1,720,969 research outputs found
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
TREE STORIES ABOUT A PEATLAND: TREE-RING RECONSTRUCTIONS OF WATER TABLE AND LARCH SAWFLY OUTBREAKS IN SASKATCHEWAN
Get PDFEastern larch (Larix laricina) and black spruce (Picea mariana) are the most dominant tree species in peatlands in Canada, however interactions between peatland hydrology and species-specific radial growth are poorly understood. This study investigates the relationships between the growth/hydrological response of eastern larch and black spruce across a topographical gradient within a peatland in Saskatchewan. Tree-ring analysis revealed that peatland hydrology is the main factor driving radial-tree growth. Black spruce on the edge of the fen showed a positive relationship to increased water-table level, while eastern larch in the fen revealed a negative correlation to water-table level rise. Further analysis illustrated that radial-tree growth response to hydrology is dependent on specific water-table levels according to species and micro-site. Identified thresholds indicated that only 8 cm of variability in water-table level can greatly affect the fen forest dynamics. Once the relationship between tree ring and hydrology was established, a multiple- species regression equation was derived from tree-ring data to reconstruct past water-table levels. Results indicated that eastern larch and black spruce are suitable proxies to reconstruct hydrological variability at the site.
Eastern larch ring widths are not only subjected to change by hydrology, but they can also be altered by exposure to larch sawfly outbreaks (Pristiphora erichsonii). Researchers have often been limited in their ability to draw accurate conclusions regarding the history of sawfly outbreaks in peatlands. Water-table level suppressions result in similar radial-growth patterns as when trees are defoliated by larch sawfly, making accurate diagnoses of larch sawfly outbreak a challenge. In this study I investigated the relationship between sawfly outbreaks and peatland hydrology. Five outbreaks where identified using traditional dendroecological analysis. The last outbreak identified was found to be a result of hydrological growth suppression and not sawfly defoliation. Observations indicated that periods of low water-table level may lead to increased populations of larch sawfly in northern Saskatchewan. I stress the necessity of using long-term hydrological analyses to accurately infer outbreak periods to distinguish them from water-table suppression
THE ROLE OF PLANT HYDRODYNAMICS AND PHENOLOGY IN PLANT WATER SOURCE APPORTIONMENT
Get PDFUnderstanding plant water sources, their apportionment in time, and the age distribution of transpired water remains
a major challenge in ecohydrology. While we know that transpiration is a dominant flux in the terrestrial water
cycle, and that precipitation has been increasingly partitioned into evapotranspiration rather than runoff, the understanding
of where trees get their water remains a major research gap. Basic questions of what sources of water are
being taken up by roots, how that water travels through the xylem, how long takes for water to reach the stomata and
then diffuse back to the atmosphere are key to identify mechanisms that control the partitioning of soil water storage
into streamflow and transpiration. Trees use and store significant amounts of water. Their roots can create preferential
flow paths in the soil, redistribute water within the soil profile, and reach far-deep water storages. Yet, the role of
tree hydrodynamics and phenological processes have not been explored in the context of source apportionment age
distribution of transpiration. This challenges our ability to fully understand how forests use, store, and cycle water.
I undertook a high-resolution weighing lysimeter experiment located in Switzerland, and a large field-based investigation
at two long-term studies sites in Canada. In these studies, tree water transport, stem radius change, tree water
status, and phenological transition phases were monitored along with high-temporal resolution measurements of stable
isotopes in trees, soil and precipitation. The goal was to determine the mechanisms that control tree water use in space
and in time and factors that may influence observations of stable isotopes within trees. The major findings of this
research were firstly that xylem water analysis using direct vapor equilibration on laser spectroscopy, results in spectral
contamination introduced by organic compounds. But 17O-excess can be used as a tool to flag and quantify the degree
of spectral contamination in direct vapor analysis and overcome the lack of flagging software or tools to detect contamination
in vapor mode. Second, tree water status drives source water apportionment. Soil drying triggers changes
in water status and results in shift in water uptake. Thus, measurements of tree water status in high-temporal resolution
can improve ours understanding of short-term shifts in tree water sources. High-temporal resolution measurements of
tree water deficit offer new opportunities to understand patterns in tree water use when combined with stable isotopes.
Third, phloem water is more depleted in heavy isotopes than xylem water. The difference between phloem and xylem
water is larger during phloem water refilling and in periods of tree water deficit. These observations led to proposing
a phloem refilling hypothesis and illustrated the need to better understand water transport within trees and potential
isotope fractionation associations, as well as how this can affect tree water use observations. Fourth, this dissertation
proposes a simple method to identify transpiration phenological phases in the boreal forest. This approach shows
good alignment and agreement with timing of phenological changes also observed with ecosystem evaporation fluxes,
and canopy phenological processes. Lastly, the onset of stem rehydration and transpiration overlap with snowmelt,
the largest hydrological event in northern ecosystems. Trees seem to rely on snowmelt water to start transpiring and
snowmelt isotopic signatures dominate the transpiration stream in subsequent weeks. This investigation also showed
that source water signatures in the xylem are controlled by tree water transit times. The high-temporal resolution observations
of tree water use along with the understanding of tree hydrodynamics suggests that ecohydrological separation
illustrates the different velocities of flow paths, influenced by dynamic tree water use in space. Overall, through the coupled tree hydrodynamic measurements of tree water transport and water status, transpiration phenology, and stable
isotope dynamics of trees, this research has advanced the understanding of tree water use in space and time
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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