1,720,963 research outputs found
Single breath diffusing capacity for carbon monoxide: Effects of adjustment for inspired volume dead space, carbon dioxide, hemoglobin and carboxyhemoglobin
No full textIn order to assess the additive effects of taking into account dead space volume (V-D), carbon dioxide, hemoglobin (Hb) and carboxyhemoglobin on computation of single breath carbon monoxide diffusing capacity (D(L)COsb), we sequentially applied all the corrections recommended by the 1987 American Thoracic Society (ATS) document on D(L)COsb standardization. We used data from 739 men (333 nonsmokers and 406 current smokers) and 475 women (403 nonsmokers and 72 current smokers) who underwent measurement of D(L)COsb in the decade 1985-1994 at the Lung Function Laboratory of our institute. With respect to the unadjusted D(L)COsb value, significant small differences were found for all the corrected formulas, ranging from -0.18 to 1.48 ml/min/mm Hg in men and from -0.24 to 1.57 ml/min/mm Hg in women. After computing the percent change of D(L)COsb [(unadjusted-adjusted value) x 100/unadjusted value], we observed that the correction for V-D caused an underestimation of D(L)COsb of about 5.8% in men and 7.7% in women. However, when all the corrections were considered, these figures decreased to about 0.9% in males and 2.9% in females. Regarding specifically the correction for Hb, the adjusted value was slightly lower in men, while it was somewhat higher in women, with respect to the unadjusted D(L)COsb. In conclusion, the corrections suggested by ATS in the computation of D(L)COsb, when considered altogether, seem to account for a limited proportion of test variability in usual clinical conditions, especially in males
Nonuniformity of the transmural distribution of coronary blood flow during the cardiac cycle. In vivo documentation by contrast echocardiography
No full textCharacterization of myocardial tissue in patients undergoing maintainance hemodialysis by quantitative echocardiography
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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
ECHOCARDIOGRAPHIC QUANTITATIVE TEXTURE ANALYSIS OF TISSUE ACOUSTIC PROPERTIES OF FRESH VERSUS ORGANIZED VENTRICULAR THROMBI
No full textThe age of a thrombus can be important clinical information in identifying patients at high risk for embolism, but recognizing the age of thrombi is difficult using only clinical data or a qualitative analysis of two-dimensional echocardiograms. We hypothesize that the quantitative analysis of image texture in two-dimensional echocardiograms would be an accurate method for in vivo differentiation of fresh from old ventricular thrombi. To test this hypothesis, we retrospectively evaluated two-dimensional echocardiographic images of cardiac thrombi detected in patients within the 1st week and at 6 months after an acute myocardial infarction with quantitative texture analysis. Of the quantitative texture measures of the first order, mean gray level, skewness, and kurtosis overlapped between fresh and old thrombi, but uniformity was significantly higher in older thrombi (0.036 +/- 0.008 for fresh vs 0.042 +/- 0.008 for old, P < 0.05). Of the second-order measures, entropy was significantly higher in fresh than in old thrombi (4.36 +/- 0.05 vs 4.58 +/- 0.05, P < 0.05), and angular second moment, correlation, and contrast overlapped. In conclusion, computerized quantitative texture analysis can help to differentiate fresh from old ventricular thrombi: old thrombi are characterized by a decrease in heterogeneity, which can be quantified by this technique
2-DIMENSIONAL ECHOCARDIOGRAPHY IN MYOCARDIAL AMYLOIDOSIS
No full textTwo-dimensional echocardiography is the best means of identifying early cardiac amyloid infiltration and gauging its subsequent progression. The early asymptomatic phase is characterized on echocardiography by a mild-to-moderate increase in left ventricular and/or right ventricular wall thicknesses. The distinctive combination of low electrocardiography voltage and increase in left ventricular mass on the echocardiogram, both compatible with substantial amyloid infiltration, is valuable in diagnosis and appears to indicate the severity of the disease. Other ancillary but common findings are left atrial dilatation, a small pericardial effusion, thickening of cardiac valves, papillary muscles, and interatrial septum. Finally, there is a peculiar texture of myocardial walls, with highly refractile areas that are typical, although not specific, of myocardial amyloidosis and can also be quantitatively described by digital image analysis techniques. The echocardiographic appearance of amyloidosis can closely mimic several other diseases. Asymmetric hypertrophy of the septum due to amyloid deposition may occur, simulating hypertrophic cardiomyopathy. The granular sparkling of myocardial walls is also found in myocarditis with severe fibrosis, and it is quite common in hypertrophic cardiomyopathy, as well as in other infiltrative diseases of the myocardium. It is not uncommon that the echocardiographic examination represents a turning point in the work-up of the patient, briskly orienting the clinician towards the correct diagnostic pathway. However, the likelihood of the cardiologist-echocardiographer to successfully and prespectively identify myocardial amyloidosis is substantially higher if all the clinical and electrocardiographic information is reviewed at the time of the echocardiographic examination
Quantitative texture analysis in two-dimensional echocardiography: Application to the diagnosis of myocardial amyloidosis
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