1,721,106 research outputs found
Persistent organic pollutants in food: public health implications
Full text linkPersistent organic pollutants are a heterogeneous group of chemicals sharing a number a common properties, including long term persistence and diffusion in the environment, and bioaccumulation through the food chain. Animal experiments and epidemiological studies suggest that the most sensitive adverse effects, such as disturbances on metabolism, development, and reproductive system, may occur in the range of current human exposure. Although the potential cancer risk of persistent organic pollutants remains undefined, the implementation of actions to reduce the exposure to these substances, which mainly occurs through the diet, is important
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
Studies on the sex pheromone of Dacus oleae. Analysis of the substances contained in the rectal gland
No full text17 substances contained in the rectal glands of Dacus oleae have been, identified by GC-MS techniques. The synthesis of 3 isomeric spiroketals allows us definitively to assign the structure of 1,7-dioxaspiro-[5,5]-undecane to the most volatile compound
DESIGN AND SYNTHESIS OF NEW PEPTIDOMIMETICS AS POTENTIAL INHIBITORS OF HIV-1 PROTEASE
No full textBeing HIV-1 protease responsible for the post-translational processing of the viral polyproteins and the subsequent generation of the structural and functional proteins, it is an important target for the treatment of AIDS. HIV-1 protease is an aspartyl protease active as an homodimer. Every single chain is built of 99 amino acids and the active site is at the interface between the two monomeric units. The commercially available protease inhibitors target the active site but several mutations within or outside the active site led to the emergence of resistance to these compounds.
This thesis deals with the design and synthesis of peptides and peptidomimetics as potential inhibitors of HIV-1 protease that can circumvent drug resistance and that can be alternatives to active site PR inhibitors.
Two different approaches were applied to reach our target.
The first one, described in chapter 2, deals with the folding of the protease monomer that proceeds following a hierarchical succession of events starting from the formation of local elementary structures (LES), which contain highly conserved amino acids. The interaction between two complementary LES represents the first step of the folding process. Since these LES are so important for the protein, the virus can not afford their mutation. We describe here the synthesis of small peptides with the same sequence as one of these critical regions (p-LES) and of peptidomimetics analogues to the p-LES that could bind to the complementary region preventing the correct folding. CD studies of interaction between synthesized peptides and native sequence of the protease are presented.
The second approach, described in chapter 3, consists in the design and synthesis of compounds mimetics of the terminal -sheet of the HIV-1 protease. The dimeric form of HIV-1 protease is stabilized by the antiparallel -sheet formed between the C- and N-terminal regions of the protein.
Constrained molecular tongs based on a naphtalene scaffold in which peptidomimetic strands are attached through a carboxylpropyl link disrupt the dimeric enzyme with loss of activity. We are now concerned in decreasing the peptidic character and increasing the hydrosolubility of the molecular tongs. For that purpose, we have conceived two different strategies: 1) the synthesis of new peptidomimetic strands with increased hydrophilicity and 2) the introduction of hydrophilic groups on the scaffold mainly via metal-catalyzed cross coupling reactions. We describe here the synthesis and the biological activity against wild-type and mutated HIV-1 protease of these new molecular tongs
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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