1,721,113 research outputs found
Exploring dry storage as an alternative biobanking strategy inspired by Nature
No full textBiobanking is a rapidly growing industry, covering diverse fields such as human medicine, farm animal production, laboratory animals record keeping, and wildlife conservation. Presently, biobanking is done almost exclusively by cryopreservation, followed by maintenance of the samples under liquid nitrogen. Cryopreservation has satisfactory efficiency but it comes with a host of problems, and the process is highly species-specific. Like in many other walks of life, we turn to Nature in search for better alternatives. Nature opted for controlled drying rather than water preservation via freezing when long-term preservation is desired, a strategy known as ‘anhydrobiosis’. To achieve reversible drying, anhydrobiotic organisms utilise an assortment of protective materials, including disaccharides, late embryogenesis abundant proteins, anhydrin, heat shock protein, and more. Once dry, desiccation-tolerant organisms can survive extended periods of time and be resistant to extreme environmental stressors. Over the past 70 years researchers attempted applying this idea to preserve desiccation-sensitive mammalian cells in the dry form. At present dried cells mostly do not resume biological activity upon rehydration. The DNA, however, is often well preserved to allow utilisation in advanced reproductive techniques. Spermatozoa are by far the most commonly dried cell type, primarily from mice and bulls. A number of drying approaches have been applied, with freeze-drying taking the lead. To date offspring have been produced from dried spermatozoa in mouse, rat, hamster, rabbit, and horse. No offspring were produced from dried somatic cells. Desiccation experiences a sharp increase in interest and research output in recent years. Presented here is an overview of dry preservation, its possible applications, the open questions the field is still facing, and some suggested directions for the future
Nuclear dynamics and developmental potential of sheep nuclear transfer embryos treated with protein kinase inhibitor 6-dimethylaminopurine
No full textPhonological priming and tip-of-the-tongue state: evidence from young and older italian adults
No full textAbstract: The tip-of-the-tongue phenomenon (TOT) is a lexical retrieval failure coupled with a strong feeling of being on the verge of recall. An occasional TOT state is normal for people of all ages, but it becomes more frequent with aging. TOTs occur when semantic and lexical representations corresponding to a word are activated but activation of phonological information about the word is incomplete. One of the most influential explanations of the TOT phenomenon is the transmission
-deficit model developed by Burke and colleagues (Burke et al. 1991; Burke, & Shafto 2004) who proposed that activation of phonology fails because connections to phonological representations become weak due to three causes: aging of the speaker, infrequent activation and lack of recent activation of representations. In this study we tested some of the predictions of the transmission deficit model
with Italian speakers, inducing TOT states in 15 young and 15 older adults. Participants were asked questions that are correctly answered by single words. Half of the target to-be-answered words were nouns and half were proper names. Half of the trials were preceded by a phonological prime and
half were not. The results showed that older adults experienced more TOT states than young adults
in all the conditions. Phonological priming facilitated words retrieval only for older participants and differences between proper and common nouns did not emerge
Cloning of endangered mammalian species: any progress?
No full textAttempts through somatic cell nuclear transfer to expand wild populations that have shrunk to critical numbers is a logical extension of the successful cloning of mammals. However, although the first mammal was cloned 10 years ago, nuclear reprogramming remains phenomenological, with abnormal gene expression and epigenetic deregulation being associated with the cloning process. In addition, although cloning of wild animals using host oocytes from different species has been successful, little is known about the implication of partial or total mitochondrial DNA heteroplasmy in cloned embryos, fetuses and offspring. Finally, there is a need for suitable foster mothers for inter-intra specific cloned embryos. Considering these issues, the limited success achieved in cloning endangered animals is not surprising. However, optimism comes from the rapid gain in the understanding of the molecular clues underlying nuclear reprogramming. If it is possible to achieve a controlled reversal of the differentiated state of a cell then it is probable that other issues that impair the cloning of endangered animals, such as the inter-intra species oocyte or womb donor, will be overcome in the medium term
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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