the Earth) and International Cometary Explorer (ICE)(approximately 1 AU, approximately 65 deg W) confirm this possibility for the event related to the 9 deg E flare; the principal axes analysis shows that the interplanetary magnetic field variations at both spacecraft locations are mainly confined on a meridian plane. This result suggests that the western longitudinal extension of this cloud is indeed very large (greater than or equal to 5 deg). The nonnegligible depression in the cosmic ray intensity observed inside the possible cloud related to the 57 deg W flare indicates that also the eastern extension could be very wide. The analysis of neutron monitor data shows clearly the cosmic ray trapping effect of magnetic clouds; this mechanism seems to be responsible for the enhanced diurnal effect often observed during the recovery phase of Forbush decreases. We give an interpretation for the anisotropic cosmic ray peak occurring in the third event, and, related to that, we suggest that the Forbush decrease modulated region at the Earth's orbit could be somewhat wider than the magnetic cloud, as already anticipated by Nagashima et al. (1990). By this analysis, based mainly on cosmic ray data, we show that it is possible to do reasonable inferences on the large-scale structure of flare-related interplanetary perturbations when interplanetary medium data are not completely present.
    Keywords: SPACE RADIATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A3; p. 4227-4234
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  • 4
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    The blazar gamma-ray luminosity function and the diffuse extragalactic gamma-ray background (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We have used the data from the new EGRET catalog on 'grazars' (blazers which are observed to be high-energy gamma-ray sources), together with radio data, to construct a new relation between radio and gamma-ray luminosity for these sources. Using this relation to construct a grazar gamma-ray luminosity function, we then calculate the contribution of unresolved grazars to the cosmic gamma-ray background radiation. We derive the energy spectrum of this background component above 100 MeV and the angular fluctuations in this background implied by our model.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 430; 1; p. L21-L24
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  • 5
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    Compton scattering in jets: A mechanism for approximately 0.4 and less than or approximately 0.2 MeV line production (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We show that gamma-ray line emission at approximately 0.4 and less than or approximately 0.2 MeV can be produced by Compton scattering of beamed radiation in the jets of Galactic black hole candidates. This mechanism has the novel feature of not invoking the presence of e(exp +)-e(exp -) pairs. To produce the two lines, we employ a symmetric double-sided jet with bulk flow velocity of about 0.5c and incident beam radiation with a hard energy spectrum. We show that the two lines can be seen at viewing-angle cosines relative to the jet ranging from 0.2 to 0.6. This comprises 40% of the total solid angle. In addition, the line radiation is approximately 10% polarized. Depending on the bulk flow and viewing angle, the model can produce lines at other energies as well. In particular, a broad feature near 1 MeV can be seen by viewing the jet close to its axis. Our model can also accommodate single-line spectra if the beamed gamma-ray emission or the jets themselves are asymmetric.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 431; 1; p. L39-L42
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  • 6
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    The isotopic composition of cosmic-ray beryllium and its implication for the cosmic ray's age (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We report a new measurement of the cosmic-ray isotopic composition of beryllium in the low-energy range from 35 to 113 MeV per nucleon. This measurement was made using the High Energy Telescope of the CRS experiment on the Voyager 1 and 2 spacecraft during the time period from 1977 to 1991. In this overall time period of 14 years the average solar modulation level was about 500 MV. The cosmic-ray beryllium isotopes were completely separated with an average mass resolution sigma of 0.185 amu. The isotope fractions of Be-7, Be-9, and Be-10 obtained are 52.4 +/- 2.9%, 43.3 +/- 3.7%, and 4.3 +/- 1.5%, respectively. The measured cosmic-ray abundances of Be-7 and Be-9 are found to be in agreement with calculations based on standard Leaky-Box model for the interstellar propagation of cosmic-ray nuclei using the recent cross sections of the New Mexico-Saclay collaboration. From our observed ratio Be-10/Be = 4.3 +/- 1.5% we deduce an average interstellar density of about 0.28 (+0.14, -0.11) atoms/cu cm, and acosmic-ray lifetime for escape of 27 (+19, -9) x 10(exp 6) years. The surviving fraction of Be-10 is found to be 0.19 +/- 0.07. Modifications to the conclusions of the Leaky-Box model when a diffusion + convection halo model for propagation is used are also considered.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 423; 1; p. 426-431
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  • 7
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    Can a variable alpha induce limit cycle behavior and exponential luminosity decay in transient soft x ray sources? (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: There has been, recently, a revival of the stability problem of accretion disks. Much of this renewed interest is due to recent observational data on transient soft X-ray novae, which are low-mass X-ray binaries. It is widely believed that nonsteady mass transfer from the secondary onto the compact primary, through an accretion disk, is the reason for the observed spectacular events in the form of often repetitive outbursts, with recurrence times ranging from 1 to 60 yr and duration time on the scale of months. Though not having reached yet a consensus about the nature of the mechanism that regulates the mass transfer, the disk thermal instability model seems to be favored by the fact that the rise in the hard X-ray luminosity is prior to the rise in the soft X-ray luminosity, while the mass transfer instability model seems to be hindered by the fact that the luminosity during quiescence is unable to trigger the thermal instability. However, it should be stressed that, remarkably, the X-ray light curves of these X-ray novae all show overall exponential decays, a feature quite difficult to reproduce in the framework of the viscous disk model, which yields powerlike luminosity decay. Taking into account this observational constraint, we have studied the temporal evolution of perturbations in the accretion rate, under the assumption that alpha is radial and parameter dependent. The chosen dependence is such that the model can reproduce limit cycle behavior (the system is locally unstable but globally stable). However, the kind of dependence we are looking for in alpha does not allow us to use the usual Shakura and Sunyaev procedure in the sense that we no longer can obtain a linearized continuity equation without explicit dependence on the accretion rate. This is so because now we cannot eliminate the accretion rate by using the angular momentum conservation equation.
    Keywords: SPACE RADIATION
    Type: Lunar and Planetary Inst., Workshop on Physics of Accretion Disks Around Compact and Young Stars; p 3-4
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  • 8
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    Long-term modulation of galactic cosmic radiation and its model for space exploration (1994)
    In:  Other Sources
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    Publication Date: 2019-04-02
    Description: As the human exploration of space has received new attention in the United States, studies find that exposure to space radiation could adversely impact the mission design. Galactic Cosmic Radiation (GCR), with its very wide range of charges and energies, is particularly important for a mission to Mars, because it imposes a stiff mass penalty for spacecraft shielding. Dose equivalent versus shielding thickness calculations, show a rapid initial drop on exposure with thickness, but an asymptotic behavior at a higher shielding thickness. Uncertainties in the radiobiology are largely unknown. For a fixed radiation risk, this leads to large uncertainties in shielding thickness for small uncertainties in estimated dose. In this paper we investigate the application of steady-state, spherically-symmetric diffusion-convection theory of solar modulation to individual measurements of differential energy spectra from 1954 to 1989 in order to estimate the diffusion coefficient, kappa(r,t), as a function of time. We have correlated the diffusion coefficient to the Climax neutron monitor rates and show that, if the diffusion coefficient can be separated into independent functions of space and time: kappa(r,t)=K(t) k(sub 0) beta Pk(sub 1) (r), where beta is the particle velocity and P the rigidity, then (i) The time dependent quantity 1/K(t), which is proportional to the deceleration potential, phi(r,t), is linearly related to the Climax neutron monitor counting rate. (ii) The coefficients obtained from hydrogen or helium intensity measurements are the same. (iii) There are different correlation functions for odd and even solar cycles. (iv) The correlation function for the Climax neutron monitor counting rate for given time, t, can be used to estimate mean deceleration parameter phi(t) to within +/- 15% with 90% confidence. We have shown that k(r,t) determined from hydrogen and/or helium data, can be used to fit the oxygen and iron differential energy spectra with a root mean square error of about +/- 10%, and essentially independent of the particle charge or energy. We have also examined the ion chamber and C-14 measurements which allow the analysis to be extended from the year 1906 to 1990. Using this model we have defined reference GCR spectra at solar minimum and solar maximum. These can be used for space exploration studies and provide a quantitative estimate of the error in dose due to changes in GCR intensities.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 749-757
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  • 9
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    Proton flare and magnetic storm effect in the vicinity of the Earth (1994)
    In:  Other Sources
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    Publication Date: 2019-04-02
    Description: We have developed a model and associated computational procedure for estimating energetic proton exposures during a major solar proton event that occur in combination with a large magnetic storm. Transmission functions for solar protons are computed using geomagnetic vertical cutoff data for quiescent amd disturbed conditions. Predicted exposures in low altitude polar orbit are found to be orders of magnitude greater for severe magnetic storm conditions than are corresponding exposures in the absence of major disturbances. We examine the response scenario for the events of November 1960 as an example.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 655-660
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  • 10
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    Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter (1994)
    In:  Other Sources
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    Publication Date: 2019-04-02
    Description: Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 923-926
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  • 11
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    Solar modulation and nuclear fragmentation effects in galactic cosmic ray transport through shielding (1994)
    In:  Other Sources
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    Publication Date: 2019-04-02
    Description: Crews of manned interplanetary missions may accumulate significant radiation exposures from the Galactic Cosmic Ray (GCR) environment in space. Estimates of how these dose levels are affected by the assumed temporal and spatial variations in the composition of the GCR environment, and by the effects of the spacecraft and body self-shielding on the transported fields are presented. In this work, the physical processes through which shielding alters the transported radiation fields are described. We then present estimates of the effects on model calculations of (1) nuclear fragmentation model uncertainties, (2) solar modulation, (3) variations between solar cycles, and (4) proposed changes to the quality factors which relate dose equivalent to absorbed dose.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 853-861
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  • 12
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    Channel to energy calibration results for the BATSE large area detectors (1994)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: Continuum 16 channel spectra obtained from in flight data are used to identify and correct for nonlinearities in the channel-to-energy conversion algorithm for the BATSE large area detectors. The Crab Nebula spectra obtained by the BATSE earth occultation technique are used to characterize any nonlinearities inherent in the low energy channel bin widths on a detector by detector basis. The bin widths are optimized to remove distortions from observed gamma ray spectra. The recalibrated bin edges are used in an analysis of Crab Pulsar data to verify the improvements in the calibration.
    Keywords: SPACE RADIATION
    Type: Alabama Univ., BATSE Data Analysis; 1 p
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  • 13
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    Balloon-borne measurements of the SN1987A hard x ray continuum (1994)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: SN1987A hard x ray continuum spectra obtained on 29 Oct. 1987, 9-10 Apr. 1988, and 11 Nov. 1988, from balloon flight measurements are presented. The spectra, spanning the energy range from 25 keV to 300 keV, were analyzed using a detector response matrix inversion technique that converts the spectra from counts/sec-sq cm-kev to photons/sec-sq cm-kev allowing direct comparison with theoretical models. The results indicate that the bulk of the Co-56 is mixed moderately through the inner regions of the SN envelope but they do not preclude the mixing of a small amount of the Co-56 further out into the envelope necessary to account for the observed Co-56 line fluxes. The effect of the ratio of Co-57 to Co-56 on the 11 Nov. 1988, continuum spectrum is discussed.
    Keywords: SPACE RADIATION
    Type: Alabama Univ., BATSE Data Analysis; 1 p
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  • 14
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    A study of gamma ray burst continuum properties presnting evidence for two spectral states in bursts (1994)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: Evidence is presented for the existence of two spectral states contributing simultaneously to the total spectrum observed in many gamma-ray bursts (GRB's). An ensemble of 120 GRB's measured by BATSE were studied, using 4 channel spectral data, to determine in which bursts the spectral states can be most effectively resolved. The technique of summing the low intensity spectra together to get an average spectrum allows for precise characterization of the average low intensity spectral behavior. The 4 and 16 channel spectra obtained by the BATSE Large Area Detectors (LAD's) are analyzed using a model-independent spectral inversion technique. The results of these analyses applied to an individual burst are discussed in detail.
    Keywords: SPACE RADIATION
    Type: Alabama Univ., BATSE Data Analysis; 1 p
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  • 15
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    Continuum spectral characteristics of bursts measured with BATSE large area detectors (1994)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: The continuum spectra of bursts are studied with particular emphasis placed on the search for spectral subcomponents. The spectra observed in individual bursts show significant evolution throughout their durations. The degree to which hard and soft spectra are combined in bursts and the effect this has on the complexity of the observed spectra are addressed. In particular the presence of broad cusps in spectra in the 50-100 keV range are studied to determine both the degree to which these features are present in the LAD data and whether superposition of hard and soft spectra simultaneously can account for them. Also the time histories of the power output (ergs/sec) from bursts are studied to investigate the dynamic coupling between hard and soft spectra in bursts as a probe of the autonomy of the hard and soft emission mechanisms.
    Keywords: SPACE RADIATION
    Type: Alabama Univ., BATSE Data Analysis; 1 p
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  • 16
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    The continuum spectral characteristics of gamma ray bursts observed by BATSE (1994)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: Distributions of the continuum spectral characteristics of 260 bursts in the first Burst and Transient Source Experiment (BATSE) catalog are presented. The data are derived from flux ratios calculated from the BATSE Large Area Detector (LAD) four channel discriminator data. The data are converted from counts to photons using a direct spectral inversion technique to remove the effects of atmospheric scattering and the energy dependence of the detector angular response. Although there are intriguing clusterings of bursts in the spectral hardness ratio distributions, no evidence for the presence of distinct burst classes based on spectral hardness ratios alone is found. All subsets of bursts selected for their spectral characteristics in this analysis exhibit spatial distributions consistent with isotropy. The spectral diversity of the burst population appears to be caused largely by the highly variable nature of the burst production mechanisms themselves.
    Keywords: SPACE RADIATION
    Type: Alabama Univ., BATSE Data Analysis; 1 p
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  • 17
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    Why galactic gamma-ray bursts might depend on environment: Blast waves around neutron stars (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Although galactic models for gamma-ray bursts are hard to reconcile with the isotropy data, the issue is still sufficiently open that both options should be explored. The most likely 'triggers' for bursts in our Galaxy would be violent disturbances in the magnetospheres of neutron stars. Any event of this kind is likely to expel magnetic flux and plasma at relativistic speed. Such ejecta would be braked by the interstellar medium (ISM), and a gamma-ray flash may result from this interaction. The radiative efficiency, of this mechanism would depend on the density of the circumstellar ISM. Therefore, even if neutron stars were uniformly distributed in space (at least within 1-2 kpc of the Sun), the observed locations of bursts would correlate with regions of above-average ISM density.
    Keywords: SPACE RADIATION
    Type: NASA-CR-199556 , NAS 1.26:199556 , NIPS-95-05571
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  • 18
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    Do gamma-ray burst sources repeat? (1994)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al. 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic ad the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the bursts cannot be excluded.
    Keywords: SPACE RADIATION
    Type: NASA-TM-110835 , NAS 1.15:110835
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  • 19
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    X-rays from the youngest stars (1994)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The X-ray properties of classical and weak-lined T Tauri stars are briefly reviewed, emphasizing recent results from the ROSAT satellite and prospects for ASCA. The interpretation of the high level of T Tauri X-rays as enhanced solar-type magnetic activity is discussed and criticized. The census of X-ray emitters is significantly increasing estimates of galactic star formation efficiency, and X-ray emission may be important for self-regulation of star formation. ASCA images will detect star formation regions out to several kiloparsecs and will study the magnetically heated plasma around T Tauri stars. However, images will often suffer from crowding effects.
    Keywords: SPACE RADIATION
    Type: NASA-CR-199555 , NIPS-95-05570 , NAS 1.26:199555
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  • 20
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    Discovery of intense gamma-ray flashes of atmospheric origin (1994)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Observations have been made of a new terrestrial phenomenon: brief (approx. millisecond), intense flashes of gamma rays, observed with space-borne detectors. These flashes must originate at altitudes in the atmosphere above at least 30 km in order to be observable by orbiting detectors aboard the Compton Gamma-Ray Observatory (CGRO). At least a dozen events have been detected over the past 2 years. The photon spectra from the events are very hard and are consistent with bremsstrahlung emission from energetic (MeV) electrons. The most likely origin of these high energy electrons, while speculative at this time, is a rare type of high altitude electrical discharge above thunderstorm regions.
    Keywords: SPACE RADIATION
    Type: NASA-TM-110853 , NAS 1.15:110853
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  • 21
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    Theoretical and experimental studies relevant to interpretation of auroral emissions (1994)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: This report describes the accomplishments of a program designed to develop the tools necessary to interpret auroral emissions measured from a space-based platform. The research was divided into two major areas. The first area was a laboratory study designed to improve our understanding of the space vehicle external environment and how it will affect the space-based measurement of auroral emissions. Facilities have been setup and measurements taken to simulate the gas phase environment around a space vehicle; the radiation environment encountered by an orbiting vehicle that passes through the Earth's radiation belts; and the thermal environment of a vehicle in Earth orbit. The second major area of study was a modeling program to develop the capability of using auroral images at various wavelengths to infer the total energy influx and characteristic energy of the incident auroral particles. An ab initio auroral calculation has been added to the extant ionospheric/thermospheric global modeling capabilities within our group. Once the addition of the code was complete, the combined model was used to compare the relative intensities and behavior of various emission sources (dayglow, aurora, etc.). Attached papers included are: 'Laboratory Facility for Simulation of Vehicle-Environment Interactions'; 'Workshop on the Induced Environment of Space Station Freedom'; 'Radiation Damage Effects in Far Ultraviolet Filters and Substrates'; 'Radiation Damage Effects in Far Ultraviolet Filters, Thin Films, and Substrates'; 'Use of FUV Auroral Emissions as Diagnostic Indicators'; and 'Determination of Ionospheric Conductivities from FUV Auroral Emissions'.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196032 , NAS 1.26:196032
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  • 22
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    Effects of isotope selection on solution convergence in HZE transport (1994)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A fragmenting iron ion produces hundreds of isotopes during nuclear reactions. These isotopes are represented in the solution of the transport problem. A reduced set of isotopes is selected to minimize the computational burden but introduces error in the final result. A minimum list of 122 isotopes is required for adequate representation of the mass and charge distributions of the secondary radiation fields. A reduced set of 80 isotopes is sufficient to represent the charge distribution alone and represents reasonably well the linear energy transfer properties of the iron beam. Because iron fragmentation produces nearly every isotope lighter than iron, the resulting 122-isotope list should be adequate for ion beams with charges equal to or less than 26.
    Keywords: SPACE RADIATION
    Type: NASA-TP-3445 , L-17357 , NAS 1.60:3445
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  • 23
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    Convection and electrodynamic signatures in the vicinity of a Sun-aligned arc: Results from the Polar Acceleration Regions and Convection Study (Polar ARCS) (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental campaign designed to study high-latitude auroral arcs was conducted in Sondre Stromfjord, Greenland, on February 26, 1987. The Polar Acceleration Regions and Convection Study (Polar ARCS) consisted of a coordinated set of ground-based, airborne, and sounding rocket measurements of a weak, sun-aligned arc system within the duskside polar cap. A rocket-borne barium release experiment, two DMSP satellite overflights, all-sky photography, and incoherent scatter radar measurements provided information on the large-scale plasma convection over the polar cap region while a second rocket instrumented with a DC magnetometer, Langmuir and electric field probes, and an electron spectrometer provided measurements of small-scale electrodynamics. The large-scale data indicate that small, sun-aligned precipitation events formed within a region of antisunward convection between the duskside auroral oval and a large sun-aligned arc further poleward. This convection signature, used to assess the relationship of the sun-aligned arc to the large-scale magnetospheric configuration, is found to be consistent with either a model in which the arc formed on open field lines on the dusk side of a bifurcated polar cap or on closed field lines threading an expanded low-latitude boundary layer, but not a model in which the polar cap arc field lines map to an expanded plasma sheet. The antisunward convection signature may also be explained by a model in which the polar cap arc formed on long field lines recently reconnected through a highly skewed plasma sheet. The small-scale measurements indicate the rocket passed through three narrow (less than 20 km) regions of low-energy (less than 100 eV) electron precipitation in which the electric and magnetic field perturbations were well correlated. These precipitation events are shown to be associated with regions of downward Poynting flux and small-scale upward and downward field-aligned currents of 1-2 micro-A/sq m. The paired field-aligned currents are associated with velocity shears (higher and lower speed streams) embedded in the region of antisunward flow.
    Keywords: SPACE RADIATION
    Type: Alaska Univ., Theory, Image Simulation, and Data Analysis of Chemical Release Experiments; 12 p
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  • 24
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    Cosmic rays: Physics and astrophysics. A research briefing (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Some recent results in cosmic-ray physics are summarized, and how they raise new questions of interest for both physics and astrophysics is described. An important technical advance, the recently demonstrated capability of long-duration balloon flights of heavy payloads, will offer a great advantage for achieving some of these goals.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196118 , NAS 1.26:196118
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  • 25
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    Stochastic solution to quantum dynamics (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The quantum Liouville equation in the Wigner representation is solved numerically by using Monte Carlo methods. For incremental time steps, the propagation is implemented as a classical evolution in phase space modified by a quantum correction. The correction, which is a momentum jump function, is simulated in the quasi-classical approximation via a stochastic process. The technique, which is developed and validated in two- and three- dimensional momentum space, extends an earlier one-dimensional work. Also, by developing a new algorithm, the application to bound state motion in an anharmonic quartic potential shows better agreement with exact solutions in two-dimensional phase space.
    Keywords: SPACE RADIATION
    Type: NASA-TP-3408 , L-17295 , NAS 1.60:3408
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  • 26
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    Recent space shuttle observations of the South Atlantic anomaly and the radiation belt models (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-04-02
    Description: Active ingredients consisting of Tissue Equivalent Proportional Counter (TEPC) and a Proton and Heavy Ion Detector (PHIDE) have been carried on a number of Space Shuttle flights. These instruments have allowed us to map out parts of the South Atlantic Particle Anomaly (SAA) and to compare some of it's features with predictions of the AP-8 energetic proton flux models. We have observed that consistent with the generally observed westward drift of the surface features of the terrestial magnetic field of the SAA has moved west by about 6.9 degrees longitude between the epoch year 1970 of the AP-8 solar maximum model and the Space Shuttle observations made twenty years later. However, calculations indicate that except for relatively brief periods following very large magnetic storms the SAA seems to occupy the same position in L-space as in 1970. After the great storm of 24 March 1991 reconfiguration of the inner radiation belt and/or proton injection into the inner belt, a second energetic proton belt was observed to form at approximately equal to 2. As confirmed by a subsequent flight observations, this belt was shown to persist at least for six months. Our measurements also indicate an upward shift in the L location of the primary belt from L = 1.4 to L = 1.5. In addition we confirm through direct real time observations the existence and the approximate magnitude of the East-West effect. If the need exists for improved and updated radiation belt models in the Space Station era, these observations point out the specific features that should be considered and incorporated when this task is undertaken.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 911-921
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  • 27
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    Analysis of radiation risk from alpha particle component of soalr particle events (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-04-02
    Description: The Solar Particle Events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and Linear Energy Transfer (LET) spectra in shielding are discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 661-670
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  • 28
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    Search for gamma-ray events in the BATSE data base (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We find large location errors and error radii in the locations of channel 1 Cygnus X-1 events. These errors and their associated uncertainties are a result of low signal-to-noise ratios (a few sigma) in the two brightest detectors for each event. The untriggered events suffer from similarly low signal-to-noise ratios, and their location errors are expected to be at least as large as those found for Cygnus X-1 with a given signal-to-noise ratio. The statistical error radii are consistent with those found for Cygnus X-1 and with the published estimates. We therefore expect approximately 20 - 30 deg location errors for the untriggered events. Hence, many of the untriggered events occurring within a few months of the triggered activity from SGR 1900 plus 14 are indeed consistent with the SGR source location, although Cygnus X-1 is also a good candidate.
    Keywords: SPACE RADIATION
    Type: NASA-CR-197044 , NAS 1.26:197044
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  • 29
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    Performance study of galactic cosmic ray shield materials (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The space program is faced with two difficult radiation protection issues for future long-term operations. First, retrofit of shield material or conservatism in shield design is prohibitively expensive and often impossible. Second, shielding from the cosmic heavy ions is faced with limited knowledge on the physical properties and biological responses of these radiations. The current status of space shielding technology and its impact on radiation health is discussed herein in terms of conventional protection practice and a test biological response model. The impact of biological response on the selection of optimum materials for cosmic ray shielding is presented in terms of the transmission characteristics of the shield material. Although the systematics of nuclear cross sections are able to demonstrate the relation of exposure risk to shield-material composition, the current uncertainty in-nuclear cross sections will not allow an accurate evaluation of risk reduction. This paper presents a theoretical study of risk-related factors and a pilot experiment to study the effectiveness of choice of shield materials to reduce the risk in space operations.
    Keywords: SPACE RADIATION
    Type: NASA-TP-3473 , L-17389 , NAS 1.60:3473
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  • 30
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    Gamma-ray burst constraints on the galactic frequency of extra-solar Oort clouds (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: With the strong CGRO/BATSE evidence that most gamma-ray bursts do not come from galactic neutron stars, models involving the accretion of a comet onto a neutron star (NS) no longer appear to be strong contenders for explaining the majority of bursts. If this is the case, then it is worth asking whether the lack of an observed galactic gamma-ray burst population provides a useful constraint on the number of comets and comet clouds in the galaxy. Owing to the previously unrecognized structural weakness of cometary nuclei, we find the capture cross sections for comet-NS events to be much higher than previously published estimates, with tidal breakup at distances R(sub b) approximately equals to 4 x 10(exp 10) cm from the NS. As a result, impacts of comets onto field NS's penetrating the Oort Clouds of other stars are found to dominate all other galactic NS-comet capture rates by a factor of 100. This in turn predicts that if comet clouds are common, there should be a significant population of repeater sources with (1) a galactic distribution, (2) space-correlated repetition, and (3) a wide range of peak luminosities and luminosity time histories. If all main sequences stars have Oort Clouds like our own, we predict approximately 4000 such repeater sources in the Milky Way at any time, each repeating on timescales of months to years. Based on estimates of the sensitivity of the CGRO/BATSE instrument and assuming isotropic gamma-ray beaming from such events, we estimate that a population of approximately 20-200 of these galactic NS-Oort Cloud gamma-ray repeater sources should be detectable by CGRO. In addition, if giant planet formation is common in the galaxy, we estimate that the accretion of isolated comets injected to the interstellar medium by giant planet formation should produce an additional source of galactic, nonrepeating events. Comparing these estimates to the three to four soft gamma-ray repeater sources detected by BATSE, one is forced to conclude that (1) comet impacts on NS's are inefficient at producing gamma-rays; or (2) the gamma-rays from such events are highly beamed; or (3) the fraction of stars in the galaxy with Oort Cloud like our own is not higher than a few percent.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196197 , NAS 1.26:196197
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  • 31
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    Preliminary estimates of nucleon fluxes in a water target exposed to solar-flare protons: BRYNTRN versus Monte Carlo code (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A baryon transport code (BRYNTRN) has previously been verified using available Monte Carlo results for a solar-flare spectrum as the reference. Excellent results were obtained, but the comparisons were limited to the available data on dose and dose equivalent for moderate penetration studies that involve minor contributions from secondary neutrons. To further verify the code, the secondary energy spectra of protons and neutrons are calculated using BRYNTRN and LAHET (Los Alamos High-Energy Transport code, which is a Monte Carlo code). These calculations are compared for three locations within a water slab exposed to the February 1956 solar-proton spectrum. Reasonable agreement was obtained when various considerations related to the calculational techniques and their limitations were taken into account. Although the Monte Carlo results are preliminary, it appears that the neutron albedo, which is not currently treated in BRYNTRN, might be a cause for the large discrepancy seen at small penetration depths. It also appears that the nonelastic neutron production cross sections in BRYNTRN may underestimate the number of neutrons produced in proton collisions with energies below 200 MeV. The notion that the poor energy resolution in BRYNTRN may cause a large truncation error in neutron elastic scattering requires further study.
    Keywords: SPACE RADIATION
    Type: NASA-TM-4565 , L-17378 , NAS 1.15:4565
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  • 32
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    X-ray remote sensing and in-situ spectroscopy for planetary exploration missions and gamma-ray remote sensing and in-situ spectroscopy for planetary exploration missions (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Detectors that will be used for planetary missions must have their responses calibrated in a reproducible manner. A calibration facility is being constructed at Schlumberger-Doll Research for gamma and x ray detectors. With this facility the detector response can be determined in an invariant and reproducible fashion. Initial use of the facility is expected for the MARS94 detectors. Work is continuing to better understand the rare earth oxyorthosilicates and to define their characteristics. This will allow a better use of these scintillators for planetary missions. In a survey of scintillating materials two scintillators were identified as promising candidates besides GSO, LSO, and YSO. These are CdWO4 and CsI(Tl). It will be investigated if a detector with a better overall performance can be assembled with various photon converters. Considerable progress was achieved in photomultiplier design. The length of an 1 inch diameter PMT could be reduced from 4.2 to 2.5 inches without performance degradation. This technology is being employed in the gamma ray detector for the NEAR project. A further weight and size reduction of the detector package can be achieved with miniaturized integrated power supplies.
    Keywords: SPACE RADIATION
    Type: NASA-CR-189352 , NAS 1.26:189352
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  • 33
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    Extension of the BRYNTRN code to monoenergetic light ion beams (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A monoenergetic version of the BRYNTRN transport code is extended to beam transport of light ions (H-2, H-3, He-3, and He-4) in shielding materials (thick targets). The redistribution of energy in nuclear reactions is included in transport solutions that use nuclear fragmentation models. We also consider an equilibrium target-fragment spectrum for nuclei with mass number greater than four to include target fragmentation effects in the linear energy transfer (LET) spectrum. Illustrative results for water and aluminum shielding, including energy and LET spectra, are discussed for high-energy beams of H-2 and He-4.
    Keywords: SPACE RADIATION
    Type: NASA-TP-3472 , L-17394 , NAS 1.60:3472
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  • 34
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    Search for inverse Compton x-rays from the lobes of Fornax A x-rays from radio galaxies straddling the Fanaroff-Riley transition (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two related studies of radio galaxies are covered in this report. The first is a search for inverse Compton x-rays from the lobes of Fornax A. In this study, a ROSAT position sensitive proportional counter image of Fornax A (NGC 1316) is presented, and after image processing, it was observed that the x-ray emission closely mimicked the radio emission. A second study involved x-rays from radio galaxies straddling the Fanaroff-Riley transition which divides radio galaxies into two broad morphological groups based on whether the lobe radio power is greater or less than a critical value. ROSAT HRI observations were obtained from four bright radio galaxies around the transition to search for x-ray indications of either nuclear engine or ambient medium differences.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196433 , NAS 1.26:196433
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  • 35
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    Relativistic shock spectra: A prediction (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: I argue that particles heated by relativistic shocks should assume an equilibrium energy distribution. This leads to a synchrotron spectrum F(sub nu) varies as nu(sup 1/3) up to approximately the critical frequency nu(sub 0) of an electron with the mean electron energy. Application to gamma ray bursts (GRB's) implies that a burst with 10(exp -5) erg/(sq cm s) of soft gamma-rays and h(nu(sub 0)) = 300 KeV should be about 18th magnitude in visible light and a few micro-Jy at 1 GHz (less if self-absorbed).
    Keywords: SPACE RADIATION
    Type: NASA-CR-194764 , NAS 1.26:194764
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  • 36
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    Radio and optical emission: Spectral shapes and breaks in GRB (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Relativistic blast wave models of Gamma Ray Bursts (GRB) predict the spectrum of the emitted synchrotron radiation. The electrons in the shocked region are heated to a Wien distribution whose 'temperature' is 1/3 of the mean electron energy. This energy determines a characteristic (break) frequency of synchrotron radiation. At much lower frequencies, a spectrum F(sub nu) varies as nu(sup 1/3) is predicted independently of the details of the emitting region. This is consistent with the observed soft x ray emission of GRB. It implies low visible and radio intensities, unless there are collective emission processes.
    Keywords: SPACE RADIATION
    Type: NASA-CR-194763 , NAS 1.26:194763
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  • 37
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    A search for pre- and post-burst emission from well-localized gamma-ray burst locations (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: We present the results from the first long-term search for nonburst gamma-ray emission from the positions of 70 intense, well-localized bursts. Using the BATSE occultation technique, designed for monitoring of discrete sources, these burst positions were measured in the energy range of approximately 15 keV to 1.8 MeV over a 112 day interval during 1991. None of these 70 locations exhibited detectable emission at or above the level of approximately 5 x 10(exp -9) ergs cm(exp -2) s(exp -1) during the 112 day interval. This level is approximately 1000 times less than the typical intensity of the burst associated with the given location. In addition, 35 intense gamma-ray bursts detected by BATSE were examined in a five day interval centered on the time of detection. We find no compelling evidence that these bursts emit preburst emission or display prompt postburst emission at a level of approximately 5 x 10(exp -9) ergs cm(exp 2) s(exp -1) on timescales of approximately 1 hr or longer. The lack of detectable long-term emission or preburst and postburst emission from the positions of gamma-ray bursts has important consequences for a variety of burst production models.
    Keywords: SPACE RADIATION
    Type: NASA-CR-195825 , NAS 1.26:195825
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  • 38
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    Secondary ionization in a flat universe (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: We analyze the effect of a secondary ionization on the evolution of temperature fluctuations in cosmic background radiation. The main results presented in this paper are appropriate analytic expressions of the transfer function relating temperature fluctuations to matter density perturbations at recombination for all possible recombination histories. Furthermore, we particularize our calculation to the standard cold dark matter model, where we study the erasure of primordial temperature fluctuations and calculate the magnitude and angular scale of the damping induced by a late recombination.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 420; 1; p. 26-32
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  • 39
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    Weak soft X-ray excesses need not result from the high-frequency tail of the optical/ultraviolet bump in active galactic nuclei (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The broad-band ROSAT/EXOSAT X-ray spectra of six Seyfert 1 galaxies are fitted by a model consisting of a direct power law and a component due to reflection/reprocessing from a partially ionized, optically thick medium. The reflected spectrum contains emission features from various elements in the soft X-ray range. In all objects but one (Mrk 335), the fit is satisfactory, and no additional soft X-ray excess is required by the data. This means that in most sources there is no need for the thermal 'big blue bumps' to extend into soft X-rays, and the soft X-ray excesses reported previously can be explained by reflection/reprocessing. Satisfactory fits are obtained for a medium ionized by a source radiating at less than or approximately 15% of the Eddington rate. The fits require that the reflection is enhanced relative to an isotropically emitting source above a flat disk. The necessary high effectiveness of reflection in the soft X-ray band requires strong soft thermal flux dominating over hard X-rays.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 431; 1; p. L5-L8
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  • 40
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    Simultaneous optical/gamma-ray observations of GRBs (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Details on the project to search for serendipitous time correlated optical photographic observations of Gamma Ray Bursters (GRB's) are presented. The ongoing photographic observations at nine observatories are used to look for plates which were exposed simultaneously with a gamma ray burst detected by the gamma ray instrument team (BATSE) and contain the burst position. The results for the first two years of the gamma ray instrument team operation are presented.
    Keywords: SPACE RADIATION
    Type: Max-Planck Inst. fuer Extraterrestrische Physik, Reports on Simultaneous Optical(Gamma-Ray Observations of Gamma Ray Bursts; 5 p|Huntsville Gamma-Ray Burst Workshop; Oct 01, 1993; Huntsville, AL; United States
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  • 41
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    Theory, Image Simulation, and Data Analysis of Chemical Release Experiments (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The final phase of Grant NAG6-1 involved analysis of physics of chemical releases in the upper atmosphere and analysis of data obtained on previous NASA sponsored chemical release rocket experiments. Several lines of investigation of past chemical release experiments and computer simulations have been proceeding in parallel. This report summarizes the work performed and the resulting publications. The following topics are addressed: analysis of the 1987 Greenland rocket experiments; calculation of emission rates for barium, strontium, and calcium; the CRIT 1 and 2 experiments (Collisional Ionization Cross Section experiments); image calibration using background stars; rapid ray motions in ionospheric plasma clouds; and the NOONCUSP rocket experiments.
    Keywords: SPACE RADIATION
    Type: NASA-CR-194865 , NAS 1.26:194865
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  • 42
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    Network synthesis localization of two soft gamma repeaters (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: We introduce the method of 'network synthesis,' which allows the detection of very weak gamma-ray transient signals in the data of the Ulysses gamma-ray burst (GRB) experiment from repeating sources. It consists of defining a grid of alpha, delta values, and for each BATSE detection of a burst from a soft gamma repeater, predicting the arrival time of the burst at Ulysses and co-adding the Ulysses data rephased so that the burst signals are aligned in time and produce a detectable pulse. We demonstrate that this method identifies the position of the soft repeater SGR 1806-20, and apply it to the repeater B1900+14. We show that the counterpart to this burst source is probably in or in the vicinity of the Galactic supernova remnant G42.8+0.6.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 431; 1; p. L31-L34
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  • 43
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    An instrument to measure the charge, and energy spectrum (20-1000 GeV/a) of the cosmic ray species oxygen to iron (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: BUGS-4 (Bristol University Gas Scintillator-4) made its maiden engineering flight from Fort Summer (NM) on the 29th of September 1993. The instrument was consumed by fire after striking a power line during landing following 24 hours at float. The analysis of the telemetered data from this sophisticated instrument is a demanding task. Early analysis was compromised by electronic artifacts. Unravelling these problems has been difficult and time consuming, especially as the flight hardware was burned beyond salvage, but is is an essential preliminary to analysis. During this report period we have concentrated on a small sub-set of data (the first 30,000 events; 90 minutes at float), and developed software algorithms to correct systematic errors. Using these corrected events we have begun to develop the analysis algorithms. Although the analysis is preliminary, and restricted to the first 30,000 events, the results are encouraging, and suggest the design concepts are well matched to this application. Further work will refine the analysis, and allow quantitative evaluation of the concepts employed in BUGS-4 for applicability to future instruments. We believe this work will justify fabrication of a new instrument employing techniques deployed on BUGS-4.
    Keywords: SPACE RADIATION
    Type: NASA-CR-197555 , NAS 1.26:197555
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  • 44
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    Plasma and radio waves from Neptune: Source mechamisms and propagation (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this project was to conduct a comprehensive investigation of the radio wave emission observed by the planetary radio astronomy (PRA) instrument on board Voyager 2 as it flew by Neptune. The study has included data analysis, theoretical and numerical calculations, and ray tracing to determine the possible source mechanisms and locations of the radiation, including the narrowband bursty and smooth components of the Neptune radio emission.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196284 , NAS 1.26:196284
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  • 45
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    BATSE Data Analysis (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The four primary tasks of the Burst and Transient Source Experiment (BATSE) were completed. The Detector Response Matrices were maintained and some improvements implemented. The spectral analysis tasks based on the 4 channel lad data were accomplished. The BLOT team effort was completed and the SN1987A balloon flight data analysis paper was submitted.
    Keywords: SPACE RADIATION
    Type: NASA-CR-193930 , NAS 1.26:193930
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  • 46
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    An iron absorption model of gamma-ray burst spectra (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of sight the absorbed spectrum can indeed mimic the typial GRB spectrum. This model predicts that (a) the spectrum should evolve monotonically from hard to soft during each energy release, which is observed in most bursts, especially in fast rise exponential decay bursts; (b) Fe spectral features near 7 keV may be present in some bursts; and (c) the ratio of burst distances to the CBM and to Earth should be approximately 10(exp -11) if the spectral evolution is purely due to Fe stripping by the photons.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 432; 2; p. L111-L114
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  • 47
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    The first Extreme Ultraviolet Explorer source catalog (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Extreme Ultraviolet Explorer (EUVE) has conducted an all-sky survey to locate and identify point sources of emission in four extreme ultraviolet wavelength bands centered at approximately 100, 200, 400, and 600 A. A companion deep survey of a strip along half the ecliptic plane was simultaneously conducted. In this catalog we report the sources found in these surveys using rigorously defined criteria uniformly applied to the data set. These are the first surveys to be made in the three longer wavelength bands, and a substantial number of sources were detected in these bands. We present a number of statistical diagnostics of the surveys, including their source counts, their sensitivites, and their positional error distributions. We provide a separate list of those sources reported in the EUVE Bright Source List which did not meet our criteria for inclusion in our primary list. We also provide improved count rate and position estimates for a majority of these sources based on the improved methodology used in this paper. In total, this catalog lists a total of 410 point sources, of which 372 have plausible optical ultraviolet, or X-ray identifications, which are also listed.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal: Supplement Series (ISSN 0067-0049); 93; 2; p. 569-587
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    X-ray emission from the edge-on spiral galaxy NGC 4631 (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: This grant supported research of the X-ray emission from the disk and halo of the edge-on spiral galaxy NGC 4631, using data from the ROSAT satellite. The data were obtained on the basis of a proposal submitted by the PI, which was highly ranked in the peer review. It is a pleasure to say that the goals of the project, imaging and spectroscopy of hot gas in the disk and halo of a vigorously star forming galaxy, have been achieved. The results of the project have been submitted for publication, and are in press. A list of the publications is included.
    Keywords: SPACE RADIATION
    Type: NASA-CR-197536 , NAS 1.26:197436
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    Gamma ray emission from radio pulsars (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: While the proposed research received partial funding under this grant, during the term of support substantial progress was made on the development of a new model for the emission of gamma-rays from isolated rotation-powered pulsars. In phase one of the work, we showed how a modified version of the 'outer gap' model of pulsar emission could reproduce the double peaked profiles seen in CGRO pulsar observations. This work also demonstrated the spectrum of gap radiation varies significantly with position in the magnetosphere, and produced approximate computations of the emission from outer magnetosphere gap zones, including primary curvature radiation, gamma - gamma pair production and synchrotron radiation and inverse Compton scattering by the resulting secondary particles. This work was followed in phase two by a more complete treatment of the geometry of the radiation zone, and improved connections with observations at other wavelengths.
    Keywords: SPACE RADIATION
    Type: NASA-CR-197917 , NAS 1.26:197917
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  • 50
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    Galactic cosmic ray composition and energy spectra (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Galactic cosmic ray nuclei represent a significant risk to long-duration spaceflight outside the magnetosphere. We review briefly existing measurements of the composition and energy spectra of heavy cosmic ray nuclei, pointing out which species and energy ranges are most critical to assessing cosmic ray risks for spaceflight. Key data sets are identified and a table of cosmic ray abundances is presented for elements from H to Ni (Z = 1 to 28). Because of the 22-year nature of the solar modulation cycle, data from the approaching 1998 solar minimum is especially important to reducing uncertainties in the cosmic ray radiation hazard. It is recommended that efforts to model this hazard take advantage of approaches that have been developed to model the astrophysical aspects of cosmic rays.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 737-747
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    Scientific and technical support for the Galileo net flux radiometer experiment (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This report describes work supported by a post-launch grant (NCC 2-679) that originally covered the period from 1 January 1990 through 31 December 1992. This was extended an additional nine months at no cost until 30 September 1993, and once more until to 30 November 93. A final report on the effort from 1 January 1990 through 30 November 1993 (anticipated) is provided following the background discussion. Tasks required during the post launch period are briefly as follows: (1) attend PSG (Project Science Group) meetings; (2) support in-flight checkouts; maintain and keep safe the spare instrument and GSE (Ground Support Equipment); (3) organize and maintain documentation; (4) finish calibration measurements, documentation, and analysis; (5) characterize and diagnose instrument anomalies; (6) develop descent data analysis tools; and (7) science data analysis and publication. The following sections provide background information on the NFR instrument followed by the complete progress report.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196009 , NAS 1.26:196009
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  • 52
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    Compton Gamma Ray Observatory/BATSE observations of energetic electrons scattered by cyclotron resonance with waves from powerful VLF transmitters (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: To obtain a better understanding of the wave-particle mechanisms responsible for the loss of electrons from the radiation belts, energetic electron data from the Burst and Transient Source Experiment (BATSE) on the NASA's Compton Gamma Ray Observatory (GRO) was studied. Powerful ground-based VLF transmitters resonantly scatter electrons from the inner radiation belt onto trajectories from which they precipitate into the atmosphere as they drift eastward. 563 instances in which the satellite traversed a cloud of energetic electrons which had been scattered into quasi-trapped trajectories were identified. From the longitude distribution, it was concluded that waves from the VLF transmitter NWC at 114 deg E are the origin of 257 of the events, and waves from UMSat 44 deg E related to 45 more. In another 177 cases the electrons had drifted from the longitude of these transmitters to a location in the western hemisphere. The previously reported seasonal variation in the frequency of occurrence of cyclotron resonance interaction is confirmed with the continuous coverage provided by GRO. The frequency of occurrence of the cyclotron resonance interactions is largest before sunrise, which we attribute to the diurnal variations in the transmission VLF waves through the ionosphere. For the first time, unique very narrow sheets of electrons occurring in the aftermath of a large geomagnetic storm are reported.
    Keywords: SPACE RADIATION
    Type: NASA-CR-189336 , NAS 1.26:189336 , LMSC-F254276
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    MACHOs and the diffuse X-ray background (1994)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: The possible contribution of X-ray emission from massive compact objects in the Galactic halo (MACHOs) to the diffuse X-ray background is explored. We show that such emission cannot be responsible for the shadowing seen in soft X-ray observations by ROSAT but that these objects may indeed contribute significantly (at levels greater than 10%) to the diffuse background at higher (greater than or approximately 0.5 keV) energies. Thus, X-ray observations may well be able to significantly constrain the spatial distribution of MACHOs.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal (ISSN 0004-637X); 431; 2 pt; p. L87-L90
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  • 54
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    On the energetics and number of gamma-ray pulsars (1994)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: We examine a nearly aligned pulsar model with polar cap acceleration in order to explain the energetics and number of the known gamma-ray pulsars. In this model, the efficiency of converting spin-down luminosity to gamma-ray luminosity increases with decreasing spin-down luminosity, a trend recently emphasized by Ulmer. The predicted gamma-ray flux is proportional to dot P(exp 3/4)/P(exp 5/4) d(exp 2), where P is the period, dot P is the period derivative, and d is the distance to the pulsar. For initial spin periods between approximately equals 10 and 30 ms and neutron star polar magnetic fields between approximately equals 1 and 4 TG, this model accounts for the number and age distribution of the five pulsars which have been observed to emit gamma rays at energies greater than 100 MeV. Implications for pulsar studies are considered.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 420; 2; p. L75-L78
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  • 55
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    Duration versus brightness of gamma-ray bursts: Comparisons between SIGNE and BATSE (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: We analyze duration and brightness distributions of both the SIGNE Venera 13 and 14 and Burst and Transient Source Experiment (BATSE) gamma-ray burst databases. Choosing T(sub 50) as a measure of the burst duration and using both 64 and 1024 ms peak count rates, we search for correlations between duration, peak brightness, and the ratio V identically equals C(sub 64)/C(sub 1024), proposed as a measure of variability by Lamb, Graziani, & Smith. The duration histogram for SIGNE shows a long-duration peak that is consistent with BATSE, but does not exhibit the short population, instead appearing flat below 0.6 s; the difference is presumably caused by the failure of SIGNE to detect the short, faint bursts that were observed by BATSE. Estimating the instantaneous brightness by C(sub 64), we find that SIGNE confirms the BATSE result that the long and short bursts have similar maximum instantaneous brightnesses. Scatterplots between duration, brightness, and V are consistent for both databases; we show that SIGNE confirms the BATSE observation that there is a lack of bursts that are both bright over 1024 ms and contain a short, bright spike.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 421; 2; p. L83-L86
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  • 56
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    Hard X-rays from SN 1993J (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Observatory observed SN 1993J during three intervals centered approximately 12, 30, and 108 days after its outburst. Hard X-ray emission was detected in the first two of these intervals. No emission was seen in the third observation or in two earlier observations in 1991 and 1992. The coincidence of the observed excess with the outburst of SN 1993J and the consistency of the spectra and time evolution with those seen at lower energies by ROSAT and ASCA (Astro-D) argue that the observed emission is indeed from SN 1993J. It is probably due to the interaction of the fast supernova ejecta with circumstellar material. The luminosity, 5 x 10(exp 40) ergs/sec (50-150 keV) in the first interval, is significantly larger than predicted. Extrapolating the spectrum to a few keV accounts for most or all of the observed emission at low energy. The observed high temperature, 10(exp 9) K, is easily obtained in the shocked circumstellar matter, but a surprisingly high density is required there to give the observed luminosity, and little or no additional X-ray emission from denser shocked supernova ejecta is allowed. The hard emission might also be explained in terms of the shocked supernova ejecta itself with unexpectedly high temperature.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal (ISSN 0004-637X); 431; 2, pt; p. L95-L98
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  • 57
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    Observations of enhanced sub-iron (Sc-Cr) to Iron abundance ratios in the low energy galactic cosmic rays in Spacelab-3 and their implications (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The Anuradha cosmic ray experiment in Spacelab-3, flown in the orbit at 350 km with an inclination of 57 deg for about six days, was used to measure the low energy galactic cosmic ray (GCR) heavy ions using a specially designed CR-39 detector module incorporating the arrival time information of the particles. The abundances of sub-iron (Sc-Cr) and iron particles in the low energy interval of 30-300 MeV/N were determined from the measurements made in four different depths of the Cr-39 detector module of 150 layers. From these studies we obtained sub-iron (Sc-Cr) to iron abundance ratios of 0.8 to 1.2 in 30-300 MeV/N energy range. It is found that these ratios are enhanced by a factor of two as compared to interplanetary ratios of about 0.5. It is shown that the enhancement of the ratio inside the earth's magnetosphere is probably due to the degree of ionization of low energy Sc to Cr and Fe ions in the galactic cosmic rays and to the rigidity filtering effects of the geomagnetic field. Further studies are needed to understand fully the phenomena and their implications.
    Keywords: SPACE RADIATION
    Type: Journal of Astrophysics and Astronomy (ISSN 0250-6335); 15; 1; p. 85-94
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    Low-frequency spectra of gamma-ray bursts (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Particles with energies below the mean energy E(sub 0) in relativistic shocked plasmas should assume an equilibrium energy distribution. This leads to a synchrotron spectrum F(sub nu) proportional to nu(exp 1/3) up to approximately the critical frequency nu(sub 0) of an electron with the energy E(sub 0). Application to gamma-ray bursts (GRBs) implies that a burst with 10(exp -5) ergs/sq cm/s of soft gamma rays and h nu(sub 0) = 300 keV should simultaneously be about 18th magnitude in visible light and a few micro-J at 1 GHz (less if self-absorbed); the low-freqency intensities peak later at higher values.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 432; 2; p. L107-L109
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    A model of galactic cosmic rays for use in calculating linear energy transfer spectra (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The Galactic Cosmic Rays (GCR) contain fully stripped nuclei, from Hydrogen to beyond the Iron group, accelerated to high energies and are a major component of the background radiation encountered by satellites and interplanetary spacecraft. This paper presents a GCR model which is based upon our current understanding of the astrophysics of GCR transport through interstellar and interplanetary space. The model can be used to predict the energy spectra for all stable and long-lived radioactive species from H to Ni over an energy range from 50 to 50,000 MeV/nucleon as a function of a single parameter, the solar modulation level phi. The details of this model are summarized, phi is derived for the period 1974 to present, and results from this model during the 1990/1991 Combined Release and Radiation Effects Satellite (CRRES) mission are presented.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 765-769
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    A model of solar energtic particles for use in calculating LET spectra developed from ONR-604 data (1994)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: A model of Solar Energetic Particles (SEP) has been developed and is applied to solar flares during the 1990/1991 Combined Release and Radiation Effects Satellite (CRRES) mission using data measured by the University of Chicago instrument, ONR-604. The model includes the time-dependent behavior, heavy-ion content, energy spectrum and influence, and can accurately represent the observed SEP events in the energy range between 40 to 500 MeV/nucleon. Results are presented for the March and June, 1991 flare periods.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 675-680
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  • 61
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    Generation of radiation in solar corona and interplanetary space by energetic electrons (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Emissions of electromagnetic waves with frequencies close to the plasma frequency and/or its second harmonic have been frequently observed in the solar corona and interplanetary space. In the past, a number of theories have been put forward to esplain the generation mechanism of the observed radiation. In this paper, a new model is proposed. The essential point of the present theory is that the Langmuir waves amplified as a result of the usual beam instability can lead to two important effects: first, electrostatic waves with frequencies close to twice the plasma frequency can be excited; and second, a significant modification of the dispersion relation can occur, so that these electrostatic waves can naturally change into electomagnetic waves as they propagate in a plasma in which the plasma density decreases spatially. The latter effect is attributed to a mode couplng process. In addition to the second harmonic emission, emission at the fundamental is also briefly discussed. In this case, as in many other theories, the presence of a very low frequency electostatic wave such as the ion-acoustic wave is assumed. The emission process discussed in the present theory stresses the importance of mode coupling and conversion rather than kinetic processes such as a nonlinear wave-wave or wave-particle scattering.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 429; 1; p. 406-414
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  • 62
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    On the bimodal distribution of gamma-ray bursts (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Kouveliotou et al. recently confirmed that gamma-ray bursts are bimodal in duration. In this paper we compute the statistical properties of the short (less than or = 2 s) and long (greater than 2 s) bursts using a method of analysis that makes no assumption regarding the location of the bursts, whether in the Galaxy or at a cosmological distance. We find the 64 ms channel on Burst and Transient Source Experiment (BATSE) to be more sensitive to short bursts and the 1024 ms channel to be more sensitive to long bursts. We show that all the currently available data are consistent with the simple hypothesis that both short and long bursts have the same spatial distribution and that within each population the sources are standard candles. The rate of short bursts per unit volume is about 40% of the rate of long bursts. Although the durations of short and long gamma-ray bursts span several orders of magnitude and the total energy of a typical short burst is smaller than that of a typical long burst by a factor of about 20, surprisingly the peak luminosities of the two kinds of bursts are equal to within a factor of about 2.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 420; 1; p. 171-176
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  • 63
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    Unsteady outflow models for cosmological gamma-ray bursts (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The 'event' that triggers a gamma-ray burst cannot last for more than a few seconds. This is, however, long compared with the dynamical timescale of a compact stellar-mass object (approximately 10 (exp-3) s). Energy is assumed to be released as an outflow with high mean Lorentz factor Gamma. But a compact stellar-mass collapse or merger is, realistically, likely to generate a mass (or energy) flux that is unsteady on some timescales in the range 10(exp -3) - 10 s. If Gamma fluctuates by a factor of approximately 2 around its mean value, relative motions within the outflowing material will themselves (in the comoving frame) be relativistic, and can give rise to internal shocks. For Gamma approximately 10(exp 2), the resultant dissipation occurs outside the 'photosphere' and can convert a substantial fraction of the overall outflow energy into nonthermal radiation. This suggests a mechanism for cosmological bursts that demands less extreme assumptions (in respect of Gamma-values, freedom from baryonic contamination, etc.) than earlier proposals.
    Keywords: SPACE RADIATION
    Type: The Astrophysical Journal (ISSN 0004-637X); 430; 2 pt; p. L93-L96
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    Very High Energy Gamma Ray Extension of GRO Observations (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.
    Keywords: SPACE RADIATION
    Type: NASA-CR-197489 , NAS 1.26:197489
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  • 65
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    Non-dipolar magnetic field models and patterns of radio emission: Uranus and Neptune compared (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The magnetic field geometries of Uranus and Neptune are superficially similar, and are similarly unlike those of other planets: the field strengths are similar, and they contain extraordinarily large non-dipolar components. As a corollary, the best dipolar field models of each of the two planets comprises a dipole that is considerably offset from the planetary center and tilted away from the rotational axis. However, in other respects the best field models of the two planets are quite different. Uranus has a quadrupole model in which all the terms are well determined and in which none of the higher order terms is determined. To represent the magnetometer data acquired during Voyager's Neptune encounter requires a model of order 8 (instead of Uranus' order 2), yet many of the coefficients are poorly determined. A second model, an octupole model comprising the terms up to order three of the order 8 model, has been suggested by the magnetometer team as being useful; its use, however, is limited only to the region outside of about 2R(exp N), whereas planetary radio emissions have their sources well inside this surface. Computer code has been written that permits an analysis of the detailed motion of low energy charged particles moving in general planetary magnetic fields. At Uranus, this code reveals the existence of an isolated region of the inner magnetosphere above the day side in which particles may be trapped, separate from the more general magnetospheric trapping. An examination of the so-call ordinary mode uranian radio emissions leads us to believe that these emissions are in fact extraordinary mode emissions coming from particles trapped in this isolated region. A similar attempt to discover trapping regions at Neptune has proved, unfortunately, to be impossible. This arises from three factors: (1) the computation needed to track particles in an eighth order field is more than an order of magnitude greater than that needed to perform a similar calculation in a quadrupole field, and is beyond the capacity of workstation-class computers; (2) the octupole field model is known to be in error by too large an ammount for it, or any similarly truncated version of the eighth order model, to produce trustworthy results; (3) the eighth order model can, in effect, be infinitely varied without affecting the field strength along the spacecraft trajectory.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196412 , NAS 1.26:196412
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    GRO: Black hole models for gamma-ray bursts (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The possibility of creating gamma ray bursts (GRB's) from accretion flows on to black holes is investigated. The mechanism of initial energy release in the form of a burst is not understood yet. The typical time scales involved in this energy release and the initial distribution of photons as a function of energy are studied. As a first step the problem is formulated in the Minkowski spacetime for a homogeneous and isotropic burst. For an arbitrary initial distribution of photons, the equations of relativistic kinetic theory are formulated for nonequilibrium plasmas which can take into account various particle creation and annihilation processes and various scattering processes.
    Keywords: SPACE RADIATION
    Type: NASA-CR-196308 , NAS 1.26:196308 , CAL-2208
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    Galactic cosmic ray abundances and spectra behind defined shielding (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Linear Energy Transfer (LET) spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 deg to 83 deg inclination. In some of the experiments the flux of Galactic Cosmic Rays (GCR) was determined separately from contributions caused by interactions in the detector material. Results of these experiments are compared to model calculations. The general agreement justifies the use of the model to calculate GCR fluxes. The magnitude of variations caused by solar modulation, geomagnetic shielding, and shielding by matter determined from calculated LET spectra is generally in agreement with experimental data. However, more detailed investigations show that there are some weak points in modeling solar modulation and shielding by material. These points are discussed in more detail.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 815-824
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    Comparison of model predictions with LDEF satellite radiation measurements (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Some early results are summarized from a program under way to utilize Long Duration Exposure Facility (LDEF) satellite data for evaluating and improving current models of the space radiation environment in low Earth orbit. Reported here are predictions and comparisons with some of the LDEF dose and induced radioactivity data, which are used to check the accuracy of current models describing the magnitude and directionality of the trapped proton environment. Preliminary findings are that the environment models underestimate both dose and activation from trapped protons by a factor of about two, and the observed anisotropy is higher than predicted.
    Keywords: SPACE RADIATION
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 17-20
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    A measurement of the energy spectra of cosmic rays from 20 to 1000 GeV per AMU (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: During the report period the BUGS-4 instrument was completed, and the maiden voyage took place on 29 September from Fort Sumner, New Mexico. The successful flight of a large spherical drift chamber is a unique first for the sub-orbital balloon program. Unfortunately the instrument was consumed by fire after striking a power line during landing. However, while at float altitude, circa 24 hours of data were telemetered. The pre-flight preparations, and flight operations are described.
    Keywords: SPACE RADIATION
    Type: NASA-CR-195246 , NAS 1.26:195246
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    An analysis of gamma ray burst time histories (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Gamma ray burst time histories, ranging in durations from milliseconds to thousands of seconds, are as varied as the number of bursts. They show a wide array of structures from those that are very smooth to those that contain a seemingly uncountable number of spikes riding on top of other spikes. These profiles have tantalized researchers for years - they obviously hold important information on the nature of GRB's, but to date no one has been successful in analyzing them. For the past year the author has been working on algorithms to analyze these data. Two approaches have been followed in this investigation. The first is an attempt to quantify the amount of structure, or spikiness, in a profile. The second involves applying the latest theorems on chaos and fractals with the aim of extracting useful information from what seems to be a random collection of shot noise.
    Keywords: SPACE RADIATION
    Type: NASA-CR-195191 , NAS 1.26:195191 , UAH-5-30166 , Summer Faculty Fellowship Research Continuation Program; Feb 01, 1994 - Feb 28, 1994; Huntsville, AL; United States
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    New description of charged particle propagation in random magnetic fields (1994)
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    Publication Date: 2019-08-27
    Description: When charged particles spiral along a large constant magnetic field, their trajectories are scattered by random components that are superposed on the guiding field. In the simplest analysis of this situation, scattering causes the particles to diffuse parallel to the guiding field. At the next level of approximation, moving pulses that correspond to a coherent mode of propagation are present, but they are represented by delta-functions whose infinitely narrow width makes no sense physically and is inconsistent with the finite duration of coherent pulses observed in solar energetic particle events. To derive a more realistic description, the transport problem is formulated in terms of 4 x 4 matrices, which derive from a representation of the particle distribution function in terms of eigenfunctions of the scattering operator, and which lead to useful approximations that give explicit predictions of the detailed evolution not only of the coherent pulses, but also of the diffusive wake. More specifically, the new description embodies a simple convolution of a narrow Gaussian with the solutions above that involve delta-functions, but with a slightly reduced coherent velocity. The validity of these approximations, which can easily be calculated on a desktop computer, has been exhaustively confirmed by comparison with results of Monte Carlo simulations which kept track of 50 million particles and which were carried out on the Maspar computer at Goddard Space Flight Center.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 425; 1; p. 331-342
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    NASA TECHNICAL REPORTS
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    Regional and age variations in growing tendon (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 221 (1994), S. 309-320 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gastrocnemius tendons of 10 White Leghorn chickens at 6, 8, and 12 weeks of age were divided into proximal, middle, and distal portions to assess regional variability in composition and growth. Body weight increases ∼ 150% during the period examined, whereas the lateral gastrocnemius muscle and tendon increase ∼ 193% and 227%, respectively. No significant changes in cellularity (DNA concentration) or hydroxypyridinium (OHP) crosslinks occur with increasing age. Hydroxyproline (HYP) concentration increases by 12 weeks of age, as hexuronate, glucosamine, and galactosamine decrease. Composition shows some regional variation: the distal region of the tendon has a lower HYP concentration, and increased GAGs and OHP crosslinks compared to either the proximal or middle regions, which do not differ from each other. The mean collagen fibril diameter increases with age, but the oldest tendons also contain more small diameter fibrils (〈40 nm). There is a unimodal fibril distribution at all three ages, although this has broadened by 12 weeks. The data from this study suggest that rapid tendon growth occurs throughout the time period examined and that changes characteristic of mature tendon, such as increased OHP crosslink concentration, have not yet developed in hatchlings because of the large amount of new tissue being produced. Whereas all three regions of the tendon are similar in size, composition of the distal region differs from that of the proximal and middle regions, suggesting that this portion of the tendon should be avoided when sampling a tendon. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052210306
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    Microscopic anatomy of pycnogonida: I. Cuticle, epidermis, and muscle (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 33-48 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The integument of Pycnogonida (Arthropoda) consists of an epicuticle decorated with tubercles and a filamentous coat, an exocuticle with a small number of ill-defined layers, and an endocuticle whose numerous layers are composed of conspicuously cross-banded fibrils. This cuticular periodicity, attributable to cross-linked chitin, has been observed previously in uncalcified and untanned cuticle of many lower crustaceans, especially branchiopods and copepods, and in scattered examples of thin respiratory or excretory cuticles of other arthropods. It is uniformly present in all representatives of all nine pycnogonid families examined to date. Stomodeal, proctodeal, and arthrodial cuticles are devoid of the endocuticular periodicity. The cuticle is decorated with sensory filaments and setae, but is more noteworthy for a dense coverage by glands, up to 1,400/mm2. Myocuticular junctions have desmosomal fine structure previously found only in chelicerates. Muscle fine structure is that of slow fibers with long sarcomeres and a high actin to myosin filament ratio, except for cardiac muscle, which has short sarcomeres. Among the arthropods, only merostomates resemble the pycnogonids in the lack of fast somatic muscle fibers. Pycnogonids display a hybrid array of fine structural features that variously serve to relate them to some arthropod subphyla and distance them from others. © 1994 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
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    Erratum (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 111-111 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052220111
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    Development and growth of compound tooth plates in Callorhinchus milii (chondrichthyes, holocephali) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 73-89 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The chimaeroid holocephalian fishes are distinguished among extant chondrichthyans by the possession of three pairs of tooth plates, evergrowing and partially hypermineralized, that are not shed and replaced like the teeth of living elasmobranchs. Although derivation of the chimaeroid tooth plate from the fusion of members of a plesiomorphic chondrichthyan tooth family has been proposed, evidence for this hypothesis has been lacking. A new analysis of the development and structure of the tooth plates in Callorhinchus milii (Holocephali, Chimaeriformes) reveals the compound nature of the tooth plates in a chimaeroid fish. Each tooth plate consists of an oral and aboral territory that form independently in the embryo and maintain separate growth surfaces through life. The descending lamina on the aboral surface of the tooth plate demarcates the growth surface of the aboral territory. Comparison with the tooth plates of Chimaera monstrosa indicates that compound tooth plates may be a feature of all chimaeroids in which a descending lamina is present. The tooth plates in these fishes represent the fusion of two members of a reduced tooth family. The condition of the tooth plates in C. milii is plesiomorphic for chimaeroids and is of evolutionary significance in that it provides further evidence to support a lyodont dentition in chimaeroid fishes similar to that found in other chondrichthyans. © 1994 Wiley-Liss, Inc.
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    Morphological and functional body reconstruction in a teleost of the genus Oreochromis (Cichlidae) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 1-6 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The process of morphological and functional regeneration was followed on a tilapid fish, a cross of Oreochromis aureus × Oreochromis niloticus, by observations on movements and the use of X-rays. A four-year-old adult fish that lost its tail as post larva, including ten vertebrae, was able to reconstruct a novel and shorter central skeleton, including a specially modified urostyle. The enlarged and strengthened pterygiophores and their junctions with the dorsal and anal spine formed a fast-holding base for the fins, the posterior part of which largely performed the functions of the missing caudal fin. Although the fish was much shorter than usual, this male behaved and functioned normally. © 1994 Wiley-Liss, Inc.
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    Ultrastructure of the paraphysis in Bufo bufo larvae (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 7-13 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the ultrastructure and function of the paraphysis in Bufo bufo larvae was carried out. The structure is a tubular-ramified gland made up of numerous tubules with monolayered epithelial walls surrounded by connective tissue and sinusoids. The epithelial cells secrete glycoprotein to contribute to production of the cephalorachidian fluid. The role of the paraphysis in the transport of fluids and electrolytes from the blood to the cephalorachidian fluid in regulation of ionic and osmotic homeostasis is discussed. © 1994 Wiley-Liss, Inc.
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    Characteristics of the flagellar axoneme in Neuroptera, Coleoptera, and Strepsiptera (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 15-20 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spermatozoa from representatives of the five insect orders in superorder Neuropteroidea were examined by electron microscopy following a new fixation method that includes tannic acid in the primary fixative but has uranyl acetate rather than osmium tetroxide as the secondary fixative. The sperm axoneme was found to be similar in the four orders Megaloptera, Raphidioptera, Neuroptera, and Coleoptera, and is characterized above all by its so-called intertubular material being divided into two portions, one located outside, but in contact with the doublet, and the other projecting from the accessory tubule and having a beak-like shape. These features have not been seen in insects from other orders and may be a synapomorphy for these neuropteroid orders. The accessory tubules in these four orders have 16 protofilaments. The shape of the accessory bodies adjacent to the mitochondrial derivatives is nearly the same in insects from the more primitive neuropteroid orders and in Coleoptera. The sperm tail of the examined strepsipteran deviates in several respects from that of other neuropteroids: the particle row in the wall of accessory tubules is incomplete, an intertubular material is missing, and the mitochondria contain no crystal. © 1994 Wiley-Liss, Inc.
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    Spiral cleavage and cell position contribute to the specification of the dorsoventral axis in the embryo of the archaeogastropod Haliotis tuberculata (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 21-33 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the embryo of Haliotis tuberculata spiral cleavage induces size differences between the quadrants in the 4-cell embryo. These size differences, together with the formation of compact cell configurations, induce asymmetrical positions of equivalent cells in the 8- and 16-cell embryo. The asymmetries in size and position influence the final specification of the dorsoventral asymmetry in the 32-cell embryo, as well as formation of the mesentoblast. © 1994 Wiley-Liss, Inc.
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    Eversible abdominal vesicles and some observations of the male reproductive system of the spoon wing lacewing Palmipenna (Neuroptera: Nemopteridae) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 47-58 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy and histology of the abdominal eversible vesicles and the male reproductive tract of the spoonwing lacewing Palmipenna (Neuroptera: Nemopteridae) have been examined. The eversible vesicles open as a pair of large bulbous sacs between tergites five and six, each folding into halves during retraction. They consist of highly pleated cuticle, beneath which are typical gland cells, each having a circular or oval end apparatus surrounded by closely packed microvilli. These communicate to the surface via cuticularized channels. In spite of considerable behavioral observations, male Palmipenna were never noted with everted vesicles. Even during mating trials, where females were presented to males in the field, the vesicles were never everted during the attempted copulation that ensued. Our observations indicate that mate attraction is mediated by the release of a female pheromone. The function of the eversible vesicles and their associated gland cells remains unknown, and their structure appears to be unique to the Nemopteridae. The reproductive tract is similar to that of other Neuroptera, consisting of a pair of five-lobed testes, a medium-to-large pair of seminal vesicles, and three pairs of accessory glands. The major accessory glands are surrounded by circular and longitudinal muscle, and are lined by an epithelium, the cells of which presumably secrete the amorphous rods of material always present in this pair of glands. The sperm in the seminal vesicles are elongate, with a pointed head and a 9 + 9 + 2 configuration in the flagellum. A single spermatophore, similar in shape to that described for other Neuroptera, was found occluding the bursa copulatrix of a teneral female. © 1994 Wiley-Liss, Inc.
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    In vivo fluorescence imaging of the functional organization of trophotaenial placental cells of goodeid fishes (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 35-46 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of viviparous goodeid fishes undergo a 10 to 150 × increase in dry weight during gestation. Maternal nutrients are transferred across a trophotaenial placenta comprised of the ovarian lumenal epithelium and the trophotaeniae of the embryo. Trophotaeniae are externalized projections of the embryonic hindgut. Epithelial cells of the ribbon trophotaenia (Ameca splendens) resemble intestinal absorptive cells of suckling mammals and endocytose macromolecules. They possess an apical brush border, endocytotic complex, endosomal-lysosomal system, and apical and basal clusters of mitochondria. Cells of the rosette trophotaenia (Goodea atripinnis) lack an endocytotic apparatus, have small lysosomes, two mitochondrial clusters, and transport small molecules. Organelle-specific fluorescent probes were employed to characterize the functional organization of the two types of trophotaenial cells. In A. splendens, Lucifer Yellow, a membrane-impermeable tracer of vesicular transport, first appears in peripheral vesicles (15-45 sec), then passes into elongated tubular endosomes (1-3 min) and later appears in large central vacuoles (10-15 min). These vacuoles accumulate Acridine Orange, a classical probe for lysosomes, and have been shown to contain lysosomal enzymes. Endosomelysosome fusion was observed. In both A. splendens and G. atripinnis, Rhodamine 123 fluorescence was localized in two clusters of fine spots that corresponded to mitochondria. 4′,6-diaminido-2-phenyl-indole (DAPI) staining of nuclei established the positional relationships of cell organelles with respect to the nuclei. 3,3′-dihexyloxacarbo-cyanine iodide (DiOC6) revealed the perinuclear distribution of the endoplasmic reticulum. In order to compare in vivo fluorescence of Lucifer Yellow with previous ultrastructural observations, we employed fluorescence photoconversion and electron microscopy. © 1994 Wiley-Liss, Inc.
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    Ontogenesis and ultrastructure of seminal vesicles of the catfish, Clarias gariepinus (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 59-71 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogenesis and structural characteristics of the seminal vesicles in Clarias gariepinus (sharptooth catfish) were studied by light and electron microscopy and are described in detail. The seminal vesicles, beginning as simple protrusions from the vas efferentia, becomes more complex with age. Their distal ends become fingerlike and the bases form palm-like extensions. Juvenile male organs do not reveal any signs of seminal vesicles although spermatogenic tissue is already well delineated. The developing gonads contain clusters of large cells, close to the sperm duct and cysts of the testis, from which seminal vesicles are formed. Secretory epithelium lines the tubules of the seminal vesicles and becomes columnar as the tissue matures. Electron micro-graphs of these epithelial cells reveal two types of cells: opaque cells and cells with very vacuolized cytoplasm. Dense pinocytotic vesicles are present between the membranes of neighbouring seminal tubules and apical cell membranes facing the lumen. Maturation and onset of secretion by the secretory cells is accompanied by morphological changes. Protruding cylindrical cells become shortened, modified to cuboidal, rounded cells that send tubular extensions into the lumen. In the final stage of differentiation, only connective tissue membranes supporting the tubule walls remain intact. At the points of contact between the testis, seminal vesicles, and sperm duct, the epithelia of these organs often become confluent. The distal parts of the seminal vesicles, rarely contain sperm; during spawning sperm accumulated in the proximal tubules of the vesicles. © 1994 Wiley-Liss, Inc.
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994) 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/jmor.1052190201
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    External morphology and abundance of antennal sensilla in australian gryllacrididae (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 11-18 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The long (49-93 mm) antennae of two species of Australian gryllacridids have high total numbers of sensilla consisting of five sensillar types. Ametrus sp. 7 has 22,300 (♀) and 26,250 (♂) sensilla; although the antennae of males are 33% longer than those of females, their sensillar density was 11% less. Bothriogryllacris pinguipes has 26,700 (♂) and 31,900 (♀) sensilla; antennae of females are 55% longer than those of males but sensillar density is 23% less. Aporous sensilla chaetica form 94.5 to 99.5% of all sensilla; they are presumably mechanoreceptors. Uniporous trichoid contact chemoreceptors range from 75-900 in number. Olfactory, multiporous, basiconic sensilla range from 22-440 and olfactory, coeloconic sensilla from 16-235. Two to five multiporous lenticular organs occur on all but female A. sp. 7. Differences in sensillar abundance between males and females are discussed as well as are the relationships between sensillar diversity on gryllacridid mouthparts and antennae. © 1994 Wiley-Liss, Inc.
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    Immunofluorescent studies on titin and myosin in developing hearts of normal and cardiac mutant axolotls (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 19-32 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Homozygous recessive cardiac mutant gene c in the axolotl, Ambystoma mexicanum, results in a failure of the embryonic heart to initiate beating. Previous studies show that mutant axolotl hearts fail to form sarcomeric myofibrils even though hearts from their normal siblings exhibit organized myofibrils beginning at stage 34-35. In the present study, the proteins titin and myosin are studied using normal (+/+) axolotl embryonic hearts at stages 26-35. Additionally, titin is examined in normal (+/c) and cardiac mutant (c/c) embryonic axolotl hearts using immunofluorescent microscopy at stages 35-42. At tailbud stage-26, the ventromedially migrating sheets of precardiac mesoderm appear as two-cell-layers. Myosin shows periodic staining at the cell peripheries of the presumptive heart cells at this stage, whereas titin is not yet detectable by immunofluorescent microscopy. At preheartbeat stages 32-33, a myocardial tube begins to form around the endocardial tube. In some areas, periodic myosin staining is found to be separated from the titin staining; other areas in the heart at this stage show a co-localization of the two proteins. Both titin and myosin begin to incorporate into myofibrils at stage 35, when normal hearts initiate beating. Additionally, areas with amorphous staining for both proteins are observed at this stage. These observations indicate that titin and myosin accumulate independently at very early premyofibril stages; the two proteins then appear to associate closely just before assembly into myofibrils. Staining for titin in freshly frozen and paraffin-embedded tissues of normal embryonic hearts at stages 35, 39, and 41 reveals an increased organization of the protein into sarcomeres as development progresses. The mutant siblings, however, first show titin staining only limited to the peripheries of yolk platelets. Although substantial quantities of titin accumulate in mutant hearts at later stages of development (39 and 41), it does not become organized into myofibrils as in normal cells at these stages. © 1994 Wiley-Liss, Inc.
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994) 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Quantitative design of the skeleton in bird hatchlings: Does tissue compartmentalization limit posthatching growth rates? (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 113-131 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Based on a detailed description of hatchling skeletons of the precocial buttonquail (Turnix suscitator) and the altricial budgerigar (Melopsittacus undulatus), this report presents the hypothesis that the rate of avian posthatching growth is limited by the quantitative design (i.e., relative volumes of cartilage, bone, and marrow) of the hatchling skeletons. A Jarge portion of bone in the skeletal elements and fast growth are hypothesized to be mutually exclusive. This hypothesis is tested by morphometric techniques and by statistical comparison of morphometric and growth data. All predictions are met by the data, and the design of hatchling skeletons is described as determined by a tradeoff between tissue composition of skeletal elements and maximum rates of posthatching growth. The precocial design shows large bony areas that supposedly resist mechanical stress of locomotion; however, the relatively small cartilaginous areas exclude high growth rates. The altricial design shows the reverse relationship with small bony areas and a lack of locomotion on the one side but large cartilaginous areas and fast posthatching growth on the other side. © 1994 Wiley-Liss, Inc.
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    Kinematic analysis of jaw protrusion in orectolobiform sharks: A new mechanism for jaw protrusion in elasmobranchs (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 175-190 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Jaw protrusion is an important component of prey capture in fishes, although the mechanics of protrusion have thus far been studied largely in teleosts. Elasmobranchs are also able to protrude their jaws (Tricas and McCosker [1984] Proc. Cal. Acad. Sci. 43: 221-238; Tricas [1985] Mem. S. Calif. Acad. Sci. 8:81-91.; Frazzetta and Prange [1987] Copeia 4:979-993). Several related features of the feeding apparatus contribute to jaw protrusion in sharks. Labial cartilages form an extendible series attached dorsally to the anterolateral face of the palatoquadrate and ventrally to the anteroventral surface of Meckel's cartilage. The labial cartilage chain swings anterolaterally as the lower jaw is depressed, thrusting the labial margins forward to form a circular oral opening and displacing the jaw apparatus towards the food; this pattern is analogous to halecomorph and primitive actinopterygian fishes in which the maxilla swings forward (Lauder [1979] J. Zool. Lond. 187:543-578). The palatoquadrate and Meckel's cartilage also project anteriorly and represent the major contribution to protrusion. These movements occur simultaneously with enlargement of the oral cavity to generate suction. The wobbegong sharks (Orectolobidae) are specialized for jaw protrusion. The spotted wobbegong protrudes its jaw by 33% of its chondrocranial length using two different mechanical systems. In the first mechanism of jaw protrusion, the intermandibularis and interhyoideus muscles medially compress the lower jaw and hyomandibulae. Compression of the lower jaw results in a more acute symphyseal angle so that the anteroposterior alignment of the lower jaw increases due to the rotation of each lower jaw towards a saggital orientation. Distal compression of the hyomandibulae at their attachments to the jaws swings the jaws forward. The second mechanism involves rotation of the ceratohyal around a posterior process of the lower jaw, pushing the hyomandibulae anteroventrally, thereby pushing the jaw articulation ventrally and anteriorly to protrude the jaws. © 1994 Wiley-Liss, Inc.
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    Localization and distribution of gap junctions in normal and cardiomyopathic hamster heart (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 203-213 
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gap junctions in mammalian heart function to provide low-resistance channels between adjacent cells for passage of ions and small molecules. It is clear that the almost unrestricted passage of ions between cells, ionic coupling, is required for coordinate and synchronous contraction. This knowledge of gap junction function has made it important to study their properties in normal and abnormal tissues. In the present study, we analyzed gap junction distribution in normal and cardiomyopathic heart tissue utilizing immunofluorescent and electron microscopy techniques. Frozen, unfixed sections of age-matched normal and cardiomyopathic cardiac tissues were immunofiuorescently stained using an antibody directed against a specific peptide sequence of the connexin-43 gap junction protein. These studies revealed a characteristic punctate staining pattern for the intercalated discs in normal tissues. Some of the intercalated discs in cardiomyopathic hearts appeared to stain normally; however, others stained diffusely. The pixel intensity distribution of the confocal images demonstrated a marked difference of up to 90% increase in the number of pixels in cardiomyopathic myocardium (CM), yet the pixel intensity of gap junctions had a decrease of approximately 60%. This suggests the possibility that connexin-43 is present in CM cells in significant quantity; however, it does not become localized on the membranes as in normal cells. Electron-microscopic findings corroborate these observations on CM cells by showing an irregular distribution of intercalated discs relatively smaller in size with abnormal orientation and distribution. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220207
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994) 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052220301
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    Phylogenetic implications of structure of adult ovary and oogenesis in the penicillate diplopod, Eudigraphis nigricians (miyosi) (diplopoda: Myriapoda) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 223-230 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe some significant structures of the adult ovary in a Japanese penicillate diplopod, Eudigraphis nigricans, with respect to phylogenetic implications. The ovary is a long, saclike organ lying between the alimentary canal and the ventral nerve cord from the fourth through the ninth body segment. The ovarian wall consists of a thin ovarian epithelium and a sparse muscle covering. There are two types of oogenetic sites: a single, mound-shaped germarium sitting on the center of the ventral ovarian epithelium, and ∼ 10 pairs of patchlike vitellarial areas metamerically arranged anterior and posterior to the germarium. The germarium consists of oogonia, early previtellogenic oocytes, and some somatic interstitial cells. In contrast, the vitellarial areas are composed of more advanced oocytes, follicle cells surrounding the oocytes, and some interstitial cells, but no oogonia. A few larger previtellogenic oocytes rise up from each vitellarial area into the ovarian lumen. Each of these oocytes is still connected with its own vitellarial area by a partial extension of its follicle. Vitellogenesis takes place in these oocytes rising in the ovarian lumen. The ripe primary oocytes leave their follicles to be transported forward into the oviducts. Some phylogenetic implications of the basic characteristics in ovarian structure and oogenesis of E. nigricans are discussed. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/jmor.1052220302
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    Morphology of shells from viable and nonviable eggs of the chinese alligator (Alligator sinensis) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 103-110 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of eggshells from hatched eggs of captive Chinese alligators (Alligator sinensis) was compared with that of shells from eggs with early embryonic death and with the morphology of eggshells from the American alligator (Alligator mississipiensisis). Pieces of shells were examined in the scanning electron microscope. Parameters examined included: numbers of open pores on the outer surfaces, total shell thickness, and thickness of the outer densely calcified and inner mammillary layers. Results indicate that shells from Chinese and American alligator eggs with early embryonic death have a thicker outer densely calcified layer than do shells from hatched eggs or full-term embryos. Also, eggshells from Chinese alligator eggs with dead embryos have fewer open pores on the outer surface than do shells from hatched eggs, as has been reported earlier for the American alligator (Wink et al., '90). © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220110
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    Development of craniofacial musculature in Monodelphis domestica (marsupialia, didelphidae) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 149-173 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Development of craniofacial muscles of Monodelphis domestica (Marsupialia, Didelphidae) is described. In a period of 4-6 days all craniofacial muscles in M. domestica progress from myoblast condensation, to striated myofibers that are aligned in the direction of adult muscles and possess multiple, lateral nuclei. This process begins 1 to 2 days before birth and continues during the first few days after birth. Compared to other aspects of cranial development, muscle development in M. domestica is rapid. This rapid and more or less simultaneous emergence of craniofacial muscles differs from the previously described pattern of development of the cranial skeleton in marsupials, which displays a mosaic of acceleration and deceleration of regions and individual elements. Unlike the skeletal system, craniofacial muscles show no evidence of regional specialization during development. M. domestica resembles eutherian mammals in the relatively rapid and more or less simultaneous differentiation of all craniofacial muscles. It differs from eutherian taxa in that most stages of myogenesis occur postnatally, following the onset of function. The timing of the development of muscular and skeletal structures is compared and it is concluded that the relatively early development of muscle is not reflected by any particular acceleration of the differentiation or growth of skeletal structures. Finally, the difficulties in accounting for complex internal arrangements of muscles such as the tongue, given current models of myogenesis are summarized. © 1994 Wiley-Liss, Inc.
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    Ultrastructure of the ileum epithelium of Melipona quadrifasciata anthidioides (hymenoptera, apidae, meliponinae) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 191-201 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Study of the epithelial morphology of a stingless bee ileum from the pyloric valve to the last portion of high absorptive cells shows that although the bee ileum is an anatomically undifferentiated tube, four types of epithelial cells along the tube (in addition to the valve cells) indicate physiological differentiation. The anterior end seems to be less active in reabsorption, while the posterior region contains cells with typical morphology of an ion pump and permits conclusions about the mechanisms of absorption in the posterior end of the intestine. © 1994 Wiley-Liss, Inc.
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    Allometry of cetacean forelimb bones (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 215-221 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study examines the allometric scaling relationships of the cetacean humerus, radius, and ulna. Bone lengths and diameters were measured for 20 species of odontocete and three species of mysticete cetaceans, representing eight of the nine extant cetacean families. The scaling of individual bone proportions (bone length vs. cranio-caudal diameter, bone length vs. dorso-ventral diameter), and of individual bone dimensions against estimated body mass, are compared to models of geometric and elastic similarity. The geometric similarity model describes the scaling relationship of bone length vs. cranio-caudal diameter and body mass vs. cranio-caudal diameter for the humerus only; geometric similarity also describes the scaling relationship of body mass vs. bone length for all three bones. None of the scaling relationships fits the elastic similarity model. The scaling relationships of bone length vs. dorso-ventral diameter for all three bones, and bone length vs. cranio-caudal diameter for the radius and ulna, exhibit negative allometry, indicating that large bones are less robust than small bones. Negative allometry of structural support elements has not been previously described for terrestrial mammals or plants. The high relative swimming speeds of small delphinids may generate sufficient stresses to require more robust bones relative to those of larger whales. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220208
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    Spermatogenesis in the urodele Amhystoma dumerilii (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 287-299 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male reproductive cycle of this paedomorphic species that occurs only in Lake Pátzcuaro, Michoacán, México, was investigated by documenting changes in germinal cells during the spermatogenic cycle. Cysts of germ cells divide synchronously to complete spermatogenesis during September through December, with the proportion of evacuated cysts or cysts containing spermatozoa increasing during this period. The chromatin changes during prophase I of meiosis reveal the usual leptotene, zygotene, pachytene, and diplotene stages. A basal body at the caudal end of the spermatozoan head connects to the flagellum. After spermiation, empty cysts contain a granular substance. Spermatogenesis in this species follows an annual cycle like other north temperate salamanders, rather than the continuous spermatogenesis of some tropical salamanders. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220306
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    Effects of anisosmotic conditions on the cytoskeletal architecture of cultured PC12 cells (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 269-286 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: PC12 cells show a classical volume regulatory process when submitted to hypo-osmotic conditions. The present study examined the effects of such osmotic shock on the structural organization of different cytoskeletal elements. Results were obtained by use of different light and electron microscopy techniques combined with immunostaining methods. It appeared that the osmotically induced changes in cell volume were concomitant with important modifications in the organization of the microfilament network. Microfilaments concentrated in the perinuclear area, leaving only radial extensions of poorly organized structures in the cytoplasm. The latter were the only actin structures immunologically stained in the cytoplasm and seemed to anchor to the plasma membrane. Measurements of the fluorescence intensity of PC12 cells treated with FITC-labeled phalloidin indicated a progressive depolymerization, followed by a repolymerization of F-actin. This occurs in parallel with microfilament reorganization and volume regulatory processes. The appearance of microfilament reorganization was a function of both the incubation period and the amplitude of the osmolarity changes. During the first minutes of osmotic shock, a decrease was observed in the density and length of microvilli, which normally cover the PC12 cell surfaces, suggesting an early reorganization of the underlying microfilament network. Microtubules and intermediate filament networks were not affected by the hypo-osmotic conditions. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220305
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    Olfactory organ of acipenseriformes and comparison with other actinopterygians: Patterns of diversity (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 241-267 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The position and structure of the olfactory organ and its openings vary among actinopterygians. The anterior nasal opening is a simple perforation in the skin in many extant actinopterygians (e.g., acipenseriforms, lepisosteids, and primitive Recent teleosts) and represents the primitive condition. Polypterids and Amia each exhibit a derived condition, in which the anterior nasal opening extends into a tube. The olfactory organ is relatively far away from the anterior end of the elongate rostrum in acipenseriforms, whereas the olfactory organs are closer to the anterior end of the snout in extant actinopterygians (e.g., polypterids, lepisosteids, and amiids). In adults, olfactory organs are cuplike structures in most actinopterygians, but these organs are tubelike in polypterids. Among extant actinopterygians, a nasal diverticulum is present only in polypterids. Teleosts have accessory nasal sacs, but chondrosteans, polypterids, lepisosteids, and amiids lack them.The olfactory rosette is formed by primary folds or lamellae that may be placed anterior, lateral, posterior, and/or medial to the axis of the organ. Large acipenserids have 20-32 lamellae, polyodontids have 13-18 lamellae, lepisosteids have 8-10 lamellae, and Amia may have over 100. In teleosts, the number of lamellae varies from none or a few to over 200. Secondary lamellae are present in acipenseriforms, lepisosteids, and some advanced teleosts; secondary lamellae are interpreted as independently acquired in these lineages. Secondary lamellae are absent in Amia and primitive teleosts such as Elops and Hiodon. Tertiary lamellae are present in Acipenser oxyrhynchus. The arrangement of the primary lamellae in relation to the axis of the organ results in at least 11 patterns of the olfactory rosette in actinopterygians. Lamellae that are enclosed in a tubelike sac and that have an anteromedial diverticulum are specializations of polypterids. Primary lamellae anterior, lateral, and posterior to an elongate axis are characteristic of lepisosteids. The presence of primary lamellae lateral, medial, and posterior to an elongate olfactory axis is a synapomorphy of Halecomorpha (Amia plus teleosts). The absence of secondary lamellae is a synapomorphy of Halecomorpha. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220304
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    Negative growth control of mitotically active imaginal cells (histoblasts) of the abdominal epidermis during metamorphosis of the houseflyWe dedicate this paper to the memory of our graduate school mentor, Professor P. Govindan, Annamalai University, Tamil Nadu, India. (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 301-307 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: On the ventral side of each pupal abdominal segment of the housefly, there is a pair of histoblast nests, each containing about 600 diploid cells. These cells, during adult development, divide, replace intervening polytene larval epidermal cells (LEC), and form both the median sternite and the surrounding pleura of the adult segment. Since the histoblast nests and the LEC form a contiguous layer, we examined the role of these two types of cells in regulating the mitotic potential of the histoblasts during development of the median sternite. Two experimental approaches were used: deletion of one of the nests by thermocautery; and by disturbance of the continuity of the monolayered epidermis by thermocautery of, or topical application of heptanol on, the midventral LEC. Ablation of one of the contralateral nests resulted in a mirror image duplication of the hemisternite and pleura by the surviving nest. Disturbance of the continuity of the LEC produced mirror image duplication of the hemisternal pattern by each of the contralateral nests. From these results, we propose that the contralateral ventral nests mutually downregulate their mitotic potential by secreting regulatory factor(s) to produce the normal median sternite pattern and surrounding pleura. We also suggest that these chemicals act in a paracrine fashion, possibly through gap junctions in the LEC. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220307
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    Locomotor analysis of surface propulsion by three species of reduced-limbed fossorial lizards (Lerista: Scincidae) from western australia (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 309-326 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relatively large, but superficially similar, Lerista macropisthopus, L. connivens, and L. lineopunctulata differ in bodily elongation and limb reduction, inhabit sandy areas, and move under sand. Visual analysis and computer-generated excursion and curvature graphs show that each species moves differently on smooth and rough surfaces, on surfaces with and without nails, and in channels.The reduced-limbed quadruped, Lerista macropisthopus walks frequently, using its four clawed limbs, whenever traction is available. Its undulating body curves uniformly but never generates slide-pushing curves. The biped L. connivens walks with its hindlimbs, although less frequently, and/or oscillates its tail in propelling its relatively stiff, short body. The biped L. lineopunctulata rarely uses its hindlimbs but always undulates body and. tail. It can use single nails in cam-follower progression. L. macropisthopus and L. connivens walk well in channels with rough bottoms, but only L lineopunctulata uses tunnel concertina to travel in channels with smooth bottoms.Friction of body surfaces dragged and of those transmitting propulsive forces is critical to these lizards and explains the division of movement into slow and rapid progression rates. Animals that have clawed limbs, no matter how reduced, use them. Body and tail generally are used differently. The tail may be flipped anteriorly to facilitate concertina. In nail arrays, travel is by simple, never by lateral, undulation. Apparently distinct motor coordination patterns are associated with differences in morphology, habit, and habitat. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jmor.1052220308
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