A coordenação espaço-temporal dos movimentos dos braços de nadadores competitivos tem demonstrado ser um importante fator ligado a velocidade de nado e ao desempenho desses atletas. Os modelos básicos de coordenação comumente percebidos são: (1) captura - caracterizado pela existência de períodos sem propulsão entre a execução de cada braçada; (2) oposição - o movimento propulsivo de um braço inicia no exato instante em que o braço contra-lateral finaliza a fase propulsiva de seu movimento; (3) sobreposição - caracterizado por períodos com ação propulsiva simultânea dos dois braços. O objetivo deste estudo foi comparar os resultados da análise da simetria e da coordenação do nado crawl obtidos por meio dos métodos de cinemetria e dinamometria durante testes de nado livre e nado amarrado. Foram avaliados 13 nadadores federados voluntários do sexo masculino (idade: 19,4 ± 5,3 anos, estatura: 179,0 ± 5,2 cm, envergadura: 188,1 ± 6,0 cm, massa: 70,5 ± 8,7 kg, desempenho: 78,5 ± 4,2 % do recorde mundial de 50 m livres). Para obtenção das demais variáveis do estudo os nadadores foram submetidos à execução de dois protocolos distintos, realizados em piscina 25 m: (A) nado livre: 50 m nadados na máxima velocidade, com partida de dentro da piscina. Os atletas tiveram seu nado filmado (50 Hz) por duas câmeras colocadas dentro da água, uma em cada borda lateral da piscina, que foram deslocadas por operadores treinados a uma velocidade semelhante à velocidade de deslocamento do mesmo e (B) nado amarrado: nado estacionário em máxima intensidade com duração semelhante a do teste de nado livre. Os atletas tiveram a resultante das forças aplicadas por braçada medida por um transdutor de força fixado a borda da piscina onde era preso o cabo que estava ligado as suas cinturas e seus nados filmados (50 Hz) por duas câmeras posicionadas lateralmente a eles, sob a água. Um módulo eletrônico de sincronismo foi utilizado para disparar, simultaneamente, um sinal luminoso nas duas filmadoras e um pulso elétrico no sistema de aquisição dos dados oriundos do transdutor de força, possibilitando a posterior análise dos sinais oriundos de todos os aparatos utilizados para coleta dos dados. A partir da análise das imagens obtidas durante a execução de ambos os protocolos foram mensurados o índice de coordenação de nado (IdC), para ambos os braços (IdC1 e IdC2), em nado livre e nado amarrado e a freqüência média de braçadas (FB) na primeira e segunda metades do teste executado durante a aplicação de cada um dos protocolos. Os dados oriundos do transdutor de força permitiram a mensuração da diferença de tempo entre os picos de força aplicada por braçada (DFTA) para ambos os braços (DTFA1 e DTFA2). Os resultados mostraram um menor valor médio de IdC apresentado durante no nado livre (-3,59 ± 8,63 %) em relação ao nado amarrado (0,59 ± 7,92 %) indicando que, ao executarem o nado livre, os atletas adotam uma coordenação no modelo de captura e ao executarem o nado amarrado adotam uma coordenação em sobreposição, porém com valores que indicam uma possível coordenação no modelo de oposição. Diferentes valores de IdC1 (- 0,36 ± 7,44 %) e IdC2 (- 6,94 ± 8,52 %) foram encontrados em nado livre e nado amarrado (IdC1 = 3,76 ± 8,27 % e IdC2 = -2,54 ± 6,12 %). Os valores de FB apresentados pelos atletas na primeira metade de cada um dos testes foram significativamente mais elevados do que os valores de FB apresentados na segunda metade do respectivo teste (nado livre: [t(12) = 6,996; p < 0,001]; nado amarrado: [t(12) = 3,026; p = 0,011]). A comparação entre os valores de IdC1 e IdC2 adotados durante a execução de cada um dos protocolos mostrou que, durante o nado amarrado, todos os sujeitos apresentaram coordenação assimétrica enquanto durante o nado livre apenas três, dos 13 avaliados, foram considerados simétricos. A comparação entre os valores de DTFA1 e 2 demonstrou que apenas quatro sujeitos foram simétricos. A comparação dos valores da FB adotada pelos atletas mostrou que significativos maiores valores de FB foram apresentados durante o nado livre (FBiniL = 0,95 ± 0,08 ciclos.s-1, FBfinL = 0,88 ± 0,08 ciclos.s-1) em ralação ao nado amarrado (FBiniA = 0,79 ± 0,09 ciclos.s- 1, FBfinA = 0,76 ± 0,10 ciclos.s-1) na primeira e na segunda metades de ambos os testes. As comparações entre os valores de IdC apresentados durante nado livre e nado amarrado indicaram que apenas quatro, dos 13 sujeitos avaliados, mantiveram semelhantes valores para IdC1 e 2 em ambas as situações de nado. Apenas 3 dos sujeitos avaliados apresentaram valores significativos de correlação entre as variáveis IdC e DTFA. Com base nos achados deste estudo concluiu-se que: (1) durante os 50 m livres executados em máxima velocidade, os nadadores apresentaram, em média, uma coordenação no modelo de captura; (2) durante o nado amarrado os avaliados apresentaram uma coordenação em sobreposição, muito próxima da oposição; (3) o IdC e a FB medidas durante o nado livre foram diferentes das medidas durante o nado amarrado, indicando alterações da técnica; (4) a maioria dos nadadores avaliados manteve uma coordenação de nado considerada assimétrica em ambas as situações testadas e (5) a DTFA não se configurou como um parâmetro aceitável para determinação das simetrias e do modelo de coordenação de nado adotados durante o nado livre. Futuras investigações a cerca deste tema se fazem necessárias. / The spatial-temporal and coordinative structures of arms movements in competitive swimmers has been shown to be an important factor associated with swimming speed and performance of these athletes. The basic models of coordination commonly quoted are: (1) catch-up - describes a lag time between the propulsive forces of the two arms; (2) opposition - the propulsive phase of one arm begins when the other arm has just finished its propulsive phase; (3) superposition - describes an overlap of the propulsive phases of the two arms. The aim of this study was to compare the symmetry and the coordination analysis of front crawl swimming obtained through the kinematic and kinetic methods of free and tethered front crawl swimming. Thirteen male competitive swimmers volunteered this investigation (age: 19,4 ± 5,3 years, height: 179,0 ± 5,2 cm, arm span: 188,1 ± 6,0 cm, weight: 70,5 ± 8,7 kg, performance: 78,5 ± 4,2 % of world record at 50 m free style). Subjects underwent two different test protocols, both in a 25m indoor pool: (A) front crawl stroke: 50 m maximum swimming test, starting inside the pool. The athletes were recorded during all the test (50 Hz) by two underwater cameras, one on each lateral side of the pool, being transported by two experienced investigators at a speed equal to that of the swimmer, and (B) tethered swimming: tethered swimming at maximal intensity for the same period of the previous 50 m maximum test. Resultant force applied during each stroke was recorded by a force transductor attached on one side to the wall of the pool and on the other side to an inextensible cable that was attached to the swimmer's hips. The test was recorded during (50 Hz) by two underwater cameras, one on each lateral side of the swimmer. An electronic synchronization module was used to fire a LED light on both cameras and an electric pulse to the force acquisition recorder of the force transductor at the same time, this way allowing for correct interpretation of all data. From the images analysis of both protocols, we measured the index of coordination (IdC) for both arms (IdC1 and IdC2) during front crawl swimming and tethered swimming and the average stroke rate (SR) for the first and second half of both protocols. The data from the force transductor allowed for the determination of the time difference between the peak force applied per stroke (PFAS) for each arm (PFAS1 and PFAS2). The results show a smaller IdC mean for front-crawl stroke (-3,59 ± 8,63 %) compared to tethered swimming (0,59 ± 7,92 %), indicting that during front-crawl stroke the athletes prefer a catch-up coordination model, and during the tethered swimming condition they use a superposition coordination model, although some values suggest that some swimmers adopts opposition model during tethered swimming. Different values of IdC1 (-0,36 ± 7,44 %) and IdC2 (- 6,94 ± 8,52 %) were found for front-crawl and tethered swimming (IdC1 = 3,76 ± 8,27 % and IdC2 = -2,54 ± 6,12 %). Values of SR for the first half were higher than for the second half, irrespective of test condition (front-crawl: [t(12) = 6,996; p < 0,001]; tethered swimming: [t(12) = 3,026; p = 0,011]). Comparison between IdC1 and IdC2 used by athletes during the protocols revealed that during tethered swimming all subjects showed an asymmetric coordination, and during the front-crawl swimming only three subjects were considered symmetric. Comparison of SR values revealed significantly higher values for free swimming condition (SRiniF = 0,95 ± 0,08 stroke.s-1, SRfinF = 0,88 ± 0,08 stroke.s-1) compared to tethered swimming condition (SRiniT = 0,79 ± 0,09 stroke.s-1, SRfinT = 0,76 ± 0,10 stroke.s- 1), for both the first and second halves. The comparisons between IdC values of front-crawl and tethered swimming revealed that only four, of thirteen subjects evaluated, did have similar IdC1 and IdC2 values during both tests. Only three subjects showed a significant correlation between IdC and PFAS. Based on the findings of this study it was concluded that: (1) during 50 m front-crawl swimming maximum tests, the swimmers showed, on average, a catch-up coordination model; (2) during tethered swimming the subjects showed a superposition model of coordination, very close to the opposition one; (3) IdC and SR measured during front-crawl swimming were different from those measured during tethered swimming, indicating an alteration on the technique; (4) most of the swimmers tested showed an asymmetric coordination during both tests and (5) PFAS did not reveal as an acceptable parameter for determination of (as)symmetry and model of coordination during front-crawl swimming. Further investigations about this topic are required.

A coordenação espaço-temporal dos movimentos dos braços de nadadores competitivos tem demonstrado ser um importante fator ligado a velocidade de nado e ao desempenho desses atletas. Os modelos básicos de coordenação comumente percebidos são: (1) captura - caracterizado pela existência de períodos sem propulsão entre a execução de cada braçada; (2) oposição - o movimento propulsivo de um braço inicia no exato instante em que o braço contra-lateral finaliza a fase propulsiva de seu movimento; (3) sobreposição - caracterizado por períodos com ação propulsiva simultânea dos dois braços. O objetivo deste estudo foi comparar os resultados da análise da simetria e da coordenação do nado crawl obtidos por meio dos métodos de cinemetria e dinamometria durante testes de nado livre e nado amarrado. Foram avaliados 13 nadadores federados voluntários do sexo masculino (idade: 19,4 ± 5,3 anos, estatura: 179,0 ± 5,2 cm, envergadura: 188,1 ± 6,0 cm, massa: 70,5 ± 8,7 kg, desempenho: 78,5 ± 4,2 % do recorde mundial de 50 m livres). Para obtenção das demais variáveis do estudo os nadadores foram submetidos à execução de dois protocolos distintos, realizados em piscina 25 m: (A) nado livre: 50 m nadados na máxima velocidade, com partida de dentro da piscina. Os atletas tiveram seu nado filmado (50 Hz) por duas câmeras colocadas dentro da água, uma em cada borda lateral da piscina, que foram deslocadas por operadores treinados a uma velocidade semelhante à velocidade de deslocamento do mesmo e (B) nado amarrado: nado estacionário em máxima intensidade com duração semelhante a do teste de nado livre. Os atletas tiveram a resultante das forças aplicadas por braçada medida por um transdutor de força fixado a borda da piscina onde era preso o cabo que estava ligado as suas cinturas e seus nados filmados (50 Hz) por duas câmeras posicionadas lateralmente a eles, sob a água. Um módulo eletrônico de sincronismo foi utilizado para disparar, simultaneamente, um sinal luminoso nas duas filmadoras e um pulso elétrico no sistema de aquisição dos dados oriundos do transdutor de força, possibilitando a posterior análise dos sinais oriundos de todos os aparatos utilizados para coleta dos dados. A partir da análise das imagens obtidas durante a execução de ambos os protocolos foram mensurados o índice de coordenação de nado (IdC), para ambos os braços (IdC1 e IdC2), em nado livre e nado amarrado e a freqüência média de braçadas (FB) na primeira e segunda metades do teste executado durante a aplicação de cada um dos protocolos. Os dados oriundos do transdutor de força permitiram a mensuração da diferença de tempo entre os picos de força aplicada por braçada (DFTA) para ambos os braços (DTFA1 e DTFA2). Os resultados mostraram um menor valor médio de IdC apresentado durante no nado livre (-3,59 ± 8,63 %) em relação ao nado amarrado (0,59 ± 7,92 %) indicando que, ao executarem o nado livre, os atletas adotam uma coordenação no modelo de captura e ao executarem o nado amarrado adotam uma coordenação em sobreposição, porém com valores que indicam uma possível coordenação no modelo de oposição. Diferentes valores de IdC1 (- 0,36 ± 7,44 %) e IdC2 (- 6,94 ± 8,52 %) foram encontrados em nado livre e nado amarrado (IdC1 = 3,76 ± 8,27 % e IdC2 = -2,54 ± 6,12 %). Os valores de FB apresentados pelos atletas na primeira metade de cada um dos testes foram significativamente mais elevados do que os valores de FB apresentados na segunda metade do respectivo teste (nado livre: [t(12) = 6,996; p < 0,001]; nado amarrado: [t(12) = 3,026; p = 0,011]). A comparação entre os valores de IdC1 e IdC2 adotados durante a execução de cada um dos protocolos mostrou que, durante o nado amarrado, todos os sujeitos apresentaram coordenação assimétrica enquanto durante o nado livre apenas três, dos 13 avaliados, foram considerados simétricos. A comparação entre os valores de DTFA1 e 2 demonstrou que apenas quatro sujeitos foram simétricos. A comparação dos valores da FB adotada pelos atletas mostrou que significativos maiores valores de FB foram apresentados durante o nado livre (FBiniL = 0,95 ± 0,08 ciclos.s-1, FBfinL = 0,88 ± 0,08 ciclos.s-1) em ralação ao nado amarrado (FBiniA = 0,79 ± 0,09 ciclos.s- 1, FBfinA = 0,76 ± 0,10 ciclos.s-1) na primeira e na segunda metades de ambos os testes. As comparações entre os valores de IdC apresentados durante nado livre e nado amarrado indicaram que apenas quatro, dos 13 sujeitos avaliados, mantiveram semelhantes valores para IdC1 e 2 em ambas as situações de nado. Apenas 3 dos sujeitos avaliados apresentaram valores significativos de correlação entre as variáveis IdC e DTFA. Com base nos achados deste estudo concluiu-se que: (1) durante os 50 m livres executados em máxima velocidade, os nadadores apresentaram, em média, uma coordenação no modelo de captura; (2) durante o nado amarrado os avaliados apresentaram uma coordenação em sobreposição, muito próxima da oposição; (3) o IdC e a FB medidas durante o nado livre foram diferentes das medidas durante o nado amarrado, indicando alterações da técnica; (4) a maioria dos nadadores avaliados manteve uma coordenação de nado considerada assimétrica em ambas as situações testadas e (5) a DTFA não se configurou como um parâmetro aceitável para determinação das simetrias e do modelo de coordenação de nado adotados durante o nado livre. Futuras investigações a cerca deste tema se fazem necessárias. / The spatial-temporal and coordinative structures of arms movements in competitive swimmers has been shown to be an important factor associated with swimming speed and performance of these athletes. The basic models of coordination commonly quoted are: (1) catch-up - describes a lag time between the propulsive forces of the two arms; (2) opposition - the propulsive phase of one arm begins when the other arm has just finished its propulsive phase; (3) superposition - describes an overlap of the propulsive phases of the two arms. The aim of this study was to compare the symmetry and the coordination analysis of front crawl swimming obtained through the kinematic and kinetic methods of free and tethered front crawl swimming. Thirteen male competitive swimmers volunteered this investigation (age: 19,4 ± 5,3 years, height: 179,0 ± 5,2 cm, arm span: 188,1 ± 6,0 cm, weight: 70,5 ± 8,7 kg, performance: 78,5 ± 4,2 % of world record at 50 m free style). Subjects underwent two different test protocols, both in a 25m indoor pool: (A) front crawl stroke: 50 m maximum swimming test, starting inside the pool. The athletes were recorded during all the test (50 Hz) by two underwater cameras, one on each lateral side of the pool, being transported by two experienced investigators at a speed equal to that of the swimmer, and (B) tethered swimming: tethered swimming at maximal intensity for the same period of the previous 50 m maximum test. Resultant force applied during each stroke was recorded by a force transductor attached on one side to the wall of the pool and on the other side to an inextensible cable that was attached to the swimmer's hips. The test was recorded during (50 Hz) by two underwater cameras, one on each lateral side of the swimmer. An electronic synchronization module was used to fire a LED light on both cameras and an electric pulse to the force acquisition recorder of the force transductor at the same time, this way allowing for correct interpretation of all data. From the images analysis of both protocols, we measured the index of coordination (IdC) for both arms (IdC1 and IdC2) during front crawl swimming and tethered swimming and the average stroke rate (SR) for the first and second half of both protocols. The data from the force transductor allowed for the determination of the time difference between the peak force applied per stroke (PFAS) for each arm (PFAS1 and PFAS2). The results show a smaller IdC mean for front-crawl stroke (-3,59 ± 8,63 %) compared to tethered swimming (0,59 ± 7,92 %), indicting that during front-crawl stroke the athletes prefer a catch-up coordination model, and during the tethered swimming condition they use a superposition coordination model, although some values suggest that some swimmers adopts opposition model during tethered swimming. Different values of IdC1 (-0,36 ± 7,44 %) and IdC2 (- 6,94 ± 8,52 %) were found for front-crawl and tethered swimming (IdC1 = 3,76 ± 8,27 % and IdC2 = -2,54 ± 6,12 %). Values of SR for the first half were higher than for the second half, irrespective of test condition (front-crawl: [t(12) = 6,996; p < 0,001]; tethered swimming: [t(12) = 3,026; p = 0,011]). Comparison between IdC1 and IdC2 used by athletes during the protocols revealed that during tethered swimming all subjects showed an asymmetric coordination, and during the front-crawl swimming only three subjects were considered symmetric. Comparison of SR values revealed significantly higher values for free swimming condition (SRiniF = 0,95 ± 0,08 stroke.s-1, SRfinF = 0,88 ± 0,08 stroke.s-1) compared to tethered swimming condition (SRiniT = 0,79 ± 0,09 stroke.s-1, SRfinT = 0,76 ± 0,10 stroke.s- 1), for both the first and second halves. The comparisons between IdC values of front-crawl and tethered swimming revealed that only four, of thirteen subjects evaluated, did have similar IdC1 and IdC2 values during both tests. Only three subjects showed a significant correlation between IdC and PFAS. Based on the findings of this study it was concluded that: (1) during 50 m front-crawl swimming maximum tests, the swimmers showed, on average, a catch-up coordination model; (2) during tethered swimming the subjects showed a superposition model of coordination, very close to the opposition one; (3) IdC and SR measured during front-crawl swimming were different from those measured during tethered swimming, indicating an alteration on the technique; (4) most of the swimmers tested showed an asymmetric coordination during both tests and (5) PFAS did not reveal as an acceptable parameter for determination of (as)symmetry and model of coordination during front-crawl swimming. Further investigations about this topic are required.

A coordenação espaço-temporal dos movimentos dos braços de nadadores competitivos tem demonstrado ser um importante fator ligado a velocidade de nado e ao desempenho desses atletas. Os modelos básicos de coordenação comumente percebidos são: (1) captura - caracterizado pela existência de períodos sem propulsão entre a execução de cada braçada; (2) oposição - o movimento propulsivo de um braço inicia no exato instante em que o braço contra-lateral finaliza a fase propulsiva de seu movimento; (3) sobreposição - caracterizado por períodos com ação propulsiva simultânea dos dois braços. O objetivo deste estudo foi comparar os resultados da análise da simetria e da coordenação do nado crawl obtidos por meio dos métodos de cinemetria e dinamometria durante testes de nado livre e nado amarrado. Foram avaliados 13 nadadores federados voluntários do sexo masculino (idade: 19,4 ± 5,3 anos, estatura: 179,0 ± 5,2 cm, envergadura: 188,1 ± 6,0 cm, massa: 70,5 ± 8,7 kg, desempenho: 78,5 ± 4,2 % do recorde mundial de 50 m livres). Para obtenção das demais variáveis do estudo os nadadores foram submetidos à execução de dois protocolos distintos, realizados em piscina 25 m: (A) nado livre: 50 m nadados na máxima velocidade, com partida de dentro da piscina. Os atletas tiveram seu nado filmado (50 Hz) por duas câmeras colocadas dentro da água, uma em cada borda lateral da piscina, que foram deslocadas por operadores treinados a uma velocidade semelhante à velocidade de deslocamento do mesmo e (B) nado amarrado: nado estacionário em máxima intensidade com duração semelhante a do teste de nado livre. Os atletas tiveram a resultante das forças aplicadas por braçada medida por um transdutor de força fixado a borda da piscina onde era preso o cabo que estava ligado as suas cinturas e seus nados filmados (50 Hz) por duas câmeras posicionadas lateralmente a eles, sob a água. Um módulo eletrônico de sincronismo foi utilizado para disparar, simultaneamente, um sinal luminoso nas duas filmadoras e um pulso elétrico no sistema de aquisição dos dados oriundos do transdutor de força, possibilitando a posterior análise dos sinais oriundos de todos os aparatos utilizados para coleta dos dados. A partir da análise das imagens obtidas durante a execução de ambos os protocolos foram mensurados o índice de coordenação de nado (IdC), para ambos os braços (IdC1 e IdC2), em nado livre e nado amarrado e a freqüência média de braçadas (FB) na primeira e segunda metades do teste executado durante a aplicação de cada um dos protocolos. Os dados oriundos do transdutor de força permitiram a mensuração da diferença de tempo entre os picos de força aplicada por braçada (DFTA) para ambos os braços (DTFA1 e DTFA2). Os resultados mostraram um menor valor médio de IdC apresentado durante no nado livre (-3,59 ± 8,63 %) em relação ao nado amarrado (0,59 ± 7,92 %) indicando que, ao executarem o nado livre, os atletas adotam uma coordenação no modelo de captura e ao executarem o nado amarrado adotam uma coordenação em sobreposição, porém com valores que indicam uma possível coordenação no modelo de oposição. Diferentes valores de IdC1 (- 0,36 ± 7,44 %) e IdC2 (- 6,94 ± 8,52 %) foram encontrados em nado livre e nado amarrado (IdC1 = 3,76 ± 8,27 % e IdC2 = -2,54 ± 6,12 %). Os valores de FB apresentados pelos atletas na primeira metade de cada um dos testes foram significativamente mais elevados do que os valores de FB apresentados na segunda metade do respectivo teste (nado livre: [t(12) = 6,996; p < 0,001]; nado amarrado: [t(12) = 3,026; p = 0,011]). A comparação entre os valores de IdC1 e IdC2 adotados durante a execução de cada um dos protocolos mostrou que, durante o nado amarrado, todos os sujeitos apresentaram coordenação assimétrica enquanto durante o nado livre apenas três, dos 13 avaliados, foram considerados simétricos. A comparação entre os valores de DTFA1 e 2 demonstrou que apenas quatro sujeitos foram simétricos. A comparação dos valores da FB adotada pelos atletas mostrou que significativos maiores valores de FB foram apresentados durante o nado livre (FBiniL = 0,95 ± 0,08 ciclos.s-1, FBfinL = 0,88 ± 0,08 ciclos.s-1) em ralação ao nado amarrado (FBiniA = 0,79 ± 0,09 ciclos.s- 1, FBfinA = 0,76 ± 0,10 ciclos.s-1) na primeira e na segunda metades de ambos os testes. As comparações entre os valores de IdC apresentados durante nado livre e nado amarrado indicaram que apenas quatro, dos 13 sujeitos avaliados, mantiveram semelhantes valores para IdC1 e 2 em ambas as situações de nado. Apenas 3 dos sujeitos avaliados apresentaram valores significativos de correlação entre as variáveis IdC e DTFA. Com base nos achados deste estudo concluiu-se que: (1) durante os 50 m livres executados em máxima velocidade, os nadadores apresentaram, em média, uma coordenação no modelo de captura; (2) durante o nado amarrado os avaliados apresentaram uma coordenação em sobreposição, muito próxima da oposição; (3) o IdC e a FB medidas durante o nado livre foram diferentes das medidas durante o nado amarrado, indicando alterações da técnica; (4) a maioria dos nadadores avaliados manteve uma coordenação de nado considerada assimétrica em ambas as situações testadas e (5) a DTFA não se configurou como um parâmetro aceitável para determinação das simetrias e do modelo de coordenação de nado adotados durante o nado livre. Futuras investigações a cerca deste tema se fazem necessárias. / The spatial-temporal and coordinative structures of arms movements in competitive swimmers has been shown to be an important factor associated with swimming speed and performance of these athletes. The basic models of coordination commonly quoted are: (1) catch-up - describes a lag time between the propulsive forces of the two arms; (2) opposition - the propulsive phase of one arm begins when the other arm has just finished its propulsive phase; (3) superposition - describes an overlap of the propulsive phases of the two arms. The aim of this study was to compare the symmetry and the coordination analysis of front crawl swimming obtained through the kinematic and kinetic methods of free and tethered front crawl swimming. Thirteen male competitive swimmers volunteered this investigation (age: 19,4 ± 5,3 years, height: 179,0 ± 5,2 cm, arm span: 188,1 ± 6,0 cm, weight: 70,5 ± 8,7 kg, performance: 78,5 ± 4,2 % of world record at 50 m free style). Subjects underwent two different test protocols, both in a 25m indoor pool: (A) front crawl stroke: 50 m maximum swimming test, starting inside the pool. The athletes were recorded during all the test (50 Hz) by two underwater cameras, one on each lateral side of the pool, being transported by two experienced investigators at a speed equal to that of the swimmer, and (B) tethered swimming: tethered swimming at maximal intensity for the same period of the previous 50 m maximum test. Resultant force applied during each stroke was recorded by a force transductor attached on one side to the wall of the pool and on the other side to an inextensible cable that was attached to the swimmer's hips. The test was recorded during (50 Hz) by two underwater cameras, one on each lateral side of the swimmer. An electronic synchronization module was used to fire a LED light on both cameras and an electric pulse to the force acquisition recorder of the force transductor at the same time, this way allowing for correct interpretation of all data. From the images analysis of both protocols, we measured the index of coordination (IdC) for both arms (IdC1 and IdC2) during front crawl swimming and tethered swimming and the average stroke rate (SR) for the first and second half of both protocols. The data from the force transductor allowed for the determination of the time difference between the peak force applied per stroke (PFAS) for each arm (PFAS1 and PFAS2). The results show a smaller IdC mean for front-crawl stroke (-3,59 ± 8,63 %) compared to tethered swimming (0,59 ± 7,92 %), indicting that during front-crawl stroke the athletes prefer a catch-up coordination model, and during the tethered swimming condition they use a superposition coordination model, although some values suggest that some swimmers adopts opposition model during tethered swimming. Different values of IdC1 (-0,36 ± 7,44 %) and IdC2 (- 6,94 ± 8,52 %) were found for front-crawl and tethered swimming (IdC1 = 3,76 ± 8,27 % and IdC2 = -2,54 ± 6,12 %). Values of SR for the first half were higher than for the second half, irrespective of test condition (front-crawl: [t(12) = 6,996; p < 0,001]; tethered swimming: [t(12) = 3,026; p = 0,011]). Comparison between IdC1 and IdC2 used by athletes during the protocols revealed that during tethered swimming all subjects showed an asymmetric coordination, and during the front-crawl swimming only three subjects were considered symmetric. Comparison of SR values revealed significantly higher values for free swimming condition (SRiniF = 0,95 ± 0,08 stroke.s-1, SRfinF = 0,88 ± 0,08 stroke.s-1) compared to tethered swimming condition (SRiniT = 0,79 ± 0,09 stroke.s-1, SRfinT = 0,76 ± 0,10 stroke.s- 1), for both the first and second halves. The comparisons between IdC values of front-crawl and tethered swimming revealed that only four, of thirteen subjects evaluated, did have similar IdC1 and IdC2 values during both tests. Only three subjects showed a significant correlation between IdC and PFAS. Based on the findings of this study it was concluded that: (1) during 50 m front-crawl swimming maximum tests, the swimmers showed, on average, a catch-up coordination model; (2) during tethered swimming the subjects showed a superposition model of coordination, very close to the opposition one; (3) IdC and SR measured during front-crawl swimming were different from those measured during tethered swimming, indicating an alteration on the technique; (4) most of the swimmers tested showed an asymmetric coordination during both tests and (5) PFAS did not reveal as an acceptable parameter for determination of (as)symmetry and model of coordination during front-crawl swimming. Further investigations about this topic are required.

Orientador: Orival Andries Júnior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-16T18:10:16Z (GMT). No. of bitstreams: 1 Barbosa_AugustoCarvalho_D.pdf: 7576445 bytes, checksum: 04d87ab5c33f1dc5ca635490134e7f67 (MD5) Previous issue date: 2010 / Resumo: O objetivo do presente estudo foi analisar as respostas agudas de parâmetros biomecânicos à utilização de diferentes tamanhos de palmar no nado crawl. Foram selecionados 14 nadadores homens (idade: 20.0 ± 3.7 anos, altura: 1.84 ± 0.08 m, massa corporal: 76.3 ± 8.6 kg, melhor tempo nos 100 m livre: 53.70 ± 0.87 s) competitivos em nível nacional. Para avaliação da força propulsora foram realizados 02 esforços máximos de 10 s no nado completamente atado. Em cada um foram analisadas 08 braçadas consecutivas, de onde se extraiu os valores médios de força pico (Fpico), força média (Fméd), taxa de desenvolvimento de força (TDF), impulso (ImpF), duração da braçada (DUR), tempo para atingir a força pico (TFpico) e força mínima (Fmín). Os nadadores também realizaram 02 esforços máximos na distância de 25m para obtenção da velocidade média em 15m (VM15m) (foram desprezados os 07 primeiros e 03 últimos metros), da frequência (FB15m) e do comprimento de braçadas (CB15m). Ambos os protocolos foram repetidos em 05 situações, a saber: livre de material (LVR), com palmar pequeno (PP, 280 cm²), médio (PM, 352 cm²), grande (PG, 462 cm²) e extragrande (PGG, 552 cm²). A ANOVA one way e o teste de Kruskal-Wallis foram adotados para comparar as situações. Quando detectado um efeito significante, recorreu-se ao teste de post-hoc de Scheffé (dados paramétricos) ou ao teste de Mann-Whitney com ajuste de Bonferroni (dados não-paramétricos) para localização das diferenças. Foi adotado um nível de significância de 5%. O aumento artificial da área da mão possibilitou o deslocamento de uma maior massa de água ocasionando um incremento significante na Fpico nas comparações LVR x PG, LVR x PGG e PP x PGG. Com isso, houve uma diminuição da velocidade da mão, que repercutiu em um aumento da DUR nessas mesmas comparações. Fméd e/ou TDF não apresentaram modificações significantes devido às alterações concomitantes das variáveis cinéticas e temporais que as influenciam. Esse resultado da TDF, aliado ao aumento do ImpF (principal variável associada à velocidade) nas comparações LVR x PG, LVR x PGG e PP x PGG, pode indicar que PG e PGG propiciam o desenvolvimento da propulsão sem ocasionar prejuízos aparentes na capacidade explosiva dos nadadores. O TFpico aumentou de LVR para PGG e PP para PGG devido ao aumento da Fpico e da diminuição da Fmín. A Fmín diminuiu significantemente apenas de LVR para PGG, apontando para uma possível alteração da relação entre o início e término da propulsão de ambos os braços. A ausência de alterações significantes na VM15m pode estar associada ao aumento do arrasto de onda. A FB15m diminuiu significantemente de LVR para PGG e de PP para PGG, enquanto o CB15m apresentou um comportamento exatamente inverso nas mesmas comparações. Conclui-se que, de forma aguda, o tamanho do palmar influencia principalmente a magnitude da força propulsora gerada e o seu comportamento ao longo do tempo / Abstract: The aim of this study was to analyze the acute responses of biomechanical parameters to different sizes of paddles in front-crawl stroke. Fourteen national competitive male swimmers (Age: 20.0 ± 3.7 years, height: 1.84 ± 0.08 m, body mass: 76.3 ± 8.6 kg, 100- m best time: 53.70 ± 0.87 s) volunteered for this investigation. For the propulsive force evaluation, 02 maximum efforts of 10 s were accomplished in the fully tethered swimming. In each effort, 08 consecutive strokes were analyzed to extract the average value of peak force (Fpeak), mean force (Fmean), explosive force (TDF), impulse (ImpF), stroke duration (DUR), time to peak force (TFpeak) and minimum force (Fmin). Additionally, swimmers accomplished two 25-m maximal swimming in order to measure the average velocity in 15 m (VM15m) (first 07 and last 03m were discarded), the stroke rate (SR15m) and the stroke length (SL15m). Both testing protocols were repeated in 05 conditions: conventional swimming (LVR), wearing small (PP, 280 cm²), medium (PM, 352 cm²), large (PG, 462 cm²) and extra-large paddles (PGG, 552 cm²). The one way ANOVA or the Kruskal-Wallis test were adopted for intersituations comparisons. Possible significant differences were detected by Scheffé post-hoc test (for parametric data) or Mann-Whitney test with Bonferroni adjustment (for non-parametric data). The significance level was set at 5%. The artificial enlargement of the hands allowed the swimmers to push off against a bigger mass of water and provided a significant increase of the Fpeak in the comparisons LVR x PG, LVR x PGG and PP x PGG. Because of this, there was also a hand's velocity reduction, which repercuted in a greater DUR in these same comparisons. The Fmean and/or the TDF did not change significantly due to the concomitant modifications of the kinetic and temporal variables that influence them. This result of the TDF, associated to the increase of the ImpF (the main variable related to swimming velocity) in the comparisons LVR x PG, LVR x PGG and PP x PGG, might indicate that PG and PGG propitiate the development of propulsion without any apparent damage in the swimmer's explosiveness. The TFpeak increased from LVR to PGG and from PP to PGG due to the increase of the Fpeak and the decrease of Fmin. The Fmin decrease significantly only from LVR to PGG, pointing to a possible modification in the relation between the beginning and the end of propulsion of both arms. The absence of significant changes in the VM15m might be related to the wave drag increase. The SR15m decrease significantly from LVR to PGG, while the SL15m presented exactly the inverse behavior. It can be concluded that, acutely, the different sizes of hand paddles influence mainly the magnitude of the propulsive force generated and its behavior throughout the time / Doutorado / Ciencia do Desporto / Doutor em Educação Física

siRNA therapy is an emerging technique that reduces protein expression in cells by degrading their mRNAs via the RNA interference pathway (RNAi). Diseases such as cancer often proliferate due to increased protein expression and siRNA therapy offers a new method of treatment for those diseases. Although siRNA therapy has shown success in vitro, it often fails in vivo due to instability in the blood stream. To overcome this limitation, delivery vehicles are necessary for successful transfection of siRNA into target cells and cationic polymers have been widely studied for this purpose. However, complexes between siRNA and delivery vehicles made from cationic polymers exhibit stability issues in the blood stream which results in toxicity and low transfection. This work hypothesizes that improvement of vehicle/siRNA complex stability will improve siRNA transfection efficiency. To test this, the contributions and outcomes of poly(ethylene glycol) [PEG] shell and hydrophobic core modification to a polyethylenimine (PEI) based tethered nanoassemblies (TNAs) were examined. Initially, hydrophobic modification of palmitate (PAL) to the core of the TNA yielded improved transfection efficiency due to an enhanced endosomal escape capability. However, this modification also reduced the TNA/siRNA complex stability. This indicated that the core hydrophobicity must be balanced in order increase stability while increasing transfection efficiency. Additionally, TNAs made from PEG and PEI did not cause transfection in our initial study. The PEG shell density was found to be too great and thereby reduced transfection efficiency. Reducing the PEG density by lowering PEG molecular weight, reducing attachment percentage, and removing small PEI impurities from the synthesis stock increased overall transfection efficiency and unimolecularity of the TNA complexes. This indicated that the shell composition of the TNA must be tuned in order to improve particle design. Further study of the hydrophobically modification to TNAs yielded unintended effects on the transfection efficiency evaluation assay. These particles exhibited an siRNA independent reduction in the reporter protein used to observe transfection, or a false positive effect, that was not previously observed. It was found that this false positive was influence mainly by the hydrophobic group rather than the cationic polymer backbone. Cellular stress was observed in cells dosed with the hydrophobically modified TNAs which lead to over ubiquitination and rapid degradation of the luciferase protein. This demonstrated that core components of TNAs could cause cellular stress and influence interaction outside of the TNA. Overall, this work demonstrates that hydrophobic core and PEG shell modification require balancing and consideration to improve properties of future cationic polymer based siRNA delivery vehicle design.

The BalloonbornE moduLar Utility for profilinG the lower Atmosphere (BELUGA) was deployed in autumn 2021 in the Arctic at the AWIPEV research station in Ny-Ålesund (Svalbard). In-situ profiles of thermodynamic parameters, broadband radiation, turbulence, aerosol particle concentrations, and cloud microphysical structure, were performed. Additionally, samples of ice nucleating particles were collected. Thermal infrared radiation profiles are presented for different cloud conditions. The data provides the base for studying the vertical distribution of cloud radiative effects, and extends the common view of the bi-modal distribution of the Arctic surface energy budget. / Das Fesselballonsystem BalloonbornE moduLar Utility for profilinG the lower Atmosphere (BELUGA) wurde im Herbst 2021 an der Forschungsstation Ny-Ålesund in der Arktis eingesetzt. Es wurden In-situ Profile von thermodynamischen Parametern, breitbandiger Strahlung, Turbulenz, Aerosolpartikelkonzentrationen und der mikrophysikalischer Wolkenstruktur erstellt. Zusätzlich wurden Proben von eiskeimbildenden Partikeln gesammelt. Strahlungsprofile wurden unter verschiedenen Wolkenbedeckungen gemessen und quantifizieren die vertikale Verteilung der Wolkenstrahlungseffekte. Die Profilmessungen erweitern damit die für bodennahe Messungen bekannte modale Verteilung des Energiehaushalts der Arktis.

Lyconadin A is a pentacyclic Lycopodium alkaloid isolated from the club moss Lycopodium companatum with anticancer activity. Our approach sought to incorporate a 7-exo–6-exo acyl radical cyclization cascade to access the bicyclo[5.4.0]undecane framework of lyconadin A. Our studies created methodology for the synthesis of 5-alkyl and 3,5-dialkyl-6-carbomethoxy-2-pyridones and sterically demanding epoxide substrates. These epoxide substrates underwent an unanticipated Payne rearrangement.Cranomycin is a potent antibiotic with antiprotozoal activity. Structurally it is a cyclopentane ring system with substitution at each carbon in the ring. Another interesting structural aspect is the existence of three contiguous quaternary stereocenters including two tertiary alcohols and a tert-alkylamine. Our strategy led to the development of a highly diastereoselective synthesis of vicinal tertiary diol systems. We have successfully synthesized the cyclopentenone system shown above, from which we hope to assemble cranomycin.

Tethered satellite systems (TSS) can be utilized for a wide range of space-based applications, such as satellite formation control and propellantless orbital maneuvering by means of momentum transfer and electrodynamic thrusting. A TSS is a complicated physical system operating in a continuously varying physical environment, so most research on TSS dynamics and control makes use of simplified system models to make predictions about the behavior of the system. In spite of this fact, little effort is ever made to validate the predictions made by these simplified models. In an ideal situation, experimental data would be used to validate the predictions made by simplified TSS models. Unfortunately, adequate experimental data on TSS dynamics and control is not readily available at this time, so some other means of validation must be employed. In this work, we present a validation procedure based on the creation of a top-level computational model, the predictions of which are used in place of experimental data. The validity of all predictions made by lower-level computational models is assessed by comparing them to predictions made by the top-level computational model. In addition to the proposed validation procedure, a top-level TSS computational model is developed and rigorously verified. A lower-level TSS model is used to study the dynamics of the tether in a spinning TSS. Floquet theory is used to show that the lower-level model predicts that the pendular motion and transverse elastic vibrations of the tether are unstable for certain in-plane spin rates and system mass properties. Approximate solutions for the out-of-plane pendular motion are also derived for the case of high in-plane spin rates. The lower-level system model is also used to derive control laws for the pendular motion of the tether. Several different nonlinear control design techniques are used to derive the control laws, including methods that can account for the effects of dynamics not accounted for by the lower-level model. All of the results obtained using the lower-level system model are compared to predictions made by the top-level computational model to assess their validity and applicability to an actual TSS. / Ph. D.

The lack of forage resources in the Sahelian region of Mali is a major constraint to food production and food sufficiency. Madiama commune is located in northern Mali, in the Niger Delta region. Three separate experiments were conducted to investigate ways to improve pasture resources and productivity. The first experiment (2003) was designed to investigate the influence of sheep grazing tethered at two different residual heights on botanical composition, forage biomass and animal performance. Young sheep weighing approximately 18-24 kg were tethered for a certain period of time depending on residual canopy height. Two treatments 3 or 6 cm residual height were each replicated 4 times. Animals were rotated based on canopy height and each tethered animal followed an 8 paddock rotation. Measurements included forage biomass, plant diversity, animal performance, and botanical composition. The forage species found on these pastures were primarily Schoenfeldia gracilis, Panicum laetum, Setaria palludefusca, Eragrostis turgida, Eragrostis tremula, Zornia glauchidiata, Tephrosia pedicellata, and Cynodon spp. Accumulated seasonal forage biomass increased while forage quality declined as the growing season progressed. Treatment had only a slight effect on animal weight gains (1 to 3kg season-1). These results suggest that residual height may not affect livestock gain. The second experiment was designed to investigate the potential of Cassia tora (C. tora) which is an invasive weed in the region as a supplemental feed for livestock. Cassia tora was harvested within the Madiama commune and ensiled with or without additives (water and or honey/sugar) for 60 or 90 days. Harvest occurred at the vegetative stage in year 1 and mature growth stage in year 2. Prior to placing the chopped material in the bags for ensiling, sub-samples of fresh C. tora were obtained for dry matter (DM) and chemical analysis (NDF, ADF, CP, IVDMD and TDN). In year 1, the ensiled material/fresh material across treatments and locations had NDF varying from 48 to 56 %/ 56 to 57%, ADF from 34 to 41 %/40 to 42%, CP from 9 to 10 %/9 to 23%, and IVDMD from 53 to 64 %/52 to 54%. In year 2, CP averaged twice as much as year 1 with significantly less fiber probably due to the fact that harvest occurred at the vegetative stage. Addition of water or sugar/honey improved the nutritive values of the ensiled material. These results suggest that C. tora can be a reliable feed source during the dry season. A greenhouse experiment was conducted using various P sources (Tilemsi phosphate rock (TPR), North Carolina phosphate rock (NCPR), Aluminum phosphate (AlP), Iron phosphate (FeP), and Triple superphosphate (TSP) and rates (0, 20, 40, 60, and 80 mg P kg-1 soil). Plants were grown for 10 wks, harvested and separated into above and below ground plant parts. The root and plant material were dried, ground and analyzed for elemental P. The result showed variable P solubility and uptake by the plant. Overall, addition of P resulted in an increase in above ground biomass as well as root mass compared with the untreated control. Field and greenhouse experiments showed that in the Sahel region of Africa where feed resources are scarce 8 out of 12 months a year, anything we can do to increase pasture resources and animal productivity while maintaining a healthy ecosystem, could improve the quality of life in the community. / Ph. D.

Die aktuell beobachteten, drastischen Veränderungen in der Arktis, die auch als Effekt der Arktische Verstärkung bekannt sind, sind das Ergebnis eines komplexen Systems regionaler und überregionaler Prozesse und Rückkopplungsmechanismen. Die Komplexität der Wolkenprozesse in einer Region, in der häufig Wolken auftreten, unterstreicht die Notwendigkeit, mehrdeutige Modellierungsergebnisse mit Hilfe von Messungen zu validieren. Insbesondere die atmosphärische Grenzschicht (ABL) und die Erdoberfläche werden durch Strahlungsenergiequellen und -senken in verschiedenen Höhen beeinflusst, weshalb Vertikalmessungen erforderlich sind. Diese Dissertation befasst sich mit der Analyse ballongetragener in-situ Profilmessungen der Strahlung im thermischen Infrarot (TIR), um allgemeine Merkmale der vertikalen Struktur des Strahlungsfeldes der Arktischen Grenzschicht zu identifizieren und zu untersuchen, wie sich die Strahlungsprofile entwickeln und mit den anderen Parametern der Grenzschicht zusammenhängen. In-situ Messungen atmosphärischer Parameter in der arktischen ABL wurden mit dem Fesselballonsystem BELUGA (“Balloon-bornE moduLar Utility for profilinG the lower Atmosphere”) während drei Feldkampagnen durchgeführt: im Sommer 2020 während der “Multidisciplinary drifting Observatory for the Study of Arctic Climate” Expedition (MOSAiC) und im Herbst 2021 und im Frühjahr 2022 in Ny-Ålesund (Svalbard). Die Vertikalprofile der TIR-Bestrahlungsstärke wurden von einer speziell angefertigten, auf Strahlungsmessungen spezialiserten Nutzlast für BELUGA beobachtet, und die Strahlungsheizrate wurde abgeleitet. Die Beobachtungen wurden dann mit einem Strahlungstransportmodell abgeglichen. Die insgesamt 70 ballongetragene Profile wurden anhand des Zustands der Atmosphäre in vier Hauptkategorien eingeteilt: wolkenlos, niedrige flüssig-keitstragende Wolken, hohe flüssigkeitstragende Wolken und hohe Eiswolken. Die mittleren Vertikalrofile für diese Fälle wurden abgeleitet, um die allgemeinen Merkmale der TIR-Strahlungsprofile in der arktischen ABL zu charakterisieren. Fälle mit wolkenloser Atmosphäre sind durch ein stark negatives Oberflächen-TIR-Strahlungsbudget gekennzeichnet, mit einer schwachen, aber ziemlich homogenen Strahlungskühlung von etwa -2 Kday-1 über die gesamte ABL-Säule. Das Vorhandensein von Flüssigwasserwolken verändert die TIR-Nettostrahlungsstärke an der Erdoberfläche erheblich, mit Werten nahe 0 Wm-2. An der Wolkenoberkante zeigen niedrige Flüssigwasserwolken eine starke Abkühlung im TIR, mit Messwerten von bis zu -80 Kday-1. Diese Abkühlung ist für das Fortbestehen einer Wolke von grundlegender Bedeutung, da es die turbulente Durchmischung und den Lufteinschluss fördert. Bei hohen Flüssigwasserwolken findet die Abkühlung der Wolkenoberkante außerhalb der ABL statt. Jedoch gibt es einen Strah-lungseffekt durch diese Wolken, sowohl auf darunter liegende Wolken als auch auf die Erdoberfläche. Hohe Eiswolken zeigen eine schwächere Strahlungskühlung in der ABL, da Eis pro Masseneinheit nicht so effektiv ist wie flüssiges Wasser. Fallstudien wurde betrachtet, die alle BELUGA-Messungen umfassen und die thermodynamischen Bedingungen der ABL während verschiedener Wolkenbedingungen zeigen. Kombinationen von aufeinanderfolgenden Ballonflügen wurden verwendet um die Variation der TIR-Strahlungsprofile bei wechselnden Wolkenbedeckungsgraden zu erforschen und sie teilweise mit der Entwicklung der Thermodynamik von ABL in Verbindung zu bringen. Die Bedeutung bewölkter Luftmassen für den Strahlungshaushalt wurde untersucht, wobei sich zeigte, dass je nach dem absoluten Temperaturunterschied zwischen der Wolkenbasis und der Erdoberfläche eine Strahlungserwärmung (-kühlung) an der Wolkenbasis und eine Strahlungskühlung (-erwärmung) an der Erdoberfläche zu erwarten ist.:Contents 1 Introduction . . . . . . . . . . . . . . . . . . 1 1.1 Clouds in the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Arctic Amplification . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.3 Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.4 Radiative forcing . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 In situ observations of Arctic clouds . . . . . . . . . . . . . . . . . . 4 1.3 Objectives and outline . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Definitions . . . . . . . . . . . . . . . . . . 7 2.1 Atmospheric radiative quantities . . . . . . . . . . . . . . . . . . . . 7 2.2 Cloud microphysical properties . . . . . . . . . . . . . . . . . . . . . 10 2.3 Cloud optical characteristics . . . . . . . . . . . . . . . . . . . . . . 12 3 Instruments, data and methods . . . . . . . . . . . . . . . . . . 15 3.1 Tethered balloon system . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2 Broadband radiation package . . . . . . . . . . . . . . . . . . . . . . 19 3.2.1 Data acquisition and technical validation . . . . . . . . . . . 19 3.2.2 Uncertainty of measurements of irradiance . . . . . . . . . . . 22 3.2.3 Radiative temperature tendency . . . . . . . . . . . . . . . . 23 3.3 Video ice particle sampler . . . . . . . . . . . . . . . . . . . . . . . . 24 3.4 Additional data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.4.1 Surface radiation measurements . . . . . . . . . . . . . . . . . 25 3.4.2 Radiosonde profiles . . . . . . . . . . . . . . . . . . . . . . . 26 3.4.3 Cloud properties . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.5 Radiative transfer simulations . . . . . . . . . . . . . . . . . . . . . 27 3.5.1 Model setup . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.5.2 Temperature and humidity profiles . . . . . . . . . . . . . . . 27 3.5.3 Clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Field campaigns overview . . . . . . . . . . . . . . . . . . 29 4.1 MOSAiC - summer 2020 . . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.1 Site overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.2 Synoptics conditions . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.3 Clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.1.4 Balloon operations and data . . . . . . . . . . . . . . . . . . 35 4.2 Ny-˚Alesund - autumn 2021 . . . . . . . . . . . . . . . . . . . . . . . 36 4.2.1 Site overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 4.2.2 Synoptic conditions and clouds . . . . . . . . . . . . . . . . . 36 4.2.3 Balloon operations and data . . . . . . . . . . . . . . . . . . 39 4.3 Ny-˚Alesund - spring 2022 . . . . . . . . . . . . . . . . . . . . . . . . 40 4.3.1 Synoptic conditions and clouds . . . . . . . . . . . . . . . . . 40 4.3.2 Balloon operations and data . . . . . . . . . . . . . . . . . . 43 5 Statistical evaluation of radiation profiles . . . . . . . . . . . . . . . . . . 45 5.1 Radiative states at the surface . . . . . . . . . . . . . . . . . . . . . 45 5.2 Classification of observed profiles . . . . . . . . . . . . . . . . . . . . 48 5.3 Cloudless cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5.4 Elevated ice clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 5.5 Low-level liquid-bearing clouds . . . . . . . . . . . . . . . . . . . . . 53 5.6 Elevated liquid-bearing clouds . . . . . . . . . . . . . . . . . . . . . 54 6 States and transitions: case studies . . . . . . . . . . . . . . . . . . 57 6.1 Cloudless: 4 April 2022 . . . . . . . . . . . . . . . . . . . . . . . . . 57 6.2 Low-level liquid-bearing cloud: 13 July 2020 . . . . . . . . . . . . . 59 6.3 Dissipation of a low-level cloud: 30 September 2021 . . . . . . . . . 63 6.4 Elevated liquid-bearing cloud: 23 July 2020 . . . . . . . . . . . . . . 65 7 Radiative effect of cloudy air masses . . . . . . . . . . . . . . . . . . 69 7.1 Deriving profiles of cloud radiative effect . . . . . . . . . . . . . . . 69 7.2 Profile modulation by elevated clouds . . . . . . . . . . . . . . . . . 71 7.2.1 Elevated ice cloud . . . . . . . . . . . . . . . . . . . . . . . . 71 7.2.2 Elevated liquid bearing cloud . . . . . . . . . . . . . . . . . . 72 7.3 Clouds in different air masses . . . . . . . . . . . . . . . . . . . . . . 73 7.3.1 Characterization of air mass . . . . . . . . . . . . . . . . . . . 74 7.3.2 Temperature, clouds, and microphysics properties . . . . . . . 75 7.3.3 Net irradiance . . . . . . . . . . . . . . . . . . . . . . . . . . 77 7.3.4 Radiative temperature tendency . . . . . . . . . . . . . . . . 78 8 Summary, conclusions, and outlook . . . . . . . . . . . . . . . . . . 81 Appendix . . . . . . . . . . . . . . . . . . 85 Bibliography . . . . . . . . . . . . . . . . . . 87 List of Abbreviations . . . . . . . . . . . . . . . . . . 105 List of Variables . . . . . . . . . . . . . . . . . . 107 List of Figures . . . . . . . . . . . . . . . . . . 109 List of Tables . . . . . . . . . . . . . . . . . . 111 List of Peer-Reviewed Publications . . . . . . . . . . . . . . . . . . 113 List of Data Publications . . . . . . . . . . . . . . . . . . 115 Acknowledgements . . . . . . . . . . . . . . . . . . 117 / The currently observed drastic changes in the Arctic and known as Arctic amplification are the result of a complex system of local and remote processes and feedback mechanisms. The complexity of cloud processes in a region where clouds are often present underlines the need to constrain ambiguous model results using observations. In particular, the atmospheric boundary layer (ABL) and the surface are affected by radiative energy sources and sinks at various altitudes, therefore measurements in the vertical dimension are needed. This dissertation analyzes in situ balloon-borne profile observations of thermal-infrared (TIR) radiation to identify some general features of the vertical structure of the radiative field of the Arctic ABL and to investigate how radiation profiles evolve and interact with the other ABL quantities. In situ measurements of atmospheric parameters in Arctic ABL were obtained using the tethered-balloon system BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) during three field campaigns: in summer 2020 during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, and in Ny-\AA lesund (Svalbard) in autumn 2021 and in spring 2022. Profiles of TIR irradiance were observed using a custom-made radiation payload, and radiative temperature tendency were derived. Observations were then matched using a radiative transfer model. A total of 70 balloon-borne profiles was sorted into four main categories based on the atmospheric states: cloudless, low-level liquid-bearing cloud, elevated liquid-bearing cloud, and elevated ice cloud. Average profiles for these cases were derived to characterize the general features of TIR radiation profiles in the Arctic ABL. Cloudless atmospheres are characterized by a strongly negative surface TIR radiation budget, with a weak but rather homogeneous radiative cooling of about -2 Kday-1 over the full ABL column. The presence of liquid-bearing clouds significantly modify the surface TIR net irradiance, with values close to 0 Wm-2. At cloud top, low-level liquid-bearing clouds present a strong TIR cooling, with observed values up to -80 Kday-1. This cooling is fundamental in maintaining the cloud, as it promotes turbulent mixing and entrainment. In elevated liquid-bearing clouds the cloud top cooling is located outside the ABL, but the radiative effect of the cloud is still present, impacting both any underlying cloud and the surface. Elevated ice clouds allow a weak radiative cooling in the ABL, as ice is not as effective as liquid water per unit of mass.Case studies were set up including the full suite of BELUGA measurements, and display the ABL thermodynamic conditions under different cloud conditions. Combinations of consecutive balloon flights were used to explore the variation of TIR radiation profiles under changing cloud covers and partially associating them with the evolution of ABL thermodynamics. The radiative importance of cloudy air masses was investigated, showing that depending on the absolute temperature difference between the base of the cloud and the surface, radiative warming (cooling) is expected at cloud base and radiative cooling (warming) is expected at the surface.:Contents 1 Introduction . . . . . . . . . . . . . . . . . . 1 1.1 Clouds in the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Arctic Amplification . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.3 Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.4 Radiative forcing . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 In situ observations of Arctic clouds . . . . . . . . . . . . . . . . . . 4 1.3 Objectives and outline . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Definitions . . . . . . . . . . . . . . . . . . 7 2.1 Atmospheric radiative quantities . . . . . . . . . . . . . . . . . . . . 7 2.2 Cloud microphysical properties . . . . . . . . . . . . . . . . . . . . . 10 2.3 Cloud optical characteristics . . . . . . . . . . . . . . . . . . . . . . 12 3 Instruments, data and methods . . . . . . . . . . . . . . . . . . 15 3.1 Tethered balloon system . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2 Broadband radiation package . . . . . . . . . . . . . . . . . . . . . . 19 3.2.1 Data acquisition and technical validation . . . . . . . . . . . 19 3.2.2 Uncertainty of measurements of irradiance . . . . . . . . . . . 22 3.2.3 Radiative temperature tendency . . . . . . . . . . . . . . . . 23 3.3 Video ice particle sampler . . . . . . . . . . . . . . . . . . . . . . . . 24 3.4 Additional data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.4.1 Surface radiation measurements . . . . . . . . . . . . . . . . . 25 3.4.2 Radiosonde profiles . . . . . . . . . . . . . . . . . . . . . . . 26 3.4.3 Cloud properties . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.5 Radiative transfer simulations . . . . . . . . . . . . . . . . . . . . . 27 3.5.1 Model setup . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.5.2 Temperature and humidity profiles . . . . . . . . . . . . . . . 27 3.5.3 Clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Field campaigns overview . . . . . . . . . . . . . . . . . . 29 4.1 MOSAiC - summer 2020 . . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.1 Site overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.2 Synoptics conditions . . . . . . . . . . . . . . . . . . . . . . . 30 4.1.3 Clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.1.4 Balloon operations and data . . . . . . . . . . . . . . . . . . 35 4.2 Ny-˚Alesund - autumn 2021 . . . . . . . . . . . . . . . . . . . . . . . 36 4.2.1 Site overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 4.2.2 Synoptic conditions and clouds . . . . . . . . . . . . . . . . . 36 4.2.3 Balloon operations and data . . . . . . . . . . . . . . . . . . 39 4.3 Ny-˚Alesund - spring 2022 . . . . . . . . . . . . . . . . . . . . . . . . 40 4.3.1 Synoptic conditions and clouds . . . . . . . . . . . . . . . . . 40 4.3.2 Balloon operations and data . . . . . . . . . . . . . . . . . . 43 5 Statistical evaluation of radiation profiles . . . . . . . . . . . . . . . . . . 45 5.1 Radiative states at the surface . . . . . . . . . . . . . . . . . . . . . 45 5.2 Classification of observed profiles . . . . . . . . . . . . . . . . . . . . 48 5.3 Cloudless cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5.4 Elevated ice clouds . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 5.5 Low-level liquid-bearing clouds . . . . . . . . . . . . . . . . . . . . . 53 5.6 Elevated liquid-bearing clouds . . . . . . . . . . . . . . . . . . . . . 54 6 States and transitions: case studies . . . . . . . . . . . . . . . . . . 57 6.1 Cloudless: 4 April 2022 . . . . . . . . . . . . . . . . . . . . . . . . . 57 6.2 Low-level liquid-bearing cloud: 13 July 2020 . . . . . . . . . . . . . 59 6.3 Dissipation of a low-level cloud: 30 September 2021 . . . . . . . . . 63 6.4 Elevated liquid-bearing cloud: 23 July 2020 . . . . . . . . . . . . . . 65 7 Radiative effect of cloudy air masses . . . . . . . . . . . . . . . . . . 69 7.1 Deriving profiles of cloud radiative effect . . . . . . . . . . . . . . . 69 7.2 Profile modulation by elevated clouds . . . . . . . . . . . . . . . . . 71 7.2.1 Elevated ice cloud . . . . . . . . . . . . . . . . . . . . . . . . 71 7.2.2 Elevated liquid bearing cloud . . . . . . . . . . . . . . . . . . 72 7.3 Clouds in different air masses . . . . . . . . . . . . . . . . . . . . . . 73 7.3.1 Characterization of air mass . . . . . . . . . . . . . . . . . . . 74 7.3.2 Temperature, clouds, and microphysics properties . . . . . . . 75 7.3.3 Net irradiance . . . . . . . . . . . . . . . . . . . . . . . . . . 77 7.3.4 Radiative temperature tendency . . . . . . . . . . . . . . . . 78 8 Summary, conclusions, and outlook . . . . . . . . . . . . . . . . . . 81 Appendix . . . . . . . . . . . . . . . . . . 85 Bibliography . . . . . . . . . . . . . . . . . . 87 List of Abbreviations . . . . . . . . . . . . . . . . . . 105 List of Variables . . . . . . . . . . . . . . . . . . 107 List of Figures . . . . . . . . . . . . . . . . . . 109 List of Tables . . . . . . . . . . . . . . . . . . 111 List of Peer-Reviewed Publications . . . . . . . . . . . . . . . . . . 113 List of Data Publications . . . . . . . . . . . . . . . . . . 115 Acknowledgements . . . . . . . . . . . . . . . . . . 117