1,721,224 research outputs found
Deep Atlantic Ocean 14C for 21 and 42 kcal BP according to simulations using INTCAL20
No full textRadiocarbon distributions in the past deep Atlantic ocean at 21,000 cal BP (around the Last Glacial Maximum, file = MRA_21000_calBP_30W.nc) and 42,000 cal BP (the onset of the Laschamps Geomagnetic Excursion, file = MRA_42000_calBP_30W.nc) according to simulations running from 55,000 cal BP to 0 cal BP carried out with the LSG ocean general circulation model (Butzin et al., 2020) forced with IntCal20 atmospheric Δ14C and ice core CO2. Each data set displays the median of nine simulation results. Shown is the depletion of dissolved 14C with respect to the contemporaneous atmosphere expressed in terms of 14C age. Low 14C concentrations translate to high 14C ages and vice versa. In both data sets the average ocean circulation is the same. The differences between 21,000 cal BP and 42,000 cal BP are rather due to changes in atmospheric Δ14C levels, and different leads and lags between this atmospheric 14C and its oceanic uptake and dispersal. Data contain marine reservoir age (MRA) which is calculated out of oceanic and atmospheric D14C according to Eq 1 in Butzin et al (2017)
Marine radiocarbon reservoir ages simulated for IntCal20, link to model results in NetCDF format
No full textBeyond ~13.9 cal kBP, the IntCal19 radiocarbon calibration curve is based upon combining data across a range of different archives including corals and planktic foraminifera. In order to reliably incorporate such marine data into an atmospheric curve, we need to resolve these records into their constituent atmospheric signal and marine reservoir age. This dataset includes results of marine reservoir age simulations enabling this resolution, applying the LSG ocean general circulation model forced with various climatic background conditions and with atmospheric radiocarbon changes according to the Hulu Cave speleothem record. Simulation period is 54,000-10,700 cal BP, depth range is 0-50 m. Land values are flagged with -100. This dataset is an update of PANGAEA datasets doi:10.1594/PANGAEA.876733 and doi:10.1594/PANGAEA.775379
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
Carbon cycle simulations results and estimates of the 14C production rate over the last 55,000 years
No full textThis data set contains carbon cycle simulations results and estimates of the 14C production rate Q over the last 55,000 years, as well as some not yet online available supporting time series. Some data sets cover up to the last 100,000 years. They have been compiled here in order to improve how independent approaches of Q when used in carbon cycle model frameworks improve simulations of atmospheric Δ14C in comparison to reconstructions, e.g. from IntCal20.
In detail, the following is contained:
a) three reconstructions (data-based estimates) of the 14C production rate based on (1) cosmogenic radionuclides from ice cores; (2) geomagnetic field data and (3) a 10Be stack from marine sediment records;
b) deconvolved (model-based) estimates of the 14C production rate from two different models, the carbon cycle box model BICYCLE-SE (8 scenarios) and the LSG OGCM (3 scenarios), both externally forced with atmospheric Δ14C, e.g. from IntCal20;
c) model-internal simulated atmospheric Δ14 when the data-based estimates of have been applied to force the the BICYCLE-SE model (11 scenarios)
d) simulated atmospheric CO2 from the BICYCLE-SE model (1 scenario);
e) supporting data: (1) a smoothed version from Hulu Cave Δ14 as has been used within IntCal20 as prior to calculate the marine reservoir age of contributing marine records; (2) a corrected version of the stack of cosmogenic radionuclides from ice cores underlying our ice core based version of Q
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
Experimental data compilation, thermal tolerance and thermal responsiveness of fish species and life stages
No full textThe data files contain experimental measurements of thermal tolerance, as well as temperature-dependent development and oxygen consumption rates (i.e. thermal responsiveness) of different life stages of fish. The data were extracted from studies published between 1930 and March 2020, including marine and freshwater species from all continents and climate zones (-70° to 80° latitude). The data were analyzed to assess differences in thermal tolerance and thermal responsiveness between life stages and species living at different latitudes. A phylogenetic imputation procedure was used to predict thermal tolerance limits of life stages for which no experimental data was available. Experimental and imputed thermal tolerance data were used to estimate thermal safety margins (indicating the risk of habitat loss) of different life stages of more than 600 species under different climate change scenarios by 2100
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