Uma fonte chaveada de 50kW com correção de fator de potência para alimentação de uma tocha de plasma Indutiva utilizando técnicas de controle digital

This work deals with the development of an experimental study on a power supply of high frequency that provides the toch plasmica to be implemented in PLASPETRO project, which consists of two static converters developed by using Insulated Gate Bipolar Transistor (IGBT). The drivers used to control these keys are triggered by Digital Signal Processor (DSP) through optical fibers to reduce problems with electromagnetic interference (EMI). The first stage consists of a pre-regulator in the form of an AC to DC converter with three-phase boost power factor correction which is the main theme of this work, while the second is the source of high frequency itself. A series-resonant inverter consists of four (4) cell inverters operating in a frequency around 115 kHz each one in soft switching mode, alternating itself to supply the load (plasma torch) an alternating current with a frequency of 450 kHz. The first stage has the function of providing the series-resonant inverter a DC voltage, with the value controlled from the power supply provided by the electrical system of the utility, and correct the power factor of the system as a whole. This level of DC bus voltage at the output of the first stage will be used to control the power transferred by the inverter to the load, and it may vary from 550 VDC to a maximum of 800 VDC. To control the voltage level of DC bus driver used a proportional integral (PI) controller and to achieve the unity power factor it was used two other proportional integral currents controllers. Computational simulations were performed to assist in sizing and forecasting performance. All the control and communications needed to stage supervisory were implemented on a DSP

Estado nutricional antropométrico, composição corporal e pressão arterial em adolescentes

Os objetivos deste trabalho foram: (1) estimar as prevalências de excesso de peso e de gordura corporal, obesidade central e pressão arterial elevada (PAE) em adolescentes beneficiários do Programa Nacional de Alimentação Escolar (PNAE) da rede municipal de ensino de Natal-RN; (2) verificar a associação entre variáveis antropométricas e de composição corporal com a pressão arterial, a maturação sexual e a história familiar positiva de fatores de risco para doença cardiovascular (FRDCV); (3) comparar dois padrões de referência para classificação do excesso de peso em adolescentes; e (4) propor equações preditivas de massa gorda (MG) e massa livre de gordura (MLG) baseadas nos perímetros corporais. Trata-se de um estudo transversal, com 526 adolescentes beneficiários do PNAE, em Natal, Brasil. O tamanho da população de estudo foi definido por amostragem aleatória, em dois estágios, e ponderada segundo número de alunos de cada escola. No primeiro estudo, o excesso de peso foi determinado por Índice de Massa Corporal (IMC), a gordura corporal estimada por dobras cutâneas e a obesidade central por perímetro abdominal. A pressão arterial elevada foi classificada conforme a American Academy of Pediatrics. As prevalências foram apresentadas em valores relativos e efeito do desenho. Realizou-se uma análise fatorial para sintetizar o conjunto de variáveis antropométricas visando identificar fatores comuns. Extraíram-se dois fatores: (1) padrão excesso de adiposidade e (2) padrão adiposidade central elevada. Para avaliar a associação entre os padrões de adiposidade corporal com pressão arterial elevada, faixa etária, maturação sexual e história familiar de FRDCV utilizou-se a Razão de Chances e respectivo intervalo de confiança de 95% e regressão logística. No segundo estudo, calculou-se a sensibilidade e a especificidade do excesso de peso classificado segundo o IOTF e a World Health Organization WHO em relação ao excesso de adiposidade corporal; e a estatística Kappa para medir a concordância entre os dois padrões de referência. No terceiro estudo, foram elaborados modelos preditivos de MG e MLG com base em nove perímetros corporais, utilizando a bioimpedância Byodinamics 450 como padrão de referência. Para tanto foram selecionados 218 adolescentes eutróficos, segundo o IMC a partir do estudo transversal. As equações foram estimadas por regressão linear múltipla, considerando a idade e os perímetros corporais. Os resultados apontaram que 14,1% dos meninos e 15,7% das meninas tinham excesso de peso; 15,3% dos meninos e 11,6% das meninas tinham excesso de gordura corporal e dentre os meninos 14,3% tinham pressão arterial elevada e as meninas, 21,4%. Todos os efeitos do desenho foram inferiores a 2,5%. Nos meninos, o padrão excesso de adiposidade foi associado à história familiar positiva de FRDCV (ORajust=2,60; 1,09-6,22), maturação sexual (ORajust=2,92; 1,04-8,22) e PAE (ORajust=3,66; 1,34-9,94). Os meninos com 12 anos e mais apresentaram 6,1 vezes mais chance de apresentar padrão adiposidade central elevada do que os adolescentes com 10 a 11 anos (IC95% 2,32-16,04), assim como os púberes apresentaram 3,2 vezes este mesmo padrão em relação aos pré-púberes (IC95%1,14-8,85). A partir da comparação entre os dois padrões de referencia de classificação do excesso de peso por meio do IMC, observou-se que a sensibilidade foi de 79,3% para o critério IOTF e de 88,9% para WHO e a especificidade foi de 94,7% e 89,9%, respectivamente. O nível de concordância foi maior para o critério IOTF (Kappa=0,70 x Kappa=0,64). Em relação à construção das equações preditivas de gordura corporal, do total de 106 meninos e 112 meninas, foram desenvolvidas duas equações para estimar MG e duas para MLG, considerando o sexo. No sexo masculino, a equação para estimar a MG incluiu as variáveis idade, punho, quadril e perímetro abdominal (R2=0,552; AIC=416,04) e MLG, idade, punho e antebraço (R2=0,869; AIC=578,24). Enquanto que no feminino, MG foi estimada pelas variáveis punho, perímetro do abdômen, do quadril, da coxa proximal e da panturrilha (R2=0,838; AIC=415,36); e a MLG por idade, punho, perímetro do abdômen, do quadril e da panturrilha (R2=0,878; AIC=512,48). Conclui-se que os adolescentes tinham elevada prevalência de excesso de adiposidade corporal e de pressão arterial elevada. Tanto o padrão excesso de adiposidade quanto adiposidade central elevada constituem-se em padrões de risco. O padrão excesso de adiposidade foi associado à pressão arterial, história familiar positiva de FRDCV e maturação sexual em meninos. O critério IOTF mostrou-se menos sensível, mais específico, com maior nível de concordância e maior probabilidade de identificar corretamente o excesso de gordura corporal nos adolescentes avaliados. Quatro equações foram desenvolvidas para a estimativa da MG e MLG em adolescentes. As equações desenvolvidas para estimar a MG no sexo feminino e MLG para ambos os sexos apresentaram valores elevados de coeficiente de determinação ajustados e, portanto, são as preferenciais. Este estudo foi realizado com a participação de equipe multidisciplinar composta por professores da área de Nutrição, Endocrinologia Pediátrica, Estatística, Educação Física, discentes do Curso de Graduação em Nutrição e residentes em Pediatria

Risco de doença cardiovascular em mulheres com história de distúrbio hipertensivo da gravidez

OBJECTIVE: Preeclampsia is a disease that can lead to a high maternal and infant morbidity. Worldwide, the incidence of this disease is highly variable and there is no data on this disorder in the Brazilian population. This study aimed at determining incidence and risk factors in the hypertensive disorders during pregnancy in a neighborhood of Natal, in addition to observing the evolution of these disorders one year and five years after delivery. METHODS: Prospective cohort study to assess the outcome of pregnancies of 242 women who became pregnant between 2004-2007 in the neighborhood of Bom Pastor in the city of Natal, state of RN, Brazil. Five years after delivery, there was an active search of thirty-nine (39) women who became pregnant and had a hypertensive disorder during pregnancy and/or pré-eclâmpsia, out of the total of 242 participants in the initial study. We administered a structured questionnaire to obtain basic information about the current clinical situation of patients and occurrences of subsequent pregnancy and presence of hypertensive disorders during pregnancy. We also searched for information on the use of hypotensive drugs and contraceptives. The following characteristics were checked and recorded: a) current weight, b) blood pressure c) body mass index - BMI, and we collected biological samples (blood and urine) for measurement of biochemical parameters and evaluation of microalbuminúria. Finally, we monitored the ambulatory blood pressure (ABP), which uses the method of automatic measurement of heart rate, systolic and diastolic blood pressure and an average of the two for the period of 24 hours. RESULTS: Out of 218 women who completed the study, the incidence of hypertensive disorders was of 16.9% (37 out of 218), while the incidence of preeclampsia was 13.8% (30 of 218). Women with preeclampsia had a BMI (body mass index) averaged of 25.3 (± 4.8) while this ratio in normotensive women was of 23.5 (± 3.7), p = 0.02. The risk of preeclampsia rises with age (OR 1084 p = 0.0034) and with a family history of hypertension (OR 2.6 p = 0.01). The follow-up one year after delivery revealed that 50% of women with hypertensive disorders in pregnancy remained hypertensive. High BMI was also observed after 5 years of delivery. CONCLUSIONS: an elevated BMI, age above 35 years and excessive weight gain during pregnancy were associated with hypertension in the long term in patients with prior preeclampsia. History of preeclampsia increases the risk of chronic hypertension

Ensino de matemática, história da matemática e artefatos: Possibilidade de interligar saberes em cursos de formação de professores da Educação Infantil e anos iniciais do Ensino Fundamental.

This work is located at the shield of research that defends the use of Mathematics History, based on the utilization of historical artifacts at teaching activities, at Mathematics classrooms, and at graduation courses for teachers of Elementary School and of the first grades of High School. The general objective is to examine the possibility of the use of historical artifacts, at teaching activities, at graduation courses for teachers of Elementary School and of the first grades of High School. Artifact, at this work, is comprehended as objects, documents, monuments, images and other kinds of materials that make sense to the Human actions at the past and that represent what have been said and done at the Human history. At the construction of the theoretical-methodological way of the research we have based ourselves upon the ideas of the authors that are engaged at the teachers formation; at researchers adherents to the use of Mathematics History (MH) as a methodological resource, and at studies accomplished that elucidate the role of the artifacts at the history and as a mediatory element of learning. We defend the thesis that the utilization of historical artifacts at teaching activities enables the increasing of the knowledge, the development of competencies and essential abilities to the teacher acting, as well as interact at different areas of the knowledge, that provides a conception of formation where the teacher improves his learning, learning-doing and learning-being. We have adopted a qualitative research approach with a theoretical and pratic study disposition about the elements that contribute to the teachers works at the classroom, emphasizing the role of the Mathematics history at the teacher s formation and as a pedagogical resource at the mathematics classroom; the knowledge, the competencies and abilities of the historical artifacts as an integrative link between the different areas of the knowledge. As result, we emphasize that the proposition of using the MH, through learning activities, at the course of teacher graduation is relevant, because it allows the investigation of ideas that originate the knowledge generated at every social context, considering the contribution of the social and cultural, political and economical aspects at this construction, making easy the dialog among the areas and inside of each one The historical artifact represents a research source that can be deciphered, comprehended, questioned, extracting from it information about knowledge of the past, trace and vestiges of the culture when it was created, consisting of a testimony of a period. These aspects grant to it consideration to be explored as a mediatory element of the learning. The artifacts incorporated at teaching activities of the graduation courses for teachers promote changes on the view about the Mathematics teaching, in view of to privilege the active participation of the student at the construction of his knowledge, at the reflection about the action that has been accomplished, promoting stimulus so the teachers can create their own artifacts, and offer, either, traces linking the Mathematics with others knowledge areas.

Ensino de matemática pelo rádio (1950 1970): uma história falada e um documentário didático

This study aimed to describe and analyze aspects of the historical course of teaching Mathematics by Radio Experiences in Rio Grande do Norte, between the decades from 1950 to 1970 in order to organize a documentary (CD-ROM) containing information about Mathematics studied by Radio who have experienced it. In this, we use qualitative research. We seek support in the theoretical framework of cultural history and memory researchers as Certeau (1998), Chartier (1990), Le Goff (2008), Thompson (2002) and Peter Burke (2004). Moreover, we take the elements of oral history. We focus on the teaching of literacy and the primary of the Radio schools in two rural communities - Logradouro and Catolé - who are currently part of the city of Lagoa Salgada (RN) and, with respect to the Junior High School, we stopped in the Course of Madureza at Radio. We used as written sources, especially the documents found in the General Archives of the Archdiocese of Natal (RN) and the employees assigned by the participants of the survey. Our sources come from the oral testimonies of pupils and monitors Lagoa Salgada City, teachers, broadcasters and technicians of Rural Support Service (SAR) Natal (RN). In this study, we identify the geometry Cubação social practices of Lagoa Salgada students. Also identified in the research material, the Global Method with the pedagogy of Paulo Freire, that guided the production of lessons in literacy and primary courses. Content in Mathematics, we find traces of the trend-Empirical activist. In the course of Madureza, there was a tendency formal technique Fiorentini (1995). Finally, as a result of this study, organize and present a documentary (CD-ROM), along with the analysis of this study, containing the history of Mathematics teaching by Radio, from the speech of those who experienced Radio, emphasizing the methodology teaching developed in class, that serves as a reference material for students, professors and researchers.

Recorte dos produtos educacionais em história no ensino da matemática e em didática da matemática a partir das dissertações e teses defendidas no brasil entre 1990-2010

This work has the main purpose of conducting a survey of educational products present in dissertations and doctoral theses focused on the use of history in mathematics teaching and Didactics of mathematics with a French foundation produced in graduate programs in the strict sense of the Brazil between 1990 and 2010, the areas of Education, Mathematics Education, school of Natural Sciences and Mathematics and related areas, according to the research proposal of Mendes (2010). Our interest was to select the products that present concrete proposals for educational activities that can be used in the classroom of Basic Education and Training of Teachers of Mathematics. The research was implemented through a bibliographic study documents the Bank of dissertations and theses from CAPES, libraries and archives of some Postgraduate programs in the country who focus their studies on the subject object of this research, besides the Brazilian Digital Library Theses and Dissertations (BDBTD). From this survey we selected works that present educational products materialized in blocks of activities based on the use of teaching history of mathematics to the classroom as well as the sequence of activities based on the Teaching of Mathematics. In possession of material, produce a CD-ROM containing the selected activities, in order to help support the work of teachers regarding the use of these activities, as a supplementary material to textbooks in their math classes