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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
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
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
Confronto fra tre metodi di quantificazione del Coefficiente di Diffusione Apparente (ADC) nella differenziazione fra lesioni focali epatiche (LFE) solide benigne e maligne
No full textAccuracy of visual analysis vs. apparent diffusion coefficient quantification in differentiating solid benign and malignant focal liver lesions with diffusion-weighted imaging.
No full textPURPOSE: The authors compared the accuracy of diffusion-weighted imaging (DWI) visual analysis (VA) vs. apparent diffusion coefficient quantification (ADC-Q) in assessing malignancy of solid focal liver lesions (FLLs).
MATERIALS AND METHODS: Using a 1.5-T system, two radiologists retrospectively assessed as benign or malignant 50 solid FLLs: (a) by VA of signal intensity on DWI images at b=800 s/mm(2) and ADC map; (b) by quantifying lesion ADC. Reference standard included histology or follow-up confirmation of diagnosis by a consensus panel. Receiver operating characteristic (ROC) curve analysis was performed. RESULTS BECAUSE OF 20 FALSE-NEGATIVE HEPATOCELLULAR CARCINOMAS, VA SHOWED LOWER ACCURACY THAN ADC-Q (52.0% VS. 68.0%). HOWEVER, STRATIFIED ACCURACY FOR METASTASES WAS HIGHER WITH VA (75.0 VS. 66%). ADC AND SIGNAL FEATURES OF MALIGNANT AND BENIGN FLLS WERE FOUND TO LARGELY OVERLAP:
CONCLUSIONS: VA performed worse than ADC-Q for hepatocellular carcinoma and better for metastases. Overall, the accuracy of both methods was limited because of the overlap in visual appearance and ADC values between solid benign and malignant FLLs
Prevalenza dell'effetto T2-shine-through nelle immagini pesate in Diffusione (DW) nello studio delle lesioni focali epatiche: uno studio mediante mappe ADC esponenziali
No full textAppropriate 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
Differential contribution ov visual analysis (VA) and apparent diffusion coefficient quantification (ADC-Q) in assessing solid focal liver lesions with diffusion-weighted imaging (DWI).
No full textConfronto tra le mappe ADC convenzionali ed esponenziali nell'analisi visiva delle lesioni focali epatiche con imaging pesato in Diffusione
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