1,720,988 research outputs found
Biotic and Abiotic Processes on Granite Weathering Landforms in cryotic environment, Northern Victoria Land, Antarctica
No full textA multidisciplinary study was carried out to understand the interactions between biotic and abiotic
processes in granite weathering in ice-free areas of northern Victoria Land, Antarctica. Examples of
tafoni, pits and grooves were analyzed, focusing on their morphometry, infills, weathering rind types
and vegetation patterns. Surface and subsurface temperatures and incoming radiation were measured
to characterize microclimatic conditions. In addition, microscopic, SEM and X-ray diffraction
analyses of granite were carried out. These analyses indicate that, under present conditions,
mechanical weathering is the main process active in the formation of tafoni, which post-date pits
and grooves. In these forms, granular disintegration is mainly induced by chasmoendolithic lichens,
salt and thermal stress associated with the dilatation coefficients of different granite-forming minerals.
The overall morphology of pits and grooves indicates that they originate from water erosion. In the
former, mechanical weathering prevails, caused by epilithic lichens, by freeze-thaw events, and by
salt, while only the first two processes are active in the grooves. The intensity of these processes is less
effective than in tafoni and on the outer surfaces, suggesting that pits and grooves are inherited
features, possibly generated in the same way as landforms occurring on granite in the humid tropics
Biotic and Abiotic Processes on Granite Weathering Landforms in a Cryotic Environment, Northern Victoria Land, Antarctica
No full textA multidisciplinary study was carried out to understand the interactions between biotic and abiotic processes in granite weathering in ice-free areas of Northern Victoria Land, Antarctica. Examples of tafoni, pits and grooves were analyzed, focusing on their morphometry, infills, weathering rind types and vegetation patterns. Surface and subsurface temperatures and incoming radiation were measured to characterize microclimatic conditions. In addition, microscopic, SEM and X-ray diffraction analyses of granite were carried out. These analyses indicate that, under present conditions, mechanical weathering is the main process active in the formation of tafoni, which post-date pits and grooves. In these forms, granular disintegration is mainly induced by chasmoendolithic lichens, salt and thermal stress associated with the dilatation coefficients of different granite-forming minerals. The overall morphology of pits and grooves indicates that they originate from water erosion. In the former, mechanical weathering prevails, caused by epilithic lichens, by freeze-thaw events, and by salt, while only the first two processes are active in the grooves. The intensity of these processes is less effective than in tafoni and on the outer surfaces, suggesting that pits and grooves are inherited features, possibly generated in the same way as landforms occurring on granite in the humid tropic
Vegetation colonization of permafrost‐related landslides,Ellesmere Island, Canadian High Arctic
Full text linkRelationships between vegetation colonization and landslide disturbance are analyzed for 12 active‐layer detachments of differing ages located in three areas of the Fosheim Peninsula, Ellesmere Island (80°N). We discuss vegetation as an age index for landslides
and a way to assess the time needed for complete recolonization of the surfaces since landslide detachment. Vegetation on undisturbed terrain is similar in the three areas but is more highly developed and complex inland due to a warmer summer climate. On a regional scale, the location of the area is as important as the effect of landslide age on vegetation colonization because of the influence of mesoclimatic conditions on vegetation development. On a landscape scale, there is a positive relationship between landslide age and vegetation development, as represented by total vegetation cover, floristic
composition, and successional stage. Consequently, vegetation can be used at this scale as an indicator of landslide age. Fifty years are required to restore vegetation patches to a floristic composition similar to communities occurring in undisturbed conditions, but with
lower floristic richness and a discontinuous cover and without well‐developed layering. The shorter time needed for landslide recovery in the area with the warmest summer climate confirms the sensitivity of arctic vegetation to small differences in air temperature. This could trigger a set of interlinked feedbacks that would amplify future rates of climate warming
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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