RESUMO. A lesão cerebral traumática (TCE) é uma das principais causas de incapacidade crônica. Menos de um quarto dos pacientes com TCE moderada e grave melhoraram sua cognição dentro de cinco anos. A estimulação cerebral não invasiva, incluindo a estimulação transcraniana por corrente contínua (ETCC), pode ajudar na reabilitação neurológica, aumentando a neuroplasticidade adaptativa e reduzindo as sequelas patológicas após o TCE. Métodos: pesquisamos os bancos de dados MEDLINE / PubMed e Web of Science. Usamos a escala de Jadad para avaliar os métodos utilizados nos ensaios clínicos. Resultados: os 14 artigos incluídos relataram diferentes desenhos de estudo; 2 estudos foram abertos, 9 foram ensaios clínicos randomizados (ECRs) cruzados e 3 foram ECR de grupos paralelos. A maioria dos estudos utilizou a ETCC anódica do córtex pré-frontal dorsolateral esquerdo, mas os parâmetros de montagem e estimulação variaram. Múltiplos estudos mostraram melhoras nas escalas de recuperação de coma em pacientes com distúrbios da consciência e melhora da cognição. Alguns estudos mostraram alterações nas medidas neurofisiológicas (eletroencefalografia (EEG) e estimulação magnética transcraniana (EMT)), correlacionando com os achados clínicos. Os principais vieses metodológicos foram a falta de relatos de cegamento e randomização. Conclusão: a ETCC é uma técnica neuromodulatória segura e não invasiva que pode ser administrada em monoterapia, mas a utilização da ETCC parece impulsionar os resultados clínicos quando combinada com outras estratégias terapêuticas (como reabilitação cognitiva e fisioterapia). O EEG e o EMT podem ajudar a orientar a pesquisa e tambem mensurar os ganhos clínicos por serem potenciais biomarcadores da neuroplasticidade.

ABSTRACT. Traumatic brain injury (TBI) is a major cause of chronic disability. Less than a quarter of moderate and severe TBI patients improved in their cognition within 5 years. Non-invasive brain stimulation, including transcranial direct current stimulation (tDCS), may help neurorehabilitation by boosting adaptive neuroplasticity and reducing pathological sequelae following TBI. Methods: we searched MEDLINE/PubMed and Web of Science databases. We used Jadad scale to assess methodological assumptions. Results: the 14 papers included reported different study designs; 2 studies were open-label, 9 were crossover randomized clinical trials (RCTs), and 3 were parallel group RCTs. Most studies used anodal tDCS of the left dorsolateral prefrontal cortex, but montages and stimulation parameters varied. Multiple studies showed improved coma recovery scales in disorders of consciousness, and improved cognition on neuropsychological assessments. Some studies showed changes in neurophysiologic measures (electroencephalography (EEG) and transcranial magnetic stimulation (TMS), correlating with clinical findings. The main methodological biases were lack of blinding and randomization reports. Conclusion: tDCS is a safe, non-invasive neuromodulatory technique that can be given as monotherapy but may be best combined with other therapeutic strategies (such as cognitive rehabilitation and physical therapy) to further improve clinical cognitive and motor outcomes. EEG and TMS may help guide research due to their roles as biomarkers for neuroplasticity.

Mufflers are widely used for exhaust noise attenuation in vehicles and machinery. Recent advances in modeling procedures for accurate performance prediction have led to the development of modeling methods for practical muffler components in commercial design. Muffler designers need simple and fast modeling tools, especially in the preliminary design evaluation stages. Finite Element and Boundary Element methods are often used to provide valid results in a wide range of frequencies. However, these methods are time-consuming, its use needs highly trained personnel and the commercial software is usually quite expensive. Therefore, plane wave based models such as the transfer matrix method (TMM) can offer fast initial prototype solutions for muffler designers. In this paper, the principles of TMM for predicting the transmission loss (TL) of a muffler are summarized. The method is applied to different muffler configurations and the numerical predictions are compared with the results obtained by means of an experimental set up. Only stationary, non-dissipative mufflers are considered. The limitation of both the experimental method and the plane wave approach are discussed. The predicted results agreed reasonably well with the measured results in the low frequency range where the firing engine frequency and its first few harmonics are the main sources of noise.

Squeal noise generation during braking is a complicated dynamic problem which automobile manufacturers have confronted for decades. Customer complaints result in significant yearly warranty costs. More importantly, customer dissatisfaction may result in rejection of certain brands of brake systems. In order to produce quality automobiles that can compete in today's marketplace, the occurrence of disc brake squeal noise must be reduced. The addition of a constrained layer material to brake pads is commonly utilized as a means of introducing additional damping to the brake system. Additional damping is one way to reduce vibration at resonance, and hence, squeal noise. The simulation of braking events in dynamometers has typically been the preferred insulator selection process. However, this method is costly, time consuming and often does not provide an insight into the mechanism of squeal noise generation. This work demonstrates the use of modal analysis techniques to select brake dampers for reducing braking squeal. The proposed methodology reduces significantly the insulator selection time and allows an optimized use of the brake dynamometer to validate selected insulators.