1,720,973 research outputs found
CSF levels of cyclic nucleotides in primary intracranial neoplasms: a preliminary report
No full textRecent evidence indicates that cyclic nucleotides are of importance for general and neurosurgical oncology, especially with respect to the contact-inhibition mechanisms and tumour cell growth. This preliminary report deals with the CSF levels of c-AMP and c-GMP in primary neoplasms in children and to problems related to the blood-brain barrier. Some cases of medulloblastoma were studied as well as a few cases of brain stem glioma and cystic astrocytoma. The importance of some rather unusual findings seems undebatable, i.e., the marked increase in c-GMP values usually observed in medulloblastoma and the decrease of c-AMP, that is fairly common in all malignant neoplasms. The main changes in the c-AMP/c-GMP ratio are also discussed
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
Functional characterisation of the antioxidant system in Drosophila melanogaster, after metals exposure.
No full textReactive oxygen species (ROS) are a normal byproduct of aerobic metabolism playing an important role in cell signaling and immunity when their production is regulated or controlled by antioxidant enzymes. Reduced expression and/or activity of these proteins lead to an excess of ROS production and oxidative stress, accelerating aging and neurodegeneration. For example, amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by motoneuron loss and some familial cases (fALS) are linked to mutations of superoxide dismutase type-1 (SOD1). Many animal models, such as Drosophila melanogaster, are used as useful tool to study this disease, focusing the attention on the different mutant SOD1s but not considering the complex relationships of functional complementarity between SOD1 and the other components of the enzymatic antioxidant system. In the present work we study, for the first time, the gene expression, by qRT-PCR, of SOD1 together with that of superoxide dismutase type-2, catalase, glutathione peroxidases and peroxiredoxins in wild type D. melanogaster, exposed to various concentration of copper or cadmium, used as pro-oxidants. The aim was to determine the adequate experimental condition to employ with D. melanogaster SOD1 mutants. On the basis of our results, copper is the major inducer of all considered enzymes, and the dose of 1.0 mM seems to be the more suitable. Catalase is temporally co-expressed with SOD1, at least in males and the gene expression of other enzymes seems to be temporally uncorrelated to SOD1. Other important indication will be obtained by biochemical quantification of activity for all considered enzymes and the evaluation of ROS production, that are now in progress
Peripheral trigeminal nerve field stimulation: report of 6 cases
No full textObject. Peripheral nerve field stimulation has been successfully used for many neuropathic syndromes. However, it has been reported as a treatment for trigeminal neuropathic pain or persistent idiopathic facial pain only in the recent years. Methods. The authors present a review of the literature and their own series of 6 patients who were treated with peripheral nerve stimulation for facial neuropathic pain, reporting excellent pain relief and subsequent better social relations and quality of life. Results. On average, pain scores in these patients decreased from 10 to 2.7 on the visual analog scale during a 17-month follow-up (range 0-32 months). The authors also observed the ability to decrease trigeminal pain with occipital nerve stimulation, clinically confirming the previously reported existence of a close anatomical connection between the trigeminal and occipital nerves (trigeminocervical nucleus). Conclusions. Peripheral nerve field stimulation of the trigeminal and occipital nerves is a safe and effective treatment for trigeminal neuropathic pain and persistent idiopathic facial pain, when patients are strictly selected and electrodes are correctly placed under the hyperalgesia strip at the periphery of the allodynia region
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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