1,721,056 research outputs found
Influence of elevation on the species–area relationship
Full text linkAim: Species–area relationships (SARs) are among the best investigated patterns in ecology, yet the shape of the function that should describe SARs and the biological meaning of the function parameters are disputed. Elevational gradients offer the opportunity of investigating how biodiversity responds to large variations in environmental characteristics within small geographical areas. We asked which function describes SARs at different elevations and explored how variations in environmental characteristics influence SAR shape. Location: Alborz Mountains (Iran). Taxon: Vascular plants. Methods: We used sets of nested plots (0.001 to 100 m2) placed at 100 m intervals from 2,000 to 4,500 m elevation to construct series of nested SARs as species accumulation curves. Then, we used these curves to assess the appropriateness of different SAR functions at different elevations. We investigated how parameters of the power function varied along the elevational gradient in response to variation in environmental parameters (ruggedness, temperature, precipitation, exposed rock, percentages of soil sand and total nitrogen, and productivity, expressed by the normalized difference vegetation index). Results: The most frequently observed best fit model was the power function, which is controlled by two parameters: z (the velocity in species accumulation with sampled area) and c (the species richness per unit area). z was positively influenced by temperature and soil nitrogen, decreasing with elevation. c was positively influenced by temperature and soil nitrogen, and negatively by rock cover, decreasing with elevation. Main conclusions: The decrease in c-values with elevation is consistent with the altitudinal decrease in species richness and is explained by the increase in bare rock. By contrast, c was positively influenced by temperature and total nitrogen, which are two factors promoting plant growth. Similarly, z-values decreased with elevation, thus indicating a decrease in beta diversity
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
Remote meta-selective C-H bromination of arenes using a recyclable Ru-based aminopropyl bifunctional PMO with robust imidazolium bridges
No full textThis systematic study delves into the synthesis and characterization of robust bi-functional aminopropyl-tagged periodic mesoporous organosilica with a high loading of small imidazolium bridges in its framework (PrNH2@R-PMO-IL, ∼2 mmol g−1 of IL). The materials proved to be a reliable and enduring support for the immobilization of Ru species, demonstrating strong performance and excellent selectivity in the meta-bromination of various derivatives of 2-phenylpyridine compounds and other heterocycles, showcasing its effectiveness and robust nature. The synthesized materials were thoroughly characterized to determine their structural properties, such as pore size distribution, loading of organic groups, and surface area, using various analytical techniques. The research aims to improve the catalytic activity of supported ruthenium species in meta-selective bromination reactions through a systematic approach that emphasizes the synergistic effects of the mesoporous structure, concentration of imidazolium incorporated, and aminopropyl functionalization for enhancing the catalytic performance of the supported Ru species in these reactions. Our findings indicate that the developed catalyst system exhibits promise as a recyclable catalyst for meta-C-H activation, offering the potential for multiple reaction cycles and reduced waste production. This study highlights the enhanced catalytic performance and versatility of Ru@PrNH2@R-PMO-IL in comparison with previously documented homogeneous and heterogeneous catalyst systems, even when using lower loading levels. This is particularly evident in meta-C-H bromination of challenging substrates, such as 1-phenylpyrazole for the first time under the described catalytic chemical reaction
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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