1,721,066 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
Getting the Inside Scoop on Soil Seed Banks
No full textIn this picture, I am photographed in my typical field day during my research experience for undergraduate (REU) at the Smithsonian Tropical Research Institute (STRI) during the summer of 2014. Here, I am shoveling soil from a transect in the 50 ha Barro Colorado Island rainforest census plots that contains a seed bank of a particular Neo-tropical pioneer species. After collection, I would bring the collected seeds back to the labs on Barro Colorado Island to culture fungi, test for viability, germination, conductivity, and physical hardness to answer questions regarding seed dormancy and the role of soil microbes has on long-term persistence. For more information about the Image of Research--Undergraduate Edition go to: http://go.library.illinois.edu/imageofresearch_ureditionSubmitted by Kayla Hays ([email protected]) on 2015-04-30T17:26:08Z
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Previous issue date: 2015-04Ope
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
Genetic analysis of cellobiohydrolase I (cbhI) gene sequences and production of other wood degradation enzymes in tropical aquatic fungal communities
Get PDFDead plant biomass represents a major source of energy supporting aquatic food webs. Fungal communities play an important role in making this energy available through the breakdown of complex plant polymers via hydrolytic enzymes. The objectives of this study were to determine (1) whether aquatic fungi possess cbhI genes for the production of cellobiohydrolase, a major class of cellulolytic enzymes present in terrestrial fungi, and (2) to examine the effects of salinity on the production of wood degrading enzymes in cultures of aquatic fungi grown in vitro. Colonies of seven ascomycete taxa were grown from single spore isolates obtained from wood collected along a freshwater-marine salinity gradient in rivers on Coiba Island, Panama. Primers for cbhI were used to successfully amplify DNA from 4 out of 7 fungal cultures without the need for cloning, suggesting that cbhI is a single-copy gene in Ascomycetes. Four aquatic Ascomycetes, cultured from wood from the same sites, were screened for their ability to produce degradative enzymes on solid media across a salinity gradient. Enzymes tested were: endoglucanase, -glucosidase, and xylanase. Results suggested that salinity affects growth and enzyme production in a species-specific manner. Freshwater taxa grew significantly faster and produced wood degrading enzymes more consistently in less saline environments. In contrast, marine taxa were observed to grow across a range of salinity levels, but had the highest level of enzyme production in more saline environments. This study shows that aquatic ascomycete fungi share at least some of the enzymatic capabilities of their terrestrial basidiomycete counterparts, and that salinity effects on enzyme production may be an important control on aquatic fungal species distribution.Submitted by Heidi Johnson ([email protected]) on 2015-05-26T21:23:08Z
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Previous issue date: 2015-05Ope
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
Seed Banks, Seed Mortality, and the Role of Fungal Communities in Neotropical Forests
No full textIndex words. Ascomycota; Cecropia; fungi; tropical forest ecology; seed bank; pioneer species; pathogens; ITS; Barro Colorado Island, Panama; La Selva, Costa Rica; Yasuni, Ecuador; recruitment limitation.Made available in DSpace on 2015-09-25T22:42:33Z (GMT). No. of bitstreams: 2
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Previous issue date: 2007Embargo set by: Seth Robbins for item 86651
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only128 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007
Plant-soil associations in a lower montane tropical forest: physiological acclimation and herbivore-mediated responses to nitrogen addition
No full textP>1. Soil nutrients influence plant productivity and community composition in tropical forests. In lower montane tropical forests in western Panama, the distribution of understory palm species over a scale of 1-20 km correlates with differences in soil nitrogen (N). We hypothesized that soil N determines seedling performance in the forest understory, and, may therefore influence species distributions along the soil N gradient. 2. We explored the potential for N availability to generate species-habitat associations through species-specific differences in biomass allocation, photosynthetic capacity, N use-efficiency, and susceptibility to herbivory. Seedlings of nine palm species from two sub-families and four habitat types were transplanted into N-addition and control plots at a low N site. Growth, mortality, biomass allocation, photosynthesis, foliar N content and herbivory were measured over 21 months. 3. Foliar N increased for all species (15-68%) following N addition. Most species showed strong (20-200%) increases in photosynthetic rates with N addition except two species with marginal decreases in photosynthetic rates (5-15%). However, shifts in physiological traits did not increase relative growth rate or change in biomass allocation for any species or N treatment combination. Rather, increased leaf quality contributed to greater levels of herbivory in species associated with soils of intermediate and high inorganic N availability. 4. Thus, potential increases in overall growth with N addition were masked by herbivory, resulting in no apparent growth response with increased N. We suggest that for understory palms, and potentially other montane forest plants, distribution patterns are driven by a combination of physiological and herbivore-mediated responses to soil nutrient availability
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