1,721,041 research outputs found
Photon Antibunching in Complex Intermolecular Fluorescence Quenching Kinetics
No full textWe present a novel fluorescence spectroscopic method, which combines fluorescence antibunching, time-correlated single-photon counting (TCSPC), and steady-state emission spectroscopy, to study chemical reactions at the single molecule level. We exemplify our method on investigating intermolecular fluorescence quenching of Rhodamine110 by aniline. We demonstrate that the combination of measurements of fluorescence antibunching, fluorescence lifetime, and fluorescence steady state intensity, captures the full picture of the complex quenching kinetics, which involves static and dynamics quenching, and which cannot be seen by steady-state or lifetime measurements alone
Photon Antibunching Reveals Static and Dynamic Quenching Interaction of Tryptophan with Atto-655
No full textFluorescence correlation spectroscopy (FCS) of photoinduced electron transfer (PET) between the dye Atto-655 and the amino acid tryptophan has been extensively used for studying fast conformational dynamics of small disordered peptides and proteins. However, a precise understanding of the quenching mechanism and its exact rates that would explain ensemble as well as single-molecule spectroscopy results is still lacking. In this contribution, a general unified model for intermolecular PET between Atto-655 and tryptophan is developed, which involves ground-state complex formation, quenching sphere of action, and dynamic quenching at the single-molecule level. We present measurements of fluorescence antibunching, fluorescence lifetime, and steady-state fluorescence intensity and absorbance and demonstrate that our model is capable to describe all results in a global and coherent manner
Binding Constant Determined from the Angstrom-Scale Change in Hydrodynamic Radius of Transferrin upon Binding with Europium Using Dual-Focus Fluorescence Correlation Spectroscopy
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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
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
Determining Metal Ion Complexation Kinetics with Fluorescent Ligands by Using Fluorescence Correlation Spectroscopy
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