1,721,036 research outputs found
Projection-operator route to the generalized darken equation
No full textThe generalized Darken equation (GDE) for collective diffusion in lattice gases is derived in the framework of the Mori projection-operator technique. It is shown that the GDE is obtained if the dynamical correlations between successive transitions in the lattice gas are not taken into account
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
Collective and tracer diffusion in low-coverage adsorbates
No full textIn the present paper both the self (or tracer) diffusion coefficient Ds and the chemical (or collective) diffusion coefficient Dc are computed for the Ising-Peierls lattice gas with nearest-neighbour interactions as functions of coverage ?. The two quantities are calculated in the framework of the Mori projection-operator formalism. Here Ds and Dc are studied for coverages up to and memory effects are neglected. It turns out that at low lateral coupling Ds depends on coverage more strongly than Dc. The collective diffusion coefficient is more sensitive to the increase oflateral interactions than the self diffusion coefficient. In the range of coverages under investigation, Dc is an increasing function of ? in the repulsive case, whereas, if attractive interactions are present, it decreases as ? increases. The theoretical results given by different choices of the jump dynamics are shown and briefly 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
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