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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
The role of local earthworms in plant nutrient addition in the Ethiopian Drylands
No full textABSTRACT The Ethiopian Drylands are rich in their variety of local earthworm species. However, the category of species, and the effect of their performance on additions to plant nutrients have not been adequately evaluated. Thus, local earthworm samples were collected from the three major agroecological zones (highland, midland, and lowland) in Tigray (northern Ethiopia) and classified down to species level. Moreover, a vermicomposting experiment with four treatments (three local earthworm species, Eisenia fetida , and a conventional composting method) and three replications was established. Finally, each bin’s mature compost sample was taken to analyze plant nutrient content. The study results indicated that earthworm species in the highland, midland and lowland agroecological zones were Dendrobaena veneta, Eisenia andrie and Lumbricus rubellus , respectively. The use of these earthworms in the composting process (average of the four earthworm species) yielded higher nutrient content, ranging from 21.9 % for Sodium to 3300 % for Boron, compared to the conventional one. The highest total nitrogen (an increase of 44.4 %) and organic carbon (an increase of 33.4 %) were recorded in the Eisenia fetida and Dendrobaena veneta treated bins, respectively. Composting with Eisenia andrie has resulted in increases in P (96.1 %), K (125 %), Mg (83 %) and all micro-nutrients (between 91 % for Zn and 4400 % for B). Both Eisenia andrie and Lumbricus rubellus species contributed to the increased additions of Sulfur (85.7 %) compared to the control. It can be concluded that the use of local earthworms (particularly Eisenia andrie) in the composting process plays a significant role in plant nutrient addition.</div
Detectie en analyse van veranderingen in landgebruik en bodembedekking in Tigray, Noord-Ethiopië.
No full textSummaryMany parts of the world are suffering from environmental problems such as deforestation. Many papers described the causes and consequences of deforestation but very little information is available on mechanisms and effective policy measures that slow down deforestation rates. The motivation behind this PhD-research research was the hope that a better understanding of the mechanisms would help policy makers take the appropriate actions to stimulate forest transitions. The northern Ethiopian highlands were selected as a case study because evidence was available that at least in some local, possibly isolated cases, regreening was observed during the last decades. This research addressed 3 main questions: (1) what are the regional trends of land use and land cover change that took place in the northern Ethiopian highlands? (2) Can the observed land use and land cover change be linked with socio-economic, demographic, political or environmental factors? (3) Is it possible to outline optimal land use patterns that minimize future land degradation and maximize production and profitability?Detection of differential greening is, therefore, premeditated under chapter 2. This chapter presents a methodology to evaluate land cover changes on the basis of NDVI time-series derived from NOAA_AVHRR and SPOT vegetation sensors. The results show that the aggregated greenness in Tigray has declined between 1982 and 2010. On the basis of interpolated rainfall data, it was tried to disentangle the effect of fluctuations in preceding rainfall and human impact on the landscape greening. From 2000 onwards the degreening trend was slowed down and in some cases even reversed, which could partially be attributed to land abandonment on completely degraded land and the relative success of soil conservation measures.To evaluate the link between observed land use and land cover change and the socio-economic, demographic, political or environmental factors, a detailed study was carried out in 5 rural villages (chapter 3) and the Dessaa forest (chapter 4) for 3 different time-frames: 1965, 1994 and 2007. The maps were based on the interpretation of aerial photographs and high-resolution satellite imagery in combination with field validation. The results from rural villages showed a strong decrease of the forest and bush land in favor of arable land and rangeland from 1965 till 1994. This trend was, however, slowed down and even reversed from 1994 onwards whereby some of the arable land and rangeland is abandoned allowing shrubs and bushes to regenerate. However, household interviews and census data showed that the rural population number was still increasing while the productivity of the farming activities did not show a significant increase. The observed abandonment of marginal farm and rangeland was, therefore, only made possible through food aid and the import of food from other regions. The results from the Dessaa forest also showed that the forest cover of the area has decreased. While the area ofarable land and built-up surfaces have increased during these years. Population pressure was the most influential factor for the decline in forest cover in the study villages. Distance to built-up surfaces, distance to main roads and rivers, variation in slope, elevation and aspect were significant variables on forest degradation on major part of the study area. Changes in forest policies, have also contributed to the decline in forest cover. The extent to which land use patterns can be optimized to minimize further land degradation and to maximize the incomes generated from farming was examined (chapter 5) in the catchment of the Geba River. An ordinal classification of soil erosion rates and profitability assessments were put in a spatial decision support system in order to generate optimal land use patterns. The profit maximisation scenario showed that in order to generate higher profits, the landscape must be organised in a sort of Von Thünen landscape with concentric rings surrounding the market places. The erosion minimization scenario showed that a concentration of all the arable land in the less erodible places would reduce the average soil erosion rate. The mixed scenarios in which reduction of erosion and increase of profitability were both taken into account showed that the definition of the weights of the performance indicators is of crucial importance. If the generation of total profits is emphasized, the corresponding land use pattern would consist of even more arable land than the present day situation. If soil conservation received more weight the optimal landscape would consist of less arable land but with a higher area-specific profitability.status: Publishe
Evaluation of land suitability for selected tree species in the Mesozoic Highlands of Ethiopia
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