1,720,964 research outputs found
Genetic structure and phylogeny of Italian and Czech populations of the cucurbit powdery mildew fungus Golovinomyces orontii inferred by multilocus sequence typing
No full textCucurbit powdery mildew caused by Golovinomyces orontii is a serious disease that affects cucurbit crops in temperate
areas. In northern Italy, the species is responsible for the early infections at the beginning of the growing season. However,
chasmothecia have never been recorded in Italy and the impact of either asexual or sexual reproduction of
G. orontii remains to be determined. To investigate and compare the genetic structure of Italian populations with those
from the Czech Republic, where chasmothecia are sporadically recorded, seven housekeeping gene fragments (tef-1a,
csI, ITS, H3, tub2, IGS and mtLSU) were amplified and used in a multilocus sequence typing (MLST) approach. The
four-gamete test was performed to detect recombination between and within populations. Phylogeny was inferred using
both Bayesian and minimum evolution analyses. Results from MLST revealed the presence of 141 single nucleotide
polymorphisms and the existence of 13 different haplotypes. Phylogenetic analysis revealed the existence of two main
distinct phylogenetic groups that were also highly genetically different, confirming that G. orontii is a species complex.
Recombination was detected within both the phylogenetic groups and the geographical populations, indicating that
sexual reproduction could have occurred. However, considering the lower haplotype diversity and the high frequency
of ST3 (17 isolates) and ST7 (eight isolates) haplotypes, the Italian population could be predominantly clonal, while
sexual reproduction may occasionally occur due to the introduction of genotypes similar to those from the Czech
Republic
Ekologie litoralnich ras.
No full textAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi
Seasonal dynamic of the phytoplankton in two fishponds near Protivanov (Moravia, the Czech Republic)
No full textThe contribution presents the results of the first investigation of phytoplankton in the district of Prostějov. During 1998-1999 seasonal changes of phytoplankton in two fishponds together with selected physical and chemical parameters (temperature, oxygen, pH, conductivity, nutrients and heavy metals) were investigated. Eutrophication of the investigated fishponds is not as high as in other regions in the Czech Republic
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
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