Control of Structures with Cubic and Quadratic Non-Linearities with Time Delay Consideration

This paper studies the effect of time delay on the active non-linear control of dynamically loaded flexible structures. The behavior of non-linear systems under state feedback control, considering a fixed time delay for the control force, is investigated. A control method based on non-linear optimal control, using a tensorial formulation and state feedback control is used. The state equations and the control forces are expressed in polynomial form and a performance index, quadratic in both state vector and control forces, is used. General polynomial representations of the non-linear control law are obtained and implemented for control algorithms up to the fifth order. This methodology is applied to systems with quadratic and cubic non-linearities. Strongly non-linear systems are tested and the effectiveness of the control system including a delay for the application of control forces is discussed. Numerical results indicate that the adopted control algorithm can be efficient for non-linear systems, chiefly in the presence of strong non-linearities but increasing time delay reduces the efficiency of the control system. Numerical results emphasize the importance of considering time delay in the project of active structural control systems.

Training graduate students to be teachers

Pedagogic education of graduate students, when and where it exists, is restricted to theoretical courses or to the participation of the students as teachers' assistants. This model is essentially reproductive and offers few opportunities for any significant curriculum innovation. To open an opportunity for novelty we have introduced a new approach in "Biochemistry Teaching", a course included in the Biochemistry Graduate Program of the Biochemistry Department (Universidade Estadual de Campinas and Universidade de São Paulo). The content of the course consists of a) choosing the theme, b) selecting and organizing the topics, c) preparing written material, d) establishing the methodological strategies, e) planning the evaluation tools and, finally, f) as teachers, conducting the course as an optional summer course for undergraduate students. During the first semester the graduate students establish general and specific educational objectives, select and organize contents, decide on the instructional strategies and plan evaluation tools. The contents are explored using a wide range of strategies, which include computer-aided instruction, laboratory classes, small group teaching, a few lectures and round table discussions. The graduate students also organize printed class notes to be used by the undergraduate students. Finally, as a group, they teach the summer course. In the three versions already developed, the themes chosen were Biochemistry of Exercise (UNICAMP), Biochemistry of Nutrition (UNICAMP) and Molecular Biology of Plants (USP). In all cases the number of registrations greatly exceeded the number of places and a selection had to be made. The evaluation of the experience by both graduate and undergraduate students was very positive. Graduate students considered this experience to be unique and recommended it to their schoolmates; the undergraduate students benefited from a more flexible curriculum (more options) and gave very high scores to both the courses and the teachers.

Prevalence of syphilis in pregnancy and prenatal syphilis testing in Brazil: Birth in Brazil study

OBJECTIVE Determine the coverage rate of syphilis testing during prenatal care and the prevalence of syphilis in pregnant women in Brazil. METHODS This is a national hospital-based cohort study conducted in Brazil with 23,894 postpartum women between 2011 and 2012. Data were obtained using interviews with postpartum women, hospital records, and prenatal care cards. All postpartum women with a reactive serological test result recorded in the prenatal care card or syphilis diagnosis during hospitalization for childbirth were considered cases of syphilis in pregnancy. The Chi-square test was used for determining the disease prevalence and testing coverage rate by region of residence, self-reported skin color, maternal age, and type of prenatal and child delivery care units. RESULTS Prenatal care covered 98.7% postpartum women. Syphilis testing coverage rate was 89.1% (one test) and 41.2% (two tests), and syphilis prevalence in pregnancy was 1.02% (95%CI 0.84;1.25). A lower prenatal coverage rate was observed among women in the North region, indigenous women, those with less education, and those who received prenatal care in public health care units. A lower testing coverage rate was observed among residents in the North, Northeast, and Midwest regions, among younger and non-white skin-color women, among those with lower education, and those who received prenatal care in public health care units. An increased prevalence of syphilis was observed among women with < 8 years of education (1.74%), who self-reported as black (1.8%) or mixed (1.2%), those who did not receive prenatal care (2.5%), and those attending public (1.37%) or mixed (0.93%) health care units. CONCLUSIONS The estimated prevalence of syphilis in pregnancy was similar to that reported in the last sentinel surveillance study conducted in 2006. There was an improvement in prenatal care and testing coverage rate, and the goals suggested by the World Health Organization were achieved in two regions. Regional and social inequalities in access to health care units, coupled with other gaps in health assistance, have led to the persistence of congenital syphilis as a major public health problem in Brazil.