1,721,133 research outputs found
Bouncing and cyclic universes from brane models
No full textWe consider a D3-brane as boundary of a five-dimensional charged anti-de Sitter black hole. We show that the charge of the black hole induces a regular cosmological evolution for the scale factor of the brane, with a smooth transition between a contracting and an eventual expanding phase. Simple analytical solutions can be obtained in the case of a vanishing effective cosmological constant on the brane. A nonvanishing cosmological constant, or the inclusion of radiation on the brane, does not spoil the regularity of these solutions at small radii, and observational constraints such as the ones from primordial nucleosynthesis can be easily met. Fluctuations of brane fields remain in the linear regime provided the minimal size of the scale factor is sufficiently large. We conclude with an analysis of the Cardy–Verlinde formula in this set up
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
Two tryptophans at the active site of UDP-glucose 4-epimerase from Kluyveromyces fragilis
No full textEfficient fluorescence energy transfer from aromatic residues to the pyridine moiety of the bound coenzyme (NAD) of UDP-glucose 4-epimerase from Kluyveromyces fragilis had been reported earlier (Mukherji, S., and Bhaduri, A. (1992) J. Biol. Chem. 267, 11709-11713). We have employed N-bromosuccinimide (NBS) to identify tryptophan as the exclusive aromatic donor in the energy transfer. The characteristic UV absorption spectrum associated with Trp oxidation is observed during NBS modification of two of the four Trp residues of native epimerase along with concomitant inactivation of the enzyme. Excellent correlation between the observed inactivation and abolition of fluorescence energy transfer to coenzyme from Trp in epimerase upon treatment with NBS implicates the involvement of the same two tryptophans in both catalytic activity and fluorescence energy transfer. SDS-polyacrylamide gel electrophoresis and fluorescence data preclude gross structural/conformational changes in epimerase due to NBS oxidation. The susceptible tryptophans do not reside at the substrate binding site as substrates and UMP fail to protect against NBS modification. However, failure of sodium borohydride to reduce the bound NAD in the NBS-inactivated epimerase suggests that the reactive tryptophans are close to the coenzyme. Tryptophan fluorescence lifetime values of 1.9 and 3.9 ns for the native and 3.5 ns for the NBS-modified epimerase, complemented by a linear Stern-Volmer plot (effective Stern- Volmer constant = 2.85 M-1) of acrylamide quenching, suggest that the two key tryptophans are buried close to an intrinsic quencher, presumably NAD
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
