1,720,965 research outputs found
(Table 1) Os and Sr isotopes in low-temperature hydrothermal fluids from the Juan de Fuca Ridge at ODP Site 168-1026B
No full textWe present Os and Sr isotopes and Mg, Os, and Sr concentrations for ridge-crest high-temperature and diffuse hydrothermal fluids, plume fluids and ridge-flank warm spring fluids from the Juan de Fuca Ridge. The data are used to evaluate the extent to which (1) the high- and low-temperature hydrothermal alteration of mid-ocean ridge basalts (MORBs) provides Os to the deep oceans, and (2) hydrothermal contributions of non-radiogenic Os and Sr to the oceans are coupled. The Os and Sr isotopic ratios of the high-temperature fluids (265-353°C) are dominated by basalts (187Os/188Os = 0.2; 87Sr/86Sr = 0.704) but the concentrations of these elements are buffered approximately at their seawater values. The 187Os/188Os of the hydrothermal plume fluids collected ~1 m above the orifice of Hulk vent is close to the seawater value (=1.05). The low-temperature diffuse fluids (10-40°C) associated with ridge-crest high-temperature hydrothermal systems on average have [Os] = 31 fmol/kg, 187Os/188Os = 0.9 and [Sr] = 86 µmol/kg, 87Sr/86Sr = 0.709. They appear to result from mixing of a high-temperature fluid and a seawater component. The ridge-flank warm spring fluids (10-62°C) on average yield [Os] = 22 fmol/kg, 187Os/188Os = 0.8 and [Sr] = 115 µmol/kg, 87Sr/86Sr = 0.708. The data are consistent with isotopic exchange of Os and Sr between basalt and circulating seawater during low-temperature hydrothermal alteration. The average Sr concentration in these fluids appears to be similar to seawater and consistent with previous studies. In comparison, the average Os concentration is less than seawater by more than a factor of two. If these data are representative they indicate that low-temperature alteration of MORB does not provide adequate non-radiogenic Os and that another source of mantle Os to the oceans must be investigated. At present, the magnitude of non-radiogenic Sr contribution via low-temperature seawater alteration is not well constrained. If non-radiogenic Sr to the oceans is predominantly from the alteration of MORB, our data suggest that there must be a different source of non-radiogenic Os and that the Os and Sr isotope systems in the oceans are decoupled
sj-docx-1-eso-10.1177_23969873221139410 – Supplemental material for Prolonged cardiac monitoring for stroke prevention: A systematic review and meta-analysis of randomized-controlled clinical trials
No full textSupplemental material, sj-docx-1-eso-10.1177_23969873221139410 for Prolonged cardiac monitoring for stroke prevention: A systematic review and meta-analysis of randomized-controlled clinical trials by Georgios Tsivgoulis, Lina Palaiodimou, Sokratis Triantafyllou, Martin Köhrmann, Polychronis Dilaveris, Konstantinos Tsioufis, Gkikas Magiorkinis, Christos Krogias, Peter D Schellinger, Valeria Caso, Maurizio Paciaroni, Mukul Sharma, Robin Lemmens, David J Gladstone, Tommaso Sanna, Rolf Wachter, Gerasimos Filippatos and Aristeidis H Katsanos in European Stroke Journal</p
High Precision and High Sensitivity Measurements of Osmium in Seawater
No full textWe present improved chemical separation and mass spectrometric procedures that permit precise and accurate determination of Os concentration and isotopic composition in seawater samples. Water samples (50 mL) with added 190Os tracer are heated to 300 °C at 128 bar in quartz carius tubes with CrVIO3. This allows tracer−sample equilibration via complete oxidation of all Os species to OsO4, which is then separated and purified using distillation. Samples are measured using negative thermal ionization mass spectrometry. A new loading technique using face-to-face double-filament geometry is developed that reduces organic interference and improves effective ionization efficiency, which is about 5% for 200 fg of Os (1 fg of Os = 3 × 106 atoms). The total yield of the chemical procedure is ∼90%, and the total procedural blank is 3.6 fg. We applied the new procedure on seawater depth profiles from the Atlantic, Pacific, and Southern Oceans and found that (1) the improved procedure results in an increase in Os concentration of 25−35% over previous methods, (2) Os in seawater does not appear to behave conservatively, and (3) surface seawater has lower 187Os/188Os values than deep waters
sj-pdf-1-wso-10.1177_17474930211058012 - Supplemental material for Rivaroxaban versus aspirin for prevention of covert brain infarcts in patients with embolic stroke of undetermined source: NAVIGATE ESUS MRI substudy
No full textSupplemental material, sj-pdf-1-wso-10.1177_17474930211058012 for Rivaroxaban versus aspirin for prevention of covert brain infarcts in patients with embolic stroke of undetermined source: NAVIGATE ESUS MRI substudy by Mukul Sharma, Eric E Smith, Lesly A Pearce, Kanjana S Perera, Scott E Kasner, Byung-Woo Yoon, Sebastian F Ameriso, Josep Puig, Dorte Damgaard, Jochen B Fiebach, Keith W Muir, Roland C Veltkamp, Roland C Veltkamp, Danilo S Toni, Nikolay Shamalov, Rubens J Gagliardi, Robert Mikulik, Stefan T Engelter, Daniel Bereczki, Martin J O’Donnell, Feryal Saad, Ashkan Shoamanesh, Scott D Berkowitz, Hardi Mundl, Robert G Hart and On behalf of the NAVIGATE ESUS MRI Substudy Investigators in International Journal of Stroke</p
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
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