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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

    Selective C3 deficiency due to C3 nephritic factor in an apparently healty girl.

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    Routine laboratory investigations performed on the serum of an 8-year-old girl examined because of a moderate degree of iron-deficiency anemia showed a markedly reduced C3 level. More detailed complement studies revealed a selective C3 deficiency, as indicated by the almost undetectable C3 concentration tested by both hemolytic and immunochemical assays and by the normal or slightly reduced levels of all the other complement components. The hemolytic activity of the serum was restored by the addition of partially purified C3 component. The isolated C3 deficiency could be attributed to the presence of a C3-cleaving activity in the serum of the propositus. This activity was identified as C3 nephritic factor (C3NeF) since it was heat-stable, was absorbed by Cowan I strain ofStaphylococcus aureus and was eluted in the IgG fraction after DEAE-chromatography of the serum. The levels of H and I factors of the alternative pathway in the serum of the propositus and of C3 in the serum samples of her parents and two siblings were found to be within the normal range. The previous clinical history of the girl and the follow-up for a period of approximately 5 years showed that she was apparently healthy and did not reveal clinical and/or laboratory evidence of glomerulonephritis, lipodystrophy or repeated bacterial infections usually associated with the presence of C3NeF in the serum
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