1,720,995 research outputs found
Ten years of oxygen and hydrogen isotopic composition of daily precipitation at Concordia station, East Antarctica
No full textHere we present a 10year
(20082017)
record of the isotopic composition of precipitation at
Dome C. The winterover
personnel at Concordia Station have been continuously collecting
daily precipitation since 2008: this represents a unique record of the isotopic composition of
precipitation from the Antarctic Plateau. Snow is collected on a raised platform (height: 1 m) in
the clean area of the station and analyzed for d18O, dD and deuterium excess. A significant positive
correlation between d18O (dD) of precipitation and 2m
air temperature is observed at different
temporal scale; the lowest temperature and isotopic values are preferentially observed
during winters affected by a strongly positive Southern Annular Mode index [Stenni et al., 2016].
We have compared the isotopic data of Concordia samples with meteorological data from the
Dome C AWS of the Programma Nazionale di Ricerche in Antartide (PNRA), as well as with the
isotopeenabled
atmospheric general circulation models ECHAM5wiso
and ECHAM6wiso,
in
order to improve the understanding of the mechanisms governing the isotopic composition of
precipitation on the Antarctic plateau, which are yet to be fully understood, as well as the postdepositional
effects altering the pristine isotopic signal of precipitation. The comprehension of
these physical processes is fundamental for reconstructing past temperature variations using
the isotopic records from ice cores drilled in low accumulation areas of Antarctica [Casado et
al., 2018], e.g., the upcoming Beyond EPICA drilling at Little Dome C. Very few temporal relationships
between temperature and snow isotopic composition, mostly limited in time or sampling
frequency, have been calculated, while spatial relationships have been traditionally used
to reconstruct past temperature from ice core isotopic records [MassonDelmotte
et al., 2008]
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
Monitoring the oxygen and hydrogen isotope composition of precipitation at Concordia Station, East Antarctica
Full text linkOxygen and hydrogen stable isotope records in ice cores are widely used for reconstructing past temperature variations. However, the relationship between δ18O (δ2H) of precipitation and air temperature is yet to be fully comprehended and fine-tuning the sensitivity of the paleothermometer is crucial to obtain accurate temperature reconstructions from ice cores.
Since 2008, daily precipitation is collected on raised surfaces in the clean area of Concordia Station on the East Antarctic plateau, as part of the WHETSTONE and AIR-FLOC PNRA projects. Each sample is analyzed for δ18O and δ2H, and deuterium excess is calculated.
Here we present the δ18O (and δ2H) record from 2008 to 2023: a 15-year continuous dataset that stands as the longest series of stable isotopes in daily precipitation ever recorded for Antarctica.
An extraordinary event captured within this dataset is the March 2022 heatwave, which brought unprecedented high temperatures to East Antarctica: this event left a distinct imprint on the isotopic composition of precipitation, leading to the highest δ18O (δ2H) values ever recorded in our dataset since 2008.
For selected samples from 2022 and 2023, δ17O was also analyzed, allowing us to calculate the 17O excess: this parameter provides additional information on the hydrological cycle processes and is particularly sensitive to kinetic fractionation during evaporation and condensation
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
Investigating Mercury (Hg) and Water Stable Isotopes Composition (δ18O and δ2H) in Bottled Waters: A survey Study in Italy
No full textIn the last years, several studies have been conducted on bottled waters (BW) at national, regional, and worldwide scale considering major and trace elements, organic compounds and/or emerging contaminants. Hitherto, a few studies focused on mercury, and water stable isotopes determination of bottled waters are available in the literature. Therefore, this kind of research on BW can periodically be useful for understanding the potential variation of these parameters over time. Italy is one of the main producers of BW and Italians are the greatest consumers of natural mineral waters per capita in the European Union. The natural mineral water sources (natural spring and groundwater) across Italy, are generally placed on flood plains or mountain slopes. European and national regulations established that BW must be microbiologically pure without any purification process because they originate from aquifers or underground reservoirs. Total mercury (Hg), stable isotopic composition (δ18O and δ2H) and additional physico-chemical parameters have been evaluated on selected bottled waters purchased in the Italian stores. Bottle samples from different Italian water catchments all over Italy are here characterized to be representative of different hydrogeological conditions. Numerous brands of BW representing different water typologies (still, sparkling, naturally sparkling, and slightly sparkling), bottled in different packaging, have been considered. Instrumental analyses (e.g.: CVAFS, Cavity Ring-Down Spectroscopy) were carried out in the laboratories of CNR and Ca’ Foscari University. The main objective of this work is to investigate the occurrence of Hg in Italian bottled waters considering δ18O, δ2H and deuterium excess, as well as the differences on physico-chemical parameters, (approx. ten years later, after the last national surveys) taking into account their wide representativeness of the geographical area and geological provenance
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