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  • Springer  (8)
  • 1975-1979  (8)
  • 1977  (8)
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  • 1975-1979  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Manuscripta mathematica 22 (1977), S. 87-103 
    ISSN: 1432-1785
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This note continues the investigations of Knebusch on algebraic curves over real closed fields and was initiated by reading [3]. Especially we ask for the existence of real algebraic functions with given zeroes and poles, a question going back to Witt [4]. We study the real nature of coverings of real algebraic curves, and if the covering has degree two, we get algebraic proofs for results, which in the classical case have been obtained by topological methods in [2].
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mathematische Annalen 228 (1977), S. 101-111 
    ISSN: 1432-1807
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 50 (1977), S. 261-270 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung An der Erythrocytenmembran wird die Beziehung zwischen anisotroper Toluidinblaufärbung und Membranstruktur untersucht. Enzymatischer oder chemischer Abbau der Glykokalyx stört die topo-optische Färbung. Eine Abschwächung wird auch durch Digitoninbehandlung Glutaraldehyd-fixierter Zellen erzielt. Durch Chloroform-Methanol-Inkubation wird die anisotrope Toluidinblaufärbung gelöscht, aber sie kann nach Aldehyd-Bisulfitbildung wieder nachgewiesen werden. An agglutinierten Erythrocyten ist die Wirkung einer Chloroform-Methanol-Behandlung stark eingeschränkt. Die reversibel kollabierte Glykokalyx zeigt keine topo-optische Färbung. Die Befunde werden als Hinweis auf die Bedeutung der räumlichen Orientierung der Glykoproteine an der Zelloberfläche gedeutet. Störungen im Aufbau der Glykokalyx durch Hydrolyse bzw. Verlust oder durch Umverteilung von Komponenten verändern die Bedingungen für die anisotrope Toluidinblaufärbung. Eingriffe an der Lipidschicht können mit solchen Veränderungen einhergehen; für die Interkalation von Farbstoffmolekülen in die Lipidschicht ergab sich jedoch kein Anhalt. Die topo-optische Färbung mit Toluidinblau wird auf Grund dieser Ergebnisse als geeignetes Verfahren zur Untersuchung der Glykokalyx von Erythrocyten (und vermutlich auch anderer Zellen) angesehen.
    Notes: Summary The study was concerned with the molecular structure of the erythrocyte membrane and its anisotropic staining with toluidine blue. Enzymatic or chemical degradation impairs the topo-optical staining. Decreased anisotropy results also from digitonin treatment of glutaraldehyde fixed cells. Incubation in a mixture of chloroform and methanol abolishes the anisotropic staining with toluidine blue, but it has been restored by the aldehyde bisulfite-procedure. The efficacy of a treatment with chloroform-methanol is greatly reduced in the case of agglutinated erythrocytes. The reversibly collapsed glycocalyx is devoid of topo-optical staining. The findings refer to the spatial orientation of glycoproteins at the cell surface. Degradation or loss and rearrangement, respectively, change the glycocalyx structure and likewise deteriorate the conditions for the anisotropic staining. Alterations of the lipid layer of the membrane may result in similar effects. There was, however, no indication of an intercalation into the lipid layer of dyestuff molecules. In conclusion, the topo-optical toluidine blue staining is considered a powerful method aiding studies of the glycocalyx of erythrocytes (and presumably of other types of cells too).
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 48 (1977), S. 137-144 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the erratic changes of the orbital period, which are observed in some detached eclipsing binary systems, cannot be interpreted as real if their light curves show changing anomalies with asymmetric minimum profiles. In this case the photometrically determined times of the minima do not coincide with the ideal geometric ones, which are unobservable. This fact and the applied reduction methods for deriving the photometric times of minima cause systematic period errors of cumulative character. The discussion of six photoelectrically-determined minima obtained within the last 20 yr, and earlier photographic ones of the 0d.479 period eclipsing binary XY UMa yields a constant period. The long cyclic light curve variations due to starspot activity of the larger and hotter component of this system are reflected in corresponding period oscillations.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 52 (1977), S. 351-356 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract On three nights in February 1976 we carried out polarimetric measurements, in V, of the short periodic eclipsing binary XY UMa, covering a complete cycle. The results are as follows: (1) Within all phase intervals the linear polarization does not exceed 0.1%. (2) In the phase range 0 p .95–1 p .35 the scatter of the Stokes parametersQ andU is about twice that within the phase interval 0 p .35–0 p .95. (3) A periodogram analysis of these data revealed a period of 21000 s, which is equal to half the orbital periodP o=0d.47899 within 1.5%. From these we derive the conclusions that no circumstellar envelope can be made responsible for the observed long-term changes of the light curve and system brightness, supporting the earlier spectroscopic finding. The different scatter of the Stokes parameters at different phase intervals and theP o/2 periodicity are in favor of the star spot model for XY UMa proposed by one of the authors (E. G.).
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  • 6
    Publication Date: 1977-05-01
    Print ISSN: 0004-640X
    Electronic ISSN: 1572-946X
    Topics: Physics
    Published by Springer
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  • 7
    Publication Date: 1977-12-01
    Print ISSN: 0004-640X
    Electronic ISSN: 1572-946X
    Topics: Physics
    Published by Springer
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  • 8
    Publication Date: 1977-01-01
    Print ISSN: 0018-2222
    Electronic ISSN: 1432-119X
    Topics: Biology , Medicine
    Published by Springer
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