Objective: To investigate the knowledge of adolescents related to sexually transmitted infections (STIs), AIDS, and pregnancy, and understand the role of school in sex education. Method: A qualitative descriptive study, developed through a semi-structured interview and a form for participant characterization, with 22 high school students from a public school aged 16 to 19 years. Data were submitted to content analysis. Results: After analysis, four thematic categories were developed: sexuality and sex education; understanding of risk behaviors; knowledge of STI/AIDS; and knowledge of and practices for prevention. Final considerations: This study showed the need for preventive educational actions for adolescents, because the lack of information contributes to their vulnerability. The adolescents recognize the importance of sex education; therefore it is important to implement strategies to promote and protect health in the school environment to encourage and strengthen self-care in health. Descriptores: Adolescent; Pregnancy in adolescence; Sexually transmitted diseases; Sex education; Knowledge. RESUMO Objetivo: investigar o conhecimento de adolescentes relacionado às Infecções Sexualmente Transmissíveis (IST), AIDS e gravidez, além de conhecer a compreensão sobre o papel da escola na educação sexual. Método: estudo qualitativo, descritivo, desenvolvido por meio de entrevista semiestruturada e formulário para caracterização dos participantes, com 22 adolescentes entre 16 e 19 anos de idade, estudantes do Ensino Médio em uma escola pública. Os dados foram submetidos à análise de conteúdo. Resultados: da análise emergiram quatro categorias temáticas: Sexualidade e educação sexual; Compreensão de comportamentos de risco; Conhecimento de IST/AIDS; Conhecimento e práticas de prevenção. Considerações fi nais: revelou-se a necessidade de ações educativas de prevenção para os adolescentes, pois a falta de informações contribui para a sua vulnerabilidade. Os adolescentes reconhecem a importância da educação sexual; consequentemente, é importante a implementação de estratégias de promoção e de proteção à saúde no ambiente escolar para contribuir e fortalecer o autocuidado na saúde. Descritores: Adolescente; Gravidez na Adolescência; Doenças Sexualmente Transmissíveis; Educação Sexual; Conhecimento. RESUMEN Objetivo: Investigar el conocimiento de adolescentes acerca de Enfermedades de Transmisión Sexual (ETS), SIDA y embarazo, además de conocer la comprensión del papel de la escuela en la educación sexual. Método: estudio cualitativo, descriptivo, desarrollado mediante entrevista semiestructurada y formulario de caracterización de participantes, con Knowledge of adolescents regarding sexually transmitted infections and pregnancy Almeida RAAS, et al.

No abstract

Summary This paper presents the experimental investigation of an electromagnetic suppressor to minimize the circulation of zero‐sequence currents in three‐phase four‐wire distribution systems. The proposed zero‐sequence current electromagnetic suppressor (ZSS) integrates two distinct electromagnetic devices, namely a zero‐sequence filter (ZSF) and a zero‐sequence blocker (ZSB), connected in parallel and in series between the source and the load, respectively. In this paper are presented the theoretical modeling and analysis of each device, the mathematical concepts of harmonic compensation, and the procedures for the design and determination of the constructive details. The experimental results of the combined operation of the devices that integrate the ZSS demonstrate the feasibility of the proposed arrangement, by minimizing the flow of the zero‐sequence harmonic currents in the source side, enabling a significant reduction of the current in the neutral conductor, and also by improving the system power factor.

No abstract

Multipulse rectifier topologies based on autoconnections, or differential connections, are more and more applied as interface stages between the mains and power converters. These topologies mitigate many low-order current harmonics in the utility, reducing the THD (total harmonic distortion) and increasing the power factor. This paper presents a mathematical model based on phasor diagrams, that results in a single expression able to unify all differential topologies connections (Delta and Wye), for both step-up or step-down autotransformers, for 12 and 18-pulse AC-DC converters. The proposed family of converters can be designed for any relationship between the input voltage and the load voltage. An immediate application would be the "retrofit", i.e. to replace a conventional rectifier with poor quality of the processed energy by the 12 or 18 pulses rectifier with Wye or Delta-differential connection. The design procedure, simple and fast, is developed and tested for a prototype rating 6 kW and 250 V on the DC load I.