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    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Supersensitivity to morphine after chronic sympathetic denervation in guinea-pig colon.

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    Abstract The possible role of opioid systems in the adaptive changes which follow chronic sympathetic denervation in the guinea-pig colon has been studied by comparing the effects of the opioid agonist morphine in control animals and after chronic sympathetic denervation. Supersensitivity to the inhibitory effects of morphine on the peristaltic reflex was observed after chronic sympathetic denervation, while the potency against acetylcholine release was unmodified. Our results suggest that a modification of the opioid system occurs after sympathetic denervation in the guinea-pig colon. Supersensitivity to endogenous opioids at a site different from that regulating acetylcholine release could account for the counter-regulation of intestinal motility after chronic sympathetic denervation.</jats:p
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