The Reorganization of Human Brain Networks Modulated by Driving Mental Fatigue.

The organization of the brain functional network is associated with mental fatigue, but little is known about the brain network topology that is modulated by the mental fatigue. In this study, we used the graph theory approach to investigate reconfiguration changes in functional networks of different electroen-cephalography (EEG) bands from 16 subjects performing a simulated driving task. Behavior and brain functional networks were compared between the normal and driving mental fatigue states. The scores of subjective self-reports indicated that 90 min of simulated driving-induced mental fatigue. We observed that coherence was significantly increased in the frontal, central, and temporal brain regions. Furthermore, in the brain network topology metric, significant increases were observed in the clustering coefficient (Cp) for beta, alpha, and delta bands and the character path length (Lp) for all EEG bands. The normalized measures γ showed significant increases in beta, alpha, and delta bands, and λ showed similar patterns in beta and theta bands. These results indicate that functional network topology can shift the network topology structure toward a more economic but less efficient configuration, which suggests low wiring costs in functional networks and disruption of the effective interactions between and across cortical regions during mental fatigue states. Graph theory analysis might be a useful tool for further understanding the neural mechanisms of driving mental fatigue.

Identification of gastric cancer-related differentially expressed genes by combining PCA and ICA / 生物医学工程学杂志

Screening potential differentially expressed genes can help us to understand the functions of the genes and their roles in disease development. Due to the different emphases of the principal component analysis and independent component analysis, a novel method that combines principal component analysis and independent component analysis is proposed to identify differentially expressed genes associated with gastric cancer for the improvement of accuracy and credibility of results. This method screens out 16 differentially expressed genes which is significantly related to the occurrence and development of gastric cancer from gastric cancer gene expression data with 7129 genes and 29 samples. These genes are worthy to be studied experimentally. The results of this paper are helpful for revealing the occurrence and development mechanism of gastric cancer.

Extraction of AF signal during atrial fibrillation from single-lead ECG based on non-stationary heartbeat series / 生物医学工程学杂志

The real-time and wireless mobile has become the trend of electrocardiogram (ECG) monitoring system for atrial fibrillation (AF). At present, the ECG with multi-leads (12 leads) is needed by most of AF signal extraction algorithms in order to extract effective AF waves. However, it is not very convenient for patients' movements in a multi-lead ECG monitoring system. Although the traditional template matching method is for single-lead ECG extraction, it is less robust than blind source extraction algorithm, and is affected severely by noise. In view of this,we put forth a new real-time algorithm for extracting AF from the singlelead ECG, using non-stationary heartbeat series during AF to extend dimension (segmentation), and then applying a blind source extraction algorithm to extract the effective AF signal. Experiment results showed that this method could be used to extract AF signal effectively from a single-lead ECG data. Therefore, it is suitable to apply this method to Wireless Monitoring System using single-lead ECG.

Lossless compression of high sampling rate ECG data based on BW algorithm / 生物医学工程学杂志

Now researches of ECG data compression mainly focus on compressing the ECG data of low sampling rate. A BW-based high sampling rate ECG data lossless compression algorithm is proposed in this paper. We apply difference operation to the original ECG data first and take part of the 16-bit binary differential value as 8-bit binary. Then the differential results are coded with the move-to-front coding method in order to make the same characters centralizing in a certain area. Last, we gain a high compression ratio by using the arithmetic coding method further. Our experimental results indicate that this is an efficient lossless compression method suitable for body surface ECG data as well as for heart ECG data. The average compression ratios come up to 3.547 and 3.608, respectively. By comparison with current ECG compression algorithms, our algorithm has gained much improvement in terms of the compression ratio, especially when applied to the high sampling rate ECG data.

Principal component analysis for exploring gene expression patterns / 生物医学工程学杂志

When projecting microarray data of yeast time series into principal component space based on time-points (arrays), we can not only ascribe biologically meaningful explanations to the first few principal components, but also discover sensible gene expression patterns and the according genes with periodic fluctuation this helps the subsequent research of gene periodic expression and gene regulatory network.

Study on the computer-assisted real-time diagnosis for micro-focus of esophagus based on the change of region-gradation / 生物医学工程学杂志

This study was aimed at assessing the effectiveness of Computer-assisted real-time diagnosis for micro-focus of esophagus. Two algorithms, the hues and saturation average of region-gradation (HSARG) and the wave-frequency integral of gradation (WFIG), based on the region-gradation change, were used to analyze the collected images of esophagus by quick, real-time processing. The results show that the image processing software based on the two algorithms mentioned above is effective in some degree for discriminating normal mucosa from the pathological changes of the esophagus such as esophagitis, early carcinoma of esophagus, middle-late carcinoma of esophagus, and atypical hyperplasia of esophagus. So the software may be used as a kind of auxiliary diagnostic measure to screen out the pathological changes of esophagus at clinic effectively.

Research on Registration Algorithm for Three-dimension Cardiac Electrical Maps / 航天医学与医学工程

Objective To align the mapping points from the locations of catheter electrodes with CT/MR image three-dimension data of the cardiac chamber. Methods Most of existing algorithms assumed that two spaces spanned respectively by mapping points and by CT/MR data were orthogonal, and thus modulated only 9 free-degrees of three-dimension translations, rotations and scaling for registration. However, our research showed that the above two spaces might be not always orthogonal. So we introduced affine transformation model based on 12 free-degrees and the corresponding iterative closest point algorithm to realize the registration and further incorporate the registration algorithm with the clinical operations. Combining with OpenGL, we realized the proposed algorithm via Visual C]+]+ 6.0 software. Results Simulation results showed that the residual registration errors on average were decreased from 40 pixels before registration to 1.5 pixels after registration. This algorithm was further validated in animal experiments. Conclusion This proposed three-dimension mapping registration algorithm well realizes the registration in three-dimension cardiac mapping and has practical application values.

An improved motion estimation of medical image series via wavelet transform / 生物医学工程学杂志

The compression of medical image series is very important in telemedicine. The motion estimation plays a key role in the video sequence compression. In this paper, an improved square-diamond search (SDS) algorithm is proposed for the motion estimation of medical image series. The improved SDS algorithm reduces the number of the searched points. This improved SDS algorithm is used in wavelet transformation field to estimate the motion of medical image series. A simulation experiment for digital subtraction angiography (DSA) is made. The experiment results show that the algorithm accuracy is higher than that of other algorithms in the motion estimation of medical image series.

[Study of numerical mapping methods for DNA sequences].

The first problem to be solved is to map DNA sequences onto numerical sequences in bio molecular sequence analysis by mathematical, physical and digital signal processing methods. The characters and the adaptability of eight existing mapping methods are analyzed in this paper. A new numerical mapping method based on the probability of bases in the segment DNA sequence is presented. Most of the coding sequences are characterized by 3 - base periodicity. Further more, eight numerical mapping methods are compared and the new method is verified by means of the spectrum analysis of DNA sequence with 3 - base periodicity. The computer simulation results show that the mapping method based complex plane is superior to the other seven methods in reflecting the original information of the bio-molecular sequence and the quality of the obtained power spectra. The identification rate the new method attains is approximately what the complex plane method has achieved.