1,720,955 research outputs found
On the nature of charge-transfer excitations for molecules in aqueous solution: a polarizable QM/MM study
Get PDFWe illustrate the effect of solvation on the nature of electronic excitations of organic molecules which possess excited states of charge-transfer character. The analysis is carried out using both a continuum model and a polarizable QM/MM method that treats the solvent atomistically and embeds each atom in the solvent with a fluctuating charge which responds to the solute quantum-mechanical electrostatic potential in a self-consistent manner. We also show how solvation dynamics can influence the nature of the excited state of molecular systems. The application of the model to aqueous solutions of doxorubicin and a substituted polythiophene derivative shows that the solvent significantly affects the nature the excited states, which results in an enhanced or reduced charge-transfer character as measured using two of the most popular indices for evaluating the distance traveled by the electrons upon excitation
Photochromic fluorescent proteins for high-resolution cellular imaging
No full textThe major goal of this thesis is the investigation of the photophysical and photochemical properties of two new mutant fluorescent proteins from the Aequorea jellyfish family, namely wQL and EYQ1L.
Our target was actually to assess whether the Q69L mutation could positively cooperate with E222Q to improve the photoswitching properties as compared to E222Q alone. In this context, we always compared the mutation effect on each couple, the green one (wQ/wQL) and the yellow one (EYQ1/EYQ1L).
All our experiments highlight the peculiar properties of wQL as RSFP, namely high bright/dark contrast ratio, high off-switching quantum yield and strong resistance to photobleaching.
The high performances of the mutant wQL in terms of photoswitching opens the way to several application in super-resolution fluroescence microscopy with possibly strong implications in terms of biological results
Simulating vertical excitation energies of solvated dyes: From continuum to polarizable discrete modeling
Get PDFWe present a computational study on the spectroscopic properties of UV-Vis absorbing dyes in water solution. We model the solvation environment by using both continuum and discrete models, with and without polarization, to establish how the physical and chemical properties of the solute–solvent interaction may affect the spectroscopic response of aqueous systems. Seven different compounds were chosen, representing different classes of organic molecules. The classical atomistic description of the solvent molecules was enriched with polarization effects treated by means of the fluctuating charges (FQ) model, propagated to the first-order response function of the quantum-mechanical (QM) solute to include its effects withing the modeling of the electronic excitations of the systems. Results obtained with the QM/FQ model were compared with those from continuum solvation models as well as nonpolarizable atomistic models, and then confronted with the experimental values to determine the accuracy that can be expected with each level of theory. Moreover, a thorough structural analysis using molecular dynamics simulations is provided for each system
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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