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Notes on the freshwater ostracods (Arthropoda: Crustacea) and on the Quaternary deposits of Socotra.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Late Holocene palaeoenvironmental evolution of the Roman harbour of Portus, Italy
No full textWe used two sediment cores from the ancient harbour of Rome (Italy) for palaeoenvironmental reconstruction. The imperial harbour of Rome and its town, Portus, were constructed in the Tiber Delta area. Today, they are similar to 3 km from the coast, close to Leonardo da Vinci International Airport. The port was excavated during the reign of Emperor Claudius, inaugurated by Nero in 64 AD, and substantially enlarged under Emperor Trajan. This paper focuses on analyses of ostracods in sediment cores from the harbour and provides insights into the palaeoenvironmental evolution of the harbour water bodies. Pollen data complement this ostracod-based reconstruction, providing information about the vegetation around the port. One core (PTS13) was taken from the dock area (darsena) excavated at the time of Claudius. The second core (PTS5) was collected from the Trasverso Channel (Canale Trasverso), excavated after the port inauguration and later dredged during the fourth century AD because it had filled in with silt. Radiocarbon, archaeological and pollen data indicate the two cores overlap in time slightly, or perhaps not at all, the core from the dock site (PTS13) containing the older record. Ostracods recovered from the two sites represent very different aquatic environments, driven in one case by the Tiber River input and in the other by "marine" harbour waters. Parallel study of ostracods and pollen in the cores reveals the impact of harbour management activities, which are linked to ship hull maintenance, as well as erosion and siltation in this coastal setting
The Ilyocypris puzzle: A multidisciplinary approach to the study of phenotypic variability
No full textIlyocypris Brady and Norman (1889) is a widespread freshwater ostracod genus including about 30 living and 190 fossil species. The specific identification of the living Ilyocypris relies mainly on the appendages. An identification exclusively based on valves is rather complicated because of a high intraspecific variability of their characters in several species. This study aims to test the taxonomic significance of the valves characters through the examination of specimens unambiguously identified on the basis of their soft part morphology, in order to provide useful taxonomic criteria for the identification of Ilyocypris shells in fossil assemblages. Sixty-five ilyocypridid specimens collected in mainland Italy and surrounding islands were analyzed. The patterns of valve surface ornamentation and of marginal ripplets were examined by electron microscopy.Moreover, the geometricmorphometric analysis of the valve outlineswas performed. Sixty-two specimens could be easily accommodated in eight Ilyocypris species (I. bradyi, I. decipiens, I. getica, I. gibba, I. hartmanni, I. inermis, I. monstrifica, and I. salebrosa) according to the morphology of their appendages. Three additional specimens, with soft parts typical of Ilyocypris but clearly distinct valvemorphology, were left in open nomenclature. Our results show that the outline analysis is often a valid tool to discriminate between different species. Conversely, valve ornamentation displays different degrees of intraspecific variability in some Ilyocypris species. The marginal ripplets are constant within each species population, but they do not always mirror the patterns reported by other authors; therefore, we do not consider them as reliable diagnostic character for specific determination. This study confirms that the identification of Ilyocypris species requires accurate description of appendages as well as external and internal carapace characteristics, and stresses the advantage of a combined neontological and paleontological investigation in solving taxonomic problems related to non-marine ostracods
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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