1,720,979 research outputs found
Effects of light and temperature on Mg uptake, growth, and calcification in the proxy climate archive <i>Clathromorphum</i> <i>compactum</i>
No full textThe shallow-marine benthic coralline alga Clathromorphum compactum
is an important annual- to sub-annual-resolution archive of Arctic and
subarctic environmental conditions, allowing reconstructions going back
> 600 years. Both Mg content, in the high-Mg calcitic cell walls,
and annual algal growth increments have been used as a proxy for past
temperatures and sea ice conditions. The process of calcification in
coralline algae has been debated widely, with no definitive conclusion about
the role of light and photosynthesis in growth and calcification. Light
received by algal specimens can vary with latitude, water depth, sea ice
conditions, water turbidity, and shading. Furthermore, field calibration
studies of Clathromorphum sp. have yielded geographically disparate
correlations between MgCO3 and sea surface temperature. The
influence of other environmental controls, such as light, on Mg uptake and
calcification has received little attention. We present results from an
11-month mesocosm experiment in which 123 wild-collected C.
compactum specimens were grown in conditions simulating their natural
habitat. Specimens grown for periods of 1 and 2 months in complete darkness
show that the typical complex of anatomy and cell wall calcification develops
in new tissue without the presence of light, demonstrating that calcification
is metabolically driven and not a side effect of photosynthesis. Also, we
show that both light and temperature significantly affect MgCO3 in
C. compactum cell walls. For specimens grown at low temperature
(2 °C), the effects of light are smaller, with a 1.4 mol %
MgCO3 increase from low-light (mean  =  17 lx) to high-light
conditions (mean  =  450 lx). At higher (10 °C) temperature there
was a 1.8 mol % MgCO3 increase from low to high light. It is
therefore concluded that site- and possibly specimen-specific temperature
calibrations must be applied, to account for effects of light when generating
Clathromorphum-derived temperature calibrations.</p
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
Environmental drivers of calcification in tropical coralline algae
No full textIn this talk, we will provide an overview of the research we are currently undertaking to understand the influence of the environment, particularly ocean acidification, on the growth and calcification of crustose coralline algae (CCA) in the Great Barrier Reef (GBR) and the Caribbean. A first step towards this goal is to understand the mechanisms and patterns of calcification, growth and mineralogical composition. We are making significant progress to unravel the molecular basis of CCA calcification and have now identified RNA molecules (transcriptomes) involved in biomineralization and other key processes (T. Page work). Because biomineralization in the CCA occurs in the cell walls, we are studying the monosaccharide constituents of the cell wall and their potential role in calcification (E. Bergstrom work). Understanding the influence of environmental variability on the calcification process requires fundamental research on species boundaries and phylogeny of the corallines, as well as knowledge of the distribution of species across reef habitats. This knowledge allows us to examine in more detail the influence of water quality, seasonality and upwelling (Caribbean) on CCA calcification and mineralogical composition and to obtain growth and calcification estimates of CCA along the GBR. There is considerable variability in CCA responses to ocean acidification and our recent experiments suggest that this variability may also be explained by their evolutionary history. This work is critical for advancing our understanding of anthropogenic influences on CCA ecology and the critical roles they play in reef ecosystem functioning, in particular their contribution to reef framework construction.No Full Tex
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
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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