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  • 1
    Electronic Resource
    Electronic Resource
    Subcellular Pathology of Human Neurodegenerative Disorders: Alzheimer-Type Dementia and Huntington's Disease (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Activities of enzyme markers of subcellular organelles have been measured in brain tissue from subjects with Alzheimer-type dementia (ATD) and Huntington's disease (HD). Significant increases in the activity of the lysosomal enzyme β-glucuronidase were observed in both ATD temporal cortex and HD putamen. It is suggested that β-glucuronidase activity may be a useful biochemical indicator of cellular damage in the CNS. A significant reduction in neutral α-glucosidase activity was observed in ATD temporal cortex and HD putamen. This change may reflect an alteration in glycoconjugate processing and may relate to the susceptibility of neurones to the degenerative processes of ATD and HD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb00693.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Self-consistent study of a perpendicular collisionless and nonresistive shock (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 1767-1788 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Particle dynamics and field behavior associated with a perpendicular collisionless supercritical and viscous shock are investigated by use of numerical simulation. A one-dimensional, relativistic, fully electromagnetic and nonperiodic particle simulation code (for both electrons and ions) is used where self-consistent space-charge effects and induced effects are totally included. The principal field patterns of the shock (trailing wave train, ramp, and foot region) are studied in detail and are shown to have scale lengths mainly dictated by ion dynamics; the behavior of the corresponding plasma currents associated with the different field components is also presented. Ions are shown to suffer successive "acceleration–trapping–detrapping'' at the shock front, and locally in the trailing wave train of the downstream region through combined effects of the electrostatic and magnetic fields. While detrapped, the reflected ions describe very large Larmor orbits and cause a ring distribution; a large rapid nonstochastic ion heating results from this ion gyration. This heating (resistivity-free) is the main source of dissipation and is responsible for large field damping. Competitive effects such as particle stochasticity, particle trapping, wave damping, wave overtaking, and dispersion effects are shown to interact with each other and to affect the overall dissipation mechanism. Comparison with previous works is also discussed. Various Mach number situations are considered, leading to the definition of a transitory regime between subcritical and supercritical regimes and of a corresponding critical threshold of the electrostatic field. In contrast with the supercritical regime, the subcritical regime is characterized by a low density of trapped-reflected ions, a broad ion distribution function with a weak tail, and a weak adiabatic bulk ion heating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866191
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  • 3
    Electronic Resource
    Electronic Resource
    Self-consistent plasma heating and acceleration by strong magnetosonic waves for θ=90 °. Part I: Basic mechanisms (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 821-836 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The behavior of strong magnetosonic waves propagating perpendicular to a static field B0 is investigated within the frequency range ωci〈ω〈ωlh; ωci,ω, and ωlh are, respectively, the ion cyclotron, the pump wave, and the lower-hybrid frequencies. A one-dimensional, relativistic, fully electromagnetic, particle simulation code (for both electrons and ions) is used, where self-consistent effects are totally included. During the buildup phase, a longitudinal electric field develops and attains a nonlinear level which strongly distorts its shape so that many harmonics are produced. This is followed shortly by ion trapping, which simultaneously enhances the wave overtaking (the wave crests overtaking the wave troughs) and produced a strong wave damping. A very large ion acceleration accompanied by a strong heating (mainly nonstochastic) perpendicular to B0 results; the electrons exhibit only poor heating associated with their adiabatic compression. The dynamics of both particle species, the consequences of the wave–particle energy transfer and the particle viscosities, are studied in detail. Competitive and self-consistent effects such as space-charge effects, wave overtaking, ion trapping, and wave damping are investigated and compared with previous models; the mechanisms by which these various phenomena interact on each other are analyzed. Characteristics of nonstochastic and stochastic ion heating are also discussed. Our computations show that if sufficient intensity is reached, one is not constrained to use lower-hybrid waves or cyclotron harmonic waves to heat a plasma efficiently and that any frequency below ωlh can be used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865939
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Plasma heating through a supercritical oblique collisionless shock (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 1110-1114 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron and ion dynamics are investigated through particle simulation of a supercritical oblique collisionless shock. As θ deviates from 90°, ions are accelerated and trapped in the electrostatic wells and later become detrapped; this results in strong ion heating perpendicular to B0. Below a critical angle θte electrons are strongly energized along B0, and heated. A large parallel electron current builds up and induces new transverse electromagnetic components in the ramp of the shock. For weaker angles, ion heating vanishes below a second critical angle θti.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866309
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  • 5
    Electronic Resource
    Electronic Resource
    Stability of the low-frequency hot-electron interchange mode for a bumpy torus simulation model (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 3237-3244 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The parametric dependence of the growth rate of the low-frequency hot-electron interchange mode is studied with a two-and-a-half-dimensional relativistic electromagnetic particle code that models the geometry of a bumpy torus. The simulation results are compared in detail with finite-Larmor-radius theory, as well as zero-Larmor-radius theory. For the long-wavelength modes, the growth rates measured in the simulations tend to agree with those predicted from zero-Larmor-radius theory. For short-wavelength modes, the stabilizing effects of finite Larmor radius are significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866498
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Relativistic particle dynamics in a steepening magnetosonic wave (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1001-1010 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Acceleration of both electrons and ions to relativistic energy by large amplitude magnetosonic waves is investigated by use of numerical simulation. Nonlinear effects are shown to form the saturation mechanism and limit the amplitude below the level where a particle specie can undergo unlimited acceleration, which is expected theoretically. Spiky structures appear both in density and field waveforms that are characteristics of the relativistic regime. Both electrons and ions are strongly accelerated by Elx×Bz drift and Ety field, but their resonance features versus fields are strongly different. Around the trapping time, relativistic electron solitonlike wavelets are triggered from the main wave ramp; a few mechanisms are proposed for their interpretation. Both electrons and ions are strongly heated at the expense of the wave energy. This damping in association with the large space charge effects resulting from the spiky structures is the origin of some observed saturation level in the field energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859021
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  • 7
    Electronic Resource
    Electronic Resource
    Electrostatic instabilities of velocity-space-shell distributions in magnetized plasmas (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 2569-2579 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron instabilities of magnetized spherical shell distributions in velocity space with a colder Maxwellian background are investigated analytically with simulations using electrostatic particle codes. The resonant and nonresonant instabilities observed in the particle simulations are in agreement with zeros of the dielectric function, as found from the resonant approximation for waves with an electric field component along the magnetic field or by computation with a root solver code in the case of perpendicular propagation. Saturation of the instabilities is by nonlinear cyclotron resonance with the cold background in the resonant case or by nonstochastic cyclotron harmonic damping by the cold background in the nonresonant case. Instabilities invariably lead to perpendicular acceleration and heating of the cold background to velocities sometimes exceeding the shell velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865549
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  • 8
    Electronic Resource
    Electronic Resource
    Erratum: "Electrostatic instabilities of velocity-space-shell distributions in magnetized plasmas'' [Phys. Fluids 29, 2569 (1986)] (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 1575-1575 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866530
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  • 9
    Electronic Resource
    Electronic Resource
    THE OCULAR FUNDUS OF TWO CETACEANS (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 3 (1987), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We provided a water-cornea interface to correct the usual aerial myopia encountered in fundus photography of marine mammal eyes. The 12 Tursiops eyes were consistent for vascular structure, optic papillae, dimensional components and tapetal coloration. Multiple photographs were assembled to produce one ocular fundus typical of Tursiops truncatus and one for Grampus griseus. The eyes have a vestigial hyaloid vessel and an optic disc („blind spot”) that occupies the center of the fundus. The disc is bounded in both species by a vascular structure that is continuous with a (retrobulbar) perineural organ called the ophthalmic rete. The vascular trees of the fundus do not suggest an area of specialization for high resolution. Both species exhibit total tapetalization. Tapetal spectral reflectance did not vary between Tursiops. There was, however, a difference between species in the short wavelength regions of the spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1987.tb00147.x
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  • 10
    Electronic Resource
    Electronic Resource
    Metasomatised and veined upper-mantle xenoliths from Pello Hill, Tanzania: evidence for anomalously-light mantle beneath the Tanzanian sector of the East African Rift Valley (1988)
    Springer
    Contributions to mineralogy and petrology 100 (1988), S. 510-527 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Peridotite xenoliths from the Pello tuff cone in the Rift Valley of northern Tanzania, bear witness to upper mantle veining and metasomatism. Veins of katungite composition, with an asthenospheric signature, have imposed K, Fe, Ti, OH and REE metasomatism upon previously depleted peridotite. Chemical and mineralogical gradients are present in the peridotite wall rocks, and hydrous phases developed in the peridotite are generally lower in Ti and Fe, but higher in Mg and Cr, than those in the veins. The metasomatism has reduced the density of affected peridotite by up to 4.5%, supporting earlier geophysical models for low-density mantle beneath the Rift Valley. Age constraints for the metasomatically-induced density decrease permit correlation with Recent faulting in the Rift Valley, but not with the major upwarp of the Kenya Dome in the late Tertiary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371380
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