1,721,013 research outputs found
A new approach to numerical solution of nonlinear Klein-Gordon equation
Get PDFA numerical method based on collocation points is developed to solve the nonlinear Klein-Gordon equations by using the Taylor matrix method. The method is applied to some test examples and the numerical results are compared with the exact solutions. The results reveal that the method is very effective, simple, and convenient. In addition, an error estimation of proposed method is presented. © 2013 Berna Bülbül and Mehmet Sezer
Numerical Solution of Duffing Equation by Using an Improved Taylor Matrix Method
Get PDFWe have suggested a numerical approach, which is based on an improved Taylor matrix method, for solving Duffing differential equations. The method is based on the approximation by the truncated Taylor series about center zero. Duffing equation and conditions are transformed into the matrix equations, which corresponds to a system of nonlinear algebraic equations with the unknown coefficients, via collocation points. Combining these matrix equations and then solving the system yield the unknown coefficients of the solution function. Numerical examples are included to demonstrate the validity and the applicability of the technique. The results show the efficiency and the accuracy of the present work. Also, the method can be easily applied to engineering and science problems
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
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
Farklı kök kanal patlarının sitotoksisite ve antimikrobiyal etkinlik yönünden karşılaştırılması
No full textBu çalışmanın amacı, kök kanal tedavilerinde kullanılan AH Plus, Tubli Seal EWT, EndoREZ, MTA Fillapex, Real Seal kök kanal dolgu patlarının L-929 hücre kültüründe MTT testi ile sitotoksik etkilerinin ve ayrıca Enterococcus faecalis üzerinde direkt temas testi ile antimikrobiyal etkilerinin incelenmesidir. Çalışmanın birinci bölümünde, 6 kuyucuklu plağın her bir kuyucuğuna farklı kök kanal dolgu patı 1 cm alanı kaplayacak şekilde yerleştirilmiştir. Örnekler üzerine DMEM ilave edilerek, 24, 48 ve 72 saat bekletilmiştir. Elde edilen ekstraksiyon sıvıları, L-929 hücre süspansiyonu içeren 96 kuyucuklu plakların her bir gözüne 100 l yerleştirilmiştir. 48 saatlik inkübasyondan sonra plaklardan ekstraksiyon sıvıları uzaklaştırılmış ve her bir göze 25 l MTT solüsyonu ilave edilerek 4 saat süre ile bekletilmiştir. Bu sürenin sonunda spektrofotometrede 570 nm'de absorbansları ölçülmüştür. Çalışmanın ikinci bölümünde, kök kanal dolgu patları karıştırılarak 96 kuyucuklu plakların yan duvarına yerleştirilmiş ve 10 ?l bakteriyel süspansiyon eklenerek, bakteri ve patın direkt temasını sağlamak için 1 saat beklenmiştir. Patın bulunduğu kuyucuklara taze besiyeri eklenmiş ve bu kuyucuklardan 15 ?l besiyeri alınarak sadece besiyeri bulunan kuyucuklara ilave edilmiştir. Bakteriyel büyüme, 18 saatlik zaman periyodunda ilk 6 saat ve son 6 saat her saatte bir spektrofotometre kullanılarak 620 nm'de ölçülmüştür. Mosmann'ın sınıflamasına göre AH Plus her 3 zaman diliminde de sitotoksisite göstermezken, Tubli Seal EWT, EndoREZ, MTA Fillapex ve Real Seal 24. ve 48. saatlerde orta, 72. saatte ise hafif derecede sitotoksisite göstermişlerdir. MTT testi sonuçlarına göre ise, 24, 48 ve 72 saatlik değerlendirmede hücre canlılık oranları bakımından AH Plus ve kontrol grubu arasında istatistiksel olarak anlamlı bir fark gözlenmezken (p>0,05), diğer kök kanal dolgu patları ve kontrol grubu arasında istatistiksel olarak anlamlı bir fark olduğu tespit edilmiştir (p<0,05). Kontrol grubuna ait hücre canlılık oranları Tubli Seal EWT, EndoREZ, MTA Fillapex ve Real Seal kök kanal dolgu patlarının hücre canlılık oranlarından anlamlı derecede daha yüksektir. Direkt temas testi sonuçlarına göre, Grup A (pat var)'da ilk 6 saatlik sürede Real Seal hariç diğer tüm kök kanal dolgu patları antimikrobiyal etki gösterirken, son 6 saatlik sürede EndoREZ, MTA Fillapex ve Real Seal antimikrobiyal etkilerini devam ettirmişlerdir. Tubli Seal EWT 14. saatte antimikrobiyal etkisini kaybetmeye başlamış, Real Seal antimikrobiyal etkinlik göstermemiştir. Grup B (pat yok)'de ilk 6 saatlik sürede bütün kök kanal dolgu patları antimikrobiyal etki gösterirken, son 6 saat tüm patlar antimikrobiyal etkilerini kaybetmişlerdir. Abstract The aim of this study was evaluate the cytotoxicity of root canal sealers AH Plus, Tubli Seal EWT, EndoREZ, MTA Fillapex and Real Seal on L-929 cells with the MTT assay and the antimicrobial effects on Enterococcus faecalis using the direct contact test. In the first part of this study, sealers were placed in six-well plate. Every sealers placed at the bottom of each well to cover an area of 1 cm diameter. Placed DMEM on samples for 24, 48 and 72 hours. 100 ?l of eluate was transferred to a 96- well plate containing L-929 cell suspension. After 48 hours incubation the extracts were removed from the wells, 25 ?l MTT solution was added to each well and waited for 4 hours. Subsequently, the spectrophotometric absorbance was measured at 570 nm using a spectrophotometer. In the second part of this study, sealers were mixed and placed on the side walls of 96-well plate well and 10 ?l bacterial suspensions were allowed to directly contact with the sealers for 1 hour. Fresh media were added to wells which including sealers and 15 ?l were transferred from this wells to another wells containing fresh medium. Bacterial growth was then measured using spectrophotometer at 620 nm first six and last six hours at one hour periods over 18 hours. According to Mosmann?s scala AH Plus was non-cytotoxic, Tubli Seal EWT, EndoREZ, MTA Fillapex and Real Seal had moderate cytotoxicity at 24 and 48 hour evaluation and slightly cytotoxicity at 72 hour evaluation. According to the MTT assay, in the rates of cell viability there was no statistically significant difference between AH Plus and control group at 24, 48 and 72-hour evaluation (p>0.05), but there was statistically significant difference between the other sealers and control group (p<0.05). The control group had significantly high rates of cell viability than Tubli Seal EWT, EndoREZ, MTA Fillapex and Real Seal. The results of the direct contact test showed that, in Grup A (paste present) at first six hours except Real Seal all sealers had antimicrobial effect, at last six hours AH Plus, EndoREZ and MTA Fillapex continue their antimicrobial effect, Tubli Seal EWT started to loose its antimicrobial effect at 14. hour and Real Seal had no antimicrobial effect. In Grup B (paste absense) at first six hours all sealers had antimicrobial effect, but they lost their antimicrobial effect at last six hours
Farklı kök kanal dolgu sistemleri kullanılarak doldurulan kök kanallarının homojenitelerinin karşılaştırılması
No full textBu çalışmanın amacı, üretan dimetakrilat rezin içerikli, cam iyonomer içerikli ve epoksi rezin içerikli kök kanal dolgu sistemleriyle doldurulan kanalların, homojenitelerinin, boşlukların tespitiyle, micro-ct kullanılarak karşılaştırılmasıdır. Çalışmamızda 80 adet yeni çekilmiş, insan daimi alt küçük azı dişi kullanıldı. Kök kanalları şekillendirildikten sonra, 20'şerli 4 gruba ayrıldı. İlk üç grup sırasıyla Epiphany-Resilon, EndoREZ ve ActiV GP kök kanal dolgu sistemleriyle üretici firma önerisi doğrultusunda, dördüncü grup ise AH Plus-güta-perka ile lateral kondenzasyon dolgu tekniği kullanılarak dolduruldu. Her diş micro-CT cihazı kullanılarak incelendi, iki boyutlu reconstrüksiyondan sonra her kökten koronal,orta ve apikalden 3'er tane olmak üzere toplam 9'ar adet horizontal kesit seçildi. Görüntüler Image J görüntü analiz programında analiz edilerek, kanal alanı, boşluk alanların büyüklüğü ve sayısı hesaplandı. Boşluk alanlar kanal alanının yüzdesi olarak hesaplandı ve elde edilen bulgular Kruskal Wallis H testi ve Mann Whitney U testleri ile istatistiksel olarak değerlendirildi. Bulgularımıza göre, EndoREZ grubunda tespit edilen boşluk alan büyüklüğü ve sayısı koronal üçlüde Epiphany-Resilon ve AH Plus gruplarından, orta üçlüde Epiphany-Resilon, ActiV GP ve AH Plus gruplarından, apikal üçlüde ise Epiphany-Resilon grubundan istatistiksel olarak anlamlı derecede fazladır (p<0,05). Diğer gruplar arasında boşluk alan büyüklüğü ve sayısı bakımından anlamlı bir fark bulunamamıştır (p>0,005), ancak boşluk alan büyüklüğüne ve sayısına ait en düşük ortalama değerler Epiphany-Resilon grubunda tespit edilmiştir. Tüm gruplara ait köklerin, apikal üçlülerindeki boşluk alan büyüklüğü ve sayısı, koronal ve orta üçlülerinden istatistiksel olarak anlamlı derecede azdır (p<0,05). Koronal ve orta üçlüler arasında anlamlı bir fark bulunamamıştır (p>0,05), ancak boşluk alan büyüklüğüne ve sayısına ait en yüksek ortalama değerler, Epiphnay-Resilon grubu hariç köklerin orta üçlülerinde tespit edilmiştir.Abstract The aim of this study was to compare the homogeneity of root canals obturated with urethan dimetacrylate based, glass ionomer based and epoxy resin based root canal filling systems, by detecting voids with using micro-CT. 80 freshly extracted permanent human mandibular premolar teeth were used in this study. After the preparation of the root canals, the teeth were randomly divided into 4 groups, consisting 20 teeth of each. The first three group were obturated with Epiphany-Resilon, EndoREZ and ActiV GP root canal filling systems respectively, according to manufacturer?s recommendations and the fourth group was obturated with AH Plus-güta-perka by using lateral compaction technique. Every tooth was examined using micro-CT and after 2D reconstruction, total of 9 horizontal sections were chosen from each root, from coronal, middle and apical thirds. Images were analysed with Image J software and area of the canal, area of voids and number of voids for each section were evaluated. Area of voids was calculated as a percentage of the canal area in the sections. The results were analysed statistically using Kruskal Wallis H Test and Mann Whitney U Test. According to datas of our study, area of voids and number of voids detected in EndoREZ group were statistically significantly higher than Epiphany-Resilon and AH Plus-güta-perka groups at the coronal third, Epiphany-Resilon, ActiV GP and AH Plus-güta-perka groups at the middle third and Epiphany-Resilon group at the apical third (p<0,05). There were no significant differences found among the other three groups (p>0,05) with respect to area of voids and number of voids, but the lowest mean of area of voids and number of voids were recorded in Epiphany-Resilon group. In all study groups, area of voids and number of voids at the apical thirds were statistically significantly lower than the coronal and middle thirds (p<0,05). There were no significant differences between the coronal and middle thirds (p>0,05) but the highest mean of area of voids and number of voids were recorded at the middle thirds of the roots, except Epiphany-Resilon group
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