1,721,117 research outputs found
Determination of prey capture rates in the stony coral Galaxea fascicularis: a critical reconsideration of the clearance rate concept
No full textIn order to determine optimal feeding regimes for captive corals, prey capture by the scleractinian coral Galaxea fascicularis was determined by measuring clearance of prey items from the surrounding water. Colonies of G. fascicularis (sized between 200 and 400 polyps) were incubated in 1300 ml incubation chambers. Nauplii of the brine shrimp Artemia sp. were used as the prey item. A series of incubation experiments was conducted to determine the maximal capture per feeding event and per day. To determine maximal capture per feeding event, total uptake of nauplii after one hour was determined for different prey item availabilities ranging from 50 to 4000 nauplii per polyp. To determine maximal capture per day, the corals were subjected to four repetitive feeding events at three different prey item densities (50, 100 and 150 nauplii per polyp). Alongside these quantitative experiments, it was tested to what extent the feeding response of corals is triggered by chemical cues. One hour after food addition, extract of Artemia nauplii was added to the incubation chambers to test its effect on subsequent prey capture rates. In all experiments, prey capture was expressed as the number of nauplii consumed per coral polyp. Total capture of Artemia nauplii by G. fascicularis after a single feeding event increased linearly up till a prey item availability of 2000 nauplii per polyp. Maximal capture per feeding event was estimated at 1200 nauplii per polyp, which is higher than rates reported in previous studies. It became apparent that at high densities of Artemia nauplii, the clearance rate method does not discriminate between active capture and passive sedimentation. Repetitive feeding with 50 nauplii per polyp resulted in a constant total prey capture per feeding event. At a supply of 100 nauplii per polyp, total capture decreased after the first feeding event, and remained constant during the subsequent feeding events at a level comparable to the lower food availability. However, at a supply of 150 nauplii per polyp, total capture per event was higher throughout the entire four-hour incubation period, which obfuscates an accurate estimation of the maximal daily food uptake. In all incubations, a decrease in capture efficiency was observed within the course of the feeding event. In all repetitive feeding experiments, capture efficiency increased immediately upon addition of a new batch of food. This increase in efficiency was not caused by a priming effect of extract of Artemia. The inconsistencies in the data show that estimates of prey capture based on clearance rates should be interpreted with caution, because this method does not take into account potential dynamics of prey capture and release
Conférences temporaires
No full textDumézil Georges, Virolleaud Charles, Kraus P., Janse M. O., Leroquais Victor. Conférences temporaires. In: École pratique des hautes études, Section des sciences religieuses. Annuaire 1934-1935. 1933. pp. 61-69
Conférences temporaires
No full textVirolleaud Charles, Kraus P., Janse M. O., Kojevnikoff A., Jeanmaire Henri. Conférences temporaires. In: École pratique des hautes études, Section des sciences religieuses. Annuaire 1936-1937. 1935. pp. 81-91
Conférences temporaires
No full textVirolleaud Charles, Kraus P., Janse M. O., Kojevnikoff A., Jeanmaire Henri. Conférences temporaires. In: École pratique des hautes études, Section des sciences religieuses. Annuaire 1936-1937. 1935. pp. 81-91
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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