1,720,968 research outputs found
Activity and Osmotic Coefficients from the Emf of Liquid Membrane Cells. IX : Mn(ClO4)2 and MnSO4 in water at 25 °C
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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
System for signal to noise separation for electrochemical instruments.
No full textA device for separating a signal from noise and background contributions, particularly for computerized electrochemical instruments. It comprises an experimental data manipulator circuit; an ordering processor connected to the manipulator and arranged to provide the manipulator with the rules for the correct formatting of the experimental data, on the basis of selective operative modes; a command sequencer circuit, which governs the operation of the device on the basis of the values of the characteristic parameters for each mode; an interpolator circuit which executes the selective operative modes and recalculates each formatted data item using algorithms based on interpolation polynomials calculated by the Newton divided differences formula and the Aitken scheme for accelerating the calculation
Models of pesticides inside cavities of molecular dimensions. A role of the guest inclusion in the dechlorination process
No full textThe reduction mechanism of the pesticide vinclozoline (3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione) was studied in nonaqueous solvents in the confined environment of a cyclodextrin (CD) cavity. The effect of the cavity dimensions on the mechanism of the redox process was evaluated using glucose as a reference and using three cyclodextrin molecules of different cavity sizes, namely, RCD, âCD, and çCD. In the absence of CD the main reduction product of vinclozoline in the first reduction step is dichloroaniline. An addition of glucose leads to a quantitative change of mechanism with 10 products in
total. Addition of CD, however, leads exclusively to dechlorination of the phenyl ring. The degree of
dechlorination depends strongly on the choice of cyclodextrin molecule. The importance of the complex
formation equilibria in the change of the mechanism is supported by a series of semiempirical AM1 quantum-mechanical calculations. Very good correlation (correlation coefficient 0.995) was obtained between the
complex stabilization energy of the inclusion complex and the degree of pesticide dechlorination. Additionally,
we were able to show that the complexes are stabilized by the formation of intermolecular hydrogen bonds between the host and guest species. CD molecules do not simply act as proton donors in a nonaqueous environment, but also protect parts of the molecule included within the cavity and steer the degradation process toward fewer products
PERFORMANCE OF A GENERAL-PURPOSE ELECTROCHEMICAL INSTRUMENT AIDED BY A STAND-ALONE MICROCOMPUTER SYSTEM IN TRACE ANALYSIS
No full textThe features of a microprocessor-based data acquisition and control unit, dedicated to electrochemical experiments, are described. The menu-selectable software allows smoothing, baseline drawing and subtraction as well as differentiation, even with signal amplitudes of some tenths of nA at signal/noise ratios lower than one, without forcing the data to follow theoretical models. Concentrations of cadmium ion as low as 2 × 10 -7, 5 × 10 -8 and 5 × 10 -9 M can be measured, within 10% accuracy and precision, by using sampled d.c. polarography, staircase voltammetry and fast-sweep differential pulse voltammetry, respectively; this is a consistent improvement on literature data. Depending on the electrochemical technique used, the most significant signal parameters, including derivatives, are measured automatically, listed and used in the decision-making process for chemical characterization
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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