179 research outputs found

    Theory of ω-languages. II: A study of various models of ω-type generation and recognition

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    ω-languages are sets consisting of ω-length strings; ω-automata are recognition devicesfor ω-languages. In a previous paper the basic notions of ω-grammars, ω-context-free languages (ω-CFL's), and ω-pushdown automata (ω-PDA's) were first defined and studied. In this paper various modes of ω-type generation are introduced and the effect of certain restrictions on the derivations in ω-grammars is investigated. Several distinct models of recognition in ω-PDA's are considered, giving rise to a hierarchy of subfamilies of the ω-CFL's. The relations among these subfamilies are established and characterizations for each family are derived. Non-leftmost derivations in ω-CFG's are studied and it is shown that leftmost generation in ω-CFG's is strictly more powerful than non-leftmost generation

    Measurement of charged-particle multiplicities in gluon and quark jets in p(p)over-bar collisions at root s=1.8 TeV

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    We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, N-q and N-g, produced at the Fermilab Tevatron in p (p) over bar collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of θ(c)=0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q=E-jetθ(c) varies in the range from 12 to 25 GeV. At Q=19.2 GeV, the ratio of multiplicities r=N-g/N-q is found to be 1.64± 0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations

    Phylogenomic analysis of a 55.1 kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani Species Complex

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    Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. Previously (Geiser et al. 2013; Phytopathology 103:400-408. 2013), the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani Species Complex (FSSC). Subsequently, this concept was challenged by one research group (Lombard et al. 2015 Studies in Mycology 80: 189-245) who proposed dividing Fusarium into seven genera, including the FSSC as the genus Neocosmospora, with subsequent justification based on claims that the Geiser et al. (2013) concept of Fusarium is polyphyletic (Sandoval-Denis et al. 2018; Persoonia 41:109-129). Here we test this claim, and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species recently described as Neocosmospora were recombined in Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural and practical taxonomic option available

    Phylogenomic analysis of a 55.1-kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani species complex.

    No full text
    Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option available
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