1,720,958 research outputs found
EELS CROSS-SECTION CALCULATIONS ON SI(111)2X1
No full textA quantitative calculation of the EEL spectra of Si(111)2 x 1 has been performed. We reproduced the aximuthal dependence, the characteristic behaviour at low primary energies and the effect of the analyzer angular acceptance observed in existing experimental results
1ST-PRINCIPLES CALCULATION OF ANISOTROPIC REFLECTANCE AT THE GAAS(110) SURFACE
No full textThe optical properties of the GaAs(110) surface are studied by means of self-consistent local-density slab calculations. It is found that a large contribution to the calculated anisotropy of the clean surface reflectance is related to transitions which do not involve surface states. Comparison is made with differential reflectivity and reflectance anisotropy experiments
it Ab initio calculations of the quasiparticle and absorption spectra of clusters: the sodium tetrameter
No full textWe report the first ab initio quasiparticle calculation in a real cluster Na4 within Hedin's GW approximation for the valence electron self-energy. Our approach avoids the summations over empty states, and also eliminates the problem of residual interactions between the periodic images. Self-energy corrections open the local density approximation gap by more than 2 eV; finite-size effects on screening are shown to play an important role. The absorption spectrum calculated by including excitonic effects using our ab initio screened interaction gives a good account of the experimental photodepletion data
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
STRUCTURAL MODELS OF RECONSTRUCTED Si(110) SURFACE PHASES
No full textStructural models are proposed for the wide class of experimentally observed superstructures on the Si(110) surface: both for the case of Si(110) "16 X 2" reconstruction and for the superstructures stabilized by Ni or Cu contamination, like (4 X 5), (2 X 1) and (5 X 1). These models are based on semi-empirical tight-binding total energy calculations for model subunits, on surface lattice dynamics experiments and also on scanning tunnelling microscope measurements. These models consist of a variety of building blocks, namely: new type of pi-bonded dimers, adatoms, atoms with unsaturated dangling bonds, regular sequences of surface steps and missing rows. Surface stresses due to the pi-dimer or adatom formation and Ni contamination are considered to be the driving force of the Si(110) reconstructions
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
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