Les ions jouent un rôle majeur sur les processus biologiques affectant la molécule d'ADN que ce soit en termes d'activité de liaison de protéines à l'ADN ou d'encapsulation de l'ADN dans les capsides virales ou le noyau. L'activité de protéines sur l'ADN est, par ailleurs, fréquemment liée à une courbure locale de l'axe de la double hélice, que ce soit en raison d'une séquence intrinsèquement courbée, ou, via la capacité de protéines à courber la séquence sur laquelle elles se fixent. Être capable de caractériser et comprendre l'effet des ions présents en solution, de la courbure et de la dénaturation locale de la molécule d'ADN sur les conformations de cette dernière est donc crucial pour approfondir la compréhension de nombreux processus biologiques. Des travaux, tant expérimentaux que théoriques, ont déjà été menés sur ces questions mais celles-ci sont encore largement débattues. En effet, pour y répondre, doivent notamment être développées des méthodes expérimentales qui ne perturbent pas significativement la conformation de l'ADN ou le complexe ADN-protéine, ainsi que des modèles théoriques associés permettant une analyse précise des données expérimentales et leur compréhension physique. L'objectif de ce travail est de proposer des outils expérimentaux et théoriques permettant de décrire physiquement l'influence de défauts locaux présents sur la molécule d'ADN et de paramètres physico-chimiques de la solution environnante. A cette fin, des données expérimentales ont été acquises à l'échelle de la molécule unique grâce à la technique haut-débit de "Tethered Particle Motion" (HT-TPM). Le TPM consiste à enregistrer, au cours du temps, les positions d'une particule accrochée à l'extrémité d'une molécule d'ADN, immobilisée par son autre extrémité sur un support en verre. L'utilisation d'une biopuce permettant la parallélisation des complexes ADN/particule et l'acquisition "à haut débit" de données TPM a permis d'obtenir une grande accumulation de statistiques individuelles. Une procédure d'analyse efficace a été élaborée afin de déterminer les amplitudes du mouvement des assemblages ADN-particules valides. En parallèle, ont été effectuées des simulations basées sur un modèle de physique statistique mésoscopique dans lequel la molécule d'ADN est assimilée à une chaîne de billes de rayons variables dont les déplacements sont régis par la diffusion brownienne et une énergie potentielle d'interaction prenant en compte notamment l'énergie de courbure du polymère ADN. Une première étude a porté sur l'effet de la force ionique de la solution environnante sur la longueur de persistance Lp, qui traduit la rigidité du polymère d'ADN. Les valeurs de Lp extraites des données de HT-TPM ont fait apparaître une décroissance de la longueur de persistance de 55 à 30 nm, corrélée à l'augmentation de la force ionique, avec une décroissance plus forte observée pour les ions divalents Mg2+ que pour les ions monovalents Na+. Les valeurs de Lp déterminées sur une plage étendue de force ionique ont permis de valider l'approche théorique proposée par Manning en 2006 dans la cas Na+. Une deuxième étude a conduit à l'élaboration d'une méthode permettant de quantifier l'angle de courbure locale induite par une séquence spécifique ou la liaison d'une protéine sur la molécule d'ADN. L'échantillon modèle a été obtenu en insérant de une à sept séquences CAAAAAACGG en phase. Une description théorique de la chaîne d'ADN appelée "kinked Worm-Like Chain" a été proposée. Elle conduit à une formule simple de la distance bout-à-bout de l'ADN qui permet d'extraire la valeur de l'angle de courbure à partir des mesures de HT-TPM. Ainsi, il a pu être montré que la séquence CAAAAAACGG induit un angle de 19° ± 4° en accord avec les données de la littérature. Une troisième étude concernant la mesure de l'impact de la dénaturation partielle de l'ADN, induite par la température, sur sa rigidité apparente globale a été menée. Des résultats préliminaires sont proposés. / Ions play an important role in many biological processes affecting the DNA molecule, both for binding activities of DNA-protein interaction, and the DNA packaging in viral capsids or in the cell nucleus. Proteins actions on DNA are also often associated to the double helix curvature, be it because of an intrinsic curved sequence, or of the ability of the proteins, to curve the sequence they are trying to bind. Being able to characterize and understand the effects on the DNA conformation of ions present in solution, DNA local curvature, and local denaturation bubble is essential and crucial for the thorough understanding of many biological processes. Many experimental, and theoretical studies have already been conducted to address these questions. However they remain highly debated. To answer then one must notably develop experimental approaches that minimize alteration of the conformation of the DNA molecule or the complex protein-DNA, as well as associated theoretical models that permit a precise analysis of experimental data as well as their physical understanding. The goal of this work is to develop and propose experimental and theoretical tools which would provide a physical description of the influence of DNA local defects on the DNA molecule as well as of physicochemical conditions of the DNA environmental solution. For this purpose, experimental data have been collected, at a single molecule level, using the High-Throughput Tethered Particle Motion" (HT-TPM) technique. TPM consists of recording the location of a particle grafted by one end of a single DNA molecule and immobilized, at the other end, to a glass surface. The use of a biochip that enables the parallelization of DNA/particle complexes and the ensuing high-throughput data acquisition permitted to obtain a large accumulation of individual statistics. A strong analysis procedure has been developed to extract and quantify the amplitude of motion of the valid DNA/particle complexes . Alongside that, simulations have been run, based on a mesoscopic statistical mechanics model in which the DNA molecule is related to a chain of monomers with varying radius and in which the amplitude of motion is governed by both the Brownian motion and by the interaction potential associated to stretching and bending energies of the polymer. A first study was conducted on the effect of the ionic strength induced by surrounding ions in solution on the DNA persistence length (Lp) which characterizes the DNA polymer rigidity. The extracted Lp values of HT-TPM measurement decrease from 55 to 30 nm when the ionic strength increases. A stronger decrease was observed in presence of divalent ions Mg2+ than with monovalent ions Na+. This quantification of Lp dependence, on a large and strongly prospected range of ionic strengthes, tends to validate the theoretical approach proposed in 2006 by Manning in presence of monovalent ions Na+. A second project allows us to develop a method of evaluation and quantification of local DNA bending angles, induced either by specific intrinsic sequence, or by the binding of proteins on DNA. Constructs made of 575 base-pair DNAs with in-phase assemblies of one to seven sequences CAAAAAACGG was used. A theoretical description of the polymer chain, named "kinked Worm-Like Chain" was proposed which leads to a simple formulation of the end-to-end distance of DNA molecules allowing to extract local bend angles from HT-TPM measurement. As a result, we find that the sequence CAAAAAACGG induces a bend angle of 19° ± 4° in agreement with other value from the literature. A third study concerning the influence of temperature-induced partial denaturation on the global apparent rigidity parameters of the polymer was conducted. Preliminary results are proposed.

Aim  The purposes of this study were to investigate if the load-velocity (L-V) profile parameters – force capacity and efficiency - differ between swimmers of different performance level, and to investigate if efficiency is the key performance indicator between international elite and national elite level swimmers.  Method  Fifty-four swimmers (27 female and 27 male) of either regional level, national elite or international elite level, participated in this study. The swimmers performed three 25 m semi- tethered maximum effort swims with ascending loads (1 kg, 5% and 10% of body mass). Mean velocity during three stroke cycles mid-effort was calculated and plotted as a function of the external added load. A linear regression was established, expressing the relationship between load and velocity, with the intercepts between the axes and the regression line being defined as the theoretical maximum velocity (V0) and load (force capacity, L0). The slope of the regression line (slopeLV) serves as an index of efficiency. Results A statistically significant difference was found between the three performance levels for all L- V profile variables for front crawl: V0 (F [2, 51] = 7.76, p<0.001), L0 (F [2, 51] = 5.18, p=0.009), and slopeLV (F [2, 51] = 3.36, p=0.043). A paired t-test revealed no difference in slopeLV between matched international elite and national elite level swimmers (t [9] = 1.42, p=0.188), but a near significant difference in L0 (t [9] = 2.11, p=0.064) . Both slopeLV and L0 for front crawl had a strong correlation with personal best in 100 m front crawl (PB100). Conclusion Efficiency was not found to be the key performance indicator between matched international elite and national elite swimmers in this study, and neither was force capacity. Nevertheless, a significant difference in all front crawl L-V profile parameters was found between performance level groups, but post hoc analyses indicated no difference between adjacent performance levels neither in L0 nor slopeLV. There was however a strong correlation between both slopeLV, and L0, to the swimmers’ PB100. All these findings imply that efficiency and force capacity seem to be of equal importance for high performance, but swimmers use different strategies to reach the high swim velocity. / Longitudinal development of performance determining factors in swimming (NIH)

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Aerostats and Stratolites could play a major role in expanding current satellite and other technologies in the near future. A study was made on the development of aerostat platforms and the current state of Stratolite development. The aim was to develop an airship system that is capable of maintaining a specific position regardless of the presence of wind. The various applications of such a geostationary platform are discussed. A dynamic model of an airship was developed and a simulation was implemented in software. This was done to study the possibility of developing aerostats like these. A tethered airship system was developed and built to demonstrate that it is possible to control the position of an airship. The airship system uses current technology in an unique combination to fulfil the requirement of remaining stationary despite the influence of wind. Various control system design techniques were used to implement the controllers. Linear models of the airship system were identified practically and used to design the controllers. The controllers were tested in simulation as well as practically and the results of these tests are given. It was concluded that there exists potential for the development of Stratolite systems, although there exists a fair amount of challenges and obstacles that would need to be overcome before this technology could be implemented. / AFRIKAANSE OPSOMMING: Aerostats en Stratolites kan ’n besondere rol speel in die uitbreiding van huidige sateliet- en ander aardwaarnemingstoepassings. ’n Studie is gemaak oor die ontwikkeling van Aerostat platforms en die huidige stand van Stratolite ontwikkeling. Die mikpunt was om ’n lugskipstelsel te ontwikkel wat in staat is om ’n spesifieke posisie te handhaaf ten spyte van die invloed van wind. Die verskeidenheid van toepassings, waarvoor so ’n geostasionêre platform gebruik kan word, word genoem. ’n Dinamiese model van ’n lugskip is ontwikkel en die stelsel is in sagteware gesimuleer. Dit is gedoen om die moontlikheid te ondersoek om sulke Aerostats in die toekoms te ontwikkel. ’n Lugskipstelsel, wat aan die grond geanker word met ’n kabel, is ontwerp en gebou. Die stelsel is gedemonstreer en daar is bewys dat dit moontlik is om die posisie van die lugskip te beheer. Die lugskip gebruik huidige tegnologie wat in ’n unieke kombinasie saamgevoeg is om te illustreer dat dit moontlik is vir die lugskip om stasionêr te bly ten spyte van wind. Verskeie beheerstelsels ontwerptegnieke is gebruik om die beheerders mee te implementeer. Lineêre modelle van die lugskip is prakties geïdentifiseer en is gebruik om die beheerders te ontwerp. Die lugskip se beheerders is in simulasie sowel as prakties getoets en die resultate van hierdie toetse word gegee. Die projek bevestig dat daar ’n potensiaal bestaan vir die praktiese ontwikkeling van Stratolite stelsels. Daar is egter ’n hele paar uitdagings en probleme wat eers uit die weg geruim sal moet word, voordat hierdie tegnologie ’n alledaagse werklikheid sal word.

Submitted by GABRIEL MOTTA PINHEIRO BRISOLA null (gabriel-brisola@hotmail.com) on 2016-11-18T17:48:43Z No. of bitstreams: 1 DISSERTAÇÃO ÚLTIMA VERSÃO.pdf: 3813641 bytes, checksum: c61ebbd4c02dd51b7b1ae87320fcf1d5 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-24T15:09:44Z (GMT) No. of bitstreams: 1 brisola_gmp_me_rcla.pdf: 3813641 bytes, checksum: c61ebbd4c02dd51b7b1ae87320fcf1d5 (MD5) / Made available in DSpace on 2016-11-24T15:09:44Z (GMT). No. of bitstreams: 1 brisola_gmp_me_rcla.pdf: 3813641 bytes, checksum: c61ebbd4c02dd51b7b1ae87320fcf1d5 (MD5) Previous issue date: 2016-09-29 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo geral do presente trabalho foi verificar o potencial ergogênico da suplementação por 4 semanas de β-alanina sobre a potência anaeróbia, habilidade de esforços repetidos e desempenho no polo aquático. 22 jogadores de elite do sexo masculino (média±dp: idade = 18±4 anos, peso = 78,5±9,5 kg e altura = 1,79±0,06 m) participaram do estudo, que foi conduzido de modo randomizado, duplo cego e placebo controlado. Os participantes foram divididos em dois grupos (β-alanina e placebo) de 11 atletas cada e foram submetidos a testes específicos (teste de habilidade de esforços repetidos (RSA) e teste máximo de 30s de salto sob o gol (30CJ)) e semi-específicos (teste de 30s máximo em nado atado (30ATADO), teste máximo de 3 minutos (All Out 3min), teste incremental máximo (GXTATADO) e performance de 200m em nado crawl (P200m)) para a modalidade e um jogo simulado para possibilitar o rastreamento das atividades realizadas por meio de filmagem. As avaliações ocorreram pré e após o período de suplementação (4 semanas). Não foram encontrados efeitos significativos de interação entre os grupos para nenhuma variável do presente estudo. No entanto, alguns ligeiros indícios de melhora com a suplementação de β-alanina foram encontrados como: (1) melhora significativa entre os momentos (pré × pós) no número total de sprints durante o jogo simulado de polo aquático; (2) efeito provavelmente benéfico (análise de inferência baseada na magnitude) para o tempo médio, pior tempo e tempo total na primeira série do teste de RSA (RSA1); (3) melhora significativa entre os momentos na força média e integral de força durante o teste 30ATADO e na P200m; (4) melhora significativa entre os momentos na força pico no teste GXTATADO. Portanto, conclui-se que a suplementação por 4 semanas de β-alanina pode promover apenas melhorar ligeiramente alguns parâmetros relacionados a habilidade de nado no polo aquático como número total de sprints em jogo simulado, tempo médio, pior tempo e tempo total no teste de RSA, força média e integral de força no 30ATADO, P200m e força crítica no GXTATADO. / The overall aim of this study was to investigate the ergogenic effect of 4 weeks β-alanine supplementation on the anaerobic power, ability to performed repeated efforts and performance of water polo. 22 male elite players (mean±SD age = 18±4 years, weight = 78.5±9.5 kg and height = 1.79±0.06 m) participated in the study, which was conducted in order randomized, double blind and placebo controlled. Participants were divided into two groups (β-alanine and placebo) of 11 athletes each and were subjected to specific tests (repeated sprint ability test (RSA) and maximum 30s jump under the goal test (30CJ)) and semi-specific (30s maximal test in tethered swimming (30TS), maximal 3 min effort (AllOut-3min), tethered swimming graded exercise test (GXTTS) and 200m in front crawl (P200m)) for the modality and a simulated game to enable tracking of the activities carried out by video record. Assessments occurred before and after the supplementation period (4 weeks). There were no significant interaction effects between the groups for any variable of this study. However, some slight improvement indications with β-alanine supplementation were found to: (1) significant improvement between moments (pre × post) the total number of sprints during the simulated game water polo; (2) probably beneficial effect (magnitude-based inference analysis) for the mean time, worst time and total time in the first series of the RSA test (RSA1); (3) significant improvement between moments for mean force and integral of force during the 30TS and P200m; (4) significant improvement between moments for peak power at GXTTS. Therefore, it is concluded that supplementation for 4 weeks of β-alanine can promote only slightly improve some parameters related to swimming ability in water polo as total number of sprints in simulated game, mean time, worst time and total time on test RSA, mean and integral of force in 30TS, P200m and critical force in GXTTS. / FAPESP: 2014/02186-7

Orientador: Benedito Sérgio Denadai / Banca: Cassiano Merussi Neiva / Banca: Fabrizio Caputo / Banca: Emerson Franchin / Banca: Mauro Gonçalves / Resumo: Não se tem observado a preocupação com a descrição dos domínios de intensidade na natação e poucas tentativas foram realizadas para ajustar o modelo de P-tLim às condições desta modalidade de exercício. Este estudo pretendeu ajustar o modelo P-tLim à natação com o recurso do controle de cargas possibilitado pelo nado em condição atada. Assim como, seu significado fisiológico para a descrição dos domínios pesado/severo obtido pelas relações a serem estabelecidas com a velocidade crítica (VC - limite superior do domínio pesado), com a máxima fase estável do lactato (MFEL, que disputa com VC a indexação do limite superior do domínio pesado) e com a caracterização dos domínios pesado e severo pelos parâmetros de cinética e amplitude do VO2. Em um primeiro estudo, 24 nadadores (16,5 ± 2,7 anos e 67,7 ± 13,5 kg) submeteram-se à estimativa da força de arrasto (Fr = A  v2). A Fr encontrada em máxima velocidade foi fracionada para compor quatro estágios de teste, com tempos de exaustão entre 3-20 min. em crawl-atado. A VC foi estimada empregando quatro distâncias entre 200-1500m. A potência crítica atada (PCAtada) linear (81,9W) e não linear (71,1W) não se diferenciaram (  0,05) dos valores de PC linear (108,2W) e não linear (96,3W) estimados por VC linear (1,2m.s-1) e não linear (1,14m.s-1), através da equação do desempenho. Neste primeiro estudo, pode-se concluir que PCAtada é correlata a VC, podendo representar a capacidade aeróbia. No segundo estudo, dez nadadores (16,6  1,4 anos e 69,8  9,5 kg) foram submetidos às estimativas de PCAtado (equações lineares e hiperbólica de 2-parâmetros), VC (ajuste linear do tempo pela velocidade nos desempenhos de 200, 400 e 800m), PAtadaMFEL (3 ou 4 esforços entre 95 a 105% da carga em PCAtada hiperbólica) e à vMFEL (3 ou 4 esforços entre 85 a 95% do velocidade máxima do crawl nos 400m)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: There is a lack of studies describing the domains of intensity in swimming, and few works approaches the P-tLim model in swimming. This study provided a way to assess the P-tLim model in swimming, applying the load controlled environment in full-tethered condition. The physiological meaning for the description of heavy and severe domains was established from the relationships of critical velocity (CV - upper boundary of heavy domain) to maximal lactate steady state (MLSS, conflicting with VC to demarcate the upper boundary of heavy domain), and from the descriptive characterization of kinetic and amplitude parameters of VO2. In he first study, 24 swimmers with 16.5 ± 2.7 years and 67.7 ± 13.5 kg were undertaken to drag force (Fr) estimation (Fr = A  v2). The Fr at maximal crawl velocity was the load that was fractioned to build the sets, lasting 3-20min until exhaustion. CV was calculated from distance between 200-1500m. The linear (81.9W) and non-linear (71.1W) PTethCrit were not different (  0.05) from the values of linear (108.2W) and non-linear (96.3W) PC estimative obtained from linear (1.2m.s-1) and non-linear (1.14m.s-1) CV through swim performance equation. It was conclude that PCTeth was related to CV, and reliable to indexes aerobic capacity. The second work, did analyze ten male swimmers (16.6  1.4 years and 69.8  9.5kg) that were submitted to the measurements of the CPTeth (linear and non-linear two parameters equation), CV (linear adjustment between time and velocity performance in the 200, 400 and 800m), PTethMLSS (3 or 4 trials ranging from 95 to 105% of the load at non-linear PCAtada), and vMLSS (3 or 4 trials ranging from 85 to 95% of the 400-m crawl performance). The results shown that neither CV (1.19  0.12m.s-1) nor the CPTeth (99.4  23.0W) matches the statements for MLSS, once differences were observed to the vMLSS (1.17  0.11m.s-1)... (Complete abstract click electronic access below) / Doutor

Orientador: Claudio Alexandre Gobatto / Banca: Eliete Luciano / Banca: René Brenzikofer / Resumo: No modelo de natação para ratos, a associação das intensidades de exercício determinadas por meio da lactacidemia com as suas respectivas sobrecargas são passíveis de crítica, uma vez que a quantificação dos pesos atados ao animal pode não representar efetivamente o esforço real do animal para sua manutenção na superfície da água, devido a esta metodologia sofrer influência da densidade corporal e dos padrões de nado apresentados pelos animais. O principal objetivo desse estudo foi desenvolver um modelo de natação atada para roedores o qual permitiu a determinação direta e em tempo real da força de nado realizada pelo animal e verificar a possível existência de diferentes padrões de nado. Além disso, foi feita a discriminação da densidade corporal em animais controles e induzidos à obesidade, com intuito de destacar consistentemente a influência da flutuabilidade na natação. Foram utilizados 24 rattus norvegicus albinus, machos, com 150 dias de idade, divididos em animais controles e induzidos à obesidade por meio da redução de ninhada somada a uma dieta hiperlipídica. Os animais tiveram a densidade corporal determinada por meio de um aparato de pesagem hidrostática utilizando um sistema de aquisição de dados. Posteriormente todos os ratos foram avaliados no teste de máxima fase estável de lactato adaptado para natação atada. Por meio do modelo experimental de indução a obesidade, foi possível induzir aumento significativo do peso e volume corporal, alem da redução da densidade corporal dos animais no grupo obeso. As avaliações de animais controles e obesos revelaram a influência significativa da densidade corporal na determinação das intensidades de exercício, principalmente quando as cargas foram expressas em valores absolutos. Estudos que fazem uso do modelo de natação para ratos, principalmente de caráter longitudinal... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the swimming model for rats, the association between the blood lactate concentration with the exercise intensity could be criticized once the workload quantification could not represent effectively the effort performed by the rat to keep himself on the surface, due to it be affected by the body density and the swimming patterns present by the animals. Thus, the mainly objective of this study was develop a apparatus for tethered swimming for rats, that allows the monitoring of swimming force during all exercise time and to verify the existence of different sorts of swimming patterns. 24 male rattus novergicus albinus, with 150 days of age were used, divided in control and obese induced animals by a nest reduction and hyper-lipid diet. All animals had their body density determined by hydrostatic weighing with an acquiring data device. Later the animals were evaluated in maximal lactate steady state test adapted to the tethered swimming. Was possible to induce significant weight and body volume increase in the obese group beside the reduction of the body density. The assessment of control and obese animals reveled significant body density influence in the workload determination, mainly when the workload was expressed in absolute values. Tethered swimming model allowed the investigation of statistic parameters of the data signal, which showed that the signal amplitude varied in function of the intensity, however the dispersion did not. Also the visual analyses of the force kinetic allowed the identification of 4 swimming patterns and the speculation about the reason and consequences of it incidence. Therefore animals that present such swimming patterns which can influence the assessment should be removed from the sample. Studies that make use of the swimming model for rats, mainly those of longitudinal duration or that make use of interventions that may change the animal's body composition...(Complete abstract click electronic access below) / Mestre

Perceiving and responding to the environment is key to survival. Using the prokaryotic equivalent of a nervous system – the chemotaxis system – bacteria sense chemical stimuli and respond by adjusting their movement accordingly. In chemotactic bacteria, such as the well-studied E. coli, environmental nutrient sensing is achieved through a membrane embedded protein array that specifically clusters at the cell poles. Signalling to the motor is performed by activation of the CheA kinase, which phosphorylates CheY and CheB. CheY-P tunes the activity of the flagellar motor while CheB-P, together with CheR is involved in adaptation to the stimulus. In E. coli, a dedicated phosphatase terminates the signal. Most bacterial species however, have a much more complex chemotaxis network. Rhodobacter sphaeroides, a model organism for complex chemotaxis systems, has one membrane-embedded chemosensory array and one cytoplasmic chemosensory array, plus several homologs of the E. coli chemotaxis proteins. Signals from both arrays are integrated to control the rotation of a single start-stop flagellar motor. The phosphorelay network has been studied extensively through in vitro phosphotransfer while in vivo studies have established the components of each array and the requirements for formation. Mathematical modelling has also contributed towards inferring connectivities within the signalling network. Starting by constructing a two-hybrid-based interaction network focused on the components of the cytoplasmic chemosensory array, this thesis further addresses its associated adaptation network through a series of in vivo techniques. The swimming behaviour of series of deletion mutants involving the adaptation network of R. sphaeroides is characterised under steady state conditions as well as upon chemotactic stimulation. New connectivities within the R. sphaeroides chemotaxis network are inferred from analysing these data together with results from in vivo photoactivation localisation microscopy of CheB₂. The experimental results are used to propose a new model for chemotaxis in R. sphaeroides.

Made available in DSpace on 2014-06-11T19:30:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-13Bitstream added on 2014-06-13T19:00:57Z : No. of bitstreams: 1 pessoafilho_dm_dr_rcla.pdf: 1143306 bytes, checksum: b016fc73fb992fb299381a40997bc60e (MD5) / Não se tem observado a preocupação com a descrição dos domínios de intensidade na natação e poucas tentativas foram realizadas para ajustar o modelo de P-tLim às condições desta modalidade de exercício. Este estudo pretendeu ajustar o modelo P-tLim à natação com o recurso do controle de cargas possibilitado pelo nado em condição atada. Assim como, seu significado fisiológico para a descrição dos domínios pesado/severo obtido pelas relações a serem estabelecidas com a velocidade crítica (VC - limite superior do domínio pesado), com a máxima fase estável do lactato (MFEL, que disputa com VC a indexação do limite superior do domínio pesado) e com a caracterização dos domínios pesado e severo pelos parâmetros de cinética e amplitude do VO2. Em um primeiro estudo, 24 nadadores (16,5 ± 2,7 anos e 67,7 ± 13,5 kg) submeteram-se à estimativa da força de arrasto (Fr = A  v2). A Fr encontrada em máxima velocidade foi fracionada para compor quatro estágios de teste, com tempos de exaustão entre 3-20 min. em crawl-atado. A VC foi estimada empregando quatro distâncias entre 200-1500m. A potência crítica atada (PCAtada) linear (81,9W) e não linear (71,1W) não se diferenciaram (  0,05) dos valores de PC linear (108,2W) e não linear (96,3W) estimados por VC linear (1,2m.s-1) e não linear (1,14m.s-1), através da equação do desempenho. Neste primeiro estudo, pode-se concluir que PCAtada é correlata a VC, podendo representar a capacidade aeróbia. No segundo estudo, dez nadadores (16,6  1,4 anos e 69,8  9,5 kg) foram submetidos às estimativas de PCAtado (equações lineares e hiperbólica de 2-parâmetros), VC (ajuste linear do tempo pela velocidade nos desempenhos de 200, 400 e 800m), PAtadaMFEL (3 ou 4 esforços entre 95 a 105% da carga em PCAtada hiperbólica) e à vMFEL (3 ou 4 esforços entre 85 a 95% do velocidade máxima do crawl nos 400m)... / There is a lack of studies describing the domains of intensity in swimming, and few works approaches the P-tLim model in swimming. This study provided a way to assess the P-tLim model in swimming, applying the load controlled environment in full-tethered condition. The physiological meaning for the description of heavy and severe domains was established from the relationships of critical velocity (CV - upper boundary of heavy domain) to maximal lactate steady state (MLSS, conflicting with VC to demarcate the upper boundary of heavy domain), and from the descriptive characterization of kinetic and amplitude parameters of VO2. In he first study, 24 swimmers with 16.5 ± 2.7 years and 67.7 ± 13.5 kg were undertaken to drag force (Fr) estimation (Fr = A  v2). The Fr at maximal crawl velocity was the load that was fractioned to build the sets, lasting 3-20min until exhaustion. CV was calculated from distance between 200-1500m. The linear (81.9W) and non-linear (71.1W) PTethCrit were not different (  0.05) from the values of linear (108.2W) and non-linear (96.3W) PC estimative obtained from linear (1.2m.s-1) and non-linear (1.14m.s-1) CV through swim performance equation. It was conclude that PCTeth was related to CV, and reliable to indexes aerobic capacity. The second work, did analyze ten male swimmers (16.6  1.4 years and 69.8  9.5kg) that were submitted to the measurements of the CPTeth (linear and non-linear two parameters equation), CV (linear adjustment between time and velocity performance in the 200, 400 and 800m), PTethMLSS (3 or 4 trials ranging from 95 to 105% of the load at non-linear PCAtada), and vMLSS (3 or 4 trials ranging from 85 to 95% of the 400-m crawl performance). The results shown that neither CV (1.19  0.12m.s-1) nor the CPTeth (99.4  23.0W) matches the statements for MLSS, once differences were observed to the vMLSS (1.17  0.11m.s-1)... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:22:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-31Bitstream added on 2014-06-13T18:49:50Z : No. of bitstreams: 1 reis_igm_me_rcla.pdf: 1760261 bytes, checksum: dec7c3739e75a3afb0a688fcc68236aa (MD5) / No modelo de natação para ratos, a associação das intensidades de exercício determinadas por meio da lactacidemia com as suas respectivas sobrecargas são passíveis de crítica, uma vez que a quantificação dos pesos atados ao animal pode não representar efetivamente o esforço real do animal para sua manutenção na superfície da água, devido a esta metodologia sofrer influência da densidade corporal e dos padrões de nado apresentados pelos animais. O principal objetivo desse estudo foi desenvolver um modelo de natação atada para roedores o qual permitiu a determinação direta e em tempo real da força de nado realizada pelo animal e verificar a possível existência de diferentes padrões de nado. Além disso, foi feita a discriminação da densidade corporal em animais controles e induzidos à obesidade, com intuito de destacar consistentemente a influência da flutuabilidade na natação. Foram utilizados 24 rattus norvegicus albinus, machos, com 150 dias de idade, divididos em animais controles e induzidos à obesidade por meio da redução de ninhada somada a uma dieta hiperlipídica. Os animais tiveram a densidade corporal determinada por meio de um aparato de pesagem hidrostática utilizando um sistema de aquisição de dados. Posteriormente todos os ratos foram avaliados no teste de máxima fase estável de lactato adaptado para natação atada. Por meio do modelo experimental de indução a obesidade, foi possível induzir aumento significativo do peso e volume corporal, alem da redução da densidade corporal dos animais no grupo obeso. As avaliações de animais controles e obesos revelaram a influência significativa da densidade corporal na determinação das intensidades de exercício, principalmente quando as cargas foram expressas em valores absolutos. Estudos que fazem uso do modelo de natação para ratos, principalmente de caráter longitudinal... / In the swimming model for rats, the association between the blood lactate concentration with the exercise intensity could be criticized once the workload quantification could not represent effectively the effort performed by the rat to keep himself on the surface, due to it be affected by the body density and the swimming patterns present by the animals. Thus, the mainly objective of this study was develop a apparatus for tethered swimming for rats, that allows the monitoring of swimming force during all exercise time and to verify the existence of different sorts of swimming patterns. 24 male rattus novergicus albinus, with 150 days of age were used, divided in control and obese induced animals by a nest reduction and hyper-lipid diet. All animals had their body density determined by hydrostatic weighing with an acquiring data device. Later the animals were evaluated in maximal lactate steady state test adapted to the tethered swimming. Was possible to induce significant weight and body volume increase in the obese group beside the reduction of the body density. The assessment of control and obese animals reveled significant body density influence in the workload determination, mainly when the workload was expressed in absolute values. Tethered swimming model allowed the investigation of statistic parameters of the data signal, which showed that the signal amplitude varied in function of the intensity, however the dispersion did not. Also the visual analyses of the force kinetic allowed the identification of 4 swimming patterns and the speculation about the reason and consequences of it incidence. Therefore animals that present such swimming patterns which can influence the assessment should be removed from the sample. Studies that make use of the swimming model for rats, mainly those of longitudinal duration or that make use of interventions that may change the animal’s body composition...(Complete abstract click electronic access below)

Les bicouches lipidiques constituent l’architecture socle des membranes biologiques et l’environnement bidimensionnel de leurs protéines. Ancrées sur une interface hydrophile hydratée, ces systèmes conservent leur fluidité et sont localisés durablement près d’un substrat. Dans ce domaine, nous avons développé une stratégie de fonctionnalisation rapide, peu coûteuse et versatile, permettant la formation d’une membrane biomimétique fluide, ancrée sur des substrats conducteurs spécifiquement conçus pour son étude structurale et dynamique. La chimie de surface proposée forme une liaison covalente forte entre le substrat et des molécules commerciales amphiphiles (Brij, etc), utilisées comme système ancre-harpon. L’extrémité hydrophile (coté ancre) possédant un alcool primaire peu réactif est engagée sur une première couche organique par substitution nucléophile. L’autre extrémité hydrophobe (l’harpon) peut s’insérer dans la membrane et la stabiliser. Un mélange adapté, de ces molécules ancre-harpon avec d’autres purement hydrophiles (PEG, etc), apporte l’hydratation et la densité d’ancres nécessaire à l’interface pour maintenir la membrane éloignée du substrat, permettant ainsi l’intégration de protéines et le transport ionique à travers la membrane. Grâce au support conducteur, la dynamique des ions face aux membranes peut être étudiée par spectroscopie d’impédance électrochimique. Sa faible rugosité et semi-transparence permettent aussi l’utilisation de nombreuses autres techniques dont les microscopies optiques, exaltées ou de fluorescence. Localisées sur une électrode, ces bicouches ancrées s’ouvrent également aux applications biotechnologiques. / Lipid bilayers are the structural backbone of biological membranes and provide a two-dimensional environment for proteins. Tethered on a hydrophilic substrate, these biomimetic models are fluid, long-term stable and localized. In this regard, we propose a direct, cheap and versatile strategy of surface functionalization to tether membranes on a substrate adapted to their structural and dynamics study. The process is based on the functionalization of any flat metal thin film by the covalent binding of commercial surfactant molecules (Brij, …) as “anchor-harpoons”-like systems. Most of these molecules possess unresponsive –OH terminated groups on their hydrophilic moiety (anchor) that can bind a first organic layer by nucleophilic substitution. The opposite hydrophobic tail (harpoon) of the molecule can insert into the membrane and make it stable. An ideal mixing ratio of anchor-harpoons molecules with purely hydrophilic ones (PEG, …), provides the required hydration and density of anchors to the interface for tethering fluid membranes away from the substrate. A few nanometers distance enable ionic flows through the membrane and protein inclusion. The substrate conductivity enables studying ion dynamics facing the membrane by means of electrochemical impedance spectroscopy. Flatness and semi-transparency of the conductor opens the route to many other techniques’ including exalted light microscopy or fluorescence. Localized on electrodes, tethered bilayers further provide a biomimetic model and a support for biotechnology applications.