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Projected quasi-Newton algorithm with trust region for constrained optimization (1990)

Zhang, J. Z. ; Zhu, D. T.

Springer

Journal of optimization theory and applications 67 (1990), S. 369-393

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ISSN: 1573-2878

Keywords: Two-sided projected Hessians ; trust regions ; differentiable penalty functions ; global convergence ; two-step Q-superlinear rate ; constrained optimization

Source: Springer Online Journal Archives 1860-2000

Topics: Mathematics

Notes: Abstract In Ref. 1, Nocedal and Overton proposed a two-sided projected Hessian updating technique for equality constrained optimization problems. Although local two-step Q-superlinear rate was proved, its global convergence is not assured. In this paper, we suggest a trust-region-type, two-sided, projected quasi-Newton method, which preserves the local two-step superlinear convergence of the original algorithm and also ensures global convergence. The subproblem that we propose is as simple as the one often used when solving unconstrained optimization problems by trust-region strategies and therefore is easy to implement.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00940481

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Acrosome reaction of stallion spermatozoa evaluated with monoclonal antibody and zona-free hamster eggs (1990)

Zhang, J. ; Boyle, M. S. ; Smith, C. A. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Molecular Reproduction and Development 27 (1990), S. 152-158

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ISSN: 1040-452X

Keywords: Stallion spermatozoa ; Acrosome reaction ; Monoclonal antibody ; Zona-free hamster eggs ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.

Additional Material: 6 Ill.