1,720,970 research outputs found
Structural investigation of the c(2x52)R45° surface alloy formed by Ti deposition on Cu(001), Surface Science 601 (2007) 528-535
No full textThe alloying process of Ti deposited on Cu(0 0 1) was studied by means of XPS, LEIS, XPD and LEED intensity analysis. With the sample held at 570 K, a linear decrease of the Cu LEIS signal as a function of the amount of Ti deposited is observed in the early stages of deposition until a constant value is reached. At the onset of the plateau a c(√2 × 5√2)R45° LEED pattern starts to be visible. XPD and LEED intensity measurements were performed for the c(√2 × 5√2)R45° phase prepared depositing ca. 1.5 monolayer of Ti. The angle-scanned XPD curves measured for the phase c(√2 × 5√2)R45° reveal that Ti atoms substitute Cu atoms in the fcc lattice of the substrate. The polar XPD curves show that at least the first four layers of the substrate are involved in the alloying process. We found that the (3 1 0) plane of the Cu4Ti alloy (D1a type-structure) fits, without significant contraction or expansion of the lattice parameters, the c(√2 × 5√2)R45° structure. The intensity versus energy curves of the diffracted beams were calculated on the basis of this structural model using the tensor LEED method. The results of the LEED intensity analysis provide a further evidence of the formation of a slab of Cu4Ti(3 1 0) layers. © 2006 Elsevier B.V. All rights reserved
L'archivio Laterza: lettere di economisti all'editore (1901 - 1959)
No full textIn un recente lavoro sugli Archivi nella Puglia ci si è chiesti se sia vera l’opinione comune secondo cui nel Sud si nasce e poi ci si allontana, portandosi via le proprie carte. Se questa è la regola, la storia che si racconta in questo lavoro è quella di un’eccezione: l’editore Laterza ha infatti richiamato nel Sud, controcorrente, cultura e carte. Questa storia è possibile raccontarla grazie all’Archivio Laterza, un fondo documentario che testimonia gli eventi storici del «secolo breve» e che delinea, sullo sfondo dei grandi avvenimenti, la vita di un gruppo di grandi intellettuali. Questo saggio si occupa degli economisti che hanno avuto contatti più intensi con l’editore, vale a dire Giustino Fortunato, Francesco Saverio Nitti, Maffeo Pantaleoni, Luigi Einaudi e Umberto Ricci
STM study of the nanostructures prepared bydeposition of NiO on Ag(001)
No full textSubmonolayers of nickel oxide were grown on the Ag(001) surface by evaporation of Ni in the presence of O2 at a pressure of 1 × 10−6 mbar. In the early stages of deposition, two-dimensional oxide islands with a (2 × 1) periodicity grow on Ag(001). After annealing at about 500 K, the (2 × 1) single atomic layer transforms into NiO(001) double layer islands. The 1:1 stoichiometry of the film is not influenced by whether the annealing is carried out in vacuum or in the presence of oxygen. However, the oxide islands exhibit different morphologies depending on the O2 pressure during the annealing process
Growth mechanism and structure of nickel deposited on Ag(001)
No full textThe initial growth stages of nickel deposited on Ag(0 0 1) have been investigated by LEIS, XPS, STM and XPD. Embedded atom method (EAM) calculations were performed to obtain information about the dynamics of Ni adatoms on the Ag(0 0 1) surface. Amounts of Ni ranging from submonolayers up to 4 monolayers were deposited on the Ag(0 0 1) surface under UHV conditions at room temperature. The LEIS spectra indicate that the Ni islands are almost completely covered by silver. In agreement with previous studies, STM images show that Ni grows on Ag(0 0 1) forming three dimensional islands. A significant fraction of islands with a thickness of 2-3 atomic layers is present even at coverages as low as 0.1 ML. The observation of islands protruding from the surface with heights below that expected for one atomic layer of Ni covered by one atomic layer of Ag suggests that Ni atoms are incorporated in the outermost layer of the substrate. From the EAM calculations the energy barrier for incorporation of a nickel atom into the outermost layer was found to be 0.19 eV, substantially lower than that for bridge site hopping over the substrate (0.61 eV). On the basis of the EAM calculations, a diffusion mechanism for Ni atoms incorporated within the first layer of the surface is proposed to explain the growth of Ni islands. As far as the geometric structure of the Ni film is concerned, the XPD curves indicate that at a coverage of ≈0.3 ML, the structure of the film is distorted with respect to the fcc lattice. The displacement of the forward scattering peaks towards higher polar angles is consistent with the formation of pseudomorphic Ni islands (i.e. with the same in-plane lattice parameter of the substrate). The XPD results lead to the conclusion that pseudomorphic Ni clusters coexist with undistorted fcc Ni islands. Even at the highest coverage studied here, a fraction of the islands maintains a strained fcc structure. © 2005 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
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
Mechanism of growth and structure of titanium oxide ultrathin films deposited on Cu(001) Surface Science 602 (2008) 1101-1113
No full textThe growth mechanism, composition and structure of ultrathin films of titanium oxide deposited on the Cu(001) surface were investigated by means of XPS, LEIS, LEED and STM. Titanium oxide films were deposited on the Cu(001) surface previously saturated witha (p2 2p2)R45 structure of chemisorbed oxygen. The oxide films were prepared by evaporation of titanium in O2 atmosphere (pO2 in the 106 mbar range) while the substrate temperature was kept at 573 K. The Cu LEIS signal versus the amount of deposited titanium (as determined by means of XPS) indicates the growth of 2D islands in the early stages of deposition. Upon increasing the amount of deposited
titanium multilayer islands begin to grow. The XPS results indicate that the oxide phases formed for Ti coverages above 1ML have a
TiO2 stoichiometry. At very low coverages, a LEED pattern with a centred rectangular unit cell is observed. STM measurements show that at this stage of the growth the oxide islands are incorporated in the outermost layer of the substrate and the removed copper atoms form islands around the oxide regions. The very early stages of titanium oxide growth corresponding to the formation of this rectangular phase were also investigated by Ti deposition on the oxygen chemisorbed phase under UHV conditions at 573 K. In this way it is possible to study the reaction of Ti with chemisorbed oxygen. Upon increasing the Ti coverage above 0.5 ML, an oxide film with a slightly distorted
hexagonal unit cell begins to grow. The quasi-hexagonal phase of titanium oxide can also be formed by annealing at 773 K the
rectangular phase. At higher coverages, when the substrate surface is completely covered by the oxide, the film exhibits a LEED pattern with a regular hexagonal unit cell
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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