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Biomedical subjects

R M Marques

Publications and source records attributed to R M Marques.

6 recordsLinked to original sources

Focal malignant liver lesions: diagnosis by dynamic incremental CT, early phase.

The purpose of our study was to evaluate the accuracy of dynamic incremental bolus-enhanced conventional CT (DICT) with intravenous contrast administration, early phase, in the diagnosis of malignancy of focal liver lesions. A total of 122 lesions were selected in 74 patients considering the following criteria: lesion diameter 10 mm or more, number of lesions less than six per study, except in multiple angiomatosis and the existence of a valid criteria of definitive diagnosis. Lesions were categorized into seven levels of diagnostic confidence of malignancy compared with the definitive diagnosis for acquisition of a receiver-operator-characteristic (ROC) curve analysis and to determine the sensitivity and specificity of the technique. Forty-six and 70 lesions were correctly diagnosed as malignant and benign, respectively; there were 2 false-positive and 4 false-negative diagnoses of malignancy and the sensitivity and specificity obtained were 92 and 97%. The DICT early phase was confirmed as a highly accurate method in the characterization and diagnosis of malignancy of focal liver lesions, requiring an optimal technical performance and judicious analysis of existing semiological data.

Adolescent↗

The modified - Spillman model for asymptotic regression.

In order to describe teen-agers height growth a new asymptotic model called Spillman modified model is presented. The model introduces a non-linear enlargement of independent variable in the Spillman model and fits excellently to the observed data in comparison with the Spillman, logistic, Gompertz, and log-inverse models.

Adolescent↗

[Least squares fitting of a beta distribution to age-specific fertility rates].

"The paper shows at first that using the method of moments to estimate the parameters of a Beta function to fit age specific fertility rates is inadequate. A solution by means of the least squares method is proposed, under the constraint that the implied Total Fertility Rate should equal the observed value." This "iterative solution by means of the Newton-Raphson method turns out to be extremely efficient, converging in only a few steps. In addition, some characteristics of the Beta distribution related to the problem are obtained. The results, applied to 1980 data from the State of Sao Paulo [Brazil], clearly show a better global fit, especially in the area around the peak of the fertility curve." (summary in ENG)

Americas↗