1,721,124 research outputs found
Total organic nutrients in Drake Passage
No full textApproximately 400 paired measurements of total organic nitrogen (TON) and total organic phosphorus (TOP) were made on a hydrographic transect across Drake Passage by a uv photooxidation technique. Latitudinal variations in TON and TOP concentrations were observed, with the continental margins having surface-water concentrations approximately 50% greater than those in the centre of Drake Passage. This may be due to enhanced primary production on the continental shelves leading to increased production of organic nutrients. The vertical distributions of TON and TOP were characterised by surface maxima, declining to approximately constant levels of about 2.5 ?M TON and levels of TOP below detection by about 800 m. TON and TOP can be related by the equation TON=(15.7±1.7)TOP+(2.48±0.17), r2=0.44, n=397. This is interpreted as reflecting two weakly connected pools of organic material, the first a substantial refractory pool containing about 2.5 ?M TON and undetectable levels of TOP, which dominates in deep water, and the second a surface labile pool containing TON and TOP in quasi-Redfield stoichiometry. This relationship between TON and TOP is not significantly different from a similar regression of data from the HOTS site in the central Pacific, implying that the composition of organic material, and hence the processes controlling its formation, are not substantially different in these two biogeochemically very different environments. Our postulation of two different pools of organic material with different chemical compositions and residence times leads us to suggest that the cycles of TON and TOP are more strongly coupled than is often thought
Nutrients and chlorophyll at two sites in the Thames plume and southern North Sea
No full textThe Thames plume is a moderately turbid (suspended load up to 80 mg dm?3), high nutrient (summer NO3? concentrations >10 M, summer PO43? concentrations >2.5 M) and well-mixed aquatic ecosystem which connects the Thames estuary to the southern North Sea. Six cruises were undertaken to investigate the response of an inshore site in this system to these high nutrient levels via a comparison with a site in the seasonally nutrient-depleted southern North Sea. The seasonal cycle of chlorophyll concentrations in both environments was similar, consisting of higher chlorophyll a levels in spring than in summer. A spring bloom of diatoms occurs in both environments; in the plume it is succeeded by low chlorophyll levels and a diatom-dominated community at low silicate levels and at the offshore site by a non-siliceous community at similar silicate levels. The low summer chlorophyll levels and diatom dominance, which occur at the inshore site despite an abundance of nitrate and phosphate may be due to a simultaneous inhibition of non-siliceous growth and silicate limitation of diatom growth. We hypothesise that this is caused by the high turbidity at the inshore site reducing water column light levels such that they become adequate for diatom growth but inadequate for non-siliceous growth; however, we have inadequate data to confirm this suggestion. The benthic silicate flux cannot support the inferred diatom silicate requirement at the inshore site suggesting that silicate mineralisation in the water column may occur and control diatom growth. Nutrient/salinity plots suggest that the net effect of this complex biogeochemistry is a semi-conservative transport of NO3? and PO43? through the plume to the offshore region
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
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