1,720,977 research outputs found
A satellite perspective on global blooms of coccolithophores
No full textCoccolithophores are a unique group of phytoplankton that produce calcium carbonate coccoliths. The production of coccoliths can potentially reduce the carbon sink effect associated with phytoplankton photosynthesis. However, this may be offset by a coccolith ‘ballast’ effect that increases particulate organic carbon export efficiency. During a coccolithophore bloom, large quantities of coccoliths are shed into the water column. The unique light scattering properties of calcium carbonate particles of ~2 ?m in size (the size of an Emiliania huxleyi coccolith) have previously been used to develop an algorithm that enables estimates of particulate inorganic carbon (PIC) concentration to be made from space. Here, these satellite derived PIC data have been used to generate a unique set of phonological characteristics, such as start date, peak date and bloom magnitude, for global coccolithophore blooms. A comparison of similar timings generated from chlorophyll data indicates that, contrary to conventional thinking, blooms of coccolithophores can co-?occur with other phytoplankton taxa. An assessment of the environmental conditions associated with coccolithophore blooms suggests that current understanding of coccolithophore bloom characteristics may be associated with the peak of the bloom and that conditions at the start of the bloom can be significantly different (i.e. deep mixed layers, moderate light levels and elevated silicic acid concentrations). A global PIC inventory of 29.0 ± 4.3 MT C was determined from satellite derived PIC and mixed layer depth data. The Great Calcite Belt and tropical Pacific were found to be regions that make a significant contribution to this budget. The data produced in this thesis provide the first multi-?year, global overview of coccolithophores and offer a novel means of monitoring coccolithophore populations over the long-term, global scales needed to identify the possible influences of climate change
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
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
Regional characteristics of the temporal variability in the global particulate inorganic carbon inventory
No full textCoccolithophores are a biogeochemically important calcifying group of phytoplankton that exert significant influence on the global carbon cycle. They can modulate the air‐sea flux of CO2 through the processes of photosynthesis and calcification and, as one of the primary contributors to the oceanic particulate inorganic carbon (PIC) pool, promote the export of organic carbon to depth. Here we present the first interannually resolved, global analysis of PIC standing stock. Average, global PIC standing stock in the top 100 m is estimated to be 27.04 ± 4.33 Tg PIC, with turnover times of ~7 days, which suggests PIC is likely removed by active processes such as grazing or rapid sinking, mediated through biogenic packaging (i.e., fecal pellets). We find that the Southern Hemisphere plays a significant role in the variability in PIC inventories and that interannual variability in PIC standing stock is driven primarily by variability in the midlatitude oceanic gyres and regions within the Great Calcite Belt of the Southern Ocean. Our results provide a framework against which future changes in global PIC standing stocks may be assessed
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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