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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pattern analysis and applications 1 (1998), S. 79-90 
    ISSN: 1433-755X
    Keywords: Cluster analysis ; K-means ; Monte Carlo ; Moving method ; Unsupervised learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In recent years there has been increasing interest in the comparative clustering abilities of k-means, moving methods and self-organising neural networks. However, most comparative studies have either been restricted to specific problem areas or have been conducted with other limitations that do not provide a more general evaluation of the relative abilities of these methods under a wide variety of conditions. This report provides a systematic empirical evaluation of the clustering abilities of k-means, moving methods and two commonly used self-organising neural network architectures. Monte Carlo simulation examining the effects of cluster shape, dimensionality, noise, dispersion and number of clusters in the data is used to evaluate the above methods. Results indicate that, on average, k-means, moving methods and ‘winner take all’ self-organising networks perform equally well in terms of clustering ability. However, as the moving method consistently converges faster than k-means, under circumstances where convergence speed is an important factor it may well represent a more appropriate benchmark for future comparisons between pattern partitioning methods.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2016-07-22
    Description: Lungfish first appeared in the geological record over 410 million years ago and are the closest living group of fish to the tetrapods. Palaeoneurological investigations into the group show that unlike numerous other fishes—but more similar to those in tetrapods—lungfish appear to have had a close fit between the brain and the cranial cavity that housed it. As such, researchers can use the endocast of fossil taxa (an internal cast of the cranial cavity) both as a source of morphological data but also to aid in developing functional and phylogenetic implications about the group. Using fossil endocast data from a three-dimensional-preserved Late Devonian lungfish from the Gogo Formation, Rhinodipterus , and the brain-neurocranial relationship in the extant Australian lungfish, Neoceratodus , we herein present the first virtually reconstructed brain of a fossil lungfish. Computed tomographic data and a newly developed ‘brain-warping’ method are used in conjunction with our own distance map software tool to both analyse and present the data. The brain reconstruction is adequate, but we envisage that its accuracy and wider application in other taxonomic groups will grow with increasing availability of tomographic datasets.
    Keywords: neuroscience, palaeontology, evolution
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 3
    Publication Date: 2018-06-21
    Description: Acid-prepared specimens of the placoderm Brindabellaspis stensioi (Early Devonian of New South Wales, Australia) revealed placoderm endocranial anatomy in unprecedented detail. Brindabellaspis has become a key taxon in discussions of early gnathostome phylogeny, and the question of placoderm monophyly versus paraphyly. The anterior orientation of the facial nerve and related hyoid arch structures in this taxon resemble fossil osteostracans (jawless vertebrates) rather than other early gnathostomes. New specimens of Brindabellaspis now reveal the previously unknown anterior region of the skull, including an exceptionally elongate premedian bone forming a long rostrum, supported by a thin extension of the postethmo-occipital unit of the braincase. Lateral overlap surfaces indicate an unusual anterior position for the jaws. Digital rendering of a synchrotron radiation scan reveals a uniquely specialized ethmoid commissure sensory canal, doubled back and fused into a midline canal. The visceral surface of the premedian bone has a plexus of perichondral bone canals. An updated skull roof reconstruction of Brindabellaspis adds to the highly variable dermal skull patterns of the probably non-monophyletic ‘acanthothoracids'. The unusual morphology revealed by the new specimens suggests that the earliest known reef fish fauna contained a diverse range of fishes with specialized ecological roles.
    Keywords: palaeontology
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 4
    Publication Date: 1998-06-01
    Print ISSN: 1433-7541
    Electronic ISSN: 1433-755X
    Topics: Computer Science
    Published by Springer
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  • 5
    Publication Date: 2001-11-01
    Print ISSN: 1433-7541
    Electronic ISSN: 1433-755X
    Topics: Computer Science
    Published by Springer
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