1,721,037 research outputs found
Human Immunodeficiency Virus (HIV-1) Auxiliary Protein Vif and Cellular APOBEC Deaminases: Their Roles Unveiled?
No full textThe major DNA polymerase in cultured plant cells: partial purification and correlation with cell multiplication.
No full texta dna polymerase activity was isolated from cells of Oryza sativa L. grown in suspension culture. Molecular mass (ca. 180,000), optimal requirement for pH (neutral), Mg2+ ((5- 10 mM), Mn2+ (1 mM), template preference (activated DNA), lack of activity to N-ethylmaleimide and ionic strength are similar to those of the vertebrate alpha-plymerase. Like DNA polymerase alpha, the DNA polymerase described in this work is the most abundant in proliferating cells of Oryza sativaL., Parthenoscissus tricuspidata (Siebold et Zucc.) Planchon, Acer pseudoplatanus L. and Medicago sativa L. and responds to changes in the rate of cell multiplication. We therefore postulate that this alpha-like DNA polymerase is the replicating enzyme of plant cells
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
The stereoselective targeting of a specific enzyme-substrate complex is the molecular mechanism for the synergic inhibition of HIV-1 reverse transcriptase by (R)-(-)-PPO464. A novel generation of nonnucleoside inhibitors.
No full textThe human immunodeficiency virus type 1 (HIV-1) nonnucleoside reverse transcriptase (RT) inhibitor pyrrolopyridooxazepinone (PPO) derivative, (+/-)-PPO294, was shown to be active toward wild type and mutated HIV-1 RT and to act synergistically in combination with 3'-azido-3'-deoxythymidine (Campiani, G., Morelli, E., Fabbrini, M., Nacci, V., Greco, G., Novellino, E., Ramunno, A., Maga, G., Spadari, S., Caliendo, G., Bergamini, A., Faggioli, E., Uccella, I., Bolacchi, F., Marini, S., (1999) J. Med. Chant. 42, 4462-4470). The (+/-)-PPO294 racemate was resolved into its pure enantiomers, and the absolute configuration was determined by x-ray analysis. Only one enantiomer, (R)-(-)-PPO464, displayed antiviral activity against both the wild type and the K103N mutant HIV-1 RT and was found to interact exclusively with the reaction intermediate formed by RT complexed with both the DNA and the nucleotide substrates. Being the first compound of its class to display this behavior, (R)-(-)-PPO464 is the representative of a novel generation of nonnucleoside inhibitors. (R)(-)-PPO464 showed significant synergism when tested in combination with other RT inhibitors and efficiently inhibited viral replication when tested against the laboratory strain HIV-1 IIIB or against either wild type or multidrug-resistant clinical isolates. Pharmacokinetic studies in mice and rats showed a more favorable profile for (R)-(-)-PPO464 than for the corresponding racemate. (R)-(-)-PPO464 was also found to easily cross the blood-brain barrier. The coadministration of the HIV-1 protease inhibitor ritonavir increased the bioavailability of (R)-(-)-PPO464, having little effect on its plasma and brain elimination rates
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
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