A subnutrição é uma condição muito prevalente em crianças gravemente doentes em todo o mundo, e está associada a maior morbimortalidade, incluindo maior risco de infecções devido à desordem imunológica transitória, cicatrização inadequada, função intestinal reduzida, maior dependência de ventilação mecânica e tempo de internação hospitalar. Estudos atuais têm proposto que uma intervenção nutricional precoce direcionada pela avaliação nutricional pode prevenir ou minimizar as complicações da subnutrição. O estresse promove uma resposta inflamatória aguda mediada por citocinas, que resulta em aumento do metabolismo basal e da excreção nitrogenada, levando a grande perda muscular e alterações da composição corpórea. Por essa razão, a inclusão da avaliação da composição corporal torna-se importante na avaliação desses pacientes gravemente doentes, uma vez que além do aspecto nutricional, a composição corporal parece ser capaz de predizer prognósticos clínicos. Existem várias técnicas para avaliar a composição corporal, como as medidas do braço e a bioimpedância elétrica (BIA). Dentre os parâmetros da BIA, o ângulo de fase (AF), que representa indiretamente a massa livre de gordura (MLG), é o mais clinicamente estabelecido, uma vez que tem mostrado grande capacidade de predizer desfechos em uma ampla variedade de situações clínicas. Dada a importância da análise da composição corporal como adjunta da avaliação nutricional e como possível indicadora de prognóstico de morbimortalidade em diversas situações clínicas, faz-se importante a realização de estudos que comprovem sua efetividade, especialmente em crianças gravemente doentes, onde os dados ainda são escassos. Objetivo: O objetivo deste estudo foi testar a associação do estado nutricional na admissão avaliado por indicadores de composição corporal - circunferência do braço (CB) e AF - com tempo de internação e mortalidade em até 30 dias em crianças e adolescentes gravemente doentes na unidade de terapia intensiva pediátrica (UTIP). Métodos: Foram coletados dados antropométricos e demográficos de crianças de 2 meses a 18 anos internadas na UTI do Instituto da Criança do Hospital das Clínicas da Universidade de São Paulo, no período de um ano. A avaliação nutricional antropométrica foi realizada nas primeiras 24 horas de admissão para caracterizar a população do estudo e incluiu peso, altura ou comprimento e índice de massa corporal (IMC), além da CB. A classificação antropométrica na admissão foi definida pelo escore z (Z) do IMC para a idade (IMC/I), utilizando os valores de referência da Organização Mundial da Saúde (OMS). Para a classificação da CB foram utilizados os percentis propostos por Frisancho. A BIA foi realizada para a obtenção do AF. Os pacientes admitidos foram avaliados quanto à gravidade por intermédio do escore \"Paediatric Index Mortality\" (PIM). Análise estatística descritiva foi utilizada para as variáveis nominais. Uma curva ROC (\"Receiver Operating Characteristic\") foi construída para analisar a associação do AF com mortalidade em até 30 dias na UTIP e encontrar o melhor cutoff associado a esta mortalidade. As probabilidades de sobrevivência foram estimadas pelo método de Kaplan-Meier e comparadas pelo teste de log-rank, e a taxa de falha foi determinada pelo modelo de regressão de Cox. A análise de tempo para o evento (curva de Kaplan-Meier) foi utilizada para avaliar a influência dos indicadores de composição corporal no tempo de internação na UTIP, seguida do teste de log-rank para verificar diferença significativa entre as curvas. Resultados: Foram avaliadas 247 crianças com mediana de idade de 4,8 anos e cuja principal causa de internação foi sepse. A mediana do tempo de internação na UTIP e do PIM foi de 4,0 e 2,7, respectivamente. Houve predomínio de pacientes eutróficos de acordo com o Z IMC/I (49,8%), e quase metade dos pacientes (49,8%) apresentou depleção da MLG segundo o percentil da CB (abaixo do percentil 5). O cutoff do AF associado à mortalidade em crianças gravemente doentes encontrado pela análise da curva ROC foi de 2,8° (AUC = 0,65; IC95%: 0,58-0,71), com sensibilidade de 37,1% e especificidade de 86%. As curvas mostraram maior sobrevivência em pacientes com AF > 2,8° quando comparados àqueles com AF <= 2,8° (53 vs 23 dias, respectivamente; p < 0,0001). A análise de Kaplan-Meier de tempo para o evento mostrou que as crianças que não morreram e apresentavam menores valores de AF tinham maior probabilidade de permanecerem internadas por mais tempo na UTI (HR: 1,84; p = 0,003). Menor sobrevivência também foi observada em pacientes que apresentavam percentis de CB inferior a 5 quando comparados aos com percentil de CB maior do que 5 (26 vs 28 dias; p < 0,03). Conclusões: Houve associação do AF e da CB com mortalidade e morbidade em crianças gravemente doentes, sugerindo que esses parâmetros podem ser úteis não apenas para o diagnóstico e monitoramento nutricional, mas também como um indicador adicional na estimativa do prognóstico. O cutoff de AF encontrado (2,8°) parece ser mais apropriado para avaliar a associação com mortalidade nessa população / Undernutrition is highly prevalent in critically ill children throughout the world and it is associated with increased morbidity and mortality, including a higher risk of infection due to transitory immunological disorder, inadequate wound-healing, reduced gut function, longer dependency on mechanical ventilation and longer hospital stays. Nutritional care studies have proposed that an early intervention targeting nutrition assessment can prevent or minimize the complications of undernutrition. Stress promotes an acute inflammatory response mediated by cytokines resulting in increased basal metabolism and nitrogen excretion leading to major muscle loss and changes in body composition. For this reason the inclusion of body composition assessment becomes important in the evaluation of these patients since in addition to the nutritional aspect, body composition seems to be able to predict clinical prognosis. There are several techniques to assess body composition, such as arm measurements and bioelectrical impedance analysis (BIA). Among the BIA parameters, the phase angle (PA), which indirectly represents fat free mass (FFM), is the most clinically established, since it has shown a strong ability to predict outcomes in a wide variety of clinical situations. Considering the importance of body composition analysis as an adjunctive nutritional assessment and as a possible morbidity and mortality predictor in many clinical situations, it is necessary to conduct studies that demonstrate this ability, especially in critically ill children, since data are still scarce. Objective: The aim of this study was to test the association of nutritional status on admission evaluated by body composition indicators - arm circumference (AC) and PA - with pediatric intensive care unit (PICU) length of stay (LOS) and 30-day mortality in critically ill children and adolescents. Methods: Anthropometric and demographic data from children aged 2 months to 18 years admitted to the PICU of Instituto da Criança, Hospital das Clínicas da Universidade de São Paulo during a one-year period were collected. Anthropometric nutritional assessment was performed within 24 hours of admission to characterize the study population. The assessment included weight, height or length, and body mass index (BMI), besides AC. Anthropometric classification on admission was defined by the BMI-for-age z-score using the reference values from the World Health Organization (WHO). CB was classified by percentiles proposed by Frisancho. BIA was performed to obtain PA. Severity was evaluated by scoring the Pediatric Index of Mortality (PIM). Descriptive statistics were reported for nominal variables. Receiver Operating Characteristic (ROC) curve was used to analyze the association of PA with 30-day mortality and to find the best cutoff. Survival probabilities were estimated by the Kaplan-Meier method, and they were compared using the log-rank test. The failure rate was estimated according to models of Cox regression. The Kaplan-Meier time-to-event analysis was used to assess the influence of the body composition indicators on the PICU LOS, followed by the log-rank test to verify any significant difference between the curves. Results: We evaluated 247 children with a median age of 4.8 years whose main cause of admission was sepsis. The median PICU LOS was 4 days and median PIM was 2.7. There was a predominance of eutrophic patients according to BMI-for-age z-scores (49.8%), and almost half of the patients (49.8%) presented FFM depletion according to the percentile AC (below the 5th percentile). PA cutoff associated with mortality in critically ill children found by the ROC curve analysis was 2.8° (AUC = 0.65; 95% CI: 0.58-0.71), with a sensitivity of 37.1% and a specificity of 86%. Survival curves showed higher survival in patients with PA > 2.8° compared to patients with PA <= 2.8° (53 vs 23 days respectively; p < 0.0001). Kaplan-Meier time-to-event analysis showed that children who did not die and had lower PA values were more likely to remain longer in the PICU (HR: 1.84; p = 0.003). Lower survival also observed in patients who presented AC values 5 (26 vs 28 days; p < 0.03). Conclusions: AC and PA were associated with mortality and morbidity in critically ill children, suggesting that these parameters may be useful not only for nutritional diagnosis and monitoring but also for an additional indicator in estimating prognosis. We found that a PA cutoff of 2.8° seems to be more appropriate to evaluate association with mortality for this population

Devido às dificuldades encontradas excessivas variabilidades de água no organismo do lactente, considera-se a análise vetorial de impedância bioelétrica (BIVA) um método propício para avaliação da composição corporal. Trata-se de um método que não faz nenhuma pressuposição sobre valores da composição corporal, podendo ser controlado por seus próprios valores, independente de equações ou modelos. Os objetivos deste estudo foram descrever valores de referência e criar curvas de BIVA para lactentes saudáveis de 30 a 90 dias de vida e descrever valores de normalidade de ângulo de fase em lactentes a termo, sadios e adequados para a idade gestacional de 30 a 90 dias de idade, além de comparar os dados de BIVA entre os sexos e entre os existentes na literatura para neonatos e lactentes jovens, com os obtidos neste estudo. Este estudo descritivo transversal avaliou 150 lactentes do Centro Médico Social Comunitário Vila Lobato de Ribeirão Preto - SP - Brasil. Foram coletados dos lactentes os dados antropométricos e a impedância bioelétrica (aparelho de monofrequência RJL System ® modelo Quantum II - 800 ?A e 50 KHz). Usando distribuição bivariável normal de resistência e reactância por comprimento (R/H e Xc/H) do lactente, respectivamente, foram calculados e assim confeccionados os gráficos RXc com os intervalos de tolerância de 95, 75, 50% do valor vetorial da impedância por meio do BIVA Software 2002. Foram avaliados 150 lactentes (48,6% do sexo feminino), nascidos a termo, adequados para idade gestacional e em aleitamento materno exclusivo. A idade média foi 56,4 (± 23,1) dias. O peso médio encontrado foi de 5038,5g (± 902,4), sendo maior no sexo masculino (p = 0,001). Quanto ao comprimento corporal, a média foi 56,0 cm (± 0,03), sendo maior no sexo masculino (p = 0,001). As médias de R (±DP) foram 521,2 (± 52,1); 519,4 (± 53,4) e 523,0 (± 51,1) ?, e para Xc foram 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectivamente para todos os lactentes, e separados por sexo (meninos e meninas), não havendo diferença entre os sexos (p = 0,6) e (p = 0,1). Em relação ao ângulo de fase, encontrou-se o valor de normalidade de 4,3° (± 0,7°) para todos os lactentes, 4,3° (± 0,6°) para os do sexo masculino e 4,4° (± 0,5°) para os do sexo feminino, não havendo diferença estatisticamente significativa (p = 0,3). Para a análise vetorial de lactentes de 30 a 90 dias de idade, devem ser utilizados os valores de referência específicos para esta faixa etária e sexo, pois estes se apresentaram diferentes dos descritos na literatura. Com o modelo de estudo BIVA torna-se possível a comparação direta do vetor medido na criança pequena ou com necessidade de cuidados especiais com os intervalos de tolerância de referência de lactentes saudáveis, permitindo uma avaliação qualitativa da composição corporal e sem erro de predição das fórmulas. Com os valores de ângulo de fase caracterizados no presente estudo para lactentes brasileiros saudáveis, de 30 a 90 dias de idade, dados de pacientes críticos podem ser comparados, sendo útil durante a internação e acompanhamento de pacientes graves. / Bioelectrical impedance vectorial analysis (BIVA) can be considered a favorable method for evaluation of the body composition, due to the difficulties in the early life and excessive variability of the amount of water in the organism of the infants. It is a method that doesn\'t make any presumption on values of the body composition, which can be controlled by their own values, with no need for validation based on gold standards, not depending on equations or models. The aims of the study are to establish reference values creating BIVA curves, and to establish reference values for phase angle in term infants, healthy and appropriate-forgestational age (AGA), from 30 to 90 days of life. This study still intend to compare the data of BIVA between genders, among newborns and young infants, presented in the literature, and the ones obtained in this study. This transversal cohort study assessed healthy infants of a Community Centre for Social Medicine Vila Lobato, located in Ribeirão Preto, São Paulo, Brazil. Data of infants, anthropometry and bioelectrical impedance were collected (singlefrequency - RJL System ® model Quantum II - 800 ?A and 50 KHz). Using bivariate normal distribution of R/H and Xc/H (resistance and reactance for infants length, respectively), graphs RXc with the 95, 75 and 50% tolerance intervals of the vectorial value of the impedance, were made through BIVA Software 2002. 150 infants were studied (48,6% girls), term, AGA, exclusively breastfed. The average age was 56,4 (± 23,1) days, average weight was 5038,5g, higher in girls (p = 0,001), and the average length was 56,0 cm (± 0,03), higher in girls (p = 0,001). The values of R (± SD) were 521,2 (± 52,1); 519,4 (± 53,4) and 523,0 (± 51,1) ? and for Xc were 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectively for all the infants, and boys and girls, with no difference between the genders (p = 0,6) and (p = 0,1). Regarding to the phase angle, we found normal value of 4,3° (± 0,7°) for all the infants, 4,3° (± 0,6°) for male and 4,4° (± 0,5°) for female, without statistical difference (p = 0,36). For Bioelectrical Impedance Vector analysis of infants from 30 to 90 days of life, it would be interesting to use specific reference values for this age group and gender. BIVA model makes possible the direct comparison of the measured vector of the small children; still makes it possible for children needing special care, using the tolerance reference values of healthy infants. This comparison allows us a qualitative assessment of the body composition, with no need of equations. With the values of phase angle characterized in the present study for healthy Brazilian infants, from 30 to 90 days of life, critical patients data can be compared, being useful during the hospitalization due to severe illness.

Submitted by PPG Pediatria e Sa?de da Crian?a (pediatria-pg@pucrs.br) on 2018-05-21T13:54:31Z No. of bitstreams: 1 Tese_Eduardo_Mundstock Versao Final.pdf: 1978473 bytes, checksum: 4be8f1b605788a6e254263a3c448a60f (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-06-06T18:34:35Z (GMT) No. of bitstreams: 1 Tese_Eduardo_Mundstock Versao Final.pdf: 1978473 bytes, checksum: 4be8f1b605788a6e254263a3c448a60f (MD5) / Made available in DSpace on 2018-06-06T18:36:11Z (GMT). No. of bitstreams: 1 Tese_Eduardo_Mundstock Versao Final.pdf: 1978473 bytes, checksum: 4be8f1b605788a6e254263a3c448a60f (MD5) Previous issue date: 2018-03-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Introduction: The phase angle is considered an important prognostic marker because it reflects cellular health. Inadequate physical activity and sitting time are associated with a significant number of chronic noncommunicable diseases. Recent studies suggest that these two factors may be associated with phase angle values. Objective: to verify the association of phase angle with physical activity Methodology: the thesis will present two articles: a systematic review with metaanalysis and a cross-section article. Meta-analysis: We searched the following databases: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, SciELO, LILACS, SPORTDiscus, Scopus and Web of Science. Two reviewers independently assessed eligibility criteria and bias risks. The results were synthesized using random effects models. The association between physical activity and phase angle was evaluated considering the design of the study. Cross-sectional study: individuals over 11 years of age, of both sexes, who met bioimpedance assessment criteria and without diagnosis of chronic disease, were invited to participate in the study. The phase angle evaluation was performed using Ottoboni's Biospace equipment, model InBodyS10. Physical activity level and sitting time were assessed using the International Physical Activity Questionnaire (IPAQ). The association between the phase angle and the predictor variables was evaluated using a univariate and multivariate generalized linear model (GLM). All variables with a value of p <0.20 were included in the multivariate model. In the final model, only the variables with p <0.05 were included. Results: Systematic Review: Nine studies, totaling 575 participants, were included in the meta-analysis. The results of cross-sectional studies indicate that the active subjects presented a mean value of higher phase angle when compared to controls (DM = 0.70, 95% CI 0.48 to 0.92, P <0.001), with low heterogeneity (I2 = 0%, P = 0.619). In the crosssectional analysis, the differences between health status and type of physical activity evaluation were not significant (P = 0.332, P <0.253). In longitudinal studies (clinical trial and follow-up), mean values of final phase angle increased significantly compared to baseline (DM = 0.30, 95% CI 0.11 to 0.49, P <0.001), with low heterogeneity (I2 = 13%, P = 0.331). The differences were not significant in relation to the state of health and the type of longitudinal study (clinical trials or follow-up studies) (P = 0.900; 0.989). Evidence of publication bias was not observed, and the overall risk of bias was moderate to high. Cross-sectional article: 1228 subjects were included. The multivariate generalized linear model showed that both physical activity (? = 0.164, 95% CI 0.071 to 0.256, P = 0.001) and sitting time (? = 0.152, 95% CI 0.063 to 0, 242, P = 0.001) were determinant for the phase angle. As well as sex, body mass index and age, also remained associated with phase angle (? = -0.890, 95%CI -0.975 to -0.806, P <0.001; ? = 0.037, 95%CI 0.029 to 0,045, p <0.001 e; ? = -0.006, 95%CI -0.008 to -0.003 P<0.001, respectively). Conclusion: The results of the systematic review and the cross-sectional article suggest an association of phase angle with physical activity and sitting time. Among the main factors that may explain the positive effect of physical activity on the phase angle are the increase in cell membrane integrity and the change in intracellular content, these factors reflecting the cellular health and, consequently, the health of the individual. / Introdu??o: O ?ngulo de fase est? sendo considerado um importante marcador progn?stico, pois reflete a sa?de celular. A atividade f?sica inadequada e o tempo sentado est?o associados a um n?mero importante de doen?as cr?nicas n?o transmiss?veis. Estudos recentes sugerem que esses dois fatores podem estar associados com os valores do ?ngulo de fase. Objetivo: verificar a associa??o do ?ngulo de fase com a atividade f?sica. Metodologia: a tese ir? apresentar dois artigos: uma revis?o sistem?tica com metan?lise e um artigo transversal. Metan?lise: foram realizadas buscas nas seguintes bases de dados: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, SciELO, LILACS, SPORTDiscus, Scopus e Web of Science. Dois revisores avaliaram independentemente os crit?rios de elegibilidade e o risco de vi?s. Os resultados foram sintetizados mediante modelos de efeitos aleat?rios. A associa??o entre atividade f?sica e ?ngulo de fase foi avaliada considerando o desenho do estudo. Artigo transversal: os indiv?duos com mais de 11 anos de idade, de ambos os sexos, que atendiam aos crit?rios de avalia??o da bioimped?ncia e sem diagn?stico de doen?a cr?nica, foram convidados a participar do estudo. A avalia??o do ?ngulo de fase foi realizada usando o equipamento Biospace, modelo InBodyS10, da Ottoboni. O n?vel de atividade f?sica e o tempo sentado foram avaliados com o question?rio internacional de atividade f?sica (IPAQ). A associa??o entre o ?ngulo de fase e as vari?veis preditoras foram avaliadas utilizando um modelo linear generalizado univari?vel e multivari?vel (MLG). Todas as vari?veis com um valor de p <0,20 foram inclu?das no modelo multivari?vel. No modelo final, apenas as vari?veis com p <0,05 foram inclu?das. Resultados: Revis?o Sistem?tica: Nove estudos, totalizando 575 participantes, foram inclu?dos na metan?lise. Os resultados dos estudos transversais indicam que os sujeitos ativos apresentaram um valor m?dio de ?ngulo de fase superior quando comparado aos controles (DM = 0,70; IC 95%: 0,48 a 0,92, P <0,001), com baixa heterogeneidade (I2 = 0%; P = 0,619). Na an?lise transversal, as diferen?as entre o estado de sa?de e o tipo de avalia??o da atividade f?sica n?o foram significativas (P = 0,332; P <0,253). Nos estudos longitudinais (ensaio cl?nico e acompanhamento), os valores m?dios do ?ngulo de fase finais aumentaram significativamente comparando com os valores iniciais (DM = 0,30; IC 95%: 0,11 a 0,49, P <0,001), com heterogeneidade baixa (I2 = 13%, P = 0,3314). As diferen?as n?o foram significativas, em rela??o ao estado de sa?de e ao tipo de estudo longitudinal (ensaios cl?nicos ou estudos de seguimento) (P = 0,900; 0,989). N?o encontramos evid?ncia de vi?s de publica??o e o risco geral de vieses foi de moderado a alto. Artigo transversal: foram inclu?dos 1228 indiv?duos. O modelo linear generalizado multivari?vel mostrou que tanto a atividade f?sica (? = 0,164, IC95% 0,071 a 0,256, P= 0,001) como o tempo sentado (? = 0,152, IC95% 0,063 a 0,242, P= 0,001) foram determinantes para o ?ngulo de fase. Assim como o sexo, o ?ndice de massa corporal e a idade tamb?m permaneceram associados com o ?ngulo de fase (? = -0,890, IC95% -0,975 a -0,806, P <0,001; ? = 0,037, IC95% 0,029 a 0,045, p <0,001 e; ? = -0,006, IC95% - 0,008 a -0,003 P<0,001, respectivamente). Conclus?o: Os resultados da revis?o sistem?tica e do artigo transversal sugerem uma associa??o do ?ngulo de fase com a atividade f?sica e com o tempo sentado. Entre os principais fatores que podem explicar o efeito positivo da atividade f?sica sobre o ?ngulo de fase est?o o aumento da integridade da membrana celular e a mudan?a no conte?do intracelular, fatores estes que refletem a sa?de celular e, consequentemente, a sa?de do indiv?duo.

Devido às dificuldades encontradas excessivas variabilidades de água no organismo do lactente, considera-se a análise vetorial de impedância bioelétrica (BIVA) um método propício para avaliação da composição corporal. Trata-se de um método que não faz nenhuma pressuposição sobre valores da composição corporal, podendo ser controlado por seus próprios valores, independente de equações ou modelos. Os objetivos deste estudo foram descrever valores de referência e criar curvas de BIVA para lactentes saudáveis de 30 a 90 dias de vida e descrever valores de normalidade de ângulo de fase em lactentes a termo, sadios e adequados para a idade gestacional de 30 a 90 dias de idade, além de comparar os dados de BIVA entre os sexos e entre os existentes na literatura para neonatos e lactentes jovens, com os obtidos neste estudo. Este estudo descritivo transversal avaliou 150 lactentes do Centro Médico Social Comunitário Vila Lobato de Ribeirão Preto - SP - Brasil. Foram coletados dos lactentes os dados antropométricos e a impedância bioelétrica (aparelho de monofrequência RJL System ® modelo Quantum II - 800 ?A e 50 KHz). Usando distribuição bivariável normal de resistência e reactância por comprimento (R/H e Xc/H) do lactente, respectivamente, foram calculados e assim confeccionados os gráficos RXc com os intervalos de tolerância de 95, 75, 50% do valor vetorial da impedância por meio do BIVA Software 2002. Foram avaliados 150 lactentes (48,6% do sexo feminino), nascidos a termo, adequados para idade gestacional e em aleitamento materno exclusivo. A idade média foi 56,4 (± 23,1) dias. O peso médio encontrado foi de 5038,5g (± 902,4), sendo maior no sexo masculino (p = 0,001). Quanto ao comprimento corporal, a média foi 56,0 cm (± 0,03), sendo maior no sexo masculino (p = 0,001). As médias de R (±DP) foram 521,2 (± 52,1); 519,4 (± 53,4) e 523,0 (± 51,1) ?, e para Xc foram 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectivamente para todos os lactentes, e separados por sexo (meninos e meninas), não havendo diferença entre os sexos (p = 0,6) e (p = 0,1). Em relação ao ângulo de fase, encontrou-se o valor de normalidade de 4,3° (± 0,7°) para todos os lactentes, 4,3° (± 0,6°) para os do sexo masculino e 4,4° (± 0,5°) para os do sexo feminino, não havendo diferença estatisticamente significativa (p = 0,3). Para a análise vetorial de lactentes de 30 a 90 dias de idade, devem ser utilizados os valores de referência específicos para esta faixa etária e sexo, pois estes se apresentaram diferentes dos descritos na literatura. Com o modelo de estudo BIVA torna-se possível a comparação direta do vetor medido na criança pequena ou com necessidade de cuidados especiais com os intervalos de tolerância de referência de lactentes saudáveis, permitindo uma avaliação qualitativa da composição corporal e sem erro de predição das fórmulas. Com os valores de ângulo de fase caracterizados no presente estudo para lactentes brasileiros saudáveis, de 30 a 90 dias de idade, dados de pacientes críticos podem ser comparados, sendo útil durante a internação e acompanhamento de pacientes graves. / Bioelectrical impedance vectorial analysis (BIVA) can be considered a favorable method for evaluation of the body composition, due to the difficulties in the early life and excessive variability of the amount of water in the organism of the infants. It is a method that doesn\'t make any presumption on values of the body composition, which can be controlled by their own values, with no need for validation based on gold standards, not depending on equations or models. The aims of the study are to establish reference values creating BIVA curves, and to establish reference values for phase angle in term infants, healthy and appropriate-forgestational age (AGA), from 30 to 90 days of life. This study still intend to compare the data of BIVA between genders, among newborns and young infants, presented in the literature, and the ones obtained in this study. This transversal cohort study assessed healthy infants of a Community Centre for Social Medicine Vila Lobato, located in Ribeirão Preto, São Paulo, Brazil. Data of infants, anthropometry and bioelectrical impedance were collected (singlefrequency - RJL System ® model Quantum II - 800 ?A and 50 KHz). Using bivariate normal distribution of R/H and Xc/H (resistance and reactance for infants length, respectively), graphs RXc with the 95, 75 and 50% tolerance intervals of the vectorial value of the impedance, were made through BIVA Software 2002. 150 infants were studied (48,6% girls), term, AGA, exclusively breastfed. The average age was 56,4 (± 23,1) days, average weight was 5038,5g, higher in girls (p = 0,001), and the average length was 56,0 cm (± 0,03), higher in girls (p = 0,001). The values of R (± SD) were 521,2 (± 52,1); 519,4 (± 53,4) and 523,0 (± 51,1) ? and for Xc were 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectively for all the infants, and boys and girls, with no difference between the genders (p = 0,6) and (p = 0,1). Regarding to the phase angle, we found normal value of 4,3° (± 0,7°) for all the infants, 4,3° (± 0,6°) for male and 4,4° (± 0,5°) for female, without statistical difference (p = 0,36). For Bioelectrical Impedance Vector analysis of infants from 30 to 90 days of life, it would be interesting to use specific reference values for this age group and gender. BIVA model makes possible the direct comparison of the measured vector of the small children; still makes it possible for children needing special care, using the tolerance reference values of healthy infants. This comparison allows us a qualitative assessment of the body composition, with no need of equations. With the values of phase angle characterized in the present study for healthy Brazilian infants, from 30 to 90 days of life, critical patients data can be compared, being useful during the hospitalization due to severe illness.

The main objective of this research was to exploit the interrelations between the rheological behavior and nano-microstructure of complex fluids in solving two state-of-the-art problems, one in the field of biomedical engineering: controlling the amount and characteristics of bioaerosol droplets generated during coughing, and the other in the bitumen-heavy oil industry: characterizing the nano-microstructure of asphaltene particles in bitumen and heavy oil from their rheological behavior. For the first problem, effect of viscoelastic and surface properties of artificial mucus simulant gels on the size distribution and amount of airborne bioaerosol droplets generated during simulated coughing were investigated. The results revealed that suppressing the generation of bioaerosol droplets and/or reducing the number of emitted droplets to a minimum during coughing are practically achievable through modulation of mucus viscoelastic properties. While variation of surface tension did not show any change in the droplet size distribution, an increase in particle size was observed as the samples changed from elastic solid type to viscoelastic type to viscous fluid type samples. This knowledge will help in the development of a new class of drugs being developed at the University of Alberta, aimed at controlling the transmission of airborne epidemic diseases by modifying the viscoelastic properties of mucus. For the second problem, studies of viscoelastic behavior of Athabasca bitumen (Alberta) and Maya crude (Mexico) oil samples, along with their Nano-filtered and chemically separated-plus-reconstituted samples were performed. The results revealed that the rheological behaviors of the bitumen-heavy oil samples are governed by their multiphase nature. The rheological behavior of all feeds, permeates and retentate samples followed a single master curve over the entire temperature interval, consistent with that of a slurry comprising a Newtonian liquid plus a dispersed solid comprising non-interacting hard spheres. The behavior of asphaltenes in the reconstituted samples, however, was found to be significantly different from that in nanofiltered samples. The information about the characteristics and behaviors of asphaltenes obtained in this study will help better understand the asphaltene structures, and support the effort to determine solutions for numerous asphaltene-related industrial problems. In the long run, this knowledge will help to create more efficient extraction and upgrading processes for bitumen and heavy oils. / Thermo Fluids

Rotordynamic instability can be disastrous for the operation of high speed turbomachinery in the industry. Most ??instabilities?? are due to de-stabilizing cross coupled forces from variable fluid dynamic pressure around a rotor component, acting in the direction of the forward whirl and causing subsynchronous orbiting of the rotor. However, all subsynchronous whirling is not unstable and methods to diagnose the potentially unstable kind are critical to the health of the rotor-bearing system. The objective of this thesis is to explore means of diagnosing whether subsynchronous vibrations are benign or have the potential to become unstable. Several methods will be detailed to draw lines of demarcation between the two. Considerable focus of the research has been on subharmonic vibrations induced from non-linear bearing stiffness and the study of vibration signals typical to such cases. An analytical model of a short-rigid rotor with stiffness non-linearity is used for numerical simulations and the results are verified with actual experiments. Orbits filtered at the subsynchronous frequency are shown as a diagnostic tool to indicate benign vibrations as well as ??frequency tracking?? and agreement of the frequency with known eigenvalues. Several test rigs are utilized to practically demonstrate the above conclusions. A remarkable finding has been the possibility of diagnosing instability using the synchronous phase angle. The synchronous phase angle ?? is the angle by which the unbalance vector leads the vibration vector. Experiments have proved that ?? changes appreciably when there is a de-stabilizing cross coupled force acting on the rotor as compared to when there is none. A special technique to calculate the change in ?? with cross-coupling is outlined along with empirical results to exemplify the case. Subsequently, a correlation between the synchronous phase angle and the phase angle measured with most industrial balancing instruments is derived so that the actual measurement of the true phase angle is not a necessity for diagnosis. Requirements of advanced signal analysis techniques have led to the development of an extremely powerful rotordynamic measurement teststand ?? ??LVTRC??. The software was developed in tandem with this thesis project. It is a stand-alone application that can be used for field measurements and analysis by turbomachinery companies.

Modern turbomachines are designed towards thinner, lighter and highly loaded blades. This gives rise to increased sensitivity to flow induced vibrations such as flutter, which leads to structure failure in a short period of time if not sufficiently damped. Although numerical tools are more and more reliable, flutter prediction still depends on a large degree on simplified models. In addition, the critical nature of flutter, resulting in poor well-documented real cases in the open literature, and the lack of experimental database typical of engine flows make its apprehension even more challenging.  In that context, the present thesis is dedicated to study flutter in recent turbines through aerodynamic analysis of subsonic or supersonic flows in response to a prescribed vibratory mode of the structure. The objective is to highlight some mechanisms potentially responsible for flutter in order to be in better position when designing blades. The strategy consists in leading both experimental and numerical investigations.  The experimental part is based on a worldwide unique annular turbine sector cascade employed for measuring the aeroelastic response by means of the aerodynamic influence coefficient technique. The cascade comprises seven low pressure gas turbine blades one of which can oscillate in a controlled way as a rigid body. Aeroelastic responses are measured at various mechanical and aerodynamic parameters: pure and combined modeshapes, reduced frequency, Mach number, incidence angle. In addition to turbulence level measurements, the database aims at assessing the influence of these parameters on the aerodynamic damping, at validating the linear combination principle and at providing input for numerical tools. The numerical part is based on unsteady computations linearized in the frequency domain and performed in the traveling wave mode. The focus is put on two industrial space turbines: 2D computations are performed on an integrally bladed disk, also called blisk; its very low viscous material damping results in complex motions with combined modes and extremely high reduced frequency. The blisk operates at low subsonic conditions without strong non-linearities. Although the blades have been predicted aeroelastically stable, an original methodology based on elementary decompositions of the blade motion is presented to identify the destabilizing movements. The results suggest that the so-called classical flutter is surprisingly prone to occur. Moreover, the aerodynamic damping has been found extremely sensitive to the interblade phase angle and cut-on/cut-off conditions. 3D computations are then performed on a supersonic turbine, which features shock waves and boundary layer separation. In contrast, the blade motion is of elementary nature, i.e. purely axial. The blades have been predicted aeroelastically unstable for backward traveling waves and stable for forward traveling waves. The low reduced frequencies allow quasi-steady analysis, which still account for flutter mechanisms: the shock wave motion establishes the boundary between stable and unstable configurations. / <p>QC 20111209</p>

This study focuses on developing structural health monitoring techniques to detect damage in deepwater risers subjected to vortex-induced vibration (VIV), and studying vibration control strategies to extend the service life of offshore structures. Vibration-based damage detection needs both responses from the undamaged and damaged deepwater risers. Because no experimental data for damaged deepwater risers is available, a model to predict the VIV responses of deepwater risers with given conditions is needed, which is the forward problem. In this study, a new three dimensional (3D) analytical model is proposed considering coupled VIV (in-line and cross-flow) for top-tensioned riser (TTR) with wake oscillators. The model is verified by direct numerical simulations and experimental data. The inverse problem is to detect damage using VIV responses from the analytical models with/without damage, where the change between dynamic properties obtained from riser responses represents damage. The inverse problem is performed in two steps: blind identification and damage detection. For blind identification, a wavelet modified second order blind identification (WMSOBI) method and a complex WMSOBI (CWMSOBI) method are proposed to extract modal properties from output only responses for standing and traveling wave vibration, respectively. Numerical simulations and experiments validate the effectiveness of proposed methods. For damage detection, a novel weighted distribution force change (WDFC) index (for standing wave) and a phase angle change (PAC) index (for traveling wave) are proposed and proven numerically. Experiments confirm that WDFC can accurately locate damage and estimate damage severity. Furthermore, a new fatigue damage estimation method involving WMSOBI, S-N curve and Miner's rule is proposed and proven to be effective using field test data. Vibration control is essential to extend the service life and enhance the safety of offshore structures. Literature review shows that semi-active control devices are potentially a good solution. A novel semi-active control strategy is proposed to tune the damper properties to match the dominant frequency of the structural response in real-time. The effectiveness of proposed strategy in vibration reduction for deepwater risers and offshore floating wind turbines is also validated through numerical studies.

Rotordynamic instability can be disastrous for the operation of high speed turbomachinery in the industry. Most ??instabilities?? are due to de-stabilizing cross coupled forces from variable fluid dynamic pressure around a rotor component, acting in the direction of the forward whirl and causing subsynchronous orbiting of the rotor. However, all subsynchronous whirling is not unstable and methods to diagnose the potentially unstable kind are critical to the health of the rotor-bearing system. The objective of this thesis is to explore means of diagnosing whether subsynchronous vibrations are benign or have the potential to become unstable. Several methods will be detailed to draw lines of demarcation between the two. Considerable focus of the research has been on subharmonic vibrations induced from non-linear bearing stiffness and the study of vibration signals typical to such cases. An analytical model of a short-rigid rotor with stiffness non-linearity is used for numerical simulations and the results are verified with actual experiments. Orbits filtered at the subsynchronous frequency are shown as a diagnostic tool to indicate benign vibrations as well as ??frequency tracking?? and agreement of the frequency with known eigenvalues. Several test rigs are utilized to practically demonstrate the above conclusions. A remarkable finding has been the possibility of diagnosing instability using the synchronous phase angle. The synchronous phase angle ?? is the angle by which the unbalance vector leads the vibration vector. Experiments have proved that ?? changes appreciably when there is a de-stabilizing cross coupled force acting on the rotor as compared to when there is none. A special technique to calculate the change in ?? with cross-coupling is outlined along with empirical results to exemplify the case. Subsequently, a correlation between the synchronous phase angle and the phase angle measured with most industrial balancing instruments is derived so that the actual measurement of the true phase angle is not a necessity for diagnosis. Requirements of advanced signal analysis techniques have led to the development of an extremely powerful rotordynamic measurement teststand ?? ??LVTRC??. The software was developed in tandem with this thesis project. It is a stand-alone application that can be used for field measurements and analysis by turbomachinery companies.

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