1,721,211 research outputs found
Mistletoebirds vary their dietary intake of arthropods depending on time of year
No full textNapier, K.R.; McWhorter, T.J.; Martinez Del Rio, C.; Fleming, P.A
Autotomy, tail regeneration and jumping ability in Cape dwarf geckos (Lygodactylus capensis) (Gekkonidae)
Full text linkMany studies have examined the effect of caudal autotomy on speed and behaviour of lizards escaping over horizontal surfaces, but there have been few studies on lizards escaping over vertical surfaces and, in particular, species that jump between surfaces. We examined jumping by the Cape dwarf gecko (Lygodactylus capensis) in terms of individuals’ varying states of tail autotomy and regeneration. Although longer jumps were less likely to be successful (i.e. the animal would not successfully grip the surface and fell to the ground), there was no difference in the distance over which animals with full and partial tails would attempt to jump. Both recently autotomised individuals and individuals with intact tails successfully jumped up to nine times their body length (snout-vent length). The jumping ability of L. capensis was therefore clearly not negatively impaired by tail loss, presumably because the geckos are using their hind legs to propel their jump. Their tails may, however, be important to control their landing as well as their locomotion on vertical surfaces. The high observed frequency of tail loss, coupled with rapid and complete regeneration (including the scansorial tail tip), suggests that caudal autotomy is an important survival tactic in this species
Can sugar preferences in Australian birds be explained by behaviour or physiology?
No full textNapier, K.R.; Xie, S.; McWhorter, T.J.; Nicolson, S.W.; Martinez Del Rio, C.; Fleming, P.A
An intra- and interspecific study of body size and autotomy as a defense in Orthoptera
Full text linkAutotomy, the ‘voluntary’ shedding of a limb or other body part, is a highly effective escape mechanism to avoid predation or other forms of entrapment. Autotomy, however, comes with costs to locomotion, reproductive behavior, regeneration etc. It has been suggested that increasing body size and ‘robustness’ may allow for less reliance on this extreme form of predator defense, but this theory has never been tested. Here we present behavioral observations (‘willingness’ or time taken to lose an entrapped limb) of Orthoptera of a range of body size and mass. These data strongly suggest that body size and mass may be an important determinant of the use of autotomy as an escape mechanism within the Order, possibly due to the effects of body size upon the efficacy of autotomy, as well as other defense mechanisms. An ontogenetic study for Gryllus bimaculatus, however, shows no clear trend in willingness to autotomize a limb with body mass, suggesting that this defense tactic may be less affected by body size per se, but rather by the tactics developed by each individual species
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
A comparison of pharmacokinetic methods for in vivo studies of non-mediated glucose absorption
No full textNapier, K.R.; McWhorter, T.J.; Martinez Del Rio, C.; Fleming, P.A
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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