1,721,018 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
MONITORIZATION OF PATULIN AND HYDROXYMETHYLFURFURAL IN FRUIT JUICES AND COMMERCIAL FRUITY BABY FOODS BY AN HPLC-DAD METHOD
No full textPatulin as a mycotoxin and hydroxymethylfurfural as a chemicals decomposition product are the toxic compounds that are suspected to be cytotoxic and carcinogenic. The aim of this study was to develop a fast, convenient and reliable high-performance liquid chromatography (HPLC) method for the simultaneous analysis of patulin and hydroxymethylfurfural in 86 commercially available fruity baby foods (n=18) and fruit juices (n=68). Fruit juice or baby food sample (5 mL) was extracted with 10 mL ethyl acetate twice time and treated with 2% Na2CO3 solution. Afterwards, the extract was treated with 1 gr Na2SO4 and was filtered with Whatman (R) filter paper and the addition of 0.25 mL acetic acid onto obtained extract solution, it was filtered with 0.45 mu m disc filter and after the evaporation step, dissolution which was rebuilt with 500 mu L acidified water, applied to the HPLC as 20 mu L. The separation was carried out by the C-18 column (4.6x250 mm, 5 mu m i.d.) and quantitated with diode array detector (DAD) set at 276 nm. Recovery was >= 94.9%. Limit of quantification (LOQ) was 0.6 ng/mL for patulin and 0.3 mu g/mL for hydroxymethylfurfural HMF. The average level of patulin and hydroxymethylfurfural concentration were determined as 38.24 ng/mL +/- 39.64 and 7.24 mu g/mL +/- 7.68 in all samples. Also, unpermitted concentrations of patulin and hydroxymethylfurfural in the samples were detected as 27.9% and 16.7%, respectively. The detected concentration of PAT was higher in the fruit juices (p<0.001) than baby food samples.Scientific Research Projects Unit of Sivas Cumhuriyet University [ECZ038]This work is supported by the Scientific Research Projects Unit of Sivas Cumhuriyet University under the project number ECZ038
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
Benzen Toluen Etil Benzen Xylene BTEX Exposures Pharmacokinetics Health Effects and Determination Methods
No full textSildenafil düzeylerinin, pulmoner arteriyal hipertansiyon hasta plazmalarında kromatografik yöntemle belirlenmesi ve 'bitkisel kökenli' ürünlerde ilegal varlığının araştırılması
No full textSildenafil, fosfodiesteraz tip5 enziminin seçici ve potent bir inhibitörü olup pulmoner hipertansiyon hastalığının (PAH) ve erektil fonksiyon bozukluğunun idame tedavisinde kullanılmaktadır. Bu çalışmada sildenafilin insan plazması ile piyasada "Bitkisel Ürün" ifadesiyle satılmakta olan ürünlerin içeriğindeki varlığını ve düzeyini araştırmak amacıyla yüksek performanslı sıvı kromatografi (HPLC) ile analiz yöntemi geliştirildi. Bu amaçla özgün, güvenilir, hassas bir metot oluşturuldu ve ilgili test uygulamaları yapılarak metot valide edildi. Plazmadan sildenafil (1mL) izole edilmeden önce içeriğine iç standart olarak verapamil ve 200µL hacimde 1M'lık NaOH eklenerek ortam alkali hale dönüştürülmüştür. Ardından ekstraksiyon işlemi için karışıma 3mL etil asetat konulmuştur. Ekstraksiyon sonrası organik çözücü, azot altında, 40°C'de ve sabit akışta tam kuruluğa kadar uçurulmuş, ardından 200µL mobil fazda yeniden oluşturulmuştur. Kromatografik analiz inertsil C18 ters faz kolon ile 0,8mL/dak akış hızında, %60 asetonitril %40 amonyum asetat tamponlu mobil faz sistemi kullanılarak, 100µL enjeksiyon hacmi ile gerçekleştirildi. Analiz süresi 9 dakika idi. Ekstraksiyon ürünlerinin analizleri ultraviyole dedektör (UV) ile 225nm'de yapılmıştır. Sildenafil ve verapamil'in retansiyon zamanları sırasıyla 6,76 ve 8,01 idi. Doğrusallık (linearity) plazmada 7,16–716ng/mL aralığında incelenmiştir. Gözlenebilme sınırı (LOD) 0,64ng/mL, tayin sınırı (LOQ) ise 1,93ng/mL idi. Metodun doğruluğu (accuracy), gün içinde (%RE) 6,47 ile 5,73, günler arasında ise -7,39 ile 6,45 aralığındadır. Metodun kesinliği (precision) gün içinde (%RSD) 1,74–5,68, günler arasında ise 2,58–6,23 aralığındadır. İncelenen 6 PAH hastasına ait sildenafil plazma dağılımı 27,05–2055,43ng/mL'dir. Sildenafil düzeyleri 914,25±924,75(Ort.±SD) şeklindedir. Piyasada "bitkisel" ifadesiyle satılmakta olan 8 ürünün içeriğinde sildenafil araştırılmıştır. 4 örnekte sildenafil belirlenmiştir. Bu örneklerdeki sildenafil miktarları 10,55-621,28ng/mL aralığında bulunmuş, 176,65±297,32(Ort.±SD) olarak gözlenmiştir
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