1,720,959 research outputs found
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
Precision electrodynamics of unconventional superconductors : microwave spectroscopy and penetration depth
No full textPrecision measurements of the electrodynamics of unconventional superconductors are reported. Measurements of the magnetic penetration depth temperature dependence are made via cavity perturbation and a novel microwave spectrometer gives the surface resistance continuously from 0.05 to 26.5 GHz.
The microwave conductivity of single crystals of YBa₂Cu₃O₆.₅₀ has been measured using the broadband spectrometer. Conductivity spectra were measured after preparing the crystal in the ortho-II phase in which the Cu-O chain oxygens are ordered into alternating full and empty chains. These spectra exhibit features expected for quasiparticle scattering from dilute weak impurities in a d-wave superconductor. The measurements were repeated after reducing the degree of oxygen order in the Cu-O chains. The disordered spectra retain the weak-limit scattering features, however, increased quasiparticle scattering broadens the widths. The conductivity of a new generation of samples, with an order of magnitude lower impurity concentrations, are unchanged from those of the older generation samples. In both generations of crystals the spectral widths are largely determined by residual disorder in the chains.
The electrodynamics of single crystal Ba₀.₇₂K₀.₂₈Fe₂As₂ and Ba(Fe₀.₉₅Co₀.₀₅)₂As₂ have been investigated. Measurements of ∆⋌(T)are used to extract the superfluid density ⋌²(0)/⋌²(T) which is observed to approach Tc linearly indicative of mean-field behaviour. At low-temperatures, the superfluid density obeys the a power law ⋌²(0)/⋌²(T)= 1 - (T/T*)n with n varying from 2.1 to 2.7 for the three crystals studied. At T/Tc ≈ 0.04, all three samples exhibit a step-like feature of order 1 anstrom in the measured penetration depth that is of unknown origin.
The surface resistance of two Ba₀.₇₂K0.₂₈Fe₂As₂ crystals reveal a sample-dependent extrinsic loss. The spectra, however, share a common temperature dependence and follow frequency squared when the extrinsic loss is removed. This frequency dependence translates to a flat quasiparticle conductivity and implies a high scattering rate(～ 200 GHz). The microwave spectroscopy of a Ba(Fe₀.₉₅Co₀.₀₅)₂As₂ sample reveals more anomalous behaviour. Even after subracting of the extrinsic loss, the surface resistance rapidly increases when the frequency scaled by Tc is above 0.04. The resistivity of the Ba(Fe₀.₉₅Co₀.₀₅)₂As₂ sample is an order of magnitude larger than that of the K-doped samples suggesting the anomalous behaviour may be activated by enhanced impurity concentrations.Science, Faculty ofPhysics and Astronomy, Department ofGraduat
Circuits designed to evaluate the cosine and sine functions on the interval −π to π
No full textWe present a pair of simple analog circuits designed to evaluate the cosine and sine of an input voltage that
varies between −π and +π V. The circuit designs are based off of the Taylor series expansions of cos x and
sin x about x = 0 (i.e. Maclaurin series expansions). For cos x and sin x, the series are truncated after the x6
and x5 terms, respectively. The coefficients of the various powers of x in the truncated series are fine tuned
in order to give the best possible approximations to the trigonometric functions. The circuits are implemented
using low-cost analog multiplier and operational amplifier integrated circuits.Science, Irving K. Barber Faculty of (Okanagan)Computer Science, Mathematics, Physics and Statistics, Department of (Okanagan)UnreviewedFacult
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Broadband spectrometer for measuing the low-temperature microwave absorption of unconventional superconductors
No full textA highly sensitive spectrometer has been designed and built to measure the ultralow temperature surface resistance of unconventional superconducting single crystals continuously over a broad range of microwave frequencies. The technique uses bolometric detection to measure the temperature rise of samples that have been exposed to a microwave magnetic field. An in-situ normal metal reference sample is used to calibrate the field strength at the sample site and is vital to the success of the measurement. This broadband technique has already been applied by researches at UBC to make detailed measurements of the conductivity spectrum of YBa₂Cu₃O[sub 6+y] and have revealed, for the first time, the cusp-like line shape expected for a d-wave superconductor. Thus far these measurements have been limited to temperatures above 1 K and there remain several key issues regarding low-energy quasiparticle dynamics in these materials that this new spectrometer will address. A new broadband apparatus has been designed to be used with a ³He/⁴He.dilution refrigerator that can achieve base temperatures less than 50 mK. The main obstacle encountered in adapting this technique for use at lower temperatures is achieving the necessary temperature stability required to reliably perform the measurements. Low-pass thermal filters have been designed and constructed that will substantially suppress any temperature instabilities before they are able to reach the sample thermal stages. An equivalent circuit model was developed and implemented to numerically evaluate the filter performance. This low-temperature microwave spectrometer will be used to uncover new physics regarding low-energy quasiparticle dynamics in YBa₂Cu₃O[sub 6+y] and other materials, such as heavy fermion compounds, that is inaccessible by any other measurement technique.Science, Faculty ofPhysics and Astronomy, Department ofGraduat
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