1,721,167 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
Torque and energy transfer in periodic systems
No full textInternational audienceIn the first part we will show a study of the Casimir torque between two metallic one-dimensional gratings rotated by an angle θ with respect to each other. We find that, for infinitely extended gratings, the Casimir energy is anomalouslydiscontinuous at θ = 0, due to a critical zero-order geometric transition between a 2D- and a 1D-periodicsystem. We will comment on the relevant implication of this finding.In the second part I will discuss the Radiative heat transfer (RHT) and radiative thermal energy (RTE) for two-dimensional (2D) nanoparticle ensembles in the framework of many-body radiative heat transfer theory. We consider nanoparticles made of different materials: metals (Ag), polar dielectrics (SiC), or insulator-metallic phase-change materials(VO2). We start by investigating the RHT between two parallel 2D finite-size square-lattice nanoparticleensembles, with particular attention to many-body interactions (MBI) effects. We fix the particle radius (a)as the smallest length scale, and we describe the electromagnetic scattering from particles within the dipoleapproximation. Depending on the minimal distance between the in-plane particles (the lattice spacing p forperiodic systems), on the separation d between the two lattice and on the thermal wavelength,we systematically analyze the different physical regimes characterizing the RHT. Four regimes are identified,rarefied regime, dense regime, non-MBI regime, and MBI regime, respectively
Torque and energy transfer in periodicsystems
No full textInternational audienceIn the first part we will show a study of the Casimir torque between two metallic one-dimensional gratings rotated by an angle θ with respect to each other. We find that, for infinitely extended gratings, the Casimir energy is anomalouslydiscontinuous at θ = 0, due to a critical zero-order geometric transition between a 2D- and a 1D-periodicsystem. We will comment on the relevant implication of this finding.In the second part I will discuss the Radiative heat transfer (RHT) and radiative thermal energy (RTE) for two-dimensional (2D) nanoparticle ensembles in the framework of many-body radiative heat transfer theory. We consider nanoparticles made of different materials: metals (Ag), polar dielectrics (SiC), or insulator-metallic phase-change materials(VO2). We start by investigating the RHT between two parallel 2D finite-size square-lattice nanoparticleensembles, with particular attention to many-body interactions (MBI) effects. We fix the particle radius (a)as the smallest length scale, and we describe the electromagnetic scattering from particles within the dipoleapproximation. Depending on the minimal distance between the in-plane particles (the lattice spacing p forperiodic systems), on the separation d between the two lattice and on the thermal wavelength,we systematically analyze the different physical regimes characterizing the RHT. Four regimes are identified,rarefied regime, dense regime, non-MBI regime, and MBI regime, respectively
Spontaneous breaking of time-reversal symmetry and time-crystal states in chiral atomic systems
No full textInternational audiencee present a theoretical study of the interaction between an atom characterized by a degenerate ground state and a reciprocal environment, such as a semiconductor nanoparticle, without the presence of external bias [1]. Our analysis reveals that the combined influence of the electron's intrinsic spin magnetic moment on the environment and the chiral atomic dipolar transitions may lead to either the spontaneous breaking of time-reversal symmetry or the emergence of time-crystal-like states with remarkably long relaxation times. Our findings introduce a mechanism for the spontaneous breaking of time-reversal symmetry in atomic systems, and unveil an exciting opportunity to engineer a nonreciprocal response at the nanoscale, exclusively driven by the quantum vacuum fluctuations.[1] Mario G. Silveirinha, Hugo Terças, and Mauro Antezza, Phys. Rev. B 108, 235154 (2023
Non-Equilibrium Quantum Manipulation: Entanglement, Quantum Thermal Machines, Energy Transport
No full textSéminaires du 18-07-2018 à Kavli Institute of Theoretical Physics (KITP), Santa Barbarra (USA)
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