This study aimed to identify differences of peptide profiles in stimulated whole saliva among children with and without occurrence of new carious lesions, and to provide a simple way for early diagnosis and prevention of the relapse of severe early childhood caries (s-ECC). Overall, 26 children aged 3–4 years were selected out from all the children in the kindergarten to be involved in the present study, among them 13 were diagnosed as s-ECC and underwent dental treatment, whilst the other 13 were matched by age and sex as control. Stimulated whole saliva samples were collected before treatment, and at 10 days and 4 months after treatment. During follow-up, 7 of the 13 children with s-ECC showed a relapse, and the new carious lesions were then treated. Salivary peptides were detected using the technique of magnetic beads combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Fifteen peptides showed significant differences in the group without occurrence of new carious lesions (CH group). On comparing the CH group and the other group with occurrence of new carious lesions (CR group), no significant differences were observed before treatment, whereas certain peptides showed significant differences at both 10 days and 4 months after treatment. Two peptides (experimental m/z values: 3162.0 Da and 3290.4 Da) exhibited a consistent tendency in cross-sectional and longitudinal comparisons among these groups; these may be associated with recurrence of s-ECC. Based on our findings, it is concluded that different saliva peptide peaks can be detected in s-ECC using MALDI-TOF MS combined with magnetic beads. Moreover, 2 specific peptides with m/z values 3162.0 Da and 3290.4 Da could be promising salivary protein biomarkers for diagnosis of recurrence of s-ECC.

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Bit error rate (BER) performance of the OFDM system has been widely studied on multi-path fading channel with the channel gain being modeled as various distributions. But the statistical distribution of the OFDM signal on the receiver side has neither been well studied, nor given the closeformed expression. In order to design the optimum detection criteria, especially for the hypothesis test of the OFDM symbol, the probability density function (pdf) of the received OFDM signal on the multi-path channel is presented in this paper. At first, the pdf of the frequency domain impulse response of the channel is derived through the characteristic function method. Secondly, we can show that the joint pdf of the complex channel frequency response and the complex additive white Gaussian noise leads to the pdf of the received OFDM symbol under the condition of given transmitted symbol on a given subcarrier. Lastly, the theoretical analysis is verified by the simulations, and the theoretical and simulation results agree with each other perfectly.