1,720,955 research outputs found
Comparing GPR with ice thickness and thermal models: insights from two polythermal glaciers in West Greenland
No full textThis work aims to address two main scientific objectives. First, it seeks to rigorously compare ice thickness estimates from GPR datasets with those derived from various modelling approaches. Second, it examines warm and cold ice areas identified by GPR in relation to 2D thermal modelling performed along selected profiles. The analyses focus on two nearby glaciers in Greenland, surveyed in different years (2014 and 2024) and seasons (August and February) and with different GPR antennas, namely 50 MHz unshielded and 100 MHz shielded. We found that global-scale ice thickness models provide relatively accurate volume estimates at regional scale, while they have limitations in local accuracy, as well as the ice thickness models, especially when the bedrock topography derived from GPR data is complex. 2D thermal modelling results were only partially consistent with warm and cold ice occurrence derived from GPR data, indicating the unique and complex thermal structures of polythermal glaciers with irregular shape and geometry. Due to the differences between the two surveys, we believe that the results are relevant not only to the specific test site, but to a wider range of geographical and climatic conditions and may provide useful guidance for similar applications
Long-term mass-balance monitoring and evolution of ice in caves through structure from motion–multi-view stereo and ground-penetrating radar techniques
No full textThis study investigates the application of a terrestrial structure from motionmulti-view stereo (SfM-MVS)
approach combinedwith ground-penetrating radar (GPR) surveys formonitoring the surface topographic change
of two permanent ice deposits in caves located in the Julian Alps (south-eastern European Alps). This method
allows accurate calculation of both seasonal and annual mass balance, estimating the amount of ice inside caves.
The ground-based SfM approach represents a low-cost workflow with very limited logistical problems of
transportation and human resources and a fast acquisition time, all key factors in such extreme environments.
Under optimal conditions, SfM-MVS allows sub-centimetric resolution results, comparable to more expensive
and logistically demanding surveys such as terrestrial laser scanning (TLS). Fourteen SfM acquisitions were made
between the 2017–2020 ablation seasons (i.e. July–October) while 2 GPR surveys were acquired in 2012. The
obtained dense point clouds and digital terrain models (DTMs) made possible a reliable calculation of topographic
changes and mass balance rates during the analysed period. The integration of SfM-MVS products with GPR
surveys provided comprehensive imaging of the ice thickness and the total ice volume present in each of the
caves, proving to be a reliable, low cost and multipurpose methodology ideal for long-term monitoring
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
A glacier in transition: Surface elevation change, ELA and geomorphic evolution of a very small glacier in the Dolomites (S-E Alps)
No full textSmall glaciers of temperate mountain regions are suffering significant reduction, with ice mass losses reaching unprecedented melt rates in the very last years. On the other hand, several glacial bodies experienced increasing debris inputs since the end of the Little Ice Age, transitioning from rather clean ice to debris-covered and, sometimes, to rock glaciers. Here we present the recent surface elevation change (2006–2022) of the Popera Alto glacier, a very small debris-covered glacier in the Sesto Dolomites (S-E European Alps), retrieved from a combination of airborne LiDAR and Structure from Motion surveys. We analyse the glacier evolution in terms of surface cover and geomorphic processes, reconstructing its palaeo-volume and -extent from geomorphological evidence. The environmental Equilibrium Line Altitude (envELA) based on climatic data is compared to the effective ELA (effELA), discussing the role of local topography in the evolution of small debris-covered glaciers. Popera Alto glacier lost 0.35 m w.e. yr−1 in the last 16 years, with its surface cover actively modified by geomorphic processes. Debris and local topography feedback allowed the resilience of the glacier, with marked difference between the current envELA of the area, 3480 m a.s.l., and the effELA of the glacier, 2550 m a.s.l. As such, Popera Alto glacier shows evidence of transitioning from a glacial to a periglacial landform
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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