1,721,193 research outputs found
A PPP kinematic application on historical GPS data: the reprocessing of the ITASE98-99 Antarctica mission height profiles
Full text linkThe analysis of altimetric profiles in Antarctica and their evolution over the years is a sensitive topic for the scientific community since it helps understand the effects of climate change that the continent undergoes. Different geomatic techniques, including the GNSS technology, can be employed to obtain altimetric profiles. However, the GNSS differenced approaches, such as the Post Processing Kinematic, are hardly usable to define long profiles in Antarctica because of the low number of CORS stations. In these conditions, the Precise Point Positioning (PPP) approach is a valid alternative to avoid processing very long baselines. The aim of this article is to define a standard procedure for the processing of historical GPS data, thanks to the availability of a dataset from the International Trans-Antarctic Scientific Expedition, which took place between 1998 and 1999 (ITASE98-99). This expedition focused on mapping the Antarctic territory, subdividing it by nations of influence, using geophysical and geodetic technologies, including GPS. The altimetric profiles had already been calculated in 2002 by the Geomatics group of the University of Bologna using the Gipsy-OASIS II software. In this work, the new version of the JPL software, GipsyX, is used to apply the newly implemented models and reprocessed products. The calibration of the processing parameters leading to the final PPP solution is described in the paper, including details on the implementation of a post-processing filtering procedure. The average a posteriori elevation error is 4.6 cm, while 99% of them are within 27 cm. The comparison of the new results to both the previous processing and the REMA elevation model shown that about double the number of solutions are now available, meter-level elevation spikes have been avoided, and a half meter bias is now reduced to a few centimeters. Given the almost 15 years difference between the 1999.0 expedition epoch and the REMA reference epoch, the obtained results can be used to study accumulation/erosion effects on the Antarctica ice sheet
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Snow accumulation rates at Concordia Station, Antarctica, observed by stake farms
Full text linkIn this study, surface mass balance (SMB) is estimated from snow accumulation data collected in the nearby area of Concordia Station, Antarctica. Results from the Italian and French stake farms are jointly analysed. The Italian stake farm consists of 13 stakes; continuous observations started at the end of 2010 with near-monthly sampling. Some measurements are also available for the 2006-2010 period from a previous stake farm. The French stake farm consists of 50 stakes; observations started in 2004 with yearly sampling during austral summer. Snow buildup measurements at individual stakes show a strong variability caused by the interaction of wind-driven snow with surface micro-relief. In the common observation period, the present Italian stake farm generally underestimates the SMB with respect to the French one, except for three years in which an overestimation is observed. Over the 2011-2023 period, the mean yearly accumulation recorded by the Italian and French stake farms is 7.3±0.2 cm and 8.4±0.1 cm, respectively. Bootstrap simulation has been performed to: (i) assess the significance of the differences between the two datasets; (ii) evaluate the effect on the measurements of the different size of the stake farms and their distance to the Station. The comparison of the observations with reanalysis datasets (ERA5 and MERRA2) and regional models (RACMO2.4p1, MAR3.12) indicates the former more in agreement with the observations. The potential interaction effect of the Station has also been investigated by analysing wind direction during snowfall events, suggesting that buildings may influence accumulation In fact, in the hyper-arid environment of Dome C, snow accumulation is largely governed by post-depositional processes such as wind redistribution and clear-sky precipitation. Buildings alter the wind field, enhancing erosion beneath them and forming snowdrifts leeward and laterally, which may explain accumulation differences between the ITA and FRA stake fields.. Additionally, two more stake farms, located 25 km North and South of Concordia Station, are also analysed to study the SMB gradient across Dome C, confirming previous results. On average, yearly SMB increases northward by 8-9% over the 50 km span between the southern and northern stake farms. At Concordia, for the 2004-2023 period, a mean SMB of 27.21±0.60 kg m–2 has been estimated, taking into account the uncertainty of the observations and of the snow compaction effect. Results are valuable for validating SMB estimated from reanalysis, regional climate models and remote-sensing data
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