1,720,969 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
P-type Ca channel activation by membrane depolarisation induces maturation in pig oocytes
No full textThe presence on pig oolemma of voltage gated Ca channels (VGCC), whose activity can be influenced by depolarisation, has been investigated exposing the oocytes to a chemical depolarisation reproducing the physiological one. To this aim and to characterise the type of VGCC present, we analysed intracellular Ca variations during perfusion of oocytes with physiological or depolarising solutions containing different selective inhibitors of VGCC. We also evaluated the effect of their activation or inhibition on oocyte maturation and the pathway involved in transduction of the depolarising stimulus to the oocyte. The results demonstrate that P type VGCC are present on pig oolemma and that their activation by depolarisation produces a prompt a sustained Ca raise able to induce the resumption of oocyte meiotic maturation through the transduction pathway involving the Ca-calmodulin dependent kinase (CaMKII).[...
An ovine preimmune foetal model to study the effect of cellular therapies for myocardic diseases
No full textThe ovine foetus is an ideal model for preclinical medical studies of cell therapies. It allows us to follow the behaviour of repairing cells inserted into a favourable physiological microenvironment in an animal species more closely related to humans than the rat or rabbit. In addition, the preimmune foetus is able to support cell engraftment by eliminating the problems of tissue rejection. Labelled fibroblasts were transplanted into the myocardium of preimmune foetuses, injecting through a disposable bowed mouth pipette into the left ventricular apex. Two weeks later, foetuses were isolated by laparotomy and each heart was collected and morphologically analyzed. No cases of abortion or postoperative complications in mothers or foetuses occurred. Macroscopically, the isolated hearts did not display any abnormality apart from a small petechia at the injection site. Tissue sections did not show any sign of acute tissue inflammation and viable labelled cells were easily identified among myocardiocytes. This model system guarantees a reduced damage in the engrafted tissue, a high survival and easy retrieval of the injected cells. The direct injection of cells into the preimmune ovine foetus myocardium can be satisfactorily performed to control tissue delivery and to reduce the risk of cell loss and dispersion
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
Complessi cumulo-oocita isolati da follicoli antrali migliorano la competenza meiotica di oociti in accrescimento
No full textOsteogenic potential of sheep amniotic epithelial stem cells
No full textAmniotic membranes and amniotic fluid have attracted increased attention as possible sources of stem cells to be used for clinical application in regenerative medicine. However, the biology of these cells and the signals required to effectively direct their differentiation are still largely unknown. This work was designed to define stemness properties in sheep amniotic epithelial cells (AECs) and evaluate their osteogenic potential in vitro. Sheep AECs express cell adhesion markers CD29 and CD49 and the pluripotent stem cell markers Oct4, SOX2, Nanog, and TERT that are typical of mesenchymal stem cells. Under specific inductive culture conditions, AECs undergo prompt osteogenic differentiation with extensive extracellular matrix mineralization, and the remarkable plasticity of these cells is progressively reduced after six expansion passages.[...
Production of meiotically competent oocytes using an in vitro folliculogenesis culture system
No full textDispelling 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
- …
