1,720,998 research outputs found
Cosmic Ray elemental composition study by using the lateral particle density distribution in showers induced by primaries in the 1 − 104 TeV energy range
No full textAbstract. Important information on the origin
of high-energy Cosmic Rays can be obtained by
studying their composition. In this paper a study
on the elemental Cosmic Ray composition by using
the lateral particle density distributions in Extensive
Air Showers (EAS) is presented. EASs induced by
protons, He nuclei, CNO group, NeMgSi group and
Fe nuclei were simulated in the energy range 1-10000
TeV. The lateral particle density distribution was
estimated, an unfolding procedure to separate the
different mass groups is discussed
Structure and phase transitions of the Sn/Ge(111) surface
No full textThe low-temperature phase of Sn/Ge(1 1 1) 3 × 3 is studied by means of first-principle calculations at the DFT level and in the GW approximation. Experimental STM images taken at 80 K are presented and compared with theoretical predictions. This analysis allows to give support to a geometry in which one Sn adatom is higher than the other two in the surface unit cell and excludes the complementary geometry in which two Sn adatoms are higher than the third. Concerning the very low temperature phase (T < 30 K), we show that from a purely energetic point of view a sqrt(3) × sqrt(3) geometry cannot be excluded, being almost degenerate with the 3 × 3 phase
alfa-Sn/Ge(lll) and alfa-Sn/Si(lll) surfaces studied by stm measurements and ab-initio calculations
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Two-dimensional antiferromagnetic ordering of the Mn/GaAs(001) interface
No full textIn this paper we report on an x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) investigation of the Mn/GaAs(001) interface. The deposition of Mn in the submonolayer regime on the GaAs(001) surface at 390 degrees C induces a (2 x 1) reconstruction which evolves to a (2 x 2) by increasing the Mn amount. The combined information from XAS and XMCD indicates that the Mn atoms are located on surface sites possessing an almost square symmetry with a limited hybridization of the Mn electronic levels with the GaAs ones. The Mn atoms present a magnetic moment ranging between 4.9 and 4.2 mu(B) depending on the surface reconstruction. The Mn/GaAs(001) interface shows a paramagnetic behavior with an average magnetic moment which decreases by increasing the Mn amount. This variation of the surface magnetization is interpreted as an antiferromagnetic coupling of the Mn magnetic moments as the surface density of Mn atoms is increased. A further increase of the Mn amount after the (2 x 2) transition leads to the formation of Mn aggregates on the sample surface
The role of kinetics on the Mn-induced reconstructions of the GaAs(001) surface
No full textA combined scanning tunneling microscopy and low-energy electron diffraction investigation of
the Mn/GaAs(001) interface formation is reported. The interface, grown on a (2 4) reconstructed
substrate produced by molecular beam epitaxy, was studied as a function of Mn evaporation with
thickness ranging from 1/8 ML to 1 ML. The interaction of Mn atoms with the semiconductor
surface is strong and leads to surface reconstructions involving a rearrangement of the two outmost
atomic layers of the substrate. For Mn thickness lower than 1/2 ML, the surface is characterized by
a (2 1) periodicity. Conversely, when the Mn deposition is increased to 1/2 ML the surface
reconstruction is strongly dependent on the preparation procedure. If Mn deposition is performed
on the substrate at 390 C, a fully ordered surface characterized by a clear (2 2) reconstruction is
obtained, whereas, annealing the sample after Mn deposition, gives a disordered surface with a
(2 1) symmetry. An intermediate phase between (2 1) and (2 2) is found for Mn depositions
in between 1/4 and 1/2 ML. No further structural evolution was observed for both preparation
methods above 1/2 ML coverage
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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