1,721,024 research outputs found
The explosive defensive system of paussine and brachinine bombardier beetles (Coleoptera Carabidae): comparative morphology and ultrastructure
No full textThe ground beetle subfamilies Paussinae and Brachininae, have always been of interest to scientists because of their ability to explosively eject a hot (up to 100°C) and irritating quinonoid secretion from pygidial glands, in response to attack by predators. The peculiarity of this defensive system led many scientists to consider "bombardier beetle" as a monophyletic lineage, emphasizing the general similarities in morphology, function and chemical reactions, despite the different ways of ejecting the spray (directing the abdomen in brachinines; using the elytral flange of Coanda in paussines). However, studies concerning fine morphology and ultrastructure of the components of the pygidial defensive systems (reaction chambers, valves, ducts, reservoirs, and glands that secrete H2O2, hydroquinones, catalases and peroxidases) are still lacking (paussines) or incomplete (brachinines). In order to render these issues available to a comparative advanced discussion, we performed a morphological and ultrastructural study of representative species belonging to the genera: Metrius (Metriini), Pachyteles and Goniotropis (Ozaenini), and Paussus (Paussini) for Paussinae; and Brachinus and Pheropsophus (Brachinini) for Brachininae. Samples were examined through optical microscopy (dissections, classical histology), scanning (SEM) and transmission (TEM) electron microscopy, and focused ion beam (FIB) microscopy. The relative parts of the defensive systems for each paussine and brachinine species were described, illustrated and comparatively analyzed. We found significant differences between the two systems at both cellular and microstructural levels. Our preliminary results raise some challenges to the acknowledged hypothesis of evolution of this peculiar defensive system that parallel other evidences on the relationship between paussines and brachinines
Paussus favieri (Coleoptera, Carabidae, Paussinae): un modello di eccezione per lo sviluppo di tecniche microscopiche innovative
No full textDescription and illustration of the discotelic larvae of Pachyteles vignai Deuve, 1999 and P. digiulioi Deuve, 1999 from the Otonga cloud forest (Ecuador) (Coleoptera, Carabidae, Ozaenini)
No full textThe peculiar morphology of the discotelic larvae of three species of Pachyteles (Coleoptera, Carabidae, Paussinae, ozaenini) collected in an Andean cloud forest in Ecuador (otonga nature Reserve, Cotopaxi) is here analyzed. All instars of Pachyteles vignai Deuve, 1999, 2nd and 3rd instars of P. digiulioi Deuve, 1999, and the 3rd instar of another undetermined Pachyteles species are described. A particular emphasis on the illustration of the aberrant larval morphology is given by using both traditional drawing techniques and macro multifocal image acquisition, combined with scanning electron microscopy (SEM) for analyzing the details. The diagnostic characters of these larvae are compared to those of the other known larvae of ozaenin
Reconstituted Biomembranes: Stability Study and Detection of Inserted Ion-Channels
No full textSalford (GB
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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