1,720,987 research outputs found
Biocompetition as a tool to cope with the problem of aflatoxin contamination of food and feed commodities: may phenotype microarray technology contribute to the individuation of "good" competitors?
No full textAspergillus flavus is a well known plant pathogen responsible of economic losses and food safety concern due to the ability of mycotoxin production. Aflatoxin contamination of crops is a significant problem worldwide, and many Countries have set more or less strict limits for mycotoxin presence in feed and food commodities. An interesting strategy to cope with aflatoxin contamination in susceptible crops involves the use of intraspecific competition to interfere with mycotoxin production by the relevant Aspergillus flavus strains. Atoxigenic A. flavus strains (afla-), unable to produce the relevant mycotoxin, have been already used as bio-competitors to decrease aflatoxin accumulation on cotton, maize and peanuts fields. Selecting a strain performing as a strong bio-competitor is not a straightforward task since it depends on previous assessment of various interacting factors conditioning the relative fitness of the strains in a given ecological niche. Reconstruction experiment have been generally performed in laboratory conditions to uncover the biological mechanisms underlying the efficacy of atoxigenic strains in preventing aflatoxin production and/or to give a preliminary indication of strain performance when released in the field.
Our present goal is 1) characterization of A. flavus population colonizing the corn field of the Po valley and 2) setting a strategy for the identification of “good” competitors among afla- strains isolated from the above mentioned A. flavus population. For this purpose we are performing competition experiments in laboratory conditions and designing “high throughput” procedures to test as many as possible environmental conditions that may affect competition efficacy. Moreover, afla- strains are generally considered to be derived from aflatoxin producer strains (afla+) that have lost the capacity to produce the relevant mycotoxin as a result of mutation(s) affecting gene(s) belonging to the Aflatoxin biosynthetic cluster. afla- strains are obviously expected to be altered in one or more steps of secondary metabolism. However the story might be more complex than expected, since regulatory interactions between pathways of primary and secondary metabolism have already been described. In this respect, Phenotype MicroArray technology may represent an additional value for our goal if the specific metabolic features of different afla- strains could be correlated to their competitive ability. In the present study we have performed, as a preliminary approach, experiments to verify if afla+ and afla- strains may be differentiated by the use of the Biolog FF physiological identification kit
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
Impiego di Microstation (Biolog): creazione ed applicazione di un database per differenziare Penicillium verrucosum da Penicillium nordicum.
No full textDispelling 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
Immunoaffinity clean-up and direct fluorescence measurement of aflatoxins B1 and M1 in pig liver: comparison with high-performance liquid chromatography determination
No full textAn improved analytical method for aflatoxin B-1 ( AFB(1)) and aflatoxin M-1 ( AFM(1)) determination in pig liver is described, using an aqueous methanol extraction, an immunoaffinity column clean-up step and a direct fluorometric measurement for toxin detection and quantification. A detection limit of 1.0 mu g kg(-1) was achieved for AFB(1) and AFM(1). Mean recoveries of 80.7 +/- 9.0% for AFB(1) spiked at 1.0-9.7 mg kg(-1) levels and of 76.7 +/- 6.6% for AFM1 spiked at 1.0-5.5 mg kg(-1) levels were obtained. Recovery data for spiked samples were statistically compared with those obtained by the same extract using classical reversed-phase high-performance liquid chromatography ( RP-HPLC) with fluorescence detection, showing a significant correlation ( p <= 0.05) for both aflatoxins. Both procedures were applied to the analysis of 50 pig livers, collected from 10 farms in the north of Italy. All the samples showed a contamination level lower than 1.0 mu g kg(-1) for AFB(1) and one liver sample has shown an AFM(1) contamination greater than 1.0 mg kg(-1). The direct fluorometric procedure is particularly suitable for food manufacturers and control laboratories where quick procedures are mainly required for food quality control as well as for diagnostic and research purposes
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
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