1,721,005 research outputs found
The Gecko® Approach to Friction: A Novel Teaching Learning Sequence
No full textWe here propose a novel teaching–learning sequence on tribology, based on the experimental investigation of Gecko® Nanoplast®, a bio-inspired micro-structured synthetic material with peculiar tribological properties. Measurements of static and dynamic friction show that Gecko® does not obey to Leonardo-Amontons’ law, thus providing a way to introduce the key concept of real—as opposed to nominal—contact area. As in ‘real’ material-science research, investigation of the Gecko® macroscopic behavior is combined with its structural determination, based on both optical microscopy observations and on diffraction measurements. The sequence has been tested on a group of honors high-school students with encouraging results
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
Quantum-size-effects and temperature-dependence of low-energy electron excitations in thin Bi crystals
No full textAppropriate 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
Structural study of CH3S self assembled monolayers on Au(111)
No full textWe present preliminary results of an experimental investigation of ordered phases of CH3S chemisorbed
on Au(111). The self-assembled monolayer has been grown by dosing dimethyl disulfide in ultrahigh
vacuum at different substrate temperatures between 200 K and 320 K and following different protocols.
The monolayers have been characterized by means of low-energy He atom scattering with time-of-flight
detection in a temperature range between 150 K and 300 K. The observed diffraction patterns show that
the main periodicity is well-described by the (3 x 4) overlayer of the Au(111) lattice, coexisting with the
(√3 x √3) periodicity, in agreement with previous results obtained by means of low-energy electron
diffraction
Disclosing the Microscopic Picture: An Interdisciplinary Investigation of Friction and Wetting Using a Gecko-Inspired Tape
Full text linkWe propose an innovative approach to teaching friction. Our approach aims to educate students on its microscopic nature by highlighting its origin in intermolecular interactions. We have designed a teaching sequence (TS) based on a set of experimental investigations of the properties of a gecko-inspired tape at different length scales. The TS has been conceived to unravel the peculiar behavior of this man-made, commercially available biomimetic material and to train students to identify the connection between the micrometer-scale patterning and the peculiar tribological properties. Specifically, our approach compares friction (and adhesion) to wetting, occurring at solid/solid and solid/liquid interfaces, respectively. The aim is to scaffold a correct mental model of real interfaces and disclose the common origin of both phenomena in intermolecular interactions. The TS has been devised according to the design-based research scheme and it was inspired by the Investigative Science Learning Environment (ISLE) and the 5E paradigms. It has been tested and tuned with students at level 3 in the International Standard Classification of Education (ISCED), during several on-campus stages. We report here the details and results of pre- and post-tests, which demonstrate the effectiveness of our method. Specifically, we measure success in terms of the students' comprehension of the link between contact area and friction and of the role of intermolecular forces. We are confident that the learning experience with our TS will lead students to recognize the enormous potential impact of surface patterning in technological applications, in a curiosity-driven manner that will likely result in students' interest in quantitative studies of science and technology
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