1,720,959 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
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
99mTc-Sesta-MIBI thyroid scan in the differential diagnosis of amiodarone-induced thyrotoxicosis.
No full textBackground: Amiodarone-induced thyrotoxicosis (AIT) may be caused by excessive thyroid hormone synthesis and release (AIT I) or by a destructive process (AIT II). This differentiation is considered essential for the selective therapeutic choice.
Purpose: To evaluate the usefulness of 99mTc-sestaMIBI (MIBI) thyroid scintigraphy in addition to other diagnostic tools in the differential diagnosis of AIT.
Subjects and methods: MIBI scintigraphy was performed in 19 consecutive AIT patients at the moment of clinical diagnosis of hyperthyroidism. The results were compared to several clinical and biochemical data including TSH, fT4, fT3, urinary iodine excretion, thyroid ultrasonography and color flow Doppler sonography (CFDS), thyroid 99mTcO4 scintigraphy and radioiodine uptake.
Results: On the basis of clinical features, instrumental and laboratory data (excluding MIBI scintigraphy), response to therapy and hormonal follow-up, a final diagnosis of AIT I was reached in 6 cases, AIT II in 9 cases, while 4 patients had mixed forms of AIT. MIBI scintigraphy showed high and homogeneous thyroid uptake in 6/6 patients with AIT I, while no uptake was found in 9/9 patients with AIT II. The remaining 4 patients, finally classified as mixed AIT, showed in 2 cases a low and patchy uptake, while a rapid MIBI wash out was observed in the remaining 2 cases. Compared to all other imaging techniques (including CFDS), MIBI scintigraphy gave the best diagnostic discrimination of AIT I from AIT II, providing also further hints to identify mixed forms of AIT.
Conclusion: thyroid MIBI scintigraphy may be proposed as easy and high effective diagnostic tool for the differential diagnosis of AIT
The usefulness of 99mTc-sestaMIBI thyroid scan in the differential diagnosis and management of amiodarone-induced thyrotoxicosis
No full textBackground: Amiodarone-induced thyrotoxicosis (AIT) is caused by excessive hormone synthesis and release (AIT I) or a destructive process (AIT II). This differentiation has important therapeutic implications.
Purpose: To evaluate 99mTc-sestaMIBI (MIBI) thyroid scintigraphy in addition to other diagnostic tools in the diagnosis and management of AIT.
Subjects and methods: Thyroid 99mTcOK4 and 99mTc-MIBI scintigraphies were performed in 20 consecutive AIT patients, along with a series of biochemical and instrumental investigations (measurement of thyrotrophin, free thyroid hormones and thyroid autoantibodies; thyroid colour-flow Doppler sonography (CFDS) and thyroid radioiodine uptake (RAIU).
Results: On the basis of instrumental and laboratory data (excluding thyroid 99mTc-MIBI scintigraphy) and follow-up, AIT patients could be subdivided into six with AIT I, ten with AIT II and four with indefinite forms of AIT (AIT Ind). 99mTc-MIBI uptake results were normal/increased in all the six patients with AIT I and absent in all the ten patients with AIT II. The remaining four patients with AIT Ind showed low, patchy and persistent uptake in two cases and in the other two evident MIBI uptake followed by a rapid washout. MIBI scintigraphy was superior to all other diagnostic tools, including CFDS (suggestive of AIT I in three patients with AIT II and of AIT II in three with AIT Ind) and RAIU, which was measurable in all patients with AIT I, and also in four out of the ten with AIT II.
Conclusion: Thyroid MIBI scintigraphy may be proposed as an easy and highly effective tool for the differential diagnosis of different forms of AIT
Coexistent thyroid pathology may impair parathyroid localization in primary hyperparathyroidism: usefulness of PTH assay in FNAB fluid wash-out.
No full textPurpose: To assess the value of parathyroid hormone (PTH) assay in fine needle aspiration biopsy wash out fluid (FNA-PTH) to localize hyperfunctioning parathyroids (HP), in primary hyperparathyroidism (pHPT) associated to nodular thyroid diseases.
Subjects and Methods: A total of 58 lesions suspect for HP from 40 patients with pHPT associated to multinodular goiter (MNG) and/or Hashimoto's thyroiditis (HT) were considered. Sixteen HP (form 16 patients) unequivocally localized by sestaMIBI scintigraphy (MIBI) and neck ultrasound (US) (group I), were compared to 42 suspect lesions (from 24 patients) displaying uncertain parathyroid localization (group II). In all cases US, MIBI, FNA-PTH and FNA-cytology and were performed. FNA-PTH was considered indicative for HP when it exceeded the value of 103 pg/ml (i.e. three times the maximal level found in not-HP lesions).
Results: MIBI correctly identified all HP in group I patients, while a lower diagnostic accuracy (sensitivity 70 % , specificity 25 %) was observed in group II, due to the presence of both MIBI negative HP (more frequently observed in HT [6/9, 66,7%] vs MNG [6/31, 19.3%], p< 0.02) and MIBI positive thyroid nodules. In contrast, FNA-PTH correctly identified all HP (38 adenomas, 2 hyperplastic parathyroid, and 1 carcinoma) in both groups of patients, with 100% sensitivity and specificity. FNA-cytology, although 100% specific, showed low sensitivity (53.7%), with no differences between the two groups.
Conclusions: In pHPT coexistent thyroid pathology (particularly HT) may cause variable degree of mismatch between MIBI and US resulting in difficult HP localization. In these cases FNA-PTH resulted an accurate and safe tool to localize HP. However, due to its reported potential risks, this procedure may be advised only to patients with uncertain HP localization
Parathyroid hormone assay in neck nodules aspirate (PTH-FNAB) in primary hyperparathyroidism (PHP) with uncertain 99mTc-sesta-MIBI scintigraphy (MIBI)
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