1,720,963 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
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
Feasibility of computed tomography cholangiography using Gd-EOB-DTPA: a phantom study
No full textPurpose: To assess the feasibility of computed tomography cholangiography
(CTCG) using an hepatobiliary contrast agent for magnetic resonance imaging
(Gd-EOB-DTPA).
Material and Methods: We built three CT phantoms including a
radiotransparent 2:1 scale representation of the extrahepatic and intrahepatic bile ducts up to the second order branches. By assuming standard contrast
pharmacokinetics in an adult male patient of 70 kg, we filled phantoms with
water and a volume of 4.05, 3.15 and 2.25 mL of 0.25 mmol/L concentrated
Gd-EOB-DTPA, respectively. Volumes corresponded to the expected dose
fraction (DF) of Gd-EOB-DTPA in the biliary tree given a i.v. dose to the patient
(DP) of 9.0, 7.0 and 5.0 mL, respectively. Phantoms were scanned with a 64-
row multidetector CT using a standardized protocol (120 kVp and 200-500
mA). We then performed a quantitative analysis by calculating the signal-tonoise
ratio (SNR) of the biliary tree over the phantom background.
Results: On visual analysis, the biliary tree phantoms appeared as
hyperattenuating, regardless of contrast DF/DP. On quantitative analysis, the
phantom with DF/DP = 3.15/7.0 mL, corresponding to the standard patient
dose, showed average SNR (6.51) similar to that of the 2.25/5.0 mL phantom
(SNR=6.45), although lower than the DF/DP = 4.05/9.0 mL phantom
(SNR=11.56).
Conclusion: In our model, a standard i.v. dose of Gd-EOB-DTPA determines
acceptable hyperattenuation of the biliary tree on CT
Apparent diffusion coefficient (ADC) in discriminating between solid benign and malignant focal liver lesions (FLLs) with diffusion-weighted imaging (DWI): comparison of ADC thresholding versus normalized ADC thresholding and lesion-to-liver ADC ratio
No full textPurpose: The purpose of this study was to compare the diagnostic performance
of three different methods of ADC estimation in differentiating solid benign and
malignant FLLs.
Material and Methods: We included forty-five patients with 75 FLLs detected
on a 1.5 T system, and proven to be malignant and benign in 55 and 20 cases,
respectively (cysts/haemangiomas excluded). During separate reading
sessions, two readers in consensus evaluated DWI images and the ADC map.
FLLs were assessed as benign or malignant: (a) according to the threshold
established by a receiver operating characteristic (ROC) analysis, without
(ADC-T) and with (ADC-TS) normalization for the spleen, respectively; (b) by
calculating the lesion-to-liver ADC ratio (ADC-R; cut-off <1). End-points for the
three methods were the positive- and negative-predictive value (PPV, NPV) for
malignancy and the area under the curve (AUC) values.
Results: ADC threshold for malignancy was 1.06 x10-3 mm2/sec for ADC-T
and 1.27 x10-3 mm2/sec for ADC-TS. ADC-T, ADC-TS and ADC-R showed
high PPV (89.2%, 84.6% and 78.1%, respectively), but low NPV (42.1%,
38.9% and 30.2%, respectively). AUCs of ADC-T (0.70) and ADC-TS (0.65)
were higher as compared to that of ADC-R (0.55), showing a significant
difference between ADC-T and ADC-R (p<0.01). Main source of false-negative
cases was hepatocarcinoma (22-30/55).
Conclusion: Normalizing FLLs ADC for the spleen or providing the ADC-R did not
improve the diagnostic performance of ADC-T, which is limited by a low NPV
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Evolution of bile-duct dilatation in liver-transplanted patients with biliary stricture: an MRC-based study.
No full textPurpose: To assess whether bile-duct dilatation is influenced by the type of biliary stricture and time from liver-transplantation in LTPs.
Methods and Materials: Eighty-five 3D-MRCs performed over a 2-years period on 54 LTPs with proven bile-duct strictures were retrospectively evaluated. Diameter was measured on thin source images at the common bile duct (CBD), right hepatic duct (RHD), left hepatic duct (LHD), anterior- and posterior-right hepatic ducts (aRHD,pRHD), left lateral and medial ducts (LL,LM). Presence of dilatation was assessed for peripheral ducts (2-mm treshold). Data were stratified according to the type of stricture (all types, anastomotic, ischaemic-like, and mixed) and compared: (i) between two groups based on the timing of MRC from liver transplantation (OLT) (within or after 1 year, respectively); (ii) within types of strictures.
Results: Except for the CBD and peripheral ducts, the biliary tree resulted slightly dilated within 1-year from OLT (2.9±1.4-4.7±3.1 mm), especially at LHD and pRHD (4.7±3.1 and 3.6±1.9 mm, respectively). A trend towards increase in diameter after 1-year characterized all biliary ducts, showing statistical significance for all types (p=0.0005-0.0351;t-test) and mixed-type (0.0002-0.0394;t-test) of strictures. Increase was homogeneous for all biliary ducts and types of stricture (mean=1.5±0.5 mm). Biliary dilatation occurred more frequently after 1-year in peripheral ducts (p0.05;ANOVA).
Conclusion: Upstream dilatation in LTPs with bile-duct stricture is higher in late post-liver-transplantation period, especially for the mixed-type. MRCP is optimal as a panoramic first-line imaging evaluation
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