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Multi-proxy Holocene palaeoclimate records from Walton Moss, northern England and Dosenmoor, northern Germany, assessed using three statistical approaches
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Oxygen-isotope variability across the 8.2 ka cold event in an ombrotrophic peat bog on the Bonavista Peninsula, Newfoundland
No full textEvidence of the severity of the 8.2ka cold event from an ombrotrophic peat bog in Newfoundland
No full textHolocene climate variability revealed by oxygen isotope analysis of Sphagnum cellulose from Walton Moss, northern England
No full textStable isotope analyses of Sphagnum alpha-cellulose, precipitation and bog water from three sites across northwestern Europe (Raheenmore, Ireland, Walton Moss, northern England and Dosenmoor, northern Germany) over a total period of 26 months were used to investigate the nature of the climatic signal recorded by Sphagnum moss. The ?18O values of modern alpha-cellulose tracked precipitation more closely than bog water, with a mean isotopic fractionation factor ?cellulose-precipitation of 1.0274 ± 0.001 (1?) (?27‰). Sub-samples of isolated Sphagnum alpha-cellulose were subsequently analysed from core WLM22, Walton Moss, northern England yielding a Sphagnum-specific isotope record spanning the last 4300 years. The palaeo-record, calibrated using the modern data, provides evidence for large amplitude variations in the estimated oxygen isotope composition of precipitation during the mid- to late Holocene. Estimates of palaeotemperature change derived from statistical relationships between modern surface air temperatures and ?18Oprecipitation values for the British Isles give unrealistically large variation in comparison to proxies from other archives. We conclude that use of such relationships to calibrate mid-latitude palaeo-data must be undertaken with caution. The ?18O record from Sphagnum cellulose was highly correlated with a palaeoecologically-derived index of bog surface wetness (BSW), suggesting a common climatic driver.<br/
Terrestrial climate signal of the "8200-yr cold event" in the Labrador Sea region
No full textAccelerated melting of Greenland ice has raised concern about the future impact of enhanced freshwater discharge on regional climate through its effect on ocean circulation. An abrupt cooling event ca. 8200 cal. yr B.P. has been linked to meltwater from the decaying North American ice sheet. Oxygen isotopic analyses of cellulose from subfossil Sphagnum mosses, isolated from a Newfoundland peat core, reveal a pronounced anomaly ca. 8350 yr B.P. with a duration of ~150 years. The maximum estimated ?18Oprecipitation change, 4.53‰ ± 1.05‰ (Vienna Standard Mean Ocean Water), is the largest observed in the circum-North Atlantic region. The magnitude of change exceeds that predicted by recent paleoclimate simulations. Comparisons with recent records of surface and deep ocean proxies in the Labrador Sea and the wider North Atlantic region suggest synchroneity. However, an ~200 year delay between the responses of the Labrador Sea region and the Greenland Ice Sheet to the effects of meltwater release remains to be explained
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
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
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