IEEE transactions on bio-medical engineering
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IEEE Trans Biomed Eng · Oct 2008
A new oscillometry-based method for estimating the brachial arterial compliance under loaded conditions.
We propose a new method for assessing the compliance of a compressed brachial artery using an oscillometry-based approach that is mathematically based on artery and air-cuff models. The cuff dynamics during the inflation period were characterized by simultaneously recording the cuff volume and internal pressure with a pressure transducer and an airflow meter, respectively, which yielded the envelope of the oscillation amplitudes (OAs) in the air cuff. This allowed the change in the arterial volume during each heartbeat at different cuff pressures to be calculated, yielding a changed volume-pressure curve. ⋯ In addition, the proposed C(osci) was validated by comparing it with the compliance of the brachial artery (Cecho) estimated echocardiographically from the brachial arterial blood flow in 32 patients whose lower limbs exhibited numbness or lack of strength. The results showed that Cosci and Cecho were significantly correlated between the cuff pressures levels and the mean arterial pressure, systolic pressure, and diastolic pressure (r=0.616, 0.571, and 0.666, respectively; p<0.0001). This suggests that a useful measure of the loaded compliance can be derived from the pattern of the OA waveform in addition to oscillometry-based blood pressure measurements.
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IEEE Trans Biomed Eng · Oct 2008
The Berlin Brain--Computer Interface: accurate performance from first-session in BCI-naïve subjects.
The Berlin Brain--Computer Interface (BBCI) project develops a noninvasive BCI system whose key features are: 1) the use of well-established motor competences as control paradigms; 2) high-dimensional features from multichannel EEG; and 3) advanced machine-learning techniques. Spatio-spectral changes of sensorimotor rhythms are used to discriminate imagined movements (left hand, right hand, and foot). A previous feedback study [M. ⋯ Available: http://dx.doi.org/10.1016/j.neuroimage.2007.01.051] with ten subjects provided preliminary evidence that the BBCI system can be operated at high accuracy for subjects with less than five prior BCI exposures. Here, we demonstrate in a group of 14 fully BCI-naIve subjects that 8 out of 14 BCI novices can perform at >84% accuracy in their very first BCI session, and a further four subjects at >70%. Thus, 12 out of 14 BCI-novices had significant above-chance level performances without any subject training even in the first session, as based on an optimized EEG analysis by advanced machine-learning algorithms.