A new strategy to interpret OCT posterior pole asymmetry analysis for glaucoma diagnosis

AIM：To detect early glaucoma by optical coherence tomography（OCT） posterior pole asymmetry analysis.METHODS：Totally 39 eyes from 39 healthy subjects,40 eyes from 40 mild glaucoma patients,33 eyes from 33 moderate glaucoma patients and 41 eyes from severe glaucoma patients were included in this study.All subjects underwent posterior pole asymmetry analysis（PPAA） of OCT and the posterior pole area was divided into three zones.Means,standard deviations and 95% confidence intervals of each zone asymmetry in control group were assessed.Retina thickness asymmetry（RTA） of different stage of glaucoma were compared for each zone,and receiver operating characteristic（ROC） curves were made to test the efficacy of strategies using different zones to discriminate glaucomatous eyes from the healthy ones.RESULTS：In a healthy population,RTA of the centre zone showed the minimal mean value（3.085 μm）,standard deviation（1.756）,and the narrowest 95% confidence interval（from 2.360 to 3.810 μm）.It was only in the center zone that RTA exhibited significant difference between control and moderate glaucoma group（P〈0.01）,as well as control and severe glaucoma group（P〈0.00001）.The strategy utilized in the center zone had the strongest diagnostic capability（zone 3 AUROC=0.816,P=0.0016） in comparison to that of the periphery area（zone 1 AUROC=0.675,P=0.0016;zone 2 AUROC=0.623,P=0.0197）,the whole posterior pole involved interpreting strategy showed inferior diagnostic power than the centre zone dependent strategy（z=2.851,P=0.0044）.CONCLUSION：Utilizing the posterior pole centre zone to interpret OCT PPAA results are more effective than making use of the whole posterior pole map.

Research on the Drawing-up of the Pole Figure for Orientation Analysis of Directional Si Steel Sheet

The magnetic property of soft magnetic metals and alloys depends strongly on the crystallo-graphic orientation. In automated equipment for orientation research, the intensity for drawing up the pole figure is measured in detail. The present research shows that the accurate pole figure can be drawn up without measuring concretely the intensity. For directional Si steel sheet the measuring step may be 4～5 degrees. In this paper the experimental equation for defo-cusing correction was derived from the experimental data in different specimens with random orientation.

Dynamic modeling and analysis of the closed-circuit grinding-classification process

Mathematical models of the grinding process are the basis of analysis, simulation and control. Most existent models in- cluding theoretical models and identification models are, however, inconvenient for direct analysis. In addition, many models pay much attention to the local details in the closed-circuit grinding process while overlooking the systematic behavior of the process as a whole. From the systematic perspective, the dynamic behavior of the whole closed-circuit grinding-classification process is consid- ered and a first-order transfer function model describing the dynamic relation between the raw material and the product is established. The model proves that the time constant of the closed-circuit process is lager than that of the open-circuit process and reveals how physical parameters affect the process dynamic behavior. These are very helpful to understand, design and control the closed-circuit grinding-classification process.

Rolling Texture in Ti_3Al

The orientation changes and deformation behaviours of a Ti_3Al-based alloy was investigated by using micro-structure obervalion, pole figure and ODF analysis, as well as Chemical micro-analysis. A {0001} fibretexture an0d a weak {1210} <1010> texture were found after 35% cold rolling at room temlierature. The activation process of slip systems was discussed concerning formation of the rolling texture. Because of the low ductility of the material it is believed that the grains were deformed by simple glide suggested by Sachs.

Studying the Effect of the Pre-Stimulation Paradigm on Steady-State Visual Evoked Potentials with Dynamic Models Based on the Zero-Pole Analytical Method

This study explored methods for improving the performance of Steady-State Visual Evoked Potential(SSVEP)-based Brain-Computer Interfaces(BCI), and introduced a new analytical method to quantitatively analyze and reflect the characteristics of SSVEP. We focused on the effect of the pre-stimulation paradigm on the SSVEP dynamic models and the dynamic response process of SSVEP, and performed a comparative analysis of three pre-stimulus paradigms(black, gray, and white). Four dynamic models with different orders(second-and third-order)and with and without a zero point were used to fit the SSVEP envelope. The zero-pole analytical method was adopted to conduct quantitative analysis on the dynamic models, and the response characteristics of SSVEP were represented by zero-pole distribution characteristics. The results of this study indicated that the pre-stimulation paradigm affects the characteristics of SSVEP, and the dynamic models had good fitting abilities with SSVEPs under various types of pre-stimulation. Furthermore, the zero-pole characteristics of the models effectively characterize the damping coefficient, oscillation period, and other SSVEP characteristics. The comparison of zeros and poles indicated that the gray pre-stimulation condition corresponds to a lower damping coefficient, thus showing its potential to improve the performance of SSVEP-BCIs.