1,720,983 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
Beyond the Lorenz-Mie theory: Simulating light-scattering by arbitrary particles with the discrete dipole approximation
No full textInternational audienceInteraction of light with particles is a central concept in applications ranging from remote sensing of aerosols or interstellar dust to advanced imaging techniques and various molecular sensing involving nanoparticles. Corresponding simulations are not trivial for particles of complex shape and internal structure, while the discrete dipole approximation (DDA) is one of the versatile methods to handle such problems. The DDA has a simple underlying physical picture and, at the same time, is a numerically exact method – a special case of volume-discretization method of moments. Notably, the DDA is applicable to almost any electromagnetic problem involving non-magnetic particles. It can handle arbitrary shaped beams, particles in complex environments (e.g., on a multi-layered substrate), and simulate a broad range of quasi-classical electromagnetic phenomena (such as emission enhancement, near-field radiative heat transfer, and electron energy-loss spectroscopy). I will also discuss computational aspects and modern DDA formulations. The latter are implemented in open-source DDA codes, such as ADDA, which largely explains the method’s popularity. Finally, I will highlight current capabilities and limitations (open questions) of the DDA
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
The discrete dipole approximation for scattering simulations of subwavelength particles
No full textInternational audienceElectromagnetic scattering is widely used in remote sensing of various objects ranging from metal nanoparticles and macromolecules to atmospheric aerosols and interstellar dust. All these applications require accurate simulations, which are not trivial for particles of arbitrary shape and internal structure. The discrete dipole approximation (DDA) is one of the versatile methods to handle such problems.This talk will begin with an introduction to the DDA, covering both the basic underlying physical picture and a rigorous derivation starting from the integral form of Maxwell’s equation for the electric field. This derivation emphasizes that the DDA is a numerically exact method and a special case of volume-discretization method of moments. Notably, the DDA is applicable to almost any electromagnetic problem involving non-magnetic particles. It can handle arbitrary shaped beams, particles in complex environments (e.g., on a multi-layered substrate), and simulate a broad range of quasi-classical electromagnetic phenomena (such as emission enhancement, near-field radiative heat transfer, and electron energy-loss spectroscopy).Although the DDA applies to a wide range of particle sizes, the talk will focus specifically on subwavelength ones, discussing the corresponding computational aspects and modern DDA formulations. The latter are implemented in open-source DDA codes, such as ADDA, which largely explains the method’s popularity. Finally, I will highlight current capabilities and limitations (open questions) of the DDA in application to subwavelength systems
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
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
Microwave scattering by rough polyhedral particles on a surface
No full textInternational audienceThe electromagnetic (EM) scattering by non-symmetric wavelength-scale particles on a planar surface has numerous applications in the remote sensing of planetary bodies, both in planetary and geo-sciences. We conduct numerical simulations of EM scattering by rough polyhedral particles (with 12 or 20 faces) using the discrete-dipole approximation and contrast the results to that of spheres. The particles have permittivities corresponding to common minerals in the microwave regime (ϵr=4.7+0.016i and 7.8+0.09i), and a size-frequency distribution (SFD) consistent with the observed scattering properties (power-law distribution of size parameters between 0.5 and 8 with an index from −2.5 to −3.5). The assumed substrate permittivity 2.4+0.012i corresponds to a powdered regolith. We present what roles the particle roundness, permittivity, and SFD for a realistic range of parameters play in the EM scattering properties as a function of incidence angle with a focus on backscattering in microwave-remote-sensing applications. The particle roundness and SFD have a clearly observable effect on the polarimetric properties, while the role of permittivity is relatively minor (in the studied range). Among various backscattering observables, the circular polarization ratio is the least sensitive to the decrease of the upper boundary (down to a size parameter of 3) and the index of the SFD
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