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  • 1
    Digitale Medien
    Digitale Medien
    On the best case performance of hit and run methods for detecting necessary constraints (1992)
    Springer
    Mathematical programming 54 (1992), S. 233-249 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Hit and run methods ; redundancy ; linear inequalities ; coupon collector's problem
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract The hit and run methods are probabilistic algorithms that can be used to detect necessary (nonredundant) constraints in systems of linear constraints. These methods construct random sequences of lines that pass through the feasible region. These lines intersect the boundary of the region at twohit-points, each identifying a necessary constraint. In order to study the statistical performance of such methods it is assumed that the probabilities of hitting particular constraints are the same for every iteration. An indication of the best case performance of these methods can be determined by minimizing, with respect to the hit probabilities, the expected value of the number of iterations required to detect all necessary constraints. We give a set of isolated strong local minimizers and prove that for two, three and four necessary constraints the set of local minimizers is the complete set of global minimizers. We conjecture that this is also the case for any number of necessary constraints. The results in this paper also apply to sampling problems (e.g., balls from an urn) and to the coupon collector's problem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586052
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  • 2
    Digitale Medien
    Digitale Medien
    Tissue specific expression of the Drosophila Adh gene: a comparison of in situ hybridization and immunocytochemistry (1991)
    Springer
    Genetica 84 (1991), S. 95-100 
    Details
    ISSN: 1573-6857
    Schlagwort(e): Drosophila ; alcohol dehydrogenase ; in situ ; immunocytochemistry ; gene regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The tissue specific patterns for Drosophila melanogaster alcohol dehydrogenase (Adh) mRNA and protein expression were determined using in situ hybridization and immunocytochemical techniques. Alcohol dehydrogenase mRNAs were localized in thin sections of frozen tissue using the hybridization of single stranded RNA probes. Alcohol dehydrogenase protein was identified in frozen tissue samples using ADH antisera, a biotinylated secondary antibody, and streptavidin conjugated to horseradish peroxidase. In tissues such as fat body, gastric caeca, and adult cardiac valve, the patterns of expression for ADH protein and mRNA were identical. Other tissues such as oocytes, nurse cells, imaginal disks, and brain show levels of Adh mRNA that are lower than or equivalent to those observed in the previously mentioned tissues, but they exhibit little or no ADH protein. The lack of concordance between Adh mRNA and ADH protein expression in oocytes and nurse cells may reflect the packaging of maternal mRNAs (but not ADH protein) for use in early development. The reason(s) for the other discrepancies in protein and mRNA expression are not known at this time but may be due to post-transcriptional regulation in these specific tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00116548
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