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  • 2005-2009  (1)
  • 1990-1994  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Changes in reproductive physiology and behaviour over the nesting cycle in male three-spined sticklebacks (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 66 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plasma 11-Ketotestosterone (11 KT) and testosterone (T) levels and spiggin-mRNA levels, as well as the kidney-somatic index (IK) were measured in sexual males and in paternal males at the middle (5 days paternal) and at the end (8 days paternal with hatched eggs) of the nesting cycle in three-spined sticklebacks Gasterosteus aculeatus from two populations. Glueing (using threads of 11 KT induced kidney-protein spiggin) and fanning behaviour was measured daily. Fanning increased in paternal fish and remained low in sexual males. Plasma 11 KT and T levels, on the other hand, declined significantly in parental compared to sexual males as did spiggin expression, IK and glueing behaviour. Thus, the drastic decrease in circulating 11 KT levels during the later parental phase may have resulted in an energy-saving decrease in spiggin-production and glueing, when this was no longer needed for nest maintenance. In addition, the mRNA levels of the β-subunits of both gonadotropins, luteinising hormone (LH) and follicle stimulating hormone (FSH) were measured. The expression of both gonadotropins declined in the parental phase (not significant for β-FSH in one of the populations) which was consistent with a decline in androgen levels possibly controlled via decreased gonadotropin secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00691.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Photofission of235U and238U at intermediate energies: absolute cross sections and fragment mass distributions (1994)
    Springer
    The European physical journal 350 (1994), S. 249-261 
    Details
    ISSN: 1434-601X
    Keywords: 25.20.Dc ; 25.85.Jg ; 27.90.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The total photofission cross section σγ,F for235U and238U has been measured in the energy range 50≤E γ≤800 MeV at the 855 MeV Mainz Microtron MAMI using energy and time tagged photons (Glasgow Tagger) and a 4π arrangement of position sensitive fragment detectors. Besides the absolute photofission cross section σγF , which almost completely exhausts the total photon absorption cross section for these nuclei, fragment mass distributions in this energy domain were determined via time of flight techniques (TOF). The results for the total photofission cross sections σγ,F normalized to the atomic numberA for both isotopes coincide, and agree in theΔ-resonance region, within the systematic errors, with the socalled“Universal Curve” σγ,T /A of the total photon absorption cross section σγ,T . At higher energies the cross sections exhibit a smooth behaviour. In particular, it is shown for the first time that there isno resonance-like shape near the D13 resonance (at ≈710 MeV) as observed for the free proton. This complete suppression of the D13 resonance in complex nuclei is not yet understood on a microscopic level. The fragment mass distributions show a predominantly mass symmetric fission. However, contributions from mass asymmetric fission at some photon energies may give a hint of an increased mass asymmetric fission after the onset of the pion and two pion channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289589
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Control of plant growth by nitrogen and phosphorus in mesotrophic fens (1991)
    Springer
    Biogeochemistry 12 (1991), S. 135-148 
    Details
    ISSN: 1573-515X
    Keywords: fens ; management ; nitrogen ; phosphorus ; productivity ; vegetation ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A fertilization experiment was carried out in 3 mesotrophic fens to investigate whether plant growth in these systems is controlled by the availability of N, P or K. The fens are located in an area with high N inputs from precipitation. They are annually mown in the summer to prevent succession to woodland. Above-ground plant biomass increased significantly upon N fertilization in the two “mid”-succession fens studied. In the “late”-succession fen that had been mown for at least 60 years, however, plant biomass increased significantly upon P fertilization. The mowing regime depletes the P pool in the soil, while it keeps N inputs and outputs in balance. A long-term shift occurs from limitation of plant production by N toward limitation by P. Hence, mowing is a suitable management tool to conserve the mesothrophic character of the fens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001811
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    Paper (German National Licenses)
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