1,721,002 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
The polymorphism of enzyme MTHFR in children suffering from migraine ad epilepsy
No full textThe C677T variant in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with increased levels of circulating homocysteine and is a mild risk factor for vascular disease. Mild Hcy elevation (>15 mmol L−1) in the adult population is associated with increased risk of myocardial infarction, stroke, peripheral arterial disease and venous thrombosis.[1,2,3] The MTHFR 677CT mutation is frequent in Caucasians; MTHFR mutant allele occurs commonly in 5% to 15% of the population, and the heterozygosis is over 40%. The C677T polymorphism of the MTHFR gene has been associated with different diseases such as stroke, coronary artery disease, bipolar disorder, schizophrenia and depression. Homozygosis for MTHFR 677 CT mutations is more frequent in epileptic patients compared with healthy controls (23% vs. 12%) and heterozygosis is about 52%. Lipton[1] showed that Hcy may have excitotoxicity to neurons as an agonist of the glutamate binding site of the N-methyl-Daspartate (NMDA) receptors. Migraine, with and without aura (MA and MO), is a prevalent and complex neurovascular disorder that may also be affected by genetically influenced hyperhomocysteinaemia
Aim of this study is the evaluation of incidence of mutation of enzyme MTHFR in the children suffering from two disease, epilepsy and migraine as in comorbility, as without comorbility.
MATERIALS AND METHODS
32 patients suffering from headache observed during 3 months and 34 children affected by epilepsy observed during the same time represent the sample of this study. At the first observation in day hospital are determined the homocisteinaemia levels and mutation C677 of enzyme MTHFR. In the sample is studied MR brain and EEG. In the familial history is considered the headache, the epilepsy, the stroke and cardiovascular disease. The homocisteinaemia is evaluated by immunological fluorescent method (FPIA) The mutation of enzyme C677 is studied by technique of qualititative Real-Time PCR.
RESULTS
27 patients suffering from generalized epilepsy, 7 from partial epilepsy. In the 18%of these patients there is C677 enzyme mutation and 7% show homozygous condition. Among 32 children suffering from headache, 17 have TTH, 9 MO, and 6 MA. 50% show MTHFR mutation. The allele is present in the 83% of MO and in 87% of MA and homozygosis condition is present in 22% of children. The values of homocisteinaemia are higher in the homozygous than heterozygous patients (9.48 μmol/L vs. 8.3 μmol/L) and this condition is more evident in the migraines than epileptic patients. In the 50% of the sample with C677 mutation there are MR lesions as cerebrovascular disease. 1 child shows the results of ischemic event in the foetal life. We underline the history of 2 patient’s hemiplegic suffering, one from migraine, one from epilepsy.
DISCUSSION
Kowa et al. [1] originally reported a positive association between the MTHFR C677T variant and migraine in a Japanese case control cohort. These researchers indicated an increased risk of migraine in Japanese individuals possessing the homozygous T/T genotype. Stratified analyses specifically showed that the T/T genotype was significantly over-represented in these Japanese patients with MA compared to non-migraine controls (40% vs. 9.6%), producing an OR of ~6. These positive findings were reinforced by another recent migraine case-control study conducted in a Turkish population. These researchers reported that the MTHFR C677T is associated with migraine and also indicated that the T/T genotype specifically increased risk of MA (OR ~10). It is important to note that the frequency of the MTHFR 677T allele, and indeed migraine prevalence, is known to vary substantially among different ethnic populations. Thus, this study supports the findings of other authors and shows the hypothetical role of this genetically aspects in the comorbility migraine - epilepsy.
1. BMC Medicine 2 (2004):3
2. Cephalalgia 28 (2008): 376-382
3 Eur J Radiol 2009 feb 1
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