1,720,957 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Solid Renal Tumors Isoenhancing to Kidneys on Contrast-Enhanced Sonography: Differentiation From Pseudomasses
No full textOBJECTIVES:
To estimate the prevalence of solid renal tumors isoenhancing to kidneys in all vascular phases on contrast-enhanced sonography and to investigate whether they can be differentiated from pseudomasses.
METHODS:
A computer search of the databases of 3 institutions identified 31 patients with pseudomasses and 380 patients with solid tumors investigated with contrast-enhanced sonography. Nineteen of 380 (5%) patients had tumors isoenhancing in all phases. Images and clips of these 19 tumors and the 31 pseudomasses were blindly assessed by 2 radiologists. They were asked to differentiate tumors from pseudomasses based on echogenicity, vascular architecture, and the presence of the medulla.
RESULTS:
Isoenhancing tumors were clear cell carcinomas (n = 7), angiomyolipomas (n = 3), papillary tumors (n = 3), metastasis (n = 1), and oncocytoma (n = 1). In the 4 nonoperated tumors, the diagnosis was confirmed by progression during the follow-up. There were 3 markedly hyperechoic, 11 mildly hypo/hyperechoic, and 5 isoechoic masses. Most pseudomasses were isoechoic to kidneys (23 of 31), with the medulla identified in 22 of 31 and 15 of 31 by radiologists 1 and 2, respectively. One and 2 pseudomasses were considered tumors by radiologists 1 and 2, respectively. One isoechoic isoenhancing tumor was not identified on contrast-enhanced sonography. Isoenhancing tumors in all phases were differentiated from pseudomasses by combining grayscale and contrast-enhanced sonography (areas under the receiver operating characteristic curve, 0.997 for reader 1; 0.969 for reader 2), with very good inter-reader agreement (weighted κ = 0.81).
CONCLUSIONS:
In our retrospective study, 5% of solid renal lesions were isoenhancing to kidneys in all phases. Differentiation from pseudomasses was possible by looking at baseline sonographic features and vascular characteristics
Contrast-enhanced ultrasound for characterizing renal masses
No full textOn cross-sectional imaging studies performed for other indications, incidental discovery of renal lesions is not uncommon. In daily use, grey-scale ultrasonography (US) and conventional Doppler modes are often the modality of choice for the initial assessment. While simple cysts are fully characterized with US, other lesions require further characterization, which is traditionally obtained by multiphase imaging, such as contrast-enhanced CT and MRI. Contrast-enhanced ultrasound (CEUS) has become a powerful additional tool for imaging renal lesions. With its lack of nephrotoxicity, the absence of ionizing radiation, and the ability to evaluate the enhancement pattern of renal lesions quickly and in real- time, CEUS has unique advantages over traditional modes. Established applications are differentiation between solid tumours, pseudolesions, and complex cysts; characterization of complex cysts with different malignant potential, and evaluation of tumor ablation. Microbubble contrast agents are safe. Adverse reactions are rare. This article provides an overview of the current clinical applications of CEUS in characterizing renal masses, discussing advantages and limitations. The aim is to provide the framework for sonologists to make informed decisions regarding this emerging imaging test in appropriate circumstances
Focal testicular lesions. Multiparametric us features and association with histopathology
No full textNTRODUCTION AND OBJECTIVES:
Testicular cancer represents the most common solid tumors in young men and malignant germ cell tumors constitute the majority of these masses. Orchiectomy is the treatment of choice for intratesticular masses. However, it is important to recognize those benign conditions for which orchiectomy is unwarranted because approximately 5-10% of all testicular masses are postoperatively identified as benign testicular lesions. Ultrasound features of solid scrotal tumors are often non-specific. US, however, identifies the lesion in the largest number of cases. Here, we evaluate the histopatologic features which determine echogenicity, echotexture, stiffness, and vascularity of different testicular masses.
METHODS:
98 testicular lesions investigated with colour Doppler US for which histological specimens were available for review were enclosed. 47 lesions had also CEUS, 34 elastography. Imaging features were correlated with histological characteristics.
RESULTS:
Most testicular cancers were hypervascular at colour Doppler interrogation and with increased consistency at elastography. 6/22 hypovascular lesions with small vessels at colour Doppler interrogation were hypervascular at CEUS. Seminomas presented with lower echogenicity compared to other cancers, mixed tumors were heterogeneous. Irrespective of histotype, abundance of stroma was the main factor determining increased echogenicity. Other factors were hyalization, interleaved necrotic areas and tumor nests, athrophic changes of the surrounding parenchyma. Heterogeous appearance was observed in presence of different histotypes, calcifications, necrotic or fibrotic areas. Lesions were avascular at colour Doppler interrogation if vessels were lacking or were very small. In the latter case, they were vascularized at CEUS. Lesions with abundant stroma were hard at elastography, while necrotic changes caused soft or mixed appearance
CONCLUSIONS:
The different histological features of testicular lesions determine their sonographic appearance. US is highly sensitive for detection of testicular lesions, but specificity is low.The different US modes, if taken individually, are non-specific but if used together improve lesion characterization.
Preoperative imaging and correct characterization of focal testicular lesions play a quite important role in guiding the surgical approach to these patients allowing the identification of testicular lesions amenable to treatment with testicular-sparing surger
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Multiparametric US for scrotal diseases
Full text linkMultiparametric US is increasingly recognized as a valuable problem-solving technique in scrotal pathologies. Compared to conventional Doppler modes, contrast-enhanced ultrasonography (CEUS) has higher sensitivity in assessing the presence or absence of flows, and to improve differentiation between poorly vascularized tumors and non-neoplastic, avascular lesions. Characterization of benign and malignant complex cysts is improved. In trauma patients, CEUS can help evaluating the viability of testicular parenchyma. In patients with severe epididymo-orchitis, it allows unequivocal assessment of post-inflammatory ischemic changes and abscess formation. CEUS does not add significantly to conventional Doppler modes in spermatic cord torsion. Attempt of differentiating benign and malignant tumors remains a research tool. In the clinical practice, elastography has a limited role for tumor characterization. The majority of malignant tumors are stiff at elastography, but they may display soft areas, or appear globally soft. A quantitative evaluation of testicular stiffness is feasible using shear-wave elastography. Potential clinical applications for elastographic modes could include work-up of infertile patients
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