1,721,014 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
Biological effects of serum immunoglobulins from scleroderma patients on human pulmonary artery smooth muscle cells. Role of NOX4 and ROS
No full textAppropriate 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
Determination of Zeranol and b-zearalanol in Calf Urine by Immunoaffinity Extraction and Gas-Chromatography-Mass Spectrometry after Repeated Administration of Zeranol
No full textA method for the determination of zeranol and its metabolite beta-zearalanol in bovine urine is described. It has been applied to samples from calves given multiple subcutaneous doses of zeranol. Samples were extracted with immunoaffinity columns containing antibodies raised against zeranol and were analysed by gas chromatography-mass spectrometry. The immunoaffinity columns were prepared by coupling immunoglobulin G fractions obtained from rabbit antisera with a Sepharose matrix. The immunizing agent was carboxybutylzeranol coupled to bovine serum albumin. Gas chromatography-mass spectrometry was performed in the negative-ion chemical ionization mode, after derivatization of the compounds to their pentafluorobenzyl ethers, and allowed detection of analytes with a sensitivity of 0.01 ppb in spiked urine. The derivatization method and the gas chromatographic determination were also applied to the similar compounds zearalanone, zearalenone and beta-zearalenol. A synthesis of dideuterated zeranol and beta-zearalanol by isotopic exchange is described. These deuterated analogues had an isotopic purity of more than 99% and were used for quantitation of zeranol and beta-zearalanol by isotope dilution mass spectrometry. The recoveries of zeranol and beta-zearalanol, using the immunoaffinity columns, were determined after extraction from spiked urine and were 84 and 64%, respectively. The urines of treated calves were collected for several days after treatments and were analysed after hydrolysis with beta-glucuronidase and arylsulphatase. The samples showed variable but generally decreasing concentrations of zeranol and beta-zearalanol. The levels of beta-zearalanol ranged from < 0.01 to 98 ppb and were 1.2-3.2 times higher than those of zeranol
Metabolic Responses of Plants to Climate-Induced Stress: A Mass Spectrometry Investigation
Full text linkIn the past decade, the increasing global temperature caused by climate change has significantly impacted ecosystems, exposing them to various abiotic stressors, such as drought and salinity, which can alter plant physiology. In response to these abiotic stresses, plants can modify the levels of primary and secondary metabolites and hormones. In this study, we examined the impact of three climate change-related stressors-drought, altered salinity conditions, and acidified watering-on the metabolism of Lepidium sativum, using a metabolomic approach based on high-resolution mass spectrometry. MS and MS/MS spectra were analyzed with the Compound Discoverer software for metabolite identification and statistical analysis, while MetaboAnalyst was employed for pathway analysis. Plants exposed to drought stress exhibited the most significant metabolic alterations, with 36 altered metabolites in leaves and 45 in stems. In contrast, plants subjected to salinity stress showed changes in 16 metabolites in leaves and 30 in stems. Finally, plants irrigated with acidified water (pH 3) displayed the fewest altered metabolites, with only 6 in leaves and 2 in stems. The reduced impact of acidified water may be attributed to the soil's buffering capacity, which could have mitigated the effects of the acidified water. Overall, this study assesses how climate change impacts plant metabolism, paving the way for future research aimed at understanding plant adaptation to climate change, with potential implications for botany, agriculture, and human health
Methodological approaches for studying pharmaceuticals in the environment by comparing predicted and measured concentrations in River Po, Italy
No full textA predictive approach seems useful to study human and veterinary pharmaceuticals in the environment and provide an idea of overall levels of contamination, so as to restrict monitoring to those molecules which are most likely to represent possible environmental contaminants. Predicted environmental concentrations (PECs) can be calculated by a mass balance approach, while a recent proposal from the European Agency for the Evaluation of Medicinal Products (EMEA) suggests an alternative method for calculating PEC for each pharmaceutical and then focusing further work on molecules with high PEC values. We used the results of monitoring campaigns on the River Po, in Northern Italy, to assess the accuracy of predictive models with measured environmental concentrations (MECs). The comparison indicated that in some cases a refined PEC value can provide a good approximation of the MEC. In other cases PECs substantially differed from the MECs, particularly when there were not enough data to estimate the environmental fate of the molecule. Predictive models might therefore be useful for studying pharmaceuticals in the environment, providing enough experimental data is available on the environmental fate of the molecules
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