1,720,980 research outputs found
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
Occurrence and significance of fungi associating with mycotrophic plants
No full textMycorrhizal symbiosis represents one of the most important symbioses in the plant kingdom. It is a mutualistic interaction between plant roots and filamentous fungi, where fungal partner provides mineral nutrients, water and often improved protection against pathogens and plants supply fungi with photosynthetic assimilates. Besides mycorrhizal fungi, plants interact with a miscellaneous group of non-mycorrhizal root associated fungi, so called fungal endophytes. Notwithstanding ubiquity and possible importance of root associated fungi, their interactions with host plants have not been hitherto satisfactorily studied. The present Master thesis contains three papers and is aimed on two interesting topics contributing to unveiling different roles of mycorrhizal symbioses in ecological significance of plants and their survival and fitness in specific environments: (i) to address the potential role of ectomycorrhizal fungi and Ericaceae plants in facilitating the invasion of Pinus strobus and (ii) to identify mycorrhizal and non-mycorrhizal fungi associated with endangered orchid and aquatic plants. We assessed diversity and communities' composition of mycorrhizal and non- mycorrhizal fungi using classical culture-dependent approaches as well as modern culture- independent techniques. Results from the first..
Can anatomy and morphology of seagrass root systems predict their colonization by symbiotic fungi?
Get PDFSeagrasses are narrow ecological and taxonomic group of plants which evolved from terrestrial ancestors some 100 million years ago. Unlike most terrestrial plants they are traditionally considered as a group not forming mycorrhizal symbioses or specific root endophytic associations. However, this opinion is likely biased by a very low number of studies targeting this group of vascular plants. For example, an anatomically and morphologically unique endophytic fungal symbiosis was recently discovered in the roots of the Mediterranean endemic species Posidonia oceanica, a species that is considered to be one of the best studied. It thus seems that more specialized research can yield similar results, i.e. discoveries of new fungal association in seagrasses. This could have a big impact on our opinions regarding not only mineral nutrition of these fascinating plants. The aims of this thesis therefore are 1) to summarize published information about fungal associations in the roots of seagrasses, 2) to summarize basic knowledge of anatomy and morphology of the roots of individual groups of seagrasses and 3) an attempt to predict seagrass groups where we may more likely assume presence of fungal associations. Special emphasis will be placed on the genus Posidonia which has an evolutionary origin in the..
Nádorovka infikující mořskou trávu Halophila stipulacea: fylogeneze, distribuce a nové poznatky o životním cyklu
Get PDFMarine phytomyxids (Cercozoa: Phytomyxea) represent a group of obligate biotrophic eukaryotes known for infecting several algae and oomycetes and counted among three taxa generally reported to behave as seagrass-pathogens. Due to their low-key nature, they are observed only sporadically and very limited information about their diversity, life cycles or distribution is available. In order to extend the knowledge of this enigmatic group of marine protists, an extensive research on a phytomyxid found in the invasive seagrass Halophila stipulacea was carried out. In situ observations, light and scanning electron microscopy and molecular methods were used to approach the species' ecology, geographical range and phylogenetic placement within the class Phytomyxea. The organism was confirmed to be present in the Red, the Mediterreanean and the Caribbean Sea, suggesting a potential case of a host-parasite comigration on a global scale. Phylogenetically it represents the first and so far the only described member of the "TAGIRI-5 environmental clade" - possibly a whole new order within the Phytomyxea, outside the already established Plasmodiophorida and Phagomyxida. The infection rates and times of occurrence are specified for all the finding-sites, indicating an interesting seasonal pattern in the...1 ABSTRAKT Mořské nádorovky (Cercozoa: Phytomyxea) představují skupinu obligátních, biotrofních eukaryot parazitujících na řasách, oomycetech a řadící se mezi tři taxony, obecně považované za patogeny mořských trav. Kvůli svému nenápadnému vzhledu bývají v přírodě pozorovány pouze ojediněle a o jejich diverzitě, distribuci či životních cyklech je dodnes dostupných jen velmi málo informací. Za účelem širšího porozumění těchto záhadných mořských protistů byl v rámci této práce proveden rozsáhlý výzkum nádorovky napadající invazní mořskou trávu Halophila stipulacea. K přiblížení její ekologie, zeměpisného rozšíření a fylogenetického zařazení v rámci třídy Phytomyxea byla použita široká škála metod, zahrnující pozorování in situ, světelnou a elektronovou mikroskopii a molekulární analýzy. Přítomnost daného druhu byla potvrzena v Rudém, Středozemním i Karibském moři, naznačujíc možnou souběžnou migraci parazita s hostitelem v globálním měřítku. Z fylogenetického hlediska představuje tato nádorovka prvního a dosud jediného popsaného zástupce environmentální skupiny "TAGIRI-5", která, vedle již ustanovených řádů Plasmodiophorida a Phagomyxida, tvoří zřejmě zcela novou větev třídy Phytomyxea. Shromážděná data o promořenosti jednotlivých zkoumaných populací mořských trav a období výskytu infekce vykazují zajímavý...Department of EcologyKatedra ekologiePřírodovědecká fakultaFaculty of Scienc
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
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