1,720,970 research outputs found
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
Mechanisms of Soil Erosion in Subtropical Forests of China - Effects of Biodiversity, Species identity, Tree architecture and Spatial variability on Erosivity
Full text linkSoil erosion is a major threat to ecosystems and agricultural land worldwide. To overcome severe soil loss, aff orestation is used as a common tool. However, the mechanisms of soil erosion in forests are understood rarely up to now. There is still a knowledge gap to what extent biodiversity and tree species identity aff ect soil erosion in early successional forest stands, which tree architectural and leaf traits account for these eff ects and which of these traits are important for the spatial variability of soil erosion.
Therefore, this thesis investigated the influence of tree species richness (as a measure
of biodiversity) and tree species identity on rainfall erosivity (measured as throughfall
kinetic energy; TKE). Furthermore, this thesis concentrated on the spatial variability of
TKE. Importance and influence of five tree architectural and nine leaf traits on these
TKE properties were evaluated. In addition, the influence of leaf litter diversity and soil
meso- and macrofauna on initial soil erosion was investigated. The experiments were
carried out in a young subtropical forest of southern China in the framework of the
BEF-China (Biodiversity and Ecosystem Functioning) project.
Tree species richness eff ects on TKE were found only at the local neighborhood scale
while plot-level e ffects of tree species richness on TKE were not found. This eff ect was
attributed to the young age of the forest plantation. Crown cover, canopy layering or
tree heights have not yet fully developed and thus only e ffects at a local neighborhood
scale can be seen. Neighborhood e ffects on TKE were due to larger crown areas and
taller tree heights in more diverse neighborhoods thus increasing TKE.
TKE was highly species-speci c. TKE below Choerospondias axillaris and Sapindus
saponaria were higher and TKE below Schima superba was lower than the mean TKE
of all other eight species. Species-speci c eff ects of TKE occurred due to diff erences in
tree architecture and leaf traits. By far, leaf habit, leaf area and tree height were most
important in inducing species-speci c TKE diff erences by changing rain drop velocity
and drop size.
Furthermore, TKE was spatially variable. Below the fi rst branch of a tree individual
TKE was lowest due to low rain drop velocities and small drop sizes. In contrast, TKE
was highest in the middle of four tree individuals due to a low interception by a low LAI
resulting in higher throughfall amounts.
In addition, this thesis provides a ranking of abiotic and biotic factors according
to their importance for predicting TKE. Leaf area, leaf area index, throughfall and
tree height were the most important variables. These findings emphasize the interplay
between abiotic factors as well as tree architectural and leaf traits for a successful TKE
prediction.
Considering soil erosion management, the erosive potential of TKE in the experimental
forest plantation can be mitigated by smaller leaf areas than 70 cm2, lower
tree heights than 290 cm, lower crown base heights than 60 cm, smaller leaf area index
than 1, more than 47 branches per tree individual and by using single tree species
neighborhoods.
Initial soil erosion (measured as sediment discharge) was not influenced by leaf litter
diversity, but positively aff ected by the presence of soil meso- and macrofauna. This
faunal eff ect arises mainly from arthropods slackening and processing the soil surface
and only marginally from fauna taking part in the decomposition of leaves leading to less
coverage. Nevertheless, leaf litter coverage highly negatively influenced the occurrence
of initial erosion.
Summarizing, biodiversity eff ects on soil erosion were neither present by investigating
tree species richness at plot-level nor by investigating leaf litter diversity. However, a
positive e ffect on TKE at the local neighborhood indicates that this can change with
a full-grown and dense tree canopy with further succession of the forest. It can be
concluded that in young successional forest stands tree architecture, leaf traits, species
identity and abiotic factors are more important in influencing the erosive potential of
rain than biodiversity
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
The influence of leaf litter diversity and soil fauna on initial soil erosion in subtropical forests
No full textAlthough the protective role of leaf litter cover against soil erosion is known for a long time, little research has been conducted on the processes involved. Moreover, the impact of soil meso- and macrofauna within the litter layer on erosion control is not clear. To investigate how leaf litter cover and diversity as well as meso- and macrofauna influence sediment discharge in subtropical forest ecosystems, a field experiment has been carried out in Southeast China. A full-factorial random design with 96 micro-scale runoff plots and 7 domestic leaf species was established and erosion was triggered by a rainfall simulator. Our results demonstrate that leaf litter cover protects soil from erosion (−82 % sediment discharge on leaf covered plots) by rainfall and this protection is removed as litter decomposes. The protective effect is influenced by the presence or absence of soil meso- and macrofauna. Fauna presence increases soil erosion rates significantly by 58 %, while leaf species diversity shows a non-significant negative trend. We assume that the faunal effect arises from arthropods slackening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Even though the diversity level did not show a significant influence, single leaf species in monocultures show rather different impacts on sediment discharge and thus, erosion control. In our experiment, runoff plots with leaf litter from Machilus thunbergii showed the highest sediment discharge (68.0 g m−2) whereas plots with Cyclobalanopsis glauca showed the smallest rates (7.9 g m−2). Copyright © 2015 John Wiley & Sons, Ltd
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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