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  • 1985-1989  (4)
  • 1986  (4)
Material
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  • 1985-1989  (4)
Year
  • 1
    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
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 821-836 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 2569-2579 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 324 (1986), S. 463-471 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary This review presents selected aspects of atomic spectroscopy as used for the determination of elements in biological materials. The analytical techniques considered include sample preparation and element speciation, flame, furnace and plasma based methods for the determination of elements and analytical accuracy. Temporal trends in instrumentation and technique usage and in the elements determined are examined. It is concluded that techniques are available to determine most of the elements of current biological interest, the greatest challenge lies in identifying their biological function.
    Notes: Zusammenfassung Dieser Überblick gibt ausgewählte Gesichtspunkte bei der atomspektroskopischen Bestimmung von Elementen in biologischem Material wieder. Die betrachteten Analysentechniken umfassen Probenvorbereitung und Speziation von Elementen, Flammen-, Ofen- und Plasmamethoden zur Elementbestimmung sowie die Frage der analytischen Richtigkeit. Weiterhin werden Entwicklungstendenzen beim Einsatz verschiedener Instrumentierungen und Techniken sowie bei der Auswahl der untersuchten Elemente aufgezeigt. Als Schlußfolgerung ergibt sich, daß mit den verfügbaren Methoden die Mehrzahl der biologisch interessanten Elemente bestimmt werden kann; dabei liegt die größte Herausforderung in der Aufklärung ihrer biologischen Wirkung.
    Type of Medium: Electronic Resource
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