1,720,966 research outputs found
Combined contribution of TbAT1 and TbMRPA to drug resistance in Trypanosoma brucei (Short communication)
No full text
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
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
Isolation, propagation and characterization of "Trypanosoma brucei gambiense" from human African trypanosomosis patients in south Sudan
Full text linkSleeping sickness or Human African trypanosomosis (HAT) is a protozoal disease that is
transmitted by tsetse fly vectors in Africa. Sleeping sickness due to T. b. gambiense is a major
public health problem in countries in central and western Africa including Angola, Uganda,
Democratic Republic of Congo (DRC) and Sudan. High rates of relapses (>20%) following
melarsoprol treatment have been reported in many treatment centres including the MSF-F
treatment centre at Ibba in south Sudan. The treatment failures could be due to individual
(patients) variation in the drug pharmacokinetics, the patient’s immune responses, or drug
resistant parasites.
There is a growing interest in the elucidation of the reason(s) for relapses after melarsoprol
treatment. Since the drug levels in blood or CSF do not differ between relapse and
successfully treated patients, drug resistance has been suggested as a likely cause for
melarsoprol treatment failures. There are no recently isolated parasites from high-relapse
areas and hence detailed studies have been hindered. The objective of this PhD study was to
isolate and characterize (phenotypically and genotypically) T. b. gambiense from HAT
patients in the MSF-F treatment centre at Ibba.
In a first step, the protocols for the isolation of bloodstream forms of the parasite needed to be
improved. As such, the suitability of the commercial cryomedium TriladylÒ developed for
bull semen was evaluated. We found that, the cryopreservation of T. b. gambiense in this
medium led to a better survival of the trypanosomes than in the standard 10% glycerol. The
samples (blood (50) and CSF (2)) from HAT patients were therefore cryopreserved using
Triladyl® and stored at -150oC in nitrogen vapour in a dry shipper. In the laboratory, attempts
to propagate the isolated parasites in rodents were carried out. Of the 42 parasite positive
isolates, 18 (43%) could be propagated in laboratory rodents (immunosuppressed Mastomys
natalensis and SCID mice). Stabilates of these T. b. gambiense isolates are stored in two
cryobanks at the Trypanosomiasis Research Centre (TRC) of the Kenya Agricultural Research
Institute (KARI), Nairobi and the Swiss Tropical Institute (STI), Basel.
After the initial isolation of these T. b. gambiense isolates in immunosuppressed M. natalensis
or SCID mice, further in vivo propagation could be done in various immunosuppressed rodent
species (Swiss White mice, M. natalensis, C57/bl, C3H, and BALB/C). The highest
parasitaemia were achieved in C57/bl and BALB/C mice. The rodents however had to be
immunosuppressed with cyclophosphamide at 300mg/kg prior to infection and repeated once
a week at 200mg/kg. This scheme (cryopreservation and subsequent propagation) allows the
isolation of T. b. gambiense from various endemic areas and therefore enhances monitoring of
drug resistant trypanosomes.
The eighteen T. b. gambiense isolates were found to be sensitive to melarsoprol, melarsen
oxide, and diminazene. The gene that codes for the P2 transporter, TbATI, was amplified by
PCR and sequenced. The sequences were almost identical to the TbAT1sensitive reference,
except for one point mutation, C1384T resulting in the amino acid change proline-462 to
serine. None of the described TbAT1resistant-type mutations were detected. In summary we
found, in a sleeping sickness focus where melarsoprol had to be abandoned due to the high
incidence of treatment failures, no evidence for drug resistant trypanosomes or for
TbAT1resistant-type alleles of the P2 transporter.
In conclusion, our findings cast doubts on the current suggestion that melarsoprol resistant
parasites are the cause of the high rate of treatment failures reported. However, it is important
to note that the number of isolates tested was still small and it is vital that more isolates,
especially from relapse patients be teste
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