Identificação de sistemas para o estudo de controle motor.

Qualquer tarefa motora ativa se dá pela ativação de uma população de unidades motoras. Porém, devido a diversas dificuldades, tanto técnicas quanto éticas, não é possível medir a entrada sináptica dos motoneurônios em humanos. Por essas razões, o uso de modelos computacionais realistas de um núcleo de motoneurônios e as suas respectivas fibras musculares tem um importante papel no estudo do controle humano dos músculos. Entretanto, tais modelos são complexos e uma análise matemática é difícil. Neste texto é apresentada uma abordagem baseada em identificação de sistemas de um modelo realista de um núcleo de unidades motoras, com o objetivo de obter um modelo mais simples capaz de representar a transdução das entradas do núcleo de unidades motoras na força do músculo associado ao núcleo. A identificação de sistemas foi baseada em um algoritmo de mínimos quadrados ortogonal para achar um modelo NARMAX, sendo que a entrada considerada foi a condutância sináptica excitatória dendrítica total dos motoneurônios e a saída foi a força dos músculos produzida pelo núcleo de unidades motoras. O modelo identificado reproduziu o comportamento médio da saída do modelo computacional realista, mesmo para pares de sinal de entrada-saída não usados durante o processo de identificação do modelo, como sinais de força muscular modulados senoidalmente. Funções de resposta em frequência generalizada do núcleo de motoneurônios foram obtidas do modelo NARMAX, e levaram a que se inferisse que oscilações corticais na banda-beta (20 Hz) podem influenciar no controle da geração de força pela medula espinhal, comportamento do núcleo de motoneurônios até então desconhecido.

Modulação autonômica cardíaca na distrofia muscular de Duchenne durante tarefa no computador

Introdução: A Distrofia Muscular de Duchenne (DMD) é caracterizada como uma fraqueza muscular progressiva que leva à incapacidade. Devido às dificuldades funcionais enfrentadas pelos indivíduos com DMD, o uso da tecnologia assistiva é essencial para proporcionar ou promover habilidades funcionais. Na DMD, além do comprometimento musculoesquelético, uma disfunção autonômica cardíaca também tem sido relatada. Assim, visamos investigar as respostas autonômicas agudas de indivíduos com DMD durante a realização de uma tarefa no computador. Método: A variabilidade da frequência cardíaca foi avaliada através de métodos lineares e não lineares, utilizando uma cinta torácica com equipamento de monitoramento de eletrocardiograma (ECG). Assim, 45 indivíduos foram incluídos no grupo com DMD e 45 no grupo de desenvolvimento típico (controle), avaliados for 20 minutos em repouso sentado e 5 minutos com a realização de uma tarefa no computador. Resultados: Os indivíduos com DMD apresentaram menor modulação cardíaca parassimpática durante o repouso, que diminuiu ainda mais durante a tarefa no computador. Conclusão: Indivíduos com DMD exibiram respostas autonômicas cardíacas mais intensas durante a tarefa no computador

Responsividade do domínio subir e descer escada da escala de avaliação funcional para pessoas com distrofia muscular de Duchenne, no período de um ano

Objetivo: Determinar a responsividade do domínio subir e descer escada da escala de avaliação funcional em distrofia muscular de Duchenne (DMD), no período de um ano. Método: Participaram do estudo 26 pacientes com DMD. A análise utilizou o Tamanho do Efeito (ES) e a Média Padronizada de Resposta (SRM). Resultados: Atividade de subir escada: o ES mostrou responsividade baixa nos intervalos de avaliação de 3 meses (0,26; 0,35; 0,13; 0,17), baixa a moderada em 6 meses (0,58, 0,48; 0,33), moderada em 9 meses (0,70; 0,68) e alta em 1 ano (0,88). A análise com SRM mostrou responsividade baixa nos intervalos de avaliação de 3 meses (0,29; 0,38; 0,18 e 0,19), baixa a moderada em intervalos de 6 meses (0,59 e 0,51, 0,36), moderada em 9 meses (0,74 e 0,70) e alta em 1 ano (0,89). Atividade de descer escada: O ES apresentou responsividade baixa nos intervalos de avaliação de 3 meses (0,16; 0,25; 0,09; 0,08) e 6 meses (0,48; 0,35; 0,18), baixa a moderada em 9 meses (0,59, 0,44) e moderada em 1 ano (0,71). Análise com SRM mostrou responsividade baixa nos intervalos de 3 meses (0,25; 0,35; 0,12 e 0,09) e 6 meses (0,47; 0,38 e 0,21), moderada a baixa em 9 meses (0,62, 0,49) e moderada em 1 ano (0,74). Conclusão: A avaliação da atividade de subir escada, por meio da FES-DMD-D3, deve ser realizada em intervalos a partir de 9 meses, pois a responsividade é de moderada a alta. A avaliação do descer escadas deve ser realizada anualmente, pois houve responsividade moderada somente a partir de 12 meses

Self-sensing properties of alkali activated blast furnace slag (BFS) composites reinforced with carbon fibers

In recent years, several researchers have shown the good performance of alkali activated slag cement and concretes. Besides their good mechanical properties and durability, this type of cement is a good alternative to Portland cements if sustainability is considered. Moreover, multifunctional cement composites have been developed in the last decades for their functional applications (self-sensing, EMI shielding, self-heating, etc.). In this study, the strain and damage sensing possible application of carbon fiber reinforced alkali activated slag pastes has been evaluated. Cement pastes with 0, 0.29 and 0.58 vol % carbon fiber addition were prepared. Both carbon fiber dosages showed sensing properties. For strain sensing, function gage factors of up to 661 were calculated for compressive cycles. Furthermore, all composites with carbon fibers suffered a sudden increase in their resistivity when internal damages began, prior to any external signal of damage. Hence, this material may be suitable as strain or damage sensor.

Biodiesel production by acid catalysis with heteropolyacids supported on activated carbon fibers

Different catalysts, based on heteropolyacids supported on activated carbon fibers, have been prepared for palmitic acid esterification reaction. The influence of the catalyst (heteropolyacid) and the support on the catalytic activity have been analyzed. The results prove that an adequate combination of both is required to achieve the most suitable catalysts. Regarding to the heteropolyacid, phosphomolybdic acid seems to be the most suitable appropriate taking into account its lowest leaching. About the support, it must show an optimum microporosity, which must be wide enough to allow the entrance and exit of the reagents and products but not too wide in order to avoid the leaching of the catalyst. In addition, both decreasing of the catalytic activity and its recovery over several cycles have been analyzed.

Nanoarchitectures Based on Layered Titanosilicates Supported on Glass Fibers: Application to Hydrogen Storage

This work reports on the synthesis of nanosheets of layered titanosilicate JDF-L1 supported on commercial E-type glass fibers with the aim of developing novel nanoarchitectures useful as robust and easy to handle hydrogen adsorbents. The preparation of those materials is carried out by hydrothermal reaction from the corresponding gel precursor in the presence of the glass support. Because of the basic character of the synthesis media, silica from the silicate-based glass fibers can be involved in the reaction, cementing its associated titanosilicate and giving rise to strong linkages on the support with the result of very stable heterostructures. The nanoarchitectures built up by this approach promote the growth and disposition of the titanosilicate nanosheets as a house-of-cards radially distributed around the fiber axis. Such an open arrangement represents suitable geometry for potential uses in adsorption and catalytic applications where the active surface has to be available. The content of the titanosilicate crystalline phase in the system represents about 12 wt %, and this percentage of the adsorbent fraction can achieve, at 298 K and 20 MPa, 0.14 wt % hydrogen adsorption with respect to the total mass of the system. Following postsynthesis treatments, small amounts of Pd (<0.1 wt %) have been incorporated into the resulting nanoarchitectures in order to improve their hydrogen adsorption capacity. In this way, Pd-layered titanosilicate supported on glass fibers has been tested as a hydrogen adsorbent at diverse pressures and temperatures, giving rise to values around 0.46 wt % at 298 K and 20 MPa. A mechanism of hydrogen spillover involving the titanosilicate framework and the Pd nanoparticules has been proposed to explain the high increase in the hydrogen uptake capacity after the incorporation of Pd into the nanoarchitecture.

Escoliose no contexto de distrofia muscular

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Dermatomiosite, neoplasia da mama e Orlistat : que associação?

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Role of dietary fibers in the nutritional management of hyperuricemia

Foods rich in adenine and hypoxanthine may contribute to the increase of uricemia. Hyperuricemia is associated with other pathological conditions pertaining to metabolic syndrome. Objective: the assessement of the impact of fiber rich diet on uricemia in patients with metabolic syndrome. Methods: the study involved 46 male patients with metabolic syndrome who claimed to have reduced mobility in fingers, hypertension, obesity, hyperglycemia and hyperuricemia. A validated questionnaire about dietary habits was applied at the beginning of the study and after 6 weeks of fiber-rich diet by eliminating from patients diet preparations of animal food and increased intake of vegetable foods. Blood presure, body mass index, blood glucose and uric acids were measured at the beginning of the study and after 6 weeks of fiber rich diet by daily consumption of 2 servings of added grains - 60g totally and vegetables 200g, fruits 300g respectively. Results: The study shows that at baseline all patients had an inadequate dietary intake of dietary fiber, 28.5 ± 2.2 g/day instead of 38 g per day.The increase in fiber intake of 10 ± 5 g/day was associated with a decrease of serum uric acid by 69.87% from 8.3  0.6 mg/dL to 5.8  0.5 mg/dL, p = 0.008, non-significant decrease of BMI (from 26.8  4.5 to 26.4  4.6 kg/m2, p<0.01), significant decrease of glycemia (from 130  0.8 to 105  4.2mg/dL, p <0.001) and significant decrease in blood pressure (from 150  10.6 to 130  8.4 mmHg, p <0.001). Conclusion: The fiber rich diet decreased blood uric acid, blood glucose levels an arterial pressure in patients with metabolic syndrome.

Effects of the fibers distribution in the human eardrum: A biomechanical study

The eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.

Effects of the fibers distribution in the human eardrum: A biomechanical study

The eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.

A detector based on silica fibers for ion beam monitoring in a wide current range

A detector based on doped silica and optical fibers was developed to monitor the profile of particle accelerator beams of intensity ranging from 1 pA to tens of µA. Scintillation light produced in a fiber moving across the beam is measured, giving information on its position, shape and intensity. The detector was tested with a continuous proton beam at the 18 MeV Bern medical cyclotron used for radioisotope production and multi-disciplinary research. For currents from 1 pA to 20 µA, Ce3+ and Sb3+ doped silica fibers were used as sensors. Read out systems based on photodiodes, photomultipliers and solid state photomultipliers were employed. Profiles down to the pA range were measured with this method for the first time. For currents ranging from 1 pA to 3 µA, the integral of the profile was found to be linear with respect to the beam current, which can be measured by this detector with an accuracy of ∼1%. The profile was determined with a spatial resolution of 0.25 mm. For currents ranging from 5 µA to 20 µA, thermal effects affect light yield and transmission, causing distortions of the profile and limitations in monitoring capabilities. For currents higher than ∼1 µA, non doped optical fibers for both producing and transporting scintillation light were also successfully employed.

Fused-quartz fibers : a survey of properties, applications, and production methods /

Bibliography: p. 18-26.