1,720,965 research outputs found
Diffusive atom transport along step edges on Ag(111) at 295 K
No full textThe entropy-driven relaxation of a unique, non-equilibrium step edge configuration on the Ag(111) surface was observed using time-resolved STM imaging at room temperature. Using the Gibbs-Thomson relation, the relaxation process is quantitatively described as diffusive mass transport in terms of a gradient in the chemical potential along the monoatomic step edge. The STM data directly show that mass transport on Ag(111) is dominated by step edge diffusion at 295 K, and allow an estimate of the corresponding effective energy barrier. We obtain E-eff = 0.49 +/- 0.05 eV and compare this value with recent results on island diffusion studies. (C) 2003 Elsevier B.V. All rights reserved
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 and electronic properties of epitaxial V2O3 thin films
No full textThin films of V2O3 with thickness 4-300 nm were grown on (11 (2) over bar0)-oriented sapphire substrates by reactive dc magnetron sputtering. X-ray diffraction, pole figure measurements and scanning tunnelling microscopy show high crystallinity and epitaxy to the substrate with a faceted surface structure, and the absence of strain. Measurements of the electrical resistivity, scanning tunnelling and x-ray absorption spectroscopy show a metal-insulator transition near 150 K that is connected with the opening Of an energy gap and a characteristic modification of the absorption spectrum at the vanadium-2p and Oxygen-1 s edges. These observations reveal that the V2O3(11 (2) over bar0) films have bulk-like properties
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
Origin of Schottky barriers in gold contacts on GaAs(110)
No full textGold contacts on n-type GaAs(110) have been investigated using scanning tunneling microscopy and spectroscopy in cross-sectional configuration. In spatially resolved current voltage spectroscopy the Schottky barrier potential is visible. We find signatures of delocalized gap states at the interface decaying into the semiconductor and observe a defect density at the interface below 3x10(13) cm(-2). Both findings support that the Fermi level pinning at the Au/GaAs(110) interface is dominated by metal-induced gap states
Kondo resonance of single Co atoms embedded in Cu(111)
No full textThe Kondo resonance of single Co atoms embedded in a Cu matrix has been investigated with tunneling spectroscopy at T=8 K. Dilute magnetic alloys were prepared by homoepitaxial growth of Cu(111) films incorporating approximately 0.1% Co atoms as magnetic scattering centers. The Co impurities in the first layer of the Cu matrix show a characteristic, symmetric dip in the differential conductance around zero bias, indicating the presence of the many-body Abrikosov-Suhl resonance. The corresponding Kondo temperature is found to be T-K=405+/-35 K, which is much higher than previously reported values for Co adsorbate atoms
Thermovoltage mapping of standing electron waves on Au(111) surfaces at low temperatures
No full textStanding-wave patterns of Au(111) surface electrons in the vicinity of monatornic steps were studied by mapping the thermovoltage across the tunneling gap of a low-temperature scanning tunneling microscope (STM). In contrast to other STM spectroscopic methods, the amplitude of the standing-wave oscillations builds up with distance from the step, up to a maximum. When the temperature T is decreased, the position of this maximum shifts outwards proportional to 1/T. This behavior is explained with an analytical expression and also with numerical calculations of the thermovoltage in the framework of the model of Tersoff and Hamann
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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