1,720,963 research outputs found
Metallurgical characterisation of a historical metal tie-rod from Milan Cathedral
No full textOne tie-rod from Milan Cathedral (15th century) recently broke in a defective cross-section. In order to infer the causes of failure, a metallurgical characterisation was performed, the results of which are discussed here. First, a visual inspection of the specimen was performed. Next, the fracture surface was analysed using a Scanning Electron Microscope (SEM) combined with Energy Dispersive X-Ray Spectrometry (EDXS) to detect the failure modes involved. A cross-section close to the failure surface was investigated by means of Stereoscopy, Light Optical Microscopy (LOM), SEM and EDXS in order to identify the microstructural compounds and characterise the slag inclusions. Vickers and Rockwell hardness tests were also carried out to correlate microstructural observations with mechanical properties. A strong relationship between failure and defects due to forging was observed, which is a particularly noteworthy result with regard to the representativeness of laboratory tests and the viability of in-situ inspection
Atomistic Simulation of Phase Transitions and Charge Mobility for the Organic Semiconductor Ph-BTBT-C10
Full text linkWe present a computational study of the molecular organization and charge mobility of Ph-BTBT-C10, a high performance organic semiconductor of considerable current interest. We have observed for the first time by atomistic molecular dynamics the formation of an ordered smectic phase on cooling down from the isotropic melt and upon heating the crystal, for this system, in good agreement with experiment. Although we could observe only a smectic A and not a smectic E phase, the temperature variation of the hole mobility estimated from hopping model calculations reproduces the main features of experiments. The crystal phase is characterized by high mobility bilayers defined by the aromatic π-conjugated cores, but it is effectively insulating in the orthogonal direction. The smectic phase is characterized by more disordered monolayers, which have a good in-plane mobility and a lower, but still appreciable, degree of charge transport across the layers. This feature may be advantageous for applications requiring materials with evenly balanced, three-dimensional conduction paths
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
On the radical behavior of large polycyclic aromatic hydrocarbons in soot formation and oxidation
Full text linkThe mechanism of evolution of polycyclic aromatic hydrocarbons (PAHs) into carbonaceous particles in combustion, atmosphere, and interstellar space has been the subject of intense debate. Recently, there has been emerging evidence supporting resonantly-stabilized radicals as key players in PAH growth. In this work, we build on this hypothesis and propose that, beyond a critical size, PAH reactivity can be assimilated to that of radicals. We found that odd-C-numbered PAHs embedding 5-membered rings rapidly lose a hydrogen atom to form resonantly-stabilized radicals in combustion conditions, while even-C-numbered PAHs react as open-shell rather than closed-shell molecules independently of temperature, as usually assumed. Acenes were used as molecular models of large even-C-numbered PAHs. The construction of a kinetic model including these findings allows to interpret experimental soot oxidation data otherwise irreconcilable with existing chemical kinetic mechanisms
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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