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The repair activity of verbascoside (VER), isolated from Pedicularis spicata, towards the oxidizing hydroxyl radical adduct of dGMP and its reaction mechanism were studied using pulse radiolysis. Upon pulse radiolysis of nitrous oxide saturated aqueous solution of 2'-deoxyguanosine-5'-monophosphate (dGMP) and VER, it was found that the transient absorption spectrum of the hydroxyl adduct of dGMP decays with the formation of that of the phenoxyl radical of VER, several tens of microseconds after the electron pulse. From the formation kinetics of the phenoxyl radical of VER, the rate constant of the repair reaction was determined to be 1.12 x 10(9) dm(3) mol(-1) s(-1).

Traditional studies tend to show that the N2 potential is an index for impulse control. Some researchers doubt that the N2 potential is related to behavior suppression because the impulse control usually occurs in the behavioral inhibition condition. This study investigates whether the N2 potential is associated with the successful suppression of behavior responses in impulse control processes. We recorded event-related potentials (ERPs) while participants performed a go/no-go task (task 1) and a variation of the go/no-go task with reduced behavioral involvement during the impulse control process (task 2). In task 1, we found that, in N2, higher mean amplitude and shorter peak latency were found in the no-go condition than in the go condition. No significant difference was found for either mean amplitude or peak latency between the no-go and go conditions in task 2. Task 1 and task 2 were consistent in task procedure, ERP waveforms, ERP components, and topographical maps in the no-go condition. Results show that, in the no-go condition, the N2 potential was associated with the successful suppression of the behavior response in the impulse control process. Our results indicate that N2 is a combination of behavioral suppression and cognitive control rather than a simple ERP component that marks the cognitive impulse control process.

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Cochlea-scaled spectral entropy (CSE; Stilp & Kluender, PNAS, 107(27):12387-12392 [2010]) is a measure of information-bearing change in complex acoustic signals such as speech. CSE robustly predicts English sentence intelligibility even amidst temporal distortion and widely different speaking rates (Stilp, Kiefte, Alexander, & Kluender, JASA, 128(4):2112-2126). However, CSE does not explicitly capture changes in fundamental frequency (f0) in any way distinct from that for other aspects of spectral shape (e.g., formant patterns, slope). This property of CSE could limit its ability to predict intelligibility of tone languages that use f0 for phonetic and morphological distinctions. The present study assesses the predictive power of CSE for Mandarin Chinese sentence intelligibility. Twenty-five native-Mandarin listeners transcribed Mandarin sentences in which consonant-length (80-ms) and vowel-length (112-ms) segments with either high or low CSE were replaced with speech-shaped noise. CSE reliably predicted listener performance; as greater amounts of CSE were replaced by noise, performance worsened. Results encourage information-theoretic approaches to speech perception, as change and not physical acoustic measures best predict sentence intelligibility across tonal and nontonal languages. [Work supported by NIDCD.]