1,720,965 research outputs found
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
Tissue microarrays : a cross-over validation tool for research
No full textBackground: Genomic, transcriptomic, proteomic have increased the importance of tissues in the discovery and validation of prognostic, diagnostic and therapeutic biomarkers. Human tissue has become a strategic and unavoidable tool for all –omics technologies including high-throughput in situ proteomics to study signal transduction and protein-protein interactions. Tissue microarray (TMA) systems allow the study of hundreds of samples (paraffin embedded tissues or cells) on a single slide for hystochemical analysis. The “Galileo CK4500” (www.isenet.it) is a high-throughput semiautomatic and computer-assisted TMA platform with the unique feature of picking cores of interest in a tissue or cell block and extract nucleic acids for subsequent molecular biology analysis.
Methods: Harvested and agarose re-suspended Neural Stem Cells (NSCs) were fixed in PFA (4%) and treated like the human glioblastoma xenografts tissue donor block selected for the specific study. Cores of cells or tissues (previously selected) from the donor blocks were placed by the arrayer either in a second paraffin block or in appropriate vessels to be processed for nucleic acid extraction.
Results: TMA and CLMA (Cell Line Microarray) technology were used to analyse glioblastoma xenografts and NSCs, to verify stemness and tripotency. From the cores DNA, RNA and microRNAs were successfully extracted.
Conclusions: The Galileo CK4500 platform is a powerful pathology tool to simultaneously screen a huge number of tissues or cell lines treated in different conditions or with different phenotypes. This technique will be particularly useful to obtain immunophenotypical information and to perform epigenetic studies in specific selected areas of a biological sample
Genetic stability and cryopreservation of banked neural stem cells
No full textThe use of stem cells in medical research is increasing steadily since they, likely, will constitute a renewable source of cells for the treatment and study of human diseases.
For this purpose the application of standard quality controls, testing basic behaviour and general sterility of the cell cultures, are not enough to guarantee their safety in clinical settings.
Sophisticated testing, as the detection of contaminating pathogens and assessment of genetic stability, represent a fundamental tool to contain the risks and preserve original features of stem cells. For these reasons, we routinely perform on human stem cells (i) viral screening (HSV1-2, EBV, CMV, HBV, HCV, HIV, HPV), (ii) high resolution genetic analysis such as comparative genomic hybridization array (aCGH) and (iii) telomere analysis.
Telomere maintenance appears to be essential for the chromosomal integrity and the prolonged persistence of stem cell function. We analyzed hTERT mRNA expression, relative telomerase activity and average telomere length in human Neural Stem (NS) cell lines of different origin: CB660 and CB660SP derived from foetal cortex and foetal spinal cord; Hes4-hNCPC (Neural Crest Progenitor Cells) derived from human embryonic stem cell (hES) and AF22 derived from induced Pluripotent Stem (iPS) cells. Although human NS cells CB660, CB660SP and Hes4-hNCPC preserved a normal karyotype, their telomeric length shortened during expansion due to the absence of telomerase. This implies that human NS cells may undergo replicative ageing. Instead, the AF22 cell line showed a high telomerase activity and a high hTERT expression when compared to hES-derived NS cells. This confirms their great proliferation and differentiation potential even if maintaining high telomerase activity, characteristic of pluripotent cells.
Furthermore, if these cells will ever be used in clinical applications, safer cryoprotectants need to be adopted to assure genomic stability after long term storage.
We have developed and applied a cryopreservation reagent (trehalose-based) that successfully cryopreserved human fetal- and iPS-derived NS cells. Cell’s viability, stability and differentiation capacity were tested in relation to the standard reagents and method (Cryostor10®)
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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