1,720,976 research outputs found
Stable isotopes (C, N, O, H) of feathers collected in an Italian alpine region, during postbreeding migration
Get PDFOver the last 20 years the analysis of stable isotope ratios of carbon, nitrogen, oxygen, hydrogen and sulphur have gradually become a formidable tool for the animal ecologists (Hobson and Wassenaar, 1997; Marra et al., 1998; Inger and Bearhop, 2008). In particular many studies have been developed on tracking the movement and the diet of birds in time and space, fundamental to understanding their ecology, but also inherently difficult to determine.
The aim of this study was to deepen the origin and behaviour of migratory bird species crossing the Trentino area, an Italian alpine region, during the post-nuptial migration period, and monitored by a long term study by ringing activities (Progetto Alpi, Pedrini et al. 2008).
About 800 samples of feathers from 48 local bird species were collected during 2010 – 2012 years. Analysis of d13C, d15N, d18O and dD were performed on these samples using an Isotope Ratio Mass Spectrometer (IRMS) interfaced with an Elemental Analyser or a pyrolyser after a pre-treatment of the feathers (cleaning with diethyl ether:methanol 2:1, equilibration to ambient humitity for 4 days and, for d18O and dD a final drying step wth P2O5 for another 4 days).
A first survey of the obtained data is presented in this work. As expected, the first statistical elaboration/’look’ of them confirmed that 13C can be used to trace the importance of different carbon pools to a consumer (e.g. C3, C4 or CAM plants, marine algae) whereas d15N vary as a function of a variety of biological, geochemical and anthropogenic processes and is a very effective tracer of trophic level. In particular, it was interesting to note that the specie Loxia curvirostra showed particularly high d13C and low d15N values probably due to the eating of conifer seeds and whereas the specie Motacilla flava, that bases its diet primarily on worms and insects, presented high d15N values. On the other hand d18O values mainly depends by geographical/diet factors whereas dD values are strongly affected by the geographical characteristics of the regions in which the birds grown or emigrated. The specie Troglodytes troglodytes, which is mainly sedentary, showed the higher dD values, whereas Carduelis spinus, which during autumn migrates from the north of Europe to the Mediterranean area, presented the lower values. As regards d18O, interesting was the very high values presented by Anthus pratensis specie.
Further elaborations/studies by adopting a multi-isotope approach could surely increase the resolution of migratory origins
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
The use of stable isotopes (C,N,O,H) in the study of the postbreeding migration across the Alps
No full textIn animals the stable isotope ratios of bioelements such as carbon, nitrogen and hydrogen reflect those in the diet and drinking water, which in turn mostly depend on climatic, hydrological or geographical conditions, all this being due to isotopic fractionation occurring during physical and chemical processes and along metabolic pathways. For this reason, over the last 25 years analysis of stable isotope ratios has gradually become a formidable tool for animal ecologists. In particular, many studies have been carried out to track the movement and diet of birds over time and space, aspects fundamental for understanding their ecology, but also inherently difficult to determine.
The aim of this study was to extend knowledge of the origin and behaviour of migratory bird species crossing the Trentino area, an Italian alpine region, during the post-nuptial migration period, species monitored using ringing activities in a long term study within the Alpi project.
About 800 samples of feathers from 48 species were collected during the period 2010 – 2011 at Bocca di Caset ringing station (1605 msm). Analysis of d13C, d15N and d2H was performed on these samples using an Isotope Ratio Mass Spectrometer (IRMS) interfaced with an Elemental Analyser or pyrolyser, after pre-treatment of the feathers (cleaning with diethyl ether : methanol 2:1, equilibration to ambient humidity for 4 days).
An initial survey of the data obtained is here presented. As expected, preliminary results confirmed that 13C can be used to trace the importance of different carbon pools in the foods consumed (e.g. C3, C4 or CAM plants, marine algae), whereas d15N varied on the basis of a variety of biological, geochemical and anthropogenic processes and is very effective in tracing trophic level. In particular species whose diet is based primarily on invertebrates (e.g. Motacilla flava), had the highest d15N values, whereas totally granivorous species (Carduelis spinus, Coccothraustes coccothraustes) showed the lowest values. Interestingly Loxia curvirostra showed particularly high d13C and low d15N values, probably due to the eating of conifer seeds. On the other hand, d2H values are strongly affected by the geographical characteristics of the regions in which the birds grew up. Species of central-European origin such as Troglodytes troglodytes showed the higher d2H values, whereas species that originate mainly from north-eastern Europe (e.g. Carduelis spinus, Fringilla montifringilla) showed the lower values. However, the range of values in some species (e.g. Delichon urbicum, Carduelis spinus, Fringilla montifringilla, Erithacus rubecula) was rather wide, probably due to a higher heterogeneity in their areas of origin.
The results are in agreement with the gained knowledge as regards both diet and possible origin of migratory birds in transit on the Alps and suggest that further elaborations with a multi-isotope approach might increase knowledge as regards migratory origin
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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