3 research outputs found
Determination of the association of urine prostate specific antigen levels with anthropometric variables in children aged 5-14 years
Determination of the association of urine prostate specific antigen levels with anthropometric variables in children aged 5-14 years
PURPOSE: Calculation of PSA is possible in human fluids even if it presents in very low concentrations with the help of hypersensitive immunodiagnostic methods. The periurethral glands represent one of the potential sources of urine prostate specific antigen (uPSA) in both sexes but the purpose of studying PSA levels in children is still unclear in the literature. In this pilot study we studied uPSA in a small cohort of normal, pre and post pubertal children, in relation to standard anthropometric variables. MATERIALS AND METHODS: The study cohort consisted of 58 children 5-14 years old (42 boys/16 girls). Height, weight, body mass index (BMI) and the respective stature-for-age, weight-for-age and BMI-for-age percentiles of the sample were determined. uPSA levels were measured using a third generation immunodiagnostic method (DPC Immulite®) that has a lower limit of detection of 3 ng/L. When levels of PSA were above the upper limit of detection, uPSA levels were assessed using the ROCHE technique. RESULTS: uPSA levels tend to be higher in male than female children (p = 0.091, linear regression analysis). uPSA was measurable only in 3/16 girls (18.75%). Measurable uPSA was found in 18/42 boys (42.8%). The range of urine PSA in boys was 0-161000 ng/L (mean 10561.9 ± 31830.48 ng/L). Statistical analysis with linear regression showed correlation with height and age in boys. CONCLUSIONS: The use of hypersensitive assays allows calculation of uPSA in childhood. The values of this variable are measurable in both sexes and related with gender. In boys, uPSA was correlated with age and height but not with other variables tested. Further studies are required to clarify this field
SMT-Based Stability Verification of an Industrial Switched PI Control Systems
International audienceThe control of complex systems is typically designed describing the physical system with differential equations. The standard approach to their verification employs numerical analysis, which is suitable to prove stability properties, but is susceptible of numerical errors. On the other side, symbolic techniques give precise analysis results but typically do not scale to industrial size problems. In this paper, we consider the control design of an aircraft engine. The engine model is represented by a linear state space model of 18 internal state variables, 4 outputs, and 3 inputs. The control switches between two PI controllers, one for thrust control and another for low-pressure compressor spool speed control, based on the engine state and pilot commands. After reformulating the PI controllers in terms of differential equations, we obtain a hybrid system with 21 state variables and two modes, for which we want to prove with symbolic techniques the robustness of the stable states to perturbation. We achieved the verification with standard methods to synthesize quadratic Lyapunov functions and SMT techniques to synthesize neighborhoods of the stable states for which we have symbolic proof of stability