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Raw data of Cenozoic coccolith Feret's diameter from the Atlantic Ocean
No full textThis dataset contains the size measurement (μm) for each individual coccolith analysed in the sample for the Atlantic Ocean Sites DSDP 80-548 and ODP 154-925 and 154-929, spanning the Cenozoic (~0 to 66 Ma). Coccolith size data were acquired from images taken using an ImageStream X MkII flow cytometer with a light polarising filter and include circular-to-oval shaped coccoliths and star-shaped coccoliths. This dataset can be used to investigate how coccolith size of the aforementioned types changes through the Cenozoic
Cenozoic assemblage coccolith size (90th percentile of the Feret's diameter) from the Atlantic Ocean
No full textThis dataset includes the 90th percentile of the size of coccoliths in the assemblage (Feret's diameter; μm) for the Atlantic Ocean Sites DSDP 80-548 and ODP 154-925 and 154-929, spanning the Cenozoic (~0 to 66 Ma). Coccolith size data were acquired from images taken using an ImageStream X MkII flow cytometer with a light polarising filter and include circular-to-oval shaped coccoliths and star-shaped coccoliths. This dataset can be used to investigate how coccolith size of the aforementioned types changes through the Cenozoic
Impacts of the Early Eocene Climatic Optimum (EECO, ∼53‐49 Ma) on Planktic Foraminiferal Resilience
No full textThe Early Eocene Climatic Optimum (EECO; ∼53 and 49 Ma) records the warmest long‐term global average temperature and highest CO2 levels of the Cenozoic. Multiple transient global warming events occur within the EECO, offering an opportunity to investigate the impact of extreme heat on planktic foraminifera. Pacific Ocean Drilling Program (ODP) Sites 1209–1210 (Shatsky Rise) provide an excellent age model and stable isotope records to link biotic data with the carbon cycle across the interval here analyzed (55.6 and 49.93 Ma). We combine carbonate production proxies with changes in planktic foraminiferal assemblages and test‐size. Our data show that during the EECO planktic foraminiferal assemblages were permanently modified, besides transient changes. At the EECO onset, abundance of the genera Morozovella and Chiloguembelina decreased at 53.28 and 52.85 Ma, respectively, confirming published Atlantic Ocean data and thus the global decline of these genera. Given the dominance and large size of Morozovella in early Eocene tropical assemblages, we postulated that this change would have reduced foraminiferal production and the
assemblage test‐size. In contrast, we record a slight increase in test‐size within assemblages, controlled by the now dominant genus, Acarinina. The decrease in coarse fraction weight, partially controlled by dissolution, during times of stable foraminferal mass accumulation rate indicates enhanced calcareous nannofossil productivity reducing the foraminiferal contribution to the sediment. During the EECO, despite the decrease in abundance of some genera, species replacement within communities highlights the resilience of pelagic carbonate production, emphasizing the critical role of planktic foraminifera in regulating the marine food web
and global carbon cycling
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Planktic foraminiferal abundance and test-size record across the Early Eocene Climatic Optimum (EECO, ~53- 49 Ma) at Shatsky Rise (Pacific Ocean)
No full textThe dynamic early Paleogene climate presents the crucial opportunity to detect relationships among calcareous
plankton productivity, past carbon cycle perturbations and climate. We focus on the Early Eocene Climatic Optimum
(EECO, ~53-49 Ma) as it is associated with peak temperature and pCO2 of the Cenozoic and therefore offers a longterm
perspective of global warming impacts on marine biota. We investigate the Pacific sites 1209-1210, complementing
evidence that the EECO markedly impacted planktic foraminiferal assemblages at the Atlantic Oceans. The selected
sites have an excellent age model and stable isotope constraints that document the carbon isotope excursions that are the
expression of the several hyperthermals events superimposed on the long-term warming. We record an abrupt and
permanent abundance decline of more than one-third for the symbiont-bearing genus, Morozovella, from the beginning
of the EECO (J event, ~53 Ma) at sites 1209-1210, whereas Acarinina concomitantly increased in agreement with
Atlantic sites. One possible cause of the morozovellid abundance decline is a negative impact on their photosymbiotic
relationships with algae, as suggested by the lower 13C values exhibited by survivors. Symbiosis is advantageous in the
oligotrophic mixed-layer habitat and increases growth and final size. Therefore, we hypothesise that the morozovellid
decline may have reduced planktic foraminiferal productivity and test-size. We evaluated the Coarse Accumulation Rate
(CFAR) as an approximation of the planktic foraminiferal accumulation rate. The >38 m dominantly consists of
planktic foraminifera in pelagic sediments and here is not significantly affected by dissolution which would reduce
CFAR. In addition, we perform a test-size analysis on planktic foraminiferal assemblages across the EECO. Changes in
the size of marine calcifiers can be caused by evolutionary mechanisms or environmental perturbance, both of which
represent potential consequences of extreme warmth. Earlier work has shown that morozovellids are generally larger
than acarininids, hence suggesting that size should decrease when morozovellid abundance drops. Samples were split
into aliquots of 1000–1500 specimens and imaged at 160x magnification. The morphological parameters were analysed
in Olympus Stream Motion, and the 95th percentile of the maximum diameter was calculated. Unexpectedly, our results
show that the planktic foraminiferal assemblages do not display test-size reduction. Overimposed to a long-term general
test size increase trend, we recorded test-size fluctuations across the short-term hyperthermals. The increase of planktic
foraminiferal sizes across the hyperthermals may be linked to increases in the abundance of acarininids and decreases of
morozovellids, which is the common pattern across these events. CFAR decreases across the EECO during the
morozovellid abundance reduction, suggesting that this decline impacted overall planktic foraminiferal productivity and
was seemingly not balanced by the acarininids. Future test-size analysis of the two groups involved will help to unravel
a more exhaustive response to the EECO perturbance of planktic foraminiferal assemblag
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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