1,720,961 research outputs found
Opportunity costs of growing space – an essential driver of economical single-tree harvest decisions
No full textControlling the growing space available to trees is essential for silvicultural management. For an efficient, i.e. economical, allocation of the scarce growing space, a qualitative and quantitative knowledge of all drivers of harvest decisions is required. The fundamental Faustmann-Pressler-Ohlin-Theorem reveals these drivers at the stand level: In the economical optimum, the stand's future value increment is equal to the interest of its value plus the land rent of the following stand. However, with increasing availability of single-tree data and single-tree-oriented management of heterogeneous stands, the need to transfer these fundamental economic relationships to the single-tree level arises. While several studies already focus on this problem, approaches using practice-related growth and harvest simulations that omit assumptions on the optimal thinning type are still somewhat rare. Our study seeks to provide a deeper understanding of basic economic principles underlying single-tree harvests. We thus aim to contribute to the methodological improvement of decision support systems regarding the implementation of silvicultural-economic linkages. We present a simulation-optimization model to analyze the importance of opportunity costs of growing space for economical harvests of even-aged single-trees under varying production goals and individual tree characteristics. Here, we show that controlling the competition-based growing space efficiency should guide harvest decisions at a young age, whereas with age the focus should shift to possible investment alternatives for the financial resources fixed in a tree. Our analyses of economical harvest decisions indicate that the importance of individual tree characteristics rises with increasing heterogeneity. We found some surprising economically optimal harvest sequences in heterogeneous groups of trees, which underlines the high potential of our model to inform practical decision making at the single-tree level. By implementing economic theory in marteloscopes, our approach could enable an improved training of forest managers to face complex silvicultural decisions. In an environment shaped by scarcities, the derived principles can be applied to various ecosystem services
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
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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