919 resultados para Speech Motor Control


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Cytoplasmic dynein is one of the major motor proteins involved in intracellular transport. It is a protein complex consisting of four subunit classes: heavy chains, intermediate chains (ICs), light intermediate chains, and light chains. In a previous study, we had generated new monoclonal antibodies to the ICs and mapped the ICs to the base of the motor. Because the ICs have been implicated in targeting the motor to cargo, we tested whether these new antibodies to the intermediate chain could block the function of cytoplasmic dynein. When cytoplasmic extracts of Xenopus oocytes were incubated with either one of the monoclonal antibodies (m74–1, m74–2), neither organelle movement nor network formation was observed. Network formation and membrane transport was blocked at an antibody concentration as low as 15 μg/ml. In contrast to these observations, no effect was observed on organelle movement and tubular network formation in the presence of a control antibody at concentrations as high as 0.5 mg/ml. After incubating cytoplasmic extracts or isolated membranes with the monoclonal antibodies m74–1 and m74–2, the dynein IC polypeptide was no longer detectable in the membrane fraction by SDS-PAGE immunoblot, indicating a loss of cytoplasmic dynein from the membrane. We used a panel of dynein IC truncation mutants and mapped the epitopes of both antibodies to the N-terminal coiled-coil domain, in close proximity to the p150Glued binding domain. In an IC affinity column binding assay, both antibodies inhibited the IC–p150Glued interaction. Thus these findings demonstrate that direct IC–p150Glued interaction is required for the proper attachment of cytoplasmic dynein to membranes.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Fine finger and hand movements in humans, monkeys, and rats are under the direct control of the corticospinal tract (CST). CST lesions lead to severe, long-term deficits of precision movements. We transected completely both CSTs in adult rats and treated the animals for 2 weeks with an antibody that neutralized the central nervous system neurite growth inhibitory protein Nogo-A (mAb IN-1). Anatomical studies of the rubrospinal tracts showed that the number of collaterals innervating the cervical spinal cord doubled in the mAb IN-1- but not in the control antibody-treated animals. Precision movements of the forelimb and fingers were severely impaired in the controls, but almost completely recovered in the mAb IN-1-treated rats. Low threshold microstimulation of the motor cortex induced a rapid forelimb electromyography response that was mediated by the red nucleus in the mAb IN-1 animals but not in the controls. These findings demonstrate an unexpectedly high capacity of the adult central nervous system motor system to sprout and reorganize in a targeted and functionally meaningful way.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This paper introduces the session "Technology in the Year 2001" and is the first of four papers dealing with the future of human-machine communication by voice. In looking to the future it is important to recognize both the difficulties of technological forecasting and the frailties of the technology as it exists today--frailties that are manifestations of our limited scientific understanding of human cognition. The technology to realize truly advanced applications does not yet exist and cannot be supported by our presently incomplete science of speech. To achieve this long-term goal, the authors advocate a fundamental research program using a cybernetic approach substantially different from more conventional synthetic approaches. In a cybernetic approach, feedback control systems will allow a machine to adapt to a linguistically rich environment using reinforcement learning.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Substantial progress has been made in understanding the genetic basis of temperature-compensated circadian clocks. Ultradian rhythms, with a period shorter than 24 h, are at least as widespread as circadian rhythms. We have initiated genetic analysis of defecation behavior, which is controlled by an ultradian clock in Caenorhabditis elegans. The defecation motor program is activated every 45 sec, and this rhythm is temperature compensated. We describe mutations in 12 genes that either shorten or lengthen the cycle period. We find that most of these mutations also disrupt temperature compensation, suggesting that this process is an integral part of the clock. These genes open the way for molecular genetic dissection of this ultradian clock.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Nas últimas décadas, a indústria automobilística mundial vem investindo no desenvolvimento tecnológico dos motores, com o objetivo de alcançar melhor eficiência energética e atender às legislações que limitam a quantidade de resíduos tóxicos nos gases de exaustão e menor consumo de combustível. Isso resultou na implantação dos sistemas de gerenciamento eletrônico do motor, que possibilitam funcionalidades para se controlar diversas variáveis do motor, aumentando consideravelmente o rendimento do motor. Este trabalho tem como objetivos explorar a dinâmica de um motor de combustão interna ciclo Otto, os sinais elétricos associados, e os componentes de seu gerenciamento eletrônico. A partir dessas informações, o trabalho apresenta o processo de analise dos sinais elétricos e as estratégias de controle utilizadas em um sistema de gerenciamento real. Assim, são desenvolvidos o hardware e o firmware de uma unidade microcontroladora para gerenciamento eletrônico do motor. O hardware foi elaborado com uma concepção centralizada, ou seja, foi usado apenas um microcontrolador de 32-bit para gerenciar todas as funções. O firmware de controle foi desenvolvido de forma modular baseado em modelos de malha fechada. O modelo matemático do motor foi identificado utilizando técnicas de controle em um veículo real, e a avalidação do modelo foi obtida através de testes em um dinamômetro inercial.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

O controle da mistura ar/combustível é muito importante para o correto funcionamento dos motores à combustão interna ciclo Otto. A relação entre o ar e o combustível influencia diretamente no funcionamento do motor, na emissão de poluentes e no consumo de combustível. Este trabalho apresenta o desenvolvimento de um controle da mistura ar/combustível a partir do estudo de modelos de malha fechada deste sistema. Esse controle tem por objetivo manter a mistura o mais próxima possível do ponto estequiométrico, a fim de otimizar a taxa de conversão de gases poluentes pelo catalisador, e utiliza um sensor de oxigênio, conhecido como sonda lambda, para realizar a realimentação do sistema, indicando se a mistura está no ponto estequiométrico. Este trabalho também apresenta o desenvolvimento de um compensador em malha fechada para controlar a mistura a/c (ar/combustível) em outros pontos, além do estequiométrico, através do uso de uma sonda lambda de banda larga.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ejercicios resueltos para la asignatura sistemas de control automático. Control de un motor de corriente continua.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The independence of the mass media has been regularly restricted over the past two years in Ukraine. Following a period of relative freedom in 2005–2010, the scope of direct and indirect government control of the press has increased, cancelling out the achievements of the Orange Revolution in this area. The press in Ukraine is less and less able to perform its role as watchdog on the government and politicians and as a reliable source of information on the situation in the country to the public. This is mainly due to: (1) the concentration of the most important mass media in the hands of Ukraine’s most powerful oligarchs, whose business interests depend on the government; (2) the use of the press as instruments in political and business competition; (3) the ruling class’s subordination of the institutions which supervise the press; (4) repression used against media critical of the government and (5) the lack of an independent public broadcasting corporation. As a consequence, the press has hardly any impact on the political processes taking place ahead of the parliamentary election scheduled for 28 October. This is also an effect of a passiveness present in the Ukrainian public, who are tired of politics and are focused on social issues. Cases of abuse or corruption scandals revealed by the press do not provoke any response from the public and are rarely investigated by the public prosecution authorities. The more popular a given medium is, the more strongly it is controlled by the government. At present, television has to be recognised as the least reliable of the mass media. In turn, Internet news journals are characterised by the greatest pluralism but also have more limited accessibility. The political conditions in which the mass media operate in Ukraine lead to various forms of pathology. The most serious of them are censorship by the owners and self-censorship performed by journalists, and a great share of political advertorials. As the parliamentary election is approaching, the pathologies of the Ukrainian media market have been showing up with greater intensity.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

National Highway Traffic Safety Administration, Washington, D.C.