Quadcopter is a type of Unmanned Aerial Vehicle which is lifted and propelled by four rotors. The vehicle has a complex non-linear dynamic which makes the tuning of the roll and pitch controllers difficult. Usually the control design is based on a mathematical model which is strongly related to physical components of vehicle: mass, moment of inertia and aerodynamic. When a tool is attached to the vehicle, a new model must be computed to redesign the controllers. In this article we will adjust the controllers of a real experimental quadcopter using the Cascade Iterative Feedback Tuning method. The method is data-driven, so it does not uses a model for the vehicle; all it uses is input-output data collect from the closed-loop system. The method minimizes the \{H2\} error between the desired response and the actual response of the vehicle angle using the Newton-Raphson algorithm. The method achieves the desired performance without the need of the vehicle model, with low cost and low complexity.

PURPOSE: To determine whether family income, age and educational level of the mother of the family are associated with self-reported use of dental floss over a 13-year period in a city in southern Brazil. MATERIALS AND METHODS: A comparison of two household surveys was carried out where mothers of the family were interviewed using a structured questionnaire in order to obtain demographic, behavioural and socioeconomic information. In total, 852 and 984 households were included in 1996 and 2009, respectively. Self-reported use of dental floss was assessed dichotomously (yes/no). Poisson regression models were fitted to study the association between sociodemographic variables with the use of dental floss. Proportion ratios (PR) and 95% confidence intervals (95% CI) were reported. RESULTS: The proportion of dental floss use increased from 48% to 59% over 13 years. The probability of dental floss use increased 1.23 times from 1996 to 2009 (PR = 1.23; 95% CI 1.13-1.34). Households with mothers >/=50 years old presented a 28% lower probability of using dental floss than households with mothers

O presente artigo pretende inserir o teólogo franciscano Geraldo Odon (ca. 1290-1349) no debate historiográfico medieval acerca das diferentes solções oferecidas ao célebre paradoxo do mentiroso. Na primeira parte a autora apresenta rapidamente e de forma esquemática os principais tipos de solução ao sofisma para em seguida analisar o texto de Odon, respondendo à questão da sua originalidade.