1,720,988 research outputs found
Linking soil microbial communities to vascular plant abundance along a climate gradient
No full textThe ongoing expansion of shrub cover in response to climate change represents a unique opportunity to explore the link between soil microbial communities and vegetation changes. This link is particularly important in peatlands where shrub expansion is expected to feed back negatively on the carbon sink capacity of these ecosystems.
Microbial community structure and function were measured seasonally in four peatlands located along an altitude gradient representing a natural gradient of climate and associated vascular plant abundance.
We show that increased soil temperature and reduced water content are associated with greater vascular plant biomass, in particular that of ericoids, and that this, in turn, is correlated with greater microbial biomass. More specifically, microbial community structure is characterized by an increasing dominance of fungi over bacteria with improved soil oxygenation. We also found that the carbon and nitrogen stoichiometry of microbial biomass differs in relation to soil microbial community structure and that this is ultimately associated with a different investment in extracellular enzymatic activity.
Our findings highlight the fact that the determination of the structural identity of microbial communities can help to explain the biogeochemical dynamics of organic matter and provide a better understanding of ecosystem response to environmental changes
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
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
Effects of elevated CO2 and mineral nitrogen deposition on growth, allocation and decomposition of Sphagnum fallax, Polytrichum strictum and Eriophorum vaginatum in a Sphagnum bog.
No full textAtmospheric CO2-C sequestration is directly related to the formation of peat which in turn is dependent on the production and decomposition of plant material. We studied the various aspects of qualitative and quantitative growth, litter production and decomposition of three characteristic plants found on a Sphagnum bog, produced and decomposed under treatment conditions. Particular emphasis was placed on distinguishing between the effects of litter quality and environmental conditions on litter decomposition. We endeavoured to do this over three different experiments undertaken during the 1997 growing season. Two separated treatments were applied: 1) atmospheric CO2 experiment: CO2= elevated, 560 ppm CO2; AIR= ambient, 360 ppm CO2 2) mineral nitrogen fertilisation experiment: N+=30; N0=0 [kg NH4NO3/ha/a]. Growth of mosses – Both treatments had a negative effect on the two mosses’ height growth and may cause Polytrichum strictum to outcompete Sphagnum fallax in a long term. The water table effect on growth was significant and accounted for almost half the total variance on the ANOVA. NH4 ++ NO3 - concentrations in the bog’s surface water of the CO2/AIR experimental sub-site were correlated to height growth of Sphagnum fallax. Growth of Eriophorum vaginatum – Elevated CO2 had no effect on the plant’s biomass or the root/shoot ratio, but did produce significant cross effects (treatment x time) on leaf dynamics, such as on the vitality index or the production of young leaves per tiller. N fertilisation did not significantly enhance plant biomass, in spite of a clear positive trend for all plant parts. At final harvest, N fertilisation had enhanced the number of tillers by as much as 38%. The outcome was an increased green leaf pool, which lead a 32% reduction in leaf-turnover. Surprisingly, soluble phenols and lignin were affected in the opposite way, where we observed a differential N fertilisation effect on CBSC content. These disparities could have various origins. Phosphorus was generally reduced under both treatments, and may play an important role in the production of CBSC. Soluble phenols concentrations of living parts may have triggered allelochemical inhibitions. As anticipated, the BP may play an important role in the storage of nutrients and photosynthates. Decomposition – P. strictum grown under elevated CO2 pre-treatment decomposed less than those grown in the control, whereas elevated CO2 treatment did not affect the decomposition of any species’ litter. Eriophorum plants grown under N fertilisation decomposed less than those of the control. This could partly be due to enhanced lignin, soluble phenols initial litter concentrations. Furthermore, S. fallax litter decomposition was enhanced under N fertilisation conditions (treatment). Next to litter qualitative changes, the decomposition “efficiencies” of chemical compounds were also affected by the N fertilisation independently from their initial concentrations. N fertilisation pre-treatment increased the loss of soluble phenols and decreased the bacterial activity (ATP). A significant positive relationship has been found between the soluble phenols and bacterial ATP. The N fertilisation treatment reduced the N immobilisation in Eriophorum and decreased the bacterial ATP among litterbags. We concluded that treatment-induced changes in the decomposition process could occur both in the presence or in the absence of changes in the initial litter quality.ECO
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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