1,721,735 research outputs found
Photodarkening, Photobrightening, and the Role of Color Centers in Emerging Applications of Lanthanide-Based Upconverting Nanomaterials
No full textUpconverting nanoparticles (UCNPs) compose a class of luminescent materials that utilize the unique wavelength-converting properties of lanthanide (Ln) ions for light-harvesting applications, photonics technologies, and biological imaging and sensing experiments. Recent advances in UCNP design have shed light on the properties of local color centers, both intrinsic and controllably induced, within these materials and their potential influence on UCNP photophysics. In this review, we describe fundamental studies of color centers in Ln-based materials, including research into their origins and their roles in observed photodarkening and photobrightening mechanisms. We place particular focus on the new functionalities that are enabled by harnessing the properties of color centers within Ln-doped nanocrystals, illustrated through applications in afterglow-based bioimaging, X-ray detection, all-inorganic nanocrystal photoswitching, and fully rewritable optical patterning and memory.
DISSECTING TITIN INTO ITS STRUCTURAL MOTIFS - IDENTIFICATION OF AN ALPHA-HELIX MOTIF NEAR THE TITIN N-TERMINUS
No full textTitin, also known as connectin, is a giant modular protein specifically found in vertebrate striated muscle. Since the huge size of titin does not allow a direct structure determination, we have started a long-term project to characterize the protein by cutting it into smaller domains or structural units. The major part of the titin sequence is assembled by modules approximately 100 amino acids long that belong to two major protein superfamilies. Most of these modules are linked together by stretches of variable length with unique sequence. No direct structural characterization has been achieved so far for any of these linkers. We present here a study of a stretch located in the titin N-terminus and part of a linker between two modules. Our attention was drawn toward this region because it shows 100% probability to form a coiled coil when analyzed by a prediction program. A synthetic 38 amino acid peptide spanning such a sequence was studied in aqueous solution by circular dichroism, nuclear magnetic resonance, and analytical ultracentrifugation at various pH, salt, and peptide concentrations. Under all conditions, it shows a strong tendency to form alpha-helical structures. In the presence of salt, this conformation is associated with the formation of helical bundles below pH 5. Above pH 5, any aggregate breaks, and the titin peptide is a monomeric helix in equilibrium with its random coil conformation. We discuss the factors which stabilize the helical conformation and the possible role of this stretch in vivo
Pairing correlations in nuclear matter with realistic interactions
No full textSome aspects of the superfluidity in nuclear matter and neutron matter are numerically investigated by using realistic interactions. It is shown that the gap equation with bare pairing interaction contains the particle-particle correlations corresponding to the ladder diagrams. The effects of the short range part of the interaction on the gap function are discussed in momentum space in connection with the weak coupling approximation. Extending the BCS theory to coupled channels, it is found that the pairing between neutron and proton in the S-3(1)-3D1 channel is surprisingly large, of the order of about 10 MeV
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
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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