1,721,505 research outputs found
W. J. Crozier and S. Hecht
No full textW. J. Crozier and S. Hecht sitting down examining a book together.Inscriptions on image and/or album page: #1586Digitized by: MBLWHOI Libraryimage/jpg black and white image reformatted digitalPhotograph
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
NANOSCALE MONITORING OF RESPONSIVE SUPRAMOLECULAR NANOSTRUCTURES AT THE SOLID-LIQUID INTERFACE
No full textThe self-assembly of small molecular modules into non-covalently linked polymeric nanostructures is a subject of continuous interest [1]. In particular, supramolecular structures with a high degree of order can be obtained through the self-association of organic molecules on flat solid surfaces. Such structures can be used as scaffolds to position electrically/optically active groups in pre-determined locations in 2D [2] thereby paving the way towards a wide range of applications, e.g. in electronic and optical devices. Among weak interactions, H-bonding offers high control over the process of molecular self-assembly because it combines reversibility, directionality, specificity and cooperativity. Such a unique character is the basis of sophisticated programs for self-assembly such as those based on the Watson–Crick base pairing which directs the formation of the helical structure of DNA.
While the self-assembly of guanines into G-quartet based architectures on solid surfaces has been studied by Scanning Tunneling Microscopy (STM) under ultrahigh vacuum (UHV) [3], STM explorations at the solid-liquid interface have been primarily carried out on guanosine derivatives [4]. In this lecture we will present a sub-molecularly resolved STM study at the solid-liquid interface of the metal templated reversible assembly/reassembly process of a N9-alkylguanine into highly ordered quartets and ribbons on highly oriented pyrolitic graphite (HOPG) surfaces. The self-assembly of guanine derivatives on HOPG has been studied as neat component[5] and upon sub-sequent addition of cryptand [2.2.2] molecules, potassium picrate and triflic acid to trigger the reversible interconversion between two different highly ordered supramolecular motifs, i.e. H-bonded ribbon and G-quartet based architectures. In-situ STM imaging provided the first direct evidence on the sub-nm scale of a dynamer operating at surfaces. [6]
Finally we will also provide the first example of sub-molecularly resolved vertically oriented switchable chromophores in physisorbed monolayers by monitoring the cis-trans isomerization of a physisorbed azobenzene at surfaces. [7]
The nanoscale visualization of such supramolecular interconversion at the solid-liquid interface opens new avenues towards understanding the mechanism of formation and functioning of complex architectures. Furthermore, the in-situ reversible assembly and re-assembly between two highly ordered supramolecular structures at a given surface represents the first step towards the generation of nanopatterned responsive architectures.
[1] J. M. Lehn, Science, 295, 2002, 2400.
[2] G. P. Spada, S. Lena, S. Masiero, S. Pieraccini, M. Surin, P. Samorì, Adv. Mater., 2008, 20, 2433; A. Ciesielski, L. Piot, P. Samorì, A. Jouaiti, M. W. Hosseini, Adv. Mater., 2009, 21, 1131.
[3] R. Otero, M. Schock, L. M. Molina, E. Laegsgaard, I. Stensgaard, B. Hammer, F. Besenbacher, Angew. Chem. Int. Ed., 2005, 44, 2270.
[4] G. Gottarelli, S. Masiero, E. Mezzina, S. Pieraccini, J. P. Rabe, P. Samorì, G. P. Spada, Chem. Eur. J., 2000, 6, 3242; T. Giorgi, S. Lena, P. Mariani, M. A. Cremonini, S. Masiero, S. Pieraccini, J. P. Rabe, P. Samorì, G. P. Spada, G. Gottarelli, J. Am. Chem. Soc., 2003, 125, 14741; S. Lena, G. Brancolini, G. Gottarelli, P. Mariani, S. Masiero, A. Venturini, V. Palermo, O. Pandoli, S. Pieraccini, P. Samorì, G. P. Spada, Chem. Eur. J., 2007, 13, 3757.
[5] A. Ciesielski, R. Perone, S. Pieraccini, G.P. Spada, P. Samorì, Chem. Commun 2010, 46, 4493.
[6] A. Ciesielski, S. Lena, S. Masiero, G. P. Spada, P. Samorì, Angew. Chem. Int. Ed. 2010, 49, 1963.
[7] D. Bléger, A. Ciesielski, P. Samorì, S. Hecht, 2010 submitted
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
Tuning the interaction between carbon nanotubes and dipole switches: the influence of the change of the nanotube-spiropyran distance
No full textThe non-covalent functionalization of carbon nanotubes with spiropyran molecules, serving as optically addressable dipole switches, is reported. Two kinds of pyrene–spiropyran-based dyads with spacers of different lengths resulting in different switch–tube distances were investigated. While both surfactants were able to form stable carbon nanotube suspensions, the different distances between the switch and the tube affected both of the components' optical properties. In the case of the shorter spacer, the nanotubes' luminescence as well as the merocyanine absorption band were red-shifted and furthermore, the rate of the merocyanine → spiropyran thermal back isomerization was decreased
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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