1,721,109 research outputs found
Age model, d18O, declination, inclination, MAD and RPI from ODP Site 172-1063, Bermuda Rise
No full textAn age model for the Brunhes Chron for Ocean Drilling Program (ODP) Site 1063 (Bermuda Rise) is based on the tandem correlation of oxygen isotope (from G. ruber) and relative paleointensity data to calibrated reference templates. Four intervals in the Brunhes Chron where component inclinations are negative for both u-channel samples and discrete samples are correlated to the following magnetic excursions with Site 1063 ages in brackets: Laschamp (41 ka), Blake (116 ka), Iceland Basin (190 ka), Pringle Falls (239 ka). These ages are consistent with current age estimates for these excursions, other than for "Pringle Falls" which has an apparent age older than a current estimate by ~20-30 kyrs. For each of these excursions (termed Category 1 excursions), virtual geomagnetic poles (VGPs) reach high southerly latitudes implying paired polarity reversals of the Earth's main dipole in a brief time span (<2 kyr in each case) that is several times shorter than the observed duration of long-lived polarity transitions. Several intervals of low component inclinations, that are low and negative in one case, are observed both in u-channel and discrete samples at ~318 ka (MIS 9), ~412 ka (MIS 11) and in the 500-600 ka interval (MIS 14-15). These Category 2 excursions may constitute inadequately recorded excursions, or high amplitude secular variation
Surface and deep-water hydrography on Gardar Drift (Iceland Basin) during the last interglacial period
No full textChanges in surface and deep-water hydrography were inferred from variations in stable isotopes and sortable silt mean grain size, respectively, on the southern Gardar Drift in the subpolar North Atlantic. The bathymetric ?13C gradient during the penultimate glaciation was similar to the last glaciation with high- ?13C Glacial North Atlantic Intermediate water above ? 2000 m, and low- ?13C water derived from the Southern Ocean below. During Termination II, low-?13C water was present throughout the water column with minimum values at intermediate depths (? 1500–2000 m) and below 3000 m. This pattern continued well into the early part of the Last Interglacial (LIG) period. Sortable silt mean size at 3275 m suggests that deep-water circulation on Gardar Drift was relatively weak during the earliest part of the LIG (128 to 124.5 ka) when planktonic ?18O was at a minimum, reflecting warming and/or reduced salinity. We suggest that low- ?13C water and slow current speed on Gardar Drift during the early part of the LIG was related to increased melt water fluxes to the Nordic Seas during peak boreal summer insolation, which decreased the flux and/or density of overflow to the North Atlantic. The resumption of the typical interglacial pattern of strong, well-ventilated Iceland Scotland Overflow Water was delayed until ? 124 ka. These changes may have affected Atlantic Meridional Overturning Circulation
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
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