1,720,996 research outputs found
Visible and Infrared Spectroscopical Applications
No full textSpectra in the visible (VIS) and infrared (IR) region contain a wide variety of information about inorganic and organic substances in sediments. The information from the spectra enables a wide array of applications that allow quantitative, semiquantitative, and qualitative characterization of sediment. Due to the fact that instrument/experimental setups are simple, rapid, and cost-saving and that only small sample quantities are required, the technique has become valuable in paleolimnological and Quaternary science. This article summarizes the theoretical background of VIS and IR spectroscopy, explains the analytical process, introduces statistical tools used for interpretation of spectra, and provides examples of applications in Quaternary science
Visible and infrared spectroscopical applications in paleoenvironmental research
No full textSpectra in the visible (VIS) and infrared (IR) region contain a wide variety of information about inorganic and organic substances in sediments. The information from the spectra enables a wide array of applications that allow quantitative, semiquantitative, and qualitative characterization of sediment. Due to the fact that instrument/experimental setups are simple, rapid, and cost-saving and that only small sample quantities are required, the technique has become valuable in paleolimnological and Quaternary science. This article summarizes the theoretical background of VIS and IR spectroscopy, explains the analytical process, introduces statistical tools used for interpretation of spectra, and provides examples of applications in Quaternary science
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
Potential analogues for paleoclimatic variations in eastern interior Alaska during the past 14,000 yr: atmospheric-circulation controls of regional temperature and moisture responses
No full textThe paleoclimatic history of a region can be viewed as a series of surface temperature and moisture anomalies through time. The effects of changes in large-scale climatic controls (e.g., insolation, major circulation controls) can be mediated by the influence of smaller-scale controls (e.g., topographic barriers, coastlines); this may result in heterogenous surface climatic responses at the regional and sub-regional scale. Divergent paleoclimatic trajectories between regions may be explainable in terms of such meso-scale patterns. Using modern analogues for paleoclimate we examine how the sequence of climatic variations in eastern interior Alaska during the interval 12,000–0 14C yr BP could have been generated by specific atmospheric circulation patterns. Fossil-pollen and lake-level records document the long-term trends in temperature and effective moisture for the region. Water-balance modelling provides additional estimates of paleoprecipitation. Synoptic climatological patterns are described using the modern (instrumental) record of upper-level and sea-level pressure, surface temperature, and precipitation. At 12,000 14C yr BP, eastern interior Alaska was cooler and drier than present, a situation generated today by a southward displacement of the jet stream. Conditions warmer and drier than present at 9000 14C yr BP may have been generated by increased ridging north of Alaska and a weakened westerly circulation. Warmer, wetter conditions than present possibly prevailed in the late-middle Holocene; these might reflect ridging over Alaska and troughing further west. Cool, wet conditions feature enhanced westerly flow into Alaska through an eastward shift in the east Asian trough and positive pressure anomalies in the North Pacific; they may be analogous to cold periods of the Little Ice Age. The analogues demonstrate how surface conditions in other parts of Beringia may sometimes be similar to, while at other times different from those in the eastern interior. These broader spatial patterns provide hypotheses about past climates that can be tested with paleoclimatological data. For example, the widespread positive temperature anomalies associated with the warm/dry (9000 14C yr BP) analogue fit with the expansion northward of the eastern Siberian treeline. The anomalously cool conditions in northeast Siberia associated with the warm/wet analogue may explain the continued (late-middle Holocene) treeline advance in Alaska while there was retreat in Siberia
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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