1,721,513 research outputs found
Personal -- 1939-41 -- Correspondence, Miscellaneous -- letter, 1941-06-18
No full textLetter from Snyder, R. Garfield to Sabin, Albert B. dated 1941-06-18.Sabin Collection Fair Use Policy</a
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
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
Important factors to model climate change effects on evapotranspiration
No full textAbstract
Although growers have considerable control over crop production, a major concern is the anticipated increase in evapotranspiration (ET) due to global warming. ET rates, however, are also affected by radiation, humidity, wind speed, crop morphology, and crop physiology in addition to temperature. Crop ET (ETc) is commonly estimated as the product of reference ET (ETo) and a crop coefficient (Kc), and the main factors affecting Kc values are net radiation, aerodynamic resistance, and canopy resistance differences between the reference and crop surfaces. The standardized ETo equation has fixed values for the canopy resistance (rc), and different values are likely for other crops. The rc values might also adjust with increasing CO2 and higher temperature. Aerodynamic resistance (ra) depends on atmospheric stability, wind speed, and surface roughness. The relative aerodynamic contributions of sensible heat to ETo and ETc could change if the canopy development or the wind speed climatology are modified by global warming. In this paper, we will discuss how the ETo and Kc values vary with microclimate and how Kc values and ETo rates might react to global warming. © 2008, Page Press Publications. All rights reserved
Crop Coefficients: A Literature Review
No full textRecently presented climate change scenarios include increasing demand for water, due to both increase in temperature and variations in precipitation pattern. Since crop water requirements are related to climate and irrigation scheduling depends on crop evapotranspiration (ETc), it is crucial to have tools that allow the estimation of ETc in a reliable way. ETc is often calculated as the product of two factors, the reference evapotranspiration (ETo) and crop coefficient (Kc) values that convert ETo to ETc. This paper reviews Kc values, measured in different parts of the world and in different climates, with the aim to offer a practical tool for selecting the most appropriate Kc values for water balance irrigation scheduling, which result in more efficient irrigation. More than 100 scientific papers were studied and summarized in a report, accompanied by an extensive Kc database. The Kc report and database are available in the “Supplemental Data” section of this paper
The Extracted-Zero: A Practical Solution for Transmission Zeros in Wideband Filters
No full textThis letter presents a practical solution to realize finite frequency transmission zeros with independent location for wideband evanescent-mode filters. The method consists of using offline resonators located at the input and/or output of the filter. In contrast with the extracted-pole technique commonly employed for narrowband filters to generate a pole-zero pair, each offline resonator is used here in such a way so that the sole transmission zero is actively used in the filtering function. The latter characteristic is what makes this technique practical for wideband filters as it prevents the presence of unfeasibly strong coupling coefficients, as well as avoiding impractical nonresonating node elements. The offline resonator, which we named extracted-zero, can be coupled to the first or last resonator of a wideband bandpass filter, and it is conveniently realized using the same technology as any other resonator of the filter. The extracted-zero can be seen as a first-order notch filter which is directly embedded into the bandpass filter (instead of being cascaded afterward). The feasibility of this solution is validated by the experimental results of a challenging 225-450-MHz bandpass filter (66.6% fractional bandwidth) which employs 17 inline resonators plus 2 extracted-zeros so as to obtain 50 dB rejection below 195 MHz
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