1,721,023 research outputs found

    The Challenging Patient

    No full text
    In the past decade, coronary CT angiography (CCTA) has established itself as a robust imaging technique for the exclusion of coronary artery disease (CAD) in patients presenting with acute chest pain and moderate cardiovascular risk due to its high sensitivity and negative predictive value in detecting significant coronary artery stenosis. Noninvasive CCTA has become a reliable alternative to inva- sive angiography and, thanks to recent technical innova- tions, has raised its power from just a morphological evaluation to a more comprehensive morphological and functional assessment. Specifically, novel CT technological advancements such as CT myocardial perfusion imaging (CT-MPI) provide a reliable functional analysis of the heart capable of accurately presenting hemodynamically significant coronary artery stenosis. CCTA coupled with CT-MPI could raise CT as the stand-alone image modality for a com-prehensive evaluation of CAD and direct assessment of myo- cardial ischemia in a single examination. Technically speaking, CCTA presents a greater challenge and is more demanding than other CT applications due to the nature of its target, the continuously moving heart. Thus, higher spatial and temporal resolutions are mandatory for a proper visualization of small-caliber vessels such as cor- onary arteries. In addition, image acquisition should be syn- chronized with the patient’s electrocardiogram (ECG) in order to achieve optimal image quality. Due to its technical com- plexity, the accurate selection and preparation of the patient are mandatory for obtaining a high-level examination. Despite the continuous technological advances that have unleashed the diagnostic power of CCTA and allowed accu- rate diagnoses even in difficult clinical scenarios, some minor limitations should still be taken into account when performing CCTA examinations. The comprehensive defini- tion of a challenging patient embraces some clinical condi- tions that should be investigated in order to always guarantee a safe and accurate CT examination

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The 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 link
    We 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

    Reply

    No full text
    corecore