Browsing by Author "Chung, P. C."

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Inelastic light scattering studies of overdoped Y1-xCaxBa2Cu3O7-delta thin film
(2007-12-01)
Lin, J. H.
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Weng, S. M.
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Liu, H. L.
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Chung, P. C.
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Lin, J. -Y.
The vibrational and magnetic Raman excitation spectra were examined in overdoped Y1-xCaxBa2Cu3O7-delta thin films. Below T-c, certain phonons in undoped YBa2Cu3O7-delta (YBCO) show strong self-energy effects, which gradually vanish with increasing Ca concentration into the overdoped regime. The observed B-1g symmetry two-magnon excitation peak near 2900 cm(-1) in YBCO is significantly broadened, weakened, and shifts to the lower frequency with increasing Ca content, indicating the effective value of magnetic superexchange energy decreases and that the life time of the magrions becomes shorter with increasing hole concentrations. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Should spikes be treated with equal weightings in the generation of spectro-temporal receptive fields?
(2010-05-01)
Chang, T. R.
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Chiu, T. W.
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Chung, P. C.
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Poon, Paul W. F.
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交大名義發表
Knowledge on the trigger features of central auditory neurons is important in the understanding of speech processing. Spectro-temporal receptive fields (STRFs) obtained using random stimuli and spike-triggered averaging allow visualization of trigger features which often appear blurry in the time-versus-frequency plot. For a clearer visualization we have previously developed a dejittering algorithm to sharpen trigger features in the STRF of FM-sensitive cells. Here we extended this algorithm to segregate spikes, based on their dejitter values, into two groups: normal and outlying, and to construct their STRF separately. We found that while the STRF of the normal jitter group resembled full trigger feature in the original STRF, those of the outlying jitter group resembled a different or partial trigger feature. This algorithm allowed the extraction of other weaker trigger features. Due to the presence of different trigger features in a given cell, we proposed that in the generation of STRF, the evoked spikes should not be treated indiscriminately with equal weightings. (C) 2009 Elsevier Ltd. All rights reserved.