A self-organizing maps classifier structure for brain computer interfaces

AbstractIntroductionBrain Computer Interfaces provide an alternative communication path to severe paralyzed people and uses electrical signals related to brain activity in order to identify the user’s intention. In this paper a classifier based on a Self-Organizing Map is introduced.MethodsElectroencephalography signal is used on this work as a source for the user’s intention. This signal represents the brain activity and is processed in order to extract the frequency features presented to the classifier, which uses a Self-Organizing Map and a series of probability masks in order to identify the correct class.ResultsThe proposed structure was evaluated using a dataset of Electroencephalography with three mental tasks. The system was able to identify the different states of the users intention with an accuracy of 71.21% for a three-class problem using only 25 neurons for one of the users.ConclusionThe classifier proposed in this paper has an accuracy that is around the value of similar works in the literature, using the same data, but using a small time window for the classification, meaning the system can have a better time response for the user.

Essential oil of Lithraea molleoides (Vell): chemical composition and antimicrobial activity

Lithraea molleoides (Vell.) (Anacardiaceae) is a tree found in Brazil, Paraguay, Bolivia, Uruguay, Argentina and Chile. It is popularly used in the form of alcoholic extracts, decoctions and infusions for the treatment of cough, bronchitis, arthritis, diseases of the digestive system and as diuretic, tranquilizer, haemostatic and tonic agent. The objectives of this study were the extraction of the essential oil of the mature fruit, leaves and aerial parts of the plant and quantification of the yield thereof; the identification and quantification of the principal components of the essential oil and the determination of its antimicrobial activity against bacteria and yeast. The essential oil yield of the mature fruits was 1.0 percent but essential oil was not detected in leaves and flowery branches. The gas chromatograph-mass spectrometer (GC-MS) analysis of the essential oil of the mature fruits detected the presence of limonene (89.89 percent), alpha-pinene (3.48 percent), beta-pinene (2.63 percent), alpha-terpineol (1.27 percent), myrcene (0.64 percent), sabinene hydrate (0.54 percent), 4-terpineol (0.28 percent), camphene (0.22 percent) and delta-3-carene (0.13 percent). The essential oil was active against just a few of the Gram-positive bacteria and yeast tested and did not present antimicrobial activity against Gram-negative bacteria.

Lithraea molleoides(Vell.) (Anacardiaceae) é uma árvore encontrada no Brasil, Paraguai, Bolívia, Uruguai, Argentina e Chile. É popularmente usada na forma de extrato alcoólico, decocção e infusão para o tratamento de tosse, bronquite, artrite, doenças do sistema digestivo, como diurético, tranqüilizante, hemostático e tônico. O objetivo do presente estudo foi a extração do óleo essencial dos frutos maduros, folhas e outras partes aéreas da planta e o rendimento do mesmo; a identificação e quantificação dos principais componentes e a determinação da atividade antimicrobiana. O rendimento do óleo essencial dos frutos maduros foi de 1 por cento, entretanto, não foi encontrado óleo essencial nas partes aéreas da planta. A análise do óleo essencial por cromatografia gasosa com espectrometria de massa, mostrou a presença de limoneno (89,89 por cento), alfa-pineno (3,48 por cento), beta-pineno (2,63 por cento), alfa-terpineol (1.27 por cento), mirceno (0,64 por cento), sabineno (0,54 por cento), 4-terpineol (0,28 por cento), canfeno (0,22 por cento) e delta-3-careno (0,13 por cento). O óleo essencial foi ativo contra algumas bactérias Gram positivas e leveduras testadas e não apresentou atividade contra bactérias Gram negativas.