1,720,957 research outputs found
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
Water exchange across the erythrocyte plasma membrane studied by HR-MAS NMR spectroscopy
No full textWater exchange across the plasma membrane of erythrocytes (red blood cells (RBCs)) was studied by means of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Under HR-MAS conditions, the centrifugal force causes the splitting of RBC suspensions into a two-phase system composed of a central core of cell free water and an outer layer of tightly packed cells. Water belonging to each of these phases gives rise to two separated resonances. Chemical exchange between them is not detectable on the chemical shift or saturation transfer (ST) NMR time scale because of the physical separation between the phases. When the RBCs are dispersed and immobilized within a matrix made of cross-linked albumin, the splitting into a two-phase system is prevented and a single exchange-averaged peak for water is detected in H-1 HR-MAS NMR spectra. The lineshape of this peak is dependent on transmembrane exchange kinetics, since MAS averages out all the anisotropic magnetic interactions that are responsible for additional line-broadening under conventional liquid conditions. Line-shape analysis according to a two-site exchange model yielded a residence lifetime on the order of about 10 ms (at 37 degrees C) for a water molecule within the intracellular compartment, which is not too far from the generally accepted value of 9.6-14.8 ms
Modulation of the antioxidant activity of HO scavengers by albumin binding: a 19F-NMR study
No full textThe interaction between different HOradical dot radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF3PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF3PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF3PAF from HOradical dot radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF3PAF and trolox were found to bind to BSA with association constants in the order of 5 × 103 M−1 and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF3PAF.The interaction between different HO. radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF3PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF3PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF3PAF from HO. radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF3PAF and trolox were found to bind to BSA with association constants in the order of 5×103M-1 and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF3PAF. © 2003 Elsevier Inc. All rights reserved
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
HR-MAS of Cells: A “Cellular Water Shift” due to Water-Protein Interactions?
No full textUnder HR-MAS conditions, cells are subjected to high centrifugal forces that may cause irreversible cell damage. First, conditions have been defined to monitor and keep to a minimum unwanted effects in HR-MAS spectra arising from the loss of cell integrity. Then, the HR-MAS spectra of reasonably intact cells have been analyzed. Cell suspensions subjected to MAS rates as low as 1 kHz split into a two-compartment system that is composed of a cell-rich phase (H2Oi) and a cell-free phase (H2Oo). Each of these phases is characterized by its own water 1H-NMR signal. Transport of water molecules between the cell-rich and cell-free compartments is limited by the very low contact area between the two compartments, and water exchange dynamics consequently fall into the slow exchange limit on the NMR timescale. Since the exchange between the two water populations is "frozen," the separation between the H 2Oo and H2Oi water signals (Δνwater) detected in an HR-MAS experiment is not affected by chemical exchange but reflects only chemical differences in the two environments. Different cell lines show a different Δνwater, leading to the concept of "cellular water shift." This shift roughly correlates with the cellular protein content, supporting the view that the most important determinant of the cellular water shift is the interaction between water and proteins in the intracellular compartment
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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