Motivated by recent work on integrable flows of curves and 1+1 dimensional sigma models, several O(N)-invariant classes of hyperbolic equations Utx = f(U,Ut, Ux) for an N -component vector U(t, x) are considered. In each class we find all scalinghomogeneous equations admitting a higher symmetry of least possible scaling weight. Sigma model interpretations of these equations are presented.

BACKGROUND The test characteristics of head circumference (HC) measurement percentile criteria for the identification of previously undetected pathology associated with head enlargement in primary care are unknown. METHODS Electronic patient records were reviewed to identify children age 3 days to 3 years with new diagnoses of intracranial expansive conditions (IEC) and metabolic and genetic ...

BACKGROUND Newborns of certain immigrant mothers are smaller at birth than those of domestically born mothers. Contemporary, population-derived percentile curves for these newborns are lacking, as are estimates of their risk of being misclassified as too small or too large using conventional rather than tailored birth weight curves. METHODS We completed a population-based study of 766 688 sin...

Background: Application of growth indicators taken from other countries can cause misdiagnosis of underweight and stunting. In this study we compared the trend of anthropometric growth indicators between the elementary school students of Yazd with the international standards. Methods: The study population of this retrospective cohort study consisted of 591 primary school children in Yazd (285 g...

OBJECTIVE To describe the percentile values for body mass index (BMI), waist circumference (WC) and waist-to-height (WHtR) of children from Colombo, Brazil, and compare them with data of children from other countries. METHODS This was a cross-sectional study with a random sample of 2,035 children aged 6-11 years. Age-and sex-specific smoothed percentiles curves for BMI, WC and WHtR were creat...

OBJECTIVE To asses the values of echocardiographic measurements in normal children without cardiopathy and to build percentile curves, relating them to the body surface (BS, m(2)). METHODS We analyzed M-mode echocardiographic measurements for children between one and 144 months of age. We assessed right ventricular diastolic diameter (RVDd, mm) and left ventricular diastolic diameter (LVDd, m...