536 research outputs found
Contributions to the odontological study of living Chondrichthyes: 1. The genus <i>Alopias</i> Rafinesque, 1810
Contributions to the odontological study of living Chondrichthyes: 3. The genus <i>Isistius</i> Gill, 1864
Carbon-poor solar flare events
Energetic particle flux enhancements over the period October 1973 - December 1977 were surveyed using ULET sensor on the IMP-8 spacecraft. During the four year period the most extreme periods of Fe enrichment compared to oxygen were during solar flare events in February 1974 and May 1974. In these same events, the carbon abundance with respect to oxygen was significantly depleted when compared with a value C:0 is approximately 0.45:1 for typical solar flares. These observations, taken together with previously reported He-3 enrichment in these events, give strong evidence for the importance of a wave-particle interaction in the pre-injection heating of the ambient matter
Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites in living supra-specific taxa of Chondrichthyan fishes. Part B: Batomorphii. 4a: Order Rajiformes - Suborder Myliobatoidei - Superfamily Dasyatoidea - Family Dasyatidae - Subfamily Dasyatinae - Genera: <i>Amphotistius, Dasyatis, Himantura, Pastinachus, Pteroplatytrygon, Taeniura, Urogymnus</i> and <i>Urolophoides</i> (incl. supraspecific taxa of uncertain status and validity), Superfamily Myliobatoidea - Family Gymnuridae - Genera: <i>Aetoplatea</i> and <i>Gymnura</i>, Superfamily Plesiobatoidea - Family Hexatrigonidae - Genus: <i>Hexatrygon</i>
Part B of this series, comprising the Batomorphii is continued with taxa of the Myliobatoidei. The tooth morphology of representatives of eight genera (incl. supraspecific taxa of uncertain status and validity) of the family Dasyatidae, two of Gymnuridae and one of Hexatrygonidae is described and illustrated by SEM-photographs. A differential diagnosis for a final conclusions on myliobatoid odontology will be given in a forthcoming issue dealing with the last myliobatoid taxa
Spatial dependence of the local diffusion coefficient measured upstream of the November 12, 1978 interplanetary traveling shock
Characteristics of wuprathermal particles accelerated by quasi-parallel interplanetary traveling shocks have been generally explained in terms of a first order Fermi mechanism. Such models require diffusive scattering of particles upstream of the shock. This scattering is characterized by a local diffusion coefficient, kappa, which is determined by the local power density of waves in the upstream region. The dependence of the diffusion coefficient of suprathermal upstream protons on distance from the November 12, 1978 interplanetary traveling shock using a different approach is studied. Unlike previous studies this method, which is based on measurements of particle streaming and intensity gradients, does not rely on predictions. The local spatial variations of Kappa upstream of the November 12, 1978 shock have been chosen for study because the characteristics of this quasi-parallel shock have been extensively studied, and also because of its favorable geometry (i.e. B field nearly radial)
Post-shock spikes: A new feature of proton and alpha enhancements associated with an interplanetary shock wave
Abrupt and prolonged enhancements in the intensities of 100 to approximately 2000 keV nucleon protons and alpha particles observed in interplanetary space are interpreted as particle populations confined between an interplanetary shock front and a magnetic field discontinuity. Prominent intensity spikes observed only below approximately 400 keV per charge for both protons and alpha particles several hours behind the shock front suggest that some fraction of the confined particles is accelerated by an energy per charge dependent process
Iron charge states observed in the solar wind
Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream
The heavy ion composition in 3HE-rich solar flares
The 3He-rich flares show a tendency to be enriched in heavy ions, and that this enrichment covers the charge range through Fe. The discovery of this association was responsible, in part, for the discarding of 3He enrichment models which involved spallation or thermonuclear reactions, since such models were unable to produce heavy nuclei enhancement. Results of a survey of heavy nucleus abundances observed in 66 3He-rich flares which occurred over the period October 1978 to June 1982 are presented
Observation of pick-up ions in the solar wind: Evidence for the source of the anomalous cosmic ray component?
Singly ionized energetic helium has been observed in the solar wind by using the time of flight spectrometer SULEICA on the AMPTE/IRM satellite between September and December, 1984. The energy density spectrum shows a sharp cut off which is strongly correlated with the four fold solar wind bulk energy. The absolute flux of the He(+)ions of about 10000 ion/sq cm.s is present independent of the IPL magnetic field orientation. The most likely source is the neutral helium of the interstellar wind which is ionized by solar UV radiation. It is suggested that these particles represent the source of the anomalous cosmic ray component
Temporal variations of the anomalous oxygen component, 1977 - 1984
A survey is of the long term temporal variations of 6.6 to 12 MeV/nucleon anomalous oxygen at 1 AU covering the period 1977 to 1984. This time interval included the recent solar maximum, with the recovery at neutron monitor energies beginning in 1982. During this time interval, 6.6 to 12 MeV/nucleon 0 fluxes decreased by at least a factor of 50, and indeed remained below the instrumental detection threshold after 1979. By late 1984, neutron monitors had recovered to roughly 1979 levels from the 1982 solar maximum, and anomalous O still remained below the detection threshold
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