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  • 1
    Digitale Medien
    Digitale Medien
    On scheduling variable length broadcasts in wireless networks (1997)
    Springer
    Telecommunication systems 8 (1997), S. 211-227 
    Details
    ISSN: 1572-9451
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper the problem of generating a schedule for a given set of broadcasts in a Packet Radio Network is considered. The schedule must be free from primary and secondary interference. Both fixed and variable frame length cases are investigated. We show that this problem is NP‐complete even in its decision version. We also present several fast suboptimal centralized and distributed heuristics, as well as their average performances obtained through computer simulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019113521414
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Structure and expression of duplicate AGAMOUS orthologues in poplar (2000)
    Springer
    Plant molecular biology 44 (2000), S. 619-634 
    Details
    ISSN: 1573-5028
    Schlagwort(e): AGAMOUS ; cottonwoods ; dioecy ; floral development ; MADS-box ; Populus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To investigate the homeotic systems underlying floral development in a dioecious tree, and to provide tools for the manipulation of floral development, we have isolated two Populus trichocarpa genes, PTAG1 and PTAG2, homologous to the Arabidopsis floral homeotic gene AGAMOUS (AG). PTAG1 and PTAG2 are located on separate linkage groups, but their non-coding regions are highly similar, consistent with a phylogenetically recent duplication. Intron/exon structure is conserved in relation to AG and the Antirrhinum AG orthologue, PLENA (PLE), and low-stringency Southern analysis demonstrated the absence of additional genes in the poplar genome with significant PTAG1/2 homology. PTAG1 and PTAG2 exhibit an AG-like floral expression pattern, and phylogenetic analysis of the AG subfamily strongly supports evolutionary orthology to C-class organ identity genes. The high degree of similarity shared by PTAG1 and PTAG2 in both sequence (89% amino acid identity) and expression indicates that they are unlikely to be functionally associated with specification of tree gender. Unexpectedly, PTAG transcripts were consistently detected in vegetative tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026550205851
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    Artikel (Nationallizenzen)
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  • 3
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    Smoothening Helps: A Probabilistic Analysis of the Multi-Level Feedback Algorithm (2003)
    Details
    Publikationsdatum: 2014-02-26
    Beschreibung: In this paper we introduce the notion of smoothed competitive analysis of online algorithms. Smoothed analysis has been proposed by [{\sl Spielman and Teng} STOC 2001] to explain the behaviour of algorithms that work well in practice while performing very poorly from a worst case analysis point of view. We apply this notion to analyze the Multi-Level Feedback (MLF) algorithm to minimize the total flow time on a sequence of jobs released over time when the processing time of a job is only known at time of completion. The initial processing times are integers in the range $[1,2^K]$. We use a partial bit randomization model, where the initial processing times are smoothened by changing the $k$ least significant bits under a quite general class of probability distributions. We show that MLF admits a smoothed competitive ratio of $O(max((2^k/\sigma)^3, (2^k/\sigma)^2 2^K-k))$, where $\sigma$ denotes the standard deviation of the distribution. In particular, we obtain a competitive ratio of $O(2^K-k)$ if $\sigma = \Theta(2^k)$. %The analysis holds for an oblivious as well as for a stronger adaptive %adversary. We also prove an $\Omega(2^{K-k})$ lower bound for any deterministic algorithm that is run on processing times smoothened according to the partial bit randomization model. For various other smoothening models, including the additive symmetric smoothening model used by [{\sl Spielman and Teng}], we give a higher lower bound of $\Omega(2^K)$. A direct consequence of our result is also the first average case analysis of MLF. We show a constant expected ratio of the total flow time of MLF to the optimum under several distributions including the uniform distribution.
    Schlagwort(e): ddc:000
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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