1,720,958 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
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
Pyrenophora tritici-repentis the causal agent of tan spot: characterisation of New Zealand populations
No full textTan spot, caused by the ascomycete fungus Pyrenophora tritici-repentis, is one of the most economically significant and devastating foliar diseases of wheat. In this study, the distribution, genetic diversity and race structure, sensitivity to commonly used fungicides and virulence on different wheat cultivars of P. tritici-repentis was investigated.
A total of 15 different populations of P. tritici-repentis were collected during the 2013-2014 survey period. The survey showed that P. tritici-repentis was widely distributed throughout the South Island of New Zealand. A follow-up farmer questionnaire revealed that the re-use and sowing of untreated wheat seed and continuous sowing of wheat over 10-20 years may have exacerbated tan spot infestations.
A total of 12 single spore P. tritici-repentis isolates were chosen to represent the geographic distribution and diversity of P. tritici-repentis in New Zealand. The identities of all isolates were confirmed through sequencing of the internal transcribed spacer (ITS), β-tubulin regions and species specific (PtrUnique) PCR primer products. All New Zealand P. tritici-repentis isolates had the Ptr ToxA gene ToxA, but lacked the Ptr ToxB gene ToxB. This result indicated that the New Zealand isolates most likely belonged to virulence races 1 or 2. Results were confirmed by comparing New Zealand isolates against a range of fully characterised P. tritici-repentis international isolates.
Three different molecular methods (UP-PCR, RAPD and microsatellite analysis) were utilised in this study to assess genetic diversity of a range of New Zealand and international P. tritici-repentis isolates. A total of 13 different genotypes were detected with all three methods using 12 different primers from all of the New Zealand and international P. tritici-repentis isolates. Although all three methods provided different levels of information, they indicated that the genetic structure of the South Island populations of P. tritici-repentis was clonal. The New Zealand isolates were genetically distinct when compared to a range of international P. tritici-repentis isolates. These results suggested that New Zealand populations of P. tritici-repentis either do not undergo frequent genetic recombination or were part of a recent incursion. However, the exact explanation could not be identified.
The in vitro fungicide bioassay showed that all ten of the assessed fungicides effectively reduced the in vitro mycelial growth of P. tritici-repentis to <50%. The fungicides isopyrazam, propiconazole and prothioconazole had the lowest EC50 values which indicated they were the most effective fungicides against P. tritici-repentis.
The inoculation of ten wheat cultivars in a glasshouse environment with P. tritici-repentis revealed that at least eight of the ten cultivars were susceptible to tan spot. Of the ten wheat cultivars assessed, Empress and Duchess had the lowest disease severity and displayed symptoms characteristic of resistance towards P. tritici-repentis.
Overall, this study has provided a new insight into the current distribution, genetic diversity and race structure, sensitivity to a broad range of fungicides and virulence on a range of commonly cultivated wheat cultivars of P. tritici-repentis in New Zealand. The findings of this study will also provide wheat growers with valuable knowledge that will facilitate the development and implementation of future tan spot control strategies in New Zealand
Contribution of white clover hosts to the effectiveness of rhizobia symbioses : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
Full text linkWhite clover (Trifolium repens L.) is an integral component of mixed pastures in New Zealand temperate agriculture, providing quality feed and a sustainable source of fixed nitrogen (N) through its symbiosis with strains of Rhizobium leguminosarum bv. trifolii. While there has been much focus on identifying and applying Rhizobium strain inoculants for improved N-fixation, there has been less attention on identifying and exploiting plant genetic factors to develop cultivars that can consistently form effective Rhizobium symbioses. The complexity of the clover-Rhizobium interaction makes for a challenging but valuable breeding target which represents an important strategy for increasing the sustainability of New Zealand’s pasture-based agriculture.
In this study, the phenotypic variation of N-fixation capacity across individuals from 17 white clover cultivars, including a wild ecotype (‘Tienshan’) and a T. repens × T. uniflorum interspecific hybrid cultivar (‘AberLasting’), released between 1920 and 2003 and representing three leaf size classes were investigated. N-fixation capacity was assessed by growing plants in vermiculite/McKnight’s solution, where N was provided either by an effective commercial strain (TA1) or partially effective (S12N10) N-fixing Rhizobium strain or supplied mineral N (positive control). Symbiotic traits recorded after 35 days of growth included Shoot and Root dry matter (DM), root to shoot ratio (RSR), and symbiotic potential (SP) which is the proportion of biomass generated through symbiosis relative to plants grown with mineral N. There were significant differences or interactions between and among cultivars and Rhizobium strains. Furthermore, there was a high degree of variability in N-fixation capacities of individuals within the cultivar populations. Multivariate analysis clustered cultivars across an N-availability gradient and identified some cultivars that performed equally well (‘S100’) or equally poorly (‘Barblanca’) or had marked differential performance (‘Dutch’ and ‘Tienshan’) across effective or partially effective strains.
In order to derive key quantitative genetic parameters which could be utilised for improving N-fixation in white clover, a genetically structured F3 population of half-sibling (HS) families (n = 120) underwent the same screening assay as in the previous study, with N being provided either by the commerical strain TA1 or supplied mineral N (positive control). Shoot and Root DM, SP as well as RSR were measured and differed considerably among HS families, with 44% of families forming sub-optimal symbioses with TA1. Best linear unbiased predictor (BLUP) means for all traits were derived for each HS family and used to estimate significant additive variation and narrow-sense heritabilities, which ranged from 0.05 (RSR) to 0.33 (Shoot DM). This indicated there is additive genetic variability that can be exploited for improving the symbiotic interactions. These estimates also enabled the genetic gain for the examined traits to be predicted at 20%, 10% and 5% selection pressures while also identifying 24 elite HS families that could be utilised in future selection validation work.
The feasibility of applying genomic selection (GS) for improving genetic gain in white clover-Rhizobium associations using a HS family structure was investigated. The phenotypes of 118 HS families and a genomic relationship matrix derived from ~155,000 genotyping-by-sequencing single nucleotide polymorphism markers of the HS families’ corresponding maternal parents were used for genomic prediction (GP) using five models. Cross-validation predictive ability (PA) of symbiotic traits ranged from 0.14 (Root SP) to 0.36 when two traits (Shoot DM and Shoot SP) were combined into a multi-trait Smith-Hazel selection index. The PAs of the five GP models were similar across all traits and therefore the computationally efficient GP model Kinship using GBS with depth adjustment-GBLUP (KGD-GBLUP) was selected. Different parameters influencing PA were assessed and identified a minimum of 94 HS families using a training: test combination of 80: 20%, respectively, over 100 iterations was sufficient for generating PAs in this population. This work provides an ideal foundation to assess genomic selection for breeding white clover germplasm for improved N-fixation and productivity by undertaking among-(using phenotype) and-within (using GS) HS family selection.
To determine relationships between performance with pure strains and soil communities, a subset of cultivars (n = 4) and HS families (n = 4) screened previously for differential N-fixation capacities were assessed with two pure strains (TA1 and S12N10) and five soil rhizobia extracts. Differences in the N-fixation capacities with pure strains reflected those from the previous experiments. While there was considerable variation in symbiotic traits among populations with the five soil extracts, performance with the effective Rhizobium strain TA1 was often indicative of performance with the soil communities. Using multivariate pattern analysis, distinct clusters among the white clover populations were identified, which appeared to be driven by the number and appearance of nodules.
In summary, the findings of this thesis will provide valuable information for facilitating the improvement of N-fixation in white clover in future breeding efforts
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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