1,720,984 research outputs found
A Coupled O2‐CO2 Model for Joint Estimation of Stream Metabolism, O‐C Stoichiometry, and Inorganic Carbon Fluxes
Get PDFWe determine where stream carbon dioxide (CO2) comes from by developing a model for the joint estimation of stream metabolism, oxygen-carbon (O-C) stoichiometry, and fluxes of dissolved inorganic carbon (DIC), based on observations of stream oxygen (O2) and CO2 concentrations. The model is based on a stream reach mass balance of O2, DIC, and total alkalinity, and it accounts for the carbonate system and the contribution of lateral flow. O2 and DIC mass balances are coupled through stoichiometric coefficients for photosynthesis and combined autotrophic and heterotrophic respiration. Under the assumption of constant alkalinity and circumneutral pH, the model simplifies and includes 8 parameters, which are estimated through a Bayesian hierarchical framework. The model accurately reproduced time series of O2 and Co2 from three diverse sites across size and carbonate chemistry gradients. Results allow partitioning of the stream DIC budget, and thus the source of stream CO2 outgassing, into internal (in-stream net ecosystem production) and external (lateral input of terrestrial DIC and atmospheric input) contributions. We observed that the estimated stoichiometric coefficients were typically different from 1—contrary to typical assumptions—leading to divergent estimates of stream CO2 sources depending on the measurement (i.e., O2 vs. C). Parameter posterior distributions revealed the source of parameter uncertainty and the equifinality of some processes in reproducing stream CO2 dynamics, suggesting targeted variables to further investigate in order to better constrain stream C balance. The proposed model is a useful tool for incorporating the rapidly growing stream CO2 data sets into our understanding of terrestrial-aquatic C linkages
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
Inorganic carbon dynamics and their relation to autotrophic community regime shift over three decades in a large, alkaline river
No full textHow much of the excess CO2 in running waters comes from in-stream respiration of organic carbon? To answer this, we developed a 30-yr metabolism-carbonate system database at an hourly resolution for the Loire River, France, a large, alkaline river. We asked the following questions: what are the intra-annual patterns of in-stream (“internal”) CO2 production, what processes drive these patterns, and how do these patterns depend on autotrophic community composition? We estimated internal CO2 production as the ratio of net ecosystem production to CO2 water-to-air flux (FCO2). We also estimated the daily ecosystem quotient (EQ, O2 released: dissolved inorganic carbon [DIC] consumed) and the prevalence of non-CO2 autotrophic DIC uptake pathways under CO2 depletion. Median internal CO2 production was 49% of FCO2 in the Loire from 1990 to 2022. The river predictably shifted from a heterotrophic, CO2 source to an autotrophic, CO2 sink as a function of discharge, leading to four trophic-flux (“trophlux”) states: autotrophic-sink, autotrophic-source, heterotrophic-sink, and heterotrophic-source. During autotrophic states (41% of the time), CO2 depletion (FCO2 ≤ 0, median pCO2 = 135 μatm) led to the use of (Formula presented.) and of CO2 released by CaCO3 precipitation as alternative DIC sources to autotrophs to support their high rates of primary production (occurring on average for 33% of the growing season). Finally, during a period of phytoplankton dominance, the median EQ was 1.3, which was reduced to 1.0 under macrophyte dominance. This work describes a dynamic coupling among autotrophic communities, calcium carbonate equilibria, and discharge-controlled FCO2 that together imply lower-than-predicted FCO2 magnitude and greater-than-predicted internal CO2 production for the Loire River
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
- …
