52 research outputs found

    Selective serotonin reuptake inhibitors versus placebo in patients with major depressive disorder. A systematic review with meta-analysis and Trial Sequential Analysis

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    The functional brain networks that underlie Early Stone Age tool manufacture

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    After 800,000 years of making simple Oldowan tools, early humans began manufacturing Acheulian handaxes around 1.75 million years ago. This advance is hypothesized to reflect an evolutionary change in hominin cognition and language abilities. We used a neuroarchaeology approach to investigate this hypothesis, recording brain activity using functional near-infrared spectroscopy as modern human participants learned to make Oldowan and Acheulian stone tools in either a verbal or nonverbal training context. Here we show that Acheulian tool production requires the integration of visual, auditory and sensorimotor information in the middle and superior temporal cortex, the guidance of visual working memory representations in the ventral precentral gyrus, and higher-order action planning via the supplementary motor area, activating a brain network that is also involved in modern piano playing. The right analogue to Broca’s area—which has linked tool manufacture and language in prior work1,2—was only engaged during verbal training. Acheulian toolmaking, therefore, may have more evolutionary ties to playing Mozart than quoting Shakespeare

    Network reliability as a result of redundant connectivity

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    Thesis (MSc (Logistics)--University of Stellenbosch, 2007.There exists, for any connected graph G, a minimum set of vertices that, when removed, disconnects G. Such a set of vertices is known as a minimum cut-set, the cardinality of which is known as the connectivity number k(G) of G. A connectivity preserving [connectivity reducing, respectively] spanning subgraph G0 ? G may be constructed by removing certain edges of G in such a way that k(G0) = k(G) [k(G0) < k(G), respectively]. The problem of constructing such a connectivity preserving or reducing spanning subgraph of minimum weight is known to be NP–complete. This thesis contains a summary of the most recent results (as in 2006) from a comprehensive survey of literature on topics related to the connectivity of graphs. Secondly, the computational problems of constructing a minimum weight connectivity preserving or connectivity reducing spanning subgraph for a given graph G are considered in this thesis. In particular, three algorithms are developed for constructing such spanning subgraphs. The theoretical basis for each algorithm is established and discussed in detail. The practicality of the algorithms are compared in terms of their worst-case running times as well as their solution qualities. The fastest of these three algorithms has a worst-case running time that compares favourably with the fastest algorithm in the literature. Finally, a computerised decision support system, called Connectivity Algorithms, is developed which is capable of implementing the three algorithms described above for a user-specified input graph

    Mikrogebruikstekens op steenwerktuie : eksperimentele waarnemings en 'n studie van werktuie afkomstig van Boomplaasgrot

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    Tesis (M.A.) -- YUniversiteit van Stellenbosch, 1982.Full text to be digitised and attached to bibliographic record

    Palynology and palaeo-environment of Pleistocene hyaena coprolites from an open-air site at Oyster Bay, Eastern Cape coast, South Africa

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    Hyaena coprolites in a soil horizon at Oyster Bay, Eastern Cape coast, South Africa, were found associated with abundant, early Last Glacial vertebrate faunal remains that were apparently accumulated by brown hyaenas and prehistoric humans. Artefacts of the Howieson's Poort sub-stage of the Middle Stone Age occur in the same soil. Although direct association between the different finds cannot be demonstrated, there is evidence to suggest that they are broadly contemporaneous. Pollen assemblages in the coprolites were dominated by Myrica and, to a lesser extent, Stoebe-Elytropappus type and Poaceae. Comparison with the modern pollen spectrum suggests that the past environment differed markedly from the current. The presence of Stoebe-Elytropappus, in particular, is considered to indicate a displacement of vegetation zones to lower altitudes. Both fossil pollen and fauna suggest a landscape with a complex mosaic of vegetation indicative of overall cooler, more inland conditions than today

    Bedding, hearths, and site maintenance in the Middle Stone Age of Sibudu Cave, KwaZulu-Natal, South Africa

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    Micromorphological analysis of sediments from the Middle Stone Age site of Sibudu Cave, KwaZulu-Natal, South Africa, provides a high-resolution sequence and evidence of site formation processes of predominantly anthropogenic deposits. This methodology allows for a detailed interpretation of individual anthropogenic activities, including the construction of hearths and bedding and the maintenance of occupational surfaces through the sweep out of hearths and the repeated burning of bedding. This analysis also provides a context for evaluating other studies at the site relating to magnetic susceptibility, paleobotany, paleozoology, anthracology, and studies of ochre
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