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  • 1
    Electronic Resource
    Electronic Resource
    Inertia-preserving secant updates (1989)
    Springer
    Journal of optimization theory and applications 62 (1989), S. 1-16 
    Details
    ISSN: 1573-2878
    Keywords: Inertia-preserving updates ; secant updates ; Broyden updates ; optimally conditioned updates ; SR1 update
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A class of rank-two, inertia-preserving updates for symmetric matricesH c is studied. To ensure that inertia is preserved, the updates are chosen to be of the formH +=FH c F t, whereF=I+qr t, withq andr selected so that the secant equation is satisfied. A characterization is given for all such updates. Using a parameterization of this family of updates, the connection between them and the Broyden class of updates is established. Also, parameter selection criteria that can be used to choose the optimally conditioned update or the update closest to the SR1 update are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00939626
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  • 2
    Electronic Resource
    Electronic Resource
    Inertia-preserving secant updates (1991)
    Springer
    Journal of optimization theory and applications 68 (1991), S. 203-203 
    Details
    ISSN: 1573-2878
    Keywords: Inertia-preserving updates ; secant updates ; Broyden updates ; optimally conditioned updates ; SRI update
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Corrections to the last two equations of Ref. 1 are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00939942
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The morphological and ultrastructural appearance of the crater defect in stallion spermatozoa (1985)
    New York, NY : Wiley-Blackwell
    Gamete Research 12 (1985), S. 41-46 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoa ; stallion ; crater defect ; electron microscopy ; nuclear ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The appearance of the nuclear abnormality “crater defect” is described in spermatozoa from the domestic horse (Equadae). Under scanning electron microscopy, the defect appears as a severe depression at any area of the sperm nucleus or as a blister or swelling at some point on the sperm nucleus. Ultrastructurally, the crater appears as a nuclear vacuole containing amorphous material similar to that described in bull and boar sperm. The craters ranged in size from 0.5 to 2 μm in diameter. Within ejaculates of stallions having this defect, the percentages of sperm with crater defects varied widely over time, being as high as 60% and as low as 15%.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120120105
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The crater defect in boar spermatozoa: A correlative study with transmission electron microscopy, scanning electron microscopy, and light microscopy (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 259-266 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoa ; boar ; crater defect ; electron microscopy ; nucleus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Nuclear vacuoles resembling the “crater defect” described in bull spermatozoa were observed in 14 boars. Both the incidence of the defect and semen quality were monitored with phase contrast microscopy over a three-month period. The percentages of cratered spermatozoa varied widely both among boars and in ejaculates from the same boar taken on different days. The presence of cratered spermatozoa at a level of 5% or more appeared to be associated with low semen quality. The defect was studied with scanning and transmission electron microscopy and was found to consist of nuclear invaginations, about 0.5 μm in diameter, containing some scanty amorphous electron-dense material. In boars showing a high incidence of spermatozoa with crater defects, abnormalities of the acrosome and perforatorium were common.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120030308
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  • 5
    Electronic Resource
    Electronic Resource
    Attempted sexing of bovine spermatozoa by fractionation on a Percoll density gradient (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 20 (1988), S. 83-92 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoal ; separation ; flow cytometry ; semen sexing ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine spermatozoa were fractionated on Percoll density gradients into two major subpopulations of motile spermatozoa and a minor fraction containing mostly nonmotile spermatozoa with abnormal morphology. Fractionation required the addition of bovine serum albumin and a continuous Percoll gradient buffered with sodium bicarbonate. It is postulated that, under suitable ionic conditions, the binding of bovine serum albumin to spermatozoa amplifies subtle differences between subpopulations. These studies were directed toward separating Y- and X-bearing spermatozoa. However, when the subpopulations were evaluated by flow cytometry, their Y:X ratios were similar to that of an unfractionated control.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120200108
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    Paper (German National Licenses)
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