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  • Digitale Medien  (6)
  • Engineering General  (3)
  • Pituitary  (3)
  • 1
    ISSN: 1432-0878
    Schlagwort(e): Serotonin (5HT) ; Platyfish ; Immunochemistry ; Brain ; Pituitary
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Immunoreactive serotonin (ir-5HT) containing cells were localized in the brain and pituitary gland of the platyfish by use of immunoperoxidase procedures. In the brain, ir-neurons were found lining the wall of the third ventricle and in its lateral and posterior recesses. More caudally, ir-perikarya were found in the valvular portion of the cerebellum and in the raphe region. Ir-5HT was also localized within the pineal gland in fish that had been sacrificed before 1:00 p.m. Within the pituitary gland, ir-5HT was localized in periodic acid Schiff-positive cells of the pars intermedia of all fish while, in only a few animals, less intense immunoreactivity was also present in gonadotrops of the caudal pars distalis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0878
    Schlagwort(e): Brain ; Pituitary ; Gonad ; Androgens ; Platyfish, Xiphophorus maculatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary This report demonstrates that the administration of testosterone (T) or 11-ketotestosterone (11-KT) to sexually immature (8 wks old) male platyfish (Xiphophorus maculatus) of early-and late-maturing genotypes affects the synthesis and/or release of luteinizing hormone-releasing hormone (LHRH), as assessed by immunocytochemical evaluation, increases the number and activity of pituitary gonadotropes, stimulates the production of sperm and, thus, advances the age of sexual maturation over that dictated by the genome. We also show that 11-KT and T affect different LHRH-containing centers in the brain and have differential effects on rate and degree of sexual maturation, regardless of whether the hormones are administered to early or late-maturing genotypes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0878
    Schlagwort(e): Neuropeptide Y ; Dynorphin ; Brain ; Pituitary ; Sexual maturation ; Xiphophorus maculatus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Immunoreactive neuropeptide Y and dynorphin have been localized in the brain and pituitary gland of the platyfish, Xiphophorus maculatus, at different ages and stages of development from birth to sexual maturity. Immunoreactive neuropeptide Y was found in perikarya and tracts of the nucleus olfactoretinalis, telencephalon, ventral tegmentum and in the neurohypophysis and in the three regions of the adenohypophysis. Immunoreactive dynorphin was found in nerve tracts in the olfactory bulb and in cells of the pars intermedia and the rostral pars distalis of the pituitary gland.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 1149-1170 
    ISSN: 0029-5981
    Schlagwort(e): material design ; structural optimization ; multiple loads ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An extension of recent work1 on the simultaneous optimization of material and structure to address the design of structures under multiple loading conditions is presented. Material properties are represented in the most general form possible, namely, as elements of the unrestricted set of positive-semi-definite constitutive tensors of a linearly elastic continuum. Existence of solutions can be shown when the objective is a weighted average of compliances and a resource constraint measured as the 2-norm or the trace of the constitutive tensors is included. The optimized material properties can be derived analytically. The optimization of the layout of the material leads to a sizing problem of structural optimization involving a non-linear, non-smooth elasticity analysis. The computational solution of this problem is discussed and illustrated with examples.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 3483-3495 
    ISSN: 0029-5981
    Schlagwort(e): discretized Green's functions ; multiple scattering ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Discretization of boundary integral equations leads to large full systems of algebraic equations, in practice. Partitioning is a method for solving such systems by breaking them down into smaller systems. It may be viewed merely as a technique from linear algebra. However, it is profitable to view it as arising directly from partitions of the boundary; these partitions could be natural (such as two separate boundaries) but they need not be. We investigate partitioning in the context of multiple scattering of acoustic waves by two sound-hard obstacles (the ideas extend to other physical situations). Specifically, we make a connection between partitioning and the use of the exact Green's function for a single obstacle in isolation. This suggests computing the action of this Green's function once-and-for-all, storing it (perhaps on a compact disc), and then using it to solve other problems in which the second obstacle is altered. One example of this approach is computing the stress distribution around a cavity of a standard-but-complicated shape inside a structure whose shape is varied. The theoretical foundation for these ideas is given, as well as a connection with the use of generalized Born series for multiple-scattering problems. Important distinctions between the partitioning/Green's function idea in this paper and seemingly similar ideas such as substructuring, multi-zoning, and domain decomposition are made.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 687-704 
    ISSN: 0029-5981
    Schlagwort(e): boundary element methods ; Cauchy principal-value integrals ; Hadamard finite-part integrals ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Hypersingular integrals are guaranteed to exist at a point x only if the density function f in the integrand satisfies certain conditions in a neighbourhood of x. It is well known that a sufficient condition is that f has a Hölder-continuous first derivative. This is a stringent condition, especially when it is incorporated into boundary-element methods for solving hypersingular integral equations. This paper is concerned with finding weaker conditions for the existence of one-dimensional Hadamard finite-part integrals: it is shown that it is sufficient for the even part of f (with respect to x) to have a Hölder-continuous first derivative - the odd part is allowed to be discontinuous. A similar condition is obtained for Cauchy principal-value integrals. These simple results have non-trivial consequences. They are applied to the calculation of the tangential derivative of a single-layer potential and to the normal derivative of a double-layer potential. Particular attention is paid to discontinuous densities and to discontinuous boundary conditions. Also, despite the weaker sufficient conditions, it is reaffirmed that, for hypersingular integral equations, collocation at a point x at the junction between two standard conforming boundary elements is not permissible, theoretically. Various modifications to the definition of finite-part integral are explored.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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