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There are 42 papers published in subject: > since this site started. |
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1. The effect of reference choices on the spatio-temporal analysis of brain evoked potentials: the use of infinite reference | |||
Dezhong Yao,Li Wang,Lars Arendt-Nelsen,Andrew C. N Chen | |||
Basic Medicine 12 December 2005 | |||
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Abstract:Reference is a very virtual issue in EEG and ERP. Understanding the difference of various references will make the applications more confident. In this work, somatosensory evoked potential (SEP) with stimulation on the right hand was studied. The SEP spatio-temporal analysis was conducted comparatively on five references, left mastoid (contralateral mastoid reference, CM), right mastoid (ipsilateral mastoid reference, IM), linked mastoids (LM), average reference (AR) and the infinity reference (IR) newly proposed in 2001. Among the five, CM is the one used in actual recordings, the other four are obtained by off-line re-referencing. The comparison is conducted on four selected components (P30ms, P40ms, N90ms and P230ms) in both temporal and spatial aspects. The results show that references may have a distinct influence on the amplitudes of the scalp potentials, with relative error at some electrodes larger than 200%, and for some electrodes it may even change the polarity. Pair-wise multiple comparison (Tukey test) shows that the differences of Peak values among various references are very significant (P<0.001) between AR and CM\\IM\\LM, and significant (P<0.05) between IR and CM\\IM\\AR for component P230ms, the amplitude value order is CM/IM 刣 LM>IR>AR. The two-ways (the five References vs. the four Peaks) repeated measures ANOVA test shows the effect of different references depends on various components, there is a statistically significant interaction between Reference and the Peak (P = <0.001). While for the spatial map of the potential amplitude, references will not affect the amplitude map shape if the color-bar is selected automatically, but if a fixed color-bar is chosen for data of various references, they may show some differences. These results mean a common reference is important for producing a comparable result between labs. As IR is theoretically a constant reference, we recommend it as the common choice in the future. | |||
TO cite this article:Dezhong Yao,Li Wang,Lars Arendt-Nelsen, et al. The effect of reference choices on the spatio-temporal analysis of brain evoked potentials: the use of infinite reference[OL].[12 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4226 |
2. Two dictionaries Matching Pursuit for sparse decomposition of signals | |||
Peng Xu,Dezhong Yao | |||
Basic Medicine 08 December 2005 | |||
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Abstract:Signal may be decomposed sparsely and power-focally in an over-complete dictionary with Matching Pursuit (MP). In this paper, proposed is a modified MP method named two dictionaries MP to decompose signal more sparsely. In the iteration procedure of the two dictionaries MP, the over-complete dictionary is classified into two separate dictionaries with the selected and unselected atoms, and in each iteration, the algorithm was designed to have more chances than the original MP to choose the atom in the selected atom dictionary as the optimal atom by a simulate annealing threshold function, thus the algorithm avails for a more sparse decomposition. The decomposition results for a cosine-modulated exponential signal and an actual speech signal showed that the proposed two dictionaries MP could decompose signal more sparsely. | |||
TO cite this article:Peng Xu,Dezhong Yao. Two dictionaries Matching Pursuit for sparse decomposition of signals[OL].[ 8 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4180 |
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