Resumen: La aptitud física es uno de los marcadores de salud importantes como predictor de morbilidad y mortalidad de enfermedades cardiovasculares. Objetivos: Evaluar la relación entre masa grasa con indicadores antropométricos y comparar el desempeño de la aptitud física entre niños y adolescentes categorizados con adecuado y exceso de masa grasa. Sujetos y Método: estudio transversal descrip tivo en 863 escolares entre 6 a 17,9 años. Se midió el peso, estatura, circunferencia de cintura. Se evaluó la aptitud física (velocidad, agilidad y salto horizontal). Se calculó la masa grasa por ecuación antropométrica, se calculó el índice de masa corporal, índice ponderal, e índice cintura estatura. Se agruparon los datos por edad en 6 grupos. Resultados: Los niños de ambos sexos categorizados con adecuados niveles de masa grasa presentaron valores inferiores de índice de masa corporal, índice ponderal e índice cintura estatura en relación a los niños con elevados niveles de masa grasa. En la aptitud física, los niños con masa grasa adecuada fueron mejores que sus contrapartes con masa grasa elevada. En las niñas con masa grasa adecuada, se observó mejores resultados en el salto horizontal y agilidad durante la adolescencia. No hubo diferencias en la prueba de velocidad. Conclusión: La masa grasa puede ser considerada como una herramienta valiosa para determinar el exceso de grasa corporal y categorizar a niños y adolescentes con adecuado y exceso de masa grasa. Además, presentar niveles aceptables de masa grasa puede contribuir a una mejor forma física en los niños en el salto horizontal, agilidad y velocidad y en las niñas únicamente en el salto horizontal y agilidad.

Abstract: Physical fitness is one of the important health markers as a predictor of cardiovascular disease morbidity and mortality. Objectives: To evaluate the relationship between fat mass with anthropometric indicators and, secondly, to compare the performance of physical fitness among children and adolescents categorized with adequate and excess fat mass. Subjects and Method: A descriptive cross-sectional study was conducted with 863 schoolchildren aged 6 to 17.9 years. Weight, height, and waist circumference were measured. physical fitness [speed (20m), agility (10x5m), and horizontal jump] was evaluated. Fat mass was calculated by anthropometric equation, body mass index, ponderal index, and waist to height ratio. Data were grouped into 6 age groups. Results: Children of both sexes categorized as having adequate levels of fat mass had lower values of body mass index, ponderal index, and waist to height ratio than children with high levels of fat mass. In physical fitness, children with adequate fat mass were better than the ones with elevated fat mass. In girls with adequate fat mass, better results were observed in horizontal jump and agility during adolescence. There were no differences in the speed test. Conclusion: Fat mass can be considered as a valuable tool for determining excess body fat and categorizing children and adolescents with adequate and excess fat mass. In addition, having acceptable levels of fat mass may contribute to better physical fitness in boys in horizontal jump, agility, and speed and, in girls, only in horizontal jump and agility.

Abstract Maximum oxygen consumption (VO2peak) is used in studies with adolescents to relate physical fitness to health status, and in the area of sports training to prescribe and evaluate training programs. The objective of the present study was to verify the VO2peak in adolescent soccer players, observing the type of training and body size. The sample consisted of 116 male adolescents, aged between 12 and 15 years old, divided into three groups, the Control Group (CG; n=45), the Educational Sports Group (ESG; n=45) and the Soccer Athletes Group ( SAG; n=26). Height and body mass were assessed. The Yo-Yo Intermittent Endurance Test was used to assess VO2peak. ANOVA (one way) was used to determine intergroup differences. VO2peak was allometrically adjusted by the exponent of -0.67. Initially, a better aerobic performance was observed in the ESG group compared to the GED. After allometric adjustment, the results pointed to a better performance of the SAG in relation to the GED and the ESG. We conclude that in order to evaluate VO2peak in adolescents it is necessary to take into account not only the type of training used (volume and intensity), but also their body size.

Resumo O consumo máximo de oxigênio (VO2pico) é utilizado em estudos com adolescentes para relacionar a aptidão física ao estado de saúde, e, na área do treinamento esportivo, para a prescrição e avaliação de programas de treinamento. O objetivo do presente estudo foi verificar o VO2pico em adolescentes praticantes de Futebol de campo observando o tipo de treinamento e o tamanho corporal. A amostra foi composta por 116 adolescentes masculinos, idade entre 12 e 15 anos, divididos em três grupos, o Grupo Controle (GC; n=45), o Grupo de Esporte Educacional (GEE; n=45) e o Grupo de Atletas de Futebol (GAF; n=26). Foram avaliadas a estatura e a massa corporal. O Yo-YoIntermittent Endurance Test foi utilizado para avaliar o VO2pico. Foi utilizada a ANOVA (one way), para determinar as diferenças intergrupos. O VO2pico foi ajustado alometricamente pelo expoente de -0,67. Inicialmente observou-se melhor desempenho aeróbio do grupo GEE em relação ao GED. Após o ajuste alométrico, os resultados apontaram para o melhor desempenho do GAF em relação ao GED e GEE. Conclui-se que para se avaliar o VO2pico em adolescentes é necessário levar-se em conta, não só o tipo de treinamento utilizado (volume e intensidade), mas também o seu tamanho corporal.

Abstract Introduction: studying the percentage of body fat (%BF) in children and adolescents is very relevant, since a high level of body fat in childhood and adolescence represents overweight and obesity. Objective: to identify the anthropometric indicators related to %BF and to validate regression equations to predict %BF in children and adolescents using dual-energy X-ray absorptiometry (DXA) as a reference method. Methods: a descriptive study (cross-sectional) was designed in 1126 schoolchildren (588 males and 538 females) from the Maule region (Chile). The age range ranged from 6.0 to 17.9 years. Weight, height, two skinfolds (tricipital and subscapular and waist circumference (WC) were evaluated. Body mass index (BMI), triponderal mass index (TMI), waist height index (WHtR) were calculated. Body fat percentage (%BF) was assessed by DXA scanning. Results: the relationships between Σ (Tricipital + Subscapular), TMI and WHtR with %BF (DXA) ranged from R2 = 52 % to 54 % in men, and from R2 = 41 % to 49 % in women. The equations generated for men were: %BF = 9.775 + [(0.415 * (Tr + SE)] + (35.084 * WHtR) - (0.828 * age), R2 = 70 %, and %BF = 20.720 + [(0.492 * (Tr + SE)] + (0.354 * TMI) - (0.923 * age), R2 = 68 %], and for women: %BF = 8.608 + [(0.291 * (Tr + SE)] + (38.893 * WHtR) - (0.176 * age), R2 = 60 %, and %BF = 16.087 + [(0.306 * (Tr + SE)] + (0.818 * TMI) - (0.300 * age), R2 = 59 %. Conclusion: this study showed that the sum of tricipital and subscapular skinfolds, IP and WHtR are adequate predictors of %BF. These indicators allowed the development of two regression equations acceptable in terms of precision and accuracy to predict %BF in children and adolescents of both sexes.

Resumen Introducción: estudiar el porcentaje de grasa corporal (%GC) en niños y adolescentes es muy relevante, puesto que un elevado nivel de grasa corporal en la infancia y la adolescencia representa sobrepeso y obesidad. Objetivo: identificar los indicadores antropométricos que se relacionan con el %GC y validar ecuaciones de regresión para predecir el %GC de niños y adolescentes a partir del uso de la absorciometría de rayos X de doble energía (DXA) como método de referencia. Métodos: se diseñó un estudio descriptivo (transversal) en 1126 escolares (588 hombres y 538 mujeres) de la región del Maule (Chile). El rango de edad oscila desde los 6,0 hasta los 17,9 años. Se evaluaron el peso, la estatura, dos pliegues cutáneos (tricipital y subescapular) y la circunferencia de la cintura (CC). Se calcularon el índice de masa corporal (IMC), el índice ponderal (IP) y el índice cintura-estatura (ICE). Se evaluó el porcentaje de grasa corporal (%GC) por medio del escaneo DXA. Resultados: las relaciones entre Σ (Tricipital + Subescapular), IP e ICE con el %GC (DXA) fueron de R2 = 52-54 % en hombres y R2 = 41-49 % en mujeres. Las ecuaciones generadas para los hombres fueron: %GC = 9,775 + [(0,415 * (Tr + SE)] + (35,084 * ICE) - (0,828 * edad), R2 = 70 %, y %GC = 20,720 + [(0,492 * (Tr + SE)] + (0,354 * IP) - (0,923 * edad), R2 = 68 %; y para mujeres: %GC = 8,608 + [(0,291 * (Tr + SE)] + (38,893 * ICE) - (0,176 * edad), R2 = 60 %, y %GC = 16,087 + [(0,306 * (Tr + SE)] + (0,818 * IP) - (0,300 * edad), R2 = 59 %. Conclusión: este estudio demostró que la sumatoria de los pliegues cutáneos tricipital y subescapular, el IP y el ICE son adecuados predictores del %GC. Estos indicadores permitieron desarrollar dos ecuaciones de regresión aceptables en términos de precisión y exactitud para predecir el %GC en niños y adolescentes de ambos sexos.

Resumo O objetivo deste estudo foi descrever a correlação entre dados de composição corporal obtidos através de DEXA, e pela estratégia de dobras cutâneas, com algumas de suas respectivas fórmulas, em velocistas. A amostra foi composta por 15 velocistas do sexo masculino (23,81 anos ± 3,11; 70,06 Kg ± 4,38; e 179,13 cm ± 5,16) todos corredores de alto desempenho das provas de velocidade e barreiras (100m, 200m, 400m, 110m com barreiras e 400m com barreiras). Os atletas foram submetidos ao procedimento de avaliação do DEXA e a coleta de dobras cutâneas (tricipital, bicipital, subescapular, supra ilíaca, abdominal, coxa medial e panturrilha) e os resultados calculados através de quatros distintas equações Slaughter, Faulkner, Lázari e Boileau. As respectivas correlações (0,60; 0,81; 0,23 e 0,48) de DEXA e as equações previstas pela estratégia de dobras cutâneas foram calculadas através da correlação de Pearson. Dentre as equações utilizadas, a de Faulkner foi a que apresentou maior valor de correlação quando comparada ao protocolo do DEXA, apesar de todas terem por objetivo estimar valores para o %G.

Abstract The aim of this study was to describe the correlation between body composition data obtained through DXA and through skinfolds strategy, with some of their respective formulas, in sprinters. The sample consisted of 15 male sprinters (23.81 years ± 3.11; 70.06 Kg ± 4.38; and 179.13 CM ± 5.16) all high performance runners of speed and barriers events (100m, 200m, 400m, 110m with barriers and 400m with barriers). The athletes were submitted to DXA evaluation procedure and to skinfolds collection (triceps, biceps, subscapular, supra iliac, abdominal, medial thigh and calf) and the results were calculated through four distinct equations: Slaughter, Faulkner, Lázari and Boileau. The respective DXA correlations (0.60; 0.81; 0.23 and 0.48) and the equations predicted by skinfold strategy were calculated using Pearson correlation. Among the equations used, Faulkner's was the one presenting highest correlation value when compared to DXA protocol, although all of them aimed to estimate values for BF%.

Abstract Introduction: the assessment of body composition is relevant and useful for designing interventions for healthy lifestyles and nutritional strategies. Objective: our goal was to verify the relationships between adiposity indicators with fat mass (FM), and to validate equations that allow predicting FM in young people with Down syndrome (SD). Methods: a cross-sectional study was carried out in 48 young people with DS (24 men and 24 women). Weight, height, waist circumference (WC), and hip circumference (HC) were evaluated. Body mass index (BMI), body adiposity index (BAI), waist-to-hip index (WHI), and waist-to-height index (WHtR) were calculated. FM was evaluated by dual energy X-ray absorptiometry (DXA). Results: age in men was 19.3 ± 3.0 years, and in women it was 18.9 ± 1.9 years; weight was 73.6 ± 14.3 kg in men and 75.8 ± 20.3 kg in women, and height in men was 168.9 ± 6.5 cm, and in women it was 156.3 ± 6.2 cm. In males the correlations between FM (DXA) with BMI, WC, HC, WHtR, BAI and WHtR ranged from r = 0.01 to r = 0.89, and in females from r = 0.10 to r = 0.97. The highest correlations were observed with BMI and WC in both sexes (males r = 0.78 to 0.92, and females r = 0.83 to 0.97). Regression equations were generated to estimate FM in males (R2 = 84 %) and in females (R2 = 96 %). Percentiles were calculated for MG per DXA and for each equation. Conclusions: there were significant positive correlations between BMI and WC with FM. These indicators were decisive for developing equations that estimate FM in young people with DS. The results suggest its potential use and application to evaluate, classify and monitor body fat levels in clinical and epidemiological contexts.

Resumen Introducción: la evaluación de la composición corporal es relevante y útil para diseñar intervenciones de estilos de vida saludables y estrategias nutricionales. Objetivos: verificar las relaciones existentes entre los indicadores de adiposidad y la masa grasa (MG), y validar ecuaciones que permitan predecir la MG en jóvenes con síndrome de Down (SD). Métodos: se efectuó un estudio transversal en 48 jóvenes con SD (24 hombres y 24 mujeres). Se evaluaron el peso, la estatura, la circunferencia de la cintura (CC) y la circunferencia de la cadera (CCa). Se calcularon el índice de masa corporal (IMC), el índice de adiposidad corporal (IAC), el índice cintura-cadera (ICC) y el índice cintura-estatura (ICE). Se evaluó la MG mediante absorciometría de rayos X de doble energía (DXA). Resultados: la edad de los hombres era de 19,3 ± 3,0 años y la de las mujeres de 18,9 ± 1,9 años; el peso era de 73,6 ± 14,3 kg en los hombres y de 75,8 ± 20,3 kg en las mujeres; finalmente, la estatura de los hombres era de 168,9 ± 6,5 cm y la de las mujeres de 156,3 ± 6,2 cm. En los hombres, las correlaciones entre la MG (DXA) y los parámetros IMC, CC, CCa, ICE, IAC e ICE oscilaron entre r = 0,01 y r = 0,89; en las mujeres, entre r = 0,10 y r = 0,97. Las correlaciones más altas se observaron con el IMC y la CC en ambos sexos (hombres, r = 0,78 a 0,92 y mujeres, r = 0,83 a 0,97). Se generaron ecuaciones de regresión para estimar la MG en los hombres (R2 = 84 %) y en las mujeres (R2 = 96 %). Se calcularon los percentiles de MG según la DXA y con cada ecuación. Conclusiones: hubo correlaciones positivas significativas del IMC y la CC con la MG. Estos indicadores fueron determinantes para desarrollar ecuaciones que estiman la MG de los jóvenes con SD. Los resultados sugieren su uso y aplicación para evaluar, clasificar y monitorizar los niveles de adiposidad corporal en contextos clínicos y epidemiológicos.

Abstract The Southeastern Brazilian Margin presents a NE-SW-striking structural framework, which is characteristic of the Neoproterozoic Ribeira Belt. Other important structural trends along the area are associated with E-W and NW-SE-striking structures, being most related to the Mesozoic-Cenozoic tectonic evolution. A succession of Cenozoic tectonic events has been described by many authors in the Southeastern Brazilian. Among those Cenozoic tectonic events, a Neogene to Quaternary E-W dextral strike-slip regime (EW-DT) shows a wide distribution, presenting some variations in the stress field orientation. This research investigates the influence of the preexisting structural framework on the variation of the paleostress field orientation associated with the EW-DT tectonic event in a selected area in the onshore continental margin of the Southeastern Brazil. The study was carried out in three main stages: lineament analysis, paleostress field analysis, and numerical mechanical modeling. The paleostress field related to the EW-DT tectonic event in the studied area presents: NNW-SSE-striking maximum horizontal stress, and counterclockwise rotation influenced by the structural framework. Regarding this, the regional variation of the paleostress field is influenced by a preferential reactivation of NE-SW-striking structures while sets of approximately E-W-striking structures are the main local control of counterclockwise rotation of the stress field.

RESUMO Objetivo: Identificar a prevalência do comportamento inativo de estudantes adolescentes da cidade de Porto Velho, RO, Brasil, e os fatores associados a ele. Métodos: Estudo de base escolar realizado com 2.694 adolescentes. A variável autorreferida à exposição ao desfecho foi a inatividade física. Verificam-se os fatores associados ao comportamento inativo pela regressão logística múltipla. As variáveis independentes foram inseridas no modelo em blocos hierarquizados. Resultados: A prevalência geral de comportamento inativo foi de 39,5%. O sexo feminino mostrou maior prevalência de comportamento inativo (46,2%) do que o masculino (31,4%). Adolescentes em escolas particulares e com relatos de percepção de saúde negativa apresentaram alta prevalência de comportamento inativo. Na verificação dos fatores associados, o sexo feminino mostrou magnitude de associação de 1,84 com o comportamento inativo. Estar institucionalizado em escola particular mostrou 2,54 vezes mais chance de ter comportamento inativo em comparação aos estudantes das escolas públicas. A locomoção para escola por ônibus e carro ou motocicleta revelou magnitudes de associação com o comportamento inativo de 1,29 e 1,63, respectivamente. Adolescentes que apontaram a percepção de saúde negativa tiveram 1,29 mais chance de ter comportamento inativo em relação ao relato de saúde positiva, enquanto ter excesso de gordura corporal mostrou magnitude de associação de 1,36 em adolescentes. Conclusões: A prevalência de comportamento inativo foi alta em estudantes adolescentes. Considerando que o comportamento inativo adotado durante a adolescência pode permanecer nos anos posteriores, sugere-se a promoção de ações para a modificação de comportamento visando à melhoria da saúde e qualidade de vida.

ABSTRACT Objective: To identify the prevalence of physical inactivity in adolescent students in the city of Porto Velho, RO, Northern Brazil, and its associated factors. Methods: School-based study, conducted with 2,694 adolescents. The self-reported variable for outcome was physical inactivity. Factors associated with inactive behavior were verified by multiple logistic regression. The independent variables were inserted into the model in hierarchical blocks. Results: The overall prevalence of inactive behavior was 39.5%. Females showed a higher prevalence of physical inactivity (46.2%) than males (31.4%). Adolescents in private schools and with reports of negative health perception had a high prevalence of physical inactivity. Regarding associated factors, the female sex showed a magnitude of association of 1.84 with physical inactivity. Being in a private school was associated with a 2.54 times greater chance of physical inactivity compared to public school students. Going to school by bus, car or motorcycle was associated with a 1.29 and 1.63 higher chance of physical inactivity respectively. Adolescents who reported having a negative health perception had 1.29 higher chance of physical inactivity, while having excess body fat showed magnitude of association of 1.36 in adolescents. Conclusions: There was a high prevalence of physical inactivity in the studied adolescents. Considering that the behavior of physical inactivity adopted during adolescence may continue in adulthood, the promotion of actions that can change this behavior may improve health in the future as well as quality of life.

Resumo O parasitismo intenso por tricodinídeos está frequentemente relacionado à doença grave em fazendas de peixes. Neste estudo, espécies de tricodinídeos das brânquias e da pele de tilápias do Nilo (Oreochromis niloticus) cultivadas na região centro-oeste do Brasil (estado de Goiás) foram caracterizadas morfologicamente. As lâminas secas foram preparadas a partir dos parasitas e impregnadas com nitrato de prata (2%). As características morfométricas foram determinadas e desenhos esquemáticos dos dentículos foram confeccionados com fotomicrografias produzidas a partir das lâminas. Sete espécies de ectoparasitos tricodinídeos (Protozoa: Ciliophora: Trichodinidae) foram encontradas parasitando as brânquias: quatro do gênero Trichodina Ehrenberg, 1838; um de Tripartiella Lom, 1959; um de Paratrichodina Lom, 1963; e um de Trichodinella Ṧrámek-Huṧek, 1953. Na superfície do corpo, três espécimes do gênero Trichodina foram identificados. Este estudo apresenta novos registros geográficos de tricodinídeos no Brasil, confirmando que Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana e Tripartiella orthodens estão amplamente distribuídas mundialmente. Adicionalmente, é apresentado o primeiro registro do gênero Trichodinella no Brasil.

Abstract Massive occurrence of trichodinids is frequently accompanied by serious disease in fish farms. In this study, trichodinid species from the gills and skin of Nile tilapia (Oreochromis niloticus) farmed in the central-western region of Brazil (state of Goiás) were morphologically characterized. Dried slides were prepared from the parasites and were impregnated with silver nitrate (2%). Morphometric characteristics were determined and schematic drawings of the denticles were made using photomicrographs produced from the slides. Seven species of trichodinid ectoparasites (Protozoa: Ciliophora: Trichodinidae) were found parasitizing the gills: four of the genus Trichodina Ehrenberg, 1838; one of Tripartiella Lom, 1959; one of Paratrichodina Lom, 1963; and one of Trichodinella Ṧrámek-Huṧek, 1953. On the body surface, three specimens of the genus Trichodina were identified. This study presents new geographical records of trichodinids in Brazil, thus confirming that Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana and Tripartiella orthodens are widely distributed worldwide. Additionally, the first record of the genus Trichodinella in Brazil is presented.

Este trabalho apresenta o desenvolvimento e resultados de testes de campo de um estabilizador de sistemas de potência (ESP) digital, destinado ao amortecimento de oscilações eletromecânicas em sistemas interligados. Os testes experimentais foram efetuados em uma das unidades hidrogeradoras, de 350 MVA, da UHE de Tucuruí. A lei de controle amortecedor do ESP digital foi embarcada em um sistema de hardware baseado em um controlador digital de sinais (DSPIC 30f5011). A estrutura da lei de controle é na forma canónica RST, de tempo discreto, sendo os parâmetros do controlador calculados através da técnica de deslocamento radial de pólos. Para fins de projeto, a dinâmica da planta, no ponto de operação considerado, foi representada por um modelo paramétrico, o qual foi estimado a partir de dados medidos em campo. Os resultados experimentais mostraram um excelente desempenho do ESP digital no amortecimento de um dos modos eletromecânicos observável na UHE de Tucuruí.

This paper presents the development and results of field tests of a digital power system stabilizer (PSS), designed for the damping of electromechanical oscillations in interconnected systems. Experimental tests were performed in a 350 MVA hydrogenerator unit, of the Tucurui Power Plant. The PSS damper control law was embedded in a digital hardware system based on a digital signal controller (DSPIC 30f5011). The structure of the control law is in discrete time RST canonical form, and the controller parameters were calculated using the pole shifting technique. For purposes of the controller design, the dynamics of the plant, in the considered operating point, was represented by a parametric model, which was estimated from data measured in the field. The experimental results showed an excellent performance of the damping of electromechanical modes observable UHE Tucurui by digital PSS.

Twisted-tape inserts are frequently used in heat exchangers as a passive and inexpensive heat transfer enhancement method. However, their use results not only heat transfer coefficient increments, but also pressure drop penalties. The present study analyses the literature on single and two-phase frictional pressure drop inside tubes with twisted-tape inserts focusing on the physical mechanism and the effects of the use of twisted-tape in comparison to plain tubes. Experimental data were gathered from the open literature and compared against the available correlations developed in order to predict two-phase frictional pressure drop in tubes containing twisted-tape inserts. It was found that none of the correlations was able to predict such a database accurately. A new correlation to estimate the friction factor for two-phase flows inside tubes with twisted-tape is also proposed. Contrarily to previous studies, the proposed correlation presents reasonable predictions under single and two-phase flow conditions and obeys the trends when the twisted-tape ratio tends to zero and infinite.