1,720,987 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
Small RNA profiling of grapevine leafroll-associated virus 3 infected grapevine plants
Full text linkThesis (PhD)--Stellenbosch University, 2016.ENGLISH ABSTRACT: One of the most important viral diseases of grapevine worldwide is grapevine leafroll disease (GLD).
A number of viruses from the family Closteroviridae have been associated with this disease, though
Grapevine leafroll-associated virus 3 is considered the leading causative agent due to its consistent
association with GLD. To better understand the disease and develop effective control strategies, it is
necessary to characterise the molecular interactions between the virus and the plant. Small RNA
(sRNA) molecules have been shown to play an important role in gene regulation of normal
development and defence responses to biotic and abiotic stresses in plants. Therefore, the aim of this
study was to characterise the sRNA species in healthy and infected grapevine to contribute to the
growing database of sRNAs present in Vitis vinifera. Microarray analysis and next-generation
sequencing was used to identify sRNA species in Chardonnay, Chenin blanc, Cabernet Sauvignon and
own-rooted Cabernet Sauvignon plants. Differential expression of sRNAs was evaluated to identify
sRNAs associated with GLRaV-3 infection. The modulation of the differentially expressed
microRNAs (miRNAs) was validated with stemloop RT-qPCR assays. Transcriptome NGS was also
performed to validate the differential expression of the predicted miRNA targets, and to identify
metabolic pathways modulated in response to GLRaV-3 independently from sRNA regulation. The
transcriptome NGS transcripts that were differentially expressed in all cultivar groups, and transcripts
that anti-correlated with miRNA expression, were validated with RT-qPCR assays. These highthroughput
approaches identified several differentially expressed sRNAs and (target) genes in infected
plants. The anti-correlation of miRNA expression and putative target expression were shown for two
miRNAs. Cultivar specificity was identified in the sRNA and gene expression analyses, and both
approaches identified Chenin blanc-specific responses. This comparison of symptomatic and
asymptomatic GLRaV-3-infected plants provides the first insight into the disease symptom inhibition
observed in certain cultivars. The differentially expressed genes identified in all cultivar groups, using
the NGS transcriptome data, provides a collection of genes displaying a potentially universal molecular response against GLRaV-3. These genes showed strong associations with cell wall
biosynthesis and signalling during pathogen recognition. This study has contributed significantly to
the knowledge of sRNAs produced in grapevine and significantly extended the existing sRNA
reference database for grapevine. The knowledge generated in this study can be utilised as potential
targets for grapevine functional studies, and be translated into potential management strategies to
control the disease. A better understanding of both the host defence and viral counter-defence
strategies can lead to the prevention of virus replication or the impaired ability of the virus to induce
pathogenesis in plants.AFRIKAANS OPSOMMING: Een van die belangrikste virussiektes van wingerd wêreldwyd is wingerd-rolblaarsiekte (GLD). 'n
Aantal virusse van die familie Closteroviridae hou verband met hierdie siekte, maar Grapevine
leafroll-associated virus 3 (GLRaV-3) word beskou as die hoof-bydraende faktor van GLD as gevolg
van die korrelasie met GLD. Om die siekte beter te verstaan en effektiewe beheer toe te pas, is dit
nodig om die molekulêre interaksie tussen die virus en die plant te ondersoek. Klein RNA (sRNA)
molekules het getoon dat hulle 'n belangrike rol speel in die geenregulering van normale plant
ontwikkeling, asook tydens die plant se verdediging teen biotiese en abiotiese stresfaktore. Die doel
van hierdie studie was dus om die sRNA spesies in gesonde en geïnfekteerde wingerdstokke te
karakteriseer en sodoende by te dra tot die snelgroeiende databasis van Vitis vinifera sRNAs. ‘n
Mikro-DNA-volgorde-raamwerk analise, asook nuwe-generasie volgordebepaling (NGS) is gebruik
om sRNAs spesies te identifiseer in die kultivars Chardonnay, Chenin blanc, Cabernet Sauvignon en
eie-gewortelde Cabernet Sauvignon plante. Daarna is die differensiële uitdrukking van sRNAs
geëvalueer om sodoende sRNAs te identifiseer wat verbandhou met GLRaV-3 infeksie. Die regulering
van die differensiële uitgedrukte mikroRNA’s (miRNAs) is bevestig met stam-lus tru-transkripsie
kwantitatiewe polimerase ketting reaksie (stemloop-RT-qPCR) toetse. Transkriptoom-NGS is ook
uitgevoer om die differensiële uitdrukking van die miRNAs se voorspelde teikens te valideer en om
gemoduleerde metaboliese paaie in reaksie op GLRaV-3, onafhanklik van sRNA regulasie, te
identifiseer. Die transkriptoom NGS gene wat differensieël uitgedruk was in al die kultivar groepe,
asook die gene wat ’n anti-korrelasie getoon het met miRNA uitdrukking, is bevestig met RT-qPCR
toetse. Hierdie hoë-deurset benaderings het verskeie sRNAs en gene geïdentifiseer wat differensieël
uitgedruk was in geïnfekteerde plante. Die anti-korrelasie van miRNA uitdrukking en voorspelde
teiken uitdrukking is geïdentifiseer vir twee miRNAs. Kultivar-spesifisiteit was geïdentifiseer in beide die sRNA en geenuitdrukking analises en beide benaderings het ook Chenin blanc-spesifieke reaksies
geïdentifiseer. Hierdie vergelyking van simptomatiese en asimptomatiese GLRaV-3-geïnfekteerde
plante bied die eerste insig in die simtoom-inhibisie wat waargeneem word in sekere kultivars. Die
differensieël-uitgedrukte gene wat geïdentifiseer was in alle kultivar groepe, met behulp van die NGS
transkriptoom data, bied 'n versameling van gene wat ‘n potensiële universele molekulêre reaksie toon
teen GLRaV-3. Hierdie gene het sterk assosiasies met selwand-biosintese en patogeen
herkenningseine. Hierdie studie het aansienlik bygedra tot die kennis van wingerd-geassosieerde
sRNAs en dra beduidend by tot die uitgebreide sRNA databasis. Die kennis wat gegenereer is in
hierdie studie kan gebruik word om teikens te identifiseer vir wingerd funksionele studies en om
verwerk te word na potensiële strategieë om die siekte te beheer. 'n Beter begrip van beide die gasheer
verdedigings- en die virale teen-verdedigingstrategieë, kan lei tot die voorkoming van virus replikasie
of ‘n verlaging in die vermoë van die virus om die siekte in plante te veroorsaak.Doctora
Sequencing and detection of a new strain of grapevine leafroll-associated virus 3 in South Africa
Full text linkThesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Grapevine leafroll-associated virus 3 (GLRaV-3) is the type member of the genus Ampelovirus in the family Closteroviridae and is considered to be the main contributing agent of grapevine leafroll disease (GLD) worldwide. A metagenomic sequencing study of a grapevine leafroll-diseased vineyard led to the discovery of a new variant of GLRaV-3 in South Africa. This new variant was most related to a New Zealand isolate, NZ-1. In this study, we sequenced two isolates, GH11 and GH30, of the new variant group of GLRaV-3. These isolates have less than 70% nucleotide (nt) identity to other known GLRaV-3 variants, indicating that they should be considered variants of a different strain of GLRaV-3. We propose that the GLRaV-3-like virus identified in this study be grouped together with NZ-1 and some Napa Valley isolates as Group VI of GLRaV-3. This study also provided further evidence that next-generation sequencing is an invaluable approach to identify novel viruses and variants, in that the draft sequence generated with bioinformatic tools in this study was 98% identical to the GH11 sequence generated using Sanger sequencing. The study further confirmed that the industry standard ELISA is still an effective GLRaV-3 diagnostic method and that it is able to detect all known variant groups of GLRaV-3. However, this assay is not able to differentiate between GLRaV-3 variant groups. In the current study therefore, a real-time RT-PCR was designed that is able to detect GLRaV-3 variant groups I, II, III and VI, using a single primer pair targeting the Hsp70h gene of GLRaV-3. If high-resolution melting (HRM) curve analysis is added to the real-time RT-PCR, it is possible to differentiate between variant groups based on three melting point intervals. The RT-PCR HRM assay provides a more sensitive and rapid tool to detect and differentiate between different GLRaV-3 variant groups. Finally, a multiplex RT-PCR was designed to differentiate between the variant groups present in South Africa. This multiplex RT-PCR offers a validation method for the RT-PCR HRM and provides an end-point PCR alternative for variant identification. In order to investigate the spread and impact of different GLRaV-3 variants in vineyards, sensitive diagnostic techniques are a necessity. The abovementioned tools will contribute to the understanding of the pathogenesis of GLD and aid epidemiological studies to investigate how these different GLRaV-3 variant groups are spreading, the association of specific GLRaV-3 variants to disease symptoms and the mealybug vector transmission efficiency for each GLRaV-3 variant.AFRIKAANSE OPSOMMING: Grapevine leafroll-associated virus 3 (GLRaV-3) is ’n lid van die genus Ampelovirus in die familie Closteroviridae en word beskou as die hoof bydraende faktor van wingerd-rolbladsiekte wêreldwyd. ’n Metagenomiese studie het bewys dat daar ’n nuwe variant van GLRaV-3 bestaan wat nog nie voorheen in Suid Afrika opgespoor kon word met die huidige opsporingsmetodes nie. Hierdie nuwe variant was naaste verwant aan ’n Nieu-Seelandse isolaat, NZ-1. In hierdie studie is die genoomvolgorde van twee isolate, GH11 en GH30, van hierdie nuwe GLRaV-3 variant groep bepaal. Hierdie twee isolate was minder as 70% identies aan ander GLRaV-3 variante, wat daarop dui dat hulle as variante van ’n nuwe virus-ras beskou behoort te word. Ons beveel aan dat hierdie GLRaV-3-verwante virus geklassifiseer word saam met die NZ-1 isolaat en ander isolate uit Kalifornië, as groep VI van GLRaV-3. Hierdie studie het ook verdere bewyse verskaf dat volgende-generasie volgordebepalingstegnologie ’n waardevolle benadering is om nuwe virusse en variante te identifiseer, deurdat die huidige studie gewys het dat die voorlopige volgorde, wat gegenereer is deur bioinformatika-instrumente, 98% identies was aan die GH11 volgorde wat met Sanger volgordebepaling verkry was. Hierdie studie het ook gevind dat die industrie-standaard ELISA, nog steeds ’n effektiewe GLRaV-3 diagnostiese metode is en wel infeksies, veroorsaak deur al die variant-groepe, sal kan identifiseer. Die ELISA toets is egter nie in staat om te onderskei tussen GLRaV-3 variant-groepe nie. In hierdie studie is ’n variant-identifiseerbare in-tyd tru-transkripsie polimerase ketting reaksie (PKR) ontwerp wat GLRaV-3 variant-groepe I, II, III en VI kan identifiseer deur middel van ’n enkele inleier-stel wat die GLRaV-3 Hsp70h-geen teiken. As hoë-resolusie smeltingskurwe-analise bygevoeg word by die in-tyd tru-transkripsie PKR, is dit moontlik om te onderskei tussen variant-groepe op grond van drie smeltingspunt intervalle. Die tru-transkripsie hoë-resolusie smeltingskurwe-toets verskaf meer sensitiewe en geoutomatiseerde metodes om GLRaV-3 variant-groepe te identifiseer en te onderskei. ’n Veelvuldige tru-transkripsie PKR is ook ontwerp om tussen variante wat tans in Suid-Afrika aangetref word, te onderskei en te dien as ’n valideringsmetode vir die in-tyd tru-transkripsie hoë-resolusie smeltingskurwe-toets. Sensitiewe en akkurate toetse, soos bogenoemde, is noodsaaklik vir die bestudering van die verspreiding en impak van die verskillende GLRaV-3 variante in wingerd. Hierdie metodes kan gebruik word om kennis ten opsigte van rolblad patogenese te verbreed en om by te dra tot epidemiologiese studies wat ondersoek hoe hierdie variant-groepe versprei, of daar ’n assosiasie bestaan tussen ’n spesifieke variant en siekte-simptome en of daar ’n verskil is in die witluisvektor oordragseffektiwitiet vir elke GLRaV-3 variant.Master
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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