1,721,309 research outputs found
Phenology and dynamics of an African rain forest at Korup, Cameroon
No full textIn groves of ectomycorrhizal caesalpinaceous legumes in Korup, Cameroon, the most abundant of three co-dominant tree species, Microberlinia bisulcata, has had, and continues to show, very low recruitment. Replacement is likely to favour the two other guild members, Tetraberlinia bifoliolata nod T. morelitma. All three species produce large sufficient seedling banks.
Microberlinia bisulcata attained the greatest tree sizes and had the most pronounced mast fruiting pattern (a 3-year cycle). Masting was associated with peaks in the previous dry-season radiation suggesting a requirement to accumulate carbon reserves before fruiting. More circumstantial evidence points to phosphorus supply as a co-controlling factor.
The dominance of M. bisulcata is most likely due to a recently unique, natural historical event, an epoch of unusually dry years, which allowed its shade-intolerant ectomycorrhizal seedlings to outcompete other species. The putative fungal connections to parents appear to be of no advantage (possibly a disadvantage) to the seedlings under such mature adults.
The composition of Korup is neither constant nor cycling but a fragment of change which might be reset by climatic fluctuations coincident with potential regeneration of a species also adapted to the low-phosphorus soils and strongly seasonal conditions of the site. Understanding the dynamic& of such an African forest requires a stochastic view over several centuries
Englerodendron korupense (Fabaceae, caesalpinioideae), a new tree species from Korup National Park, Cameroon
No full textFIG. 2. — Englerodendron korupense Burgt: A, inflorescense; B, fruits; C, seedlings; D, stem base of the tree from which the type was collected. A, van der Burgt 741; B, van der Burgt 760; C, van der Burgt & Eyakwe 711.Published as part of Van Der Burgt, Xander M., Eyakwe, Moses Bisongi & Newbery, David M., 2007, Englerodendron korupense (Fabaceae, Caesalpinioideae), a new tree species from Korup National Park, Cameroon, pp. 59-65 in Adansonia (3) 29 (1) on page 63, DOI: 10.5281/zenodo.460185
Optimal tariffs on exhaustible resources
No full textWe characterize the Markov perfect equilibria of two games in which oligopsonistic importers of an exhaustible resource confront competitive suppliers who have rational expectations. The games differ only in the timing of moves, or the speed with which participants can adjust their plans. The optimal tariff when sellers move first (are less flexible) differs considerably from that in which buyers move first, and sellers retain more control over intertemporal arbitrage opportunities. If the initial stock is small, buyers suffer a disadvantage from being the first-mover; this is reversed if the stock is large
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
Gluema korupensis (Sapotaceae), a new tree species from Korup National Park, Cameroon
No full textGluema korupensis Burgt (Sapotaceae), a new species from the southern part of Korup National Park in Cameroon, is described and illustrated. In total 176 trees 2 25 cm in stem diam. were found. The tree from which the holotype was collected was 42 m high and 125 cm in diam.; the largest tree was 238 cm in diam. The seeds are dispersed ballistically and sometimes by wate
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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