1,721,014 research outputs found
Structure Determination of Seiridin and Isoseiridin, Phytotoxic Butenolides From Culture Filtrate of Seiridium-cardinale
No full textsiridin (1) and isoseiridin (2) are two new phytotoxic Aa.B-butenolides isolated from culture filtrates of Seiridium cardinale, the causal agent of the cypress canker disease.
Spectroscopic data of the two metabolites and of some key derivatives and the application of Mosher's method provided the complete stereostructure of both products
Fusicoccin structure-activity relationships: stimulation of growth by cell enlargement and promotion of seed germination
No full textThe activity of a number of fusicoccin derivatives and analogues has been assayed on growth by cell enlargement and on proton extrusion in pea (Pisum sativum L, cv. Alaska) internode segments, on growth by cell enlargement in isolated squash (Cucurbita maxima Dechesne in Lam. variety Mantovana) cotyledons, and on germination of light-requiring lettuce (Lactuca sativa L. cv. Grand Rapids) and of abscisic acid-inhibited radish (Raphanus sativus L. variety Tondo Rosso Quarantino) seeds. A similar pattern of activity in the different tests was found for most fusicoccin derivatives and analogues. As with fusicoccin, the activity of its derivatives and analogues on growth of pea internodes is paralleled by the activity on the capability of the tissue to acidify the incubation medium. The obtained data are in full agreement with the view that the activity of fusicoccin on different physiological processes depends on its primary activation of a single system, involved in proton extrusion
New Phytotoxic Butenolides Produced By Seiridium-cardinale, the Pathogen of Cypress Canker Disease
No full textTwo new butenolides, seiridin andiso-seiridin, were isolated from culture filtrates ofSeiridium cardinale, the pathogen of cypress canker, a destructive disease ofCupressus and relatedConiferae These metabolites were characterized as 3-methyl-4-(2-hydroxyheptyl)-2(5H)-furanone and its 4-(3-hydroxyheptyl) isomer, respectively. Chlorotic, and necrotic symptoms were produced on leaves of either host or non-host test plants by absorption of 0.3 mg/ml solutions of either compound. These also showed antibacterial activity
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
- …
