1,720,994 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
Which ratio should be adopted to evaluate the urinary excretion of testosterone and epitestosterone in veal calves?
No full text- Control of the illicit use of endogenous hormones in meat producing animals requires a detailed knowledge of both the metabolism of endogenous hormones and their physiological profiles in each species. Nowadays current approaches in cattle do not involve the determination of the absolute urinary concentration of endogenous hormones because no validated physiological levels are recognised; the same is true when the ratio between metabolites is considered, as applied for testosterone (T) and epitestosterone (E) in athletes (1). In man, urinary epitestosterone has attracted the attention as a reference substance in the doping control of testosterone abuse. The nearly constant urinary ratio of T to E (T/E) in adults became the basis of the method of detection of exogenously administered testosterone, since in humans epitestosterone does not originate from exogenous testosterone in significant amounts (2). Data from literature (2,3,4) reported that in cattle epitestosterone is a metabolite of testosterone probably produced in liver and blood by hydroxysteroid-oxido-reductase enzymes via androstenedione. Aim of the study was a preliminary approach to assess physiological concentrations of T and E in urine of veal calves, and to evaluate which urinary ratio could be useful to indicate hormone treatments in calves.
- The results reported showed that, despite the large variations of T and E concentrations in urine collected from veal calves, the physiological excretion of E was about ten times greater than T, and E excretion tends to decrease with increased age, as reported in young and adult men (2). Since in men urine concentrations of E and T are quite similar, and the excretion of E remained rather constant when exogenous T was administered; a cut-off value for T/E in urine was established for doping control (5). In a previous paper we applied the T/E ratio approach to urine of veal calves, but the influence of treatment was masked and no significant difference were observed between treated and control calves (6). Now, our recent data, confirmed that repeated treatments with natural hormone could cause a time-course reduction of urinary E as already reported (3, 7); applying the E/T ratio, the reduction of E urinary excretion was confirmed in Testosterone treated (A) but not in Boldenone treated calves (B and C)
Determination of tylosin residues in pig tissues using high-performance liquid chromatography
No full textIn accordance with the maximum residue limit of 100 micrograms kg-1 established by EU legislation, a simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the measurement of tylosin residues in pig tissues (fat, kidney, liver and muscle). Tylosin, a macrolide antibiotic, is extracted with water-methanol and cleaned-up by solid-phase extraction (SPE) on cation-exchange cartridges using methanol elution. Tylosin was determined by reversed-phase HPLC with UV detection at 280 nm and the mean recovery from pig tissues fortified in the range 50-200 micrograms kg-1 was 70-85%, with intra- and inter-day RSDs in the ranges 3.4-9.1 and 3.9-10.1% respectively
The urinary ratio of testosterone to epitetosterone: A good marker of illegal treatment also in cattle?
No full textThe authors evaluated the suitability of the testosterone: epitestosterone ratio, in calf urine, as a tool to detect the abuse of hormone treatments in food production species
Accuracy in naturally occurring anabolic steroid assays in cattle and first approach to quality control in Italy.
No full textThis study assessed the accuracy of 16 commercial and three self-produced kits and drew the basis for using an external quality control (EQC) system. The commercial kits were mainly developed for blood sex steroid determination in humans but also have been used in cattle. Parallelism, recovery and precision tests were performed for progesterone (P4), testosterone (T) and oestradiol (E2) assays. Moreover, anonymous QC samples were sent to be analysed to some Italian laboratories. All kits showed a fair degree of parallelism (P 10%. Moreover, the laboratories participating in the EQC produced statistically different (P < 0.05) results, particularly for high and medium concentrations. In conclusion, the use of commercial kits for screening naturally occurring sex steroid concentrations in cattle blood, in the case of suspected illegal treatments, requires preventive validation procedures and the development of an opportune EQC system
In vitro metabolism of Clenbuterol and Bromobuterol using microsomes from swine liver
No full text1. Clenbuterol (CBL) and bromobuterol (BBL) were both extensively metabolized by hepatic microsomes of swine to only one polar metabolite which was separated by hplc and purified to perform mass analysis. 2. LC-MIS analysis by direct infusion into an ion trap system and after reverse-phase chromatograpy into a triple quadrupole system showed that the metabolites were the hydroxylamine-derivatives of CBL and BBL. GC-MS analysis by the CI and EI modes confirmed that the hydroxyl group was bound to the aniline nitrogen. The chemical instability of those metabolites probably as a consequence of spontaneous oxidation and reduction gave rise during the analysis to the corresponding nitroso and nitro derivatives, together with the original compound. 3. Thermal inactivation and CO complex formation were used selectively to inactivate flavin monooxygenase and cytochrome P450, respectively. Both inactivation procedures significantly reduced the formation of the hydroxyl metabolite
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