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First evidence of underwater sounds emitted by the living fossils lepidurus lubbocki and triops cancriformis (Branchiopoda: Notostraca)
Full text linkSound is the most effective means of communication in marine and freshwater eco-systems. However, no data about acoustic emissions from non-malacostracan crustaceans are cur-rently available, so their ability to produce sounds is unknown. For the first time, this study inves-tigated the sound produced by 2 tadpole shrimp species, Triops cancriformis and Lepidurus lubbocki. L. lubbocki individuals were collected from a natural temporary pond in Sicily (Italy), whereas T. cancriformis individuals were obtained from eggs contained in sediment from a rock pool in Sardinia (Italy). In the laboratory, experimental tanks with the animals (one species at a time) were acoustically monitored. Both species produced high-frequency, wideband pulses dis-tinguishable by their sound pressure level, which was higher in L. lubbocki (146 dB) than in T. cancriformis (130 dB), and by their first and second peak frequencies, which were higher in L. lub-bocki (65 and 86 kHz) than in T. cancriformis (63 and 71 kHz). The energy distributions in the power density spectra showed different shapes, as revealed by the 3 dB bandwidth and centre fre-quency. The pulse durations were 88 and 97 μs in L. lubbocki and T. cancriformis, respectively. L. lubbocki presented a higher emission rate than T. cancriformis and a marked circadian pattern, with a higher abundance of sounds during the night. This study reports the first evidence of sound emissions from non-malacostracan crustaceans and reveals the high potential of passive acoustic monitoring to detect the presence, abundance, and life cycle of these elusive keystone species of temporary water bodies
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
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
Fatty Acids Profile as a Tool for Traceability of Bluefin Tuna (Thunnus thynnus) Canned Products
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