1,721,126 research outputs found
Effect of growth on variability of left ventricular mass: assessment of allometric signals in adults and children and of their capacity to predict cardiovascular risk.
No full textEffect of growth on variability of left ventricular mass: assessment of allometric signals in adults and children and of their capacity to predict cardiovascular risk.
No full textLeft ventricular mass and body size in normotensive children and adults: assessment of allometric relations and impact of overweight.
No full textThis study was designed to determine the most appropriate method to normalize left ventricular mass for body size.
BACKGROUND:
Left ventricular mass has been normalized for body weight, surface area or height in experimental and clinical studies, but it is uncertain which of these approaches is most appropriate.
METHODS:
Three normotensive population samples--in New York City (127 adults), Naples, Italy (114 adults) and Cincinnati, Ohio (444 infants to young adults)--were studied by echocardiography. Relations of left ventricular mass to body size were similar in all normal weight groups, as assessed by linear and nonlinear regression analysis, and results were pooled (n = 611).
RESULTS:
Left ventricular mass was related to body weight to the first power (r = 0.88), to body surface area to the 1.5 power (r = 0.88) and to height to the 2.7 power (r = 0.84), consistent with expected allometric (growth) relations between variables with linear (height), second-power (body surface area) and volumetric (left ventricular mass and body weight) dimensions. Strong residual relations of left ventricular mass/body surface area to body surface area (r = 0.54) and of ventricular mass/height to height (r = 0.72) were markedly reduced by normalization of ventricular mass for height2.7 and body surface area1.5. The variability among subjects of ventricular mass was also reduced (p < 0.01 to p < 0.002) by normalization for body weight, body surface area, body surface area1.5 or height2.7 but not for height. In 20% of adults who were overweight, ventricular mass was 14% higher (p < 0.001) than ideal mass predicted from observed height and ideal weight; this increase was identified as 14% by left ventricular mass/height2.7 and 9% by ventricular mass/height, whereas indexation for body surface area, body surface area1.5 and body weight erroneously identified left ventricular mass as reduced in overweight adults.
CONCLUSIONS:
Normalizations of left ventricular mass for height or body surface area introduce artifactual relations of indexed ventricular mass to body size and errors in estimating the impact of overweight. These problems are avoided and variability among normal subjects is reduced by using left ventricular mass/height2.7. Simple nomograms of the normal relation between height and left ventricular mass allow detection of ventricular hypertrophy in children and adults
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
Relation of left ventricular chamber and midwall function to age in normal children, adolescent and adults.
No full textVariations 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
Relation of left ventricular chamber and midwall function to age in normal children, adolescent and adults.
No full textAppropriate 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
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
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