1,721,110 research outputs found
Charlotte Warakaulle and Hans Peter Beck signing the IPPOG MoU Collaboration agreement
No full textCharlotte Warakaulle (DG-DI-IR) and Hans Peter Beck (Uni. Bern and IPPOG Chairperson) signing the IPPOG MoU Collaboration agreemen
"Plasmodium falciparum" transfection technology for the analysis of "var" gene regulation and knockout investigation
Full text linkMalaria is an infectious disease caused by protozoans of the genus
Plasmodium, which are injected by the bite of an infected female Anopheles
mosquito during a blood meal. Out of the four species that infect humans, P.
falciparum is the most important. About 40% of the world’s population is at
risk and 500 million cases of malaria occur every year, mainly in sub-
Saharan Africa. Due arising resistance of mosquitoes against insecticides,
the lack of a malaria vaccine, and emerging resistance of parasites against
established drugs, research into new drugs and vaccine targets is most
important.
Morbidity is associated with adherence of infected red blood cells (iRBC) to
endothelial tissue thereby obstructing the blood flow. The major protein
conferring this cytoadherence is the P. falciparum erythrocyte membrane
protein 1 (PfEMP1) anchored in the erythrocyte membrane of infected red
blood cells (iRBCs). PfEMP1 is encoded by the var gene family that consists
of approximately 60 members in the haploid genome of the 3D7 strain. var
genes are expressed mutually exclusive, i.e. only one var gene is expressed
in a parasite at a time and the rest is silenced. In this thesis we were
interested in the regulation of expression and silencing of var genes. For this
purpose we generated transgenic parasite lines that harbored plasmids
expressing luciferase under the control of various fragments of the var gene
upstream region. By comparing luciferase activities in the different lines we
identified the core promoter, two activator-binding sites and a repressorbinding
site. Additionally, we identified a regulatory sequence on the var
upstream region that interacts with the var intron during silencing. Using
quantitative RT-PCR with specific primers for every var gene we were unable
to confirm that the var upstream regions on the transfected plasmids were
recognized by the machinery that ensures mutually exclusive transcription.
In the second part of this thesis, we evaluated phosphodiesterase 1 (PDE1)
as a possible drug target in P. falciparum by creating a knockout parasite
line. PDEs are known drug targets in humans where selective PDE inhibitors
are being used to treat a wide range of diseases. In trypanosomiasis
research PDE inhibitors are promising drug candidates against sleeping
sickness, Nagana or Chagas’ disease. Out of the four PDEs described for P.
falciparum we focused on PfPDE1, which is expressed in blood stage
parasites and in gametocytes and sporozoites. We observed a slightly faster
growth of the knockout parasite line compared to the wildtype indicating that
the knockout parasite had a shorter erythrocytic lifecycle. We found that
PfPDE1 is responsible for 20% of the total cGMP activity observed in late
blood stage parasites and that there is no rescue mechanism of the
remaining PDEs to compensate for the loss of activity. We were not able to
localize PfPDE1 in the parasite. The fact that we could delete PfPDE1 clearly
shows that it is not an essential gene in blood stage forms of P. falciparum
and hence not a good drug target. Nevertheless we created a useful tool to
investigate the role of PfPDE1 in the development of sexual parasite forms
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
Erstens kommt es anders, als man zweitens denkt : mit an Sicherheit grenzender Wahrscheinlichkeit – logisches Denken und Zufall
No full textRezension zu: Hans-Hermann Dubben und Hans-Peter Beck-Bornholdt : Mit an Wahrscheinlichkeit grenzender Sicherheit : logisches Denken und Zufall. rororo science. Rowohlt Taschenbuch Verlag, Reinbek 2005, 2. Auflage Januar 2006, ISBN 3-499-61902-4, 219 Seiten, 8,90 Euro
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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