1,722,194 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
Thyrotropinomas
No full textThyrotropinomas are easily recognized, owing to the availability of ultrasensitive thyropin immunometric assays. These methods allow a clear distinction between patients who have suppressed and those who have nonsuppressed circulating thyrotropin concentrations. In the latter, it is mandatory to perform a differential diagnosis, as the management of the two disorders is completely different, and failure to recognize the presence of a thyrotropinoma may result in dramatic consequences. Adenomectomy is the firstline treatment of thyrotropinomas, followed by irradiation in the case of surgical failure. Medical treatment with somatostatin analogs is effective in reducing thyrotropin secretion in more than 90% of cases
Pituitary incidentalomas
No full textThe widespread use of sensitive neuroradiological imaging studies (i.e. computed tomography scan and magnetic resonance imaging) over the last years lead to the diagnosis of an increased number of asymptomatic pituitary lesions. The management of these so-called "pituitary incidentalomas" is still controversial, due to the limited data so far available on both the clinical relevance and the natural history of such incidentally discovered pituitary masses. Most pituitary incidentalomas are less than 1 cm in diameter (microincidentalomas) and are pituitary adenomas. Although these tumours are in general hormonally inactive, all the patients with incidentalomas should be screened for pituitary hypo- or hyper-function. Macroincidentalomas have greater growth potential and, when associated with hypopituitarism and/or visual disturbances, should be surgically removed. Conversely, incidentalomas not associated with hormonal alterations and dimensionally stable could be managed conservatively. This review will focus on the last data on the natural history and clinical management of pituitary incidentalomas
Medical management of thyrotropin-secreting pituitary adenomas
No full textThyrotropin-secreting pituitary tumors (TSH-omas) are a rare cause of hyperthyroidism and account for less than 1% of all pituitary adenomas. It is however noteworthy that the number of reported cases tripled in the last years as a consequence of the routine use of ultrasensitive immunometric assays for measuring TSH levels. Contrary to previous RIAs, ultrasensitive TSH assays allow a clear distinction between patients with suppressed and those with non-suppressed circulating TSH concentrations, i.e. between patients with primary hyperthyroidism (Graves' disease or toxic nodular goiter) and those with central hyperthyroidism (TSH-oma or pituitary resistance to thyroid hormone action). Failure to recognize the presence of a TSH-oma may result in dramatic consequences, such as improper thyroid ablation that may cause the pituitary tumor volume to further expand. The medical treatment of TSH-omas mainly rests on the administration of somatostatin analogs, such as octreotide and lanreotide. In fact, administration of dopamine agonists failed to persistently block TSH secretion in almost all patients and caused tumor shrinkage only in those with combined hypersecretion of TSH and PRL. On the contrary, somatostatin analogs were effective in reducing TSH and α-subunit secretion in more than 90% of cases with consequent normalization, of FT4 and FT3 levels and restoration of the euthyroid state in the majority of them. In about one third of patients, a clear shrinkage of tumor mass and vision improvement could be demonstrated. Tachyphylaxis, cholelithiasis and carbohydrate intolerance occurred in a minority of treated patients. Whether somatostatin analog treatment may be an alternative to surgery and/or irradiation in patients with TSH-oma remains to be established. Nonetheless, the long-acting somatostatin preparations represent a useful tool for long-term treatment of such a rare pituitary tumors
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
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