1,720,963 research outputs found
Challenge studies in chickens to evaluate the efficacy of commercial Newcastle disease vaccines against the strains of Newcastle disease virus prevalent in South Africa since 2002
Get PDFDissertation (MSc (Veterinary Science))--University of Pretoria, 2009.Since 2002, the South African poultry industry has experienced outbreaks of Newcastle disease (ND) caused by a newly introduced virus (NDV) strain belonging to lineage 5d/VIId (“goose paramyxovirus” - GPMV). Control of the disease has proved difficult with commercially available vaccines appearing ineffective. In the first of two studies, broilers chicks were vaccinated with VG-GA vaccine (lineage II), then challenged with both GPMV and a “classic” challenge virus (RCV) of lineage 3d/VIII to compare the efficacy of the vaccine against both strains. In the second study, commercial and SPF hens in lay were vaccinated with La Sota vaccine and challenged with GPMV isolate, and immunohistochemistry staining used to determine the distribution pattern of viral antigen in the oviduct of the hens. The second study also compared the efficacy of cloacal and ocular routes of vaccination. The first study did not detect any statistically significant difference in protection offered by the vaccine against the GPMV strain in comparison to the RCV strain. The protection offered by the vaccine against challenge with both viruses was found to be dosedependant with 106.0 EID50 producing a 100% protection and 94.44% and 13.89% for 104.5 EID50 and 103.0 EID50 vaccination doses respectively. Protected birds did not manifest clinical signs, but still had macropathological lesions in some organs at necropsy. The computed protective doses (PD50 and PD90) for the VG-GA vaccine were 103.51 and 104.38 for GPMV and 103.79 and 104.43 for RCV. Results from the second study showed no clear difference in the protection of the oviduct from challenge with GPMV by either the cloacal and ocular routes of vaccination. Vaccinated birds were fully protected (100%) against challenge by La Sota vaccine, but not against infection and replication of the virus, as birds showed varying degrees of macropathology with numerous stained viral antigens in the oviducts demonstrated by immunohistochemistry. The susceptibility and colonisation of the oviduct of laying hens by both the lentogenic La Sota and the virulent NDV isolates was confirmed, with the uterus being more susceptible than magnum and isthmus. Necrosis and apoptosis of cells of the oviduct were not detected but cellular infiltration, gland dilatation and interstitial oedema were observed.Production Animal Studiesunrestricte
Avian poxvirus in a free-range juvenile speckled (rock) pigeon (Columba guinea)
Get PDFA flightless wild juvenile rock pigeon (Columba guinea) with pox-like lesions was picked up on
the premises of the Faculty of Veterinary Science, University of Pretoria, Onderstepoort. The
pigeon was housed overnight for possible treatment the following day but died before any
other intervention could be instituted. At necropsy, coalescing masses of yellowish nodular
cutaneous tumour-like lesions principally on the featherless areas were noticed on the dead
pigeon’s head as well as the beak. Histological examination of the sampled skin lesions revealed
multifocal areas of hypertrophic and hyperplastic epidermal epithelial cells with eosinophilic
intracytoplasmic inclusion bodies (Bollinger bodies). Extract from the lesion was processed and
inoculated on the chorioallantoic membranes (CAM) of 11-day-old embryonated chicken eggs
and this produced pocks on one of the CAM at day 7 post-inoculation. Electron microscopy
confirmed the presence of poxvirus in the CAM with the pock lesions.http://www.jsava.co.zaam201
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
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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