1,721,000 research outputs found
The effects of enzyme inactivation and incubation buffer on digestion in situ with restriction endonucleases
No full textDNA alteration induced by ultraviolet light in human metaphase chromosomes substituted with 5′-bromodeoxy uridine: monitoring by monoclonal antibodies to double-stranded and single stranded DNA
No full textFixed human metaphase chromosomes, whose DNA had been substituted with 5'-bromodeoxyuridine (BrdUrd) for two rounds of replication (TB/BB) or for one round in BrdUrd followed by another round in thymidine (TT/BT), were treated with ultraviolet light (UV), in the presence or in the absence of 33258 Hoechst, to produce sister chromatid differentiation (SCD). Giemsa staining was compared with staining with monoclonal antibodies to double-stranded or single-stranded DNA. We confirmed that UV acts by debrominating BrdUrd-stubstituted DNA but showed that debromination alone cannot explain all our findings. We postulated that UV-induced protein-protein cross-linking, occurring to a different extent in differently BrdUrd-substituted chromatids, may also be invoked in explaining our data. Lastly, the different behaviour of unifilarly substituted TB as opposed to BT chromatids in UV-treated chromosomes, allowed us to hypothesize that such chromatids may differ depending on whether or not newly synthesized DNA is formed on a BrdUrd-containing stran
Dry biobanking as a conservation tool in the Anthropocene
Full text linkSpecies are going extinct at an alarming rate, termed by some as the sixth mass extinction event in the history of Earth. Many are the causes for this but in the end, all converge to one entity – humans. Since we are the cause, we also hold the key to making the change. Any change, however, will take time, and for some species this could be too long. While working on possible solutions, we also have the responsibility to buy time for those species on the verge of extinction. Genome resource banks, in the form of cryobanks, where samples are maintained under liquid nitrogen, are already in existence but they come with a host of drawbacks. Biomimicry – innovation inspired by Nature, has been a huge source for ideas. Searching methods that Nature utilizes to preserve biological systems for extended periods of time, we realize that drying rather than freezing is the method of choice. We thus argue here in favor of preserving at least part of the samples from critically endangered species in dry biobanks, a much safer, cost-effective, biobanking approach
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
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