1,721,064 research outputs found
Concurrence of Plasmodium falciparum dhfr and crt mutations in northern Ghana.
Full text linkBACKGROUND: Both chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) are failing drugs in much of sub-Saharan Africa. Previous findings suggest an association between resistance to CQ and to SP in vivo, in vitro, and on the molecular level. METHODS: In 126 Ghanaian children with uncomplicated malaria, associations between mutations conferring resistance in the Plasmodium falciparum dihydrofolate reductase (dhfr; SP) and chloroquine resistance transporter (crt; CQ) genes, concentrations of residual antimalarial drugs, and gametocyte carriage were examined. RESULTS: Mutant dhfr alleles and the CQ-resistance allele crt T76 were strongly associated with each other. Isolates exhibiting the dhfr triple mutation seven times more likely also contained crt T76 parasites as compared to isolates without the dhfr triple variant (P = 0.0001). Moreover, both, isolates with the dhfr triple mutation (adjusted OR, 3.2 (95%CI, 1.0-10.4)) and with crt T76 (adjusted OR, 14.5 (1.4-150.8)) were associated with an increased likelihood of pre-treatment gametocytaemia. However, crt T76 did not correlate with gametocytaemia following SP treatment and no selection of crt T76 in SP treatment failure isolates was observed. CONCLUSION: These results confirm an association between CQ and SP resistance markers in isolates from northern Ghana. This could indicate accelerated development of resistance to SP if CQ resistance is already present, or vice versa. Considering the enhanced transmission potential as reflected by the increased proportion of isolates containing gametocytes when resistant parasites are present, co-resistance can be expected to spread in this area. However, the underlying mechanism leading to this constellation remains obscure
Genetic variants of human erythrocyte glucose 6-phosphate dehydrogenase: new variants in West Africa characterized by column chromatography.
No full textNeurological research on clinically normal HIV-1-positive patients (WRC 1A-3B) - A prospective study
No full textRolfs A, Curio G, Hampl H, et al. Neurological research on clinically normal HIV-1-positive patients (WRC 1A-3B) - A prospective study. In: Kubicki S, Henkes H, Bienzle U, Pohle HD, eds. HIV and the nervous system : proceedings of the Symposium on Neurological Aspects in AIDS. Stuttgart u.a.: G. Fischer; 1988: 71-80
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
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