1,721,007 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Comparative study on the morphology, palynology and essential oil composition of three trigonella L. species (Fabaceae) from Iran
No full textTrigonella L. is one of the important genera of the family Fabaceae, many species of which have nutritional and medicinal properties. In this investigation, morphological characters related to habit and pollen grain of three Trigonella species i.e., T. disperma, T. subenervis and T. aphanoneura were studied. Oils from the aerial parts of two species were investigated by GC and GC/MS methods and compared with T. disperma, which had been studied in advance. T. subenervis represented oils rich in spathulenol (15.1%). It also contained a small amount of germacrene D (0.6%). T. aphanoneura also represented oils rich in spathulenol (10.4%). The amount of four compounds in this species was ≤1%, and n-octyl acetate was the lowest component in quantity. According what we found out, phytochemical and morphological data could clarify the relationships among the Trigonellaspecies better than pollen morphological dat
Green synthesis of silver nanoparticles using aqueous seed extract of Cuminum cyminum L. and evaluation of their biological activities
No full textIntroduction: There are many reports on the application of medicinal plants in traditional medicine, as well as numerous applications of metallic nanoparticles in different biomedical fields. Plant extract mediated green synthesis of nanoparticles and investigations on their therapeutic effects are new concepts. The medicinal plant of Cuminum cyminum L. includes a wide range of secondary metabolites with a high reducing power, which can be used for green biosynthesis of silver nanoparticles. The main aims of this study were phytochemical analysis of seed aqueous extract of Cuminum cyminum, biosynthesis of silver nanoparticles using this extract, the achievement of optimization condition for the synthesis of silver nanoparticles, and assessment of biological activaties of both the extract and the synthesized nanoparticles.
Materials & Methods: Total phenol and flavonoid, reducing sugar, starch, and ascorbic acid contents were measured by Folin-Ciocalteo, aluminum chloride, dinitrosalicylic acid, anthrone, and dinitrophenyl hydrazine reagents, respectively. The Ag+ ions reduction and characterization of silver nanoparticles were assessed by UV-Visible spectrophotometry, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Antioxidant activity of the samples was screened by DPPH free radical scavenging. Antibacterial activity of the samples was also evaluated against four gram-positive and -negative bacteria namely, Bacillus cereus (PTCC 1247), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 35218), and Pseudomonas aeruginosa (ATCC 27853) by disc diffusion method. In addition, antifungal activity was assessed against Fusarium oxysporum.
Findings: The indings indicated that the seed extract contained the high amounts of total phenolic and flavonoidic compositions, as well as sugar, starch, and ascorbic acid. Different analyses showed that the mean size of the synthesized nanoparticles was 5-45 nm in the optimal condition. The samples had proper antioxidant potential (IC50=1.35-1.67 mg/ml) and the extract in combination with silver nanoparticles represented synergistic effect in DPPH free radical scavenging (IC50=1.35 mg/ml). In addition, the investiogated samples had a good antibacterial activity against some of tested bacteria and also antifungal activity against Fusarium oxysporum.
Discussion & Conclusions: It seems that the secondary metabolites of Cuminum cyminum have good potential for the reduction and stabilization of the synthesized Ag nanoparticles. Both the seed extract and synthesized nanoparticles using this extract have considerable biological activities and may be used in antioxidant nutrient production or medicinal supplements in future
Antioxidant Activity, Total Phenolic and Flavonoid Contents of Three Onobrychis Species from Iran
No full textBackground: Plant phenolic compounds are a main group of plant natural products and flavonoids are the largest and best studied natural phenols. These substances possess a series of biological properties and act on biological systems as antioxidants. In present research, the aim is to determine in vitro total phenolics content and antioxidant activity of the methanolic extracts of three Onobrychis species belonging to the family Fabaceae, namely O. sosnovskyi Grossh., O. viciifolia Scop. and O. melanotricha Boiss. Furthermore, an attempt was made to identify any correlations between total phenolic content of the extracts with their antioxidant activities Methods: Total phenol and flavonoid contents of the extracts were determined by Folin-Ciocalteu and aluminum chloride methods, respectively. Antioxidant activity was evaluated by three different test systems, namely 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging (DPPH), metal-chelation activity and ß-carotene/linoleic acid model. Results: Results indicated that O. viciifolia extract contains the highest total phenolic content (10.38 ± 0.33mg GAE/g of dry extract). However, the species are not remarkable different (P 0.55 to 0.98). Conclusion: Our results showed that the examined Onobrychis extracts represent strong antioxidant activity; hence, they can be suggested as antioxidant agents for special use in future
In Vitro Evaluation of Phenolics Content, Antioxidant and Antimicrobial Activities of Three Centaurea L. Species from Iran
No full textIn Vitro Evaluation of Phenolics Content, Antioxidant and Antimicrobial Activities of Three Centaurea L. Species from Iran
No full textBackground: Members of the genus Centaurea L. (Astraceae) are used in some countries for betterment of various ailments in the popular medicine. The main group of secondary metabolites in plants are phenolic compounds and flavonoids which are the main subset of phenolic compounds, possess a lot of biological properties such as antioxidant activity. The aim of present research is to determine in vitro total phenol and flavonoid contents, antioxidant potency and also antibacterial activity of the methanolic extracts of capitulla and aerial parts of three Centaurea species, namely C. sosnovsky Grossh., C. irritans Wagenitz and C. kandavanesis Wagenitz. In addition, any relationships between the phenolics content and their antioxidant properties were discussed. Methods: To determine total phenol and flavonoid contents of the methanolic extracts, Folin-Ciocalteu and aluminum chloride methods were used, respectively. To evaluate antioxidant activity three different test systems, namely 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging (DPPH), Cu-chelating and ß-carotene/linoleic acid bleaching were used. In addition, disc diffusion method was used to assess antibacterial activity of the extracts against 6 gram positive and negative bacteria. Results: Results indicated that the highest total phenol content (98.91 ± 1.87mg GAE/g of dry extract) represented by the aerial part extract of C. kandavanensis. The highest total flavonoid content (5.382 ± 0.231mg GAE/g of dry extract) and also DPPH radical scavenging activity (IC50; 0.20 ± 2.02 mg/ml) were exhibited by the capitulla extract of C. sosnovsky. However, the aerial part extract of C. irritans had the most potency for β-carotene bleaching (74.74%) among the studied samples. In addition, the extracts had acceptable antibacterial activity against both gram-positive and gram-negative bacteria tested. Conclusion: Overall, high content of phenolic compounds and proper antioxidant activity of the examined Centaurea extracts may suggest them as potent antioxidants for special use in future
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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