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  • Cambridge University Press (CUP)  (7)
  • 1975-1979  (7)
Type of Medium
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  • Cambridge University Press (CUP)  (7)
Language
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  • 1975-1979  (7)
Year
Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  International Astronomical Union Colloquium Vol. 31 ( 1976), p. 135-139
    In: International Astronomical Union Colloquium, Cambridge University Press (CUP), Vol. 31 ( 1976), p. 135-139
    Abstract: Increased sophistication in both, direct impact detectors and zodiacal light measurements encourages to discuss the compatibility of the results obtained by these quite different methods of investigating interplanetary dust. Taking recent measurements of particle fluxes and velocities obtained by the space missions of Pioneer 8/9 (Berg and Grün 1973), Heos 2 (Hoffmann et al. 1975), and comparing them with submicron-sized craters on lunar surface samples (Schneider et al. 1973, Fechtig et al. 1974) there seem to be two types of interplanetary dust populations: larger ( 〉 10 −12 g) micrometeorites orbiting around the sun as the classical zodiacal dust cloud and a second component of very small ( 〈 10 −12 g) particles coming radially from the direction of the sun with high velocities ( 〉 50 km/s). On the basis of the flux data referred to above and adopting for both components velocities of 10 or 50 km/s relative to the detector, respectively, a differential distribution function n(a) · da was found for the particle radii (a) as shown at a logarithmic scale in fig. 1. A density of 3 g/cm 3 was adopted in order to convert particle masses into radii. The regions A, B, C (see Table 1) correspond approximately to the regimes of “submicron particles”, the classical zodiacal cloud particles, and the meteoritic component of the interplanetary dust complex. From this information the brightness I(ε) of the zodiacal light in the ecliptic plane can be computed as a function of elongation by approximating the distribution function n(a) in the different regions by simple power laws a −k ·da and by adopting a resonable scattering function σ(θ) for the average scattering behaviour of one particle of the mixture depending on the scattering angle θ. By use of an inverse (v = 1) decrease of particle number densities n = n o · r −v with solar distance r(AU), where n o is the number density at r=1 AU, one obtains with a particle size distribution law n(a)da ~ a −k da in the different intervals of sizes (Table 1) the intensity of the zodiacal light (in stars of 10th magnitude per square degree, S 10 ) as shown in fig. 2. The two models (Maximum, Minimum) correspond to an upper and to a lower limit of particle number densities compatible with the in situ measurements, respectively.
    Type of Medium: Online Resource
    ISSN: 0252-9211
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
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  • 2
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  The Journal of Hellenic Studies Vol. 96 ( 1976-11), p. 46-69
    In: The Journal of Hellenic Studies, Cambridge University Press (CUP), Vol. 96 ( 1976-11), p. 46-69
    Abstract: The Achaean war against Rome in 146 continues to provoke befuddlement and perplexity. Few problems in antiquity have proved so intractable to solution. The event was of major import: the last futile outburst of Greek resistance to Roman power, calling forth a new era, an enforced reorganisation of Greece and its subjugation, for all practical purposes, to the Roman governor of Macedon. Greek independence was thereafter chimerical. Yet the origins and motivations for that fateful struggle remain as puzzling as ever. Understandably so. A half century earlier, the Achaean League had thrown off allegiance to Macedon and opted for collaboration with Rome. A formal alliance followed in subsequent years. Relations between the two powers were sometimes rocky, but never issued in overt conflict during that half-century. In the three great eastern wars of the second century, against Philip V, Antiochus III, and Perseus, Rome and Achaea were on the same side. Yet in 146, when Rome's military might should have been incontestable, the Achaeans engaged her in a suicidal and ruinous war that brought the dissolution of the old League and the overlordship of Rome. Small wonder that the episode causes bafflement.
    Type of Medium: Online Resource
    ISSN: 0075-4269 , 2041-4099
    RVK:
    RVK:
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
    detail.hit.zdb_id: 2067299-8
    SSG: 6,14
    SSG: 6,12
    SSG: 6,11
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  • 3
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1975
    In:  The Classical Quarterly Vol. 25, No. 1 ( 1975-05), p. 58-81
    In: The Classical Quarterly, Cambridge University Press (CUP), Vol. 25, No. 1 ( 1975-05), p. 58-81
    Abstract: Ancient Rhodes reached a pinnacle of power in the early second century B.C. For twenty years—from Apamea to Pydna—her fleet was unrivalled in the Aegean and her mainland possessions encompassed most of Lycia and Caria. Ally and helpmate of Rome in the war on Antiochus III, Rhodes gained much profit from the association, in prestige and territorial acquisitions. But her heyday was brief, her fall swift and calamitous. After Pydna, Rhodes felt the heavy hand of Rome: she forfeited most of her mainland holdings; her economy suffered ruinous setback; the island republic was humbled and humiliated. So dramatic a reversal of fortune demands explanation.
    Type of Medium: Online Resource
    ISSN: 0009-8388 , 1471-6844
    RVK:
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1975
    detail.hit.zdb_id: 2060299-6
    SSG: 6,12
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  • 4
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  International Astronomical Union Colloquium Vol. 31 ( 1976), p. 159-163
    In: International Astronomical Union Colloquium, Cambridge University Press (CUP), Vol. 31 ( 1976), p. 159-163
    Abstract: For the first time in situ measurements of interplanetary dust have been performed between 0.3 AU and 1 AU from the sun by the micrometeoroid experiment on board Helios A. The measured particle masses are between 10 −15 g and 10 −8 g and their measured speeds are between 2 km/sec and 20 km/sec. Particle impacts are identified by the time-of-flight spectra of the ions released upon impact. 15 large particles (m ≥ 10 −12 g) were detected from Dec. 15, 1974 to Sept. 5, 1975. They show a strong increase of the impact rate (appr. a factor of 10) between 1 AU and 0.3 AU. The directions from which they impacted the sensor are concentrated between the solar direction and the apex direction of the Helios spacecraft.
    Type of Medium: Online Resource
    ISSN: 0252-9211
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
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  • 5
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  International Astronomical Union Colloquium Vol. 31 ( 1976), p. 164-164
    In: International Astronomical Union Colloquium, Cambridge University Press (CUP), Vol. 31 ( 1976), p. 164-164
    Abstract: The composition of the impact-plasma, produced by dust particles hitting an Au-target was measured, using a model of the HELIOS-mlcrometeoroid-detector. The 2 MV dust accelerators of the MPI für Kernphysik, Heidelberg, and the NASA Ames Research Center were used to accelerate particles consisting of Al, Al 2 O 3 , SiO 2 , Soda-Lime-Glass, Polystyrene and Kaolin to velocities between 2 km/sec and 15 km/sec. Fe-projectiles could be accelerated up to 40 km/sec. The masses of the dust grains were between 10 −15 g and 3 × 10 −10 g. The experiments showed, that because of the characteristic features of the measured spectra it is possible to separate noise events from impacts even at a high noise background. The smallest particles (m 10 −15 g) triggering the experiment produce spectra well above the noise level (more than a factor 10) because of the high sensitivity of the ion-detector (multiplier).
    Type of Medium: Online Resource
    ISSN: 0252-9211
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
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  • 6
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  International Astronomical Union Colloquium Vol. 31 ( 1976), p. 334-338
    In: International Astronomical Union Colloquium, Cambridge University Press (CUP), Vol. 31 ( 1976), p. 334-338
    Abstract: During a period of 60 days around the time when the HEOS 2 satellite penetrated the orbital plane of Comet Kohoutek (1973f) the micro-meteoroid experiment on board registered an excessive particle flux. These particles are identified with those originated in Comet Kohoutek. Orbit calculations show that their emission occurred outside 3.8 AU from the sun. The ratio of the force of radiation pressure to that of gravity of these particles was determined to ß =1 ± 0.1, their mass has been measured from the satellite data (10 −13 g to 10 −11 g). The velocity and the rate of dust particles emitted from the comet is studied on the basis of the theory of dust comets formulated by Finson and Probstein. An emission rate of appr. 1.2 × 10 18 particles per second in the size range corresponding to 0.9 ≤ ß 〈 1.1 and an emission velocity of appr. 0.5 km/sec match best the observed data.
    Type of Medium: Online Resource
    ISSN: 0252-9211
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
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  • 7
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1976
    In:  International Astronomical Union Colloquium Vol. 25, No. Part2 ( 1976), p. 949-961
    In: International Astronomical Union Colloquium, Cambridge University Press (CUP), Vol. 25, No. Part2 ( 1976), p. 949-961
    Abstract: The HEOS 2 satellite was launched into a highly eccentric orbit around the earth on January 31, 1972 and re-entered the earth’s atmosphere after a successful mission on August 2, 1974. Due to the orbit (apogee: 240 000 km, perigee: 300 – 5000 km) the satellite spent most of the time in the interplanetary region where the influence of the earth’s gravitation field is negligible with regard to its effect on interplanetary dust particles.
    Type of Medium: Online Resource
    ISSN: 0252-9211
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1976
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