1,720,958 research outputs found
A single polymerase (L) mutation in avian metapneumovirus increased virulence and partially maintained virus viability at an elevated temperature
No full textPreviously a virulent avian metapneumovirus (AMPV) farm isolate Italy 309/04 was shown to have derived from a live vaccine. Virulence due to the five nucleotide mutations associated with the reversion to virulence, was investigated by their addition to the vaccine using reverse genetics. Virulence of these recombinant viruses was determined by infection of one-day-old turkeys. Disease levels resulting from the combined two matrix (M) mutations was indistinguishable from that produced by the recombinant vaccine, whereas the combined three L gene mutations increased disease to a level (p<0.0001) which was indistinguishable from that caused by the revertant Italy 309/04 virus. Testing of the L mutations individually showed that two did not increase virulence while the third, corresponding to an asparagine to aspartic acid substitution, produced virulence indistinguishable from that caused by Italy 309/04. In contrast to the vaccine, the virulent mutant also showed increased viability at temperatures typical of turkey core tissues. The notion that increased viral virulence resulted from enhanced ability to replicate in tissues away from the cool respiratory tract, cannot be discounted
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
Evidence of AMPV attachment protein evolution coincident with mass live vaccine introduction in Italy
No full textAvian metapneumoviruses (AMPV) of subtype B dominate over other subtypes on Italian poultry farms in northern Italy. AMPVs from the Veneto region of Italy between 1987 and 2007 were sequenced in their attachment (G) and fusion (F) protein genes,
together with other subtype B AMPVs from other parts of Western Europe, collected prior to 1994. All viruses in the survey had very similar predicted F sequences whereas the predicted G protein sequences found in Italy from 2001 were distinctly different from those found in pre 1994 viruses. Nonetheless pre 1994 Italian AMPVs were more similar to post 2000 AMPVs than other pre 1994 viruses from other parts of Europe, thereby showing that the later viruses had probably evolved from early Italian viruses. The occurrence of the later variants followed introduction of the mass
administration with a single subtype B vaccine and its G protein sequence placed it clearly in the pre 1994 cluster. The possibility of the vaccine having driven field virus evolution in order to evade immune pressure cannot be excluded
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
The development of a subtype B AMPV reverse genetics system
No full textA reverse genetics system is the only available method to introduce specific mutations into the AMPV genome. To date no system for the AMPV subtype B had been reported. In the system described, plasmids for N, P, M2, the polymerase and the full genome were constructed under the control of the T7 promoter. Producing intact clones containing the virus polymerase gene proved highly technically demanding due to the issue of them containing sequences toxic to bacteria, thus
leading to sections of the gene being spontaneously deleted. Nonetheless, once all clones had been generated and transfected into Vero cells previously infected with a fowlpox recombinant
virus expressing T polymerase, AMPV was recovered
- …
