1,720,976 research outputs found
Metamitron resistant Chenopodium album: characterisation, detection and distribution in Belgian sugar beet
No full textSince the late 1990’s, we observed unsatisfactory control of Chenopodium album L. (fat hen; a highly competitive and prolific weed species) in several sugar beet fields in Belgium and, to some extent, in other European countries.
Failing C. album control might be attributed to evolved resistance to metamitron, a key herbicide in sugar beet. The research objectives were: (1) identification and characterisation of metamitron resistant C. album, (2) development of detection methods and (3) estimation of the spatial distribution of metamitron resistant C. album in Belgian sugar beet.
(1) We detected two metamitron target-site resistant C. album biotypes. The serine264 to glycine mutated biotype is moderately to highly (cross) resistant to metamitron, metribuzin and terbuthylazine (or atrazine). We identified this biotype in Belgian, French and Dutch C. album populations from sugar beet. We detected the alanine251 to valine mutated biotype in Swedish populations only and characterised it as highly resistant to metamitron and metribuzin but only low level cross resistant to terbuthylazine. To our knowledge, field selected plants with resistance to herbicides due to an alanine251 to valine mutation on the psbA gene were never before reported or characterised. (2) To detect and distinguish between the two identified metamitron resistant biotypes, we developed three quick detection methods based on chlorophyll fluorescence measurements, CAPS analysis and single dose bioassays, respectively. (3) Finally, we found that the incidence of the serine264 to glycine mutated biotype extends over the whole Belgian sugar beet area. Moreover, the resistant biotype is highly prevalent in fields with unsatisfactory C. album control (representing 20% of the sugar beet area in 2008). Although we demonstrated that the FAR-system used in sugar beet is still able to control the resistant biotype, we also confirmed the major role of metamitron resistance in unsatisfactory C. album control.Chenopodium album L. (melganzenvoet) is een erg competitief onkruid met hoge zaadproductie en komt frequent voor in o.a. suikerbiet en aardappel. Sinds eind jaren ’90 stelden we een gebrekkige bestrijding van C. album vast in meerdere suikerbietvelden in België en – in mindere mate – elders in Europa.
Een mogelijke verklaring voor de falende C. album bestrijding is het ontstaan van resistentie tegen metamitron, een sleutelherbicide in suikerbiet. De doelstellingen van ons onderzoek waren: (1) identificatie en karakterisatie van metamitronresistente C. album, (2) ontwikkeling van snelle detectiemethodes en (3) schatting van de verspreiding van metamitronresistente biotypes over het Belgische suikerbietareaal.
(1) We detecteerden twee C. album biotypes met target-site resistentie tegen metamitron. Het serine264 naar glycine gemuteerde biotype heeft een matige tot hoge (kruis)resistentiegraad tegen metamitron, metribuzin en terbuthylazin (of atrazin). We vonden dit biotype in Belgische, Franse en Nederlandse C. album populaties uit suikerbiet. Het alanine251 naar valine gemuteerde biotype identificeerden we enkel in Zweedse populaties en karakteriseerden we als zeer resistent tegen metamitron en metribuzin maar slechts licht resistent tegen terbuthylazin. In het veld geselecteerde planten met resistentie tegen herbiciden door een alanine251 naar valine mutatie op het psbA-gen werden, voor zover we weten, nooit eerder gerapporteerd. (2) Om de twee geïdentificeerde metamitronresistente biotypes te detecteren en van elkaar te onderscheiden, ontwikkelden we drie snelle detectiemethodes gebaseerd op resp. chlorofylfluorescentie metingen, CAPS analyse en 1-dosis biotoetsen. (3) Tot slot stelden we vast dat het serine264 naar glycine gemuteerde biotype verspreid over het hele Belgische suikerbietareaal voorkomt. Het biotype heeft bovendien een hoge prevalentie binnen velden met een gebrekkige C. album bestrijding (die in 2008 20% van het bietenareaal uitmaakten). Hoewel we aantoonden dat het FAR-systeem in suikerbiet nog in staat is om het resistente C. album biotype te bestrijden, werd de belangrijke rol van metamitronresistentie bij gebrekkige C. album bestrijding in suikerbiet bevestigd
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
Cross-resistance profile of metamitron-resistant Chenopodium album L. biotypes from sugar beet
No full textAuthor-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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